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Sample records for phase zone plate

  1. White Light Photorefractive Phase Zone Plates

    NASA Astrophysics Data System (ADS)

    Gao, Yuan-Mei; Liu, Si-Min

    2008-02-01

    Incoherent white light from an incandescent source is employed to fabricate volume phase zone plates in LiNbO3: Fe, for the first time to our knowledge, which can guide and modulate the input white light or laser light. The diffractive efficiency of the white light volume phase zone plates fabricated can reach as high as 12%. In addition, we test the volume phase zone plates by a probe beam and find that the volume phase zone plate is present in the direction perpendicular to the c-axis and absent in the direction parallel to the c-axis. This directly proves the existence of photovoltaic photorefractive anisotropy of white light.

  2. Diffractive efficiency of terahertz zone plates with continuous phase

    NASA Astrophysics Data System (ADS)

    Li, Dehua; Zhao, Yang; Sun, Qingzhen; Zhao, Xiangdong; Zhou, Wei; Liu, Liqiang; Jin, Tao

    2010-10-01

    We presented a design of the zone plate with continuous phase with Polytetrafluoroethylene (PTFE) based on scalar diffraction theory. Diffraction fields of the zone plate with continuous phase and the phase-correcting Fresnel zone plate with incidence of uniform plane wave were analyzed and compared. The effects of the focal length and diameter of the zone plate with continuous phase on the diffraction field were discussed. The simulations of intensity distribution on the focal plane and the optic axis based on Rayleigh-Sommerfeld diffraction formula were completed using Matlab. The results indicate that the zone plate with continuous phase performs better than the phase-correcting Fresnel zone plate. The intensity on the focus of the zone plate with continuous phase is 1.17, 1.35, 2.62 times stronger than that on 8-level, 4-level, 2-level phase-correcting Fresnel zone plate's respectively. The fabrication process might give rise to a phase error, such as groove depth error, surface roughness. The effects of the phase errors on the performance of the zone plate were discussed.

  3. Stepped conical zone plate antenna

    NASA Astrophysics Data System (ADS)

    Wiltse, James C.

    2001-07-01

    The Fresnel zone plate lens was invented and developed for optical frequencies. However, fabrication difficulties at the short optical wavelengths have prevented obtain good efficiencies. At longer microwave or millimeter-wavelengths fabrication is easier and phase correcting zone plate antennas have been used to obtain good efficiencies. This paper describes a new type of phase correcting zone plate having even better efficiency, namely a diffraction efficiency of 99 percent compared to a true lens, and an overall efficiency much better than a true lens. For the usual zone plate antenna employed at microwave or millimeter wavelengths, path length adjustment is accomplished by cutting different depths in a dielectric plate or by using two or more dielectrics having different dielectric constants. The new design uses a tilted cut in a dielectric plate, which more accurately matches the shape of a true lens and produces much lower phase error. The construction is still near and can be made for example, by a milling machine with a tilted bit. For a circular zone plate, the lens is a stepped conical or tapered shape. Because the phase steps are small, the far-field antenna pattern is excellent and sidelobe-levels are very low. Analysis of typical configurations will be given, showing that phase errors are small, lower than those for an eighth-wave corrected phase zone plate.

  4. Fabrication of large-scale multilevel phase-type Fresnel zone plate arrays by femtosecond laser direct writing

    NASA Astrophysics Data System (ADS)

    Yu, Yan-Hao; Tian, Zhen-Nan; Jiang, Tong; Niu, Li-Gang; Gao, Bing-Rong

    2016-03-01

    We report on the fabrication of large-scale eight-level phase-type Fresnel zone plate arrays (FZPAs) by femtosecond-laser direct writing technology. A high-speed galvanometer scanning system was used to fabricate each Fresnel zone plate to realize high fabrication efficiency. To overcome the limited fabrication scale in the case of galvanometer scanning, inter-plate movements were controlled by multi-axis air-bearing precise positioning stages. With the system, FZPAs whose fill-factor was designed to be 100% realized a diffraction efficiency of 89%. The focusing and imaging properties of the FZPAs were also evaluated, and the FZPAs showed high fidelity.

  5. Renewable liquid reflecting zone plate

    DOEpatents

    Toor, Arthur; Ryutov, Dmitri D.

    2003-12-09

    A renewable liquid reflecting zone plate. Electrodes are operatively connected to a dielectric liquid in a circular or other arrangement to produce a reflecting zone plate. A system for renewing the liquid uses a penetrable substrate.

  6. Overriding Plate Controls on Subduction Zone Evolution

    NASA Astrophysics Data System (ADS)

    Sharples, W. K.; Jadamec, M. A.; Moresi, L. N.; Capitanio, F. A.

    2014-12-01

    Seismic data, rock deformation experiments, and geochemical studies indicate variability in the thickness, buoyancy, and strength of the lithosphere at plate boundaries. However, geodynamic models of subduction commonly either omit an overriding plate or do not investigate role of the variation in overriding plate properties on the subduction evolution. We present time-dependent numerical models of subduction that vary the overriding plate thickness, strength, and density and allow for a plate interface that evolves with time via an anisotropic brittle failure rheology. We examine the emergence of (a) asymmetric versus symmetric subduction, (b) trench retreat versus advance, (c) subduction zone geometry, (d) slab stagnation versus penetration into the lower mantle, and (e) flat slab subduction. The majority of the models result in sustained asymmetric subduction. The models demonstrate that trench retreat is correlated with a thin overriding plate, whereas, trench advance is correlated with a thick and/or strong overriding plate. Slab dip, measured at a depth below the plate boundary interface, has a negative correlation with an increase in overriding plate thickness. Overriding plate thickness exerts a first order control over slab penetration into the lower mantle, with penetration most commonly occurring in models with a thick overriding plate. Periods of flat slab subduction occur with thick, strong overriding plates producing strong plate boundary interface coupling. The results provide insight into how the overriding plate plays a role in establishing advancing and retreating subduction, as well as providing an explanation for the variation of slab geometry observed in subduction zones on Earth.

  7. Rough Fresnel zone plates over metallic surfaces.

    PubMed

    Salgado-Remacha, Francisco Javier; Sanchez-Brea, Luis Miguel; Alvarez-Rios, Francisco Javier; Bernabeu, Eusebio

    2010-04-01

    We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh-Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results. PMID:20357856

  8. Zone plate lens antennas for millimeter and submillimeter wavelengths

    NASA Technical Reports Server (NTRS)

    Goldsmith, Paul F.

    1992-01-01

    Zone plate lenses are a type of focusing element which function essentially as differential phase shifters, having a relatively few, coarsely quantized phase delays across the incident beam of radiation. The major advantages are ease of fabrication and much reduced thickness, compared to conventional refractive focusing elements. These considerations are both of particular importance for the submillimeter range, in which manufacturing tolerances for curved optical elements can pose significant problems, and where the absorption of readily available dielectric materials is quite large. In this presentation we briefly review the theory of zone plate lens operations, present a relatively simple method for calculating the aperture efficiency of zone plate lenses used as antennas, and show some theoretical and measured results in the 100 GHz range.

  9. Simulation of high-resolution x-ray zone plates.

    PubMed

    Kurokhtin, Alexei N; Popov, Alexei V

    2002-02-01

    A full-wave approach to quantitative characterization of x-ray zone plate lenses is proposed. Distributed focusing efficiency eta(z) of a multifocus optical element is defined as the energy flux through the Airy disk of a reference perfect lens with variable focal length z. Maxima of this function characterize diffraction efficiencies and spatial resolution of the zone plate foci. The parabolic wave equation is used to take into account diffraction effects inside the optical element. Rough and fuzzy interface models are introduced to describe realistic zone profiles. Numerical simulation reveals the limited capability of zone width reduction to improve the zone plate imaging performance. The possibilities of second-order focus enhancement by optimization of the zone plate thickness, line-to-space ratio, and zone tilt are studied numerically. PMID:11822594

  10. Revealing the architecture of the upper boundary of the Philippine Sea Plate beneath the northern tip of the Izu-Tanzawa Collision Zone, Central Japan, using later-phase of P waves

    NASA Astrophysics Data System (ADS)

    Shuri, Y.; Tsumura, N.

    2010-12-01

    In Izu-Tanzawa Collision Zone (ITCZ), Izu arc collides with Japan arc due to subduction of the Philippine Sea plate (PHP). Recent studies by Kikuchi (2008) and Arai et al. (2009) have revealed that the upper boundary of PHP has a complex geometry in this area. High seismicity near the top boundary of PHP is reported in the front (northern) edge of the ITCZ, which is the transition zone from collision to subduction of PHP, whereas an aseismic zone is located on the western part of the high seismicity region. This spatial variation of seismicity is probably related to the shape of PHP caused by the difference between collisional vs. subductive movements. To better correlate the spatial distribution of seismicity and the plate configuration, we attempt to find a discontinuous surface near the upper boundary of PHP using later phases of P waves. We used seismic-waveform data from the website of Hi-net seismic network. In the high seismicity region, clear later phases of P waves (X phases) are observed in vertical component seismograms recorded at the stations above the high seismicity region. The X phases arrive 0.5s to 2.0s after P arrivals. Time difference between P and X arrivals (X-P times) increases with distances between the plate boundary and the hypocenters. Similarly, X-P times increase as the distances from the northwestern edge of the high seismicity region to the hypocenters increase. These observations suggest two possibilities for the origin of the X phases: (1) a converted wave at the upper boundary of PHP or (2) a reflected wave from the edge of the high seismicity region. First we searched a suitable plane for which calculated X-P times can match the observed X-P times, by assuming the X phases are converted waves. We found that two converted planes located at different depths would best explain all observed X-P times simultaneously; the depth of the estimated plane in the western side of the high seismicity zone is deeper than that of the eastern side

  11. Large-Area Zone Plate Fabrication with Optical Lithography

    SciTech Connect

    Denbeaux, G.

    2011-09-09

    Zone plates as condenser optics for x-ray microscopes offer simple optical designs for both illumination and spectral resolution when used as a linear monochromator. However, due to the long write times for electron beam lithography, both the availability and the size of zone plates for condensers have been limited. Since the resolution provided by the linear monochromator scales almost linearly with the diameter of the zone plate, the full potential for zone plate monochromators as illumination systems for x-ray microscopes has not been achieved. For example, the 10-mm-diameter zone plate has demonstrated a spectral resolution of E/{Delta}E = 700[1], but with a 26-mm-diameter zone plate, the calculated spectral resolution is higher than E/{Delta}E = 3000. These large-area zone plates are possible to fabricate with the leading edge semiconductor lithography tools such as those available at the College of Nanoscale Science and Engineering at the University at Albany. One of the lithography tools available is the ASML TWINSCAN XT: 1950i with 37-nm resolution [2]. A single 300-mm wafer can contain more than 60 fields, each with a large area condenser, and the throughput of the tool can be more than one wafer every minute.

  12. Ponderomotive phase plate for transmission electron microscopes

    DOEpatents

    Reed, Bryan W.

    2012-07-10

    A ponderomotive phase plate system and method for controllably producing highly tunable phase contrast transfer functions in a transmission electron microscope (TEM) for high resolution and biological phase contrast imaging. The system and method includes a laser source and a beam transport system to produce a focused laser crossover as a phase plate, so that a ponderomotive potential of the focused laser crossover produces a scattering-angle-dependent phase shift in the electrons of the post-sample electron beam corresponding to a desired phase contrast transfer function.

  13. Nature of the plate contact and subduction zones diversity

    NASA Astrophysics Data System (ADS)

    De Franco, Roberta; Govers, Rob; Wortel, Rinus

    2008-07-01

    In recent studies we showed that the nature of the plate contact in subduction zones is an important physical feature in both oceanic lithospheric subduction and continental collision. We investigated two fundamental states of the plate contact: one based on a fault and the other based on a subduction channel. Using geodynamic modeling, we determined the specific signatures of both states of the subduction contact. We established that the nature of the plate contact influences the dynamic response of the overriding and subducting plate, and is one of the controlling factors whether back-arc extension develops or not. In the present study, we combine results of our previous numerical experiments with a re-analysis of published observations. Overall, our synthesis connects seismic moment release with back-arc deformation and tectonic processes at the margin. It leads us to identify four classes of subduction zones. The first two classes result directly from our numerical experiments. In class 1, subduction zones are characterized by a plate contact that is largely fault-like with an accretionary margin. In class 2, the plate contacts are largely channel-type and have an erosive margin. Class 3, where the plate contact is entirely channel-like, consists of accretionary margins with a high sediment supply. Subduction zones of class 4, mostly characterized by an erosive convergent margin (northern Chile, Peru, Honshu and Kuril), are more complicated. They can be explained by incorporating regional observations.

  14. Soft x-ray microscope with zone plates at UVSOR

    NASA Astrophysics Data System (ADS)

    Watanabe, Norio; Shimanuki, Yoshio; Taniguchi, Mieko; Kihara, Hiroshi

    1993-01-01

    A soft x-ray microscope with zone plates was set up at UVSOR (Okazaki, Japan). A 0.41 micrometers line and space pattern was clearly distinguished using an objective zone plate with the outermost zone width of 0.41 micrometers . Modulation transfer functions were measured at wavelengths of 3.1 nm and 5.4 nm, and compared with theoretical calculations. Considering the resolution of a microchannel plate used as a detector, the agreement is fairly good. With this microscope, some biological specimens such as diatoms, spicule of trepang, crab and rabbit muscles, human blood cells, human chromosomes, and magnetotactic bacterium were observed at 3.1 nm and 5.4 nm. With an environmental chamber (wet cell) using polypropylene foils as windows, wet specimens were observed at a wavelength of 4.6 nm. Images of spicule of trepang, human blood cell, and cultured protoplast of plant cell stained by methyl mercury were observed with good contrast.

  15. Moessbauer-Fresnel zone plate as nuclear monochromator

    SciTech Connect

    Mooney, T.M.; Alp, E.E.; Yun, W.B.

    1992-06-01

    Zone plates currently used in x-ray optics derive their focusing power from (a spatial variation of) the electronic refractive index -- that is, from the collective effect of electronic x-ray-scattering amplitudes. Nuclei also scatter x rays, and resonant nuclear-scattering amplitudes, particularly those associated with Moessbauer fluorescence, can dominate the refractive index for x-rays whose energies are very near the nuclear-resonance energy. A zone plate whose Fresnel zones are filled alternately with {sup 57}Fe and {sup 56}Fe ({sup 57}Fe has a nuclear resonance of natural width {Gamma} = 4.8 nano-eV at 14.413 keV; {sup 56}Fe has no such resonance) has a resonant focusing efficiency; it focuses only those x-rays whose energies are within several {Gamma} of resonance. When followed by an absorbing screen with a small pinhole, such a zone plate can function as a synchrotron-radiation monochromator with an energy resolution of a few parts in 10{sup 12}. The energy-dependent focusing efficiency and the resulting time-dependent response of a resonant zone plate are discussed.

  16. Dynamic Linkages Between the Transition Zone & Surface Plate Motion in 2D Models of Subduction

    NASA Astrophysics Data System (ADS)

    Arredondo, K.; Billen, M. I.

    2014-12-01

    Subduction zones exhibit a wide range of behavior, from slab stagnation at 660 km to direct penetration into the lower mantle. Due to uncertainties in the tectonic history of individual subduction zones, such as trench velocities, potential mechanisms for controlling slab behavior in the transition zone are explored using numerical models. Numerical simulations have utilized a range of assumptions to improve computational efficiency, such as ignoring latent heat, ignoring compositional effects or fixing the trench location: the net effect of these assumptions resulting modeled dynamics remains unclear. Additionally the eight major, composition-dependent, phase transitions for pyrolite, harzburgite and eclogite may be an important influence on subducting slab dynamics due to the additional forces that are dependent on depth and compositional layering within the slab (e.g., Ricard et al., 2005). With the goal of developing more complete, self-consistent, and less idealized simulations, we test the importance of various factors on slab behavior: the presence of shear, adiabatic and latent heating, compositional layering, composition-dependent phase transitions and explicit plate speeds versus dynamically evolving plate and trench velocities. Preliminary results indicate that individual components have a relatively minor effect, but produce large changes when combined together. The extent of slab folding and stagnation is overestimated by only modeling the 410 and 660 km phase transitions. Dynamic models with all seven composition-dependent phase transitions are very sensitive to the plate strength and weak zone viscosity, causing large changes in plate speed and slab detachment. Changes to the overriding plate buoyance and strength investigate the origin and influence of trench movement on slab deformation. These feedbacks and parameter-sensitive behavior indicate that the wide range of observed slab behavior may result from subtle differences in plate and plate

  17. High resolution Fresnel zone plate laser alignment system

    SciTech Connect

    Bressler, V.E.; Fischer, G.E.; Ruland, R.E.; Wang, T.

    1992-03-01

    The existing Fresnel zone plate laser alignment system is currently being extended and upgraded for the Final Focus Test Beam (FFTB). Previously, the resolution of this system has been several tens of micrometers. After the upgrade, the resolution will be a few micrometers. Details of the upgrade as well as simulation and experimental results will be presented.

  18. Near-field focusing properties of zone plates in visible regime--new insights.

    PubMed

    Mote, Rakesh G; Yu, S F; Ng, B K; Zhou, Wei; Lau, S P

    2008-06-23

    Near-field focusing properties of zone plates are investigated in the visible regime by a 3-dimensional finite-difference time-domain method. It is shown that Frensel zone plates (FZPs) with metallic coatings can achieve subwavelength focusing in the visible wavelength. The characteristics of subwavelength focusing are found to be independent of the type of metal coatings used. All the FZPs exhibit similar shift in focal length and depth of focus when compared with classical calculations. These results indicate that plasmonic waves do not contribute to subwavelength focusing. Instead the subwavelength focusing characteristic is attributed to the interference of diffracted evanescent waves from a large numerical aperture. It is found that the near-field focusing of FZPs suppresses higher order foci such that the corresponding diffraction efficiency is improved. The use of phase zone plate structured on glass without opaque coating is proposed to improve the diffraction efficiency of subwavelength focusing. PMID:18575522

  19. Phase-Scrambler Plate Spreads Point Image

    NASA Technical Reports Server (NTRS)

    Edwards, Oliver J.; Arild, Tor

    1992-01-01

    Array of small prisms retrofit to imaging lens. Phase-scrambler plate essentially planar array of small prisms partitioning aperture of lens into many subapertures, and prism at each subaperture designed to divert relatively large diffraction spot formed by that subaperture to different, specific point on focal plane.

  20. Subduction Zone Diversity and Nature of the Plate Contact

    NASA Astrophysics Data System (ADS)

    Defranco, R.; Govers, R.; Wortel, R.

    2008-12-01

    We recently showed that the overall dynamics of subduction and initial collision depends on whether the plate contact is a fault or a channel. Here, we combine results of our numerical experiments with a re-analysis of published observations. Overall, our synthesis connects seismic moment release with back-arc deformation and tectonic processes at the margin. It leads us to identify four classes of subduction zones. The first two classes results directly from our numerical experiments. In class 1, subduction zones are characterized by a plate contact that is largely fault-like with an accretionary margin. In class 2, the plate contacts are largely channel-type and have an erosive margin. Class 3, where the plate contact is entirely channel-like, consists of accretionary margins with a high sediment supply. Subduction zones of class 4, mostly characterized by an erosive convergent margin (northern Chili, Peru, Honshu and Kuril), are more complicated. They can be explained by incorporating regional observations.

  1. Zone-Doubled Fresnel Zone Plates for Scanning Transmission X-ray Microscopy

    NASA Astrophysics Data System (ADS)

    Vila-Comamala, J.; Gorelick, S.; Färm, E.; Kewish, C. M.; Diaz, A.; Guzenko, V. A.; Barrett, R.; Raabe, J.; Menzel, A.; Bunk, O.; Ritala, M.; David, C.

    2011-09-01

    We demonstrate the highest spatial resolution reported in scanning transmission x-ray microscopy to date. For the first time in x-ray microscopy, features below 10 nm in width were resolved in the soft x-ray regime (1.2 keV) and 20-nm lines and spaces were visible at multi-keV photon energies (6.2 keV). These achievements were accomplished using zone-doubled Fresnel zone plates. These lenses were fabricated by combining electron-beam lithography and atomic layer deposition of iridium. Diffraction efficiencies up to 8% were measured for zone-doubled Fresnel zone plates with an outermost zone width of 25 nm at 6.2-keV photon energy.

  2. Geophysical Limitations on the Habitable Zone: Volcanism and Plate Tectonics

    NASA Astrophysics Data System (ADS)

    Noack, Lena; Rivoldini, Attilio; Van Hoolst, Tim

    2016-04-01

    Planets are typically classified as potentially life-bearing planets (i.e. habitable planets) if they are rocky planets and if a liquid (e.g. water) could exist at the surface. The latter depends on several factors, like for example the amount of available solar energy, greenhouse effects in the atmosphere and an efficient CO2-cycle. However, the definition of the habitable zone should be updated to include possible geophysical constraints, that could potentially influence the CO2-cycle. Planets like Mars without plate tectonics and no or only limited volcanic events can only be considered to be habitable at the inner boundary of the habitable zone, since the greenhouse effect needed to ensure liquid surface water farther away from the sun is strongly reduced. We investigate if the planet mass as well as the interior structure can set constraints on the occurrence of plate tectonics and outgassing, and therefore affect the habitable zone, using both parameterized evolution models [1] and mantle convection simulations [1,2]. We find that plate tectonics, if it occurs, always leads to sufficient volcanic outgassing and therefore greenhouse effect needed for the outer boundary of the habitable zone (several tens of bar CO2), see also [3]. One-plate planets, however, may suffer strong volcanic limitations. The existence of a dense-enough CO2 atmosphere allowing for the carbon-silicate cycle and release of carbon at the outer boundary of the habitable zone may be strongly limited for planets: 1) without plate tectonics, 2) with a large planet mass, and/or 3) a high iron content. Acknowledgements This work has been funded by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office through the Planet Topers alliance, and results within the collaboration of the COST Action TD 1308. References Noack, L., Rivoldini, A., and Van Hoolst, T.: CHIC - Coupling Habitability, Interior and Crust, INFOCOMP 2015, ISSN 2308-3484, ISBN 978

  3. Numerical modeling of optical properties of a system of two zone plates for focusing hard synchrotron radiation

    SciTech Connect

    Kohn, V. G. Snigireva, I. I.; Snigirev, A. A.

    2006-12-15

    Results of numerical experiments on focusing of a monochromatic spherical wave by a system of two linear zone plates are reported. Calculations were performed for a photon energy of 12.3985 keV and zone plates with a radius of the first zone of 5 {mu}m, a number of zones of 628, and an aperture of 250 {mu}m. To calculate the Kirchhoff integrals, the double Fourier transform method was used and the fast Fourier transform procedure on a grid with a number of points 65 536 = 2{sup 16} was applied. On the basis of the calculation results, a conclusion was drawn that two zone plates operate as one with a doubled phase shift in zones with a material if the longitudinal distance between them is smaller than 1/3 of the focus depth and the transverse displacement is smaller than 1/3 of the outermost zone width (the focus size). If the distance (displacement) exceeds the focus depth (size), the two zone plates operate independently, similar to refracting lenses with a set of different focusing orders, including the zero order. The nature of the moire pattern at a transverse displacement of the zone plates is discussed.

  4. Measuring Transient Signals in Plate Boundary Faults Zones with Strainmeters

    NASA Astrophysics Data System (ADS)

    Hodgkinson, Kathleen; Mencin, Dave; Phillips, David; Henderson, Brent; Gottlieb, Mike; Gallaher, Warren; Johnson, Wade; Pyatt, Chad; Van Boskirk, Elizabeth; Fox, Otina; Mattioli, Glen; Meertens, Chuck

    2014-05-01

    One of the fundamental goals the U.S. National Science Foundation (NSF) funded Earthscope program was to provide a high-quality, continuous geodetic data set that would allow the scientific community to study the evolution of plate boundary zones. Of particular importance was enabling investigation of the role aseismic transient deformation plays in the release of accumulated stress. For example, to allow the comparison of the amount of strain released through Episodic Tremor and Slip (ETS) events to that released in subduction zone earthquakes or, provide the ability to geodetically illuminate the kinematics of fault creep in strike-slip fault zones. The ability to easily integrate these measurements with compatible geophysical data sets was also an essential objective. With goals such as these in mind NSF funded the Plate Boundary Observatory (PBO) to record the continuous deformation field across the western US Plate Boundary. PBO, built and operated by UNAVCO, now consists of over 1100 GPS stations, 76 co-located borehole strain and seismic sites, 6 long baseline strainmeters, Depending on the scientific questions being addressed sites may also have tiltmeter, meteorological, pore pressure and meteorological instrumentation. This presentation will focus on the transient deformation signals recorded by the PBO strainmeter network. PBO strainmeters, which excel in recording signals on the order of nanostrain over hours, have provided unprecedented temporal resolution of aseismic transients such as ETS events in the Cascadia subduction zone, creep signals along the central section of the San Andreas fault system and tsunami generated strain waves. UNAVCO is responsible not only for the ongoing operation of PBO but also the generation of data products associated with each instrument type. In this presentation we will highlight some of the transient signals these instruments have captured, outline the processing steps required to extract these signals data and

  5. Owen Fracture Zone: The Arabia-India plate boundary unveiled

    NASA Astrophysics Data System (ADS)

    Fournier, M.; Chamot-Rooke, N.; Rodriguez, M.; Huchon, P.; Petit, C.; Beslier, M. O.; Zaragosi, S.

    2011-02-01

    We surveyed the Owen Fracture Zone at the boundary between the Arabia and India plates in the NW Indian Ocean using a high-resolution multibeam echo-sounder (Owen cruise, 2009) for search of active faults. Bathymetric data reveal a previously unrecognized submarine fault scarp system running for over 800 km between the Sheba Ridge in the Gulf of Aden and the Makran subduction zone. The primary plate boundary structure is not the bathymetrically high Owen Ridge, but is instead a series of clearly delineated strike-slip fault segments separated by several releasing and restraining bends. Despite an abundant sedimentary supply by the Indus River flowing from the Himalaya, fault scarps are not obscured by recent deposits and can be followed over hundreds of kilometres, pointing to very active tectonics. The total strike-slip displacement of the fault system is 10-12 km, indicating that it has been active for the past ~ 3 to 6 Ma if its current rate of motion of 3 ± 1 mm yr- 1 has remained stable. We describe the geometry of this recent fault system, including a major pull-apart basin at the latitude 20°N, and we show that it closely follows an arc of small circle centred on the Arabia-India pole of rotation, as expected for a transform plate boundary.

  6. Towards multi-order hard X-ray imaging with multilayer zone plates

    PubMed Central

    Osterhoff, Markus; Eberl, Christian; Döring, Florian; Wilke, Robin N.; Wallentin, Jesper; Krebs, Hans-Ulrich; Sprung, Michael; Salditt, Tim

    2015-01-01

    This article describes holographic imaging experiments using a hard X-ray multilayer zone plate (MZP) with an outermost zone width of 10 nm at a photon energy of 18 keV. An order-sorting aperture (OSA) is omitted and emulated during data analysis by a ‘software OSA’. Scanning transmission X-ray microscopy usually carried out in the focal plane is generalized to the holographic regime. The MZP focus is characterized by a three-plane phase-retrieval algorithm to an FWHM of 10 nm. PMID:26089748

  7. Microfabrication of Fresnel zone plates by laser induced solid ablation

    NASA Astrophysics Data System (ADS)

    Rodrigues, Vanessa R. M.; Thomas, John; Santhosh, Chidangil; Ramachandran, Hema; Mathur, Deepak

    2016-07-01

    A novel and simple single-step method of inscribing optical elements on metal-coated transparent substrates is demonstrated. Laser induced solid ablation (LISA) demands very low laser energies (nJ), as can be amply provided by a femtosecond laser oscillator. Here, LISA is used to write Fresnel zone plates on indium and tungsten coated glass. With up to 100 zones, remarkable agreement is obtained between measured and expected values of the focal length. LISA has enabled attainment of focal spot sizes that are 38% smaller than what would be obtained using conventional lenses of the same numerical aperture. The simplicity with which a high degree of automation can readily be achieved using LISA makes this cost-effective method amenable to a wide variety of applications related to microfabrication of optical elements.

  8. Plate Tectonics: From Plate Boundary Zone Tectonics To Extensive Intraplate Tectonics

    NASA Astrophysics Data System (ADS)

    Ishikawa, M.

    2004-12-01

    Plates makes up earth's surface, and tectonic activity is generally concentrated on plate boundary zones. In restrict meaning, plate tectonics of the earth is regarded as mixture of plate boundary zone tectonics and extensive intraplate tectonics. For example, the Asian continent never behaves as rigid plate that was deformed extensively when the Indian continent collided with it. I infer that extensive intraplate tectonics reflects rheological weakening of wet mantle. To demonstrate effect of H2O component on plate strength, one-dimensional rheological profiles of 100 km depth were constructed by assuming 20km thick upper crust and 20km thick lower crust. Temperature-depth profiles were calculated based on one-dimensional steady-state static heat transfer at given surface heat flows. Power law creep and Byerlee_fs law were used to estimate strength in ductile regime and brittle regime respectively. Creep strength for upper crust, lower crust, dry mantle and wet mantle were calculated using creep parameters of granite, granulite, dry dunite and wet dunite. The minimum value between power law creep strength and Byerlee_fs law strength gives the strength of the lithosphere. Strength profile at surface heat flow of 55mW/m2 (continental average is 56.5mW/m2) and strain rate of 10-15/s (intraplate deformation is about 10-15/s - 10-16/s in Asia) shows a significant difference in strength for using dry mantle and wet mantle. In case of dry mantle, the uppermost mantle is quite strong. However, if wet peridotite represent the upper mantle, there is very little strength in the uppermost mantle. The cumulative lithospheric strength, i.e. integral strength from surface to 100km depth, and the cumulative mantle strength, i.e. integral strength from 40km to 100km depth were calculated with changing strain rate. For example, to deform continental lithosphere at strain rate of 10-15/s, wet mantle has a cumulative strength of about 2x1012N/m whereas the cumulative strength of dry

  9. Thin Fresnel zone plate lenses for focusing underwater sound

    SciTech Connect

    Calvo, David C. Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N.

    2015-07-06

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens.

  10. Imaging by Zernike phase plates in the TEM.

    PubMed

    Edgcombe, C J

    2016-08-01

    The images produced from simple phase objects, lenses and Zernike phase plates when all have rotational symmetry can be calculated by 1D Fourier-Bessel transforms. For a simple disc object producing a uniform phase shift over its diameter, the resulting image can be defined for any size of object phase change. The monotonic range of intensity variation with object phase is found to depend strongly on the phase change introduced by the phase plate; this property of the system is not well predicted by the weak phase approximation. The effect of spreading the phase transition at the plate over a range of radius is beneficial if the plate phase change is sufficiently small. Weak-phase calculations for a phase distribution more typical of a spherical object are also shown. PMID:27183505

  11. Fracture initiation by local brittle zones in weldments of quenched and tempered structural alloy steel plate

    SciTech Connect

    Kenney, K.L.; Reuter, W.G.; Reemsnyder, H.S.; Matlock, D.K.

    1997-12-31

    The heat-affected zone (HAZ) embrittlement of an API 2Y Grade 50T quenched and tempered offshore structural steel plate, welded by the submerged-arc process at a heat input of 4.5 kJ/mm, was investigated from the viewpoint of identifying the local brittle zone (LBZ) microstructure and the metallurgical factors associated with its formation. Microstructural and fractographic analysis showed the LBZ microstructure to be dual phase martensite-austenite (M-A) constituent. The formation of M-A constituent was found to be related to microstructural banding of the hot-rolled base plate. When the banded base plate was welded, M-A constituent formed only within the band microstructure which penetrated the intercritically-reheated coarse-grain HAZ (IRCGHAZ). The chemistry of the band microstructure in conjunction with the thermal cycle of the IRCGHAZ provided the critical conditions for the formation of M-A constituent in the API 2Y Grade 50T steel investigated. The influence of local brittle zones (i.e., M-A constituent) on the HAZ fracture toughness was evaluated by means of Crack-Tip Opening Displacement (CTOD) tests. These tests showed the steel to suffer embrittlement when the fatigue precrack sampled an intercritically-reheated coarse-grain HAZ which contained M-A constituent, confirming that M-A constituent is the major microstructural factor controlling the HAZ toughness of this particular steel.

  12. High-efficiency zone-plate optics for multi-keV X-ray focusing.

    PubMed

    Mohacsi, Istvan; Karvinen, Petri; Vartiainen, Ismo; Guzenko, Vitaliy A; Somogyi, Andrea; Kewish, Cameron M; Mercere, Pascal; David, Christian

    2014-05-01

    High-efficiency nanofocusing of hard X-rays using stacked multilevel Fresnel zone plates with a smallest zone width of 200 nm is demonstrated. The approach is to approximate the ideal parabolic lens profile with two-, three-, four- and six-level zone plates. By stacking binary and three-level zone plates with an additional binary zone plate, the number of levels in the optical transmission function was doubled, resulting in four- and six-level profiles, respectively. Efficiencies up to 53.7% focusing were experimentally obtained with 6.5 keV photons using a compact alignment apparatus based on piezoelectric actuators. The measurements have also been compared with numerical simulations to study the misalignment of the two zone plates. PMID:24763638

  13. Hard-x-ray microscopy with Fresnel zone plates reaches 40 nm Rayleigh resolution

    SciTech Connect

    Chu, Y. S.; Yi, J. M.; De Carlo, F.; Shen, Q.; Lee, Wah-Keat; Wu, H. J.; Wang, C. L.; Wang, J. Y.; Liu, C. J.; Wang, C. H.; Wu, S. R.; Chien, C. C.; Hwu, Y.; Tkachuk, A.; Yun, W.; Feser, M.; Liang, K. S.; Yang, C. S.; Je, J. H.; Margaritondo, G.

    2008-03-10

    Substantial improvements in the nanofabrication and characteristics of gold Fresnel zone plates yielded unprecedented resolution levels in hard-x-ray microscopy. Tests performed on a variety of specimens with 8-10 keV photons demonstrated a first-order lateral resolution below 40 nm based on the Rayleigh criterion. Combined with the use of a phase contrast technique, this makes it possible to view features in the 30 nm range; good-quality images can be obtained at video rate, down to 50 ms/frame. The important repercussions on materials science, nanotechnology, and the life sciences are discussed.

  14. Seismicity and structure of Nazca Plate subduction zone in southern Peru

    NASA Astrophysics Data System (ADS)

    Lim, H.; Kim, Y.; Clayton, R. W.

    2015-12-01

    We image the Nazca plate subduction zone system by detecting and (re)locating intra-slab earthquakes in southern Peru. Dense seismic arrays (PeruSE, 2013) were deployed along four lines to target geophysical characterization of the subduction system in the transition zone between flat and normal dipping segments of the Nazca plate (2-15°S). The arc volcanism is absent near the flat slab segment, and currently, the correlation between the location of the active volcanic front and corresponding slab depth is neither clear nor consistent between previously published models from seismicity. We detect 620 local earthquakes from August 2008 to February 2013 by manually picking 6559 and 4145 arrival times for P- and S-phases, respectively. We observe that the S-phase data is helpful to reduce the trade-off between origin time and depth of deeper earthquakes (>100 km). Earthquake locations are relocated to constrain the Nazca slab-mantle interface in the slab-dip transition zone using 7322 measurements of differential times of nearby earthquake pairs by waveform cross-correlation. We also employ the double-difference tomography (Zhang and Thurber, 2003) to further improve earthquake source locations and the spatial resolution of the velocity structure simultaneously. The relocated hypocenters clearly delineate the dipping Wadati-Benioff zone in the slab-dip transition zone between the shallow- (25°) to-flat dipping slab segment in the north and the normal (40°) dipping segment in the south. The intermediate-depth seismicity in the flat slab region stops at a depth of ~100 km and a horizontal distance of ~400 km from the trench. We find a significant slab-dip difference (up to 10°) between our relocated seismicity and previously published slab models along the profile region sampling the normal-dip slab at depth (>100 km).

  15. Ray transfer matrix for a spiral phase plate.

    PubMed

    Eggleston, M; Godat, T; Munro, E; Alonso, M A; Shi, H; Bhattacharya, M

    2013-12-01

    We present a ray transfer matrix for a spiral phase plate. Using this matrix we determine the stability of an optical resonator made of two spiral phase plates and trace stable ray orbits in the resonator. Our results should be relevant to laser physics, optical micromanipulation, quantum information, and optomechanics. PMID:24323013

  16. HSQ double patterning process for 12 nm resolution x-ray zone plates

    SciTech Connect

    Chao, Weilun; Kim, Jihoon; Rekawa, Senajith; Fischer, Peter; Anderson, Erik H.

    2009-06-16

    Soft x-ray zone plate microscopy is a powerful nano-analytic technique used for a wide variety of scientific and technological studies. Pushing its spatial resolution to 10 nm and below is highly desired and feasible due to the short wavelength of soft x-rays. Instruments using Fresnel zone plate lenses achieve a spatial resolution approximately equal to the smallest, outer most zone width. We developed a double patterning zone plate fabrication process based on a high-resolution resist, hydrogen silsesquioxane (HSQ), to bypass the limitations of conventional single exposure fabrication to pattern density, such as finite beam size, scattering in resist and modest intrinsic resist contrast. To fabricate HSQ structures with zone widths in the order of 10 nm on gold plating base, a surface conditioning process with (3-mercaptopropyl) trimethoxysilane, 3-MPT, is used, which forms a homogeneous hydroxylation surface on gold surface and provides good anchoring for the desired HSQ structures. Using the new HSQ double patterning process, coupled with an internally developed, sub-pixel alignment algorithm, we have successfully fabricated in-house gold zone plates of 12 nm outer zones. Promising results for 10 nm zone plates have also been obtained. With the 12 nm zone plates, we have achieved a resolution of 12 nm using the full-field soft x-ray microscope, XM-1.

  17. First epoch geodetic measurements with the Global Positioning System across the northern Caribbean plate boundary zone

    NASA Technical Reports Server (NTRS)

    Dixon, T. H.; Gonzalez, G.; Lichten, S. M.; Katsigris, E.

    1991-01-01

    The first geodetic survey across the northern Caribbean plate boundary zone with GPS was conducted in June 1986. Baseline vectors defined by the six-station regional GPS network ranged from 170 to 1260 km in length. Repeatability of independent daily baseline estimates was better than 8 mm plus 1.3 parts in 10 to the 8th of baseline length for horizontal components. The wet tropospheric path delay during the experiment was both high, sometimes exceeding 30 cm at zenith, and variable, sometimes exceeding 5 cm variation over several hours. Successful carrier phase cycle ambiguity resolution (bias fixing) could not be achieved prior to construction of a regional troposphere model. With optimum troposphere treatment and single-day orbital arcs, most biases on baselines were resolved up to about 550 km in length. With multiday orbital arcs most biases in the network were resolved regardless of baseline length. The results suggest that constraints on plate-boundary zone deformation in the Greater Antilles, and on the North America-Caribbean relative plate motion vector, can be obtained with a series of GPS experiments spanning less than 10 and 15 years, respectively.

  18. Solar Sail - Fresnel Zone Plate Lens for a Large Space Based Telescope

    SciTech Connect

    Early, J T

    2002-02-13

    A Fresnel zone plate lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by missions to the asteroids, Pluto, Kuiper belt or the tort cloud and could also enable meaningful interstellar fly-by missions for laser propelled sails. This type of lens may also have some potential for laser communications and as a solar concentrator. The techniques for fabrication of meter size and larger Fresnel phase plate optics are under development at LLNL, and we are extending this technology to amplitude zone plates made from sail materials. Corrector optics to greatly extend the bandwidth of these Fresnel optics will be demonstrated in the future. This novel telescope concept will require new understanding of the fabrication, deployment and control of gossamer space structures. It will also require new materials technology for fabricating these optics and understanding their long term stability in a space environment.

  19. Demonstration of 12 nm resolution Fresnel zone plate lens based soft x-ray microscopy

    SciTech Connect

    Chao, W.; Kim, J.; Rekawa, S.; Fischer, P.; Anderson, E. H.

    2009-06-05

    To extend soft x-ray microscopy to a resolution of order 10 nm or better, we developed a new nanofabrication process for Fresnel zone plate lenses. The new process, based on the double patterning technique, has enabled us to fabricate high quality gold zone plates with 12 nm outer zones. Testing of the zone plate with the full-field transmission x-ray microscope, XM-1, in Berkeley, showed that the lens clearly resolved 12 nm lines and spaces. This result represents a significant step towards 10 nm resolution and beyond.

  20. Neotectonic map of Syria and some aspects of Late Cenozoic evolution of the northwestern boundary zone of the Arabian plate

    NASA Astrophysics Data System (ADS)

    Rukieh, M.; Trifonov, V. G.; Dodonov, A. E.; Minini, H.; Ammar, O.; Ivanova, T. P.; Zaza, T.; Yusef, A.; Al-Shara, M.; Jobaili, Y.

    2005-09-01

    The neotectonic map of Syria, 1:500,000, was compiled by the authors in 2003-2004. The map shows tectonic features formed or continued to develop during the Neogene and Quaternary in Syria and adjacent territories, including the Mediterranean realm. The neotectonic structure of the region was formed as a result of three phases of deformation. During the Early Miocene first phase, the Arabian plate moved along the Dead Sea-Jordan segments of the Levant (Dead Sea) transform fault zone, Roum fault and its continuation in the continental slope of the Mediterranean. The chain of the coastal anticlines in the "Arabian" side of the transform zone and the Lattaqie oblique (sinistral-thrust) boundary fault zone in the north were formed under the NNW-trending compression. The Lattaqie zone continued by the Cyprus arc in the west and by the Taurus (Bitlis) thrust in the east and further by the Main Thrust of the Zagros. After "quiet" (for Syria) epoch of the Middle Miocene when the Arabian plate moved to the NE, during the Late Miocene second phase of deformation, the Arabian plate moved again to the NNW along the same transform boundary. But a part of the Late Miocene plate motion (up to 20 km) resulted by shortening in the Anti-Leban-Palmyride fold-thrust belt that separated the Aleppo block from the main part of the Arabian plate. During the Pliocene-Quaternary third phase of deformation, the recent structural pattern of the Levant zone was formed in Lebanon and the northwestern Syria. At the same time, the Serghaya and smaller sinistral faults branched out the Levant zone and the system of the W-E-trending convex to the south dextral faults ruptured the Palmyrides and the stable part of the Arabian plate. The total Pliocene-Quaternary sinistral offset on the young Levant zone segments and the associated faults has reached 35-40 km, like on the Dead Sea-Jordan segments of the Levant fault zone. The faults, demonstrating the Pliocene-Quaternary activity are still active now

  1. Progress in the fabrication of high aspect ratio zone plates by soft x-ray lithography.

    SciTech Connect

    Divan, R.; Mancini, D. C.; Moldovan, N. A.; Lai, B.; Assoufid, L.; Leondard, Q.; Cerrina, F.

    2002-08-13

    Soft x-ray lithography technology has been applied to fabrication of phase shifting Fresnel Zone Plate (FZP's) for hard x-rays. Effects of the exposure conditions, developing system, and electroplating process parameters on line width and aspect ratio have been analyzed. The process has been optimized and an aspect ratio of 11 has been achieved for 110 nm outermost zone width. SEM and AFM have been used for preliminary metrology of the FZPs. The FZP optical performance was characterized at 8 keV photon energy at the 2-ID-D beam line at the Advanced Photon Source. Focusing efficiencies of 23% for FZPs apertures to 100 microns and 18% for 150-micron-diameter apertures have been obtained. The parameters of the fabricated FZP are in good agreement with the predicted values.

  2. The North American Astronomical Photographic Plate Center: Phase I.

    NASA Astrophysics Data System (ADS)

    Cline, J. D.; Castelaz, M. W.; Crowley, T.; Griffin, E.; Osborn, W.

    2004-05-01

    Astronomical photographic plates constitute an important and, for the large part, unrepeatable resource for research. International pressure is mounting to preserve and catalog scientifically valuable plate collections and capture their information through digitization. At the same time, many institutions holding plates now lack the space, funds and expertise to adequately preserve this important material. In response, the Pisgah Astronomical Research Institute has established the North American Photographic Plate Center (NAPPC). NAPPC is intended as a long-term repository for direct and objective prism plate collections currently stored in North America. PARI is a natural location for such a center. It offers physically secure and abundant environmentally controlled space for plate storage as well as Internet 2 infrastructure and instrument space necessary for the eventual digitization and Internet distribution of images. Phase I of this initiative is to collect unwanted plate collections, store them in an appropriate manner, prepare catalogues of their relevant information and establish a laboratory for on-site examination or measurement of the plates. This is currently underway. Phase II will be the eventual digitization and development of a public web accessible database of images. We will describe the procedures for placing plate collections in NAPPC, the infrastructure in place for plate storage and measurement, and our preliminary plans for making the plate archive a public image library with Internet access.

  3. Non-elastic Plate Weakening at Tonga, Costa Rica and Japanese Subduction Zones

    NASA Astrophysics Data System (ADS)

    Arredondo, K.; Billen, M. I.

    2010-12-01

    Traditionally studies of plate bending in subduction zones have utilized elastic, viscous or elastic-plastic rheologies to model the deformation of subducting plates, yet they are based on averaged plate properties and do not take into account variations in plate strength. Direct measurements of plate strength at subduction zones could permit more detailed models of how plates deform during subduction and may allow differentiation between the elastic and viscous or plastic rheologies. Additionally, weakening of the subducting plate is important for understanding the degree of coupling of the surface plate to the negative buoyancy of descending slabs. To obtain quantitative measurements of changes in plate strength along profiles parallel to the trench, we use analysis of the gravity-topography admittance in three subduction zones: Tonga, Costa Rica and Japan. We show that the plate flexural rigidity decreases near and inside the trench of the Tonga and Japan subduction zones, in agreement with previous results for the Kermadec subduction zone (1). Near the trench the flexural rigidity values are consistently smaller than those predicted by an elastic rheology and the plate age (2). This degree of weakening, by up to 3 orders magnitude, suggests that the plate does not act elastically as it is subducted, possibly due to lithospheric-scale weakening by extensional faulting and plastic yielding at depth. In contrast lithospheric-scale weakening in the Costa Rica subduction zone is less clear. This may be due to the younger age of the subducting plate and the small age difference between the seamounts and surrounding plate, which limits the sensitivity of the gravity field to changes in the non-isostatic support of topographic feature. These results suggest that this technique is only applicable to older plates with large seamounts that are appreciably younger than the subducting plate. Comparison of the flexural rigidity results to the tectonic characteristics of all

  4. Zone-doubled Fresnel zone plates for high-resolution hard X-ray full-field transmission microscopy

    PubMed Central

    Vila-Comamala, Joan; Pan, Yongsheng; Lombardo, Jeffrey J.; Harris, William M.; Chiu, Wilson K. S.; David, Christian; Wang, Yuxin

    2012-01-01

    Full-field transmission X-ray microscopy is a unique non-destructive technique for three-dimensional imaging of specimens at the nanometer scale. Here, the use of zone-doubled Fresnel zone plates to achieve a spatial resolution better than 20 nm in the hard X-ray regime (8–10 keV) is reported. By obtaining a tomographic reconstruction of a Ni/YSZ solid-oxide fuel cell, the feasibility of performing three-dimensional imaging of scientifically relevant samples using such high-spatial-resolution Fresnel zone plates is demonstrated. PMID:22898949

  5. Fabrication of soft x-ray Fresnel zone plate on ultrathin membrane

    NASA Astrophysics Data System (ADS)

    Tiwari, Pragya; Mondal, Puspen; Srivastava, A. K.

    2016-05-01

    Fabrication of diffractive x-ray optics for the x-ray region requires a high lateral resolution (~100 nm) and a large thickness of the phase-shifting material (0.5-3 µm). The thickness of the phase shifting material depends upon the energy of the photons. We have optimized the exposure and developing processes for 996K poly methyl methacrylate (PMMA) of different thicknesses and have worked on adhesion issues to develop a Fresnel zone plate (FZP) structure on polyimide membrane. We discuss the effects of these fabrication steps on the FZP's fabrication and aspect ratio. Preliminary evaluation of the FZPs was done by scanning electron microscopy. The FZP focusing performance will be characterized at Indus synchrotrons.

  6. Using the gradient histogram to analyze the continuous phase plate

    NASA Astrophysics Data System (ADS)

    Yang, Chunlin

    2015-01-01

    The geometrical optical method has been used to discuss the far-field distribution characteristics of a continuous phase plate. The gradient histogram of the plate’s surface has been calculated. It has been proved that the gradient histogram can be used to show the angular spectrum of a phase plate. The gradient histogram can simplify the analysis process of the angular spectrum and describe the focal spot morphology more intuitively.

  7. Testing and Calibration of Phase Plates for JWST Optical Simulator

    NASA Technical Reports Server (NTRS)

    Gong, Qian; Chu, Jenny; Tournois, Severine; Eichhorn, William; Kubalak, David

    2011-01-01

    Three phase plates were designed to simulate the JWST segmented primary mirror wavefront at three on-orbit alignment stages: coarse phasing, intermediate phasing, and fine phasing. The purpose is to verify JWST's on-orbit wavefront sensing capability. Amongst the three stages, coarse alignment is defined to have piston error between adjacent segments being 30 m to 300 m, intermediate being 0.4 m to 10 m, and fine is below 0.4 m. The phase plates were made of fused silica, and were assembled in JWST Optical Simulator (OSIM). The piston difference was realized by the thickness difference of two adjacent segments. The two important parameters to phase plates are piston and wavefront errors. Dispersed Fringe Sensor (DFS) method was used for initial coarse piston evaluation, which is the emphasis of this paper. Point Diffraction Interferometer (PDI) is used for fine piston and wavefront error. In order to remove piston's 2 pi uncertainty with PDI, three laser wavelengths, 640nm, 660nm, and 780nm, are used for the measurement. The DHS test setup, analysis algorithm and results are presented. The phase plate design concept and its application (i.e. verifying the JWST on-orbit alignment algorithm) are described. The layout of JWST OSIM and the function of phase plates in OSIM are also addressed briefly.

  8. Testing and calibration of phase plates for JWST optical simulator

    NASA Astrophysics Data System (ADS)

    Gong, Qian; Chu, Jenny; Tournois, Severine; Eichhorn, William; Kubalak, David

    2011-10-01

    Three phase plates were designed to simulate the JWST segmented primary mirror wavefront at three on-orbit alignment stages: coarse phasing, intermediate phasing, and fine phasing. The purpose is to verify JWST's on-orbit wavefront sensing capability. Amongst the three stages, coarse alignment is defined to have piston error between adjacent segments being 30 μm to 300 μm, intermediate being 0.4 μm to 10 μm, and fine being below 0.4 μm. The phase plates were made of fused silica, and were assembled in JWST Optical Simulator (OSIM). The piston difference was realized by the thickness difference of two adjacent segments. The two important parameters to phase plates are piston and wavefront errors. Dispersed Fringe Sensor (DFS) method was used for initial coarse piston evaluation, which is the emphasis of this paper. Point Diffraction Interferometer (PDI) is used for fine piston and wavefront error. In order to remove piston's 2π uncertainty with PDI, three laser wavelengths, 640nm, 660nm, and 780nm, are used for the measurement. The DHS test setup, analysis algorithm and results are presented. The phase plate design concept and its application (i.e. verifying the JWST on-orbit alignment algorithm) are described. The layout of JWST OSIM and the function of phase plates in OSIM are also addressed briefly.

  9. Vapour phase details in the oscillatory combustion of propellants A porous plate analogue

    NASA Technical Reports Server (NTRS)

    Ramohalli, K.; Magiawala, K. R.

    1979-01-01

    A perforated porous plate burner is designed to scale up the vapor phase details in composite propellant combustion. A fuel vapor is passed through the pores and an oxidizer vapor is passed through the discrete perforations drilled in the plate. Discussion of the scale modeling of the vapor phase details in oscillatory combustion of composite propellants leads to the following conclusions: (1) the concept of a perforated porous plate analog for the composite propellant vapor phase combustion appears to be valid during oscillatory combustion as well; (2) the flame standoff distance can be conveniently determined with motion picture photography; (3) the flame standoff distance varies with the flow velocity during oscillatory combustion much the same way as during time-independent combustion; and (4) the overall structure of the combustion zone (flame) does not appear to vary too much from its time-independent structure during oscillatory combustion

  10. Finite Element Modeling of Crustal Deformation in the North American Caribbean Plate Boundary Zone

    NASA Technical Reports Server (NTRS)

    Lundgren, P.; Russo, R.

    1995-01-01

    We have developed 2-dimensional spherical shell finite element models of elastic displacement in the North American-Caribbean (NA-Ca) plate boundary zone (PBZ) in order to quantify crust and fault motions in the PBZ.

  11. Multi-pore carbon phase plate for phase-contrast transmission electron microscopy.

    PubMed

    Sannomiya, Takumi; Junesch, Juliane; Hosokawa, Fumio; Nagayama, Kuniaki; Arai, Yoshihiro; Kayama, Yoko

    2014-11-01

    A new fabrication method of carbon based phase plates for phase-contrast transmission electron microscopy is presented. This method utilizes colloidal masks to produce pores as well as disks on thin carbon membranes for phase modulation. Since no serial process is involved, carbon phase plate membranes containing hundreds of pores can be mass-produced on a large scale, which allows "disposal" of contaminated or degraded phase modulating objects after use. Due to the spherical shape of the mask colloid particles, the produced pores are perfectly circular. The pore size and distribution can be easily tuned by the mask colloid size and deposition condition. By using the stencil method, disk type phase plates can also be fabricated on a pore type phase plate. Both pore and disk type phase plates were tested by measuring amorphous samples and confirmed to convert the sinus phase contrast transfer function to the cosine shape. PMID:25129640

  12. Reconstruction of images from Gabor zone plate gamma-ray holography

    NASA Astrophysics Data System (ADS)

    Unwin, Clare E.; Rew, G. A. A.; Perks, J. R.; Beynon, T. D.; Scott, Malcolm C.

    1999-09-01

    Zone plate holography is a way of obtaining 3D images from a single exposure. Unlike conventional holography, coherent radiation sources are not required. Gama ray zone plate holography can be used to image gamma rays emitted by radiopharmaceuticals used in nuclear medicine. This work concerns the computer based reconstruction of gamma ray holograms. Reconstruction algorithms including correlation and Wiener filtering are described. The images obtained using the different methods are compared.

  13. Dynamic Linkages Between the Transition Zone & Surface Plate Motions in 2D Models of Subduction

    NASA Astrophysics Data System (ADS)

    Arredondo, K.; Billen, M. I.

    2013-12-01

    While slab pull is considered the dominant force controlling plate motion and speed, its magnitude is controlled by slab behavior in the mantle, where tomographic studies show a wide range of possibilities from direct penetration to folding, or stagnation directly above the lower mantle (e.g. Fukao et al., 2009). Geodynamic studies have investigated various parameters, such as plate age and two phase transitions, to recreate observed behavior (e.g. Běhounková and Cízková, 2008). However, past geodynamic models have left out known slab characteristics that may have a large impact on slab behavior and our understanding of subduction processes. Mineral experiments and seismic observations have indicated the existence of additional phase transitions in the mantle transition zone that may produce buoyancy forces large enough to affect the descent of a subducting slab (e.g. Ricard et al., 2005). The current study systematically tests different common assumptions used in geodynamic models: kinematic versus free-slip boundary conditions, the effects of adiabatic heating, viscous dissipation and latent heat, compositional layering and a more complete suite of phase transitions. Final models have a complete energy equation, with eclogite, harzburgite and pyrolite lithosphere compositional layers, and seven composition-dependent phase transitions within the olivine, pyroxene and garnet polymorph minerals. Results show important feedback loops between different assumptions and new behavior from the most complete models. Kinematic models show slab weakening or breaking above the 660 km boundary and between compositional layers. The behavior in dynamic models with a free-moving trench and overriding plate is compared to the more commonly found kinematic models. The new behavior may have important implications for the depth distribution of deep earthquakes within the slab. Though the thermodynamic parameters of certain phase transitions may be uncertain, their presence and

  14. Axisymmetric deformation of plates and shells with phase trasformations under thermal cycling

    NASA Astrophysics Data System (ADS)

    Shkutin, L. I.

    2008-03-01

    A mathematical formulation is given of nonlinear axisymmetric buckling problems for plates and shells in the two-phase zones of austenite-to-martensite transformation. Numerical solutions of the direct-and inverse-transformation problems are used to construct hysteresis loops for thermomechanically cycled, pressure-loaded circular plates and shallow spherical domes of titanium nickelide (NiTi) alloy. It is shown that dynamic instability of the dome deformation process can occur during transformation under loads notably lower than the upper critical values for the isothermal states of the material outside the transformation zone. A theoretical analysis gives external loads below which the dome remains stable in the thermally cycled material with phase transformations.

  15. The North America - South America plate boundary zone: new elements for a geodynamic model

    NASA Astrophysics Data System (ADS)

    Roest, W. R.; Pichot, T.; Patriat, M.; Westbrook, G. K.; Gutscher, M.

    2011-12-01

    The location and functioning of the North America - South America plate boundary zone remain unknown, despite significant past efforts to decipher its precise position and the associated deformation. The Barracuda Ridge and the Tiburon Rise, two major oceanic basement ridges, are situated at the western end of this diffuse plate-boundary zone, where they enter the subduction zone beneath the Lesser Antilles island arc. The deformation of these features, and the intervening sedimentary basins and their stratigraphy record the history of NoAM-SoAM motion in this area. Kinematic studies based on reconstruction of past plate motions and GPS measurements predict small convergence during the Tertiary in the western part of this boundary zone, between the Marathon and Fifteen Twenty fracture zones. However, the differences between the different models remains too large to predict the NoAM-SoAM relative motions in this area confidently, as small changes in the postions of their rotation poles have major consequences for the expected distribution of deformation, because of their proximity to the area. Recent geophysical data acquired in this region has enabled us to locate the major structural features, and to propose an improved timing of the deformation. Seismic lines confirm the transpressional tectonic regime over a zone that is about 250 km wide, between the Barracuda Trough and the Tiburon Rise. The geodynamic situation is complicated by the fact that the deformation in the area of the Tiburon Rise and the Barracuda Ridge is clearly influenced by the flexural bulge of the active subduction zone, which uplifts the western ends of both ridges and provides a distinct western boundary to the Tiburon sedimentary basin, a trough situated between them. We have attempted to distinguish the influence of both the NoAM-SoAM convergence and the subduction process. In the North Atlantic west of Iberia, an apparently similar diffuse plate boundary zone between Europe and Africa

  16. Investigating Transition Zone Thickness Variation under the Arabian Plate: Evidence Lacking for Deep Mantle Upwellings

    NASA Astrophysics Data System (ADS)

    Juliá, J.; Tang, Z.; Mai, P. M.; Zahran, H.

    2014-12-01

    Cenozoic volcanic outcrops in Arabia - locally known as harrats - span more than 2000 km along the western half of the Arabian plate, from eastern Yemen to southern Syria. The magmatism is bimodal in character, with older volcanics (30 to 20 My) being tholeiitic-to-transitional and paralleling the Red Sea margin, and younger volcanics (12 Ma to Recent) being transitional-to-strongly-alkalic and aligning in a more north-south direction. The bimodal character has been attributed to a two-stage rifting process along the Red Sea, where the old volcanics would have produced from shallow sources related to an initial passive rifting stage, and young volcanics would have originated from one or more deep-seated mantle plumes driving present active rifting. Early models suggested the harrats would have resulted from either lateral flow from the Afar plume in Ethiopia, or more locally from a separate mantle plume directly located under the shield. Most recently, tomographic images of the Arabian mantle have suggested the northern harrats could be resulting from flow originating at a deep plume under Jordan. In this work, we investigate the location of deep mantle plumes under the Arabian plate by mapping transition zone thickness with teleseismic receiver functions. The transition zone is bounded by seismic discontinuities, nominally at 410 and 660 km depth, originating from phase transitions in the olivine-normative component of the mantle. The precise depth of the discontinuities is strongly dependent on temperature and, due to the opposing signs of the corresponding Clapeyron slopes, positive temperature anomalies are expected to result in thinning of the transition zone. Our dataset consists of ~5000 low-frequency (fc < 0.25 Hz) receiver function waveforms obtained at ~110 broadband stations belonging to a number of permanent and temporary seismic networks in the region. The receiver functions were migrated to depth and stacked along a ~2000 km long record section

  17. Guided wave phased array beamforming and imaging in composite plates.

    PubMed

    Yu, Lingyu; Tian, Zhenhua

    2016-05-01

    This paper describes phased array beamforming using guided waves in anisotropic composite plates. A generic phased array algorithm is presented, in which direction dependent guided wave parameters and the energy skew effect are considered. This beamforming at an angular direction is achieved based on the classic delay-and-sum principle by applying phase delays to signals received at array elements and adding up the delayed signals. The phase delays are determined with the goal to maximize the array output at the desired direction and minimize it otherwise. For array characterization, the beam pattern of rectangular grid arrays in composite plates is derived. In addition to the beam pattern, the beamforming factor in terms of wavenumber distribution is defined to provide intrinsic explanations for phased array beamforming. The beamforming and damage detection in a composite plate are demonstrated using rectangular grid arrays made by a non-contact scanning laser Doppler vibrometer. Detection images of the composite plate with multiple surface defects at various directions are obtained. The results show that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures. PMID:26907891

  18. Conformal dome correction with counterrotating phase plates

    NASA Astrophysics Data System (ADS)

    Sparrold, Scott W.; Mills, James P.; Knapp, David J.; Ellis, Kenneth S.; Mitchell, Thomas A.; Manhart, Paul K.

    2000-07-01

    Windows and domes that are shaped to aerodynamic requirements can increase range and speed for the host platform. This class of optical systems is referred to as conformal optics. The solution discussed here is intended for conformal missile systems having gimbals that point the optical line of sight through different parts of the dome. A conformal dome induces large amounts of varying aberration, tens to hundreds of waves across gimbal angle, and therefore requires dynamic correction. Space is very constricted in missile sensors, and it is therefore highly desirable to limit the number of motors used for aberration correction. This paper describes the performance of a new class of optical systems that employ counterrotating phase prisms to correct conformal dome aberrations while gimbaling the optical system. The phase surfaces on the prisms are described by Zernike circular polynomials. Since the shear across the phase surfaces is rotational, the only aberrations that are generated are those without rotational symmetry, such as tilt, coma, or astigmatism. Using this approach, CODE VTM was used to analyze and design a compact, high-performance conformal optical system.

  19. Methods for testing Zernike phase plates and a report on silicon-based phase plates with reduced charging and improved ageing characteristics

    PubMed Central

    Marko, Michael; Meng, Xing; Hsieh, Chyongere; Roussie, James; Striemer, Christopher

    2013-01-01

    Imaging with Zernike phase plates is increasingly being used in cryo-TEM tomography and cryo-EM single-particle applications. However, rapid ageing of the phase plates, together with the cost and effort in producing them, present serious obstacles to widespread adoption. We are experimenting with phase plates based on silicon chips that have thin windows; such phase plates could be mass-produced and made available at moderate cost. The windows are coated with conductive layers to reduce charging, and this considerably extends the useful life of the phase plates compared to traditional pure-carbon phase plates. However, a compromise must be reached between robustness and transmission through the phase-plate film. Details are given on testing phase-plate performance by means of imaging an amorphous thin film and evaluating the power spectra of the images. PMID:23994351

  20. Subcrustal earthquakes in the plate boundary zone of New Zealand's South Island

    NASA Astrophysics Data System (ADS)

    Boese, C. M.; Stern, T. A.; Townend, J.; Sheehan, A. F.; Molnar, P. H.; Collins, J. A.; Karalliyadda, S.; Bourguignon, S.; Bannister, S. C.

    2012-12-01

    Sporadic, intermediate-depth earthquakes have been observed for ~40 years in the vicinity of the Alpine Fault, a 460 km-long transpressive fault forming the western boundary of the Southern Alps. The Alpine Fault represents the plate boundary between the Australian and Pacific Plates in New Zealand and links two subduction zones of opposite polarity in the North and South. Several earthquakes at depths of 59-85 km have been recorded by the Southern Alps Microearthquake Borehole Array (SAMBA) since its deployment in November 2008. Due to large numbers of impulsive phase arrivals, focal mechanisms were obtained for these events during routine processing. In 2009 and early 2010, several additional temporary seismometer networks were operating in the central Southern Alps (Alpine Fault Array ALFA, Deep Fault Drilling Project 2010 DFDP10) and the offshore region west of the South Island (Marine Observations of Anisotropy Near Aotearoa MOANA). To gain more insight about the cause and mechanism of these deep events, a comprehensive analysis has been performed incorporating data from all available instruments. Accurate hypocentres of 22 earthquakes (ML<4) and focal mechanisms of at least 14 events have been obtained. The focal mechanisms reveal that reverse faulting predominates at depth in the continental collision zone between the Pacific and Australian Plates. The intermediate-depth events occur below the Moho discontinuity, which has been mapped in detail using wide-angle reflection/refraction data obtained during the South Island Geophysical Transect (SIGHT) project in 1995/96. Although the cause for these subcrustal earthquakes is not yet clear, they have previously been interpreted to result from intra-continental subduction (Reyners 1987), high shear-strain gradients due to depressed geotherms and viscous deformation of mantle lithosphere (Kohler and Eberhart-Phillips 2003). On the basis of the locations and mechanisms obtained using SAMBA, we have argued that

  1. The fate of the downgoing oceanic plate: Insight from the Northern Cascadia subduction zone

    NASA Astrophysics Data System (ADS)

    Piana Agostinetti, Nicola; Miller, Meghan S.

    2014-12-01

    In this study, we use teleseismic receiver function analysis to image the seismic structure of the Juan de Fuca oceanic plate during its subduction beneath the North American plate. Seismic data have been recorded at 58 seismic stations deployed along the northern Cascadia subduction zone. Harmonic decomposition of the receiver function data-set along a trench-normal profile allows us to image both the isotropic and the anisotropic structure of the plate (slab). Our images highlight the presence of a highly anisotropic region at 40-70 km depths across the Cascadia subduction zone. The detected seismic anisotropy is interpreted to be related to both metamorphic facies (e.g. blueschists) and fluid released during the dehydration of the subducting mantle. The processes of dehydration and metamorphism produce the variations of the seismic properties within each lithologic unit that constitutes the subducted slab, i.e. basalts, gabbro layer and upper mantle, as the oceanic plate sinks in the upper mantle. Such variations make it almost impossible to recognize the “plate boundary” as a characteristic “velocity-jump” at depth (neither positive nor negative) along the Cascadia subduction zone. Based on the comparative interpretation of both the isotropic and the anisotropic structures retrieved, we propose a 4-stage model of the evolution of the Juan de Fuca oceanic plate during its subduction beneath the North American plate.

  2. A high-resolution local network study of the Nazca plate Wadati-Benioff zone under western Argentina

    NASA Technical Reports Server (NTRS)

    Smalley, Robert F., Jr.; Isacks, Bryan L.

    1987-01-01

    Seismic data, recorded by INPRES telemetered network located above one of the subhorizontal segments of the subducted Nazca plate Wadati-Benioff zone beneath western Argentina, were analyzed to determine the zone's fine structure. The depth of the center and the thickness of the subhorizontal Wadati-Benioff zone beneath the network were calculated to be about 107 km and about 20 km, respectively, with most of the seismogenic zone concentrated in a region about 12 km thick. The Nazca plate is interpreted to be in a state of down-dip tension and to be decoupled from the overriding South American plate by a weak zone of asthenospheric or shear-heated material. The South American plate is estimated to be 80 km thick, based on the location of the subducted Nazca plate and an inferred decoupling zone between the plates.

  3. Efficient alignment scheme for zone-plates-based transmission soft X-ray microscope

    NASA Astrophysics Data System (ADS)

    Lim, Jun; Shin, Hyun-Joon; Hong, Chung Ki

    2010-12-01

    Alignment and operation of a zone-plate (ZP)-based transmission soft X-ray microscope (TXM) is difficult and time consuming, especially when the TXM has no dedicated X-ray source. We introduce here an efficient TXM alignment scheme. The TXM employed is a simple in-situ-experiment-capable setup. It includes ultrahigh-vacuum (UHV)-compatible conflat flanges and is mountable in tandem with any soft X-ray synchrotron radiation beamlines. Obtaining zeroth- and first-order diffracted (condenser-zone-plate [CZP]-focused) beams simultaneously by means of the objective zone plate (OZP) is the most essential step in the alignment scheme. We were able to acquire, in one hour at a radiation wavelength of 2.49 nm, an image of 50 nm spatial resolution.

  4. Absolute plate motions since 130 Ma constrained by subduction zone kinematics

    NASA Astrophysics Data System (ADS)

    Williams, Simon; Flament, Nicolas; Dietmar Müller, R.; Butterworth, Nathaniel

    2015-05-01

    The absolute motions of the lithospheric plates relative to the Earth's deep interior are commonly constrained using observations from paleomagnetism and age-progressive seamount trails. In contrast, an absolute plate motion (APM) model linking surface plate motions to subducted slab remnants mapped from seismic tomography has recently been proposed. Absolute plate motion models (or "reference frames") derived using different methodologies, different subsets of hotspots, or differing assumptions of hotspot motion, have contrasting implications for parameters that describe the long term state of the plate-mantle system, such as the balance between advance and retreat of subduction zones, plate velocities, and net lithospheric rotation. Previous studies of contemporary plate motions have used subduction zone kinematics as a constraint on the most likely APM model. Here we use a relative plate motion model to compute these values for the last 130 Myr for a range of alternative reference frames, and quantitatively compare the results. We find that hotspot and tomographic slab-remnant reference frames yield similar results for the last 70 Myr. For the 130-70 Ma period, where hotspot reference frames are less well constrained, these models yield a much more dispersed distribution of slab advance and retreat velocities. By contrast, plate motions calculated using the slab-remnant reference frame, or using a reference frame designed to minimise net rotation, yield more consistent subduction zone kinematics for times older than 70 Ma. Introducing the global optimisation of trench migration characteristics as a key criterion in the construction of APM models forms the foundation of a new method of constraining APMs (and in particular paleolongitude) in deep geological time.

  5. Kinematics to dynamics in the New Zealand plate-boundary zone

    NASA Astrophysics Data System (ADS)

    Lamb, S. H.

    2013-12-01

    New Zealand straddles the boundary between the Australian and Pacific plate, with a transition from subduction of Pacific oceanic lithosphere beneath North Island, to oblique continental collision in South Island. Cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation in a zone up to 250 km wide, with displacements on individual faults up to 100s of kilometres. Active deformation must be driven by a combination of plate-boundary forces and internal buoyancy forces. I use a compilation of seismic reflection/refraction studies and high quality receiver function analyses, together with simple Airy isostasy, to determine regional crustal and mantle structure. Integration of the vertical normal stress to the base of the deforming layer yields the buoyancy stress. Horizontal gradients of this can be compared with horizontal gradients of strain rate, using the method of England & Molnar (1997), in the context of a simple thin sheet model of deformation. Thus, if deformation is that of a Newtonian fluid, then appropriate combinations of the horizontal gradients of vorticity and dilatation are related to gradients of buoyancy stress by the fluid viscosity. However, the short term geodetic deformation is strongly biased by elastic strain accumulation related to locking on the plate interface, and cannot be used to determine the plate-boundary velocity field averaged over many seismic cycles (see Lamb & Smith 2013). Therefore, I derive here a velocity field for the plate-boundary zone, which is representative of deformation over tens of thousands of years. This is based on an inversion of fault slip, strain rate azimuth and paleomagnetic data, in the context of the short term relative plate motions, solved in a network of triangles spanning the plate-boundary, using the method of Lamb (2000). A comparison of gradients of buoyancy stress with the appropriate combinations of gradients of vorticity and dilatation shows that deformation in

  6. Fresnel zone plates for Achromatic Imaging Survey of X-ray sources

    SciTech Connect

    Palit, Sourav; Chakrabarti, S. K.; Debnath, D.; Yadav, Vipin; Nandi, Anuj

    2008-10-08

    A telescope with Fresnel Zone Plates has been contemplated to be an excellent imaging mask in X-rays and gamma-rays for quite some time. With a proper choice of zone plate material, spacing and an appropriate readout system it is possible to achieve any theoretical angular resolution. We provide the results of numerical simulations of how a large number of X-ray sources could be imaged at a high resolution. We believe that such an imager would be an excellent tool for a future survey mission for X-ray and gamma-ray sources which we propose.

  7. Interplate coupling at oblique subduction zones: influence on upper plate erosion.

    NASA Astrophysics Data System (ADS)

    Malatesta, Cristina; Gerya, Taras; Crispini, Laura; Federico, Laura; Scambelluri, Marco; Capponi, Giovanni

    2014-05-01

    In active subduction zones, when the converging plates cannot slip freely past each other, "plate coupling" occurs. The moving subducting slab and therefore the coupling/decoupling relationship between plates control both short- and long-term deformation of the upper plate. Short-term deformation is dominantly elastic, occurs at human timescales and can be directly associated with earthquakes. Long-term deformation is cumulative, permanent and prevails at the geological timescale (Hoffman-Rothe et al., 2006, Springer Berlin Heidelberg). Here we used 3D numerical simulations to test oblique subduction zones and to investigate: 1) how long-term deformation and coupling relationship vary along the trench-axis; 2) how this relationship influences erosion and down-drag of upper plate material. Our models are based on thermo-mechanical equations solved with finite differences method and marker-in-cell techniques combined with a multigrid approach (Gerya, 2010, Cambridge Univ. Press). The reference model simulates an intraoceanic subduction close to the continental margin (Malatesta et al., 2013, Nature Communications, 4:2456 DOI:10.1038/ncomms3456). The oceanic crust is layered with a 5-km-thick layer of gabbro overlain by a 3-km-thick layer of basalt. The ocean floor is covered by 1-km-thick sediments. Plates move with a total velocity of 3.15 cm/yr; the oblique convergence is obtained using velocity vectors that form an angle of 45° with the initial starting point of subduction (weak zone in the lithosphere). After initiation of plate convergence, part of sediments on top of the incoming plate enters the subduction zone and is buried; another part is suddenly transferred along strike at shallow depths and along the subducting slab according to the direction of the along-trench velocity component of subduction. The lateral migration of sediment causes the evolution of the trench along its strike from sediment-poor to sediment-rich. As soon as subduction starts, where

  8. Kinematics to dynamics in the New Zealand plate-boundary zone

    NASA Astrophysics Data System (ADS)

    Lamb, Simon

    2014-05-01

    New Zealand straddles the boundary between the Australian and Pacific plate, with a transition from subduction of Pacific plate oceanic lithosphere in the North, beneath North Island to oblique continental collision in South Island. Cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation in a zone up to 250 km wide, with displacements on individual faults up to 100s of kilometres. Here, I use a compilation of seismic reflection/refraction studies and high quality receiver function analyses, together with simple Airy isostasy, to determine the regional crustal and mantle structure. The buoyancy stress in the deforming layer is calculated by integrating the vertical normal stress with depth. This, in combination with plate-boundary stresses, must drive deformation. Horizontal gradients of buoyancy stress can be compared with horizontal gradients of strain rate, using the method of England & Molnar (1997), in the context of a simple thin sheet model of lithospheric deformation. I derive a velocity field for the New Zealand plate-boundary zone, using the method of Lamb (2000). This is representative of deformation over tens of thousands of years, based on fault slip, strain rate azimuth and paleomagnetic data, in the context of the short term relative plate motions. Comparison of appropriate combinations of horizontal gradients of vorticity and dilatation with horizontal gradients of buoyancy stress shows that deformation has some of the features of a Newtonian fluid. In detail, the minima in buoyancy stress, calculated from the vertical density structure, are offset horizontally from that calculated from gradients of strain rate, suggesting strong lateral contrasts in viscosity if deformation is strongly coupled at all levels in the lithosphere, with viscosities in the range 1 - 10 x 10**21 Pa s. However, subduction of Pacific plate lithosphere along the Hikurangi margin, and evidence for underthrusting beneath the Southern Alps

  9. Phase plate technology for laser marking of magnetic discs

    DOEpatents

    Neuman, B.; Honig, J.; Hackel, L.; Dane, C.B.; Dixit, S.

    1998-10-27

    An advanced design for a phase plate enables the distribution of spots in arbitrarily shaped patterns with very high uniformity and with a continuously or near-continuously varying phase pattern. A continuous phase pattern eliminates large phase jumps typically expected in a grating that provides arbitrary shapes. Large phase jumps increase scattered light outside of the desired pattern, reduce efficiency and can make the grating difficult to manufacture. When manufacturing capabilities preclude producing a fully continuous grating, the present design can be easily adapted to minimize manufacturing errors and maintain high efficiencies. This continuous grating is significantly more efficient than previously described Dammann gratings, offers much more flexibility in generating spot patterns and is easier to manufacture and replicate than a multi-level phase grating. 3 figs.

  10. Phase plate technology for laser marking of magnetic discs

    DOEpatents

    Neuman, Bill; Honig, John; Hackel, Lloyd; Dane, C. Brent; Dixit, Shamasundar

    1998-01-01

    An advanced design for a phase plate enables the distribution of spots in arbitrarily shaped patterns with very high uniformity and with a continuously or near-continuously varying phase pattern. A continuous phase pattern eliminates large phase jumps typically expected in a grating that provides arbitrary shapes. Large phase jumps increase scattered light outside of the desired pattern, reduce efficiency and can make the grating difficult to manufacture. When manufacturing capabilities preclude producing a fully continuous grating, the present design can be easily adapted to minimize manufacturing errors and maintain high efficiencies. This continuous grating is significantly more efficient than previously described Dammann gratings, offers much more flexibility in generating spot patterns and is easier to manufacture and replicate than a multi-level phase grating.

  11. Zone plate tilt study in transmission x-ray microscope system at 8-11 keV

    NASA Astrophysics Data System (ADS)

    Chao, Fu-Han; Yin, Gung-Chian; Liang, Keng S.; Lai, Yin-Chieh

    2009-08-01

    Zone plate [1] has been used as a focal lens in transmission X-ray microscope (TXM) optical system in recent decades [2, 3]. In TXM of NSRRC[4,5], the thickness of zone plate is about 900nm and the width of its out most zones is 50nm, which has a high aspect ratio 18. When zone plate is tilted, the image quality will be affected by aberration. Since the aspect ratio of zone plate is large, for incident beam, the shape of zone plate's transmission function will look different when zone plate is tilted. The both experimental and simulation result will be shown in this present. A five axes stage is designed and manufactured for the zone plate holder for three dimensional movement, tip and tilt. According to Fourier theory, we can calculate the wave distribution on image plane, if we know the original wave function, the distances between each element, and the transparencies of the sample and zone plate. A parallel simulation process code in MATLAB is developed in workstation cluster with up to 128Gbytes memory. The effects of aberration generated by tilt effect are compared from the experimental data and simulation result. A maximum tilt angle within the acceptable image quality is calculated by simulation and will be verified by experiment.

  12. Development of a two-phase cold plate

    NASA Astrophysics Data System (ADS)

    Miyazaki, Y.; Furukawa, M.; Ishii, Y.; Shigehara, M.; Komori, M.; Mimura, K.; Oshima, S.

    1990-03-01

    A two-phase cold plate using evaporators of grooved double-pipe type was tested in order to examine its heat transfer and hydrodynamic characteristics under practical operating conditions. Under a uniform heat load, excellent temperature uniformity of the cold plate was obtained. Under an uneven heat load, however, the temperature distributions were not uniform; they were high in active areas and low in inactive areas. It seems to be due to ineffective liquid flow through inactive pipes, which causes liquid shortage in active tubes and over-cooling by sub-cooled liquid in inactive tubes. Parallel operations with two cold plates were performed successfully, demonstrating that both temperatures were kept at the same level even under different heat loads. In a certain operating condition, the individual flow rate of the two cold plates was observed to oscillate symmetrically to each other, while total flow rate was kept constant and no anomalous behavior on heat transfer was induced. Through the tests, a design approach for the cold plate from the viewpoint of a loop control technology was obtained.

  13. Earthquake Production by Subduction Zones is Not Linear in Relative Plate Velocity

    NASA Astrophysics Data System (ADS)

    Bird, P.; Kagan, Y. Y.; Jackson, D. D.; Schoenberg, F. P.; Werner, M. J.

    2007-12-01

    The ratio of \\{long-term-average seismic moment production per unit length of plate boundary\\} to \\{relative plate velocity\\} is determined by the "coupled thickness" of seismogenic lithosphere, and also by elastic moduli and geometric factors that are fairly well known. It is generally assumed that coupled thickness is constant within a given class of plate boundary, such as Bird's [2003, G3]: CCB Continental Convergent Boundary, CRB Continental Rift Boundary, CTF Continental Transform Fault, OCB Oceanic Convergent Boundary, OSR Oceanic Spreading Ridge, OTF Oceanic Transform Fault, or SUB Subduction zone. However, Bird et al. [2002, Geodyn. Ser.] and Bird & Kagan [2004, BSSA] found two exceptions: OSR and OTF both have greater coupled thickness at low relative plate velocities. We test for variation of coupled thickness with relative plate velocity in each of the 7 classes of plate boundary. We use shallow (<70 km) earthquakes from the Harvard CMT catalog, 1982.01.01-2007.03.31, above magnitude MW threshold of 5.51 or 5.66. In order to reduce the influence of aftershock swarms, we estimate the probability of independence of each earthquake according to the likelihood stochastic declustering method of Kagan & Jackson [1991; GJI] and use this as a weight. We use the algorithm of Bird & Kagan [2004, BSSA] to assign 95% of shallow earthquakes to plate boundary steps and plate boundary classes, rejecting all earthquakes that fall into one of the 13 orogens of Bird [2003, G3]. We order the plate-boundary steps outside orogens in each class by relative plate velocity according to the PB2002 model of Bird [2003]. Then, we plot cumulative earthquake count as a function of cumulative model tectonic moment (assuming constant coupled thickness and other parameters within each plate boundary class). The null hypothesis is a linear relation; we use 2 measures (Kolmogorov-Smirnov, and Cramer-von Mises) to quantify departures from this line. We use 10,000 simulations of each

  14. High-Efficiency Gold Fresnel Zone Plates for Multi-keV X-rays

    NASA Astrophysics Data System (ADS)

    Gorelick, S.; Vila-Comamala, J.; Guzenko, V. A.; Barrett, R.; Salomé, M.; David, C.

    2011-09-01

    We report a direct e-beam writing process of Fresnel zone plates (FZPs) using thick layers of PMMA resist as electroplating molds. We used 100-kV electron beam lithography to directly expose thick PMMA layers, which were later used as plating molds without intermediate etching steps. High-quality 500-nm- and 1-μm-thick Au FZPs with outermost zone widths down to 50-nm and 70-nm, respectively, and with diameters up to 600 μm were fabricated. In this paper we present the details of the optimized fabrication process, such as development times, developer, dose tables, and line shrinkages required to obtain the desired zone widths and gaps between the zones. The diffraction efficiencies of the fabricated FZPs were measured for a wide range of x-ray energies (2.8-13.2 keV) showing excellent values up to 65-75% of the theoretical maximum, reflecting the good quality of the FZPs. Spatially resolved diffraction efficiency measurements indicate the uniformity of the zone plates and lack of defects.

  15. Strain modeling of attachment zones developed between brittle and ductile crust at wrenching plate boundaries

    NASA Astrophysics Data System (ADS)

    Teyssier, C.; Tikoff, B.; Weber, J.

    2001-12-01

    Using strain modeling we analyze the ductile deformation beneath rigid upper crustal blocks that rotate and translate in wrench zones. We define the zone of deformation as an "attachment zone" and assume strain continuity between the wrench shearing in the ductile crust and the horizontal shearing induced by the rotation/translation of rigid blocks. For reasonable amounts of rotation/translation of rigid blocks and reasonable thicknesses of attachment zones, the orientation and shape of the finite strain ellipsoids within attachment zones are calculated, and the orientation of planar and linear fabrics are predicted. Attachment zones beneath rotating blocks should display radiating foliation and concentric lineations; if rotation of rigid blocks is driven from below, deformation in the attachment zone is dominated by the wrench component, altering significantly the radiating and concentric patterns of foliation and lineation. Attachment zones beneath translating blocks display a wide range of foliation orientations, with steep foliations below the central part of rigid blocks, and gently dipping foliations toward the margins. Below the upper crustal strike-slip faults, foliation is shallowly dipping, strain intensity is maximum, and there is an abrupt reversal of sense of shear across a presumed discontinuity. The linear belt of greenschist-grade metamorphic rocks in Trinidad's Northern Ranges and eastern Venezuela's Paria Peninsula is a candidate for an exhumed attachment zone developed beneath translating upper crustal blocks during Neogene highly oblique convergence between the Caribbean and South America plates.

  16. Volta potential phase plate for in-focus phase contrast transmission electron microscopy

    PubMed Central

    Danev, Radostin; Buijsse, Bart; Khoshouei, Maryam; Plitzko, Jürgen M.; Baumeister, Wolfgang

    2014-01-01

    We describe a phase plate for transmission electron microscopy taking advantage of a hitherto-unknown phenomenon, namely a beam-induced Volta potential on the surface of a continuous thin film. The Volta potential is negative, indicating that it is not caused by beam-induced electrostatic charging. The film must be heated to ∼200 °C to prevent contamination and enable the Volta potential effect. The phase shift is created “on the fly” by the central diffraction beam eliminating the need for precise phase plate alignment. Images acquired with the Volta phase plate (VPP) show higher contrast and unlike Zernike phase plate images no fringing artifacts. Following installation into the microscope, the VPP has an initial settling time of about a week after which the phase shift behavior becomes stable. The VPP has a long service life and has been used for more than 6 mo without noticeable degradation in performance. The mechanism underlying the VPP is the same as the one responsible for the degradation over time of the performance of thin-film Zernike phase plates, but in the VPP it is used in a constructive way. The exact physics and/or chemistry behind the process causing the Volta potential are not fully understood, but experimental evidence suggests that radiation-induced surface modification combined with a chemical equilibrium between the surface and residual gases in the vacuum play an important role. PMID:25331897

  17. Breaking into the Plate: Seismic and Hydroacoustic Analysis of a 7.6 Mw Oceanic Fracture Zone Earthquake Adjacent to the Central Indian Ridge Plate Boundary

    NASA Astrophysics Data System (ADS)

    Bohnenstiehl, D. R.; Tolstoy, M.; Chapp, E.

    2003-12-01

    Where oceanic spreading segments are offset laterally from one another, the differential motion of the plates is accommodated by strike-slip motion along ridge-perpendicular transform faults. Off-axis from the ridge-transform intersection, no differential motion is require, and the fracture zone trace is thought to be inactive except where reactivated by intra-plate stresses. On 15 July 2003, an earthquake with a magnitude of 7.6 Mw occurred near the northern Central Indian Ridge (CIR), the divergent boundary separating the Somalian plate from the Indian and Australian plates. The size of this event places it within the 99th quantile of magnitude for shallow (< 40 km depth) strike-slip events (null axis plunge >45 deg) within the global Harvard CMT catalog. The earthquake's epicenter is near 2.5 deg S, 68.33 deg E, where the CIR is marked by a series of short (<100 km long) right-stepping transforms that offset the northwest trending spreading segments (20 mm/yr). Seismic signals associated with the mainshock and its largest aftershocks were recorded well by land-based seismic networks. Regional seismic phases (Pn, Sn), as well oceanic T-waves, where also recorded at an IMS hydroacoustic station to the north of the Diego Garcia atoll. T-wave signals recorded at Diego Garcia were cross correlated to determine accurate travel time differences. These traveltime differences were used in a plane wave fitting inversion to determine the horizontal slowness components and estimate the back azimuth to the epicenter. Aftershock locations are derived using the azimuthal information and Pn-T traveltime differences. Together, the seismically- and hydroacoustically-derived epicenters show a linear band of aftershocks extending more than 200 km along the off-axis trace of a right stepping transform. We interpret these aftershock events as delineating the length of the mainshock rupture. As the well-constrain hypocenter of the mainshock lies near the western edge of this

  18. Achromatic phase shifts utilizing dielectric plates for nulling interferometery

    NASA Astrophysics Data System (ADS)

    Morgan, R. M.; Burge, J. M.

    1998-12-01

    Schemes for detecting planets around other stars using interferometery have been developed which rely on a half wave phase delay to shift the central constructive fringe of an interferometer to a deep, destructive null fringe. To achieve the sensitivity and spectroscopy desired for exo-planets observations, such a null must be achromatic over a broad spectral region. One method for creating such a half wave phase delay achromatically involves the use of pairs of dielectric, plane parallel plates, analogous to the use of two types of glass in an achromatic lens. An analysis of the technique is presented with solutions using single plates to achieve null fringes to a cancellation of 10 exp -4 in the visible, near infrared, and mid infrared for null. Solutions using two matched materials show that nulls to a depth of 10 exp -6 are achievable in 2 um bands in the 7-17 um regime, or to a depth of 10 exp -5 over the entire 7-17 um band. Experimental results using a single plate of BK7 in the visible spectrum verify the technique.

  19. Microarray Cluster Analysis of Irradiated Growth Plate Zones Following Laser Microdissection

    SciTech Connect

    Damron, Timothy A. Zhang Mingliang; Pritchard, Meredith R.; Middleton, Frank A.; Horton, Jason A.; Margulies, Bryan M.; Strauss, Judith A.; Farnum, Cornelia E.; Spadaro, Joseph A.

    2009-07-01

    Purpose: Genes and pathways involved in early growth plate chondrocyte recovery after fractionated irradiation were sought as potential targets for selective radiorecovery modulation. Materials and Methods: Three groups of six 5-week male Sprague-Dawley rats underwent fractionated irradiation to the right tibiae over 5 days, totaling 17.5 Gy, and then were killed at 7, 11, and 16 days after the first radiotherapy fraction. The growth plates were collected from the proximal tibiae bilaterally and subsequently underwent laser microdissection to separate reserve, perichondral, proliferative, and hypertrophic zones. Differential gene expression was analyzed between irradiated right and nonirradiated left tibia using RAE230 2.0 GeneChip microarray, compared between zones and time points and subjected to functional pathway cluster analysis with real-time polymerase chain reaction to confirm selected results. Results: Each zone had a number of pathways showing enrichment after the pattern of hypothesized importance to growth plate recovery, yet few met the strictest criteria. The proliferative and hypertrophic zones showed both the greatest number of genes with a 10-fold right/left change at 7 days after initiation of irradiation and enrichment of the most functional pathways involved in bone, cartilage, matrix, or skeletal development. Six genes confirmed by real-time polymerase chain reaction to have early upregulation included insulin-like growth factor 2, procollagen type I alpha 2, matrix metallopeptidase 9, parathyroid hormone receptor 1, fibromodulin, and aggrecan 1. Conclusions: Nine overlapping pathways in the proliferative and hypertrophic zones (skeletal development, ossification, bone remodeling, cartilage development, extracellular matrix structural constituent, proteinaceous extracellular matrix, collagen, extracellular matrix, and extracellular matrix part) may play key roles in early growth plate radiorecovery.

  20. Seismic evidence for deep fluid circulation in the overriding plate of subduction zones

    NASA Astrophysics Data System (ADS)

    Tauzin, B.; Reynard, B.; Bodin, T.; Perrillat, J. P.; Debayle, E.

    2015-12-01

    In subduction zones, non-volcanic tremors are associated with fluid circulations (Obara, 2002). Their sources are often located on the interplate boundary (Rogers and Dragert, 2003; Shelly et al, 2006; La Rocca, 2009), consistent with fluids released by the dehydration of subducted plates (Hacker et al., 2003). Reports of tremors in the overriding continental crust of several subduction zones in the world (Kao et al., 2005; Payero et al., 2008; Ide, 2012) suggest fluid circulation at shallower depths but potential fluid paths are poorly documented. Here we obtained seismic observations from receiver functions that evidence the close association between the shallow tremor zone, electrical conductivity, and tectonic features of the Cascadia overriding plate. A seismic discontinuity near 15 km depth in the crust of the overriding North American plate is attributed to the Conrad discontinuity. This interface is segmented, and its interruption is spatially correlated with conductive regions and shallow swarms of seismicity and non-volcanic tremors. These observations suggest that shallow fluid circulation, tremors and seismicity are controlled by fault zones limiting blocks of accreted terranes in the overriding plate (Brudzinski and Allen, 2007). These zones constitute fluid "escape" routes that may contribute unloading fluid pressure on the megathrust. Obara, K. (2002). Science, 296, 1679-1681. Rogers, G., & Dragert, H. (2003). Science, 300, 1942-1943. Shelly, D. R., et al. (2006). Nature, 442, 188-191. La Rocca, M., et al. (2009). Science, 323, 620-623. Kao, H., et al. (2005). Nature, 436, 841-844. Payero, J. S., et al. (2008). Geophysical Research Letters, 35. Ide, S. (2012). Journal of Geophysical Research: Solid Earth, 117. Brudzinski, M. R., & Allen, R. M. (2007). Geology, 35, 907-910.

  1. Circular multilayer zone plate for high-energy x-ray nano-imaging.

    PubMed

    Koyama, Takahisa; Takano, Hidekazu; Konishi, Shigeki; Tsuji, Takuya; Takenaka, Hisataka; Ichimaru, Satoshi; Ohchi, Tadayuki; Kagoshima, Yasushi

    2012-01-01

    A circular multilayer zone plate (MZP) was fabricated and its focusing performance was evaluated using 20-keV x-rays. MoSi(2) and Si layers were alternately deposited by DC magnetron sputtering on a wire core; all the interfaces satisfied the Fresnel zone condition. The measured line spread function was converted to a point spread function by tomographic reconstruction. The results suggest that the MZP has the potential to realize the diffraction-limited resolving power, which is calculated to be 35 nm using the diffraction integral. Furthermore, scanning transmission microscopy using the MZP could resolve a 50-nm line-and-space pattern. PMID:22299960

  2. 3D numerical modeling of subduction dynamics: plate stagnation and segmentation, and crustal advection in the mantle transition zone

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Tajima, F.

    2012-04-01

    Water content in the mantle transition zone (MTZ) has been broadly debated in the Earth science community as a key issue for plate dynamics [e.g., Bercovici and Karato, 2003]. In this study, a systematic series of three-dimensional (3D) numerical simulation are performed in an attempt to verify two hypotheses for plate subduction with effects of deep water transport: (1) the small-scale behavior of subducted oceanic plate in the MTZ; and (2) the role of subducted crust in the MTZ. These hypotheses are postulated based on the seismic observations characterized by large-scale flattened high velocity anomalies (i.e., stagnant slabs) in the MTZ and discontinuity depth variations. The proposed model states that under wet conditions the subducted plate main body of peridotite (olivine rich) is abutted by subducted crustal materials (majorite rich) at the base of the MTZ. The computational domain of mantle convection is confined to 3D regional spherical-shell geometry with a thickness of 1000 km and a lateral extent of 10° × 30° in the latitudinal and longitudinal directions. A semi-dynamic model of subduction zone [Morishige et al., 2010] is applied to let the highly viscous, cold oceanic plate subduct. Weak (low-viscosity) fault zones (WFZs), which presumably correspond to the fault boundaries of large subduction earthquakes, are imposed on the top part of subducting plates. The phase transitions of olivine to wadsleyite and ringwoodite to perovskite+magnesiowüstite with Clapeyron slopes under both "dry" and "wet" conditions are considered based on recent high pressure experiments [e.g., Ohtani and Litasov, 2006]. Another recent experiment provides new evidence for lower-viscosity (weaker strength) of garnet-rich zones than the olivine dominant mantle under wet conditions [Katayama and Karato, 2008]. According to this, the effect of viscosity reduction of oceanic crust is considered under wet condition in the MTZ. Results show that there is a substantial difference

  3. Deep low-frequency earthquakes in tremor localize to the plate interface in multiple subduction zones

    USGS Publications Warehouse

    Brown, J.R.; Beroza, G.C.; Ide, S.; Ohta, K.; Shelly, D.R.; Schwartz, S.Y.; Rabbel, W.; Thorwart, M.; Kao, H.

    2009-01-01

    Deep tremor under Shikoku, Japan, consists primarily, and perhaps entirely, of swarms of low-frequency earthquakes (LFEs) that occur as shear slip on the plate interface. Although tremor is observed at other plate boundaries, the lack of cataloged low-frequency earthquakes has precluded a similar conclusion about tremor in those locales. We use a network autocorrelation approach to detect and locate LFEs within tremor recorded at three subduction zones characterized by different thermal structures and levels of interplate seismicity: southwest Japan, northern Cascadia, and Costa Rica. In each case we find that LFEs are the primary constituent of tremor and that they locate on the deep continuation of the plate boundary. This suggests that tremor in these regions shares a common mechanism and that temperature is not the primary control on such activity. Copyright 2009 by the American Geophysical Union.

  4. Observation of Wet Biological Specimen by Soft X-Ray Microscope with Zone Plates at UVSOR

    NASA Astrophysics Data System (ADS)

    Watanabe, Norio; Taniguchi, Mieko; Shimanuki, Yoshio; Sugiyama, Masaru; Ohba, Akira; Kihara, Hiroshi

    1992-11-01

    With an environmental chamber (wet cell) using polypropylene foils as windows, wet specimens were observed at a wavelength of 4.6 nm with a zone plate imaging X-ray microscope installed at the beamline 8 A of UVSOR (synchrotron radiation facility at Institute for Molecular Science, Okazaki, Japan). Images of spicule of trepang, human blood cells and cultured protoplast of plant cell stained by methyl mercury were observed with good contrast.

  5. Colorful holographic imaging reconstruction based on one thin phase plate

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Song, Qiang; Wang, Jian; Yue, Weirui; Zhang, Fang; Huang, Huijie

    2014-11-01

    One method of realizing color holographic imaging using one thin diffractive optical element (DOE) is proposed. This method can reconstruct a two-dimensional color image with one phase plate at user defined distance from DOE. For improving the resolution ratio of reproduced color images, the DOE is optimized by combining Gerchberg-Saxton algorithm and compensation algorithm. To accelerate the computational process, the Graphic Processing Unit (GPU) is used. In the end, the simulation result was analyzed to verify the validity of this method.

  6. The origin of spontaneous electrical activity at the end-plate zone.

    PubMed

    Brown, W F; Varkey, G P

    1981-12-01

    Two types of spontaneous electrical activity are present at the end-plate zone: low-voltage negative potentials that correspond to miniature end-plate potentials, and larger voltage negative-positive potentials. The electrogenic origin of the latter has been uncertain. The origin of these larger potentials was investigated in the rat phrenic nerve diaphragm preparation and in human gastrocnemius muscle just prior to intubation during administration of preoperative anesthesia. In the hemidiaphragm the larger voltage negative-positive potentials were rarely triggered by intracellular or tungsten microelectrodes. The negative-positive potentials, however, were clearly triggered by contact of the concentric needle electrode with muscle hemidiaphragm at the end-plate region. The potentials were abolished by curare. Likewise, the equivalent potentials observed at the human gastrocnemius end-plate zone were blocked by neuromuscular blocking agents. Therefore, these positive-negative discharges represent postsynaptic muscle fiber action potentials and not nerve fiber activity. They were probably presynaptically activated by mechanical irritation of the motor axon terminal and preterminal branches. PMID:6275771

  7. Phase contrast without phase plates and phase rings--optical solutions for improved imaging of phase structures.

    PubMed

    Piper, Timm; Piper, Jörg

    2013-10-01

    Using the optical methods described, phase specimens can be observed with a modified light microscope in enhanced clarity, purified from typical artifacts which are apparent in standard phase contrast illumination. In particular, haloing and shade-off are absent, lateral and vertical resolution are maximized and the image quality remains constant even in problematic preparations which cannot be well examined in normal phase contrast, such as specimens beyond a critical thickness or covered by obliquely situated cover slips. The background brightness and thus the range of contrast can be continuously modulated and specimens can be illuminated in concentric-peripheral, axial or paraxial light. Additional contrast effects can be achieved by spectral color separation. Normal glass or mirror lenses can be used; they do not need to be fitted with a phase plate or a phase ring. The methods described should be of general interest for all disciplines using phase microscopy. PMID:23913620

  8. Plate kinematics, slab shape and back-arc stress: A comparison between laboratory models and current subduction zones

    NASA Astrophysics Data System (ADS)

    Heuret, A.; Funiciello, F.; Faccenna, C.; Lallemand, S.

    2007-04-01

    A combination of statistical studies on present-day subduction zones and three-dimensional (3D) laboratory models is performed with the aim to clarify the way that plate kinematics control the geometry of the slab and the overriding plate deformation in subduction zones. In 3D laboratory models, the analogue of a two layer linearly viscous lithosphere-upper mantle system is achieved by means of silicon putty glucose syrup tank experiment. The subducting and overriding plate velocities are systematically changed by exploring the variability field of natural plate kinematics. Both statistical and modelling approaches recognize the importance of overriding plate motion on subduction process behavior: (1) trenches migrate at a rate close to the overriding plate motion, but always move slower than the overriding plates. The mechanism at work is a direct consequence of "slab anchoring" opposed by both lithosphere and mantle viscous resistance and is responsible for overriding plate deformation and slab geometry variability. (2) An overriding plate shortens when the overriding plate moves toward the trench and conditions that are favourable for overriding plate extension are created when the overriding plate moves away from the trench. (3) Shallow and steep dips are found if the overriding plate moves toward and away from the trench, respectively.

  9. Evidence of lower-mantle slab penetration phases in plate motions.

    PubMed

    Goes, Saskia; Capitanio, Fabio A; Morra, Gabriele

    2008-02-21

    It is well accepted that subduction of the cold lithosphere is a crucial component of the Earth's plate tectonic style of mantle convection. But whether and how subducting plates penetrate into the lower mantle is the subject of continuing debate, which has substantial implications for the chemical and thermal evolution of the mantle. Here we identify lower-mantle slab penetration events by comparing Cenozoic plate motions at the Earth's main subduction zones with motions predicted by fully dynamic models of the upper-mantle phase of subduction, driven solely by downgoing plate density. Whereas subduction of older, intrinsically denser, lithosphere occurs at rates consistent with the model, younger lithosphere (of ages less than about 60 Myr) often subducts up to two times faster, while trench motions are very low. We conclude that the most likely explanation is that older lithosphere, subducting under significant trench retreat, tends to lie down flat above the transition to the high-viscosity lower mantle, whereas younger lithosphere, which is less able to drive trench retreat and deforms more readily, buckles and thickens. Slab thickening enhances buoyancy (volume times density) and thereby Stokes sinking velocity, thus facilitating fast lower-mantle penetration. Such an interpretation is consistent with seismic images of the distribution of subducted material in upper and lower mantle. Thus we identify a direct expression of time-dependent flow between the upper and lower mantle. PMID:18288192

  10. Theoretical Investigation of Calculating Temperatures in the Combining Zone of Cu/Fe Composite Plate Jointed by Explosive Welding

    NASA Astrophysics Data System (ADS)

    Qu, Y. D.; Zhang, W. J.; Kong, X. Q.; Zhao, X.

    2016-03-01

    The heat-transfer behavior of the interface of Flyer plate (or Base Plate) has great influence on the microcosmic structures, stress distributions, and interface distortion of the welded interface of composite plates by explosive welding. In this paper, the temperature distributions in the combing zone are studied for the case of Cu/Fe composite plate jointed by explosive welding near the lower limit of explosive welding. The results show that Flyer plate (Cu plate) and Base Plate (Fe plate) firstly almost have the same melting rate in the explosive welding process. Then, the melting rate of Cu plate becomes higher than that of Fe plate. Finally, the melt thicknesses of Cu plate and Fe plate trend to be different constants, respectively. Meanwhile, the melting layer of Cu plate is thicker than that of Fe plate. The research could supply some theoretical foundations for calculating the temperature distribution and optimizing the explosive welding parameters of Cu/Fe composite plate to some extent.

  11. Upgrading multilayer zone plate technology for hard x-ray focusing

    NASA Astrophysics Data System (ADS)

    Hirotomo, Toshiki; Takano, Hidekazu; Sumida, Kazuhiro; Koyama, Takahisa; Konishi, Shigeki; Ichimaru, Satoshi; Ohchi, Tadayuki; Takenaka, Hisataka; Tsusaka, Yoshiyuki; Kagoshima, Yasushi

    2016-01-01

    Multilayer zone plate (MZP) technology for hard X-ray focusing was upgraded and its focusing performance was evaluated using 20-keV X-rays at the synchrotron beamline (BL24XU) of SPring-8. The MZP consists of MoSi2 and Si layers alternately deposited on a glass fiber by magnetron sputtering so that all zone boundaries satisfy the Fresnel zone configuration. The focused beam was evaluated using knife-edge scanning in which the measured intensity distribution is identical to the line spread function (LSF) in the focal plane. The focused beamsize of about 30 nm was estimated by oscillation peaks observed in the measured LSF according to Rayleigh's criterion.

  12. Exposed plate interface in the European Alps reveals fabric styles and gradients related to an ancient seismogenic coupling zone

    NASA Astrophysics Data System (ADS)

    Bachmann, Raik; Oncken, Onno; Glodny, Johannes; Seifert, Wolfgang; Georgieva, Viktoria; Sudo, Masafumi

    2009-05-01

    We present observations from a continuous exposure of an ancient plate interface in the depth range of its former seismogenic zone in the central Alps of Europe related to Late Cretaceous-early Tertiary subduction and accretion of the South Penninic lower plate underneath the Adriatic upper plate. The material forming the exposed plate interface zone has experienced flow and fracturing over an extended period of time followed by syncollisional exhumation, thus reflecting a multistage evolution. Fabric formation and metamorphism, however, chiefly record the deformation conditions of the precollisional setting along the plate interface. We identify an unstable slip domain from pseudotachylytes occurring in the temperature range between 200 and 300°C. This zone coincides with a domain of intense veining in the subduction mélange with mineral growth into open cavities, indicating fast, possibly seismic, rupture. Evidence for transient near-lithostatic fluid pressure as well as brittle fractures competing with mylonitic shear zones continues into the region below the occurrence of pseudotachylytes, possibly reflecting a zone of conditionally stable slip. The zone above the unstable slip area is devoid of veins but displays ample evidence of fluid-assisted processes similar to the deeper zone: solution-precipitation creep and dehydration reactions in the mélange matrix, hydration, and sealing of the base of the upper plate. Seismic rupture here is possibly expressed by ubiquitous localized deformation zones. We hypothesize that trenchward sealing of parts of the plate interface as well as reaction-enhanced destruction of upper plate permeability is an important component, localizing the unstable slip zone. This relation may result from the competition of the pervasive, presumably interseismic, pressure solution creep destroying permeability and building elevated fluid pressure until the strength threshold is reached with seismic failure.

  13. Soft X-Ray Microscopy at HZB: Zone Plate Development and Imaging Using the Third Order of Diffraction

    NASA Astrophysics Data System (ADS)

    Rehbein, S.; Guttmann, P.; Werner, S.; Schneider, G.

    2011-09-01

    The Helmholtz-Zentrum Berlin (HZB) operates a transmission x-ray microscope (TXM) in the soft x-ray photon energy range with an energy resolution up to E/ΔE = 104 [1]. An approach to achieve ultrahigh spatial resolution with conventional, standard zone plate optics is to employ higher orders of diffraction of the zone plate objective [2]. In this paper, we demonstrate that 11-nm lines and spaces of a multilayer test structure are clearly resolved by the x-ray microscope using the third order of diffraction of a zone plate objective with 20-nm outermost zone width. The disadvantage of high-order imaging is an about one order of magnitude lower diffraction efficiency of the used zone plates employed in the third order compared to the first order of diffraction. In addition, the measured background signal in the TXM images is no longer negligible. Therefore, we worked on the fabrication of zone plates with sub-20-nm outermost zone width to increase the spatial resolution in the first order of diffraction. A new high-resolution 100-keV e-beam lithography system from VISTEC, which was recently installed at the Helmholtz-Zentrum Berlin, makes these developments possible. Initial results on zone plates with an outermost zone width down to 15 nm exposed with the new e-beam system are presented. Furthermore, the contrast transfer function of the transmission x-ray microscope operating in partial coherence mode is measured by using the first and third diffraction order of the zone plate objective.

  14. Soft X-Ray Microscopy at HZB: Zone Plate Development and Imaging Using the Third Order of Diffraction

    SciTech Connect

    Rehbein, S.; Guttmann, P.; Werner, S.; Schneider, G.

    2011-09-09

    The Helmholtz-Zentrum Berlin (HZB) operates a transmission x-ray microscope (TXM) in the soft x-ray photon energy range with an energy resolution up to E/{Delta}E = 10{sup 4}. An approach to achieve ultrahigh spatial resolution with conventional, standard zone plate optics is to employ higher orders of diffraction of the zone plate objective. In this paper, we demonstrate that 11-nm lines and spaces of a multilayer test structure are clearly resolved by the x-ray microscope using the third order of diffraction of a zone plate objective with 20-nm outermost zone width. The disadvantage of high-order imaging is an about one order of magnitude lower diffraction efficiency of the used zone plates employed in the third order compared to the first order of diffraction. In addition, the measured background signal in the TXM images is no longer negligible. Therefore, we worked on the fabrication of zone plates with sub-20-nm outermost zone width to increase the spatial resolution in the first order of diffraction. A new high-resolution 100-keV e-beam lithography system from VISTEC, which was recently installed at the Helmholtz-Zentrum Berlin, makes these developments possible. Initial results on zone plates with an outermost zone width down to 15 nm exposed with the new e-beam system are presented. Furthermore, the contrast transfer function of the transmission x-ray microscope operating in partial coherence mode is measured by using the first and third diffraction order of the zone plate objective.

  15. Performance characterization of a broadband vector Apodizing Phase Plate coronagraph.

    PubMed

    Otten, Gilles P P L; Snik, Frans; Kenworthy, Matthew A; Miskiewicz, Matthew N; Escuti, Michael J

    2014-12-01

    One of the main challenges for the direct imaging of planets around nearby stars is the suppression of the diffracted halo from the primary star. Coronagraphs are angular filters that suppress this diffracted halo. The Apodizing Phase Plate coronagraph modifies the pupil-plane phase with an anti-symmetric pattern to suppress diffraction over a 180 degree region from 2 to 7 λ/D and achieves a mean raw contrast of 10(-4) in this area, independent of the tip-tilt stability of the system. Current APP coronagraphs implemented using classical phase techniques are limited in bandwidth and suppression region geometry (i.e. only on one side of the star). In this paper, we introduce the vector-APP (vAPP) whose phase pattern is implemented through the vector phase imposed by the orientation of patterned liquid crystals. Beam-splitting according to circular polarization states produces two, complementary PSFs with dark holes on either side. We have developed a prototype vAPP that consists of a stack of three twisting liquid crystal layers to yield a bandwidth of 500 to 900 nm. We characterize the properties of this device using reconstructions of the pupil-plane pattern, and of the ensuing PSF structures. By imaging the pupil between crossed and parallel polarizers we reconstruct the fast axis pattern, transmission, and retardance of the vAPP, and use this as input for a PSF model. This model includes aberrations of the laboratory set-up, and matches the measured PSF, which shows a raw contrast of 10(-3.8) between 2 and 7 λ/D in a 135 degree wedge. The vAPP coronagraph is relatively easy to manufacture and can be implemented together with a broadband quarter-wave plate and Wollaston prism in a pupil wheel in high-contrast imaging instruments. The liquid crystal patterning technique permits the application of extreme phase patterns with deeper contrasts inside the dark holes, and the multilayer liquid crystal achromatization technique enables unprecedented spectral bandwidths

  16. Modeling the Philippine Mobile Belt: Tectonic blocks in a deforming plate boundary zone

    NASA Astrophysics Data System (ADS)

    Galgana, G. A.; Hamburger, M. W.; McCaffrey, R.; Bacolcol, T. C.; Aurelio, M. A.

    2007-12-01

    The Philippine Mobile Belt, a seismically active, rapidly deforming plate boundary zone situated along the convergent Philippine Sea/Eurasian plate boundary, is examined using geodetic and seismological data. Oblique convergence between the Philippine Sea Plate and the Eurasian plate is accommodated by nearly orthogonal subduction along the Philippine Trench and the Manila Trench, as well as by strike-slip faulting along the Philippine Fault system. We develop a model of active plate boundary deformation in this region, using elastic block models constrained by known fault geometries, published GPS observations and focal mechanism solutions. We then present an estimate of block rotations, fault coupling, and intra-block deformation, based on the best-fit model that minimizes the misfit between observed and predicted geodetic vectors and earthquake slip vectors. Slip rates along the Philippine fault vary from ~22 - 36 mm/yr in the Central Visayas and about 10 to 40 mm/yr in Luzon, trending almost parallel to the fault trace. In northern Luzon, Philippine Fault splays accommodate transpressional strain. The Central Visayas block experiences convergence with the Sundaland block along the Negros Trench and the Mindoro-Palawan collision zone. On the eastern side of Central Visayas, sinistral strike-slip faulting occurs along the NNW-SSE-trending Philippine Fault. Mindanao Island in southern Philippines is dominated by east-verging subduction along the Cotabato Trench, and strain partitioning (strike- slip faulting with west-verging subduction) in eastern Mindanao along the southern Philippine Fault and Philippine Trench, respectively. Oblique active sinistral strike slip faults in Central and Eastern Mindanao that were hypothesized to be responsible for basin formation are obvious boundaries for tectonic blocks. Located south of Mindanao Island we define an adjoining oceanic block defined by the N-S trending complex dual subduction zone of Sangihe and Halmahera

  17. High-performance multilevel blazed x-ray microscopy Fresnel zone plates: Fabricated using x-ray lithography

    SciTech Connect

    Di Fabrizio, E.; Gentili, M.; Grella, L.; Baciocchi, M. , I-00156 Rome ); Krasnoperova, A.; Cerrina, F. ); Yun, W.; Lai, B.; Gluskin, E. )

    1994-11-01

    Diffractive lenses are becoming the optical elements of choice for many applications. One type of diffractive lens, the binary zone plate, has already demonstrated high-resolution performance experimentally. However, in order to increase the diffraction efficiency of these zone plates, a blazed grating profile must be used. This can best be approximated by a staircase grating profile, created by multilevel exposures. Using x-ray lithograph, we fabricated for the first time circular, linear bi- and trilevel zone plates, with gold structures 0.75 [mu]m thick (per level), on silicon nitride substrates. The zone plates were designed for use at a wavelength of 1.54 A, and had a theoretical efficiency of 68.5% for bilevel and 81.5% for trilevel zone plates. Due to the large depth of focus and high resolution inherent to x-ray lithography, the finished zone plate exhibits very steep sidewall profiles, with linewidth resolution down to 0.25 [mu]m. Such vertical sidewalls are essential for achieving high lens efficiency. Fabrication errors, such as thickness variation in the electroplated gold and misalignment, were considered, and their effect on the optical efficiency of the zone plate was estimated. Alignment errors between levels were minimized, achieving a best result of 25 nm (3[sigma]). In fabricating the zone plates, we employed standard integrated device tools, such as a Leica Cambridge Electron Beam microfabricator (EBMF) 10cs/120 electron-beam writer for the x-ray mask fabrication, and a Suss 200 x-ray stepper for the multilevel exposures. Thus, we have shown that it will be possible to fabricate many lenses, with a variety of optical characteristics, in one wafer.

  18. Magnetic Barkhausen noise for reliable detection of the heat affected zone in welded ship steel plate

    NASA Astrophysics Data System (ADS)

    Blaow, Mohamed M.; Shaw, Brian A.

    2014-02-01

    The applicability of the Barkhausen noise technique to non-destructively determine the heat affected zone (HAZ) in welded steel plates was investigated. Magnetic Barkhausen noise measurements were conducted on welded hot-rolled low carbon ship steel plates to determine the MBN behaviour following the exposure to elevated heat in a localized region by welding. The exciting field was applied parallel to the weld bead. The results showed a variation in MBN level along a line that crosses the weld bead. The MBN intensity was higher in the near weld material compared with a lower intensity when the measurement setup was moved away from the weld bead in both sides of the weld. The increased MBN level was attributed to the induced residual tensile stresses as a result of the shrinkage of the hot zone. The variation of MBN along the measurement line was eliminated after the welded plate was shot peened. The decrease in MBN intensity after shot peening was attributed to the induced compressive stresses. The results were explained in terms of different mechanisms of interaction of domain walls with residual tensile and compressive stresses.

  19. High-efficiency multilevel zone plates for keV X-rays

    NASA Astrophysics Data System (ADS)

    di Fabrizio, E.; Romanato, F.; Gentili, M.; Cabrini, S.; Kaulich, B.; Susini, J.; Barrett, R.

    1999-10-01

    The development of high brilliance X-ray sources coupled with advances in manufacturing technologies has led to significant improvements in submicrometre probes for spectroscopy, diffraction and imaging applications. The generation of a small beam spot size is commonly based on three principles: total reflection (as used in optical elements involving mirrors or capillaries), refraction (such as in refractive lenses) and diffraction. The latter effect is employed in Bragg-Fresnel or Soret lenses, commonly known as Fresnel zone plate lenses. These lenses currently give the best spatial resolution, but are traditionally limited to rather soft X-rays-at high energies, their use is still limited by their efficiency. Here we report the fabrication of high-efficiency, high-contrast gold and nickel multistep (quaternary) Fresnel zone plates using electron beam lithography. We achieve a maximum efficiency of 55% for the nickel plate at 7keV. In addition to their high efficiency, the lenses offer the advantages of low background signal and effective reduction of unwanted diffraction orders. We anticipate that these lenses should have a significant impact on techniques such as microscopy, micro-fluorescence and micro-diffraction, which require medium resolution (500-100nm) and high flux at fixed energies.

  20. Lost in Iceland? Fracture Zone Complications Along the Mid-Atlantic Plate Boundary

    NASA Astrophysics Data System (ADS)

    Brandsdóttir, B.; Einarsson, P.; Detrick, R. S.; Mayer, L.; Calder, B.; Driscoll, N.; Richter, B.

    2003-12-01

    The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. Two transform zones, the South Iceland Seismic Zone (SISZ) and the Tjörnes Fracture Zone (TFZ) separate the on land rift zones from the Reykjanes Ridge (RR), and the Kolbeinsey Ridge (KR), offshore N-Iceland. Both are markedly different from fracture zones elsewhere along the plate boundary. The 80 km E-W and 10--15 km N-S SISZ is made up of more than 20 N-S aligned, right-lateral, strike-slip faults whereas the TFZ consists of a broad zone of deformation, roughly 150 km E-W and 75 km N-S. The over-all left-lateral transform motion within the SISZ is accommodated by bookshelf faulting whereas the right-lateral transform motion within the TFZ is incorporated within two WNW-trending seismic zones, spaced ˜40 km apart, the Grímsey Seismic Zone (GSZ) and the Húsavík-Flatey fault (HFF). Recently collected EM300 and RESON8101 multibeam bathymetric data along with CHIRP subbottom data has unveiled some tectonic details within the TFZ. The GSZ runs along the offshore extension of the Northern Volcanic Rift Zone (NVRZ) and is made up of four left-stepping, en-echelon, NS-striking rift segments akin to those on land. Large GSZ earthquakes seem to be associated with lateral strike-slip faulting along ESE-striking fault planes. Fissure swarms transecting the offshore volcanic systems have also been subjected to right-lateral transformation along the spreading direction. As the Reykjanes Peninsula, the on land extension of the RR, the GSZ bears the characteristics of an oblique rift zone. The plate boundary segments connecting to the RR and KR are thus symmetrical with respect to the plate separation vector (105° ) and orientation of individual volcanic systems. The HFF has an overall strike of N65° W and can be traced continuously along its 75--80 km length, between the Theistareykir volcanic system within the NVRZ, across the central TFZ-graben, the Skjálfandi bay, and into the largest

  1. Upper boundary of the Pacific plate subducting beneath Hokkaido, Japan, estimated from ScSp phase

    NASA Astrophysics Data System (ADS)

    Osada, Kinue; Yoshizawa, Kazunori; Yomogida, Kiyoshi; Suetsugu, Daisuke; Bina, Craig; Inoue, Toru; Wiens, Douglas; Jellinek, Mark

    2010-11-01

    Three-dimensional geometry of the upper boundary of the Pacific plate subducting beneath Hokkaido, Japan, was obtained using the ScSp phase: the phase converted from ScS (S wave reflected at the core•mantle boundary) to P wave at the plate boundary. Taking the advantage of a dense seismic network, "Hi-net", recently deployed across the Japanese islands, we applied several seismic array analyses to the recorded waveform data for a large nearby deep earthquake, in order to enhance very weak ScSp signals in the original records. At first, we set up five blocks for the region in plate dip directions. After aligning the travel times of ScS and stacking seismograms among stations in a given sub-block perpendicular to each dip direction, we searched for the optimal plate model (i.e., two-dimensional geometry of the upper boundary) for each block. The model was parameterized by seven depth grids, and seismograms were stacked based on the travel time of ScSp as a time lag of each sub-block, so that the optimal model would yield the maximum spectral energy of ScSp after stacking. This model parameter search was conducted, using ray tracings of ScSp with a reference velocity model and a non-linear inversion scheme (Neighbourhood Algorithm). The optimal model of each block was combined each other by cubic spline interpolation, in order to construct an overall three-dimensional geometry of the upper boundary of the plate. Next, we performed the frequency•wavenumber (f•k) spectral analysis to refine the above result. Assuming each station as a reference point, we made beam output from records of its adjacent stations as a function of wavenumber vector (kx,ky) and frequency. The peak of its power spectrum was considered to represent the wavenumber vector of ScSp, that is, azimuth of arrival and slowness, so that we can estimate the position and depth of the corresponding ScS•ScSp conversion. In the frequency range from 0.5 to 1.5 Hz, we could estimate the conversion

  2. Spectrum of slip behaviour in Tohoku fault zone samples at plate tectonic slip rates

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.; Ito, Yoshihiro; Ujiie, Kohtaro; Kopf, Achim J.

    2015-11-01

    During the 2011 Tohoku-oki earthquake, extremely extensive coseismic slip ruptured shallow parts of the Japan Trench subduction zone and breached the sea floor. This part of the subduction zone also hosts slow slip events (SSE). The fault thus seems to have a propensity for slip instability or quasi-instability that is unexpected on the shallow portions of important fault zones. Here we use laboratory experiments to slowly shear samples of rock recovered from the Tohoku-oki earthquake fault zone as part of the Japan Trench Fast Drilling Project. We find that infrequent perturbations in rock strength appear spontaneously as long-term SSE when the samples are sheared at a constant rate of about 8.5 cm yr-1, equivalent to the plate-convergence rate. The shear strength of the rock drops by 3 to 6%, or 50 kPa to 120 kPa, over about 2 to 4 h. Slip during these events reaches peak velocities of up to 25 cm yr-1, similar to SSE observed in several circum-Pacific subduction zones. Furthermore, the sheared samples exhibit the full spectrum of fault-slip behaviours, from fast unstable slip to slow steady creep, which can explain the wide range of slip styles observed in the Japan Trench. We suggest that the occurrence of SSE at shallow depths may help identify fault segments that are frictionally unstable and susceptible to large coseismic slip propagation.

  3. Pore pressure evolution at the plate interface along the Cascadia subduction zone from the trench to the ETS transition zone

    NASA Astrophysics Data System (ADS)

    Skarbek, R. M.; Rempel, A. W.; Schmidt, D. A.

    2010-12-01

    Pore fluid pressures in subduction zones are a primary control on fault strength and slip dynamics. Numerous studies document elevated pore pressures in the outer wedge along several margins. Seismic observations and the occurrence of non-volcanic tremor provide additional evidence for the presence of near-lithostatic pore pressures at the plate interface far down-dip from the trench (~35 km depth). Here we use numerical models in one and two dimensions to evaluate the pore pressure and compaction state of sediments on the subducting Juan de Fuca plate in Cascadia from the trench to the ETS zone. 2-D models allow pressure to diffuse vertically and also laterally normal to strike of the megathrust; 1-D models simulate only vertical diffusion. Model parameters are chosen with reference to two strike-normal profiles: one through central Oregon and one through the Olympic Peninsula of Washington. We examine temporal variations in sediment input to the trench and consider implications for fault strength and permeability as well as the down-dip extent to which compactive dewatering can be considered a significant fluid source. In 1-D, we use a general and fully nonlinear model of sediment compaction derived without making any assumptions regarding stress-strain or porosity-permeability relations and allowing finite strains. In contrast, most previous models of fluid flow in subduction zones have used linear models of diffusion that rely on assumptions of constant sediment permeability and infinitesimal strains for their formulation. Our nonlinear finite-strain model remains valid at greater depths, where stresses and strains are large. Boundary conditions in 1-D are constrained by pore pressure estimates along the megathrust fault that are based on seismic velocities (e.g. Tobin and Saffer, 2010) and data from consolidation tests conducted on sediments gathered during ODP Leg 204 (Tan, 2001). Initial conditions rely on input sediment thickness; while sediment thickness

  4. Seismic evidence for fluids in fault zones on top of the subducting Cocos Plate beneath Costa Rica

    NASA Astrophysics Data System (ADS)

    Van Avendonk, Harm J. A.; Holbrook, W. Steven; Lizarralde, Daniel; Mora, Mauricio M.; Harder, Steven; Bullock, Andrew D.; Alvarado, Guillermo E.; Ramírez, Carlos J.

    2010-05-01

    In the 2005 TICOCAVA explosion seismology study in Costa Rica, we observed crustal turning waves with a dominant frequency of ~10 Hz on a linear array of short-period seismometers from the Pacific Ocean to the Caribbean Sea. On one of the shot records, from Shot 21 in the backarc of the Cordillera Central, we also observed two seismic phases with an unusually high dominant frequency (~20 Hz). These two phases were recorded in the forearc region of central Costa Rica and arrived ~7 s apart and 30-40 s after the detonation of Shot 21. We considered the possibility that these secondary arrivals were produced by a local earthquake that may have happened during the active-source seismic experiment. Such high-frequency phases following Shot 21 were not recorded after Shots 22, 23 and 24, all in the backarc of Costa Rica, which might suggest that they were produced by some other source. However, earthquake dislocation models cannot produce seismic waves of such high frequency with significant amplitude. In addition, we would have expected to see more arrivals from such an earthquake on other seismic stations in central Costa Rica. We therefore investigate whether the high-frequency arrivals may be the result of a deep seismic reflection from the subducting Cocos Plate. The timing of these phases is consistent with a shear wave from Shot 21 that was reflected as a compressional (S×P) and a shear (S×S) wave at the top of the subducting Cocos slab between 35 and 55 km depth. The shift in dominant frequency from ~10 Hz in the downgoing seismic wave to ~20 Hz in the reflected waves requires a particular seismic structure at the interface between the subducting slab and the forearc mantle to produce a substantial increase in reflection coefficients with frequency. The spectral amplitude characteristics of the S×P and S×S phases from Shot 21 are consistent with a very high Vp/Vs ratio of 6 in ~5 m thick, slab-parallel layers. This result suggests that a system of thin shear

  5. Design of an advanced two-phase capillary cold plate

    NASA Technical Reports Server (NTRS)

    Chalmers, D. R.; Kroliczek, E. J.; Ku, J.

    1986-01-01

    The functional principles and implementation of capillary pumped loop (CPL) two phase heat transport system for various elements of the Space Station program are described. Circulation of the working fluid by the surface-tension forces in a fine-pore capillary wick is the core principle of CPL systems. The liquid, usually NH3 at the moment, is changed into a vapor by heat absorption at one end of the loop, and the vapor is carrried back along the wick by the surface tension within the wick. NASA specifications and the results of mechanical and thermal tests for prototype cold plate and the capillary pump designs are outlined. The CPL is targeted for installation on free-flying platforms, attached payloads, and power subsystem thermal control systems.

  6. Production of distributed phase plates using an energetic ion process

    NASA Astrophysics Data System (ADS)

    Smith, Douglas J.; Warner, Joy A.; LeBarron, Nelson E.; LaDelia, Salvatore

    1999-04-01

    Laser-driven implosion experiments require optical phase conversion to create a uniformly irradiated target. Distributed phase plates provide a quasi-random phase front that aids in beam smoothing on the target; however, the DPP must survive the high fluences of the tripled OMEGA beam at 351 nm. The continuous DPP produces higher efficiency and less risk of damage to opposing optics than the previous binary design. DPPs are created by exposing a gray scale pattern in photoresist and then etching the pattern in to silica. Several problems were solved during the development stage of ion etching DPPs. The etch uniformity was limited to less than 6 percent across a 28-cm clear aperture by modeling the 16-cm ion source and erosion characteristics of the photoresist and silica. Surface texturing was linked to overheating of the photoresist by the ion source and was solved by radiant cooling. Near-field defects capable of focusing damage in levels of fluence on downstream optics were created in the photoresist exposure process and were removed after etching. The damage thresholds of the silica surface generally increase after etching is fare is taken to avoid re-sputtering of tooling onto the optics surface. Sixty ion-etched DPPs were installed in December 1997 and, currently, damage has not been observed on the optics.

  7. Electron cryotomography of vitrified cells with a Volta phase plate.

    PubMed

    Fukuda, Yoshiyuki; Laugks, Ulrike; Lučić, Vladan; Baumeister, Wolfgang; Danev, Radostin

    2015-05-01

    Electron cryotomography provides a means of studying the three dimensional structure of pleomorphic objects, such as organelles or cells, with a resolution of 1-3nm. A limitation in the study of radiation sensitive biological samples is the low signal-to-noise ratio of the tomograms which may obscure fine details. To overcome this limitation, the recently developed Volta phase plate (VPP) was applied in electron cryotomographic studies of a wide range of cellular structures, from magnetotactic bacteria to primary cultured neurons. The results show that the VPP improves contrast significantly and consequently the signal-to-noise ratio of the tomograms, moreover it avoids disturbing fringing artifacts typical for Zernike phase plates. The contrast improvement provided by the VPP was also confirmed in projection images of relatively thick (∼400nm) samples. In order to investigate the respective contributions of the VPP and the energy filter, images acquired with different combinations of the two were compared. Zero-loss energy filtering reduced the background noise in thicker areas of the sample and improved the contrast of features such as poly-β-hydroxybutyrate granules in magnetotactic bacteria, whereas the VPP provided an overall contrast improvement for all sample areas. After 3D reconstruction, tomograms acquired with the combination of a VPP and an energy filter showed structural features in neuronal processes with outstanding clarity. We also show that the VPP can be combined with focused ion beam milling to examine structures embedded deeply inside cells. Thus, we expect that VPP will become a standard element of the electron cryotomography workflow. PMID:25770733

  8. Water, oceanic fracture zones and the lubrication of subducting plate boundaries—insights from seismicity

    NASA Astrophysics Data System (ADS)

    Schlaphorst, David; Kendall, J.-Michael; Collier, Jenny S.; Verdon, James P.; Blundy, Jon; Baptie, Brian; Latchman, Joan L.; Massin, Frederic; Bouin, Marie-Paule

    2016-03-01

    We investigate the relationship between subduction processes and related seismicity for the Lesser Antilles Arc using the Gutenberg-Richter law. This power law describes the earthquake-magnitude distribution, with the gradient of the cumulative magnitude distribution being commonly known as the b-value. The Lesser Antilles Arc was chosen because of its along-strike variability in sediment subduction and the transition from subduction to strike-slip movement towards its northern and southern ends. The data are derived from the seismicity catalogues from the Seismic Research Centre of The University of the West Indies and the Observatoires Volcanologiques et Sismologiques of the Institut de Physique du Globe de Paris and consist of subcrustal events primarily from the slab interface. The b-value is found using a Kolmogorov-Smirnov test for a maximum-likelihood straight line-fitting routine. We investigate spatial variations in b-values using a grid-search with circular cells as well as an along-arc projection. Tests with different algorithms and the two independent earthquake cataloges provide confidence in the robustness of our results. We observe a strong spatial variability of the b-value that cannot be explained by the uncertainties. Rather than obtaining a simple north-south b-value distribution suggestive of the dominant control on earthquake triggering being water released from the sedimentary cover on the incoming American Plates, or a b-value distribution that correlates with on the obliquity of subduction, we obtain a series of discrete, high b-value `bull's-eyes' along strike. These bull's-eyes, which indicate stress release through a higher fraction of small earthquakes, coincide with the locations of known incoming oceanic fracture zones on the American Plates. We interpret the results in terms of water being delivered to the Lesser Antilles subduction zone in the vicinity of fracture zones providing lubrication and thus changing the character of the

  9. Rheological structure of the lithosphere in plate boundary strike-slip fault zones

    NASA Astrophysics Data System (ADS)

    Chatzaras, Vasileios; Tikoff, Basil; Kruckenberg, Seth C.; Newman, Julie; Titus, Sarah J.; Withers, Anthony C.; Drury, Martyn R.

    2016-04-01

    How well constrained is the rheological structure of the lithosphere in plate boundary strike-slip fault systems? Further, how do lithospheric layers, with rheologically distinct behaviors, interact within the strike-slip fault zones? To address these questions, we present rheological observations from the mantle sections of two lithospheric-scale, strike-slip fault zones. Xenoliths from ˜40 km depth (970-1100 ° C) beneath the San Andreas fault system (SAF) provide critical constraints on the mechanical stratification of the lithosphere in this continental transform fault. Samples from the Bogota Peninsula shear zone (BPSZ, New Caledonia), which is an exhumed oceanic transform fault, provide insights on lateral variations in mantle strength and viscosity across the fault zone at a depth corresponding to deformation temperatures of ˜900 ° C. Olivine recrystallized grain size piezometry suggests that the shear stress in the SAF upper mantle is 5-9 MPa and in the BPSZ is 4-10 MPa. Thus, the mantle strength in both fault zones is comparable to the crustal strength (˜10 MPa) of seismogenic strike-slip faults in the SAF system. Across the BPSZ, shear stress increases from 4 MPa in the surrounding rocks to 10 MPa in the mylonites, which comprise the core of the shear zone. Further, the BPSZ is characterized by at least one order of magnitude difference in the viscosity between the mylonites (1018 Paṡs) and the surrounding rocks (1019 Paṡs). Mantle viscosity in both the BPSZ mylonites and the SAF (7.0ṡ1018-3.1ṡ1020 Paṡs) is relatively low. To explain our observations from these two strike-slip fault zones, we propose the "lithospheric feedback" model in which the upper crust and lithospheric mantle act together as an integrated system. Mantle flow controls displacement and the upper crust controls the stress magnitude in the system. Our stress data combined with data that are now available for the middle and lower crustal sections of other transcurrent fault

  10. Retrofit implementation of Zernike phase plate imaging for cryo-TEM

    PubMed Central

    Marko, Michael; Leith, ArDean; Hsieh, Chyongere; Danev, Radostin

    2011-01-01

    In-focus phase-plate imaging is particularly beneficial for cryo-TEM because it offers a substantial overall increase in image contrast, without an electron dose penalty, and it simplifies image interpretation. We show how phase-plate cryo-TEM can be implemented with an appropriate existing TEM, and provide a basic practical introduction to use of thin-film (carbon) phase plates. We point out potential pitfalls of phase-plate operation, and discuss solutions. We provide information on evaluating a particular TEM for its suitability. PMID:21272647

  11. Effects of low-spatial-frequency response of phase plates on TEM imaging

    NASA Astrophysics Data System (ADS)

    Edgcombe, C. J.

    2015-10-01

    Images of simple objects produced by a perfect lens and a phase plate have been calculated by use of Abbe theory for Foucault, Hilbert and Zernike phase plates. The results show that with a Zernike plate, white outlines and ringing like those observed previously can be caused by the beam hole, which limits the low-spatial-frequency response of the system even when the lens behaves perfectly. When the change of phase added by the phase plate is distributed over a range of radius rather than a simple step, the unwanted effects are substantially reduced.

  12. Analysis of Stress Field in Caribean Continental Plate - Southern Costa Rica zone - from CMT Solutions

    NASA Astrophysics Data System (ADS)

    Zevallos, I.; Quintero, R.; Jimenez, W.

    2007-12-01

    During the of period 1984 2007, 51 earthquakes were registered with magnitudes above 5.1 mb in southern Costa Rica. Depth distribution of hypocenters shows shallow (0 20 km) earthquakes located in continental area; intermediate depth hypocenters (20 60 km) corresponding to subduction of the Coco plate under the Caribean plate; and just one earthquake have focus under 60 km depth. We choose hypocenters shallower than 100 km because our goal is to study intraplate stresses. Centroid Moment Tensor solutions for subduction zone earthquakes have inverse fault mechanism. But, in continental area there are evidences of strike slip and normal fault mechanisms. Direction of main stress (σ3) at the southern continental zone is NE-SW; in the Pacific ocean border region, the main stresses are oriented parallel to the coast line; inside the valley region, mechanisms are predominantly strike slip with σ1 in the near N-S direction. This is a complex stress field, with rotation of main stresses in a short space. σ1 is vertical in some continental areas due to influence of elevated terrain. Stress axis paralell to coast line maybe also due to gravitational body force.

  13. Role of the eastern California shear zone in accommodating Pacific-North American plate motion

    SciTech Connect

    Dokka, R.K.; Travis, C.J. )

    1990-08-01

    The newly recognized Eastern California shear zone (ECSZ) of the Mojave Desert-Death Valley region has played a major, but previously underappreciated role in accommodating the dextral shear between the Pacific and North American plates in late Cenozoic time. Comparison of integrated net slip along the shear zone with motion values across the entire transform boundary indicates that between 9% and 23% of the total relative plate motion has occurred along the ECSZ since its probably inception {approximately}10-6 Ma. Long-term integrated shear along the ECSZ (6-12 mm yr{sup {minus}1}) is similar to historic measurements (6.7 {plus minus} 1.3 mm yr{sup {minus}1}). Time-space patterns of faulting suggest that shear was concentrated in the eastern part of the Mojave Desert block and Death Valley during late Miocene and early Pleistocene time, but that the locus of faulting in the south-central Mojave jumped westward between 1.5 and 0.7 Ma.

  14. Dynamic Linkages Between the Transition Zone & Surface Plate Motions in 2D Models of Subduction

    NASA Astrophysics Data System (ADS)

    Arredondo, K.; Billen, M. I.

    2012-12-01

    Descending subducted slabs affect both plate tectonics at the surface and overall mantle flow (e.g. Conrad and Lithgow-Bertelloni, 2002). For time-dependent numerical models, the potential evolution of these slabs, ranging from immediate penetration into the lower mantle to prior buckling and stagnation, are affected by parameters such as the plate age, the viscosity jump into the lower mantle, the presence of phase transitions, trench motion and the chosen governing equation approximation (e.g. Billen and Hirth, 2007). Similarly, the overall deviatoric stress within the slab, especially where modified by the phase transitions, may explain the uneven distribution of deep earthquakes with depth (e.g. Bina, 1997). Better understanding of these processes may arise from a more realistic 2-D model that is fully-dynamic, with an overriding plate, freely-moving trench, compositionally-layered slab and seven major phase transitions, in addition to using the compressible (TALA) form of the governing equations. Though the thermodynamic parameters of certain phase transitions may be uncertain, this study aims to test the latest data and encourage further mineralogical research. We will present fully-dynamic models, which explore the importance of the phase transitions, especially those that have been previously excluded such as the wadsleyite to ringwoodite and the pyroxene and garnet phase transitions. These phase transitions, coupled with the modeled compositionally distinct crust, harzburgite, and pyrolite lithosphere layers, may produce new large-scale dynamic behavior not seen in past numerical models, as well as stress variations within the slab related to deep slab seismicity. Feedback from the compositionally complex slab to the dynamic trench may provide further insight on the mechanics of slab stagnation and behavior in the upper and lower mantle. Billen, M. I., and G. Hirth, Rheologic controls on slab dynamics, Geochemistry, Geophysics and Geosystems, 8 (Q08012

  15. Seismofocal zones and mid-ocean ridges - look outside of the plate paradigm

    NASA Astrophysics Data System (ADS)

    Anokhin, Vladimir; Kholmianskii, Mikhail

    2014-05-01

    Seismofocal zones and mid-ocean ridges - look outside of the plate paradigm Vladimir M. Anokhin, Mikhail A. Kholmianskii Configuration of the seismofocal zones (SFZ), visible in a real position of the focuses of earthquakes, has a significant step component (jagged) expressed by the presence of several sub-horizontal "seismoplanes", which concentrates focuses of earthquakes (depths 10, 35 km and other). Orientation of seismolines inside of SFZ tends to 4 main directions: 0-5 dgr, 120-145 dgr, 40-55 dgr, 85-90 dgr. These facts suggest significantly block, a terraced structure of the body of Benioff zone. The borders of blocks have orientation according directions regmatic net of the Earth. In accordance with this, SFZ can be presented as the most active segments of the border of the crossing: «continent-ocean», having the following properties: - block (terraced) structure; - in some sites - dive under the continental crust (in present time); - prevailing compression (in present time), perhaps, as the period of the oscillatory cycle; Infinite "subduction" in SFZ is unlikely. One of the areas where there is proof of concept of far "spreading" is the southernmost tip of the mid-oceanic Gakkel ridge in the Laptev sea (Arctic ocean). Here active "spreading" ridge normal approaches to the boundary of the continental crust - the shelf of the Laptev sea. On the shelf there are a number of subparallel NW grabens. NE fault zone Charlie, controlling the continental slope is established stepped fault without shift component. This means that the amount of extending of the offshore grabens does not significantly differ from the scale of spreading in the Gakkel ridge. However, the total spreads grabens (50-100 km) 6-10 times less than the width of the oceanic crust (600 km) in the surrounding area. Conclusion: the oceanic crust in the Laptev sea was formed mainly not due to "spreading". It is very likely that here was sinking and the processing of continental crust in the ocean

  16. A mega shear zone in the Central Range of Taiwan and it's implication for the Late Mesozoic subduction of the paleo-Pacific plate

    NASA Astrophysics Data System (ADS)

    Yi, D. C.; Lin, C. W.

    2012-04-01

    The metamorphic basement "Tananao Complex" exposed in the eastern flank of the Central Range of Taiwan. The ancient Asian continental margin deposited a thick sequence of sandstone, shale, limestone and volcanic rocks that was the protolith of Tananao Complex. In Late Mesozoic Era, the thick sequence of rocks was subjected to several phases of metamorphism and deformation to form the pair metamorphic belts which were the western Tailuko Belt and the eastern Yuli Belt. The Tailuko belt is composed of phyllite, quartzite, quartz-mica schist, meta-conglomerate, gneiss, meta-basite, amphibolite, serpentinite, marble and meta-chert, etc. The Yuli belt is composed of a monotonous assemblage of quartz-mica schist, subordinate meta-basite and serpentinite, etc. It is believed that the boundary of the Tailuko belt and the Yuli belt is a large fault, but the field evidence of the fault has never been found. In this study, meso-scale field investigation of the lithologies and rock fabrics indicate that a mega shear zone, called "The Daguan shear zone", separated the Tailuko belt from the Yuli belt. The Daguan shear zone is a NNE trending and west dipping mega shear zone which is mainly composed of mylonitic dark gray quartz-mica schist and mica schist, intercalated with 1 to 2 centimeters thick of elongated meta-conglomerate band. The shear zone is composed of numerous meso-scale ductile shear zones. Additionally, the shaer zone is characterized by abundant varied quartz veins that have been refolded to lenticular or pod shape and nearly parallel to S2 cleavage. Compaed to the existing geological information of the Central Range, we believe that the Daguan shear zone played a role as the boundary of the subduction zone which the paleo-Pacific Plate subducted into the Eurasian Plate in Late Mesozoic Era.

  17. Generation of adakites in a cold subduction zone due to double subducting plates

    NASA Astrophysics Data System (ADS)

    Nakamura, H.; Iwamori, H.

    2012-12-01

    Adakites have been found in various tectonic settings, since the first report for the distinct lavas as a product of slab melting in Adak Island by Kay (1978). In this study, we present geochemical data for an 'adakite' and 'adakitic rock' suite in central Japan with a cold subduction environment due to the two overlapping subudcting plates, the Pacific Plate and the Philippine Sea Plate. Based on the major, trace and isotopic compositions of the rocks, elemental transport from initial slab inventory at the trench to the volcanic rocks as a final product is quantitatively analyzed, considering the thermal structure, slab dehydration, elemental mobility, slab-fluid migration and melting of fluid-added mantle. The analysis demonstrates a large compositional impact of slab-fluid in the arc magma generation in central Japan. The melting conditions have been also estimated inversely by optimizing the predicted magma composition to the observed composition of volcanic rock, with the two parameters: the degree of melting and the proportion of spinel- and garnet-lherzolites involved in melting. Consequently, a low degree of melting of dominantly garnet-lherzolite with a high fluid flux from the two overlapping slabs beneath the region has been argued to be responsible for the compositional characteristics, including the adakitic signatures, of the studied rocks. These results imply that the geochemical approach may provide useful constraints on the P-T condition of melting in the mantle wedge and the thermal structure in subduction zones, being complementary to the geophysical approach. We have also applied this geochemical approach to the adjacent NE Japan where the Pacific plate subducts, which revealed the thermal regime in the mantle beneath the arc-arc transition.

  18. Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate boundary zone

    USGS Publications Warehouse

    van der Lelij, Roelant; Spikings, Richard A.; Kerr, Andrew C.; Kounov, Alexandre; Cosca, Michael; Chew, David; Villagomez, Diego

    2010-01-01

    Tectonic reconstructions of the Caribbean Plate are severely hampered by a paucity of geochronologic and exhumation constraints from anastomosed basement blocks along its southern margin. New U/Pb, 40Ar/39Ar, apatite fission track, and apatite (U-Th)/He data constrain quantitative thermal and exhumation histories, which have been used to propose a model for the tectonic evolution of the emergent parts of the Bonaire Block and the southern Caribbean Plate boundary zone. An east facing arc system intruded through an oceanic plateau during ~90 to ~87 Ma and crops out on Aruba. Subsequent structural displacements resulted in >80°C of cooling on Aruba during 70–60 Ma. In contrast, exhumation of the island arc sequence exposed on Bonaire occurred at 85–80 Ma and 55–45 Ma. Santonian exhumation on Bonaire occurred immediately subsequent to burial metamorphism and may have been driven by the collision of a west facing island arc with the Caribbean Plate. Island arc rocks intruded oceanic plateau rocks on Gran Roque at ~65 Ma and exhumed rapidly at 55–45 Ma. We attribute Maastrichtian-Danian exhumation on Aruba and early Eocene exhumation on Bonaire and Gran Roque to sequential diachronous accretion of their basement units to the South American Plate. Widespread unconformities indicate late Eocene subaerial exposure. Late Oligocene–early Miocene dextral transtension within the Bonaire Block drove subsidence and burial of crystalline basement rocks of the Leeward Antilles to ≤1 km. Late Miocene–recent transpression caused inversion and ≤1 km of exhumation, possibly as a result of the northward escape of the Maracaibo Block.

  19. Distribution and quantification of pyridinium cross-links of collagen within the different maturational zones of the chick growth plate.

    PubMed

    Farquharson, C; Duncan, A; Seawright, E; Whitehead, C C; Robins, S P

    1996-08-13

    In order to assess alterations in the collagen network during endochondral ossification the pyridinium cross-links of collagen were quantified in sequential transverse sections through the chick growth plate. This was accomplished using both morphological (alkaline phosphatase (ALP) histochemistry and collagen type X immunostaining) and analytical (HPLC) analyses. In articular cartilage, pyridinoline concentrations were maximal in the deep mature zones. In contrast, the proliferating chondrocyte zone of the growth plate had approximately a 10-fold greater pyridinoline cross-link concentration than the mature hypertrophic zone. Deoxypyridinoline was first found in the prehypertrophic zone of the growth plate cartilage that reacted positively for ALP activity but before collagen type X was detected. However, deoxypyridinoline concentrations were highest in the most differentiated regions of the growth plate where it was the principal pyridinium cross-link. In tibial dyschondroplasia, where chondrocyte differentiation is arrested in the prehypertrophic zone, higher concentrations of both cross-links were found with increasing distance down the lesion. We conclude that the decrease in pyridinoline cross-link concentration down the growth plate may be an essential adaptation (via increased collagenase activity and collagen turnover) of the matrix for vascular invasion and osteoclastic resorption to occur. PMID:8765127

  20. High-frequency Pn,Sn phases recorded by ocean bottom seismometers on the Cocos plate

    SciTech Connect

    McCreery, C.S.

    1981-05-01

    Data from ocean bottom seismometers located on the Cocos plate indicate that high-frequency Pn,Sn phases are generated by earthquakes along the subducting margin of that plate and are propagated across the plate. The Sn phase appears to be severely attenuated as it approaches the ridge crest. Estimates of Pn velocity are lower than previous extimates for western Pacific paths, which may indicate a relationship between Pn,Sn velocity and lithospheric age. High frequencies found in these phases suggest that Q for Pn,Sn propagation across the Cocos plate is similar to that for the western Pacific.

  1. Generation of plate tectonics with two-phase grain-damage and pinning: Source-sink model and toroidal flow

    NASA Astrophysics Data System (ADS)

    Bercovici, David; Ricard, Yanick

    2013-03-01

    The grain-damage and pinning mechanism of Bercovici and Ricard (2012) for lithospheric shear-localization is employed in two-dimensional flow calculations to test its ability to generate toroidal (strike-slip) motion and influence plate evolution. This mechanism posits that damage to the interface between phases in a polycrystalline material like peridotite (composed primarily of olivine and pyroxene) increases the number of small Zener pinning surfaces, which then constrain mineral grains to ever smaller sizes, regardless of creep mechanism. This effect allows a self-softening feedback in which damage and grain-reduction can co-exist with a grain-size dependent diffusion creep rheology; moreover, grain growth and weak-zone healing are greatly impeded by Zener pinning thereby leading to long-lived relic weak zones. The fluid dynamical calculations employ source-sink driven flow as a proxy for convective poloidal flow (upwelling/downwelling and divergent/convergent motion), and the coupling of this flow with non-linear rheological mechanisms excites toroidal or strike-slip motion. The numerical experiments show that pure dislocation-creep rheology, and grain-damage without Zener pinning (as occurs in a single-phase assemblages) permit only weak localization and toroidal flow; however, the full grain-damage with pinning readily allows focussed localization and intense, plate-like toroidal motion and strike-slip deformation. Rapid plate motion changes are also tested with abrupt rotations of the source-sink field after a plate-like configuration is developed; the post-rotation flow and material property fields retain memory of the original configuration for extensive periods, leading to suboptimally aligned plate boundaries (e.g., strike-slip margins non-parallel to plate motion), oblique subduction, and highly localized, weak and long lived acute plate-boundary junctions such as at what is observed at the Aleutian-Kurile intersection. The grain-damage and pinning

  2. Seismic Probing of the Base of a Tectonic Plate from Subduction Zone to Trench Outer Rise: Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Louie, J. N.; Kent, G. M.; Lamb, S. H.; Savage, M. K.; Stern, T. A.; Stratford, W. R.

    2015-12-01

    The nature of the base of a tectonic plate (LAB) is the 3rd dimension of plate tectonics. Recent seismic studies of the LAB have revealed planar features that show very different characteristics. In the oceans, the top of the S-wave low velocity zone shows a systematic deepening with plate age that fits plate-cooling models. However, the change in radial anisotropy has a markedly constant depth of ~70 km, regardless of plate age. A recent land-based study (SAHKE 2) of the subducted Pacific Plate in the southern Hikurangi margin has imaged a pair of distinct reflectors defining a ~10 km thick channel parallel to and ~70 km below the top of the ~15° dipping plate. Low velocities indicate that the channel is a zone of partial melt or high volatile content, acting as a weak base to the plate. Receiver function studies along the Japan margin have also imaged layers at these depths, parallel to the top of the plate and dipping up to 45°. We propose probing the base of the tectonic plate by tracing potential LAB seismic reflectors from their dipping portions in the subduction zone to where they bend in the trench outer rise. If the seismically identified boundary represents a 'frozen-in' feature, created at the mid ocean ridge, then it will remain parallel to the top of the plate, and its nature will remain unchanged as it is tracked over the outer rise. Alternatively, if the base of the plate is a thin channel of partial melt, then one would expect thickening of the channel beneath the outer rise due to melt ponding in the core of the flexure; this melt ponding may be the source of volcanic activity. A 500-km survey will trace the Pacific plate LAB from the subduction zone into the trench outer rise. The deeper part of the line coincides with the part of the plate where the ~10 km thick 'melt' channel was clearly imaged with the SAHKE 2 experiment. We show with synthetic experiments that given seismic energy scatter and attenuation comparable to that observed in the

  3. The memory of the accreting plate boundary and the continuity of fracture zones

    USGS Publications Warehouse

    Schouten, Hans; Klitgord, Kim D.

    1982-01-01

    A detailed aeromagnetic anomaly map of the Mesozoic seafloor-spreading lineations southwest of Bermuda reveals the dominant magnetic grain of the oceanic crust and the character of the accreting boundary at the time of crustal formation. The magnetic anomaly pattern is that of a series of elongate lobes perpendicular to the fracture zone (flowline) trends. The linear sets of magnetic anomaly peaks and troughs have narrow regions of reduced amplitude anomalies associated with the fracture zones. During the period of Mesozoic geomagnetic polarity reversals (when 1200 km of central North Atlantic seafloor formed), the Atlantic accreting boundary consisted of stationary, elongate, spreading center cells that maintained their independence even though sometimes only minor spatial offsets existed between cells. Normal oceanic crustal structure was formed in the spreading center cells, but structural anomalies and discontinuities characteristic of fracture zones were formed at their boundaries, which parallel flowlines of Mesozoic relative plate motion in the central North Atlantic. We suggest that the memory for a stationary pattern of independent spreading center cells resides in the young brittle lithosphere at the accreting boundary where the lithosphere is weakest; here, each spreading center cell independently goes through its cylce of stress buildup, stress release, and crustal accretion, after which its memory is refreshed. The temporal offset between the peaks of the accretionary activity that takes place within each cell may provide the mechanism for maintaining the independence of adjacent spreading center cells through times when no spatial offset between the cells exists.

  4. Direct Imaging Searches with the Apodizing Phase Plate Coronagraph

    NASA Astrophysics Data System (ADS)

    Kenworthy, M.; Meshkat, T.; Otten, , G.; Codona, J.

    2014-03-01

    The sensitivity of direct imaging searches for extrasolar planets is limited by the presence of diffraction rings from the primary star. Coronagraphs are angular filters that minimise these diffraction structures whilst allowing light from faint companions to shine through. The Apodizing Phase Plate (APP; Kenworthy 2007) coronagraph is a simple pupil plane optic that suppresses diffraction over a 180 degree region around each star simultaneously, providing easy beam switching observations and requiring no time consuming optical alignment at the telescope. We will present our results on using the APP at the Very Large Telescope in surveys for extrasolar planets around A/F and debris disk hosting stars in the L' band (3.8 microns) in the Southern Hemisphere, where we reach a contrast of 12 magnitudes at 0.5 arcseconds (Meshkat 2013). In Leiden, we are also developing the next generation of broadband achromatic coronagraphs that can simultaneously image both sides of the star using Vector APPs (Snik 2012, Otten 2012). Recent laboratory results showing the potential of this technology for future ELTs will also be presented.

  5. Wave transfer matrix for a spiral phase plate.

    PubMed

    Rumala, Yisa S

    2015-05-10

    The wave transfer matrix (WTM) is applied to calculating various characteristics of a spiral phase plate (SPP) for the first time to our knowledge. This approach provides a more convenient and systematic approach to calculating properties of a multilayered SPP device. In particular, it predicts the optical wave characteristics on the input and output plane of the device when the SPP is fabricated on a substrate of the same refractive index as the SPP as well as on a substrate of a different refractive index compared to the SPP. The dependence of the parameters on the input laser frequency is studied in detail for a low finesse SPP etalon device for both cases. The equations derived from the WTM are used to show that a variation in input laser frequency causes the optical intensity pattern on the output plane to rotate, while preserving the topology of the optical vortex, i.e., the variation in laser frequency has a minimal effect on the parameters describing the azimuthal intensity modulation and orbital angular momentum content of the beam. In addition, the equations predict the presence of longitudinal modes in the SPP device. PMID:25967494

  6. Construction of semi-dynamic model of subduction zone with given plate kinematics in 3D sphere

    NASA Astrophysics Data System (ADS)

    Morishige, M.; Honda, S.; Tackley, P. J.

    2010-09-01

    We present a semi-dynamic subduction zone model in a three-dimensional spherical shell. In this model, velocity is imposed on the top surface and in a small three-dimensional region around the shallow plate boundary while below this region, the slab is able to subduct under its own weight. Surface plate velocities are given by Euler's theorem of rigid plate rotation on a sphere. The velocity imposed in the region around the plate boundary is determined so that mass conservation inside the region is satisfied. A kinematic trench migration can be easily incorporated in this model. As an application of this model, mantle flow around slab edges is considered, and we find that the effect of Earth curvature is small by comparing our model with a similar one in a rectangular box, at least for the parameters used in this study. As a second application of the model, mantle flow around a plate junction is studied, and we find the existence of mantle return flow perpendicular to the plate boundary. Since this model can naturally incorporate the spherical geometry and plate movement on the sphere, it is useful for studying a specific subduction zone where the plate kinematics is well constrained.

  7. Dynamics of intraoceanic subduction initiation: 2. Suprasubduction zone ophiolite formation and metamorphic sole exhumation in context of absolute plate motions

    NASA Astrophysics Data System (ADS)

    van Hinsbergen, Douwe J. J.; Peters, Kalijn; Maffione, Marco; Spakman, Wim; Guilmette, Carl; Thieulot, Cedric; Plümper, Oliver; Gürer, Derya; Brouwer, Fraukje M.; Aldanmaz, Ercan; Kaymakcı, Nuretdin

    2015-06-01

    Analyzing subduction initiation is key for understanding the coupling between plate tectonics and the underlying mantle. Here we focus on suprasubduction zone (SSZ) ophiolites and how their formation links to intraoceanic subduction initiation in an absolute plate motion frame. SSZ ophiolites form the majority of exposed oceanic lithosphere fragments and are widely recognized to have formed during intraoceanic subduction initiation. Structural, petrological, geochemical, and plate kinematic constraints on their kinematic evolution show that SSZ crust forms at fore-arc spreading centers at the expense of a mantle wedge, thereby flattening the nascent slab. This leads to the typical inverted pressure gradients found in metamorphic soles that form at the subduction plate contact below and during SSZ crust crystallization. Former spreading centers are preserved in forearcs when subduction initiates along transform faults or off-ridge oceanic detachments. We show how these are reactivated when subduction initiates in the absolute plate motion direction of the inverting weakness zone. Upon inception of slab pull due to, e.g., eclogitization, the sole is separated from the slab, remains welded to the thinned overriding plate lithosphere, and can become intruded by mafic dikes upon asthenospheric influx into the mantle wedge. We propound that most ophiolites thus formed under special geodynamic circumstances and may not be representative of normal oceanic crust. Our study highlights how far-field geodynamic processes and absolute plate motions may force intraoceanic subduction initiation as key toward advancing our understanding of the entire plate tectonic cycle.

  8. Tectonic lineaments in the cenozoic volcanics of southern Guatemala: Evidence for a broad continental plate boundary zone

    NASA Technical Reports Server (NTRS)

    Baltuck, M.; Dixon, T. H.

    1984-01-01

    The northern Caribbean plate boundary has been undergoing left lateral strike slip motion since middle Tertiary time. The western part of the boundary occurs in a complex tectonic zone in the continental crust of Guatemala and southernmost Mexico, along the Chixoy-Polochic, Motogua and possibly Jocotan-Chamelecon faults. Prominent lineaments visible in radar imagery in the Neogene volcanic belt of southern Guatemala and western El Salvador were mapped and interpreted to suggest southwest extensions of this already broad plate boundary zone. Because these extensions can be traced beneath Quaternary volcanic cover, it is thought that this newly mapped fault zone is active and is accommodating some of the strain related to motion between the North American and Caribbean plates. Onshore exposures of the Motoqua-Polochic fault systems are characterized by abundant, tectonically emplaced ultramafic rocks. A similar mode of emplacement for these off shore ultramafics, is suggested.

  9. Predicting Earthquake Occurrence at Subduction-Zone Plate Boundaries Through Advanced Computer Simulation

    NASA Astrophysics Data System (ADS)

    Matsu'Ura, M.; Hashimoto, C.; Fukuyama, E.

    2004-12-01

    In general, predicting the occurrence of earthquakes is very difficult, because of the complexity of actual faults and nonlinear interaction between them. From the standpoint of earthquake prediction, however, our target is limited to the large events that completely break down a seismogenic zone. To such large events we may apply the concept of the earthquake cycle. The entire process of earthquake generation cycles generally consists of tectonic loading due to relative plate motion, quasi-static rupture nucleation, dynamic rupture propagation and stop, and restoration of fault strength. This process can be completely described by a coupled nonlinear system, which consists of an elastic/viscoelastic slip-response function that relates fault slip to shear stress change and a fault constitutive law that prescribes change in shear strength with fault slip and contact time. The shear stress and the shear strength are related with each other through boundary conditions on the fault. The driving force of this system is observed relative plate motion. The system to describe the earthquake generation cycle is conceptually quite simple. The complexity in practical modeling mainly comes from complexity in structure of the real earth. Recently, we have developed a physics-based, predictive simulation system for earthquake generation at plate boundaries in and around Japan, where the four plates of Pacific, North American, Philippine Sea and Eurasian are interacting with each other. The simulation system consists of a crust-mantle structure model, a quasi-static tectonic loading model, and a dynamic rupture propagation model. First, we constructed a realistic 3D model of plate interfaces in and around Japan by applying an inversion technique to ISC hypocenter data, and computed viscoelastic slip-response functions for this structure model. Second, we introduced the slip- and time-dependent fault constitutive law with an inherent strength-restoration mechanism as a basic

  10. Large area x-ray collimator-the zone plate approach.

    PubMed

    Menz, Benedikt; Braig, Christoph; Bräuninger, Heinrich; Burwitz, Vadim; Hartner, Gisela; Predehl, Peter

    2015-09-10

    One question of particular interest in the measurement of x-ray imaging optics for space telescopes concerns the characteristics of the point spread function (PSF) in orbit and the focal length for an infinite source distance. In order to measure such a PSF, a parallel x-ray beam with a diameter of several centimeters to meters is required. For this purpose a large area transmission x-ray zone plate (ZP) for collimating x-ray beams has been designed, built, and tested. Furthermore we present a setup to determine large-scale aberrations of the collimated beam. From x-ray measurements we obtain an upper limit for the angular resolution of ±0.2 arc sec and a first-order diffraction efficiency of ≈13%. These results show that it is possible to use a ZP as a collimator for the PANTER x-ray test facility. PMID:26368954

  11. Fluorescence microscopy imaging with a Fresnel zone plate array based optofluidic microscope

    PubMed Central

    Han, Chao; Lee, Lap Man; Yang, Changhuei

    2013-01-01

    We report the implementation of an on-chip microscope system, termed fluorescence optofluidic microscope (FOFM), which is capable of fluorescence microscopy imaging of samples in fluid media. The FOFM employs an array of Fresnel zone plates (FZP) to generate an array of focused light spots within a microfluidic channel. As a sample flows through the channel and across the array of focused light spots, the fluorescence emissions are collected by a filter-coated CMOS sensor, which serves as the channel's floor. The collected data can then be processed to render fluorescence microscopy images at a resolution determined by the focused light spot size (experimentally measured as 0.65 μm FWHM). In our experiments, our established resolution was 1.0 μm due to Nyquist criterion consideration. As a demonstration, we show that such a system can be used to image the cell nuclei stained by Acridine Orange and cytoplasm labeled by Qtracker®. PMID:21935556

  12. Digital in-line X-ray holography with zone plates.

    PubMed

    Heine, R; Gorniak, T; Nisius, T; Christophis, C; Pettitt, M E; Staier, F; Wilhein, T; Rehbein, S; Grunze, M; Rosenhahn, A

    2011-07-01

    Single pulse imaging with radiation provided by free-electron laser sources is a promising approach towards X-ray microscopy, which is expected to provide high resolution images of biological samples unaffected by radiation damage. One fully coherent imaging technique for this purpose is digital in-line holography. Key to its successful application is the creation of X-ray point sources with high photon flux. In this study we applied zone plates to create such point sources with synchrotron radiation provided by the storage ring BESSY II. The obtained, divergent light cone is applied to holographic microscopy of biological objects such as critical point dried Navicula perminuta diatoms and human cells using photons with an energy of 250 eV. Compared to conventional experiments employing pinholes, exposure times are reduced by two orders of magnitude. PMID:21740876

  13. Extension and transtension in the plate boundary zone of the northeastern Caribbean

    SciTech Connect

    Speed, R.C. ); Larue, D.K. )

    1991-03-01

    The authors propose that the Caribbean (Ca)-North American (NA) plate boundary zone (pbz) from the Puerto Rico Trench to the Venezuelan Basin from Mona Canyon east has been in left-transtension over the last 15-20 ma. A boundary-normal component of extension occurs throughout the pbz and is a principal cause of the Puerto Rico Trench. Such extension is due to WNW velocity of NA-Ca and the northward pullaway of NA from its S-dipping slab, which is below Puerto Rico. Strike slip motion may be taken up among terranes in the pbz by rigid CCW rotation and by oblique slip at their boundaries. Rotation of the largest terrane, Puerto Rico-Virgin Islands (PRVI), has caused such major structures as the Muertos thrust and Anegada Passage. The model implies NA-Ca velocity estimated from Cayman transforms is more accurate than that from slip vectors from seisms in the NA slab.

  14. Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

    NASA Astrophysics Data System (ADS)

    David, C.; Gorelick, S.; Rutishauser, S.; Krzywinski, J.; Vila-Comamala, J.; Guzenko, V. A.; Bunk, O.; Färm, E.; Ritala, M.; Cammarata, M.; Fritz, D. M.; Barrett, R.; Samoylova, L.; Grünert, J.; Sinn, H.

    2011-08-01

    A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×1017 W/cm2 was obtained at 70 fs pulse length.

  15. Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates.

    PubMed

    David, C; Gorelick, S; Rutishauser, S; Krzywinski, J; Vila-Comamala, J; Guzenko, V A; Bunk, O; Färm, E; Ritala, M; Cammarata, M; Fritz, D M; Barrett, R; Samoylova, L; Grünert, J; Sinn, H

    2011-01-01

    A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×10(17)W/cm(2) was obtained at 70 fs pulse length. PMID:22355576

  16. Long-term CGPS Measurements (1995-2008) in the Hellenic Deformation Zone Between the Eurasian and African Plates

    NASA Astrophysics Data System (ADS)

    Kahle, H.; Mueller, M. D.; Geiger, A.; Veis, G.; Billiris, H.; Paradissis, D.; Felekis, S.; Galanis, D.

    2008-12-01

    The Eastern Mediterranean forms the seismically most active region of the Alpine-Mediterranean plate boundary. It is characterized by the collision between the Eurasian and African plates. The collision is closely related to continental subduction and formation of the pronounced Hellenic trench system. In addition to the relatively slow CCW rotation of the African plate, rapid motion of the Anatolian-Aegean region is encountered, directed towards west-southwest, reaching velocities of up to 4 cm/yr along the Hellenic arc, relative to Eurasia. A long-term record of continuous GPS (CGPS) time series (1995-2008) and campaign- type GPS measurements (1991-2008) will be presented. The data has been analyzed to derive rates of plate and microplate motion and to study the strain rate field in the deforming zone between the Eurasian and African plates. This includes the deformation belt extending from the Ionian islands to the North Aegean Sea, Greece. While the Ionian islands are characterized by the Kephalonia fault zone which terminates the subduction of the Hellenic arc the most important feature in the North Aegean sea is the North Aegean trough which is considered to form the western continuation of the North Anatolian Fault Zone. Most recent GPS results will be presented for both regions and discussed in terms of ongoing deformation processes including dextral faulting and transtension, encountered in the northern Hellenic boundary region between the Eurasian and African plates.

  17. Defect detection in anisotropic plates based on the instantaneous phase of signals.

    PubMed

    Prado, Vander Teixeira; Granja, Silvio Cesar Garcia; Higuti, Ricardo Tokio; Kitano, Cláudio; Martínez-Graullera, Óscar; Segura, Luis Elvira

    2015-10-01

    Anisotropic materials are widely employed in industry and engineering, and efficient nondestructive testing techniques are important to guarantee the structural integrity of the involved parts. A simple technique is proposed to detect defects in anisotropic plates using ultrasonic guided waves and arrays. The technique is based on the application of an objective threshold to a synthetic aperture image obtained from the instantaneous phase (IP) of the emitter-receiver signal combinations. In a previous work the method was evaluated for isotropic materials, and in this paper it is shown that with some considerations the technique can also be applied to anisotropic plates. These considerations, which should be taken into account in beamforming, are (1) group velocity dependence with propagation direction, and (2) elastic focusing, which results in energy concentration in some propagation directions, with the practical consequence that not all aperture signals effectively contribute to the image. When compared with conventional delay-and-sum image beamforming techniques, the proposed IP technique results in significant improvements relative to defect detection and artifacts/dead zone reduction. PMID:26470050

  18. Generation of adakites in a cold subduction zone due to double subducting plates

    NASA Astrophysics Data System (ADS)

    Nakamura, Hitomi; Iwamori, Hikaru

    2013-06-01

    Adakites have been found in various tectonic settings, since the first report for the distinct lavas as a product of slab melting in Adak Island by Kay (J Volcanol Geotherm Res 4:117-132, 1978). In this study, we present geochemical data for an `adakite' and `adakitic rock' suite in central Japan with a cold subduction environment due to the two overlapping subducting plates: the Pacific plate and the Philippine sea plate. Based on the major, trace and isotopic compositions of the rocks, elemental transport from initial slab inventory at the trench to the volcanic rocks as a final product is quantitatively analyzed, considering the thermal structure, slab dehydration, elemental mobility, slab-fluid migration and melting of fluid-added mantle. The analysis demonstrates a large compositional impact of slab-fluid in the arc magma generation in central Japan. The melting conditions have been also estimated inversely by optimizing the predicted magma composition to the observed composition of volcanic rock, with the two parameters: the degree of melting and the proportion of spinel and garnet lherzolites involved in melting. Consequently, a moderately low degree of near-solidus melting of dominantly garnet lherzolite with a high fluid flux from the two overlapping slabs beneath the region has been argued to be responsible for the compositional characteristics, including the adakitic signatures, of the studied rocks. These results imply that the geochemical approach may provide useful constraints on the P- T condition of melting in the mantle wedge and the thermal structure in subduction zones, being complementary to the geophysical approach.

  19. Carbonatite melt infiltration in mantle xenoliths from the Eurasian plate - North American modern plate collision zone (Ruditch, Yakutia)

    NASA Astrophysics Data System (ADS)

    Tschegg, Cornelius; Ntaflos, Theodoros; Akinin, Viacheslav; Hauzenberger, Christoph

    2010-05-01

    Within the seismic active Chersky belt, the modern border between North American and Eurasian plates (Indigirka River area, Sakha-Yakutia Republic), mantle xenoliths were found in eroded alkaline basalt dike remnants.The peridotite xenoliths are represented by mainly anhydrous spinel lherzolites that appear together with subordinate orthpyroxene, clinopyroxene and feldspar megacrysts. Spinel lherzolites have protogranular textures and are well equilibrated, lacking any mineral zonation. The constituent minerals have minor compositional variations whithin and between different samples. Olivine compositions range from Fo 89-90.5, with CaO contents between 0.04 and 0.06 wt.%. Orthopyroxenes indicate a very narrow composititional variance (Wo1En63Fs36, Mg# 90-91 and Al2O3 from 4 to 4.7 wt.%), just like clinopyroxene phases that are represented by Wo38En40Fs22, with Mg#s from 90 to 91 and Al2O3 between 6.8 and 7.6 wt.%. Spinels also show a fertile composition with Cr#s ranging between 26 and 29 and Mg#s between 77 and 78 respectively. Equlibration temperature estimations gives approx. 1000 °C at 15 kbar pressure for all studied samples. In one xenolith, a round melt pocket with 200 microns in diameter consisting of well crystallized dolomite (25 wt.% CaO, 31 wt.% MgO) in perfect contact with homogeneous glass (16 wt.% Na2O, 51 wt.% SiO2, 20 wt.% Al2O3), apparently an immiscibility of carbonatite and silicate melt, was found at the triple point of olivine, orthopyroxene and clinopyroxene. Mineral chemistries show that the lithospheric mantle underneath the study area is a fertile lherzolith. Clinopyroxene LA-ICP-MS trace element analyses confirm the fertile nature of the xenoliths. The primitive mantle normalized REE patterns show a slight depletion of LREE with respect to HREE. The majority of the analyzed cpx have (La/Yb)N that vary between 0.1 and 0.5 and (Tb/Yb)N from 1.0 to 1.1 indicating the overal absense and metasomatic processes and low degree of melt

  20. Pinhole diffraction holography for fabrication of high-resolution Fresnel zone plates.

    PubMed

    Sarkar, Sankha S; Solak, Harun H; David, Christian; van der Veen, J Friso

    2014-01-27

    Fresnel zone plates (FZPs) play an essential role in high spatial resolution x-ray imaging and analysis of materials in many fields. These diffractive lenses are commonly made by serial writing techniques such as electron beam or focused ion beam lithography. Here we show that pinhole diffraction holography has potential to generate FZP patterns that are free from aberrations and imperfections that may be present in alternative fabrication techniques. In this presented method, FZPs are fabricated by recording interference pattern of a spherical wave generated by diffraction through a pinhole, illuminated with coherent plane wave at extreme ultraviolet (EUV) wavelength. Fundamental and practical issues involved in formation and recording of the interference pattern are considered. It is found that resolution of the produced FZP is directly related to the diameter of the pinhole used and the pinhole size cannot be made arbitrarily small as the transmission of EUV or x-ray light through small pinholes diminishes due to poor refractive index contrast found between materials in these spectral ranges. We also find that the practical restrictions on exposure time due to the light intensity available from current sources directly imposes a limit on the number of zones that can be printed with this method. Therefore a trade-off between the resolution and the FZP diameter exists. Overall, we find that this method can be used to fabricate aberration free FZPs down to a resolution of about 10 nm. PMID:24515148

  1. Direct-write X-ray lithography using a hard X-ray Fresnel zone plate.

    PubMed

    Lee, Su Yong; Noh, Do Young; Lee, Hae Cheol; Yu, Chung-Jong; Hwu, Yeukuang; Kang, Hyon Chol

    2015-05-01

    Results are reported of direct-write X-ray lithography using a hard X-ray beam focused by a Fresnel zone plate with an outermost zone width of 40 nm. An X-ray beam at 7.5 keV focused to a nano-spot was employed to write arbitrary patterns on a photoresist thin film with a resolution better than 25 nm. The resulting pattern dimension depended significantly on the kind of underlying substrate, which was attributed to the lateral spread of electrons generated during X-ray irradiation. The proximity effect originated from the diffuse scattering near the focus and electron blur was also observed, which led to an increase in pattern dimension. Since focusing hard X-rays to below a 10 nm spot is currently available, the direct-write hard X-ray lithography developed in this work has the potential to be a promising future lithographic method. PMID:25931097

  2. Multilayer on-chip stacked Fresnel zone plates: Hard x-ray fabrication and soft x-ray simulations

    SciTech Connect

    Li, Kenan; Wojcik, Michael J.; Ocola, Leonidas E.; Divan, Ralu; Jacobsen, Chris

    2015-11-01

    Fresnel zone plates are widely used as x-ray nanofocusing optics. To achieve high spatial resolution combined with good focusing efficiency, high aspect ratio nanolithography is required, and one way to achieve that is through multiple e-beam lithography writing steps to achieve on-chip stacking. A two-step writing process producing 50 nm finest zone width at a zone thickness of 1.14 µm for possible hard x-ray applications is shown here. The authors also consider in simulations the case of soft x-ray focusing where the zone thickness might exceed the depth of focus. In this case, the authors compare on-chip stacking with, and without, adjustment of zone positions and show that the offset zones lead to improved focusing efficiency. The simulations were carried out using a multislice propagation method employing Hankel transforms.

  3. Seismological investigations of the subduction zone plate interface: New advances and challenges

    NASA Astrophysics Data System (ADS)

    Rietbrock, Andreas; Garth, Tom; Hicks, Stephen

    2015-04-01

    In the last decade, huge advances have been made in analysing the slip distribution of large megathrust earthquakes and how slip relates to geodetic locking, shedding light on the character of the seismic cycle in subduction zones. Recently, a number of studies have suggested that at convergent plate boundaries, geodetic locking may be closely related to slip distribution of subsequent large earthquakes, as found recently for the Maule 2010 and Tohoku 2011 earthquakes. However, the physical (e.g. seismic) properties along the subduction zone interface are still poorly constrained, posing a major limitation to our physical understanding of both geodetic locking and earthquake rupture process. Here, we present high-resolution seismic tomography results (P- and S-wave velocity), as well as earthquake locations to make a detailed investigation of seismic properties along the portion of the plate interface that ruptured during the 2010 Maule earthquake. Additionally, to test the robustness of our models, we performed numerous numerical tests including changes to the parameterization, synthetic recovery tests and bootstrap analysis. We find P-wave velocities of about 5.7 km/s at 10 km depth and linearly increasing to 7.5 km/s at a depth of 30 km. Between 30 km and 43 km, P-wave velocities are relatively constant at around 7.5 km/s before a subsequent increase to 8.3 km/s at larger depths (>60 km) is observed. The Poisson's ratio is significantly elevated, at values of up to 0.35 at shallow depths of 10km to 15km, before reaching less elevated values of 0.28-0.29 in the depth range between 20km and 43km. Comparison of these velocities to petrological models shows good agreement below 30 - 50 km depth. At shallower depths though P-wave velocities are significantly lower, which together with the elevated poisons ratio indicates that this portion of the mega thrust is highly hydrated, suggesting that material properties may in part control the seismogenic character of

  4. Calibration and Performance Modeling of Free-Standing Zone Plates for Extreme Ultraviolet Solar Radiometry having High Accuracy and Stability in Space

    NASA Astrophysics Data System (ADS)

    McMullin, D. R.; Seely, J. F.; Vest, R.; Chang, C.; Sakdinawat, A.; Bremer, J.; Jones, A. R.

    2014-12-01

    Free-standing zone plates for use in EUV solar radiometers were fabricated using electron beam lithography and calibrated at the NIST SURF synchrotron facility. The measured efficiencies are compared to the calculated values. The free-standing zone plate, a binary zone plate consisting of open spaces and interconnected Au opaque bars, has the advantage that a support membrane is not required, resulting in excellent long-term stability in space against contamination, radiation damage, and other effects that could alter the efficiency and instrument throughput. The interconnections of the zones are designed as a robust open mesh of the same type that supports transmission gratings in current spaceflight instruments. The 4 mm outer diameter of the zone plate and compact size of the optical train make these zone plates attractive for small CubeSats and other space flight missions where resources are extremely limited.

  5. Seismic structure of the North Pacific oceanic crust prior plate bending at the Alaska subduction zone

    NASA Astrophysics Data System (ADS)

    Becel, A.; Shillington, D. J.; Nedimovic, M. R.; Kuehn, H.; Webb, S. C.; Holtzman, B. K.

    2012-12-01

    Seismic reflection profiles across North Pacific oceanic Plate reveal the internal structure of a mature oceanic crust (42-56Ma) formed at fast (70mm/yr, half rate) to intermediate (28mm/yr, half rate) spreading rates. Data used in this study were collected with the R/V Langseth in summer 2011 as part of the ALEUT (Alaska Langseth Experiment to Understand the megathrust) program. MCS data were acquired with two 8-km streamers and a 6600 cu. in. air gun array. We collected a series of profiles across the subduction zone system but also across the preexisting structures of the oceanic crust before being affected by subduction zone processes. Additionally, two 400-km OBS refraction lines were shot coincident with MCS profiles. The multi-channel seismic (MCS) data across oceanic crust formed at fast spreading rates contain abundant bright reflectors mostly confined in the lower crust above the Moho discontinuity and dipping predominantly toward the paleo-ridge. Along these profiles, the Moho discontinuity is observed as a bright event with remarkable lateral continuity. The lengths of the dipping reflectors are on the order of 5-km, with apparent dips between 10 and 30°. These reflectors represent discrete events, with spacing between 0.3 to 5 km without any obvious regularity. These dipping events appear to sole out within the middle crust (1 to 1.5 s beneath basement) and most of them terminate at the Moho. The Moho is much weaker or absent on the northern profiles acquired across the North Pacific oceanic crust formed at intermediate spreading rates. Basement topography is rougher and no clear dipping events have been imaged suggesting that the spreading rate may be an important factor that controls the strength and abundance of such dipping reflectors and the lateral change in the Moho reflection characters. Lower crustal dipping reflections (LCDR) have been only imaged at very few places across the Pacific oceanic crust: (Eittreim et al., 1988, Reston et al. 1999

  6. 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.

  7. Light-Weight, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    SciTech Connect

    Narumanchi, S.

    2013-07-01

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  8. Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    SciTech Connect

    Narumanchi, S.

    2013-07-01

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  9. Cryo-EM single particle analysis with the Volta phase plate

    PubMed Central

    Danev, Radostin; Baumeister, Wolfgang

    2016-01-01

    We present a method for in-focus data acquisition with a phase plate that enables near-atomic resolution single particle reconstructions. Accurate focusing is the determining factor for obtaining high quality data. A double-area focusing strategy was implemented in order to achieve the required precision. With this approach we obtained a 3.2 Å resolution reconstruction of the Thermoplasma acidophilum 20S proteasome. The phase plate matches or slightly exceeds the performance of the conventional defocus approach. Spherical aberration becomes a limiting factor for achieving resolutions below 3 Å with in-focus phase plate images. The phase plate could enable single particle analysis of challenging samples in terms of small size, heterogeneity and flexibility that are difficult to solve by the conventional defocus approach. DOI: http://dx.doi.org/10.7554/eLife.13046.001 PMID:26949259

  10. Cryo-EM single particle analysis with the Volta phase plate.

    PubMed

    Danev, Radostin; Baumeister, Wolfgang

    2016-01-01

    We present a method for in-focus data acquisition with a phase plate that enables near-atomic resolution single particle reconstructions. Accurate focusing is the determining factor for obtaining high quality data. A double-area focusing strategy was implemented in order to achieve the required precision. With this approach we obtained a 3.2 Å resolution reconstruction of the Thermoplasma acidophilum 20S proteasome. The phase plate matches or slightly exceeds the performance of the conventional defocus approach. Spherical aberration becomes a limiting factor for achieving resolutions below 3 Å with in-focus phase plate images. The phase plate could enable single particle analysis of challenging samples in terms of small size, heterogeneity and flexibility that are difficult to solve by the conventional defocus approach. PMID:26949259

  11. Anisotropic pure-phase plates for quality improvement of partially coherent, partially polarized beams.

    PubMed

    Martínez-Herrero, Rosario; Mejías, Pedro M; Piquero, Gemma

    2003-03-01

    From a theoretical point of view, the use of anisotropic pure-phase plates (APP) is considered in order to improve the quality parameter of certain partially coherent, partially polarized beams. It is shown that, to optimize the beam-quality parameter, the phases of the two Cartesian components of the field at the output of the APP plate should be identical and should exhibit a quadratic dependence on the radial polar coordinate. PMID:12630845

  12. Anisotropic pure-phase plates for quality improvement of partially coherent, partially polarized beams

    NASA Astrophysics Data System (ADS)

    MartíNez-Herrero, Rosario; MejíAs, Pedro M.; Piquero, Gemma

    2003-03-01

    From a theoretical point of view, the use of anisotropic pure-phase plates (APP) is considered in order to improve the quality parameter of certain partially coherent, partially polarized beams. It is shown that, to optimize the beam-quality parameter, the phases of the two Cartesian components of the field at the output of the APP plate should be identical and should exhibit a quadratic dependence on the radial polar coordinate.

  13. 2D Dynamic Models of Subduction: Links between Surface Plate Motion and Deformation in the Transition Zone from Observations of Deep Slab Seismicity

    NASA Astrophysics Data System (ADS)

    Arredondo, K.; Billen, M. I.

    2015-12-01

    Observations of seismicity and seismic tomography provide constraints on the geometry of slabs within mantle, while compression/tension axis derived from moment tensor solutions provide constraints on the internal deformation of slabs. However, since these observations provide only a somewhat blurred or incomplete snapshot of the slab in time, it is difficult to directly relate these observations to the evolution of the slab geometry and the forces acting on and within the slab. In contrast, plate tectonic reconstructions provide time-dependent constraints on the surface motion of plates and the trench at subduction zones, which are related to the dynamical evolution of the slab. We use 2D geodynamical simulations of subduction to explore the relationship between dynamical process within the deforming slab and the observations of surface plate motion and the state-of-stress in slabs. Specifically we utilize models that include the extended Boussinesq approximation (shear heating and latent heat terms in the energy equation), a layered lithosphere with pyrolite, harzburgite and basalt/eclogite, compositionally-dependent phase transitions, and a composite rheology with yielding. The models employ a weak crustal layer that decouples the overriding and subducting plates and allows for dynamically determined trench motion. Here we show that, 1) multiple phase transitions increase slab folding, 2) ridge push significantly increases trench retreat, and 3) strength of the weak crustal layer influences slab detachment. Compared to past studies a more realistic treatment of the phase transitions makes trench retreat more difficult to generate: a weaker plate may encourage slab retreat but detaches once the slab tip crosses into the transition zone due to the rapid increase in slab density. As suggested by previous studies, slab folding within the transition zone changes the direction of forces on the slab and causes periodic changes from trench retreat to trench advance. We

  14. Characterisation of ferromagnetic rings for Zernike phase plates using the Aharonov-Bohm effect.

    PubMed

    Edgcombe, C J; Ionescu, A; Loudon, J C; Blackburn, A M; Kurebayashi, H; Barnes, C H W

    2012-09-01

    Holographic measurements on magnetised thin-film cobalt rings have demonstrated both onion and vortex states of magnetisation. For a ring in the vortex state, the difference between phases of electron paths that pass through the ring and those that travel outside it was found to agree very well with Aharonov-Bohm theory within measurement error. Thus the magnetic flux in thin-film rings of ferromagnetic material can provide the phase shift required for phase plates in transmission electron microscopy. When a ring of this type is used as a phase plate, scattered electrons will be intercepted over a radial range similar to the ring width. A cobalt ring of thickness 20 nm can produce a phase difference of π/2 from a width of just under 30 nm, suggesting that the range of radial interception for this type of phase plate can be correspondingly small. PMID:22842114

  15. Chromatic characterization of ion-exchanged glass binary phase plates for mode-division multiplexing.

    PubMed

    Prieto-Blanco, Xesús; Montero-Orille, Carlos; Moreno, Vicente; Mateo, Eduardo F; Liñares, Jesús

    2015-04-10

    Mode-division multiplexing (MDM) in few-mode fibers is regarded as a promising candidate to increase optical network capacity. A fundamental element for MDM is a modal transformer to LP modes which can be implemented in a free-space basis by using multiregion phase plates, that is, LP plates. Likewise, several wavelengths have to be used due to wavelength multiplexing purposes, optical amplification tasks, and so on. In this work we show that efficient monolithic binary phase plates for different wavelengths can be fabricated by ion-exchange in glass and used for MDM tasks. We introduce an optical characterization method of the chromatic properties of such phase plates which combines the inverse Wentzel-Kramers-Brillouin (IWKB) together with Mach-Zehnder and Michelson-based interferometric techniques. The interferometric method provides a measurement of the phase step for several wavelengths, which characterizes the chromatic properties of the phase plate. Consequently, it is shown that the IWKB method allows us to design and characterize the phase plates in an easy and fast way. PMID:25967318

  16. Is the Teisseyre-Tornquist Zone an ancient plate boundary of Baltica?

    NASA Astrophysics Data System (ADS)

    Mazur, Stanislaw; Mikolajczak, Mateusz; Krzywiec, Piotr; Malinowski, Michal; Buffenmyer, Vinton; Lewandowski, Marek

    2015-12-01

    The Teisseyre-Tornquist Zone (TTZ) is generally regarded as a fossil plate boundary in Europe that extends 2000 km from the Baltic Sea to the Black Sea. We used an integrated approach merging potential fields and seismic data to explore crustal architecture across the TTZ in central Poland. The aim of the study was to test whether the TTZ coincides with an early Paleozoic (Caledonian) suture formed through the closure of the Tornquist Ocean along the SW Baltica margin. The suture is presumed to separate the East European Craton (EEC) from the Paleozoic terranes of Western Europe. Two seismic reflection lines from the PolandSPAN™ experiment were used to image the deep structure at the SW margin of the EEC. Lines PL-5300 and PL-5400 run NE-SW in central and northern Poland, respectively. The seismic interpretation down to top of basement was integrated with 2-D gravity and magnetic modeling to highlight the structure of the deep crust. Both the gravity and magnetic models show a suture that welds together two blocks at the base of crust. However, top of basement above the suture dips uniformly to the SW and is overlain by undisturbed lower Paleozoic and younger sediments. By implication, the suture must have developed in the Precambrian and both crustal blocks amalgamated belong to the EEC. Consequently, the Caledonian suture, formed by the closure of the Tornquist Ocean between Avalonia and Baltica, must be located farther southwest beneath thick upper Paleozoic and Mesozoic sediments.

  17. Hard X-ray imaging of Cyg X-1 using balloon borne Fresnel Zone plates imager

    NASA Astrophysics Data System (ADS)

    Manchanda, R. K.

    Imaging in hard X-rays above 20 keV is a well known technological challenge. Coded aperture mask have been used in the past, but these require position sensitive detectors. However, the scintillation counters which form the bulk of hard X-ray detectors as these offer high detection efficiency, do not have intrinsic position sensitivity. Pixilated solid state detectors CZT and CdTe are being developed as the detectors for imaging telescope with coded mask. Alternatively, a combination of Fresnel Zone Plates (FZP) can also be used for imaging in the hard X-ray band. We have developed a new imaging telescope using a pair of tungsten FZP and tiny hard X-ray imager, made with thin NaI(Tl) viewed by a position sensitive photomultiplier. The instrument was launched as a piggyback on the Large Area Scintillation counter Experiment (LASE) in a balloon flight conducted on April 25, 2008 and reached a ceiling altitude 2.8 mb. Cyg X-1, was observed during the flight to study the imaging efficacy of FZP imager. This paper describes the details of the experiment, digital reconstruction of the imaged data.

  18. The application of Fresnel zone plate based projection in optofluidic microscopy

    PubMed Central

    Wu, Jigang; Cui, Xiquan; Lee, Lap Man; Yang, Changhuei

    2009-01-01

    Optofluidic microscopy (OFM) is a novel technique for low-cost, high-resolution on-chip microscopy imaging. In this paper we report the use of the Fresnel zone plate (FZP) based projection in OFM as a cost-effective and compact means for projecting the transmission through an OFM's aperture array onto a sensor grid. We demonstrate this approach by employing a FZP (diameter = 255 μm, focal length = 800 μm) that has been patterned onto a glass slide to project the transmission from an array of apertures (diameter = 1 μm, separation = 10 μm) onto a CMOS sensor. We are able to resolve the contributions from 44 apertures on the sensor under the illumination from a HeNe laser (wavelength = 633 nm). The imaging quality of the FZP determines the effective field-of-view (related to the number of resolvable transmissions from apertures) but not the image resolution of such an OFM system – a key distinction from conventional microscope systems. We demonstrate the capability of the integrated system by flowing the protist Euglena gracilis across the aperture array microfluidically and performing OFM imaging of the samples. PMID:18825198

  19. The application of Fresnel zone plate based projection in optofluidic microscopy.

    PubMed

    Wu, Jigang; Cui, Xiquan; Lee, Lap Man; Yang, Changhuei

    2008-09-29

    Optofluidic microscopy (OFM) is a novel technique for low-cost, high-resolution on-chip microscopy imaging. In this paper we report the use of the Fresnel zone plate (FZP) based projection in OFM as a cost-effective and compact means for projecting the transmission through an OFM's aperture array onto a sensor grid. We demonstrate this approach by employing a FZP (diameter = 255 microm, focal length = 800 microm) that has been patterned onto a glass slide to project the transmission from an array of apertures (diameter = 1 microm, separation = 10 microm) onto a CMOS sensor. We are able to resolve the contributions from 44 apertures on the sensor under the illumination from a HeNe laser (wavelength = 633 nm). The imaging quality of the FZP determines the effective field-of-view (related to the number of resolvable transmissions from apertures) but not the image resolution of such an OFM system--a key distinction from conventional microscope systems. We demonstrate the capability of the integrated system by flowing the protist Euglena gracilis across the aperture array microfluidically and performing OFM imaging of the samples. PMID:18825198

  20. Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

    PubMed Central

    David, C.; Gorelick, S.; Rutishauser, S.; Krzywinski, J.; Vila-Comamala, J.; Guzenko, V. A.; Bunk, O.; Färm, E.; Ritala, M.; Cammarata, M.; Fritz, D. M.; Barrett, R.; Samoylova, L.; Grünert, J.; Sinn, H.

    2011-01-01

    A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×1017 W/cm2 was obtained at 70 fs pulse length. PMID:22355576

  1. On gravity from SST, geoid from SEASAT, and plate age and fracture zones in the Pacific

    NASA Technical Reports Server (NTRS)

    Marsh, B. D.; Marsh, J. G.; Williamson, R. G.

    1983-01-01

    Data from an additional 50 satellite-to-satellite tracking (SST) passes were combined with earlier measurements of the high degree and order (n, m, 12) gravity in the central Pacific. A composite map was produced which shows good agreement with conventional GEM models. Data from the SEASAT altimeter was reduced and found to agree well with both the SST and the GEM fields. The maps are dominated especially in the east, by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Further comparison with regional bathymetric data shows a remarkably close correlation with plate age. Each anomaly band is framed by those major fracture zones having large offsets. The regular spacing of these fractures seems to account for the fabric in the gravity fields. Other anomalies are accounted for by hot spots. The source of part of these anomalies is in the lithosphere itself. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantel without complete thermal equilibration is considered.

  2. Upper Plate Geology Controls the Rupture Area Segmentation of Subduction Zone Earthquake - A Case Study of the Nankai Trough

    NASA Astrophysics Data System (ADS)

    Kimura, G.; Hashimoto, Y.; Kitamura, Y.; Yamaguchi, A.; Hamahashi, M.; Koge, H.; Morita, S.

    2014-12-01

    What controls the earthquake rupture area of megathrust is one of the most fundamental questions in subduction zones. In the Nankai Trough, Japan, three major controlling factors have been proposed; surface topographic highs of the subducting plate such as seamounts, locally strong rigidity of upper plate, and friction property of the plate boundary megathrust with abnormal pore fluid pressure. For example, the topographic highs may control the location of asperity due to stronger coupling. The topographic highs also work as a barrier for rock deformation. From the geological point of view, plate boundary megathrust in the seismogenic zone must be composed of fault rock in the brittle regime because of its temperature range from ~150℃ to ~350℃. The friction behaviors of these fault rocks and the effects of abnormal pore fluid pressure are recently one of the major concerns. The third factor is the mechanical property of the upper plate. The property changes through geological time scale due to the growth of the accretionary prism or tectonic erosion. In the case of the Nankai Trough, a pultonic body is situated beneath the place of epicenter and is suggested to have been functioned as an asperity of 1944 and 1946 earthquakes. We examined the on-land geology of the Shikoku island and the Kii Peninsula, SW Japan, and their basement structure and composition beneath the forearc Kumano Basin. We conclude that middle to late Miocene episodic magmatic intrusion and extrusion now controls the rupture area segmentation of the great earthquakes in the Nankai Trough.

  3. Can Mantle Transition Zone beneath the Caroline Plate, Equatorial Western Pacific Be Resolved Seismologically Using Available Dataset?

    NASA Astrophysics Data System (ADS)

    Kang, H.; Konishi, K.; Lee, S. M.

    2014-12-01

    The Caroline Plate, located in the equatorial Western Pacific, appears to be underlain by a stagnant slab. Even though the plate is surrounded by seismic zones of deep- and intermediate-depth earthquakes (originating from the Philippines, Banda Sea, Mariana and New Britain Island), available seismic dataset of source-receiver pair is limited due to the scarcity of land-based seismic stations. In particular, seismic stations are limited in the western and eastern sides of the Caroline Plate. In this study, we perform investigations on the seismic resolution using waveform inversion approach. Earthquake data sets in the last decade obtained from publicly available seismic stations were used to examine the presumed mantle transition zone (MTZ), whose depth ranges from 410 to 660 km in three dimensions. Our analysis shows that, although the current coverage may be marginally sufficient to assess the presence or absence of stagnant slab, the number of ray paths, especially towards the equator, is too limited to obtain high-resolution three-dimensional structure. Hence, it is important to install additional seismic stations (most likely, in the form of the broadband ocean bottom seismometers) around the Caroline Plate. A number of optimal sites are suggested based on our resolution tests. It is hoped that by placing additional ocean bottom seismometers several important issues regarding the nature of MTZ beneath Caroline Plate can be explored that could not be addressed by global tomography models alone such as its origin.

  4. Oceanic plate weakened by flexural bending-induced faulting in the outer rise region of the Mariana subduction zone

    NASA Astrophysics Data System (ADS)

    Zhang, F.; Lin, J.; Zhan, W.

    2013-12-01

    Strong flexural bending near trenches could significantly weaken oceanic plates through development of trench-parallel extensional normal faults. We assessed the oceanic plate weakening near the outer rise region of the Mariana subduction zone by analyzing and modeling the plate deformation caused by flexural bending. We first obtained a 3-D deformation surface of the subducting plate by removing from seafloor bathymetry the topographic effects of sediments, seamounts, and age-related thermal subsidence. We then calculated theoretical models of plate deformation and inverted for along-trench changes in the vertical force and bending moment at the trench axis, as well as spatial variations in the effective elastic thickness of the subducting plate, that best explain the observations. We found that to replicate simultaneously the observed steep slope of the seafloor near the trench axis and the long-wavelength flexural profiles seaward of the outer rise region, the effective elastic thickness of the plate must change significantly. The best-fitting models reveal that the effective elastic thickness is about 45-55 km seaward of the outer rise (TeMax), but is reduced to only 19-40 km trench-ward of the outer rise region (TeMin); the transition from TeMax to TeMin occurs at Xr =70-120 km away from the trench axis. The resultant reduction in the calculated effective elastic thickness, i.e., 1 - (TeMin /TeMax), is in the range of 20-60%, being the greatest near the Challenger Deep area, where the plate deforms significantly within a narrow distance from the trench axis and the trench axis is the deepest. Our results revealed that reduction in Te along the Mariana trench does not exceed 60%, implying that an elastic core remains in the subducting plate despite pervasive faulting caused by flexural bending near the trench axis.

  5. Slab Driven Plate Motions and Three-dimensional Mantle Flow Pathways in the Central American Subduction Zone

    NASA Astrophysics Data System (ADS)

    Jadamec, M. A.; Fischer, K. M.

    2014-12-01

    We present a series of three-dimensional (3D), high-resolution, end-member tectonic configurations of the Central American plate system and use these to solve for the 3D viscous mantle flow and surface plate motions. The 3D geodynamic models test the relative control of the viscosity structure (Newtonian versus Composite), subducting plate geometry (continuous slab versus Cocos-Nazca slab gap), and overriding plate thickness (uniform versus laterally variable) on the predicted motion of the Cocos and Nazca plates and the slab-induced 3D flow field in the upper mantle. Models using the composite viscosity formulation result in increased surface plate motions, which better fit the observed motion of the Cocos and Nazca plates. This is particularly significant because these 3D regional models contain the entire Cocos plate, suggesting the importance of the non-linear rheology in models that aim to predict surface plate motions. Faster flow velocities occur in models using the composite viscosity due to the decreased resistance to subduction and reduced viscous support of the slab as the mantle surrounding the slab undergoes non-linear weakening. A zone of partial decoupling between the uppermost mantle and lithosphere, thus, naturally develops due to the composite viscosity formulation. Models that include a gap between the Cocos and Nazca slabs better fit the mantle flow pathways interpreted from the geochemical signatures, as material is brought from beneath the Cocos plate around the slab edge and northward into the mantle wedge beneath Central America. The mantle-lithosphere decoupling is enhanced in models with the slab gap, wherein the mantle flow field contains both counter-clockwise toroidal flow around the Cocos slab edge and clockwise toroidal flow around the northern Nazca slab edge, both of which are non-parallel to surface motions. The models also demonstrate that overriding plate thickness places a control on both the predicted surface motion and

  6. Three-Phase Coexistence in Colloidal Rod-Plate Mixtures.

    PubMed

    Woolston, Phillip; van Duijneveldt, Jeroen S

    2015-09-01

    Aqueous suspensions of clay particles, such as montmorillonite (MMT) platelets and sepiolite (Sep) rods, tend to form gels at concentrations around 1 vol %. For Sep rods, adsorbing sodium polyacrylate to the surface allows for an isotropic-nematic phase separation to be seen instead. Here, MMT is added to such Sep suspensions, resulting in a complex phase behavior. Across a range of clay concentrations, separation into three phases is observed: a lower, nematic phase dominated by Sep rods, a MMT-rich middle layer, which is weakly birefringent and probably a gel, and a dilute top phase. Analysis of phase volumes suggests that the middle layer may contain as much as 6 vol % MMT. PMID:26262770

  7. Two-phase gas-liquid flow characteristics inside a plate heat exchanger

    SciTech Connect

    Nilpueng, Kitti; Wongwises, Somchai

    2010-11-15

    In the present study, the air-water two-phase flow characteristics including flow pattern and pressure drop inside a plate heat exchanger are experimentally investigated. A plate heat exchanger with single pass under the condition of counter flow is operated for the experiment. Three stainless steel commercial plates with a corrugated sinusoidal shape of unsymmetrical chevron angles of 55 and 10 are utilized for the pressure drop measurement. A transparent plate having the same configuration as the stainless steel plates is cast and used as a cover plate in order to observe the flow pattern inside the plate heat exchanger. The air-water mixture flow which is used as a cold stream is tested in vertical downward and upward flow. The results from the present experiment show that the annular-liquid bridge flow pattern appeared in both upward and downward flows. However, the bubbly flow pattern and the slug flow pattern are only found in upward flow and downward flow, respectively. The variation of the water and air velocity has a significant effect on the two-phase pressure drop. Based on the present data, a two-phase multiplier correlation is proposed for practical application. (author)

  8. Greenland Fracture Zone-East Greenland Ridge(s) revisited: Indications of a C22-change in plate motion?

    NASA Astrophysics Data System (ADS)

    DøSsing, A.; Funck, T.

    2012-01-01

    Changes in the lithospheric stress field, causing axial rift migration and reorientation of the transform, are generally proposed as an explanation for anomalously old crust and/or major aseismic valleys in oceanic ridge-transform-ridge settings. Similarly, transform migration of the Greenland Fracture Zone and separation of the 200-km-long, fracture-zone-parallel continental East Greenland Ridge from the Eurasia plate is thought to be related to a major change in relative plate motions between Greenland and Eurasia during the earliest Oligocene (Chron 13 time). This study presents a reinterpretation of the Greenland Fracture Zone - East Greenland Ridge based on new and existing geophysical data. Evidence is shown for two overstepping ridge segments (Segments A and B) of which Segment A corresponds to the already known East Greenland Ridge while Segment B was not detected previously. Interpretation of sonobuoy data and revised modeling of existing OBS data across Segment B indicate a continental composition of the segment. This interpretation is supported by magnetic anomaly data. The Segments A and B are bounded by portions of the Greenland Fracture Zone with a distinct ˜10° difference in strike. This is suggested to relate to an early episode of transform migration and reorientation of the lithospheric stress field around Chron 22 time, i.e., shortly after the Eocene breakup in the northern NE Atlantic. These findings contradict with previous interpretations of the fracture zone, which infer simple pre-C13 strike-slip kinematics.

  9. High-speed X-ray microscopy by use of high-resolution zone plates and synchrotron radiation.

    PubMed

    Hou, Qiyue; Wang, Zhili; Gao, Kun; Pan, Zhiyun; Wang, Dajiang; Ge, Xin; Zhang, Kai; Hong, Youli; Zhu, Peiping; Wu, Ziyu

    2012-09-01

    X-ray microscopy based on synchrotron radiation has become a fundamental tool in biology and life sciences to visualize the morphology of a specimen. These studies have particular requirements in terms of radiation damage and the image exposure time, which directly determines the total acquisition speed. To monitor and improve these key parameters, we present a novel X-ray microscopy method using a high-resolution zone plate as the objective and the matching condenser. Numerical simulations based on the scalar wave field theory validate the feasibility of the method and also indicate the performance of X-ray microscopy is optimized most with sub-10-nm-resolution zone plates. The proposed method is compatible with conventional X-ray microscopy techniques, such as computed tomography, and will find wide applications in time-resolved and/or dose-sensitive studies such as living cell imaging. PMID:22763718

  10. Micro-Fresnel-Zone-Plate Array on Flexible Substrate for Large Field-of-View and Focus Scanning

    PubMed Central

    Moghimi, Mohammad J.; Fernandes, Jayer; Kanhere, Aditi; Jiang, Hongrui

    2015-01-01

    Field of view and accommodative focus are two fundamental attributes of many imaging systems, ranging from human eyes to microscopes. Here, we present arrays of Fresnel zone plates fabricated on a flexible substrate, which allows for the adjustment of both the field of view and optical focus. Such zone plates function as compact and lightweight microlenses and are fabricated using silicon nanowires. Inspired by compound eyes in nature, these microlenses are designed to point along various angles in order to capture images, offering an exceptionally wide field of view. Moreover, by flexing the substrate, the lens position can be adjusted, thus achieving axial focus scanning. An array of microlenses on a flexible substrate was incorporated into an optical system to demonstrate high resolution imaging of objects located at different axial and angular positions. These silicon based microlenses could be integrated with electronics and have a wide range of potential applications, from medical imaging to surveillance. PMID:26515117

  11. APD-based X-ray imaging telescope using fresnel zone plates for extremely high Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Squillante, Michael R.; Myers, Richard A.; Woodring, Mitchell; Christian, James F.; Robertson, Frank; Farrell, Richard; Kogan, Alexander I.; Tiernan, Timothy C.; Entine, Gerald

    2005-09-01

    A method for constructing an x-ray telescope with exceedingly hgh spatial resolution is to use a pair of coaxial, Fresnel zone plates aligned with an imaging x-ray detector. This combination allows the high sensitivity imaging of x-ray and gamma-ray sources ranging in energy from 1 keV to several hundred keV over a field of view of several degrees with spatial resolution of a fraction of an arc minute. We have implemented a version of such a telescope using several relatively new technologies. These include specialized techniques for constructing Fresnel zone plates from thin sheets of tungsten, a 64-element, avalanche photodiode (APD) array coupled to a matching, segmented, CsI(T1) scintillator, a new ASIC which provides 16-channels of low noise amplification, and image processing software that provides the user not only with localized intensity information, but also with localized spectral information.

  12. Beam size measurement of the stored electron beam at the APS storage ring using zone plate optics and undulator radiation

    SciTech Connect

    Cai, Z.; Lai, B.; Yun, W.

    1997-10-01

    Beam sizes of the stored electron beam at the Advanced Photon Source storage ring were measured using zone-plate optics and undulator radiation. A gold Fresnel zone plate (3.5 {micro}m thick) located 33.9 meters from the x-ray source focused radiation of 18 keV, selected by a cryogenically cooled Si(111) crystal in horizontal deflection, and formed a source image in a transverse plane 2.41 m downstream. The sizes of the source image were determined from measured intensity profiles of x-ray fluorescence from a smooth nickel edge (1.5 {micro}m thick), fabricated using a lithographic technique, while the nickel edge was scanned across over the beam in the transverse plane. The measured vertical and horizontal sizes of the electron beam were 60 {+-} 4.3 {micro}m and 300 {+-} 13 {micro}m, respectively, in reasonable agreement with the expected values.

  13. Preliminary Investigation to Resolve the Shear Velocity Structure of the Mantle Transition Zone beneath the Caroline Plate, Equatorial Western Pacific

    NASA Astrophysics Data System (ADS)

    Konishi, K.; Kawai, K.; Fuji, N.; Lee, S.; Geller, R. J.

    2013-12-01

    The Mantle Transition Zone (MTZ), which lies in the depth range from 410-660 km, is considered to be a region capable of carrying a large amount of water and other volatiles. A unique feature of the MTZ beneath the northwest Pacific rim is the stagnant slab which lies below much of the West Philippine Basin and extends laterally over a distance of thousands of kilometers beneath Korea and northeast China. In recent years, suggestions have been made that explain the seismicity and intra-plate volcanism in this region in terms of hydrous magmatic plumes rising from the MTZ. However, the exact mechanism remains under debate. An equally important, but less well-known, observation is that a stagnant slab appears to exist beneath much of the Caroline Plate in the equatorial western Pacific as well. If a stagnant slab does exist here, it is most likely a result of the long northward migration of the Australian Plate and subduction since its breakaway from the Antarctic. However, due to tectonic complexity and the lack of seismic stations, the structure and properties of the stagnant slab and the MTZ beneath the Caroline plate are not well understood. Also it is unclear if the large volcanic outflows around the Caroline Plate such as the Eurpik Rise can be explained by a hydrous magmatic plume stemming from the MTZ. To understand the shear-wave velocity structure of the MTZ beneath the Caroline Plate, we employ a body wave waveform inversion technique. Fuji et al. (PEPI, 2010) conducted body wave waveform inversion for the mantle transition zone beneath Japan. In this study we present preliminary results for an application of their methods to infer upper mantle and MTZ structure beneath the Caroline plate. We also estimate the resolving power of full-waveform inversion for a dataset obtained from the IRIS (Incorporated Research Institutions for Seismology) network for shear velocity structure in the upper mantle, especially for the mantle transition zone beneath the

  14. Tectono-stratigraphic signature of a rapid multistage subsiding rift basin in the Tyrrhenian-Apennine hinge zone (Italy): A possible interaction of upper plate with subducting slab

    NASA Astrophysics Data System (ADS)

    Milia, Alfonsa; Torrente, Maurizio M.

    2015-05-01

    The Campania Plain is a rapidly subsiding Quaternary basin that formed on the eastern margin of the Tyrrhenian Sea in association with the younger phase of Tyrrhenian rifting. It is located in the hinge area between the Apennines fold-thrust belt and the Tyrrhenian extensional backarc basin. By combining original stratigraphic analyses of well logs and seismic profiles we built a basin subsidence curve, mapped the fault pattern of the Campania Plain and analyzed the impact of the block faulting on the sedimentology and stratigraphic architecture of the basin fill. Well data indicate that the Quaternary succession consists of offshore, shoreface and coal-bearing coastal plain deposits arranged to form thick aggradational and retrogradational units. The sequence stratigraphy interpretation of well logs permitted us to recognize thirteen depositional sequences and the stratigraphic signatures of the rift stages. The study area corresponds to a sediment overfilled/balanced infill basin type that resulted from superposition of several rifting events characterized by high rates of basin subsidence. Taking into account the geological data of the adjacent areas, we propose a Pliocene-Quaternary rifting evolution of the upper Tyrrhenian plate consisting of four episodes. Two peculiar features of the Tyrrhenian rifting are a skip of the extensional axial zone eastwards leaving the previous zone of high strain localization (Vavilov basin), followed by a dramatic change (90°) of the direction of extension. Because these Tyrrhenian features cannot be accounted for by the current rifting models we hypothesized a link between the evolution of upper plate and subducting slab. The proposed geodynamic scenario is characterized by a progressive rupture of the subducting plate and formation of extensional basins in the upper plate.

  15. Programmable phase plate for tool modification in laser machining applications

    DOEpatents

    Thompson Jr., Charles A.; Kartz, Michael W.; Brase, James M.; Pennington, Deanna; Perry, Michael D.

    2004-04-06

    A system for laser machining includes a laser source for propagating a laser beam toward a target location, and a spatial light modulator having individual controllable elements capable of modifying a phase profile of the laser beam to produce a corresponding irradiance pattern on the target location. The system also includes a controller operably connected to the spatial light modulator for controlling the individual controllable elements. By controlling the individual controllable elements, the phase profile of the laser beam may be modified into a desired phase profile so as to produce a corresponding desired irradiance pattern on the target location capable of performing a machining operation on the target location.

  16. Physics-Based 3-D Simulation for Earthquake Generation Cycles at Plate Interfaces in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Hashimoto, Chihiro; Fukuyama, Eiichi; Matsu'ura, Mitsuhiro

    2014-08-01

    The generation of interplate earthquakes can be regarded as a process of tectonic stress accumulation and release, driven by relative plate motion. We completed a physics-based simulation system for earthquake generation cycles at plate interfaces in the Japan region, where the Pacific plate is descending beneath the North American and Philippine Sea plates, and the Philippine Sea plate is descending beneath the North American and Eurasian plates. The system is composed of a quasi-static tectonic loading model and a dynamic rupture propagation model, developed on a realistic 3-D plate interface model. The driving force of the system is relative plate motion. In the quasi-static tectonic loading model, mechanical interaction at plate interfaces is rationally represented by the increase of tangential displacement discontinuity (fault slip) across them on the basis of dislocation theory for an elastic surface layer overlying Maxwell-type viscoelastic half-space. In the dynamic rupture propagation model, stress changes due to fault slip motion on non-planar plate interfaces are evaluated with the boundary integral equation method. The progress of seismic (dynamic) or aseismic (quasi-static) fault slip on plate interfaces is governed by a slip- and time-dependent fault constitutive law. As an example, we numerically simulated earthquake generation cycles at the source region of the 1968 Tokachi-oki earthquake on the North American-Pacific plate interface. From the numerical simulation, we can see that postseismic stress relaxation in the asthenosphere accelerates stress accumulation in the source region. When the stress state of the source region is close to a critical level, dynamic rupture is rapidly accelerated and develops over the whole source region. When the stress state is much lower than the critical level, the rupture is not accelerated. This means that the stress state realized by interseismic tectonic loading essentially controls the subsequent dynamic

  17. Plate boundary forces in the vicinity of Trinidad-the-transition from transpression to transtension in the Southern Caribbean plate boundary zones

    SciTech Connect

    Algar, S.T.; Pindell, J.L. )

    1993-02-01

    Deformation in the southern Caribbean plate boundary zones as recorded in the Northern Range of Trinidad initiated in the Oligocene with northward vergent gravity sliding of Northern Range sediments due to uplift and oversteepening of the previously passive margin by the eastward migration of the Caribbean flexural forebulge. Progressive east-southeast transvergence of the Caribbean Plate with respect to South America overthrust incorporated the Northern Range sediments into the Caribbean accretionary prism, thrusting them south-southeast to produce a Middle Miocene transpressive foreland fold and thrust belt in southern Trinidad. Late Miocene deformation within Trinidad was increasingly dominated by right-lateral strike-slop (RLSS) faulting, at the expense of transpressive compressional features. Right-stepping of RLSS motion initiated the Gulf of Paria and Caroni pull-apart basins, Since Early Pliocene these basins and other areas to the north of Trinidad have undergone north-south extension in addition to east-west trending RLSS. Such extension caused the northward withdrawal of Caribbean terranes from atop of the Northern Range, Resulting in rapid isostatically induced uplift (approximately 0.5 mmyr[sup -1]). This change in deformation style may relate to a hitherto unrecognized shift in the relative motion of the eastern Caribbean Plate with respect to South America: from east-southeast-directed transpression to east-northeast-directed transtension.

  18. Plate boundary and major fault system in the overriding plate within the Shumagin gap at the Alaska-Aleutian subduction zone

    NASA Astrophysics Data System (ADS)

    Becel, A.; Shillington, D. J.; Nedimovic, M. R.; Keranen, K. M.; Li, J.; Webb, S. C.; Kuehn, H.

    2013-12-01

    Structure in the overriding plate is one of the parameters that may increase the tsunamigenic potential of a subduction zone but also influence the seismogenic behavior and segmentation of great earthquake rupture. The Alaska-Aleutian margin is characterized by along-strike changes in plate interface coupling over relatively small distances. Here, we present trench normal multichannel seismic (MCS) profiles acquired across the Shumagin gap that has not broken in many decades and appears to be weakly coupled. The high fold, deep penetration (636 channel, 8-km long streamer, 6600 cu.in airgun source) MCS data were acquired as part of the ALEUT project. This dataset gives us critical new constraints on the interplate boundary that can be traced over ~100 km distance beneath the forearc with high variation in its reflection response with depth. These profiles also reveal the detailed upper plate fault structure and forearc morphology. Clear reflections in the overriding plate appear to delineate one or more large faults that cross the shelf and the upper slope. These faults are observed 75 km back from the trench and seem to branch at depth and connect to the plate interface within this gap at ~11 s twtt. We compare the reflective structure of these faults to that of the plate boundary and examine where it intersects the megathrust with respect of the expected downdip limit of coupling. We also compare this major structure with the seismicity recorded in this sector. The imaged fault system is associated with a large deep basin (~6s twt) that is an inherited structure formed during the pre-Aleutian period. Basins faults appear to have accommodated primarily normal motion, although folding of sediments near the fault and complicated fault geometries in the shallow section may indicate that this fault has accommodated other types of motion during its history that may reflect the stress-state at the megathrust over time. The deformation within the youngest sediment also

  19. Detailed structures of the subducted Philippine Sea Plate beneath northeast Taiwan: A new type of double seismic zone

    NASA Astrophysics Data System (ADS)

    Kao, Honn; Rau, Ruey-Juin

    1999-01-01

    We studied the detailed structure of the subducted Philippine Sea plate beneath northeast Taiwan where oblique subduction, regional collision, and back arc opening are all actively occurring. Simultaneous inversion for velocity structure and earthquake hypocenters are performed using the vast, high-quality data recorded by the Taiwan Seismic Network. We further supplement the inversion results with earthquake source parameters determined from inversion of teleseismic P and SH waveforms, a critical step to define the position of plate interface and the state of strain within the subducted slab. The most interesting feature is that relocated hypocenters tend to occur along a two-layered structure. The upper layer is located immediately below the plate interface and extends down to 70-80 km at a dip of 40°-50°. Below approximately 100 km, the dip increases dramatically to 70°-80°. The lower layer commences at 45-50 km and stays approximately parallel to the upper layer with a separation of 15±5 km in between down to 70-80 km. Below that the separation decreases and the two layers seem to gradually merge into one Wadati-Benioff Zone. We propose to term the classic double seismic zones observed beneath Japan and Kuril as "type I" and that we observed as "type II," respectively. A global survey indicates that type II double seismic zones are also observed in New Zealand near the southernmost North Island, Cascadia, just north of the Mendocino triple junction, and the Cook Inlet area of Alaska. All of them are located near the termini of subducted slabs in a tectonic setting of oblique subduction. We interpret the seismogenesis of type II double seismic zones as reflecting the lateral compressive stress between the subducted plate and the adjacent lithosphere (originating from oblique subduction) and the downdip extension (from slab pulling force). The upper seismic layer represents seismicity occurring in the upper crust of a subducted plate and/or along the plate

  20. Fabrication of large aperture kinoform phase plates in fused silica for smoothing focal plane intensity profiles

    SciTech Connect

    Rushford, M.; Dixit, S.; Thomas, I.; Perry, M.

    1996-04-26

    We have fabricated large aperture (40-cm) kinoform phase plates for producing super-Gaussian focal plane intensity profiles. The continuous phase screen, designed using a new iterative procedure, was fabricated in fused silica as a 16-level, one-wave deep rewrapped phase profile using a lithographic process and wet etching in buffered hydrofluoric acid. The observed far-field contains 94% of the incident energy inside the desired spot.

  1. Western Renewable Energy Zones, Phase 1: QRA Identification Technical Report

    SciTech Connect

    Pletka, R.; Finn, J.

    2009-10-01

    This report describes the Western Renewable Energy Zones (WREZ) Initiative Phase 1 Qualified Resource Area identification process, including the identification and economic analysis of Qualified Resource Areas (QRAs) and 'non-REZ' resources. These data and analyses will assist the Western US in its renewable energy transmission planning goals. The economic analysis in this report produced the input data for the WREZ Generation and Transmission model, which is a screening-level model to determine the optimal routing for and cost of delivering renewable energy from QRAs to load centers throughout the Western Interconnection. In June 2009, the Western Governors' Association accepted the Western Governors' Association WREZ Phase 1 Report in which the QRAs were mapped and the entire WREZ Phase 1 process was explained in general. That same month the Lawrence Berkeley National Laboratory released the WREZ Generation and Transmission Model (GTM), which was also developed by Black & Veatch. This report details the assumptions and methodologies that were used to produce the maps and resource analyses in the WGA report as well as the economic data used by the WREZ GTM. This report also provides the results of the non-REZ resource analysis for the first time in the WREZ initiative.

  2. A wide-angle seismic survey of the Hecataeus Ridge, south of Cyprus: a microcontinental block from the African plate docked in a subduction zone?

    NASA Astrophysics Data System (ADS)

    Rahimi, Ayda; Welford, Kim; Hall, Jeremy; Hübscher, Christian; Louden, Keith; Ehrhardt, Axel

    2013-04-01

    Cyprus lies at the southern edge of the Aegean-Anatolian microplate, caught in the convergence of Africa and Eurasia. Subduction of the African plate below Cyprus has probably ceased and this has been attributed to the docking in the subduction zone of the Eratosthenes Seamount microcontinental fragment on the northern edge of the African plate. In early 2010, on R.V. Maria S. Merian, we conducted a wide-angle seismic survey to test the hypothesis that the Hecataeus Ridge, another possible microcontinental block lying immediately offshore SE Cyprus, might be related to an earlier docking event. The upper crust of southern Cyprus is dominated by ophiolites, with seismic velocities of up to 7 km s-1. A wide angle seismic profile along Hecataeus Ridge was populated with 15 Canadian and German ocean-bottom seismographs at 5 km intervals and these recorded shots from a 6000 cu. in. air gun array, fired approximately every 100 m. Rough topography of the seabed has made picking of phases and their modelling a demanding task. Bandpass and coherency filtering have enabled us to pick phases out to around 80 km. Tomographic inversion of short-range first arrivals provided an initial model of the shallow sub-seabed structure. Forward modelling by ray-tracing, using the code of Zelt and Smith, was then used to model crustal structure down to depths of around 20 km, with occasional evidence of reflections from deeper boundaries (Moho?). Modelling results provide good control on P-wave velocities in the top 20 km and some indications of deeper events. There is no evidence of true velocities approaching 7 km/s in the top 20 km below the Ridge that might indicate the presence of ophiolitic rocks. Regional gravity and magnetic field data tend to support this proposition. We thus conclude that Hecataeus Ridge is not composed of characteristically ophiolitic, Cyprus (upper plate) crust, and it might well be derived from the African (lower) plate.

  3. Measurement of displacement using phase shifted wedge plate lateral shearing interferometry

    NASA Astrophysics Data System (ADS)

    Disawal, Reena; Prakash, Shashi

    2016-03-01

    In present communication, a simple technique for measurement of displacement using phase shifted wedge plate lateral shearing interferometry is described. The light beam from laser is expanded and illuminates a wedge plate of relatively large angle. Light transmitted through the wedge plate is converged onto a reflecting specimen using a focusing lens. Back-reflected wavefront from the specimen is incident on the wedge plate. Because of the tilt and shear of the wavefront reflected from the wedge plate, typical straight line fringes appear. These fringes are superimposed onto a sinusoidal grating forming a moiré pattern. The orientation of the moiré fringes is a function of specimen displacement. Four step phase shifting test procedure has been incorporated by translating the grating in phase steps of π/2. Necessary mathematical formulation to establish correlation between the 'difference phase' and the displacement of the specimen surface is undertaken. The technique is automatic and provides resolution and expanded uncertainty of 1 μm and 0.246 μm, respectively. Detailed uncertainty analysis is also reported.

  4. Neotectonics of the Owen Fracture Zone (NW Indian Ocean): Structural evolution of an oceanic strike-slip plate boundary

    NASA Astrophysics Data System (ADS)

    Rodriguez, M.; Fournier, M.; Chamot-Rooke, N.; Huchon, P.; Bourget, J.; Sorbier, M.; Zaragosi, S.; Rabaute, A.

    2011-12-01

    The Owen Fracture Zone is a 800 km-long fault system that accommodates the dextral strike-slip motion between India and Arabia plates. Because of slow pelagic sedimentation rates that preserve the seafloor expression of the fault since the Early Pliocene, the fault is clearly observed on bathymetric data. It is made up of a series of fault segments separated by releasing and restraining bends, including a major pull-apart basin at latitude 20°N. Some distal turbiditic channels from the Indus deep-sea fan overlap the fault system and are disturbed by its activity, thus providing landmarks to date successive stages of fault activity and structural evolution of the Owen Fracture Zone from Pliocene to Present. We determine the durability of relay structures and the timing of their evolution along the principal displacement zone, from their inception to their extinction. We observe subsidence migration in the 20°N basin, and alternate activation of fault splays in the vicinity of the Qalhat seamount. The present-day Owen Fracture Zone is the latest stage of structural evolution of the 20-Myr-old strike-slip fault system buried under Indus turbiditic deposits whose activity started at the eastern foot of the Owen Ridge when the Gulf of Aden opened. The evolution of the Owen Fracture Zone since 3-6 Myr reflects a steady state plate motion between Arabia and India, such as inferred by kinematics for the last 20 Myr period. The structural evolution of the Owen Fracture Zone since 20 Myr, including fault segments propagation and migration, pull-apart basin opening and extinction, seems to be characterized by a progressive reorganization of the fault system, and does not require any major kinematics change.

  5. Comment on Sub-15 nm Hard X-Ray Focusing with a New Total-Reflection Zone Plate

    SciTech Connect

    Specht, Eliot D

    2011-01-01

    Takano et al. report the focusing of 10-keV X-rays to a size of 14.4 nm using a total-reflection zone plate (TRZP). This focal size is at the diffraction limit for the optic's aperture. This would be a noteworthy result, since the TRZP was fabricated using conventional lithography techniques. Alternative nanofocusing optics require more demanding fabrication methods. However, as I will discuss in this Comment, the intensity distribution presented by Takano et al. (Fig. 4 of ref. 1) is more consistent with the random speckle pattern produced by the scattering of a coherent incident beam by a distorted optic than with a diffraction-limited focus. When interpreted in this manner, the true focal spot size is {approx}70 nm: 5 times the diffraction limit. When a coherent photon beam illuminates an optic containing randomly distributed regions which introduce different phase shifts, the scattered diffraction pattern consists of a speckle pattern. Each speckle will be diffraction-limited: the peak width of a single speckle depends entirely on the source coherence and gives no information about the optic. The envelope of the speckle distribution corresponds to the focal spot which would be observed using incoherent illumination. The width of this envelope is due to the finite size of the coherently-diffracting domains produced by slope and position errors in the optic. The focal intensity distribution in Fig. 4 of ref. 1 indeed contains a diffraction-limited peak, but this peak contains only a fraction of the power in the focused, and forms part of a distribution of sharp peaks with an envelope {approx}70 nm in width, just as expected for a speckle pattern. At the 4mm focal distance, the 70 nm width corresponds to a slope error of 18 {micro}rad. To reach the 14 nm diffraction limit, the slope error must be reduced to 3 {micro}rad. Takano et al. have identified a likely source of this error: warping due to stress as a result of zone deposition. It will be interesting to see

  6. Identification of subducting plate structure within seismogenic zones and relationships with seismicity

    NASA Astrophysics Data System (ADS)

    Bassett, D.; Watts, A. B.

    2014-12-01

    The roughness of subducting plates is one of the most important parameters controlling the seismogenic behavior of subduction megathrusts, but in most regions the distribution of subducting relief is inferred from structure seaward of trenches. Spectral averaging techniques developed to remove the steep topographic gradients across forearcs are shown to improve resolution of local trench-slope uplift, that may be diagnostic of subducting relief. This interpretation is locally calibrated where the Louisville Ridge subducts at the Tonga trench. From a global extension of these techniques, >200 residual bathymetric anomalies are identified, enabling links between subducting relief, slip behavior and seismicity to be reconsidered. We interpret >150 potential subducting seamounts, 36 of which have height ≥1 km and area ≥500 km2. These anomalies are similar in wavelength, amplitude and morphology with unsubducted seamounts, are associated with aseismic regions in Tonga and Mariana, and prevented along strike rupture propagation in large recent earthquakes in Java (2006) and Japan (2011). Subducting aseismic ridges in Peru, Ecuador and Costa-Rica are associated with uplift and steepening of the outer-forearc and a local increase in the width and elevation of the volcanic-arc. Associations with complex large earthquakes, higher frequencies of small events, and creep suggest aseismic ridges may also subduct via the development and evolution of an adjacent fracture network. Megathrust complexity is expected to be greatest on subducting ridge flanks. The bathymetric expression of subducting relief is strongest near the trench (<70 km) and above shallow slab depths (<~17 km). Dip-parallel transitions in the surface expression of aseismic ridges may reflect physical transitions in megathrust slip-behavior and/or material properties in the overthrusting wedge. Aseismic ridges and seamounts represent seafloor roughness over different wavelengths and are associated with

  7. Variation of seismic coupling with slab detachment and upper plate structure along the western Hellenic subduction zone

    NASA Astrophysics Data System (ADS)

    Laigle, Mireille; Sachpazi, Maria; Hirn, Alfred

    2004-10-01

    The western Hellenic subduction zone is characterized by a trenchward velocity of the upper plate. In the Ionian islands segment, complete seismic coupling is achieved, as is predicted by standard plate-tectonic models in which there is no slab pull force because the slab has broken off. The moderate local seismic moment rate relates to a shallow downdip limit for the seismogenic interface. This characteristic may be attributed to the ductility of the lower crust of the upper plate, which allows a décollement between the upper crust of the overriding plate and the subducting plate. Farther south, a deeper downdip limit of the seismogenic interface is indicated by thrust-faulting earthquakes, which persist much deeper in western Crete. A correspondingly larger downdip width of this seismogenic zone is consistent with the suggested larger maximum magnitude of earthquakes here. However, since the seismic moment release rate seems to be moderate in the Peloponnese and western Crete, like in in the Ionian islands, this seismically active interface cannot maintain complete seismic coupling across its larger downdip width. A cause may be the lateral addition of overweight to the part of the slab still attached in Crete, by the free fall of its part that has broken off from the surface further north. This increased slab pull reduces the compressive normal stress across the seismogenic interface and thus causes partial seismic coupling in its shallower part. However, the width of this part may provide an additional area contributing to slip in large earthquakes, which may nucleate deeper on stick-slip parts of the interface. Hints at anomalies in structure and seismicity, which need to be resolved, may relate to the present location of the edge of the tear in the slab.

  8. Along-Strike Electrical Conductivity Variations in the Incoming Plate and Shallow Forearc of the Cascadia Subduction Zone

    NASA Astrophysics Data System (ADS)

    Key, K.; Bedrosian, P.; Egbert, G. D.; Livelybrooks, D.; Parris, B. A.; Schultz, A.

    2015-12-01

    The Magnetotelluric Observations of Cascadia using a Huge Array (MOCHA) experiment was carried out to study the nature of the seismogenic locked zone and the down-dip transition zone where episodic tremor and slip (ETS) originates. This amphibious magnetotelluric (MT) data set consists of 8 offshore and 15 onshore profiles crossing from just seaward of the trench to the western front of the Cascades, with a north-south extent spanning from central Oregon to central Washington. The 71 offshore stations and the 75 onshore stations (red triangles in the image below) fit into the broader context of the more sparsely sampled EarthScope MT transportable array (black triangles) and other previous and pending MT surveys (other symbols). These data allows us to image variations in electrical conductivity along distinct segments of the Cascadia subduction zone defined by ETS recurrence intervals. Since bulk conductivity in this setting depends primarily on porosity, fluid content and temperature, the conductivity images created from the MOCHA data offer unique insights on fluid processes in the crust and mantle, and how the distribution of fluid along the plate interface relates to observed variations in ETS behavior. This abstract explores the across- and along-strike variations in the incoming plate and the shallow offshore forearc. In particular we examine how conductivity variations, and the inferred fluid content and porosity variations, are related to tectonic segmentation, seismicity and deformation patterns, and arc magma variations along-strike. Porosity inferred in the forearc crust can be interpreted in conjunction with active and passive seismic imaging results and may provide new insights on the origin of recently observed extremely high heat flow values. A companion abstract (Parris et al.) examines the deeper conductivity structure of the locked and ETS zones along the plate interface in order to identify correlations between ETS occurrence rates and inferred

  9. Volta phase plate cryo-EM of the small protein complex Prx3.

    PubMed

    Khoshouei, Maryam; Radjainia, Mazdak; Phillips, Amy J; Gerrard, Juliet A; Mitra, Alok K; Plitzko, Jürgen M; Baumeister, Wolfgang; Danev, Radostin

    2016-01-01

    Cryo-EM of large, macromolecular assemblies has seen a significant increase in the numbers of high-resolution structures since the arrival of direct electron detectors. However, sub-nanometre resolution cryo-EM structures are rare compared with crystal structure depositions, particularly for relatively small particles (<400 kDa). Here we demonstrate the benefits of Volta phase plates for single-particle analysis by time-efficient cryo-EM structure determination of 257 kDa human peroxiredoxin-3 dodecamers at 4.4 Å resolution. The Volta phase plate improves the applicability of cryo-EM for small molecules and accelerates structure determination. PMID:26817416

  10. Volta phase plate cryo-EM of the small protein complex Prx3

    NASA Astrophysics Data System (ADS)

    Khoshouei, Maryam; Radjainia, Mazdak; Phillips, Amy J.; Gerrard, Juliet A.; Mitra, Alok K.; Plitzko, Jürgen M.; Baumeister, Wolfgang; Danev, Radostin

    2016-01-01

    Cryo-EM of large, macromolecular assemblies has seen a significant increase in the numbers of high-resolution structures since the arrival of direct electron detectors. However, sub-nanometre resolution cryo-EM structures are rare compared with crystal structure depositions, particularly for relatively small particles (<400 kDa). Here we demonstrate the benefits of Volta phase plates for single-particle analysis by time-efficient cryo-EM structure determination of 257 kDa human peroxiredoxin-3 dodecamers at 4.4 Å resolution. The Volta phase plate improves the applicability of cryo-EM for small molecules and accelerates structure determination.

  11. Phase Velocity Method for Guided Wave Measurements in Composite Plates

    NASA Astrophysics Data System (ADS)

    Moreno, E.; Galarza, N.; Rubio, B.; Otero, J. A.

    Carbon Fiber Reinforced Polymer is a well-recognized material for aeronautic applications. Its plane structure has been widely used where anisotropic characteristics should be evaluated with flaw detection. A phase velocity method of ultrasonic guided waves based on a pitch-catch configuration is presented for this purpose. Both shear vertical (SV) and shear horizontal (SH) have been studied. For SV (Lamb waves) the measurements were done at different frequencies in order to evaluate the geometrical dispersion and elastic constants. The results for SV are discussed with an orthotropic elastic model. Finally experiments with lamination flaws are presented.

  12. Kinematics to dynamics in the New Zealand Plate boundary zone: implications for the strength of the lithosphere

    NASA Astrophysics Data System (ADS)

    Lamb, Simon

    2015-05-01

    New Zealand straddles the boundary between the Australian and Pacific Plate. Cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation in a zone of continental lithosphere up to 250 km wide. I investigate the implications of the short-term kinematics for the strength of the deforming lithosphere. I use a compilation of seismic reflection/refraction studies and high quality receiver function analyses to determine both the regional structure of the crust, which ranges from 20 to 50 km thick, and fields of buoyancy stress (or GPE per unit volume). Deformation over thousands of years is quantified in terms of velocity and strain rate fields, based on an inversion of neotectonic fault slip and palaeomagnetic data, in the context of the short-term relative plate motions. Forces on the subduction megathrust, as well as deviatoric stresses in the behind subduction region, are calculated from simple 2-D force balances across the Hikurangi Margin, given negligible deviatoric stresses at the along-strike transition between backarc extension and compression. Average megathrust shear stresses are in the range 6-15 MPa, and average lithospheric stresses <20 MPa in the overriding plate. The regional lithospheric strength of the plate boundary zone, assuming a viscous rheology (Newtonian or power law), is determined from an inversion of the field of gradients of buoyancy stress (averaged over either the top 25 km of the crust, or 100-km-thick lithosphere) and strain rate, using the thin sheet stress balance equations, calibrated with the subduction force balance analysis. Effective viscosities for the deforming lithosphere and/or crust are in the range 0.1-5 × 1021 Pa s, with marked weakening in zones of high strain rate, and an abrupt transition to viscosities >1022 Pa s at the margins of the rigid plates. If lateral variations in effective viscosity are only due to non-Newtonian behaviour, these data indicate a bulk power law rheology, with

  13. Radiocarbon evidence for extensive plate-boundary rupture about 300 years ago at the Cascadia subduction zone

    USGS Publications Warehouse

    Nelson, A.R.; Atwater, B.F.; Bobrowsky, P.T.; Bradley, L.-A.; Clague, J.J.; Carver, G.A.; Darienzo, M.E.; Grant, W.C.; Krueger, H.W.; Sparks, R.; Stafford, Thomas W., Jr.; Stuiver, M.

    1995-01-01

    THE Cascadia subduction zone, a region of converging tectonic plates along the Pacific coast of North America, has a geological history of very large plate-boundary earthquakes1,2, but no such earthquakes have struck this region since Euro-American settlement about 150 years ago. Geophysical estimates of the moment magnitudes (Mw) of the largest such earthquakes range from 8 (ref. 3).to 91/2 (ref. 4). Radiocarbon dating of earthquake-killed vegetation can set upper bounds on earthquake size by constraining the length of plate boundary that ruptured in individual earthquakes. Such dating has shown that the most recent rupture, or series of ruptures, extended at least 55 km along the Washington coast within a period of a few decades about 300 years ago5. Here we report 85 new 14C ages, which suggest that this most recent rupture (or series) extended at least 900 km between southern British Columbia and northern California. By comparing the 14C ages with written records of the past 150 years, we conclude that a single magnitude 9 earthquake, or a series of lesser earthquakes, ruptured most of the length of the Cascadia subduction zone between the late 1600s and early 1800s, and probably in the early 1700s.

  14. Broadband polarization gratings for efficient liquid crystal display, beam steering, spectropolarimetry, and Fresnel zone plate

    NASA Astrophysics Data System (ADS)

    Oh, Chulwoo

    displays is the polymer-PG display, which allows an immediate brightness improvement (up to a factor of two) of conventional LC displays by replacing absorbing polarizers with achromatic PGs as thin, transmissive polymer films. We demonstrate the first proof-of-concept prototype projector based on the polymer-PG display and we also discuss optical design considerations and challenges toward a viable solution for our ultrabright pico-projector applications of the polymer-PG display. Second, two novel beam steering concepts based on the PG diffraction have been proposed. The polarization-sensitive diffraction of the PGs provides very attractive beam steering operations with ultra-high efficiency over wide steering angles by all-thin-plate electro-optical systems. We developed a non-mechanical, wide-angle beam steering system using stacked PGs and LC waveplates, and we also demonstrated a continuous beam steering using two rotating PGs, named the Risley grating as a thin-plate version of the Risley prism. The third PG application is in imaging and non-imaging spectropolarimetry. We have shown a snapshot, hyperspectral, full-Stokes polarimeter using inline PGs and quarter-waveplates. The use of PGs as a new polarimetric element for astronomical instruments in the mid-wave IR wavelengths also has been proposed to overcome current limitations of existing IR polarimeters. In the last part of this Dissertation, we introduce a polarization-type Fresnel zone plates (P-FZPs), comprising of spatially distributed linear birefringence or concentric PG (CPG) patterns. Effective fabrication methods of P-FZPs have been developed using polarization holography based on the Michelson interferometer and photoalignment of LC materials. We demonstrated high-quality P-FZPs, which exhibit ideal Fresnel-type lens effects, formed as both LC polymer films and electro-optical LC devices. We also discuss the polarization-selective lens properties of the P-FZPs as well as their electro-optical switching

  15. Practical factors affecting the performance of a thin-film phase plate for transmission electron microscopy

    PubMed Central

    Danev, Radostin; Glaeser, Robert M.; Nagayama, Kuniaki

    2011-01-01

    A number of practical issues must be addressed when using thin carbon films as quarter-wave plates for Zernike phase-contrast electron microscopy. We describe, for example, how we meet the more stringent requirements that must be satisfied for beam alignment in this imaging mode. In addition we address the concern that one might have regarding the loss of some of the scattered electrons as they pass through such a phase plate. We show that two easily measured parameters, (1) the low-resolution image contrast produced in cryo-EM images of tobacco mosaic virus particles and (2) the fall-off of the envelope function at high resolution, can be used to quantitatively compare the data quality for Zernike phase-contrast images and for defocused bright-field images. We describe how we prepare carbon-film phase plates that are initially free of charging or other effects that degrade image quality. We emphasize, however, that even though the buildup of hydrocarbon contamination can be avoided by heating the phase plates during use, their performance nevertheless deteriorates over the time scale of days to weeks, thus requiring their frequent replacement in order to maintain optimal performance. PMID:19157711

  16. Selective mode multiplexer based on phase plates and Mach-Zehnder interferometer with image inversion function.

    PubMed

    Igarashi, Koji; Souma, Daiki; Takeshima, Koki; Tsuritani, Takehiro

    2015-01-12

    We propose a novel mode multiplexer based on phase plates followed by a Mach-Zehnder interferometer (MZI) with image inversion. After the higher-order modes are selectively converted from fundamental linear-polarized (LP) modes by the phase plates, the converted modes are coupled without fundamental loss using MZI with image inversion, in which the original spatial pattern and inverted pattern of the optical signal are interfered. Our scheme is also applicable to the coupling of degenerated LP modes such as LP(11a) and LP(11b). First, we numerically and experimentally evaluate the performance of the mode converter based on phase plates. The mode converter is suitable as long as the five LP modes such as LP(01), LP(11ab) and LP(21ab) are sustained in a few-mode fiber (FMF), although the crosstalk due to excitation of undesirable modes is unavoidable when the higher-order modes over LP(02) are sustained in FMF. Next, we develop and characterize the proposed mode multiplexers based on phase plates and MZIs with image inversion. The insertion loss is suppressed to around 3 dB for mode multiplexing of LP(11a) and LP(11b). Using a fabricated mode multiplexer for LP(31a) and LP(31b), we measure the bit-error rate performance of single-polarization mode-multiplexed quadrature-phase shift keying optical signals. PMID:25835665

  17. Damage localization in aluminum plate with compact rectangular phased piezoelectric transducer array

    NASA Astrophysics Data System (ADS)

    Liu, Zenghua; Sun, Kunming; Song, Guorong; He, Cunfu; Wu, Bin

    2016-03-01

    In this work, a detection method for the damage in plate-like structure with a compact rectangular phased piezoelectric transducer array of 16 piezoelectric elements was presented. This compact array can not only detect and locate a single defect (through hole) in plate, but also identify multi-defects (through holes and surface defect simulated by an iron pillar glued to the plate). The experiments proved that the compact rectangular phased transducer array could detect the full range of plate structures and implement multiple-defect detection simultaneously. The processing algorithm proposed in this paper contains two parts: signal filtering and damage imaging. The former part was used to remove noise from signals. Continuous wavelet transform was applicable to signal filtering. Continuous wavelet transform can provide a plot of wavelet coefficients and the signal with narrow frequency band can be easily extracted from the plot. The latter part of processing algorithm was to implement damage detection and localization. In order to accurately locate defects and improve the imaging quality, two images were obtained from amplitude and phase information. One image was obtained with the Total Focusing Method (TFM) and another phase image was obtained with the Sign Coherence Factor (SCF). Furthermore, an image compounding technique for compact rectangular phased piezoelectric transducer array was proposed in this paper. With the proposed technique, the compounded image can be obtained by combining TFM image with SCF image, thus greatly improving the resolution and contrast of image.

  18. Effect of metachronal phasing on the pumping efficiency of oscillating plate arrays

    NASA Astrophysics Data System (ADS)

    Larson, Mary; Kiger, Ken T.; Abdelaziz, Khaled; Balaras, Elias

    2014-05-01

    A programmable oscillating plate array was constructed in order to study the detailed hydrodynamics of external pumping by a series of oscillating plates at Reynolds numbers on the order of 10. The array was modeled after the geometry and kinematics found in the nymphal mayfly (Ephemeroptera) Centroptilum triangulifer, and consisted of five plates, each of which could be actuated independently for stroke and pitch. Scaled tests were performed at a Reynolds number, Re = fL {g/2}/ ν = 18, with a single stroke kinematic pattern modeled after the living animal. In mayflies, and in many other oscillating plate systems, an antiplectic metachronal wave is used with a phase delay of approximately 90°, which corresponds to a travelling wave that moves from posterior to anterior with a wavelength of approximately four plates. In order to better understand possible reasons for why the animal system might favor the observed phase lag, ensemble-correlation stereo PIV measurements were made to reconstruct the unsteady three-dimensional phase averaged flow field at a resolution that allowed a uniform and converged estimate of the net pumped flux and the total energy dissipation within and around the vicinity of the gill array. The results indicate that the baseline case offered an optimal spot in the mass flux of fluid pumped through the array per unit energy expended, while also providing a great deal of flexibility in modifying the stroke amplitude without interference effects from adjacent gills.

  19. Rayleigh phase velocities in the upper mantle of the Pacific-North American plate boundary in southern California

    NASA Astrophysics Data System (ADS)

    Escobar, L.; Weeraratne, D. S.; Kohler, M. D.

    2013-05-01

    The Pacific-North America plate boundary, located in Southern California, presents an opportunity to study a unique tectonic process that has been shaping the plate tectonic setting of the western North American and Mexican Pacific margin since the Miocene. This is one of the few locations where the interaction between a migrating oceanic spreading center and a subduction zone can be studied. The rapid subduction of the Farallon plate outpaced the spreading rate of the East Pacific Rise rift system causing it to be subducted beneath southern California and northern Mexico 30 Ma years ago. The details of microplate capture, reorganization, and lithospheric deformation on both the Pacific and North American side of this boundary is not well understood, but may have important implications for fault activity, stresses, and earthquake hazard analysis both onshore and offshore. We use Rayleigh waves recorded by an array of 34 ocean bottom seismometers deployed offshore southern California for a 12 month duration from August 2010 to 2011. Our array recorded teleseismic earthquakes at distances ranging from 30° to 120° with good signal-to-noise ratios for magnitudes Mw ≥ 5.9. The events exhibit good azimuthal distribution and enable us to solve simultaneously for Rayleigh wave phase velocities and azimuthal anisotropy. Fewer events occur at NE back-azimuths due to the lack of seismicity in central North America. We consider seismic periods between 18 - 90 seconds. The inversion technique considers non-great circle path propagation by representing the arriving wave field as two interfering plane waves. This takes advantage of statistical averaging of a large number of paths that travel offshore southern California and northern Mexico allowing for improved resolution and parameterization of lateral seismic velocity variations at lithospheric and sublithospheric depths. We present phase velocity results for periods sampling mantle structure down to 150 km depth along the

  20. Joint research effort on vibrations of twisted plates, phase 1: Final results

    NASA Technical Reports Server (NTRS)

    Kielb, R. E.; Leissa, A. W.; Macbain, J. C.; Carney, K. S.

    1985-01-01

    The complete theoretical and experimental results of the first phase of a joint government/industry/university research study on the vibration characteristics of twisted cantilever plates are given. The study is conducted to generate an experimental data base and to compare many different theoretical methods with each other and with the experimental results. Plates with aspect ratios, thickness ratios, and twist angles representative of current gas turbine engine blading are investigated. The theoretical results are generated by numerous finite element, shell, and beam analysis methods. The experimental results are obtained by precision matching a set of twisted plates and testing them at two laboratories. The second and final phase of the study will concern the effects of rotation.

  1. Germanium x-ray phase plates for the production of circularly polarized x-rays

    SciTech Connect

    Yahnke, C.J.; Srajer, G.; Haeffner, D.R.; Mills, D.M.; Assoufid, L.

    1993-10-01

    The authors have constructed an x-ray phase plate to produce both linearly and circularly polarized x-rays at discrete energies between 20 keV and 88 keV. The plate is a monolithic two-crystal design, constructed from germanium, which increases the resultant degree of circular polarization of the output beam. They have measured the degree of circular polarization at 65 keV to be 90% {+-} 4%, significantly better than that produced by silicon phase plates. This radiation was used to measure the magnetic Compton profile for Fe, which was found to be in good agreement with theory and previous work. The underlying x-ray optics and the characterization of the device between 62 keV and 93 keV at the Cornell High Energy Synchrotron Source are presented.

  2. Constraining physical properties of ultra-low velocity zones using multiple seismic phases

    NASA Astrophysics Data System (ADS)

    Jensen, K. J.; Thorne, M. S.; Rost, S.; Nissen-Meyer, T.

    2010-12-01

    Ultra-low velocity zones (ULVZs) are a prominent feature of the lower mantle and may be related to many lower mantle dynamic processes. Several studies have indicated a possible partial melt origin to ULVZs however chemical reactions between the mantle and outer core cannot be ruled out giving a compositional component to ULVZ makeup. In order to determine the true importance of ULVZs, it is first necessary to determine their physical properties and geographic location. ULVZ physical properties (P- and S-wave velocities, density, thickness, and lateral coverage) are not well constrained due to sparse coverage of seismic phases used to probe the CMB, and extensive modeling tradeoffs. In this study we focus on examining ULVZ structure in the western Pacific region. Although several studies have confirmed the presence of ULVZs in this region, these studies have primarily been conducted using a single seismic phase. Yet, these past studies indicate that multiple seismic phases may interact with the same ULVZ. We seek to further constrain ULVZ physical properties using the seismic phases SPdKS, ScP, and PcP. Our primary focus is on ULVZ structure where at least 2 of these 3 seismic phases pass through the same ULVZ. Our SPdKS data set consists of broadband seismic recordings from 150 deep earthquakes occurring between January 1990 to April 2010 along the west boundary of the Pacific plate, and the east and south boundaries of the Eurasian plate. Our ScP and PcP data sets consist of 785 and 819 events, respectively, occurring between the years 1995 and 2000 recorded at the short period arrays of the International Monitoring System. We constrain ULVZ properties by waveform modeling using two new techniques: (1) We use the axi-symmetric finite difference technique PSVaxi to model broadband SPdKS waveforms, and (2) we use the axi-symmetric spectral-element method (AXISEM) to model high frequency (1 Hz) ScP and PcP waveforms. We determine the acceptable model space for each

  3. Stress triggering of the great Indian Ocean strike-slip earthquakes in a diffuse plate boundary zone

    NASA Astrophysics Data System (ADS)

    Wiseman, Kelly; Bürgmann, Roland

    2012-11-01

    On April 11, 2012, two great magnitude 8+ earthquakes occurred within a two-hour period off the west coast of northern Sumatra, Indonesia, in the broadly distributed India-Australia plate boundary zone. The magnitude 8.6 mainshock holds the distinction of being both the largest instrumentally recorded strike-slip earthquake and the largest earthquake away from a recognized plate boundary fault. The mainshock involved sequential ruptures of multiple fault planes oriented nearly perpendicular to each other. The adjacent 2004 megathrust earthquake statically loaded the northern Wharton Basin oceanic lithosphere on both of the 2012 mainshock fault plane orientations, and greatly enhanced the rate of earthquake activity in the region for a year. Viscoelastic relaxation of the asthenosphere following the 2004 and 2005 megathrust earthquakes continued to positively stress the offshore region, correlating with the locations of later strike-slip earthquakes, including two magnitude 7+ and the 2012 magnitude 8+ earthquakes.

  4. The Cretaceous iron belt of northern Chile: role of oceanic plates, a superplume event, and a major shear zone

    NASA Astrophysics Data System (ADS)

    Oyarzun, Roberto; Oyarzún, Jorge; Ménard, Jean Jacques; Lillo, Javier

    2003-08-01

    The Cretaceous constitutes a turning point in the tectonic, magmatic, and metallogenic history of Chile. The geological evidence indicates that a major change occurred in late Neocomian time when superplume emplacement (Mid-Pacific Superplume) and plate reorganization processes took place in the Pacific. The superplume event resulted in a major ridge-push force resulting in increased coupling between the subducting and overriding plates. This completely changed the tectonic setting of Chile ending the Early Cretaceous extensional period (aborted rifting in the back-arc basin), and increasing stress at a crustal scale. As a consequence, overpressurized dioritic magmas were pushed up mainly along the best possible structural path in northern Chile, i.e., the Atacama Fault Zone, eventually forming a +500-km-long belt of Kiruna-type iron deposits with reserves of ~2,000 Mt (60% Fe), a unique case in Chile's geological history.

  5. Biaxial nematic phase stability and demixing behaviour in monolayers of rod-plate mixtures.

    PubMed

    Martínez-Ratón, Yuri; González-Pinto, Miguel; Velasco, Enrique

    2016-09-21

    We theoretically study the phase behaviour of monolayers of hard rod-plate mixtures using a fundamental-measure density functional in the restricted-orientation (Zwanzig) approximation. Particles can rotate in 3D but their centres of mass are constrained to be on a flat surface. In addition, we consider both species to be subject to an attractive potential proportional to the particle contact area on the surface and with adsorption strengths that depend on the species type. Particles have board-like shape, with sizes chosen using a symmetry criterion: same volume and same aspect ratio κ. Phase diagrams were calculated for κ = 10, 20 and 40 and different values of adsorption strengths. For small adsorption strengths the mixtures exhibit a second-order uniaxial nematic-biaxial nematic transition for molar fraction of rods 0 ≤x≲ 0.9. In the uniaxial nematic phase the particle axes of rods and plates are aligned perpendicular and parallel to the monolayer, respectively. At the transition, the orientational symmetry of the plate axes is broken, and they orient parallel to a director lying on the surface. For large and equal adsorption strengths the mixture demixes at low pressures into a uniaxial nematic phase, rich in plates, and a biaxial nematic phase, rich in rods. The demixing transition is located between two tricritical points. Also, at higher pressures and in the plate-rich part of the phase diagram, the system exhibits a strong first-order uniaxial nematic-biaxial nematic phase transition with a large density coexistence gap. When rod adsorption is considerably large while that of plates is small, the transition to the biaxial nematic phase is always of second order, and its region of stability in the phase diagram considerably widens. At very high pressures the mixture can effectively be identified as a two-dimensional mixture of squares and rectangles which again demixes above a certain critical point. We also studied the relative stability of uniform

  6. On the role of inelastic scattering in phase-plate transmission electron microscopy.

    PubMed

    Hettler, Simon; Wagner, Jochen; Dries, Manuel; Oster, Marco; Wacker, Christian; Schröder, Rasmus R; Gerthsen, Dagmar

    2015-08-01

    The phase contrast of Au nanoparticles on amorphous-carbon films with different thicknesses is analyzed using an electrostatic Zach phase plate in a Zeiss 912 Ω transmission electron microscope with in-column energy filter. Specifically, unfiltered and plasmon-filtered phase-plate transmission electron microscopy (PP TEM) images are compared to gain insight in the role of coherence after inelastic scattering processes. A considerable phase-contrast contribution resulting from a combined elastic-inelastic scattering process is found in plasmon-filtered PP TEM images. The contrast reduction compared to unfiltered images mainly originates from zero-order beam broadening caused by the inelastic scattering process. The effect of the sequence of the elastic and inelastic scattering processes is studied by varying the position of the nanoparticles, which can be either located on top or at the bottom of the amorphous-carbon film with respect to the incident electron beam direction. PMID:25879156

  7. Development of large-field high-resolution hard x-ray imaging microscopy and microtomography with Fresnel zone plate objective

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshio; Takeuchi, Akihisa; Terada, Yasuko; Uesugi, Kentaro; Tamura, Shigeharu

    2013-09-01

    A hard x-ray imaging microscope system of high spatial resolution and large field of view (FOV) has been developed at the beamline 37 XU of SPring-8. By utilizing the 30 m-long experimental station, large magnification can be attained with a large diameter Fresnel zone plate (FZP) objective. Some configurations of microscope systems were tested. In a typical condition, a magnification of 133 and a FOV of 123 μm are attained using a FZP with a diameter of 310 μm and an outermost zone width of 100 nm, and the spatial resolution evaluated by observing resolution test chart is 160 nm in full pitch of periodic object with an exposure time of 1 s. When a FZP with an outermost zone width of 50 nm is used, a spatial resolution better than 100 nm is achieved. Phase-contrast imaging by Zernike's method was also tested, and three dimensional measurement by computer tomography (CT) method was also carried out.

  8. Planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as stationary phase

    NASA Astrophysics Data System (ADS)

    Platonov, I. A.; Platonov, V. I.; Pavelyev, V. S.

    2016-04-01

    The high selectivity of the adsorption layer for low-boiling alkanes is shown, the separation factor (α) couple iso-butane / butane is 1.9 at a column temperature of 50 °C.The paper presents sorption and selective properties of planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as the stationary phase.

  9. Irradiation effects on weld heat-affected zone and plate materials (series 11)

    SciTech Connect

    Nanstad, R.K.; McCabe, D.E.

    1995-10-01

    The purpose of this task is to examine the effects of neutron irradiation on the fracture toughness (ductile and brittle) of the HAZ of welds and of A 302 grade B (A302B) plate materials typical of those used fabricating older RPVs. The initial plate material of emphasis will be A302B steel, not the A302B modified with nickel additions. This decision was made by the NRC following a survey of the materials of construction for RPBs in operating U.S. nuclear plants. Reference 1 was used for the preliminary survey, and the information from that report was revised by NRC staff based on information contained in the licensee responses to Generic Letter (GL) 92-01, {open_quotes}Reactor Vessel Structural Integrity, 10CFR50.54(f).{close_quotes} The resulting survey showed a total of eight RPVs with A302B, ten with A302B (modified), and one with A302 grade A plate. Table 5.1 in the previous semiannual report provides a summary of that survey. For the HAZ portion of the program, the intent is to examine HAZ material in the A302B (i.e., with low nickel content) and in A302B (modified) or A533B-1 (i.e., with medium nickel content). During this reporting period, two specific plates were identified as being applicable to this task. One plate is A302B and the other is A302B (modified). The A302B plate (43 x 42 x 7 in.) will be prepared for welding, while the A302B (modified) plate already contains a commercially produced weld (heat 33A277, Linde 0091 flux). These plates were identified from a list of ten materials provided by Mr. E. Biemiller of Yankee Atomic Electric Company (YAEC). The materials have been requested from YAEC for use in this irradiation task, and arrangements are being made with YAEC for procurement of the plates mentioned above.

  10. Preliminary design of a zone plate based hard X-ray monochromatic diffraction nanoprobe for materials studies at APS

    NASA Astrophysics Data System (ADS)

    Cai, Zhonghou; Liu, Wenjun; Tischler, Jonathan Z.; Shu, Deming; Xu, Ruqing; Schmidt, Oliver

    2013-09-01

    Aiming at studies of the micro/nano-structures of a broad range materials and electronic devices, Advance Photon Source (APS) is developing a dedicated diffraction nanoprobe (DNP) beamline for the needs arising from a multidiscipline research community. As a part of the APS Upgrade Project, the planed facility, named Sub-micron 3-D Diffraction (S3DD) beamline1, integrates the K-B mirror based polychromatic Laue diffraction and the Fresnel zone-plate based monochromatic diffraction techniques that currently support 3D/2D microdiffraction programs at the 34-ID-E and 2-ID-D of the APS, respectively. Both diffraction nanoprobes are designed to have a 50-nm or better special resolution. The zone-plate based monochromatic DNP has been preliminarily designed and will be constructed at the sector 34-ID. It uses an APS-3.0-cm period or APS-3.3-cm period undulator, a liquid-nitrogen cooled mirror as its first optics, and a water cooled small gap silicon double-crystal monochromator with an energy range of 5-30 keV. A set of zone plates have been designed to optimize for focusing efficiency and the working distance based on the attainable beamline length and the beam coherence. To ensure the nanoprobe performance, high stiffness and high precision flexure stage systems have been designed or demonstrated for optics mounting and sample scanning, and high precision temperature control of the experimental station will be implemented to reduce thermal instability. Designed nanoprobe beamline has a good management on thermal power loading on optical components and allows high degree of the preservation of beam brilliance for high focal flux and coherence. Integrated with variety of X-ray techniques, planed facility provides nano-XRD capability with the maximum reciprocal space accessibility and allows micro/nano-spectroscopy studies with K-edge electron binding energies of most elements down to Vanadium in the periodic table. We will discuss the preliminary design of the zone-plate

  11. Crustal movements at a divergent plate boundary: interplay between volcano deformation, geothermal processes, and plate spreading in the Northern Volcanic Zone, Iceland since 2008.

    NASA Astrophysics Data System (ADS)

    Drouin, Vincent; Sigmundsson, Freysteinn; Hreinsdóttir, Sigrún; Ofeigsson, Benedikt G.; Sturkell, Erik; Islam, Tariqul

    2014-05-01

    Iceland is a subaerial part of the Mid-Atlantic Ridge, where the divergent plate boundary between the North-American and Eurasian Plates can be studied. The Northern Volcanic Zone (NVZ) of Iceland, comprised of several volcanic systems, is particularly well suited to study interplay between volcanoes, geothermal areas and plate spreading, as the zone is relatively simple and accommodates the full spreading of the plates (18.6 mm/yr in a direction of 105 degrees according to NUVEL-1A predictions). The most recent volcanic activity in the area was the Krafla rifting episode (1975-1984). In 2007-2008 two intrusive events were detected: one in Upptypingar and the other in Þeistareykir. Extensive crustal deformation studies have been carried out in the NVZ; we report the results of recent GPS and Interferometric Synthetic Aperture Radar (InSAR) studies focusing on Krafla, Þeistareykir and Askja volcanic systems in the NVZ. An extensive GPS survey was undertaken in 2013, with over 135 stations occupied. This data was evaluated in conjunction with data acquired since 2008, to generate a velocity field spanning this entire time period. In addition to an existing continuous GPS (cGPS) station, three cGPS stations were installed in the area in 2011-2012. The 2008-2013 GPS velocities were compared to earlier GPS results, and complementary analysis of InSAR images was undertaken. Earlier studies have shown that the Krafla caldera underwent uplift during 1984-1989, followed by subsidence. Since 1995, the maximum subsidence in Krafla has shifted from directly above the shallow magma chamber towards an array of boreholes (geothermal exploitation) in Leirbotnar. Similar subsidence has been observed around another array of boreholes in Bjarnaflag, 7 km further south. The most significant signal on the velocities calculated from campaign GPS data over the 5 year period, is plate spreading with an E-W velocity of about 12 mm/yr over a 30 km wide area. However it also shows an

  12. Method for preparing surfaces of metal composites having a brittle phase for plating. [Patent application

    DOEpatents

    Coates, C.W.; Wilson, T.J.

    1982-05-19

    The present invention is directed to a method for preparing surfaces of two-phase metal composites having relatively brittle and malleable components for plating with corrosion-resistant material. In practice of the present invention, the surfaces of the composite are etched to remove a major portion or fraction of the brittle component. The etched surface is then peened with particulates for breaking the brittle component from the surfaces and for spreading or smearing the malleable component over the surfaces. The peened surface is then chemically cleaned of residual traces of the brittle component to which the corrosion-resistant material may be plated thereon in an adherent manner.

  13. Sub-crustal earthquakes within the Australia-Pacific plate boundary zone beneath the Southern Alps, New Zealand

    NASA Astrophysics Data System (ADS)

    Boese, C. M.; Stern, T. A.; Townend, J.; Bourguignon, S.; Sheehan, A.; Smith, E. G. C.

    2013-08-01

    Sub-crustal earthquakes have been observed sporadically for ∼40 years in the central South Island of New Zealand. We report on 20 events recorded between December 2008 and February 2012 near the Alpine Fault in the continental collision zone between the Australian and Pacific plates. A subset of 18 events at depths of 47-74 km occurs south of Mt. Cook and together with recently reported tremor locations indicates along-strike variations in deformation behaviour along the plate boundary. The sub-crustal earthquakes south of Mt. Cook increase in depth, frequency and size southwards towards the Puysegur subduction zone. Focal mechanisms could be determined for 14 earthquakes and exhibit predominantly strike-slip and reverse faulting solutions. Stress inversion analysis of the focal mechanisms yields a stress field favouring oblique-reverse faulting. We interpret the geographic and vertical distributions of these sub-crustal events in relation to a previously proposed tectonic model of a remnant passive margin that formed south of New Zealand in the Eocene and was overridden when dextral strike-slip motion initiated on the Alpine Fault. We infer that sub-crustal earthquakes occur along the leading edge of this structure, which is attached to the continental Australian crust.

  14. Overriding plate deformation and variability of fore-arc deformation during subduction: Insight from geodynamic models and application to the Calabria subduction zone

    NASA Astrophysics Data System (ADS)

    Chen, Zhihao; Schellart, Wouter P.; Duarte, João. C.

    2015-10-01

    In nature, subducting slabs and overriding plate segments bordering subduction zones are generally embedded within larger plates. Such large plates can impose far-field boundary conditions that influence the style of subduction and overriding plate deformation. Here we present dynamic laboratory models of progressive subduction in three-dimensional space, in which the far-field boundary conditions at the trailing edges of the subducting plate (SP) and overriding plate (OP) are varied. Four configurations are presented: Free (both plates free), SP-Fixed, OP-Fixed, and SP-OP-Fixed. We investigate their impact on the kinematics and dynamics of subduction, particularly focusing on overriding plate deformation. The results indicate that the variation in far-field boundary conditions has an influence on the slab geometry, subduction partitioning, and trench migration partitioning. Our models also indicate that in natural (narrow) subduction zones, assuming a homogeneous overriding plate, the formation of back-arc basins (e.g., Tyrrhenian Sea, Aegean Sea, and Scotia Sea) is generally expected to occur at a comparable location (250-700 km from the trench), irrespective of the boundary condition. In addition, our models indicate that the style of fore-arc deformation (shortening or extension) is influenced by the mobility of the overriding plate through controlling the force normal to the subduction zone interface (trench suction). Our geodynamic model that uses the SP-OP-Fixed setup is comparable to the Calabria subduction zone with respect to subduction kinematics, slab geometry, trench curvature, and accretionary configuration. Furthermore, the model can explain back-arc and fore-arc extension at the Calabria subduction zone since the latest middle Miocene as a consequence of subduction of the narrow Calabrian slab and the immobility of the subducting African plate and overriding Eurasian plate. This setting induced strong trench suction, driving fore-arc extension, and

  15. Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface

    PubMed Central

    Wang, Dacheng; Zhang, Lingchao; Gu, Yinghong; Mehmood, M. Q.; Gong, Yandong; Srivastava, Amar; Jian, Linke; Venkatesan, T.; Qiu, Cheng-Wei; Hong, Minghui

    2015-01-01

    Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices. PMID:26442614

  16. Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface

    NASA Astrophysics Data System (ADS)

    Wang, Dacheng; Zhang, Lingchao; Gu, Yinghong; Mehmood, M. Q.; Gong, Yandong; Srivastava, Amar; Jian, Linke; Venkatesan, T.; Qiu, Cheng-Wei; Hong, Minghui

    2015-10-01

    Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices.

  17. Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface.

    PubMed

    Wang, Dacheng; Zhang, Lingchao; Gu, Yinghong; Mehmood, M Q; Gong, Yandong; Srivastava, Amar; Jian, Linke; Venkatesan, T; Qiu, Cheng-Wei; Hong, Minghui

    2015-01-01

    Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices. PMID:26442614

  18. Plate interaction in the NE Caribbean subduction zone from continuous GPS observations

    USGS Publications Warehouse

    ten Brink, Uri S.; Lopez-Vegas, Alberto M.

    2012-01-01

    Kinematic similarities between the Sumatra and Puerto Rico Trenches highlight the potential for a mega-earthquake along the Puerto Rico Trench and the generation of local and trans-Atlantic tsunamis. We used the horizontal components of continuous GPS (cGPS) measurements from 10 sites on NE Caribbean islands to evaluate strain accumulation along the North American (NA) - Caribbean (CA) plate boundary. These sites move westward and slightly northward relative to CA interior at rates ≤2.5 mm/y. Provided this motion originates in the subduction interface, the northward motion suggests little or no trench-perpendicular thrust accumulation and may in fact indicate divergence north of Puerto Rico, where abnormal subsidence, bathymetry, and gravity are observed. The Puerto Rico Trench, thus, appears unable to generate mega-earthquakes, but damaging smaller earthquakes cannot be discounted. The westward motion, characterized by decreasing rate with distance from the trench, is probably due to eastward motion of CA plate impeded at the plate boundary by the Bahamas platform. Two additional cGPS sites in Mona Passage and SW Puerto Rico move to the SW similar to Hispaniola and unlike the other 10 sites. That motion relative to the rest of Puerto Rico may have given rise to seismicity and normal faults in Mona Rift, Mona Passage, and SW Puerto Rico.

  19. On gravity from SST, geoid from Seasat, and plate age and fracture zones in the Pacific

    NASA Technical Reports Server (NTRS)

    Marsh, B. D.; Marsh, J. G.; Williamson, R. G. (Principal Investigator)

    1984-01-01

    A composite map produced by combining 90 passes of SST data show good agreement with conventional GEM models. The SEASAT altimeter data were deduced and found to agree with both the SST and GEM fields. The maps are dominated (especially in the east) by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Comparison with regional bathymetric data shows a remarkedly close correlation with plate age. Most anomalies in the east half of the Pacific could be partly caused by regional differences in plate age. The amplitude of these geoid or gravity anomalies caused by age differences should decrease with absolute plate age, and large anomalies (approximately 3 m) over old, smooth sea floor may indicate a further deeper source within or perhaps below the lithosphere. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantle without complete thermal equilibration was considered. A plume emanating from a buoyant layer 100 km thick and 10,000 times less viscous than the surrounding mantle should have a diameter of about 400 km and must ascend at about 10 cm/yr to arrive still anomalously hot in the uppermost mantle.

  20. Tracking three-phase coexistences in binary mixtures of hard plates and spheres

    NASA Astrophysics Data System (ADS)

    Aliabadi, Roohollah; Moradi, Mahmood; Varga, Szabolcs

    2016-02-01

    The stability of demixing phase transition in binary mixtures of hard plates (with thickness L and diameter D) and hard spheres (with diameter σ) is studied by means of Parsons-Lee theory. The isotropic-isotropic demixing, which is found in mixtures of large spheres and small plates, is very likely to be pre-empted by crystallization. In contrast, the nematic-nematic demixing, which is obtained in mixtures of large plates and small spheres, can be stabilized at low diameter ratios (σ/D) and aspect ratios (L/D). At intermediate values of σ/D, where the sizes of the components are similar, neither the isotropic-isotropic nor the nematic-nematic demixing can be stabilized, but a very strong fractionation takes place between a plate rich nematic and a sphere rich isotropic phases. Our results show that the excluded volume interactions are capable alone to explain the experimental observation of the nematic-nematic demixing, but they fail in the description of isotropic-isotropic one [M. Chen et al., Soft Matter 11, 5775 (2015)].

  1. Miocene uplift of the NE Greenland margin linked to plate tectonics: Seismic evidence from the Greenland Fracture Zone, NE Atlantic.

    NASA Astrophysics Data System (ADS)

    Døssing, Arne; Japsen, Peter; Watts, Anthony; Nielsen, Tove; Jokat, Wilfried; Thybo, Hans

    2016-04-01

    Tectonic models predict that, following breakup, rift margins undergo only decaying thermal subsidence during their post-rift evolution. However, post-breakup stratigraphy beneath the NE Atlantic shelves shows evidence of regional-scale unconformities, commonly cited as outer margin responses to inner margin episodic uplift, including the formation of coastal mountains. The origin of these events remains enigmatic. We present a seismic reflection study from the Greenland Fracture Zone - East Greenland Ridge (GFZ-EGR) and the NE Greenland shelf. We document a regional intra-Miocene seismic unconformity (IMU), which marks the termination of syn-rift deposition in the deep-sea basins and onset of: (i) thermo-mechanical coupling across the GFZ, (ii) basin compression, and (iii) contourite deposition, north of the EGR. The onset of coupling across the GFZ is constrained by results of 2-D flexural backstripping. We explain the thermo-mechanical coupling and the deposition of contourites by the formation of a continuous plate boundary along the Mohns and Knipovich ridges, leading to an accelerated widening of the Fram Strait. We demonstrate that the IMU event is linked to onset of uplift and massive shelf-progradation on the NE Greenland margin. Given an estimated middle-to-late Miocene (~15-10 Ma) age of the IMU, we speculate that the event is synchronous with uplift of the East and West Greenland margins. The correlation between margin uplift and plate-motion changes further indicates that the uplift was triggered by plate tectonic forces, induced perhaps by a change in the Iceland plume (a hot pulse) and/or by changes in intra-plate stresses related to global tectonics.

  2. Free-Standing Zone Plate Optimized for He II 30.4 nm Solar Irradiance Measurements Having High Accuracy and Stability in Space

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; McMullin, D. R.; Vest, R.; Sakdinawat, A.; Chang, C.; Jones, A. R.; Bremer, J.

    2015-12-01

    A zone plate was designed to record the He II 30.4 nm solar irradiance, was fabricated using electron beam lithography, and was absolutely calibrated using the NIST SURF synchrotron. The zone plate has an open support grid identical to those used to successfully launch transmission gratings in previous solar radiometers and is otherwise free-standing with no support membrane that would absorb EUV radiation. The measured efficiency of 3.0 ± 0.1% at 30.4 nm is consistent with detailed modeling of the efficiency and accounting for the geometrical transmittance of the support grid. The binary nature of the zone plate, consisting of opaque gold bars and open spaces with no support membrane, results in excellent long-term stability in space against contamination, radiation damage, and other effects that could alter the efficiency and instrument throughput. The zone plate's focusing property enables the rejection of out-of-band radiation by small apertures and high signal to background values that are superior to previous radiometers. The 4 mm outer diameter of the zone plate and the 25 mm focal length for 30.4 nm radiation enable a compact instrument that is attractive for small CubeSats and other space flight missions where resources are extremely limited.

  3. Compact and Light-Weight Solar Spaceflight Instrument Designs Utilizing Newly Developed Miniature Free-Standing Zone Plates: EUV Radiometer and Limb-Scanning Monochromator

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; McMullin, D. R.; Bremer, J.; Chang, C.; Sakdinawat, A.; Jones, A. R.; Vest, R.

    2014-12-01

    Two solar instrument designs are presented that utilize newly developed miniature free-standing zone plates having interconnected Au opaque bars and no support membrane resulting in excellent long-term stability in space. Both instruments are based on a zone plate having 4 mm outer diameter and 1 to 2 degree field of view. The zone plate collects EUV radiation and focuses a narrow bandpass through a pinhole aperture and onto a silicon photodiode detector. As a miniature radiometer, EUV irradiance is accurately determined from the zone plate efficiency and the photodiode responsivity that are calibrated at the NIST SURF synchrotron facility. The EUV radiometer is pointed to the Sun and measures the absolute solar EUV irradiance in high time cadence suitable for solar physics and space weather applications. As a limb-scanning instrument in low earth orbit, a miniature zone-plate monochromator measures the extinction of solar EUV radiation by scattering through the upper atmosphere which is a measure of the variability of the ionosphere. Both instruments are compact and light-weight and are attractive for CubeSats and other missions where resources are extremely limited.

  4. 3D Simulation of the Entire Process of Earthquake Generation at Subduction-Zone Plate Boundaries

    NASA Astrophysics Data System (ADS)

    Matsu'Ura, M.; Hashimoto, C.; Fukuyama, E.

    2003-12-01

    In general, the entire process of earthquake generation consists of tectonic loading due to relative plate motion, quasi-static rupture nucleation, dynamic rupture propagation and stop, and restoration of fault strength. This process can be completely described by a coupled nonlinear system, which consists of an elastic/viscoelastic slip-response function that relates fault slip to shear stress change and a fault constitutive law that prescribes change in shear strength with fault slip and contact time. The shear stress and the shear strength are related with each other through boundary conditions on the fault. The driving force of this system is observed relative plate motion. The system to describe the earthquake generation cycle is conceptually quite simple. The complexity in practical modelling mainly comes from complexity in structure of the real earth. As a product of Crustal Activity Modelling Program (CAMP), which is one of the three main programs composing the Solid Earth Simulator project (1998-2003) promoted by MEXT, we have completed a physics-based predictive simulation model for the entire process of earthquake generation cycles in and around Japan, where the four plates of Pacific, North American, Philippine Sea and Eurasian are interacting with each other in a very complicated way. The total simulation system consists of a crust-mantle structure model, a tectonic loading model and a dynamic rupture model. First, we constructed a realistic 3D standard model of plate interfaces in and around Japan by applying an inversion technique to ISC hypocenter distribution data, and computed viscoelastic slip-response functions for this structure model. Second, we introduced the slip- and time-dependent fault constitutive law with an inherent strength-restoration mechanism as a basic equation governing the entire process of earthquake generation. Third, combining all these elements, we developed a simulation model for quasi-static stress accumulation due to

  5. Phase behaviour of liquid-crystal monolayers of rod-like and plate-like particles.

    PubMed

    Martínez-Ratón, Yuri; Varga, Szabolcs; Velasco, Enrique

    2014-05-28

    Orientational and positional ordering properties of liquid crystal monolayers are examined by means of Fundamental-Measure Density Functional Theory. Particles forming the monolayer are modeled as hard parallelepipeds of square section of size σ and length L. Their shapes are controlled by the aspect ratio κ = L/σ (>1 for prolate and <1 for oblate shapes). The particle centers of mass are restricted to a flat surface and three possible and mutually perpendicular orientations (in-plane and along the layer normal) of their uniaxial axes are allowed. We find that the structure of the monolayer depends strongly on particle shape and density. In the case of rod-like shapes, particles align along the layer normal in order to achieve the lowest possible occupied area per particle. This phase is a uniaxial nematic even at very low densities. In contrast, for plate-like particles, the lowest occupied area can be achieved by random in-plane ordering in the monolayer, i.e., planar nematic ordering takes place even at vanishing densities. It is found that the random in-plane ordering is not favorable at higher densities and the system undergoes an in-plane ordering transition forming a biaxial nematic phase or crystallizes. For certain values of the aspect ratio, the uniaxial-biaxial nematic phase transition is observed for both rod-like and plate-like shapes. The stability region of the biaxial nematic phase enhances with decreasing aspect ratios for plate-like particles, while the rod-like particles exhibit a reentrant phenomenon, i.e., a sequence of uniaxial-biaxial-uniaxial nematic ordering with increasing density if the aspect ratio is larger than 21.34. In addition to this, packing fraction inversion is observed with increasing surface pressure due to the alignment along the layers normal. At very high densities the nematic phase destabilizes to a nonuniform phases (columnar, smectic, or crystalline phases) for both shapes. PMID:24880324

  6. Volta phase plate cryo-EM of the small protein complex Prx3

    PubMed Central

    Khoshouei, Maryam; Radjainia, Mazdak; Phillips, Amy J.; Gerrard, Juliet A.; Mitra, Alok K.; Plitzko, Jürgen M.; Baumeister, Wolfgang; Danev, Radostin

    2016-01-01

    Cryo-EM of large, macromolecular assemblies has seen a significant increase in the numbers of high-resolution structures since the arrival of direct electron detectors. However, sub-nanometre resolution cryo-EM structures are rare compared with crystal structure depositions, particularly for relatively small particles (<400 kDa). Here we demonstrate the benefits of Volta phase plates for single-particle analysis by time-efficient cryo-EM structure determination of 257 kDa human peroxiredoxin-3 dodecamers at 4.4 Å resolution. The Volta phase plate improves the applicability of cryo-EM for small molecules and accelerates structure determination. PMID:26817416

  7. Fabrication of optical multilayer for two-color phase plate in super-resolution microscope

    NASA Astrophysics Data System (ADS)

    Iketaki, Yoshinori; Kitagawa, Katsuichi; Hidaka, Kohjiro; Kato, Naoki; Hirabayashi, Akira; Bokor, Nandor

    2014-07-01

    In super-resolution microscopy based on fluorescence depletion, the two-color phase plate (TPP) is an indispensable optical element, which can independently control the phase shifts for two beams of different color, i.e., the pump and erase beams. By controlling a phase shift of the erase beam through the TPP, the erase beam can be modulated into a doughnut shape, while the pump beam maintains the initial Gaussian shape. To obtain a reliable optical multiplayer (ML) for the TPP, we designed a ML with only two optical layers by performing numerical optimization. The measured phase shifts generated by the fabricated ML using interferometry correspond to the design values. The beam profiles in the focal plane are also consistent with theoretical results. Although the fabricated ML consists of only two optical layers, the ML can provide a suitable phase modulation function for the TPP in a practical super-resolution microscope.

  8. Fabrication of optical multilayer for two-color phase plate in super-resolution microscope

    SciTech Connect

    Iketaki, Yoshinori; Kitagawa, Katsuichi; Hidaka, Kohjiro; Kato, Naoki; Hirabayashi, Akira; Bokor, Nandor

    2014-07-15

    In super-resolution microscopy based on fluorescence depletion, the two-color phase plate (TPP) is an indispensable optical element, which can independently control the phase shifts for two beams of different color, i.e., the pump and erase beams. By controlling a phase shift of the erase beam through the TPP, the erase beam can be modulated into a doughnut shape, while the pump beam maintains the initial Gaussian shape. To obtain a reliable optical multiplayer (ML) for the TPP, we designed a ML with only two optical layers by performing numerical optimization. The measured phase shifts generated by the fabricated ML using interferometry correspond to the design values. The beam profiles in the focal plane are also consistent with theoretical results. Although the fabricated ML consists of only two optical layers, the ML can provide a suitable phase modulation function for the TPP in a practical super-resolution microscope.

  9. Beam quality changes of radially and azimuthally polarized fields propagating through quartic phase plates

    NASA Astrophysics Data System (ADS)

    Martínez-Herrero, R.; Piquero, G.; Mejías, P. M.

    2008-02-01

    In terms of the so-called irradiance moments of a light field, the beam quality change, Δ Q, of radially and azimuthally polarized beams caused by propagation through a quartic phase plate (as occurs, for example, in strongly pumped laser rods used in high-power solid-state lasers) is studied. Analytical expressions for Δ Q are given, and a comparison between the scalar and vectorial regimes is also shown. The results are applied to several cases of interest.

  10. Surface modes in "photonic cholesteric liquid crystal-phase plate-metal" structure.

    PubMed

    Vetrov, S Ya; Pyatnov, M V; Timofeev, I V

    2014-05-01

    The light transmission spectrum has been calculated for a "cholesteric liquid crystal-phase plate-metal" structure. It is shown that the system can have an isolated waveguide surface mode with characteristics efficiently controllable by external fields acting on the cholesteric. The degree of localization of surface modes and the transmission coefficients have been found to differ considerably for the light of different polarizations. PMID:24784092

  11. High-resolution high-efficiency multilayer Fresnel zone plates for soft and hard x-rays

    NASA Astrophysics Data System (ADS)

    Sanli, Umut T.; Keskinbora, Kahraman; Gregorczyk, Keith; Leister, Jonas; Teeny, Nicolas; Grévent, Corinne; Knez, Mato; Schütz, Gisela

    2015-09-01

    X-ray microscopy enables high spatial resolutions, high penetration depths and characterization of a broad range of materials. Calculations show that nanometer range resolution is achievable in the hard X-ray regime by using Fresnel zone plates (FZPs) if certain conditions are satisfied. However, this requires, among other things, aspect ratios of several thousands. The multilayer (ML) type FZPs, having virtually unlimited aspect ratios, are strong candidates to achieve single nanometer resolutions. Our research is focused on the fabrication of ML-FZPs which encompasses deposition of multilayers over a glass fiber via the atomic layer deposition (ALD), which is subsequently sliced in the optimum thickness for the X-ray energy by a focused ion beam (FIB). We recently achieved aberration free imaging by resolving 21 nm features with an efficiency of up to 12.5 %, the highest imaging resolution achieved by an ML-FZP. We also showed efficient focusing of 7.9 keV X-rays down to 30 nm focal spot size (FWHM). For resolutions below ~10 nm, efficiencies would decrease significantly due to wave coupling effects. To compensate this effect high efficiency, low stress materials have to be researched, as lower intrinsic stresses will allow fabrication of larger FZPs with higher number of zones, leading to high light intensity at the focus. As a first step we fabricated an ML-FZP with a diameter of 62 μm, an outermost zone width of 12 nm and 452 active zones. Further strategies for fabrication of high resolution high efficiency multilayer FZPs will also be discussed.

  12. Acoustic monitoring of earthquakes along the Blanco Transform Fault zone and Gorda Plate and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Dziak, Robert Paul

    Hydroacoustic tertiary (T-) waves are seismically generated acoustic waves that propagate over great distances in the ocean sound channel with little loss in signal strength. Hydrophone recorded T-waves can provide a lower earthquake detection threshold and an improved epicenter location accuracy for oceanic earthquakes than land-based seismic networks. Thus detection and location of NE Pacific ocean earthquakes along the Blanco Transform Fault (BTFZ) and Gorda plate using the U.S. Navy's SOSUS (SOund SUrveillance System) hydrophone arrays afford greater insight into the current state of stress and crustal deformation mechanics than previously available. Acoustic earthquake information combined with bathymetry, submersible observations, earthquake source- parameter estimates, petrologic samples, and water-column chemistry renders a new tectonic view of the southern Juan de Fuca plate boundaries. Chapter 2 discusses development of seismo-acoustic analysis techniques using the well-documented April 1992 Cape Mendocino earthquake sequence. Findings include a hydrophone detection threshold estimate (M ~ 2.4), and T-wave propagation path modeling to approximate earthquake acoustic source energy. Empirical analyses indicate that acoustic energy provides a reasonable magnitude and seismic moment estimate of oceanic earthquakes not detected by seismic networks. Chapters 3 documents a probable volcanogenic T-wave event swarm along a pull-apart basin within the western BTFZ during January 1994. Response efforts yielded evidence of anomalous water-column 3He concentrations, pillow- lava volcanism, and the first discovery of active hydrothermal vents along an oceanic fracture zone. Chapter 4 discusses the detection of a NE-SW trending microearthquake band along the mid-Gorda plate which was active from initiation of SOSUS recording in August 1991 through July 1992, then abruptly ceased. It is proposed that eventual termination of the Gorda plate seismicity band is due to

  13. High-resolution transmission electron microscopy with an electrostatic Zach phase plate

    NASA Astrophysics Data System (ADS)

    Hettler, S.; Dries, M.; Zeelen, J.; Oster, M.; Schröder, R. R.; Gerthsen, D.

    2016-05-01

    A new method to control lattice-fringe contrast in high-resolution transmission electron microscopy (HRTEM) images by the implementation of a physical phase plate (PP) is proposed. PPs are commonly used in analogy to Zernike PPs in light microscopy to enhance the phase contrast of weak-phase objects with nm-sized features, which often occur in life science applications. Such objects otherwise require strong defocusing, which leads to a degradation of the instrumental resolution and impedes intuitive image interpretation. The successful application of an electrostatic Zach PP in HRTEM is demonstrated by the investigation of single crystalline Si and Ge samples. The influence of the Zach PP on the image formation process is assessed by analyzing the amplitudes of (111) reflections in power spectra which show a cosine-type dependence on the induced phase shift under certain conditions as predicted by theory.

  14. In-Situ Observations of Earthquake-Driven Fluid Pulses within the Japan Trench Plate Boundary Fault Zone

    NASA Astrophysics Data System (ADS)

    Fulton, P. M.; Brodsky, E. E.

    2014-12-01

    Fault valving and transient fluid flow has long been suspected to be an important process in the earthquake cycle, but has not previously been captured by direct measurements during an episode. In particular, earthquakes are thought to drive fluids in fault zones, but again, evidence has been limited to the geologic record. Here we report on the signature of fluid pumping events inside the Tohoku Fault associated with individual earthquakes. As part of the Japan Trench Fast Drilling Project (JFAST), a sub-seafloor temperature observatory was installed across the plate boundary fault zone that ruptured during the 2011 Mw 9.0 Tohoku-oki earthquake. The observatory consisted of 55 autonomous temperature sensing dataloggers extending up to 820 m below sea floor at a water depth of ~7 km. The temporary deployment recorded data from July 2012 through April 2013. In addition to measuring the frictional heat signal from the megathrust earthquake, the high-resolution temperature time series data reveal spatially coherent temperature transients following regional earthquakes. Temperature increases vertically upwards from a fracture zone and decreases downwards, which is consistent with the expected signature of a pulse entering the annulus from the fracture zone. The anomalies are a few hundredths of degree Celsius and occur repeatedly at depths that are independently interpreted to have higher fracture permeability. High-pass filtered data are spatially correlated in areas disturbed by transient fluid advection. Fluid pulses occur in response to over a dozen local earthquakes, including a Mw 5.4 on 14 October 2012, a Mw 5.5 on 11 November 2012, and a doublet of two very local Mw 7.2 intraplate earthquakes on 7 December 2012, along with its associated aftershocks. There does not appear to be a response to large far-field earthquakes such as the 28 October 2012 Mw 7.8 Haida Gwaii or 6 February 2013 Mw 8.0 Santa Cruz Islands earthquakes. These measurements provide the first in

  15. Active tectonics west of New Zealand's Alpine Fault: South Westland Fault Zone activity shows Australian Plate instability

    NASA Astrophysics Data System (ADS)

    De Pascale, Gregory P.; Chandler-Yates, Nicholas; Dela Pena, Federico; Wilson, Pam; May, Elijah; Twiss, Amber; Cheng, Che

    2016-04-01

    The 300 km long South Westland Fault Zone (SWFZ) is within the footwall of the Central Alpine Fault (<20 km away) and has 3500 m of dip-slip displacement, but it has been unknown if the fault is active. Here the first evidence for SWFZ thrust faulting in the "stable" Australian Plate is shown with cumulative dip-slip displacements up to 5.9 m (with 3 m throw) on Pleistocene and Holocene sediments and gentle hanging wall anticlinal folding. Cone penetration test (CPT) stratigraphy shows repeated sequences within the fault scarp (consistent with thrusting). Optically stimulated luminescence (OSL) dating constrains the most recent rupture post-12.1 ± 1.7 ka with evidence for three to four events during earthquakes of at least Mw 6.8. This study shows significant deformation is accommodated on poorly characterized Australian Plate structures northwest of the Alpine Fault and demonstrates that major active and seismogenic structures remain uncharacterized in densely forested regions on Earth.

  16. Miocene uplift of the NE Greenland margin linked to plate tectonics: Seismic evidence from the Greenland Fracture Zone, NE Atlantic

    NASA Astrophysics Data System (ADS)

    Døssing, Arne; Japsen, Peter; Watts, Anthony B.; Nielsen, Tove; Jokat, Wilfried; Thybo, Hans; Dahl-Jensen, Trine

    2016-02-01

    Tectonic models predict that following breakup, rift margins undergo only decaying thermal subsidence during their postrift evolution. However, postbreakup stratigraphy beneath the NE Atlantic shelves shows evidence of regional-scale unconformities, commonly cited as outer margin responses to inner margin episodic uplift, including the formation of coastal mountains. The origin of these events remains enigmatic. We present a seismic reflection study from the Greenland Fracture Zone-East Greenland Ridge (GFZ-EGR) and the NE Greenland shelf. We document a regional intra-Miocene seismic unconformity (IMU), which marks the termination of synrift deposition in the deep-sea basins and onset of (i) thermomechanical coupling across the GFZ, (ii) basin compression, and (iii) contourite deposition, north of the EGR. The onset of coupling across the GFZ is constrained by results of 2-D flexural backstripping. We explain the thermomechanical coupling and the deposition of contourites by the formation of a continuous plate boundary along the Mohns and Knipovich ridges, leading to an accelerated widening of the Fram Strait. We demonstrate that the IMU event is linked to onset of uplift and massive shelf progradation on the NE Greenland margin. Given an estimated middle to late Miocene (~15-10 Ma) age of the IMU, we speculate that the event is synchronous with uplift of the east and west Greenland margins. The correlation between margin uplift and plate motion changes further indicates that the uplift was triggered by plate tectonic forces, induced perhaps by a change in the Iceland plume (a hot pulse) and/or by changes in intraplate stresses related to global tectonics.

  17. The Cell Cycle: An Activity Using Paper Plates to Represent Time Spent in Phases of the Cell Cycle

    ERIC Educational Resources Information Center

    Scherer, Yvette D.

    2014-01-01

    In this activity, students are given the opportunity to combine skills in math and geometry for a biology lesson in the cell cycle. Students utilize the data they collect and analyze from an online onion-root-tip activity to create a paper-plate time clock representing a 24-hour cell cycle. By dividing the paper plate into appropriate phases of…

  18. Seismic heating signatures in the Japan Trench subduction plate-boundary fault zone: evidence from a preliminary rock magnetic `geothermometer'

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Dekkers, Mark J.; Zhang, Bo

    2016-04-01

    Frictional heating during earthquake rupture reveals important information on earthquake mechanisms and energy dissipation. The amount of annealing varies widely and is, as yet, poorly constrained. Here we use magnetic susceptibility versus temperature measurements during cycling to increasingly elevated temperatures to constrain the maximum temperature a slip zone has experienced. The case study comprises sheared clay cored from the Japan Trench subduction plate-boundary fault zone (décollement), which accommodated the large slip of the 2011 Mw 9.0 Tohoku-oki earthquake. The décollement was cored during the Integrated Ocean Drilling Program (IODP) Expedition 343, the Japan Trench Fast Drilling Project (JFAST). Heating signatures with estimated maximum temperatures ranging from ˜300 to over 500 °C are determined close to the multiple slip surfaces within the décollement. Since it is impossible to tie a specific slip surface to a certain earthquake, thermal evidence for the cumulative effect of several earthquakes is unveiled. This as yet preliminary rock magnetic `geothermometer' would be a useful tool to detect seismic heating along faults that experienced medium temperature rise, a range which is difficult to assess with other approaches.

  19. Method for preparing surfaces of metal composites having a brittle phase for plating

    DOEpatents

    Coates, Cameron W.; Wilson, Thomas J.

    1984-01-01

    The present invention is directed to a method for preparing surfaces of two-phase metal composites having relatively brittle and malleable components for plating with corrosion-resistant material. In practice of the present invention, the surfaces of the composites are etched to remove a major portion or fraction of the brittle component. The etched surface is then peened with particulates for breaking the brittle component from the surfaces and for spreading or smearing the malleable component over the surfaces. The peened surface is then chemically cleaned of residual traces of the brittle component so as to provide a surface of essentially the malleable component to which the corrosion-resistant material may be plated thereon in an adherent manner.

  20. Method and apparatus for acoustic plate mode liquid-solid phase transition detection

    DOEpatents

    Blair, Dianna S.; Freye, Gregory C.; Hughes, Robert C.; Martin, Stephen J.; Ricco, Antonio J.

    1993-01-01

    A method and apparatus for sensing a liquid-solid phase transition event is provided which comprises an acoustic plate mode detecting element placed in contact with a liquid or solid material which generates a high-frequency acoustic wave that is attenuated to an extent based on the physical state of the material is contact with the detecting element. The attenuation caused by the material in contact with the acoustic plate mode detecting element is used to determine the physical state of the material being detected. The method and device are particularly suited for detecting conditions such as the icing and deicing of wings of an aircraft. In another aspect of the present invention, a method is provided wherein the adhesion of a solid material to the detecting element can be measured using the apparatus of the invention.

  1. Detection and quantification of delamination in laminated plates from the phase of appropriate guided wave modes

    NASA Astrophysics Data System (ADS)

    Amjad, Umar; Yadav, Susheel Kumar; Kundu, Tribikram

    2016-01-01

    Applicability of specific Lamb wave modes for delamination detection and quantification in a laminated aluminum plate is investigated. The Lamb modes were generated in the plate using a broadband piezoelectric transducer structured with a rigid electrode. Appropriate excitation frequencies and modes for inspection were selected from theoretical dispersion curves. Sensitivity of antisymmetric and symmetric modes for delamination detection and quantification has been investigated using the Hilbert-Huang transform. The mode conversion phenomenon of Lamb waves during progressive delamination is observed. The antisymmetric mode is found to be more reliable for delamination detection and quantification. In this investigation, the changes in the phase of guided Lamb wave modes are related to the degree of delamination, unlike other studies, where mostly the attenuation of the propagating waves has been related to the extent of the internal damage, such as cracks and corrosions. Appropriate features for delamination detection and quantification are extracted from the experimental data.

  2. Mantle convection with plates and mobile, faulted plate margins.

    PubMed

    Zhong, S; Gurnis, M

    1995-02-10

    A finite-element formulation of faults has been incorporated into time-dependent models of mantle convection with realistic rheology, continents, and phase changes. Realistic tectonic plates naturally form with self-consistent coupling between plate and mantle dynamics. After the initiation of subduction, trenches rapidly roll back with subducted slabs temporarily laid out along the base of the transition zone. After the slabs have penetrated into the lower mantle, the velocity of trench migration decreases markedly. The inhibition of slab penetration into the lower mantle by the 670-kilometer phase change is greatly reduced in these models as compared to models without tectonic plates. PMID:17813909

  3. Aquitard contaminant storage and flux resulting from dense nonaqueous phase liquid source zone dissolution and remediation

    EPA Science Inventory

    A one-dimensional diffusion model was used to investigate the effects of dense non-aqueous phase liquid (DNAPL) source zone dissolution and remediation on the storage and release of contaminants from aquitards. Source zone dissolution was represented by a power-law source depleti...

  4. Continuous monitoring of an active fault in a plate suture zone: a creepmeter study of the Chihshang Fault, eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Lee, J.-C.; Angelier, J.; Chu, H.-T.; Hu, J.-C.; Jeng, F.-S.

    2001-04-01

    Data from continuously monitored creepmeters across the active Chihshang Fault in eastern Taiwan are presented. The Chihshang Fault is an active segment of the Longitudinal Valley Fault, the main suture between the converging Philippine and Eurasian plates in Taiwan. Since the 1951 earthquake (Mw=7.0), no earthquake larger than magnitude 6.0 occurred in the Chihshang area. At least during the last 20 years, the Chihshang Fault underwent a steady creep movement, resulting in numerous fractures at the surface. Five creepmeters were installed in 1998 at two sites, Tapo and Chinyuan, within the Chihshang active fault zone. One-year results (from August 1998 to July 1999) show a horizontal shortening of 19.4±0.3 mm and 17.3±0.7 mm, at Tapo and Chinyuan, respectively. These annual shortening rates are in a good agreement with other estimates of strain rate independently obtained from geodetic measurements and geological site investigation. The creepmeter measurements were made on a daily basis, providing accurate information on the previously unknown evolution of creep during the year. The records of fault creep at the Tapo site thus revealed close seasonal correlation with average rainfall: the period of high creep rate coincides with the wet season, whereas that of low creep rate coincides with the dry season. Also, in comparison with the Tapo site, the creep behaviour as a function of time is complex at the Chinyuan site. Possible factors of irregularity are under investigation (thermal effect acting on the concrete basement of the creepmeters, earth tide effect, water table variations in a nearby rice field, and rainfall). The comparison between GPS measurements across the Longitudinal Valley (31 mm/year of horizontal displacement) and the creepmeter measurement across the Chihshang Fault zone (17-19 mm/year of horizontal displacement) suggests that there exists other shortening deformation across the active fault zone in addition to those we have measured from the

  5. On pressure-shear plate impact for studying the kinetics of stress-induced phase transformations

    NASA Astrophysics Data System (ADS)

    Escobar, Joanne C.; Clifton, Rodney J.

    1992-07-01

    Pressure-shear plate impact experiments are proposed for studying the kinetics of stress-induced phase transformations. The purpose of this paper is to determine loading conditions and specimen orientations which can be expected to activate a single habit plane variant parallel to the impact plane, thereby simplifying the study of the kinetics of the transformation through monitoring the wave profiles associated with the propagating phase boundary. The Wechsler Lieberman-Read phenomenological theory was used to determine habit plane indices and directions of shape deformation for a Cu-Al-Ni shape memory alloy which undergoes a martensitic phase transformation under stress. Elastic waves generated by pressure-shear impact were analyzed for wave propagation in the direction of the normal to a habit plane. A critical resolved shear stress criterion was used to predict variants which are expected to be activated for a range of impact velocities and relative magnitudes of the normal and transverse components of the impact velocity.

  6. Deciphering the mechanics of an imaged fault system in the over-riding plate at the Shumagin Seismic Gap, Alaska subduction zone using MCS waveform tomography

    NASA Astrophysics Data System (ADS)

    Michaelson, C. A.; Delescluse, M.; Becel, A.; Nedimovic, M. R.; Shillington, D. J.; Louden, K. E.; Webb, S. C.

    2013-12-01

    The 2011 ALEUT program acquired 3500 km of multichannel seismic (MCS) data along a part of the western Alaska subduction zone, from the freely slipping Shumagin Seismic Gap to the locked regions in the Semidi segment and the western Kodiak asperity. The MCS profiles were acquired on the R/V Langseth using two 8-km-long streamers and span the entire locked zone on the megathrust, including the updip and downdip transitions to stable sliding. The primary goal was to characterize variations in the geometry and properties of the megathrust and the downgoing plate and relate them to downdip and along-strike changes in slip behavior and seismogenesis. The images capture the targeted megathrust reflectivity and its spatial variation. Notably, the two westernmost profiles show reflections arising from a major fault in the overriding plate within the Shumagin Seismic Gap located 75 km from the trench, which can be followed from the seafloor to the megathrust. The imaged normal fault bounds the seaward end of the Sanak forearc Cenozoic basin, formed after the Early Eocene reorganization of the Alaska subduction zone. The new reflection images also show that the seaward pair of the previously interpreted growth faults, thought to indicate deposition contemporaneous with basin subsidence, is a part of the imaged fault system. The unexpected imaging of this major fault system in the over-riding plate raises important questions: Has this fault been active during the most recent nearby megathrust earthquakes, such as the 1946 and 1948 earthquakes? Was the Sanak basin formed as a result of slip on the imaged normal fault system or is it a result of growth faulting that predates the formation of this fault? The timing and style of deformation on this fault has significant implications for both coupling on the megathrust seaward and landward of where the normal fault roots and tsunamigenesis. To complement constraints on the geometry and reflection characteristics of this structure

  7. Young tectonics of a complex plate boundary zone: Indentation, rotation, and escape in Alaska

    NASA Astrophysics Data System (ADS)

    Wallace, W. K.; Ruppert, N. A.

    2012-12-01

    Convergence of thick crust of the Yakutat block with the southern margin of Alaska is widely recognized as a dominant influence on the tectonics of Alaska since at least late Miocene time. It is less clear how this convergence relates to the distribution, type, and orientation of geologic structures, and to the boundaries between the tectonic provinces that they define. We propose that convergence of Yakutat block includes two distinct components that influence deformation and topography in different ways: 1) The crust of the exposed, southern Yakutat block is too thick to subduct, which has caused the collisional St. Elias orogen. Detachment of the upper part of the mafic basement allows delamination and sinking of the remaining mafic crust and lithospheric mantle. The collisional orogen drives rigid counterclockwise rotation of the southern Alaska block south of the arcuate, right-lateral Denali fault. The western boundary of this block is a zone of distributed contraction in the western Alaska Range and Cook Inlet. 2) The northern part of the Yakutat block is thin enough to subduct but thick and buoyant enough to cause localized flat-slab subduction orthogonal to rotation of the southern Alaska block. Consequences include the gently antiformal Talkeetna Mountains that span the forearc basin, a gap in the magmatic arc, and a basement-involved fold-and-thrust belt in the northern Alaska Range. An arcuate oroclinal hinge from southern Alaska to the northeastern Brooks Range reflects indentation since at least Paleocene time. Traction above the subducted Yakutat block along the southern part of this hinge drives current indentation. North of the subducted Yakutat block, indentation is reflected by left-lateral block rotation that accommodates shortening between the Denali and Tintina faults and by contraction farther north along the northern edge of the arcuate northeastern Brooks Range. Western Alaska accommodates both northward indentation and westward convergence

  8. Local orbital angular momentum revealed by spiral-phase-plate imaging in transmission-electron microscopy

    NASA Astrophysics Data System (ADS)

    Juchtmans, Roeland; Verbeeck, Jo

    2016-02-01

    The orbital angular momentum (OAM) of light and matter waves is a parameter that has been getting increasingly more attention over the past couple of years. Beams with a well-defined OAM, the so-called vortex beams, are applied already in, e.g., telecommunication, astrophysics, nanomanipulation, and chiral measurements in optics and electron microscopy. Also, the OAM of a wave induced by the interaction with a sample has attracted a lot of interest. In all these experiments it is crucial to measure the exact (local) OAM content of the wave, whether it is an incoming vortex beam or an exit wave after interacting with a sample. In this work we investigate the use of spiral phase plates (SPPs) as an alternative to the programmable phase plates used in optics to measure OAM. We derive analytically how these can be used to study the local OAM components of any wave function. By means of numerical simulations we illustrate how the OAM of a pure vortex beam can be measured. We also look at a sum of misaligned vortex beams and show how, by using SPPs, the position and the OAM of each individual beam can be detected. Finally, we look at the OAM induced by a magnetic dipole on a free-electron wave and show how the SPP can be used to localize the magnetic poles and measure their "magnetic charge." Although our findings can be applied to study the OAM of any wave function, our findings are of particular interest for electron microscopy where versatile programmable phase plates do not yet exist.

  9. Experimental investigation on focusing characteristics of a He-Ne laser using circular Fresnel zone plate for high-precision alignment of linear accelerators

    SciTech Connect

    Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi; Minoshima, Kaoru

    2012-05-15

    We experimentally investigate the focusing characteristics of a He-Ne laser at the focal region for the high-precision alignment of long-distance linear accelerators using a circular Fresnel zone plate. The laser wave passing through the Fresnel zone plate having a focal length of 66.7 m propagates for a 268-m-long distance at atmospheric pressure. A new laser-based alignment system using Fresnel zone plates as the alignment targets is discussed. The transverse displacement of the focused spot of the laser is measured as a function of the displacement of the target by a detector installed at the focal point. Systematic studies on the focusing characteristics and alignment precision have been successfully conducted in this experiment. The experimental results are in good agreement with theoretical calculations, and the alignment precision of the target is determined to be less than {+-}30 {mu}m. In this study, we perform a detailed experimental investigation on the laser propagation and focusing characteristics using the circular Fresnel zone plate at the focal region along with theoretical calculations.

  10. Wide spectral range multiple orders and half-wave achromatic phase retarders fabricated from two lithium tantalite single crystal plates

    NASA Astrophysics Data System (ADS)

    Emam-Ismail, M.

    2015-11-01

    In a broad spectral range (300-2500 nm), we report the use of channeled spectra formed from the interference of polarized white light to extract the dispersion of the phase birefringence Δnp(λ) of the x- and y-cuts of lithium tantalite (LiTaO3:LT) plates. A new method named as wavenumber difference method is used to extract the spectral behavior of the phase birefringence of the x- and y- cuts of LT plates. The correctness of the obtained birefringence data is confirmed by using Jones vector method through recalculating the plates thicknesses. The spectral variation of the phase birefringence Δnp(λ) of the x- and y-cuts of LT plates is fitted to Cauchy dispersion function with relative error for both x- and y-cuts of order 2.4×10-4. The group birefringence dispersion Δng (λ) of the x- and y-cuts of LT plates is also calculated and fitted to Ghosh dispersion function with relative error for both x- and y-cuts of order 2.83×10-4. Furthermore, the phase retardation introduced by the x- and y-cuts of LT plates is also calculated. It is found that the amount of phase retardation confirms that the x- and y-cuts of LT plates can act as a multiple order half- and quarter-wave plates working at many different wavelengths through the spectral range 300-2500 nm. For the x- and y-cuts of LT plates, a large difference between group and phase birefringence is observed at a short wavelength (λ=300 nm); while such difference progressively diminished at longer wavelength (λ=2000 nm). In the near infrared region (NIR) region (700-2500 nm), a broad spectral full width at half maximum (FWHM) is observed for either x- or y-cut of LT plate which can act as if it is working as a zero order wave plate. Finally, an achromatic half-wave plate working at 598 nm and covering a wide spectral range (300-900 nm) is demonstrated experimentally by combining both x- and y-cuts of LT plates.

  11. Fabrication and evaluation of a weak zone plate for monitoring performance of large orbiting telescopes

    NASA Technical Reports Server (NTRS)

    Erickson, K. E.

    1972-01-01

    An experimental study of the feasibility of monitoring the optical performance of a large telescope by means of a very faint phase hologram imprinted upon the primary mirror is reported. Tests have been made using an f/5 telescope with a 0.3 m aperture. The results indicate that a usable hologram can be so faint and so restricted in area that it will probably not interfere significantly with normal operation of a 3.0 m telescope at wavelengths longer than 100 nm for stars brighter than magnitude 29.

  12. Micro-Fresnel Zone Plate Optical Devices Using Densely Accumulated Ray Points

    NASA Technical Reports Server (NTRS)

    Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2011-01-01

    An embodiment generally relates to an optical device suitable for use with an optical medium for the storage and retrieval of data. The optical device includes an illumination means for providing a beam of optical radiation of wavelength .lamda. and an optical path that the beam of optical radiation follows. The optical device also includes a diffractive optical element defined by a plurality of annular sections. The plurality of annular sections having a first material alternately disposed with a plurality of annular sections comprising a second material. The diffractive optical element generates a plurality of focal points and densely accumulated ray points with phase contrast phenomena and the optical medium is positioned at a selected focal point or ray point of the diffractive optical element.

  13. Ultra-thin optical vortex phase plate based on the metasurface and the angular momentum transformation

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Li, Yan; Guo, Zhongyi; Li, Rongzhen; Zhang, Jingran; Zhang, Anjun; Qu, Shiliang

    2015-04-01

    The ultra-thin optical vortex phase plate (VPP) has been designed and investigated based on the metasurface of the metal rectangular split-ring resonators (MRSRRs) array. The circularly polarized incident light can convert into corresponding cross-polarization transmission light, and the phase and the amplitude of cross-polarization transmission light can be simultaneously governed by modulating two arms of the MRSRR. The MRSRR has been arranged in a special order for forming an ultra-thin optical VPP that can covert a plane wave into a vortex beam with a variety of the topological charges, and the transformation between spin angular momentum (SAM) and orbital angular momentum (OAM) has been discussed in detail. The multi-spectral characteristics of the VPP have also been investigated, and the operating bandwidth of the designed VPP is 190 nm (in the range of 710-900 nm), which enable a potential implication for integrated optics and vortex optics.

  14. Coherent x-ray diffraction imaging of paint pigment particles by scanning a phase plate modulator

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Zhang, Fucai; Berenguer, Felisa; Bean, Richard J.; Kewish, Cameron M.; Vila-Comamala, Joan; Chu, Yong S.; Rodenburg, John M.; Robinson, Ian K.

    2011-10-01

    We have implemented a coherent x-ray diffraction imaging technique that scans a phase plate to modulate wave-fronts of the x-ray beam transmitted by samples. The method was applied to measure a decorative alkyd paint containing iron oxide red pigment particles. By employing an iterative algorithm for wave-front modulation phase retrieval, we obtained an image of the paint sample that shows the distribution of the pigment particles and is consistent with the result obtained from a transmission x-ray microscope. The technique has been experimentally proven to be a feasible coherent x-ray imaging method with about 120 nm spatial resolution and was shown to work well with industrially relevant specimens.

  15. Coherent x-ray diffraction imaging of paint pigmentparticles by scanning a phase plate modulator

    SciTech Connect

    Chu Y. S.; Chen B.; Zhang F.; Berenguer F.; Bean R.; Kewish C.; Vila-Comamala J.; Rodenburg J.; Robinson I.

    2011-10-19

    We have implemented a coherent x-ray diffraction imaging technique that scans a phase plate to modulate wave-fronts of the x-ray beam transmitted by samples. The method was applied to measure a decorative alkyd paint containing iron oxide red pigment particles. By employing an iterative algorithm for wave-front modulation phase retrieval, we obtained an image of the paint sample that shows the distribution of the pigment particles and is consistent with the result obtained from a transmission x-ray microscope. The technique has been experimentally proven to be a feasible coherent x-ray imaging method with about 120 nm spatial resolution and was shown to work well with industrially relevant specimens.

  16. Overview of the multilayer-Fresnel zone plate and the kinoform lens development at MPI for intelligent systems

    NASA Astrophysics Data System (ADS)

    Tunca Sanli, Umut; Keskinbora, Kahraman; Grévent, Corinne; Schütz, Gisela

    2015-05-01

    The ultimate goal of our research is to develop novel fabrication methods for high efficiency and high resolution X-ray optics. To this end, we have been pursuing the fabrication of several innovative diffractive/refractive optics designs. One such optic is the multilayer type Fresnel zone plate (ML-FZP). Our fabrication process relies on the atomic layer deposition (ALD) of two materials on a smooth glass fiber followed by a focused ion beam (FIB) based slicing and polishing. The ALD process allows much smaller outermost zone widths than the standard electron beam lithography based FZPs, meaning FZPs with potentially higher resolutions. Moreover, by depositing the multilayer on a cm long glass-fiber FZPs with very high optical thicknesses can be fabricated that can efficiently focus harder X-rays as well. A 21 nm half-pitch resolution was achieved using the ML-FZPs. Another optic we have been working on is the kinoform lens, which is a refractive/diffractive optic with a 100 % theoretical focusing efficiency. Their fabrication is usually realized by using approximate models which limit their success. Recently the fabrication of real kinoform lenses has been successfully realized in our lab via gray-scale direct-write ion beam lithography without any approximations. The lenses have been tested in the soft X-ray range achieving up to ~90 % of the calculated efficiency which indicates outstanding replication of the designed profile. Here we give an overview of our research and discuss the future challenges and opportunities for these optics.

  17. New long trace profiler based on phase plate diffraction for optical metrology of SSRF

    SciTech Connect

    Zeng Danhua; Xiao Tiqiao; Du Guohao; Wen Li; Luo Hongxin; Xia Shaojian; Xu Hongjie

    2006-09-15

    A long trace profiler LTP-1200, with a novel f-{theta} system based on phase plate diffraction and a scanning range up to 1200 mm, has been developed at Shanghai Synchrotron Radiation Facility. The central dark line in the diffraction pattern generated by a {pi} phase plate is taken as the positioning benchmark. A magnet levitated linear rail with very high accuracy is used. A granite bench is employed to reduce deformation due to self-gravity of the rail. The focused diffraction pattern is recorded with an area charge-coupled device. The generalized regression neural network algorithm is adopted to improve the beam positioning precision. The static stability of LTP-1200 in 5 h is 0.14 {mu}rad, and the repeatability reaches 0.05 {mu}rad in a common laboratory without any special control of temperature, air turbulence, etc. Calibration tests were carried out with a high precision autocollimator and a standard spherical mirror, respectively. Results show the high performance and reliability of the LTP-1200.

  18. Identifying active interplate and intraplate fault zones in the western Caribbean plate from seismic reflection data and the significance of the Pedro Bank fault zone in the tectonic history of the Nicaraguan Rise

    NASA Astrophysics Data System (ADS)

    Ott, B.; Mann, P.

    2015-12-01

    The offshore Nicaraguan Rise in the western Caribbean Sea is an approximately 500,000 km2 area of Precambrian to Late Cretaceous tectonic terranes that have been assembled during the Late Cretaceous formation of the Caribbean plate and include: 1) the Chortis block, a continental fragment; 2) the Great Arc of the Caribbean, a deformed Cretaceous arc, and 3) the Caribbean large igneous province formed in late Cretaceous time. Middle Eocene to Recent eastward motion of the Caribbean plate has been largely controlled by strike-slip faulting along the northern Caribbean plate boundary zone that bounds the northern margin of the Nicaraguan Rise. These faults reactivate older rift structures near the island of Jamaica and form the transtensional basins of the Honduran Borderlands near Honduras. Recent GPS studies suggest that small amount of intraplate motion within the current margin of error of GPS measurements (1-3 mm/yr) may occur within the center of the western Caribbean plate at the Pedro Bank fault zone and Hess Escarpment. This study uses a database of over 54,000 km of modern and vintage 2D seismic data, combined with earthquake data and results from previous GPS studies to define the active areas of inter- and intraplate fault zones in the western Caribbean. Intraplate deformation occurs along the 700-km-long Pedro Bank fault zone that traverses the center of the Nicaraguan Rise and reactivates the paleo suture zone between the Great Arc of the Caribbean and the Caribbean large igneous province. The Pedro Bank fault zone also drives active extension at the 200-km-long San Andres rift along the southwest margin of the Nicaraguan Rise. Influence of the Cocos Ridge indentor may be contributing to reactivation of faulting along the southwesternmost, active segment of the Hess Escarpment.

  19. Hard X-ray Spectroscopy and Imaging by a Reflection Zone Plate in the Presence of Astigmatism

    SciTech Connect

    Braig, Christoph; Lochel, Heike; Hafner, Aljosa; Firsov, Alexander; Rehanek, Jens; Brzhezinskaya, Maria; Wojcik, Michael; Macrander, Albert; Assoufid, Lahsen; Erko, Alexei

    2016-01-01

    The feasibility of an off-axis x-ray reflection zone plate to perform wavelength-dispersive spectroscopy, on-axis point focusing, and two-dimensional imaging is demonstrated by means of one and the same diffractive optical element (DOE) at a synchrotron radiation facility. The resolving power varies between 3×101 and 4×102 in the range of 7.6 keV to 9.0 keV, with its maximum at the design energy of 8.3 keV. This result is verified using an adjustable entrance slit, by which horizontal (H) and vertical (V) focusing to 0.85 μm(H) and 1.29 μm(V) is obtained near the sagittal focal plane of the astigmatic configuration. An angular and axial scan proves an accessible field of view of at least 0.6 arcmin × 0.8 arcmin and a focal depth of ±0.86 mm. Supported by the grating efficiency of around 17.5% and a very short pulse elongation, future precision x-ray fluorescence and absorption studies of transition metals at their K-edge on an ultrashort timescale could benefit from our findings.

  20. Along-axis variations within the plate boundary zone of the southern segment of the Endeavour Ridge

    NASA Astrophysics Data System (ADS)

    Barone, Angela M.; Ryan, William B. F.

    1988-07-01

    The width of and along-axis variations within the plate boundary zone of the southern segment of the Endeavour Ridge of the Juan de Fuca Ridge System have been quantified using Sea MARC I side-looking sonar imagery. The sonar imagery was calibrated with video and photographic surveying to provide visual corroboration of the activity, spacing, and offset of faults and fissures. This ridge segment contains an axial high bisected along its length by a summit depression whose width, relief of its rims, depth of its floor, and spacing of faults and fissures vary systematically away from the mid-point of the ridge segment toward its tips. The axial high and its summit depression are likened to an elongated shield volcano that is being disrupted by collapse of its crest into a widening linear caldera. The observed distribution of faults and fissures could be produced by mechanisms which stretch young ocean crust which is characterized by rheological properties which vary with distance from the center of the elongated volcano.

  1. Hard x-ray spectroscopy and imaging by a reflection zone plate in the presence of astigmatism.

    PubMed

    Braig, Christoph; Löchel, Heike; Firsov, Alexander; Brzhezinskaya, Maria; Hafner, Aljosa; Rehanek, Jens; Wojcik, Michael; Macrander, Albert; Assoufid, Lahsen; Erko, Alexei

    2016-01-01

    The feasibility of an off-axis x-ray reflection zone plate to perform wavelength-dispersive spectroscopy, on-axis point focusing, and two-dimensional imaging is demonstrated by means of one and the same diffractive optical element (DOE) at a synchrotron radiation facility. The resolving power varies between 3×101 and 4×102 in the range of 7.6 keV to 9.0 keV, with its maximum at the design energy of 8.3 keV. This result is verified using an adjustable entrance slit, by which horizontal (H) and vertical (V) focusing to 0.85 μm(H) and 1.29 μm(V) is obtained near the sagittal focal plane of the astigmatic configuration. An angular and axial scan proves an accessible field of view of at least 0.6 arcmin × 0.8 arcmin and a focal depth of ±0.86  mm. Supported by the grating efficiency of around 17.5% and a very short pulse elongation, future precision x-ray fluorescence and absorption studies of transition metals at their K-edge on an ultrashort timescale could benefit from our findings. PMID:26696150

  2. Ultra Low Velocity Zone existence in the high shear velocity region beneath Cocos Plate, Central America, and the Caribbean

    NASA Astrophysics Data System (ADS)

    Yu, S.; Garnero, E.; Shim, S. H. D.; Zhao, C.

    2014-12-01

    The lowermost mantle beneath subduction is typically characterized by higher than average shear wave speeds, often with the presence of one or more D" discontinuities. These regions are considered the cooler parts of the convective cycle, in contrast to warmer zones of convective return flow, namely, the vicinity of large low shear velocity provinces (LLSVPs). Ultra-low velocity zones (ULVZs) have been long characterized as related to elevated temperature (and/or chemistry) of LLSVP regions. However, some past work has suggested evidence for ULVZ in the presumed cooler regions. In this study we investigate the region beneath the Cocos Plate, Central America, and the Carribbean for ULVZ using high quality broadband Transportable Array data from EarthScope's USArray for the presence of ULVZs. We utilize an ScS-stripping technique that combines a precursor and postcursor to ScS that arise from ULVZ structure, if present. The precursor is a reflection off the top of the ULVZ, while the postcursor is a core-reflection with an added reverberation between the ULVZ top and the core-mantle boundary (CMB). We collected data from deep South American earthquakes recorded in North America and stack data in geographic bins. We find clear evidence for a ULVZ beneath the Gulf of Mexico, but the rest of the study area appears to lack any significant structure. The structure we find is of the order of 100 km wide. The ULVZ properties will be constrained by comparison to predictions from synthetic seismograms. We explore hypotheses for the origin of a ULVZ in a high shear velocity region. These include mineralogical heterogeneities that convective currents have collected; notable possibilities are accumulated melts from subducted materials, such as ocean crust basalts and banded-iron formation. If water can be transported by subducted slabs to the deep mantle, it can significantly decrease the melting temperature of mantle materials and cause such anomalies. A ULVZ a relatively cold

  3. Distribution and migration of aftershocks of the 2010 Mw 7.4 Ogasawara Islands intraplate normal-faulting earthquake related to a fracture zone in the Pacific plate

    NASA Astrophysics Data System (ADS)

    Obana, Koichiro; Takahashi, Tsutomu; No, Tetsuo; Kaiho, Yuka; Kodaira, Shuichi; Yamashita, Mikiya; Sato, Takeshi; Nakamura, Takeshi

    2014-04-01

    describe the aftershocks of a Mw 7.4 intraplate normal-faulting earthquake that occurred 150 km east Ogasawara (Bonin) Islands, Japan, on 21 December 2010. It occurred beneath the outer trench slope of the Izu-Ogasawara trench, where the Pacific plate subducts beneath the Philippine Sea plate. Aftershock observations using ocean bottom seismographs (OBSs) began soon after the earthquake and multichannel seismic reflection surveys were conducted across the aftershock area. Aftershocks were distributed in a NW-SE belt 140 km long, oblique to the N-S trench axis. They formed three subparallel lineations along a fracture zone in the Pacific plate. The OBS observations combined with data from stations on Chichi-jima and Haha-jima Islands revealed a migration of the aftershock activity. The first hour, which likely outlines the main shock rupture, was limited to an 80 km long area in the central part of the subsequent aftershock area. The first hour activity occurred mainly around, and appears to have been influenced by, nearby large seamounts and oceanic plateau, such as the Ogasawara Plateau and the Uyeda Ridge. Over the following days, the aftershocks expanded beyond or into these seamounts and plateau. The aftershock distribution and migration suggest that crustal heterogeneities related to a fracture zone and large seamounts and oceanic plateau in the incoming Pacific plate affected the rupture of the main shock. Such preexisting structures may influence intraplate normal-faulting earthquakes in other regions of plate flexure prior to subduction.

  4. Continuous distributed phase-plate advances for high-energy laser systems

    NASA Astrophysics Data System (ADS)

    Marozas, J. A.; Collins, T. J. B.; Zuegel, J. D.; McKenty, P. W.; Cao, D.; Fochs, S.; Radha, P. B.

    2016-05-01

    The distributed phase plate (DPP) design code Zhizhoo’ has been used to design full- aperture, continuous near-field transmission optics for a wide variety of high-fidelity focal-spot shapes for high-energy laser systems: OMEGA EP, Dynamic Compression Sector (DCS), and the National Ignition Facility (NIF). The envelope shape, or profile, of the focal spot affects the hydrodynamics of directly driven targets in these laser systems. Controlling the envelope shape to a high degree of fidelity impacts the quality of the ablatively driven implosions. The code Zhizhoo’ not only produces DPP's with great control of the envelope shape, but also spectral and gradient control as well as robustness from near-field phase aberrations. The focal-spot shapes can take on almost any profile from symmetric to irregular patterns and with high fidelity relative to the objective function over many decades of intensity. The control over the near-field phase spectrum and phase gradients offer greater manufacturability of the full- aperture continuous surface-relief pattern. The flexibility and speed of the DPP design code Zhizhoo’ will be demonstrated by showing the wide variety of successful designs that have been made and those that are in progress.

  5. Concrete containment tests: Phase 2, Structural elements with liner plates: Interim report

    SciTech Connect

    Hanson, N.W.; Roller, J.J.; Schultz, D.M.; Julien, J.T.; Weinmann, T.L.

    1987-08-01

    The tests described in this report are part of Phase 2 of the Electric Power Research Institute (EPRI) program. The overall objective of the EPRI program is to provide a test-verified analytical method of estimating capacities of concrete reactor containment buildings under internal overpressurization from postulated degraded core accidents. The Phase 2 testing included seven large-scale specimens representing structural elements from reinforced and prestressed concrete reactor containment buildings. Six of the seven test specimens were square wall elements. Of these six specimens, four were used for biaxial tension tests to determine strength, deformation, and leak-rate characteristics of full-scale wall elements representing prestressed concrete containment design. The remaining two square wall elements were used for thermal buckling tests to determine whether buckling of the steel liner plate would occur between anchorages when subjected to a sudden extreme temperature differential. The last of the seven test specimens for Phase 2 represented the region where the wall and the basemat intersect in a prestressed concrete containment building. A multi-directional loading scheme was used to produce high bending moments and shear in the wall/basemat junction region. The objective of this test was to determine if there is potential for liner plate tearing in the junction region. Results presented include observed behavior and extensive measurements of deformations and strains as a function of applied load. The data are being used to confirm analytical models for predicting strength and deformation of containment structures in a separate parallel analytical investigation sponsored by EPRI.

  6. Influence of the Density Structure of the Caribbean Plate Forearc on the Static Stress State and Asperity Distribution along the Costa Rican Seismogenic Zone

    NASA Astrophysics Data System (ADS)

    Lücke, O. H.; Gutknecht, B. D.

    2014-12-01

    Most of the forearc region along the Central American Subduction Zone shows a series of trench-parallel, positive gravity anomalies with corresponding gravity lows along the trench and toward the coast. These features extend from Guatemala to northern Nicaragua. However, the Costa Rican segment of the forearc does not follow this pattern. In this region, the along-trench gravity low is segmented, the coastal low is absent, and the forearc gravity high is located onshore at the Nicoya Peninsula which overlies the seismogenic zone. Geodetic and seismological studies along the Costa Rican Subduction Zone suggest the presence of coupled areas beneath the Nicoya Peninsula prior to the 2012, magnitude Mw 7.6 earthquake. These areas had previously been associated with asperities. Previous publications have proposed a mechanical model for the generation of asperities along the Chilean convergent margin based on the structure of the overriding plate above the seismogenic zone in which dense igneous bodies disturb the state of stress on the seismogenic zone and may influence seismogenic processes. In Costa Rica, surface geology and gravity data indicate the presence of dense basalt/gabbro crust overlying the seismogenic zone where the coupling is present. Bouguer anomaly values in this region reach up to 120×10-5 m/s2, which are the highest for Costa Rica. In this work, the state of stress on the Cocos-Caribbean plate interface is calculated based on the geometry and mass distribution of a 3D density model of the subduction zone as interpreted from gravity data from combined geopotential models. Results show a correlation between the coupled areas at the Nicoya Peninsula and the presence of stress anomalies on the plate interface. The stress anomalies are calculated for the normal component of the vertical stress on the seismogenic zone and are interpreted as being generated by the dense material which makes up the forearc in the area. The dense material of the Nicoya

  7. Technical Basis for Gas-Phase Vadose Zone Remediation Technologies at Hanford: A Review - 12186

    SciTech Connect

    Truex, M.J.; Oostrom, M.; Szecsody, J.E.; Strickland, C.E.; Chronister, G.B.; Benecke, M.W.

    2012-07-01

    In situ vadose zone remediation approaches are being evaluated as potential options to mitigate the transport of inorganic and radionuclide contaminants from the vadose zone to the groundwater. Some of the candidate approaches are based on changing the contaminant or subsurface conditions in a way that slows downward migration of the contaminants through the vadose zone using amendments delivered in the gas-phase. Two promising approaches that have undergone testing at Hanford include soil desiccation to address technetium-99 contamination and ammonia-induced sequestration of uranium. For soil desiccation, a dry gas is injected to desiccate a targeted portion of the subsurface and thereby decrease contaminant movement by removing moisture and decreasing the hydraulic conductivity of the desiccated zone. Ammonia-induced sequestration of uranium relies on changing the pore water chemistry, primarily through pH changes, to induce dissolution and precipitation processes that decrease the amount of mobile uranium in the vadose zone. (authors)

  8. Oblique collision and accretion of the Netherlands Leeward Antilles island arc: A structural analysis of the Caribbean-South American plate boundary zone

    NASA Astrophysics Data System (ADS)

    Beardsley, Amanda Gail

    2007-12-01

    The Netherlands Leeward Antilles volcanic island arc is an ideal natural laboratory to study the evolution of the Caribbean-South American plate boundary. The Leeward Antilles islands (Aruba, Curacao, and Bonaire) are located offshore western Venezuela, within the obliquely convergent diffuse plate boundary zone. Outcrop analysis, microthermometry, and 2D marine seismic reflection data provide evidence of three generations of regional deformation since the Late Cretaceous. Outcrop analysis of structural features, including faults, joints, and veins, characterizes the kinematic history of the islands. Fluid inclusion analysis of quartz and calcite veins coupled with apatite fission-track dating provides the island exhumation history. Finally, marine reflection seismic data processing and interpretation of newly acquired data elucidates offshore structures to integrate with our onshore results. The oldest regional deformation, resulting in both ductile (D1) and brittle (F 1) structures, is attributed to displacement partitioning along the arcuate Caribbean plate boundary. Associated crustal thinning initiated island exhumation, at a rate of 0.18 km/my, from a maximum burial depth of 6 km in the Late Cretaceous (˜89 Ma). Coeval with D1/F1 deformation and exhumation, stretching of the island arc resulted in extensive basin rifting that separated the island blocks. At ˜55 Ma, a change in the relative motion of the Caribbean plate altered plate boundary dynamics. Displacement along the right-lateral Caribbean transform fault and Oca - San Sebastian - El Pilar strike-slip fault system created a wrench tectonic regime within the diffuse plate boundary zone. A second generation of brittle structures (F2) developed while the islands were at a maximum burial depth of 2 km during the Paleocene/Eocene. Since ˜45 Ma, continued motion along the strike-slip fault systems and oblique plate convergence resulted in the youngest generation of structural features (F3). Regional

  9. Geometry of the Turkey-Arabia and Africa-Arabia plate boundaries in the latest Miocene to Mid-Pliocene: the role of the Malatya-Ovacık Fault Zone in eastern Turkey

    NASA Astrophysics Data System (ADS)

    Westaway, R.; Demir, T.; Seyrek, A.

    2007-11-01

    We suggest a working hypothesis for the geometry of the strike-slip faults that formed the boundaries between the Turkish, African and Arabian plates in the latest Miocene to Mid-Pliocene (LMMP), between ~7-6 Ma and ~3.5 Ma. This geometry differed significantly from the modern geometry; the northern Dead Sea Fault Zone (DSFZ) was located east of its present line and the TR-AR boundary was formed by the Malatya-Ovacık Fault Zone (MOFZ), located well north of the modern East Anatolian Fault Zone (EAFZ). The MOFZ is potentially the most problematic aspect of such a scheme, given the dramatically different interpretations of it that have been proposed. However, the presently-available evidence, albeit limited, is consistent with our proposed interpretation. Significant differences between the proposed LMMP fault geometry and the modern geometry include, first, the transtensional geometry of the MOFZ, the modern EAFZ being typically a left-lateral transform fault zone but with localized transpression. Second, the MOFZ slip rate was much lower than the ~9-10 mm a-1 EAFZ slip rate; it is estimated as ~2-3 mm a-1, having produced no more than ~8 km of slip during its approximately three million year long activity. Third, unlike at present, there was no throughgoing linkage of left-lateral faulting between the LMMP DSFZ and the MOFZ; instead, the DSFZ terminated northward, and the MOFZ terminated southward, in a zone of localised crustal shortening adjoining the suture of the former Neotethys Ocean in the Kahramanmaraç-Pazarcık region of SE Turkey. The different motion of the Turkish plate relative to Arabia, and, thus, relative to Eurasia, means that senses and rates of crustal deformation can be expected to have been different during the LMMP phase from at present, throughout the eastern Mediterranean region.

  10. What is responsible for development of the Asian-Pacific transition zone: The geodynamics of oceanic plates or the Asian continent?

    NASA Astrophysics Data System (ADS)

    Utkin, V. P.

    2016-03-01

    The main unusual feature of tectogenesis of the Asian-Pacific transition zone in the Mesozoic-Cenozoic consists in the formation of left-lateral strike-slip faults, which form the East Asian global shear zone with paragenesis of its constituent variously oriented fault systems. Paragenetic analysis has revealed that continental blocks of the Asian-Pacific transition zone were displaced along systems of transit left-lateral strike-slip faults of the East Asian global shear zone by hundreds of kilometers in the southerly to southwesterly direction due to tectonic activity of the Asian continent, which drifted southwestward. This process was accompanied by the formation of compression and extension structures. Otherwise, it is difficult to explain the structuring of the overhanging margin of the continent by subduction of oceanic lithospheric plates in the northerly to northwesterly direction opposite relative to the displacement of the continental crust as is usually thought.

  11. Plate tectonics conserves angular momentum

    NASA Astrophysics Data System (ADS)

    Bowin, C.

    2009-03-01

    A new combined understanding of plate tectonics, Earth internal structure, and the role of impulse in deformation of the Earth's crust is presented. Plate accelerations and decelerations have been revealed by iterative filtering of the quaternion history for the Euler poles that define absolute plate motion history for the past 68 million years, and provide an unprecedented precision for plate angular rotation variations with time at 2-million year intervals. Stage poles represent the angular rotation of a plate's motion between adjacent Euler poles, and from which the maximum velocity vector for a plate can be determined. The consistent maximum velocity variations, in turn, yield consistent estimates of plate accelerations and decelerations. The fact that the Pacific plate was shown to accelerate and decelerate, implied that conservation of plate tectonic angular momentum must be globally conserved, and that is confirmed by the results shown here (total angular momentum ~1.4 E+27 kgm2s-1). Accordingly, if a plate decelerates, other plates must increase their angular momentums to compensate. In addition, the azimuth of the maximum velocity vectors yields clues as to why the "bend" in the Emperor-Hawaiian seamount trend occurred near 46 Myr. This report summarizes processing results for 12 of the 14 major tectonic plates of the Earth (except for the Juan de Fuca and Philippine plates). Plate accelerations support the contention that plate tectonics is a product of torques that most likely are sustained by the sinking of positive density anomalies due to phase changes in subducted gabbroic lithosphere at depth in the upper lower mantle (above 1200 km depth). The tectonic plates are pulled along by the sinking of these positive mass anomalies, rather than moving at near constant velocity on the crests of convection cells driven by rising heat. These results imply that spreading centers are primarily passive reactive features, and fracture zones (and wedge-shaped sites

  12. SEARCHING FOR PLANETS IN HOLEY DEBRIS DISKS WITH THE APODIZING PHASE PLATE

    SciTech Connect

    Meshkat, Tiffany; Kenworthy, Matthew A.; Bailey, Vanessa P.; Su, Kate Y. L.; Hinz, Philip M.; Smith, Paul S.; Mamajek, Eric E.

    2015-02-10

    We present our first results from a high-contrast imaging search for planetary mass companions around stars with gapped debris disks, as inferred from the stars' bright infrared excesses. For the six considered stars, we model the disks' unresolved infrared spectral energy distributions in order to derive the temperature and location of the disk components. With VLT/NaCo Apodizing Phase Plate coronagraphic L'-band imaging, we search for planetary mass companions that may be sculpting the disks. We detect neither disks nor companions in this sample, confirmed by comparing plausible point sources with archival data. In order to calculate our mass sensitivity limit, we revisit the stellar age estimates. One target, HD 17848, at 540 ± 100 Myr old is significantly older than previously estimated. We then discuss our high-contrast imaging results with respect to the disk properties.

  13. A novel silver-coated solid-phase microextraction metal fiber based on electroless plating technique.

    PubMed

    Feng, Juanjuan; Sun, Min; Li, Jubai; Liu, Xia; Jiang, Shengxiang

    2011-09-01

    A novel silver-coated solid-phase microextraction fiber was prepared based on electroless plating technique. Good extraction performance of the fiber for model compounds including phthalate esters (dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate and diallyl phthalate) and polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, fluoranthene) in aqueous solution was obtained. Under the optimized conditions (extraction temperature, extraction time, ionic strength and desorption temperature), the proposed SPME-GC method showed wide linear ranges with correlation coefficients (R(2)) ranging from 0.9745 to 0.9984. The limits of detection were at the range of 0.02 to 0.1 μg L(-1). Single fiber repeatability and fiber-to-fiber reproducibility as well as stability to acid, alkali and high temperature were studied and the results were all satisfactory. The method was applied successfully to the aqueous extracts of disposable paper cup and instant noodle barrel. Several kinds of analytes were detected and quantified. PMID:21801885

  14. GROWTH PLATE ABNORMALITIES IN PEDIATRIC CANCER PATIENTS UNDERGOING PHASE 1 ANTI-ANGIOGENIC THERAPY: A REPORT FROM THE CHILDREN’S ONCOLOGY GROUP PHASE I CONSORTIUM

    PubMed Central

    Voss, Stephan D.; Glade-Bender, Julia; Spunt, Sheri L.; DuBois, Steven G.; Widemann, Brigitte C.; Park, Julie R.; Leary, Sarah E. S.; Nelson, Marvin D.; Adamson, Peter C.; Blaney, Susan M.; Weigel, Brenda

    2014-01-01

    Purpose Pre-clinical studies suggest that anti-angiogenic agents may be toxic to the developing growth plate. The purpose of this study was to evaluate the incidence of growth plate abnormalities in children with refractory cancer undergoing anti-angiogenic therapy. Materials and methods Targeted radiographic studies from 53 subjects enrolled on six separate Children’s Oncology Group Phase 1 and Pilot Consortium clinical trials evaluating new anti-cancer agents agents interfering with angiogenesis were reviewed. Subjects received tyrosine kinase inhibitors with anti-angiogenic effects (n=35), monoclonal antibodies targeting VEGF (n=13), or angiopoietin (n=5). Radiographs of their distal femur/proximal tibia were obtained at baseline. Follow-up radiographs were obtained after odd-numbered treatment cycles in patients with open growth plates who did not experience disease progression prior to cycle 3. Results Baseline and follow-up growth plate radiographs were acquired in 48/53 (90%) of patients. Five patients (9.4%), all of whom received a specific VEGF/VEGFR blocking agent [sunitinib (n=1) or pazopanib (n=4)], had growth plate abnormalities. Four patients had growth plate widening that was apparent on at least two successive radiographs, but was not confirmed by MRI. The fifth patient had progressive growth plate widening and evidence of physeal cartilage hypertrophy on MRI. Subsequent off treatment radiographs showed that the growth plate changes were reversible. Conclusion Growth plate abnormalities occur in a small, but relevant number of patients undergoing anti-angiogenic therapy. These results support the need for growth plate monitoring in children with open growth plates who are receiving anti-angiogenic therapy, and for improved methods to assess toxicity of anti-angiogenic agents to the developing skeleton. PMID:25257751

  15. Geometry of Pacific plate in Kuril-Japan trench zones estimated from earthquake distribution using LT-OBS network and seismic structures by marine surveys

    NASA Astrophysics Data System (ADS)

    Shinohara, M.; Yamada, T.; Kuwano, A.; Nakahigashi, K.; Machida, Y.; Mochizuki, K.; Kanazawa, T.; Takanami, T.; Hino, R.

    2009-12-01

    The seismicity of the Japan arc region is as high as that observed in other areas of subduction of oceanic plates. The Japan Trench and Kuril Trench are plate convergent zones where the Pacific Plate is subducting below the Japan island. In addition, the trench is crooked off Erimo cape, Hokkaido. It is considered the bend of the trench causes complex shape of the plate boundary. There is a possibility that an asperity of a large earthquake is controlled by a shape of a plate boundary. Associated with the plate convergence, many earthquakes occur beneath landward slopes of the Japan Trench and the Kuril Trench. Such earthquakes are considered to occur mainly at plate boundary between the Pacific plate and the landward plate in landward slope of the Kuril trench and the Japan trench. Therefore, to obtain precise hypocenter distribution of earthquakes occurring in the regions is essential to estimate geometry of the plate boundary. For several years, we performed dense seafloor earthquake observation using Long-Term Ocean Bottom Seismometers (LT-OBSs) in this region, including the aftershock observation of the 2003 Tokachi-oki earthquakes which is a large interplate earthquake around the Japan island arc. In the region off Nemuro, dense seafloor observation was carried out from 2005 to 2006 for one year using LT-OBSs. In the region off Aomori, we performed the same type of a seafloor earthquake observation from 2004 to 2007 for two years in total. Ninety-two LT-OBSs were used for the observations, and an interval of the LT-OBS is approximately 20 km. The LT-OBS has three-component seismometer with a natural period of 1 Hz, and reaches a recoding period of 1 year. As a result, we obtained the precise hypocenter distribution from the region off Nemuro to the region off Aomori, and the hypocenter distribution of huge number of earthquakes enables us to estimate the geometry of the plate boundary. Additionally, seismic surveys using OBSs and controlled source were

  16. The Ionian and Alfeo-Etna fault zones: New segments of an evolving plate boundary in the central Mediterranean Sea?

    NASA Astrophysics Data System (ADS)

    Polonia, A.; Torelli, L.; Artoni, A.; Carlini, M.; Faccenna, C.; Ferranti, L.; Gasperini, L.; Govers, R.; Klaeschen, D.; Monaco, C.; Neri, G.; Nijholt, N.; Orecchio, B.; Wortel, R.

    2016-04-01

    The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW-SSE transtensive fault system connecting the Alfeo seamount and the Etna volcano (Alfeo-Etna Fault, AEF). A second, NW-SE crustal discontinuity, the Ionian Fault (IF), separates two lobes of the CA subduction complex (Western and Eastern Lobes) and impinges on the Sicilian coasts south of the Messina Straits. Analysis of multichannel seismic reflection profiles shows that: 1) the IF and the AEF are transfer crustal tectonic features bounding a complex deformation zone, which produces the downthrown of the Western lobe along a set of transtensive fault strands; 2) during Pleistocene times, transtensive faulting reactivated structural boundaries inherited from the Mesozoic Tethyan domain which acted as thrust faults during the Messinian and Pliocene; and 3) the IF and the AEF, and locally the Malta escarpment, accommodate a recent tectonic event coeval and possibly linked to the Mt. Etna formation. Regional geodynamic models show that, whereas AEF and IF are neighboring fault systems, their individual roles are different. Faulting primarily resulting from the ESE retreat of the Ionian slab is expressed in the northwestern part of the IF. The AEF, on the other hand, is part of the overall dextral shear deformation, resulting from differences in Africa-Eurasia motion between the western and eastern sectors of the Tyrrhenian margin of northern Sicily, and accommodating diverging motions in the adjacent compartments, which results in rifting processes within the Western Lobe of the Calabrian Arc accretionary wedge. As such, it is primarily associated with Africa-Eurasia relative motion.

  17. Fault Population Analyses in the Eastern California Shear Zone: Insights into the Development of Young, Actively Evolving Plate Boundary Structures

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Dawers, N. H.; Amer, R. M.

    2014-12-01

    Relationships between cumulative fault displacement, slip rate and length, along with fault population statistics are analyzed for faults located within the Eastern California Shear Zone (ECSZ), focusing on areas north of the Garlock fault. Here many faults are geologically young and in an early stage of evolution, while many older and larger faults are also still active. We analyze scaling relationships for both strike-slip and normal faults in order to determine whether the two fault populations share the same properties or not. Cumulative displacement, slip rate and length data are collected from published maps and literature sources. The dataset spans fault lengths from tens of meters to hundreds of kilometers. Results of fault scaling analyses indicate that displacement has a linear relationship with fault length for normal faults in this area over the entire length span, whereas strike-slip faults do not have a clear displacement-length scaling relation. For a given length, the subset of strike-slip faults typically exhibits a much larger displacement than that for the normal faults. The slip rate versus length trends are similar but are considerably more scattered. In addition, we define a subpopulation of normal faults that are kinematically related to the right-lateral strike-slip faults; these have a maximum length set by the spacing between the right-lateral faults. Fault size-frequency distributions also indicate differences between the normal and strike-slip fault populations. Overall, the normal faults have higher ratios of cumulative number to fault length than the strike-slip population does, which we relate to different patterns of localization of faulting. We interpret these trends as reflecting different tectonic histories, with the majority of normal faults being intraplate faults associated with Basin and Range extension and the strike-slip faults being kinematically connected with plate boundary.

  18. Effect of Mg Content on the Microstructure and Toughness of Heat-Affected Zone of Steel Plate after High Heat Input Welding

    NASA Astrophysics Data System (ADS)

    Xu, Long-Yun; Yang, Jian; Wang, Rui-Zhi; Wang, Yu-Nan; Wang, Wan-Lin

    2016-05-01

    The effect of Mg content on the microstructure and toughness of the heat-affected zone (HAZ) of steel plates after high heat input welding was investigated by means of welding thermal simulation test and in situ observation through high-temperature laser scanning confocal microscopy. It was found that with the increase of Mg content in the steel, the former austenite grain sizes were greatly decreased and the mainly microstructural constituents in HAZ were changed from the brittle constituents of Widmanstätten ferrite, ferrite side plate and upper bainite to the ductile constituents of intragranular acicular ferrite and polygonal ferrite. The proportion of grain boundary ferrite was decreased greatly with the further addition of Mg from 27 to 99 ppm. As a result, the HAZ toughness after welding with heat input of 400 kJ cm-1 is increased with increasing Mg content in the steel plate.

  19. Effect of Mg Content on the Microstructure and Toughness of Heat-Affected Zone of Steel Plate after High Heat Input Welding

    NASA Astrophysics Data System (ADS)

    Xu, Long-Yun; Yang, Jian; Wang, Rui-Zhi; Wang, Yu-Nan; Wang, Wan-Lin

    2016-07-01

    The effect of Mg content on the microstructure and toughness of the heat-affected zone (HAZ) of steel plates after high heat input welding was investigated by means of welding thermal simulation test and in situ observation through high-temperature laser scanning confocal microscopy. It was found that with the increase of Mg content in the steel, the former austenite grain sizes were greatly decreased and the mainly microstructural constituents in HAZ were changed from the brittle constituents of Widmanstätten ferrite, ferrite side plate and upper bainite to the ductile constituents of intragranular acicular ferrite and polygonal ferrite. The proportion of grain boundary ferrite was decreased greatly with the further addition of Mg from 27 to 99 ppm. As a result, the HAZ toughness after welding with heat input of 400 kJ cm-1 is increased with increasing Mg content in the steel plate.

  20. End plate assembly having a two-phase fluid-filled bladder and method for compressing a fuel cell stack

    DOEpatents

    Carlstrom, Jr., Charles M.

    2001-01-01

    An end plate assembly is disclosed for use in a fuel cell assembly in which the end plate assembly includes a housing having a cavity, and a bladder receivable in the cavity and engageable with the fuel cell stack. The bladder includes a two-phase fluid having a liquid portion and a vapor portion. Desirably, the two-phase fluid has a vapor pressure between about 100 psi and about 600 psi at a temperature between about 70 degrees C. to about 110 degrees C.

  1. Impact of The N - S Fracture Zone Along The Indo-Australia Plate Analyzed from Local Seismic Data In The Western Offshore of Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Haridhi, H. A.; Klingelhoefer, F.; Huang, B. S.; Lee, C. S.

    2015-12-01

    Large subduction earthquake have repeatedly occurred along the Sumatra and Andaman subduction zones where the Indo-Australia plate is subducting beneath the Eurasian plate. We have analyzed earthquake data from local seismic network along the Sumatra region that provided by the Meteorology Climatology Geophysical Agencies of Indonesia (MCGAI), giving a reliable P-wave velocity model by using joint inversion of picked P-wave travel time using VELEST and a re-scanned single channel seismic reflection of Sumatra cruise I and II. As much as 1,503 events are being analyzed, that is from two years and three months of data recording (2009/04 - 2011/07). The VELEST and DD technique are used to relocate all events by forcing the obtained velocity model. It is found that the surface deformation and earthquake cluster are strongly influenced by the impact of an N - S subparalel fracture zone along the Indo-Australia plate. This also explains the seismic gaps along the Sumatra and Andaman subduction zones. So far, the intriguing seismogenic behaviour and forearc structure are not well explained by the existing models. Therefore, the planned IODP Expedition 362 is trying to ground truth the scientific questions. The aftershock earthquake data are huge, but they will provide a gateway to help the understanding of this shallow megathrust slip and reduce its devastated harzards.

  2. Formulation and Application of a Physically-Based Rupture Probability Model for Large Earthquakes on Subduction Zones: A Case Study of Earthquakes on Nazca Plate

    NASA Astrophysics Data System (ADS)

    Mahdyiar, M.; Galgana, G.; Shen-Tu, B.; Klein, E.; Pontbriand, C. W.

    2014-12-01

    -based rupture probability models for large earthquakes on subduction zones that is consistent with their true locking state and earthquake history. We will present the formulation of the proposed model and its application to the Nazca plate subduction zone.

  3. An inverted double seismic zone in chile: evidence of phase transformation in the subducted slab.

    PubMed

    Comte, D; Suárez, G

    1994-01-14

    Data from two microseismic field experiments in northern Chile revealed an elongated cluster of earthquakes in the subducted Nazca plate at a depth of about 100 kilometers in which down-dip tensional events were consistently shallower than a family of compressional earthquakes. This double seismic zone shows a distribution of stresses of opposite polarity relative to that observed in other double seismic zones in the world. The distribution of stresses in northern Chile supports the notion that at depths of between 90 to 150 kilometers, the basalt to eclogite transformation of the subducting oceanic crust induces tensional deformation in the upper part of the subducted slab and compressional deformation in the underlying mantle. PMID:17839180

  4. Modeled Temperatures and Fluid Source Distributions for the Mexico Subduction Zone: Effects of Hydrothermal Cooling and Implications for Plate Boundary Seismic Processes

    NASA Astrophysics Data System (ADS)

    Perry, M. R.; Spinelli, G. A.; Wada, I.

    2014-12-01

    In subduction zones, spatial variations in pore fluid pressure are hypothesized to control the distribution and nature of slip behavior (e.g., "normal" earthquakes, slow slip events, non-volcanic tremor, very low frequency earthquakes) on the plate boundary fault. A primary control on the pore fluid pressure distribution in subduction zones is the distribution of fluid release from hydrous minerals in the subducting sediment and rock. The distributions of these diagenetic and metamorphic fluid sources are controlled by the pressure-temperature paths that the subducting material follows. Thus, constraining subduction zone thermal structure is required to inform conceptual models of seismic behavior. Here, we present results of thermal models for the Mexico subduction zone, a system that has received recent attention due to observations of slow-slip events and non-volcanic tremor. We model temperatures in five margin-perpendicular transects from 96 ˚W to 104 ˚W. In each transect, we examine the potential thermal effects of vigorous fluid circulation in a high permeability aquifer within the basaltic basement of the oceanic crust. In the transect at 100˚W, hydrothermal circulation cools the subducting material by up to 140 ˚C, shifting peak slab dehydration landward by ~100 km relative to previous estimates from models that do not include the effects of fluid circulation. The age of the subducting plate in the trench increases from ~3 Ma at 104 ˚W to ~18 Ma at 96 ˚W; hydrothermal circulation redistributes the most heat (and cools the system the most) where the subducting plate is youngest. For systems with <20 Ma subducting lithosphere, hydrothermal circulation in oceanic crust should be considered in estimating subduction zone temperatures and fluid source distributions.

  5. Phased annular array transducers for omnidirectional guided wave mode control in isotropic plate like structures

    NASA Astrophysics Data System (ADS)

    Koduru, Jaya P.; Momeni, Sepandarmaz; Rose, Joseph L.

    2013-12-01

    Ultrasonic guided waves are fast emerging as a reliable tool for continuous structural health monitoring. Their multi-modal nature along with their long range propagation characteristics offer several possibilities for interrogating structures. Transducers commonly used to generate guided waves in structures excite multiple modes at any frequency; their complex scattering and reflection from defects and boundaries often complicates the extraction of useful information. Often it is desirable to control the guided wave modes propagating in a structure to take advantage of their unique properties for different applications. Earlier attempts at guided wave mode control involved developing fixed wavelength linear and annular array transducers. Their only disadvantage is that the transducer is limited to a particular wavelength and a change in wavelength necessitates a change in the transducer. In this paper, we propose the development of an annular array transducer that can generate mode controlled omnidirectional guided waves by independently controlling the amplitude and phase of the array elements. A simplified actuator model that approximates the transducer loading on the structure to a constant pressure load under the array elements is assumed and an optimization problem is set up to compute the excitation voltage and phase of the elements. A five element annular array transducer is designed utilizing 1-3 type piezocomposite materials. The theoretical computations are experimentally verified on an aluminum plate like structure by exciting A0 and S0 guided wave modes.

  6. Neutron Diffraction Residual Strain Tensor Measurements Within The Phase IA Weld Mock-up Plate P-5

    SciTech Connect

    Hubbard, Camden R

    2011-09-01

    Oak Ridge National Laboratory (ORNL) has worked with NRC and EPRI to apply neutron and X-ray diffraction methods to characterize the residual stresses in a number of dissimilar metal weld mockups and samples. The design of the Phase IA specimens aimed to enable stress measurements by several methods and computational modeling of the weld residual stresses. The partial groove in the 304L stainless steel plate was filled with weld beads of Alloy 82. A summary of the weld conditions for each plate is provided in Table 1. The plates were constrained along the long edges during and after welding by bolts with spring-loaded washers attached to the 1-inch thick Al backing plate. The purpose was to avoid stress relief due to bending of the welded stainless steel plate. The neutron diffraction method was one of the methods selected by EPRI for non-destructive through thickness strain and stress measurement. Four different plates (P-3 to P-6) were studied by neutron diffraction strain mapping, representing four different welding conditions. Through thickness neutron diffraction strain mappings at NRSF2 for the four plates and associated strain-free d-zero specimens involved measurement along seven lines across the weld and at six to seven depths. The mountings of each plate for neutron diffraction measurements were such that the diffraction vector was parallel to each of the three primary orthogonal directions of the plate: two in-plane directions, longitudinal and transverse, and the direction normal to the plate (shown in left figure within Table 1). From the three orthogonal strains for each location, the residual stresses along the three plate directions were calculated. The principal axes of the strain and stress tensors, however, need not necessarily align with the plate coordinate system. To explore this, plate P-5 was selected for examination of the possibility that the principal axes of strain are not along the sample coordinate system axes. If adequate data could

  7. Subduction zone tectonic studies to develop concepts for the occurrence of sediment subduction (Phase I). Final technical report

    SciTech Connect

    Hilde, T.W.C.

    1984-08-01

    The objective was to determine the fate of sediments at convergent lithospheric plate boundaries. The study focuses on the structures of the Circum-Pacific trenches and shallow portions of the associated subduction zones. Sediment distribution and the nature of sediment deformation was defined through the various stages of plate convergence to determine if the sediments are subducted or accreted. The controlling factors for sediment subduction and/or accretion were determined. 50 figs. (ACR)

  8. Low Intensity Characteristic of Plate-Boundary S-S Reflections Within a Region of Strong Plate-Boundary P-P Reflections and low Seismicity Along the Japan Trench Subduction Zone

    NASA Astrophysics Data System (ADS)

    Mochizuki, K.; Kasahara, J.; Hino, R.; Nishino, M.; Yamada, T.; Shinohara, M.; Kanazawa, T.

    2003-12-01

    It has been pointed out that the epicenters of the microearthquakes along the forearc slope of the Japan Trench are not uniformly distributed but clustered in seismically active zones that are oriented perpendicular to the trench axis. One of the clear seismic-aseismic boundaries of such seismic clusters can be identified in latitude 39° N. A seismic survey was conducted in 1996 with one profile running across the boundary and parallel to the trench axis, and a P-wave velocity structure model was obtained by travel-time inversion (Fujie, 1999). A strong anti-correlation between the seismicity and the intensity of the plate-boundary P-P reflected waves was found: strong plate-boundary P-P reflected waves were observed in a region where seismicity is quite low, and vice versa (Fujie et al., 2002). They discussed that a thin layer of low P-wave velocities (3~4 km/s) with its thickness up to a few hundred meters along the plate boundary could explain the intensity of the reflections. Results of finite-difference waveform calculations support this estimation (Moghaddam, 2002). Another seismic survey was carried out in 2001 with 7 trench-parallel profiles in the same region as the 1996 survey in order to map and verify the strong anti-correlation. The strong anti-correlation was observed over the seismic-aseismic boundary region, and it was inferred that a thin layer with low P-wave velocities along the plate boundary exists beneath the aseismic zone in the region. Understanding the characteristics of plate-boundary S-S reflections in addition to those of P-P reflections would greatly help put better constraints on the physical properties along the plate boundary. Substantial P-to-S conversion at the base of the sedimentary layers was observed. S-wave velocities, especially those of the sedimentary layers, should be precisely determined in order to have good estimates of the arrival times of the plate-boundary S-S reflected waves. The S-wave velocities of the

  9. Numerical modeling of the evolution of two-phase zone under fissured caprock

    SciTech Connect

    Yano, Y.; Ishido, T.

    1993-01-28

    A vapor-dominated two-phase zone would be formed in a geothermal reservoir under fissured caprock, if the permeability of the fissure is much smaller than a critical permeability which is estimated by an energy balance. If the permeability of the fissure is large, then the rule of minimum mass input would be applied.

  10. Development of a Hydrologic Characterization Technology for Fault Zones Phase II 2nd Report

    SciTech Connect

    Karasaki, Kenzi; Doughty, Christine; Gasperikova, Erika; Peterson, John; Conrad, Mark; Cook, Paul; Tiemi, Onishi

    2011-03-31

    This is the 2nd report on the three-year program of the 2nd phase of the NUMO-LBNL collaborative project: Development of Hydrologic Characterization Technology for Fault Zones under NUMO-DOE/LBNL collaboration agreement. As such, this report is a compendium of the results by Kiho et al. (2011) and those by LBNL.

  11. Piezoelectric phased array acousto-ultrasonic interrogation of damage in thin plates

    NASA Astrophysics Data System (ADS)

    Purekar, Ashish S.

    Structural Health Monitoring (SHM) and Condition Based Maintenance (CBM) systems can provide substantial benefits for aging aerospace systems as well as newer systems still in the design process. In aging aerospace systems, a retrofitted SHM system would alert users of incipient damage preventing catastrophic failure. For newer systems, incorporating a SHM approach and using CBM techniques can reduce life-cycle costs. Central to such SHM and CBM systems is the ability to detect damage in a structure. Traditional approaches to damage detection in structures involve one of two methods. In the modal dynamics approach, the natural frequencies and modeshapes of a structure shift when damage occurs. The location, type, and amount of damage is determined by the shifts in the modal properties due to damage. Alternately, in an Ultrasonics approach, the structure is scanned with a specialized transducer which induces high frequency vibrations in the structure. Damage in the structure is inferred when these vibrations are altered. In the same vein as Ultrasonics, Acoustic Emission based methods listen for energy release in the structure upon defect growth. All of these techniques have limitations which hinder their usage in a practical system. This thesis attempts to develop a methodology with the benefits of the modal approach as well as the Ultrasonics/Acoustic Emission approach. The methodology is commonly referred to as an Acousto-Ultrasonic technique for damage detection. The structural dynamics of plate structures is described as wavelike in nature where the plate is a medium for wave propagation. For thin plates, bulk wave propagation is described using Lamb wave modes. The two fundamental modes of wave propagation are the in-plane acoustic mode and the transverse bending mode. The interaction of these waves with a discontinuity or damaged region changes the way the waves propagate. Part of the incident wavefront is reflected back while the rest is transmitted through

  12. Surface wave phase velocities from 2-D surface wave tomography studies in the Anatolian plate

    NASA Astrophysics Data System (ADS)

    Arif Kutlu, Yusuf; Erduran, Murat; Çakır, Özcan; Vinnik, Lev; Kosarev, Grigoriy; Oreshin, Sergey

    2014-05-01

    We study the Rayleigh and Love surface wave fundamental mode propagation beneath the Anatolian plate. To examine the inter-station phase velocities a two-station method is used along with the Multiple Filter Technique (MFT) in the Computer Programs in Seismology (Herrmann and Ammon, 2004). The near-station waveform is deconvolved from the far-station waveform removing the propagation effects between the source and the station. This method requires that the near and far stations are aligned with the epicentre on a great circle path. The azimuthal difference of the earthquake to the two-stations and the azimuthal difference between the earthquake and the station are restricted to be smaller than 5o. We selected 3378 teleseismic events (Mw >= 5.7) recorded by 394 broadband local stations with high signal-to-noise ratio within the years 1999-2013. Corrected for the instrument response suitable seismogram pairs are analyzed with the two-station method yielding a collection of phase velocity curves in various period ranges (mainly in the range 25-185 sec). Diffraction from lateral heterogeneities, multipathing, interference of Rayleigh and Love waves can alter the dispersion measurements. In order to obtain quality measurements, we select only smooth portions of the phase velocity curves, remove outliers and average over many measurements. We discard these average phase velocity curves suspected of suffering from phase wrapping errors by comparing them with a reference Earth model (IASP91 by Kennett and Engdahl, 1991). The outlined analysis procedure yields 3035 Rayleigh and 1637 Love individual phase velocity curves. To obtain Rayleigh and Love wave travel times for a given region we performed 2-D tomographic inversion for which the Fast Marching Surface Tomography (FMST) code developed by N. Rawlinson at the Australian National University was utilized. This software package is based on the multistage fast marching method by Rawlinson and Sambridge (2004a, 2004b). The

  13. Crustal Structure of the Caribbean-South American Diffuse Plate Boundary: Subduction Zone Migration and Polarity Reversal Along BOLIVAR Profile 64W

    NASA Astrophysics Data System (ADS)

    Clark, S. A.; Levander, A.; Magnani, M.; Zelt, C. A.; Sawyer, D. S.; Ave Lallemant, H. G.

    2005-12-01

    The BOLIVAR (Broadband Ocean-Land Investigation of Venezuela and the Antilles arc Region) project is an NSF funded, collaborative seismic experiment in the southeast Caribbean region. The purpose of the project is to understand the diffuse plate boundary created by the oblique collision between the Caribbean and South American plates. Profile 64W of the BOLIVAR experiment, a 450 km-long, N-S transect onshore and offshore Venezuela located at ~64°W longitude, images the deep crustal structures formed by this collision. The active source components of profile 64W include 300 km of MCS reflection data, 33 coincident OBSs, and 344 land seismic stations which recorded 7500 offshore airgun shots and 2 explosive land shots. Results from the reflection and refraction seismic data along 64W show complex crustal structure across the entire span of the diffuse plate boundary. The onshore portion of 64W crosses the fold and thrust belt of the Serrania del Interior, which formed at ~16 Ma by collision of the Caribbean forearc with the northern South American passive margin. Underlying the Serrania del Interior is a south-vergent, remnant Lesser Antillean subduction zone. As this Lesser Antilles subduction impinged on continental crust, it caused a polarity reversal and jump offshore to the north. Convergence was initially localized in the closure and inversion of the Grenada Basin. However, subduction could not develop because of the ~20-km-thick crust of the Aves Ridge; instead, north-vergent subduction initiated further to the north, where ~12-km-thick Caribbean oceanic crust of the Venezuela Basin began to subduct beneath the Aves Ridge in the Pliocene (~4 Ma) and appears to continue subducting today. Between the remnant subduction zone and the modern one, the El Pilar and Coche dextral strike-slip faults accommodate most of the transform motion of the plate boundary. From the Serrania del Interior to the Aves Ridge, ~260 km of accreted orogenic float comprises the diffuse

  14. The Teisseyre-Tornquist Zone - early Palaeozoic strike-slip plate boundary or Ediacaran rifted margin of Baltica?

    NASA Astrophysics Data System (ADS)

    Mazur, Stanislaw; Krzywiec, Piotr; Malinowski, Michal; Lewandowski, Marek; Buffenmeyer, Vinton; Green, Christopher

    2016-04-01

    The Teisseyre-Tornquist Zone (TTZ) is the longest European tectonic and geophysical lineament extending from the Baltic Sea in the northwest to the Black Sea in the southeast. This tectonic feature defines a transition between the thick crust of the East European Craton (EEC) and the thinner crust of the Palaeozoic Platform to the southwest. Being a profound zone of crustal and lithospheric thickness perturbation, the TTZ has usually been considered a Caledonian tectonic suture formed due to the closure of the Tornquist Ocean. The suture was hypothesised to originate from the collision between Baltica and Avalonia or large-scale strike-slip displacement along strike of the Caledonian Orogen. However, some minority views postulated the continuation of Baltica crystalline basement farther to the southwest up to the Elbe Lineament and the margin of the Variscan Belt. We studied the ION Geophysical PolandSPAN survey that consists of 10 regional, seismic depth profiles covering the SW margin of the EEC and the TTZ in Poland. Since the PolandSPAN profiles image to ~30 km depth their interpretation was integrated with the potential fields data and earlier results of refraction sounding to better image the deep structure of the TTZ. Our data show that the NW and central sections of the TTZ correspond, at the Moho level, to a relatively narrow crustal keel and a significant Moho step at the transition from the EEC to the Palaeozoic Platform. However, top of basement above the TTZ is smooth and moderately sloping towards the southwest. In the central part of the TTZ, top of Precambrian is covered by undisturbed lower Palaeozoic sediments. In contrast, the lower Palaeozoic sediments are involved in a latest Silurian, thin-skinned fold-and-thrust belt along the NW section of the TTZ, where the sharply defined Caledonian Deformation Front adjoins a rigid basement buttress above the TTZ. Finally, the crustal keel is mostly missing from the SE section of the TTZ. Instead, this

  15. Geometry of the Turkey-Arabia and Africa-Arabia plate boundaries in the latest Miocene to Mid-Pliocene: the role of the Malatya-Ovacık Fault Zone in eastern Turkey

    NASA Astrophysics Data System (ADS)

    Westaway, R.; Demir, T.; Seyrek, A.

    2008-08-01

    We suggest a working hypothesis for the geometry of the strike-slip faults that formed the boundaries between the Turkish, African and Arabian plates in the latest Miocene to Mid-Pliocene (LMMP), between ~7 6 Ma and ~3.5 Ma. This geometry differed significantly from the modern geometry; the northern Dead Sea Fault Zone (DSFZ) was located east of its present line and the TR-AR boundary was formed by the Malatya-Ovacık Fault Zone (MOFZ), located well north of the modern East Anatolian Fault Zone (EAFZ). The MOFZ is potentially the most problematic aspect of such a scheme, given the dramatically different interpretations of it that have been proposed. However, the presently-available evidence, albeit limited, is consistent with our proposed interpretation. Significant differences between the proposed LMMP fault geometry and the modern geometry include, first, the transtensional geometry of the MOFZ, the modern EAFZ being typically a left-lateral transform fault zone but with localized transpression. Second, the MOFZ slip rate was much lower than the ~9 10 mm a-1 EAFZ slip rate; it is estimated as ~2 3 mm a-1, having produced no more than ~8 km of slip during its approximately three million year long activity. The Euler vector is tentatively inferred to have involved relative rotation between the Turkish and Arabian Plates at ~0.85±0.15° Ma-1 about a pole at ~37.75±0.15° N, ~38.8±0.3° E. Third, unlike at present, there was no throughgoing linkage of left-lateral faulting between the LMMP DSFZ and the MOFZ; instead, the DSFZ terminated northward, and the MOFZ terminated southward, in a zone of localised crustal shortening adjoining the suture of the former Neotethys Ocean in the Kahramanmaraş-Pazarcık region of SE Turkey. The different motion of the Turkish plate relative to Arabia, and, thus, relative to Eurasia, means that senses and rates of crustal deformation can be expected to have been different during the LMMP phase from at present, throughout the

  16. Spiral phase plates with radial discontinuities for the generation of multiring orbital angular momentum beams: fabrication, characterization, and application

    NASA Astrophysics Data System (ADS)

    Ruffato, Gianluca; Massari, Michele; Carli, Marta; Romanato, Filippo

    2015-11-01

    A design of spiral phase plates for the generation of multiring beams carrying orbital angular momentum (OAM) is presented. Besides the usual helical profile, these phase plates present radial π-discontinuities in correspondence of the zeros of the associated Laguerre polynomials. Samples were fabricated by electron beam lithography over glass substrates coated with a polymethylmethacrylate resist layer. The optical response was analyzed and the purity of the generated beams was investigated in terms of Laguerre-Gaussian modes contributions. The far-field intensity pattern was compared with theoretical models and numerical simulations, while the expected phase features were confirmed by interferometric analysis with a Mach-Zehnder setup. The high quality of the output beams confirms the applicability of these phase plates for the generation of high-order OAM beams with nonzero radial index. An application consisting of the design of computer-generated holograms encoding information for light beams carrying phase singularities is presented and described. A numerical code based on an iterative Fourier transform algorithm has been developed for the computation of phase-only diffractive optical element for illumination under OAM beams. Numerical analysis and preliminary experimental results confirm the applicability of these devices as high-security optical elements for anticounterfeiting applications.

  17. Role of the offshore Pedro Banks left-lateral strike-slip fault zone in the plate tectonic evolution of the northern Caribbean

    NASA Astrophysics Data System (ADS)

    Ott, B.; Mann, P.; Saunders, M.

    2013-12-01

    Previous workers, mainly mapping onland active faults on Caribbean islands, defined the northern Caribbean plate boundary zone as a 200-km-wide bounded by two active and parallel strike-slip faults: the Oriente fault along the northern edge of the Cayman trough with a GPS rate of 14 mm/yr, and and the Enriquillo-Plaintain Garden fault zone (EPGFZ) with a rate of 5-7 mm/yr. In this study we use 5,000 km of industry and academic data from the Nicaraguan Rise south and southwest of the EPGFZ in the maritime areas of Jamaica, Honduras, and Colombia to define an offshore, 700-km-long, active, left-lateral strike-slip fault in what has previously been considered the stable interior of the Caribbean plate as determined from plate-wide GPS studies. The fault was named by previous workers as the Pedro Banks fault zone because a 100-km-long segment of the fault forms an escarpment along the Pedro carbonate bank of the Nicaraguan Rise. Two fault segments of the PBFZ are defined: the 400-km-long eastern segment that exhibits large negative flower structures 10-50 km in width, with faults segments rupturing the sea floor as defined by high resolution 2D seismic data, and a 300-km-long western segment that is defined by a narrow zone of anomalous seismicity first observed by previous workers. The western end of the PBFZ terminates on a Quaternary rift structure, the San Andres rift, associated with Plio-Pleistocene volcanism and thickening trends indicating initial rifting in the Late Miocene. The southern end of the San Andreas rift terminates on the western Hess fault which also exhibits active strands consistent with left-lateral, strike-slip faults. The total length of the PBFZ-San Andres rift-Southern Hess escarpment fault is 1,200 km and traverses the entire western end of the Caribbean plate. Our interpretation is similar to previous models that have proposed the "stable" western Caribbean plate is broken by this fault whose rate of displacement is less than the threshold

  18. An estimate of tidal and non-tidal modulations of plate subduction speed in the transition zone in the Tokai district

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshiyuki; Yabe, Suguru; Ide, Satoshi

    2015-09-01

    Non-volcanic tremors and slow slip events in subduction zones have been found to be triggered by small external stress disturbances, as demonstrated by the synchronization of temporal variations in tremor rate with diurnal and semi-diurnal tides. Therefore, long-term variations in tremor rate might be predicted by amplitude modulations of diurnal and semi-diurnal tides at decadal time scales. Given that tremors and slow slips are shear slip on the plate boundary, their long-term variations must be associated with fluctuations in plate subduction speed below the seismogenic zone. In previous work, we showed a good correlation between long-term seismicity and empirically calculated tremor rate based on observed tidal levels in the Nankai region, western Japan. Here, we present an improved method of modeling long-term slip rate fluctuation based on the calculation of Coulomb stress due to ocean and solid earth tides on the plate interface. We also include the effects of non-tidal ocean variations, such as the Pacific Decadal Oscillation and the Kuroshio Current, employing an ocean model developed by the Japan Meteorological Agency. We apply the method to the Tokai district, where the effects of the Kuroshio Current are large, and demonstrate the importance of considering non-tidal effects. Our calculated slip rate fluctuations could amount to 1 mm/year in decadal scales, and periods with faster rates partly corresponded to variations in seismicity. Slow slip events in the study region weakly corresponded to times of higher stress.

  19. Computer simulations of laser hot spots and implosion symmetry kiniform phase plate experiments on Nova

    SciTech Connect

    Peterson, R. R.; Lindman, E. L.; Delamater, N. D.; Magelssen, G. R.

    2000-05-01

    LASNEX computer code simulations have been performed for radiation symmetry experiments on the Nova laser with vacuum and gas-filled hohlraum targets [R. L. Kauffman et al., Phys. Plasmas 5, 1927 (1998)]. In previous experiments with unsmoothed laser beams, the symmetry was substantially shifted by deflection of the laser beams. In these experiments, laser beams have been smoothed with Kiniform Phase Plates in an attempt to remove deflection of the beams. The experiments have shown that this smoothing significantly improves the agreement with LASNEX calculations of implosion symmetry. The images of laser produced hot spots on the inside of the hohlraum case have been found to differ from LASNEX calculations, suggesting that some beam deflection or self-focusing may still be present or that emission from interpenetrating plasmas is an important component of the images. The measured neutron yields are in good agreement with simulations for vacuum hohlraums but are far different for gas-filled hohlraums. (c) 2000 American Institute of Physics.

  20. Searching for Planets in Holey Debris Disks with the Apodizing Phase Plate

    NASA Astrophysics Data System (ADS)

    Meshkat, Tiffany; Bailey, Vanessa P.; Su, Kate Y. L.; Kenworthy, Matthew A.; Mamajek, Eric E.; Hinz, Philip M.; Smith, Paul S.

    2015-02-01

    We present our first results from a high-contrast imaging search for planetary mass companions around stars with gapped debris disks, as inferred from the stars' bright infrared excesses. For the six considered stars, we model the disks' unresolved infrared spectral energy distributions in order to derive the temperature and location of the disk components. With VLT/NaCo Apodizing Phase Plate coronagraphic L'-band imaging, we search for planetary mass companions that may be sculpting the disks. We detect neither disks nor companions in this sample, confirmed by comparing plausible point sources with archival data. In order to calculate our mass sensitivity limit, we revisit the stellar age estimates. One target, HD 17848, at 540 ± 100 Myr old is significantly older than previously estimated. We then discuss our high-contrast imaging results with respect to the disk properties. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile, ESO under program numbers 090.C-0148(A) and 091.C-0457(A)

  1. Simple method for the analysis of food dyes on reversed-phase thin-layer plates.

    PubMed

    Oka, H; Ikai, Y; Kawamura, N; Yamada, M; Inoue, H; Ohno, T; Inagaki, K; Kuno, A; Yamamoto, N

    1987-12-18

    A technique for the determination of food dyes using reversed-phase thin-layer chromatography on octadecyl-modified silica is described. A solvent system containing 5.0% aqueous sodium sulphate solution enables good separation of the food dyes. Their separation is dependent on the pH of the solvent system, good separation among all dyes being obtained between pH 6.0 and 7.0. The determination of thirteen dyes can be achieved by a combination of methanol-acetonitrile-5.0% aqueous sodium sulphate solution (3:3:10) (solvent system A) and methanol-methyl ethyl ketone-5.0% aqueous sodium sulphate solution (1:1:1) (solvent system B). Solvent system A was used for the determination of Tartrazine, Amaranth, Indigo Carmine, New Coccine, Sunset Yellow FCF, Allura Red AC, Fast Green FCF and Brilliant Blue FCF and for the screening of Acid Red (R-106), Eosin (R-103), Erythrosin (R-3), Rose Bengale (R-105) and Phloxine (R-104). When the spots of R-3, R-103, R-104, R-105 and R-106 appear on the plate, their determination can be achieved by using solvent system B. Each calibration graph was linear between 0.2 and 1.0 micrograms. PMID:3443633

  2. Characteristics of Plate-Fin Heat Exchanger with Phase Change Material

    NASA Astrophysics Data System (ADS)

    Okada, Masashi

    In the present paper, a plate-fin heat exchanger with a phase change material (PCM) was studied. The heat exchanger was a singlepass cross-flow type, where both fluids (air) were unmixed. N-octadecane, of which the fusion temperature is 28.0°C, was used as the PCM. Three kinds of experiments were carried out and the inlet and outlet temperatures and the temperatures in the PCM were measured. In the first experiments, the effectiveness and the overall heat-transfer coefficient were obtained at steady states. By the calculations of steady three-dimensional heat conduction, the effects of the parameters, ---, dimensions, thermal properties, and heat transfer coefficients of air ---, on the overall heat-transfer coefficients were obtaiend clearly. In the second experiments, after the higher-temperature air-flow was stopped, the outlet temperatures of the lower-temperature air were maintained at the constant temperatures for 90-150 minutes. In the third experiments, the higher temperature air was flowed intermittently with an equal interval. The fluctuation of the outlet temperature of the lower-temperature air was within ±2.5°C. The above transient and periodical experiments showed that the present heat exchanger with PCM had useful characters of latent heat storage.

  3. Physical property and Textural transition across the Unconformity and Major Seismic Reflectors in the Upper plate of the Costa Rica Subduction zone offshore Osa Peninsula

    NASA Astrophysics Data System (ADS)

    Hamahashi, M.; Screaton, E.; Tanikawa, W.; Hashimoto, Y.; Martin, K. M.; Saito, S.; Kimura, G.

    2014-12-01

    At the Costa Rica subduction zone offshore Osa Peninsula, the Cocos plate and Cocos Ridge subduct under the Caribbean plate along the Middle America Trench, creating active seismicity. In this region, the Caribbean plate is characterized by a well-consolidated, high velocity framework material beneath the slope sediments, but the nature of the upper plate material is yet unknown. During Integrated Ocean Drilling Program (IODP) Expedition 334 and 344, the unconformity between the slope sediments (Unit 1) and upper plate material (Units 2 and 3) consisting of lithic sedimentary units was penetrated at mid-slope Site 1380. In the current study, to characterize the compaction behavior of the upper plate material, we investigate the physical properties, texture and composition of the sediments at Site 1380 by conducting microstructural observations, resistivity measurements, particle size analyses, X-ray fluorescence and X-ray diffraction analyses. The microstructures of sediments observed through the microscope tend to develop dense and cohesive textures in low porosity sediments, and particle size changes across several unconformities. In particular, the small particle-sized lithic fragments compose larger bodies and form cohesive structures. The cross correlation between measured particle size and shipboard porosity show negative correlation especially at Unit 2, indicating that larger sized particles form smaller or fewer pores. From the results of XRF and XRD analyses, we found that Al, K, Ti tend to concentrate in the higher porosity sediments of Unit 1, whereas Si, Ca, P, Mg, Na, and Mn concentrate in the lower porosity sediments of Unit 2 and 3. The higher concentration in Mg, Na, Mn, Si may be due to minerals such as chlorite, serpentine, amphibole, and sodium manganese. The crossplots between porosity and element concentration show negative correlations in Mg, Na, and Mn with porosity, suggesting that the minerals rich in these elements may relate with the

  4. Modeled temperatures and fluid source distributions for the Mexican subduction zone: Effects of hydrothermal circulation and implications for plate boundary seismic processes

    NASA Astrophysics Data System (ADS)

    Perry, Matthew; Spinelli, Glenn A.; Wada, Ikuko; He, Jiangheng

    2016-02-01

    In subduction zones, spatial variations in pore fluid pressure are hypothesized to control the sliding behavior of the plate boundary fault. The pressure-temperature paths for subducting material control the distributions of dehydration reactions, a primary control on the pore fluid pressure distribution. Thus, constraining subduction zone temperatures are required to understand the seismic processes along the plate interface. We present thermal models for three margin-perpendicular transects in the Mexican subduction zone. We examine the potential thermal effects of vigorous fluid circulation in a high-permeability aquifer within the basaltic basement of the oceanic crust and compare the results with models that invoke extremely high pore fluid pressures to reduce frictional heating along the megathrust. We combine thermal model results with petrological models to determine the spatial distribution of fluid release from the subducting slab and compare dewatering locations with the locations of seismicity, nonvolcanic tremor, slow-slip events, and low-frequency earthquakes. Simulations including hydrothermal circulation are most consistent with surface heat flux measurements. Hydrothermal circulation has a maximum cooling effect of 180°C. Hydrothermally cooled crust carries water deeper into the subduction zone; fluid release distributions in these models are most consistent with existing geophysical data. Our models predict focused fluid release, which could generate overpressures, coincident with an observed ultraslow layer (USL) and a region of nonvolcanic tremor. Landward of USLs, a downdip decrease in fluid source magnitude could result in the dissipation in overpressure in the oceanic crust without requiring a downdip increase in fault zone permeability, as posited in previous studies.

  5. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling.

    PubMed

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne; Szeghalmi, Adriana; Knez, Mato; Weigand, Markus; Snigirev, Anatoly; Snigireva, Irina; Schütz, Gisela

    2013-05-01

    Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ~10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al2O3/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV. PMID:23592622

  6. Testing Single Phase IGBT H-Bridge Switch Plates for the High Voltage Converter Modulator at the Spallation Neutron Source

    SciTech Connect

    Peplov, Vladimir V; Anderson, David E; Solley, Dennis J

    2014-01-01

    Three IGBT H-bridge switching networks are used in each High Voltage Converter Modulator (HVCM) system at the Spallation Neutron Source (SNS) to generate drive currents to three boost transformer primaries switching between positive and negative bus voltages at 20 kHz. Every switch plate assembly is tested before installing it into an operational HVCM. A Single Phase Test Stand has been built for this purpose, and it is used for adjustment, measurement and testing of different configurations of switch plates. This paper will present a description of the Test Stand configuration and discuss the results of testing switch plates with two different types of IGBT gate drivers currently in use on the HVCM systems. Comparison of timing characteristics of the original and new drivers and the resulting performance reinforces the necessity to replace the original H-bridge network drivers with the upgraded units.

  7. Science Road Map for Phase 2 of the Tank-Farm Vadose Zone Program

    SciTech Connect

    Zachara, John M.; Freshley, Mark D.; Mann, Frederick M.

    2008-08-18

    Phase 1 of the Tank-Farm Vadose Zone Program (TFVZP) developed information on the nature and extent of vadose zone contamination in the tank farms through field studies, laboratory analyses and experiments, and historical data searches; assembled data and performed tank-farm risk analysis; and initiated interim corrective actions to lessen the impacts of tank leak contaminants. Pacific Northwest National Laboratory scientists and external collaborators at universities and U.S. Department of Energy user facilities sampled and analyzed contaminant plumes. These types of activities will continue during Phase 2 of the TFVZP to refine and expand scientific understanding of the subsurface beneath tank farms, especially of water movement, residual waste leaching, and contaminant transport.

  8. A rotating condenser and off-axis zone plate monochromator for the TXM at the undulator U41 at BESSY II

    NASA Astrophysics Data System (ADS)

    Niemann, B.; Guttmann, P.; Hambach, D.; Schneider, G.; Weiß, D.; Schmahl, G.

    2001-07-01

    The Göttingen transmission X-ray microscope at the low emittance electron storage ring BESSY II uses the concept of dynamical aperture synthesis (Reynolds, DeVelis, Parrent, Thomson (Eds.), The New Physical Optics Notebook, SPIE, 1990, pp. 536-548) for the object illumination. The concept is well suited as a condenser, as it can match any required numerical aperture of the TXM objective. Furthermore, a novel off-axis transmission zone-plate monochromator is included, which can generate a monochromaticity of several thousand in the object illumination.

  9. Millimeter wave imaging at up to 40 frames per second using an optoelectronic photo-injected Fresnel zone plate lens antenna

    NASA Astrophysics Data System (ADS)

    Robertson, Duncan A.; Gallacher, Thomas F.; Søndenâ, Rune; Macfarlane, David G.

    2016-05-01

    Optoelectronic methods are promising for rapid and highly reconfigurable beam steering across the microwave to the terahertz range. In particular, the photo-injected Fresnel zone plate antenna (piFZPA) offers high speed, wide angle, precise beam steering with good beam quality, to enable video rate millimeter wave imagery with no moving parts. We present a piFZPA demonstrator based on a commercial digital light projector (DLP) and high power laser which achieves steering rates up to 17,500 beams per second at 94 and 188 GHz. We also demonstrate radar imaging at 94 GHz at frame rates of 40 Hz (2D PPI) and 7 Hz (3D volumetric).

  10. Using Time Zones and Celestial Navigation to Teach the Phases of the Moon

    NASA Astrophysics Data System (ADS)

    O'Donoghue, A.

    2011-09-01

    The phases of the moon are typically presented to introductory astronomy classes in a diagram showing the position of the moon, its appearance and elongation at each phase, and the time of each phase's transit. Though wonderfully compact and efficient at conveying information, I have found it to be overwhelming to non-science major students. Much of their difficulty arises from their vague definition of time, which must be broadened for them to understand the different rising, transit, and setting times for the phases of the moon. Working with time zones helps them recognize that the time on their watch is relative to a particular longitude and the transit of the sun at that longitude. Celestial Navigation extends this to the transit of all celestial objects and helps them re-define "time of day" to a position on Earth relative to the Earth-Sun line in a practical way. Once they understand why a given object transits at the same time for all time zones, extending this to the moon is much simpler. My students are quickly able to identify the transit times of the various phases of the moon, and with some additional instruction, quickly learn how to figure out their rising and setting times as well. On this poster, I will include images from PowerPoint animations and the student exercises I use to help them understand the concepts. Though I have too small a sample for statistical analysis (24 students/semester), I have found that student scores on moon phase questions on exams have improved since I incorporated time zones and celestial navigation into my course.

  11. Spiral phase plates for the generation of high-order Laguerre-Gaussian beams with non-zero radial index

    NASA Astrophysics Data System (ADS)

    Ruffato, G.; Carli, M.; Massari, M.; Romanato, F.

    2015-03-01

    The work of design, fabrication and characterization of spiral phase plates for the generation of Laguerre-Gaussian (LG) beams with non-null radial index is presented. Samples were fabricated by electron beam lithography on polymethylmethacrylate layers over glass substrates. The optical response of these phase optical elements was measured and the purity of the experimental beams was investigated in terms of Laguerre-Gaussian modes contributions. The farfield intensity pattern was compared with theoretical models and numerical simulations, while the expected phase features were confirmed by interferometric analyses. The high quality of the output beams confirms the applicability of these phase plates for the generation of high-order Laguerre-Gaussian beams. A novel application consisting in the design of computer-generated holograms encoding information for light beams carrying phase singularities is shown. A numerical code based on iterative Fourier transform algorithm has been developed for the computation of the phase pattern of phase-only diffractive optical element for illumination under LG beams. Numerical analysis and preliminary experimental results confirm the applicability of these devices as high-security optical elements.

  12. A simple and cost-effective solid-phase protein nano-assay using polyacrylamide-coated glass plates.

    PubMed

    Krajewski, Wladyslaw A

    2015-02-01

    A new solid-phase protein nano-assay is suggested for simple and sensitive estimation of protein content in sample buffers (a 1-μl sample is sufficient for analysis). The assay is different from conventional "on-filter" assays in that it uses inexpensive fully transparent polyacrylamide gel (PAAG)-coated glass plates as solid support and, thus, combines the convenience of "on-membrane" staining with the sensitivity and ease of documentation of "in-gel" staining (and, therefore, is especially suited for standard lab gel documentation systems). The PAAG plates assay is compatible with all dyes for in-gel protein staining. Depending on the sensitivity of the staining protocol, the assay can be used in macro-, micro-, and nano-assay formats. We also describe a low-cost two-component colloidal Coomassie brilliant blue G-250 (CBB G-250) staining protocol for fast quantitative visualization of proteins spotted on a PAAG plate (the detection limit is up to 2 ng of proteins even when using a Nikon CoolPix digital camera and white light transilluminator instead of a gel scanner). The suggested colloidal CBB G-250 protocol could also be used for visualizing nano-amounts of proteins in polyacrylamide gels. The PAAG plate assay could be useful for proteomic applications and, in general, for all cases where a fast, sensitive, and easily documentable cost-effective solid-phase protein assay is required. PMID:25449300

  13. Monitoring of slip at the transition zone on the plate interface estimated from non-volcanic deep low-frequency tremors in southwestern Japan

    NASA Astrophysics Data System (ADS)

    Ishida, R.; Hiramatsu, Y.; Obara, K.; Matsuzawa, T.

    2011-12-01

    In southwestern Japan, non-volcanic deep low-frequency (DLF) tremors (e.g., Obara, 2002) and short-term slow slip events (S-SSEs; e.g., Obara et al., 2004) occur in temporal and spatial coincidence with the active stages of DLF tremors (Obara et al., 2004). Based on this feature, Hiramatsu et al. (2008) proposed a method to monitor slip at the transition zone between the locked and aseismic slip zones on the plate interface using DLF tremors. In this study, we applied the method as the same way of previous studies (Hiramatsu et al., 2008; Hirose et al., 2010) and estimated the long-term average slip rate at the transition zone from DLF tremors in southwestern Japan. We also estimated the slip distributions of S-SSEs from DLF tremors using the modified envelope correlation method (ECM) tremor catalog (Maeda and Obara, 2009) and the hourly centroid tremor catalog (Obara et al., 2010) along with the ECM tremor catalog (Obara, 2002) in southwestern Japan. The modified ECM applied both the differential travel time and the spatial distribution of mean square amplitudes to estimate a tremor's spatial location and radiation energy. The hourly centroid tremor catalog is constructed using a clustering process to estimate centroid locations, revealing clear depth-dependent behavior of the tremor activity. The cumulative seismic moment from 2001 to 2009 increases at a constant rate, indicating a constant moment release rate in the long-term average. We estimated slip rate at the transition zone using the formula ˙ {M0} = μ S_˙ {U}, where ˙ {M0} is the moment release rate, μ the rigidity, S the fault area that is related to the slip of S-SSEs in each region, and ˙ {U} the slip rate. We obtained the slip rates of 4.1 ± 0.5 cm/yr, 3.7 ± 0.6 cm/yr, and 2.6 ± 0.2 cm/yr in the western Shikoku, northern Kii peninsula, and Tokai regions, respectively, at the transition zone through the analyzed period. The slip deficit rate at the transition zone in each region is 2.6cm/yr, 2

  14. High-efficiency Fresnel zone plates for hard X-rays by 100 keV e-beam lithography and electroplating

    PubMed Central

    Gorelick, Sergey; Vila-Comamala, Joan; Guzenko, Vitaliy A.; Barrett, Ray; Salomé, Murielle; David, Christian

    2011-01-01

    The fabrication and characterization of Fresnel zone plates (FZPs) for hard X-ray microscopy applications are reported. High-quality 500 nm- and 1 µm-thick Au FZPs with outermost zone widths down to 50 nm and 70 nm, respectively, and with diameters up to 600 µm were fabricated. The diffraction efficiencies of the fabricated FZPs were measured for a wide range of X-ray energies (2.8–13.2 keV) showing excellent values up to 65–75% of the theoretical values, reflecting the good quality of the FZPs. Spatially resolved diffraction efficiency measurements indicate the uniformity of the FZPs and a defect-free structure. PMID:21525653

  15. High-efficiency Fresnel zone plates for hard X-rays by 100 keV e-beam lithography and electroplating.

    PubMed

    Gorelick, Sergey; Vila-Comamala, Joan; Guzenko, Vitaliy A; Barrett, Ray; Salomé, Murielle; David, Christian

    2011-05-01

    The fabrication and characterization of Fresnel zone plates (FZPs) for hard X-ray microscopy applications are reported. High-quality 500 nm- and 1 µm-thick Au FZPs with outermost zone widths down to 50 nm and 70 nm, respectively, and with diameters up to 600 µm were fabricated. The diffraction efficiencies of the fabricated FZPs were measured for a wide range of X-ray energies (2.8-13.2 keV) showing excellent values up to 65-75% of the theoretical values, reflecting the good quality of the FZPs. Spatially resolved diffraction efficiency measurements indicate the uniformity of the FZPs and a defect-free structure. PMID:21525653

  16. Slab stagnation and buckling in the mantle transition zone: Rheology, phase transition, trench migration, and seismic structure

    NASA Astrophysics Data System (ADS)

    Bina, Craig; Cizkova, Hana

    2014-05-01

    Subducting slabs may exhibit buckling instabilities and consequent folding behavior in the mantle transition zone for various combinations of dynamical parameters, accompanied by temporal variations in dip angle, plate velocity, and trench retreat. Parameters governing such behavior include both viscous forces (slab and mantle rheology) and buoyancy forces (slab thermal structure and mineral phase relations). 2D numerical experiments show that many parameter sets lead to slab deflection at the base of the transition zone, typically accompanied by quasi-periodic oscillations (consistent with previous scaling analyses) in largely anticorrelated plate and rollback velocities, resulting in undulating stagnant slabs as buckle folds accumulate subhorizontally atop the lower mantle. Slab interactions with mantle phase transitions are important components of this process (Bina and Kawakatsu, 2010; Čížková and Bina, 2013). For terrestrial parameter sets, trench retreat is found to be nearly ubiquitous, and trench advance is quite rare - due to both rheological structure and ridge-push effects (Čížková and Bina, 2013). Recent analyses of global plate motions indicate that significant trench advance is also rare on Earth, being largely restricted to the Izu-Bonin arc (Matthews et al., 2013). Consequently, we explore the conditions necessary for terrestrial trench advance through dynamical models involving the unusual geometry associated with the Philippine Sea region. Detailed images of buckled stagnant slabs are difficult to resolve due to smoothing effects inherent in seismic tomography, but velocity structures computed for compositionally layered slabs, using laboratory data on relevant mineral assemblages, can be spatially low-pass filtered for comparison with tomographic images of corresponding resolution. When applied to P-wave velocity anomalies from stagnant slab material beneath northeast China, model slabs which undulate due to compound buckling fit

  17. Refined Views of Strike-slip Fault Zones, Seismicity, and State of Stress Associated With the Pacific-North America Plate Boundary in Southern California

    NASA Astrophysics Data System (ADS)

    Hauksson, E.; Nicholson, C.; Shaw, J. H.; Plesch, A.; Shearer, P. M.; Sandwell, D. T.; Yang, W.

    2013-12-01

    The mostly strike-slip plate boundary in southern California is expressed as a system of late Quaternary faults or principal slip zones (PSZs), with numerous adjacent smaller slip surfaces. It is complex, even after large cumulative displacements, and consists of major fault systems with multi-stranded, non-planar fault geometry, including some in close proximity to each other. There are also secondary cross faults and low-angle detachments that interact with the PSZs accommodating main plate boundary motion. The loading of plate-tectonic strain causes the largest earthquakes along PSZs, moderate-sized events in their immediate vicinity, and small earthquakes across the whole region. We apply relocated earthquake and refined focal mechanism (1981-2013) catalogs, as well as other geophysical datasets to provide refined views of the 3D fault geometry of these active fault systems. To determine properties of individual fault zones, we measure the Euclidian distance from every hypocenter to the nearest PSZ. In addition, we assign crustal geophysical parameters such as heat flow value and shear or dilatation strain rates to each epicenter. We investigate seismogenic thickness and fault zone width as well as earthquake source processes. We find that the seismicity rate is a function of location, with the rate dying off exponentially with distance from the PSZ. About 80% of small earthquakes are located within 5 km of a PSZ. For small earthquakes, stress drops increase in size with distance away from the PSZs. The magnitude distribution near the PSZs suggests that large earthquakes are more common close to PSZs, and they are more likely to occur at greater depth than small earthquakes. In contrast, small quakes can occur at any geographical location. An optimal combination of heat flow and strain rate is required to concentrate the strain along rheologically weak fault zones, which accommodate the crustal deformation processes, causing seismicity. The regional trend of

  18. Rapid Kinematic and Tectonic Variations Along the 1400-km-long Australia-Woodlark Plate Boundary Zone, Papua New Guinea and Woodlark Basin

    NASA Astrophysics Data System (ADS)

    Mann, P.; Taylor, F. W.; Gahagan, L.; Watson, L.

    2004-12-01

    Previous GPS studies have shown the wide variability in present-day plate motions across the highly arcuate, 1400-km-long Australia-Woodlark plate boundary extending from Papua New Guinea to the Solomon Islands. GPS-determined motions range from orthogonal oceanic spreading in the Woodlark basin, to continental transtension in the 2.5-km-high core complex area of easternmost Papua New Guinea, to continental strike-slip and transpression in 4-km-high mountains of the Papuan Peninsula. We use imagery, earthquake focal mechanisms, coral reef uplift data, and structural mapping studies to establish the along-strike continuity of the active plate boundary fault. Systematic angular changes in the direction of the plate vector along this continuous fault explain its varied tectonic geomorphology, Holocene uplift history, and geologic structure. We use a series of plate reconstructions to illustrate the longer term, Cenozoic evolution of this boundary including: its formation as an arcuate, N- and NE-dipping ophiolitic suture zone during Paleogene time, the progressive "unzippering" of this thrust over the past 6 Ma along a N- and NE-dipping, low-angle normal fault in easternmost Papua New Guinea, and its "zippering" or continued shortening on the suture thrust in the Owen Stanley Ranges of the Papuan Peninsula. Over the 1400-km-length of the fault, the length of segments of oceanic spreading, transtension, and transpression is 250-500 km; the time period separating one tectonic style from the succeeding style encroaching from the east is several million years. This systematic spatial and temporal superposition of tectonic styles, leads to complex - but predictable - along-strike variations in geologic history.

  19. Fluid-structure interaction study of the splitter plate in a TBCC exhaust system during mode transition phase

    NASA Astrophysics Data System (ADS)

    Guo, Shuai; Xu, Jinglei; Mo, Jianwei; Gu, Rui; Pang, Lina

    2015-07-01

    Splitter plate plays an important role in a turbine-based combined-cycle (TBCC) exhaust system during the mode transition phase when turbojet engine and ramjet engine operate simultaneously. Dissimilar pressure distribution on both sides of the plate has a potential origin in the aeroelastic coupling, which is an interesting topic while few research works have devoted to that aspect. To better understand the aeroelastic behavior of the plate and the corresponding dynamic flow features, an integrated fluid-structure interaction simulation is conducted under one particular operation condition during mode transition phase in the TBCC exhaust system. A finite-volume-based CFD solver FLUENT is adopted to solve the unsteady Reynolds average Navier-Stokes equations. ABAQUS, a finite-element-method-based CSD solver, is employed to compute the plate elastic deformation. A two-way interaction between the fluid and the structure is accomplished by the mesh-based parallel-code coupling interface (MpCCI) in a loosely-coupled manner. The accuracy of the coupling procedure is validated for the flutter of a flat plate in supersonic flow. Then, features of steady flow field of the TBCC exhaust system are discussed, followed by the investigation of the aeroelastic phenomenon of the splitter plate and the evolution process of the flow field pattern. Finally, performances variation of the exhaust system is obtained and discussed. The results show that the plate vibrates with decaying amplitude and reaches a dynamic stable state eventually. The thrust, lift and pitch moment of the TBCC exhaust system are increased by 0.68%, 2.82% and 5.86%, respectively, compared with the corresponding values in steady state which does not take into account the fluid-structure interaction effects. The analysis reveals the importance of considering the fluid-structure interaction effects in designing the splitter plate in the TBCC exhaust system and demonstrates the availability of the present coupled

  20. Selective higher order fiber mode excitation using a monolithic setup of a phase plate at a fiber facet

    NASA Astrophysics Data System (ADS)

    Wilde, Johannes; Schulze, Christian; Brüning, Robert; Duparré, Michael; Schröter, Siegmund

    2015-03-01

    Controlling the modal content coupled into an optical fiber can be desirable in many situations, e.g. for adjusting the sensitivity of the guided field distribution to external perturbations1. For this purpose we used a monolithic setup of a phase plate at a fiber input facet to excite selectively higher order modes, which theoretically can provide a mode purity of more than 99%. We investigated the capabilities of this approach by complete modal decomposition of the fiber output signals, considering the achievable mode purity with respect to several possible imperfections of the setup. The experiments are compared with detailed numerical simulations and show a high agreement. Additionally a comparison with a well known setup with free space phase plates2-4 was undertaken. This showed the monolithic setup to be energetically twice as efficient.

  1. Distribution of plates' sizes tell the thermal history in a simulated martensitic-like phase transition

    NASA Astrophysics Data System (ADS)

    Ţolea, F.; Ţolea, M.; Sofronie, M.; Văleanu, M.

    2015-07-01

    A phenomenological 2D model, simulating the martensitic transformation, is built upon existing experimental observations that the size of the formed plates - in direct transformation - decreases as the temperature is lowered; then they transform back in reversed order. As such, if a reverse transformation is incomplete (arrested), the subsequent direct one will show anomalously a large number of big size plates - old plus newly formed - but consequentially a depletion of intermediate sizes, due to geometrical constraints, phenomenon that generates thermal memory.

  2. Direct observation of the topological charge of a terahertz vortex beam generated by a Tsurupica spiral phase plate

    SciTech Connect

    Miyamoto, K.; Suizu, K.; Akiba, T.; Omatsu, T.

    2014-06-30

    A terahertz (THz) spiral phase plate with high transmission (>90% after Fresnel correction) and low dispersion has been developed based on the Tsurupica olefin polymer. Direct observations of the topological charge (both magnitude and sign) of a THz vortex beam are performed by using a THz camera with tilted lens focusing and radial defect introduction. The vortex outputs with a topological charge of ±1 (or ±2) are obtained at a frequency of 2 (or 4) THz.

  3. GPS measurements of crustal deformation within the Pacific-Australia plate boundary zone in Irian Jaya, Indonesia

    NASA Astrophysics Data System (ADS)

    Puntodewo, S. S. O.; McCaffrey, R.; Calais, E.; Bock, Y.; Rais, J.; Subarya, C.; Poewariardi, R.; Stevens, C.; Genrich, J.; Fauzi; Zwick, P.; Wdowinski, S.

    1994-10-01

    Global Positioning System (GPS) measurements made in 1991, 1992 and 1993 provide preliminary estimates of slip distribution between the Australian and Pacific plates in Irian Jaya, Indonesia. We interpret the GPS results with constraints from earthquake mechanisms and slip vectors, recent marine surveys, and geology. Three GPS sites in southeastern Irian Jaya show motions that are within 10 mm/yr of the expected motion of Australia. A coast-to-coast N-S baseline along 140.5°E crosses all known onland regions of active deformation but reveals no more than 15 mm/yr of shortening and 20 mm/yr of left-lateral shear in the 27-month period. The remaining 40 mm/yr of expected convergence between the Pacific and Australian plates probably occurs at the New Guinea trough. GPS sites on the island of Biak, at 136°E, and at Sorong, near the western tip of Bird's Head (at 131°E), both move 90-100 mm/yr in a WSW direction relative to Irian Jaya, but less than 15 mm/yr relative to each other. These sites are on either side of the Sorong fault and demonstrate that it is not presently the major boundary between the Australian and Pacific plates. Instead the plate boundary is now south of the Sorong and Biak sites. Earthquakes suggest possible structures that accomodate motion between Bird's Head and Australia but the relative importance of them remains uncertain.

  4. Effect of fringe-artifact correction on sub-tomogram averaging from Zernike phase-plate cryo-TEM.

    PubMed

    Kishchenko, Gregory P; Danev, Radostin; Fisher, Rebecca; He, Jie; Hsieh, Chyongere; Marko, Michael; Sui, Haixin

    2015-09-01

    Zernike phase-plate (ZPP) imaging greatly increases contrast in cryo-electron microscopy, however fringe artifacts appear in the images. A computational de-fringing method has been proposed, but it has not been widely employed, perhaps because the importance of de-fringing has not been clearly demonstrated. For testing purposes, we employed Zernike phase-plate imaging in a cryo-electron tomographic study of radial-spoke complexes attached to microtubule doublets. We found that the contrast enhancement by ZPP imaging made nonlinear denoising insensitive to the filtering parameters, such that simple low-frequency band-pass filtering made the same improvement in map quality. We employed sub-tomogram averaging, which compensates for the effect of the "missing wedge" and considerably improves map quality. We found that fringes (caused by the abrupt cut-on of the central hole in the phase plate) can lead to incorrect representation of a structure that is well-known from the literature. The expected structure was restored by amplitude scaling, as proposed in the literature. Our results show that de-fringing is an important part of image-processing for cryo-electron tomography of macromolecular complexes with ZPP imaging. PMID:26210582

  5. Plate tectonics conserves angular momentum

    NASA Astrophysics Data System (ADS)

    Bowin, C.

    2010-03-01

    A new combined understanding of plate tectonics, Earth internal structure, and the role of impulse in deformation of the Earth's crust is presented. Plate accelerations and decelerations have been revealed by iterative filtering of the quaternion history for the Euler poles that define absolute plate motion history for the past 68 million years, and provide an unprecedented precision for plate angular rotation variations with time at 2-million year intervals. Stage poles represent the angular rotation of a plate's motion between adjacent Euler poles, and from which the maximum velocity vector for a plate can be determined. The consistent maximum velocity variations, in turn, yield consistent estimates of plate accelerations and decelerations. The fact that the Pacific plate was shown to accelerate and decelerate, implied that conservation of plate tectonic angular momentum must be globally conserved, and that is confirmed by the results shown here (total angular momentum ~1.4+27 kg m2 s-1). Accordingly, if a plate decelerates, other plates must increase their angular momentums to compensate. In addition, the azimuth of the maximum velocity vectors yields clues as to why the "bend" in the Emperor-Hawaiian seamount trend occurred near 46 Myr. This report summarizes processing results for 12 of the 14 major tectonic plates of the Earth (except for the Juan de Fuca and Philippine plates). Plate accelerations support the contention that plate tectonics is a product of torques that most likely are sustained by the sinking of positive density anomalies revealed by geoid anomalies of the degree 4-10 packet of the Earth's spherical harmonic coefficients. These linear positive geoid anomalies underlie plate subduction zones and are presumed due to phase changes in subducted gabbroic lithosphere at depth in the upper lower mantle (above 1200 km depth). The tectonic plates are pulled along by the sinking of these positive mass anomalies, rather than moving at near constant

  6. [The plate in the zone of oocyte and germinal epithelium contact in scyphomedusa Aurelia aurita binds antibodies to ZP-domain-containing protein mesoglein].

    PubMed

    Adonin, L S; Podgornaia, O I; Matveev, I V; Shaposhnikova, T G

    2009-01-01

    Cnidaria are lower multicellular animals with the body consisting of two epithelial layers. An extracellular substance--mesoglea--is situated between epidermal and gastrodermal layers of these animals. Mesoglein is one of the major mesogleal proteins of adult medusa of Scyphozoan jellyfish Aurelia aurita. Search for the known domains in mesoglein amino acid sequence reveals prominent zona pellucida (ZP) domain (which was found at first in the mammal oocyte zona pellucida proteins), so the protein belongs to ZP family of extracellular matrix proteins and it is an early metazoan member of ZP-domain-containing protein family. However, nothing is known about oogenesis related ZP-domain proteins in the lower multicellular animals. Oogenesis in Scyphozoa is described poorly. In this work morphological features of the zone in contact area between the oocyte and the germinal epithelium were investigated in semi-fine sections: To make it more convenient we identified seven stages according to the oocyte size and the structure found in this area was named the plate. It was shown that the components of the plate bound specifically the antibodies against mesoglein. So it seems the plate material contains ZP-domain proteins. Electrophoresis and immunoblot results give evidence that the proteins immunologically related to mesoglein have a higher molecular mass. It might be due to either the posttranslational modifications of the precursors or that they represent other proteins of ZP-domain family in Cnidaria. PMID:19566035

  7. Evidence for shallow dehydration of the subducting plate beneath the Mariana forearc: New insights into the water cycle at subduction zones

    NASA Astrophysics Data System (ADS)

    Ribeiro, J.; Stern, R. J.; Kelley, K. A.; Shaw, A. M.; Martinez, F.; Ohara, Y.

    2014-12-01

    Water is efficiently recycled at subduction zones. It is fluxed from the surface into the mantle by the subducted plate and back to the surface or crust through explosive arc volcanism and degassing. Fluids released from dehydrating the subducting plate are transfer agents of water. Geophysical modeling [1] and the geochemistry of arc glasses [2] suggest that at cold-slab subduction zones, such as the Mariana convergent margin, the downgoing plate mostly dehydrates beneath the volcanic arc front (≥ ~ 80 -100 km depth to slab) to trigger volcanism. However, there is a gap in our understanding of the water fluxes released beneath forearcs, as examples of forearc magmatism are extremely rare. Here, we investigate the Southernmost Mariana Forearc Rift (SEMFR), where MORB-like spreading occurred unusually close to the trench, sampling slab-derived aqueous fluids released at ~ 30 to 100 km depth from the subducted plate. Examining the trace element and water contents of olivine-hosted melt inclusions and glassy rinds from the young (2 - 4 Ma) and fresh SEMFR pillowed basalts provide new insights into the global water cycle. SEMFR lavas contain ~2 wt % H2O, and the olivine-hosted melt inclusions have the highest subduction-related H2O/Ce ratios (H2O/Ce = 6000 - 19000) ever recorded in arc magmas (H2O/Ce < 10600 and global averaged H2O/Ce < 3000). Our findings show that (i) slab-derived fluids released beneath forearcs are water-rich compared to the deeper fluids released beneath the arc system; and (ii) cold downgoing plates lose most of their water at shallow depths (~ 70 - 80 km slab depth), suggesting that water is efficiently recycled beneath the forearc (≥ 90%). 1. Van Keken, P.E., et al., Subduction factory: 4. Depth-dependent flux of H2O from subducting slabs worldwide. Journal of Geophysical Research: Solid Earth, 2011. 116(B1): p. B01401, DOI: 10.1029/2010jb007922. 2. Ruscitto, D.M., et al., Global variations in H2O/Ce: 2. Relationships to arc magma

  8. Plate-mantle interaction through time explains two-phase uplift history of the eastern Australian passive margin

    NASA Astrophysics Data System (ADS)

    Dietmar Müller, R.; Flament, Nicolas; Matthews, Kara J.; Williams, Simon E.; Gurnis, Michael

    2015-04-01

    The origin of passive margin mountains is a hotly debated topic in geodynamics. The Eastern Highlands of Australia are a type example whose uplift history has been investigated for several decades, with suggested mechanisms ranging from flexural rift shoulder uplift, volcanism and underplating to mantle-convection driven dynamic topography. Most of the highlands have experienced a distinct two-phase uplift history, with the first phase being Late Cretaceous in age, followed by a mid-late Cenozoic renewal in uplift, but the timing and magnitude of uplift differs along strike. We investigate the origin of the Eastern Highlands with a coupled plate-mantle model, using a thorough parameter space analysis, including two alternative subduction boundary evolution models. The first model includes a large (~1000 km width at its maximum extent) Early Cretaceous (140-120 Ma) back-arc basin east of the Lord Howe Rise, representing the now subducted South Loyalty Basin which may have formed due to eastward rollback of the long-lived west-dipping eastern Gondwanaland subduction zone; the alternative scenario is based on the premise that west-dipping subduction is continuous to the East of the Lord Howe Rise between 140-85 Ma, without a large back-arc basin, and the South Loyalty Basin opening as a back arc basin from 85-55 Ma, which is subsequently consumed by subduction. We further investigate the influence of a low-viscosity asthenosphere and of the viscosity profile of the lower mantle on dynamic topography, as well as the effect of changing the buoyancy of the basal dense layer (LLSVP) that contributes to the long-wavelength Pacific superswell. Our best-fit model produces a total uplift up to ~400 m in the interval between 120 and 90-70 Ma, well-matched with recent published estimates from river profile inversion for the Snowy Mountains, New England and the Central Highlands. The driving mechanism is rebound from the eastwards motion of Australia over a sinking slab, first

  9. Structure and composition of the plate-boundary slip zone for the 2011 Tohoku-Oki earthquake.

    PubMed

    Chester, Frederick M; Rowe, Christie; Ujiie, Kohtaro; Kirkpatrick, James; Regalla, Christine; Remitti, Francesca; Moore, J Casey; Toy, Virginia; Wolfson-Schwehr, Monica; Bose, Santanu; Kameda, Jun; Mori, James J; Brodsky, Emily E; Eguchi, Nobuhisa; Toczko, Sean

    2013-12-01

    The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes. PMID:24311682

  10. A revised estimate of Pacific-North America motion and implications for Western North America plate boundary zone tectonics

    NASA Technical Reports Server (NTRS)

    Demets, Charles; Gordon, Richard G.; Stein, Seth; Argus, Donald F.

    1987-01-01

    Marine magnetic profiles from the Gulf of Californa are studied in order to revise the estimate of Pacific-North America motion. It is found that since 3 Ma spreading has averaged 48 mm/yr, consistent with a new global plate motion model derived without any data. The present data suggest that strike-slip motion on faults west of the San Andreas is less than previously thought, reducing the San Andreas discrepancy with geodetic, seismological, and other geologic observations.

  11. Large aperture kinoform phase plates in fused silica for spatial beam smoothing on Nova and the Beamlet Lasers

    SciTech Connect

    Rushford, M.C.; Dixit, S.N.; Thomas, I.M.; Martin, A.M.; Perry, M.D.

    1997-03-01

    It is now widely recognized that spatial beam smoothing (homogenization) is essential in coupling the laser energy to the inertial confinement fusion (ICF) targets. For the indirect drive approach to ICF, it is desirable to distribute the laser energy into a uniformly speckled profile that has a flat-top super-Gaussian envelope (8th power or higher) and contains greater than 95% of the energy inside the super-Gaussian profile. Spatial smoothing is easily achieved by introducing a binary random phase plate (RPP) in the beam. This produces a homogenized far-field pattern which consists of an overall envelope function determined by the RPP element superimposed with a fine scale speckle pattern arising due to the interference among the various RPP elements. Although easy to fabricate and currently in routine use in many fusion laboratories, the binary RPPs do not meet the ICF requirements stated above since the far-field intensity profile is restricted to essentially an Airy function containing only 84% (an upper limit) of the energy inside the central spot. Approaches using lenslet arrays (refractive or diffractive) have limited use since they operate in the quasi-far-field and have a short depth of focus. The limitations of the RPPs can be overcome by relaxing the binary phase constraint. We have recently presented 5 continuously varying phase screens for tailoring the focal plane irradiance profiles. Called kinoform phase plates (KPPs), these phase screens offer complete flexibility in tailoring the focal plane envelope and, at the same time, increasing the energy efficiency inside the focal spot. In this paper we discuss the design and fabrication of such kinoform phase plates in fused silica for spatial beam smoothing on the Nova and the Beamlet lasers. Since the phase plates are used at the end of the laser chain, KPPs on Nova and Beamlet have to be fabricated on large aperture optics (65-cm diameter and 40-cm square substrates respectively). The following

  12. Distribution and mechanism of Neogene to present-day vertical axis rotations, Pacific-Australian Plate Boundary Zone, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Little, Timothy A.; Roberts, Andrew P.

    1997-01-01

    Remarkably little knowledge exists about mechanisms of vertical axis rotation in continental crust. Steeply dipping basement rocks in South Island, New Zealand, provide an opportunity to map the distribution of rotations across the Pacific-Australian plate boundary zone, and to delineate boundaries of rotated blocks in unusual detail. We synthesize new structural data with new and existing paleomagnetic data, with geodetic data, and with patterns of Neogene-Quaternary faulting in the strike-slip Marlborough fault system. For the past 20 m.y., vertical axis rotations have been hinged about two crustal-scale boundaries near the east coast. The NE hinge accommodated ˜50° of early-middle Miocene clockwise rotation, which caused deformation of the eastern ends of the Alpine-Wairau and Clarence strike-slip faults. The SW hinge has accommodated a further 30°-50° of finite clockwise rotation since ˜4 Ma and deflects active fault traces. The locus of rotation has shifted southwestward astride a subduction margin that is lengthening in that direction. Rotating rocks are pinned to the south against a locked collision zone where the continental Chatham Rise impinges against the margin. Slip on inland strike-slip faults is transformed seaward across a zone of fault termination into rigid body rotation of a large continental block that has been thrust eastward over the downgoing subducted slab of the Pacific plate. The rotation mechanism is a "migrating hinge," which resembles a flexed telephone book. Strike-slip faults are translated through a brecciated hinge region that does not coincide with a fixed material line in the rock.

  13. Overriding plate structure of the Nicaragua convergent margin: Constraints on the limits of the seismogenic zone and the 1992 tsunami earthquake

    NASA Astrophysics Data System (ADS)

    Sallarès, V.; Meléndez, A.; Prada, M.; Ranero, C. R.; McIntosh, K.; Grevemeyer, I.

    2012-04-01

    We present 2D P-wave velocity models of the Nicaragua convergent margin along two perpendicular wide-angle seismic profiles acquired in the rupture area of the 1992 tsunami earthquake. The models focus on the structure of the overriding plate and the geometry of the inter-plate boundary. In the trench-perpendicular profile, the basement shows increasing velocity reflecting a progressive decrease in the degree of rock fracturing of the igneous basement. Upper mantle-like velocities are obtained at a depth of ~10 km beneath the fore-arc Sandino basin, indicating that the mantle wedge is shallow and located close to the trench. A mismatch between the inter-plate reflector in the velocity models and along coincident multi-channel seismic profiles is best explained by a ~15% velocity anisotropy, suggesting locally-enhanced rock fracturing which is related with the presence of a prominent subducted seamount. The frontal part of the overriding plate is probably too fractured to store elastic energy, unless the presence of local asperities such as the subducted seamount makes it conditionally stable by locally increasing the normal stress. The downdip limit of the seismogenic zone occurs near the tip of the mantle wedge, indicating that it is probably controlled by the presence of a weak, serpentinized mantle wedge beneath the Sandino basin. The hypocenter of the 1992 main shock is not particularly shallow (20-22 km), but seismological data indicate that it triggered sub-events near the trench, the main of which coincides with the subducted seamount. We show that the slow propagation velocity and long duration of the 1992 earthquake could be explained by rupture propagating within the fractured basement rocks and not into the sediments.

  14. A comparative study of zone axis pattern maps from decagonal phases with varying periodicity

    SciTech Connect

    Ranganathan, S. . Dept of Materials Science and Metallurgy Indian Inst. of Science, Bangalore . Dept. of Metallurgy); Singh, A. . Dept. of Metallurgy); Mukhopadhyay, N.K.; Weatherly, G.C. . Dept. of Metallurgy)

    1994-02-01

    The discovery in 1985 of the decagonal phase with periodicity in one direction and quasiperiodicity in the other two directions has excited considerable interest. This was followed by the observation that the periodicity perpendicular to the quasiperiodicity plane can assume multiple values on n = [1,2,3,4]x0.4 nm. The mapping of reciprocal spaces of these phases, labelled t[sub 2n], by electron diffraction is important in the context of atomic models for the decagonal phase. While partial determinations have been available for T[sub 4] context of atomic models for the decagonal phase. While partial determinations have been available for T[sub 4] [Al-Co], T[sub 6][Al-Mn] and T[sub 8] [Al-Fe], [Al-Pd], the recent complete determination of zone axis pattern maps [ZAPM] and Kikuchi maps of T[sub 6] [Al-Mn] with 1.24 nm periodicity and T[sub 4][Al-Cu-Co-Si] with 0.8 nm periodicity is a tour de force by Kelton and his co-workers. These papers coupled with the complete mapping of the HOLZ line and Kikuchi line patterns of the T[sub 2][Al-Co-Ni] with 0.4 nm periodicity permit the authors to put in perspective the ZAPM of all the four decagonal phases and in addition predict patterns for the T[sub 8] phase for which a complete experimental determination is still lacking.

  15. Initial phase zone for phase locking to the resonance, using “main condition” of phase stability in DC-biased single-sided multipactor

    SciTech Connect

    Mostajeran, M.

    2014-05-15

    In the present work, the concept of accurate phase stability is employed to study a DC-biased single-sided multipactor. A “main condition” of phase stability was introduced in our previous studies of two-sided multipactors [M. Mostajeran, J. Instrum. 8, P04024 (2013); M. Mostajeran and M. Lamehi Rachti, Nucl. Instrum. Methods Phys. Res. A 615, 1–5 (2010)]. Using the same condition and assuming zero initial velocity for the secondary electrons, a regime of multipactors outside the resonance zones is found. The theoretical results are then verified by numerical simulation.

  16. Laves phase in alloy 718 fusion zone — microscopic and calorimetric studies

    SciTech Connect

    Manikandan, S.G.K.; Sivakumar, D.; Prasad Rao, K.; Kamaraj, M.

    2015-02-15

    Microstructural characterization of alloy 718 fusion zone welded with both solid solution and age hardenable filler metal has been done. The microsegregation and the aging response were studied by employing three levels of weld cooling rate. Gas Tungsten Arc welding process was used. The fusion zone of solid solution filler metal has been responding to the aging treatment due to the weld process conditions and weld metal chemistry. However the weld metal composition was modified due to the higher molybdenum (Mo) content in solid solution filler metal. The effect of this modification on the phase reaction temperatures was studied and the same was compared with the conventional filler metal. - Graphical abstract: Display Omitted - Highlights: • Interdendritic segregation has been controlled by weld cooling rate. • Laves phase formation has been studied with cooling rate and weld metal chemistry. • Aging response with solid solution filler metal has been demonstrated. • Reduction in Laves phase and alloying element segregation has been confirmed. • Reaction temperatures were found modified because of Mo addition.

  17. Transient Deformation at the Seismic-Aseismic Transition in a Mature Plate Boundary Fault Zone - New Zealand's Alpine Fault

    NASA Astrophysics Data System (ADS)

    Toy, V. G.; Norris, R. J.; Prior, D. J.

    2008-12-01

    During the seismic cycle, stresses and strain rates fluctuate in the viscously-deforming zones down-dip of large faults. These transient events produce geological records that can be preserved in exhumed fault zones that have experienced single ruptures (e.g. Sesia Zone, European Western Alps). On the other hand, in major faults that have not experienced a simple, single rupture history, coseismic structures are likely to be destroyed during subsequent cycles of postseismic creep. New Zealand's active Alpine Fault has likely experienced upwards of 20,000 Mw~8 earthquakes, on average one every 200-300 years, over the last ≥5 million years of dextral-reverse slip. Fault rocks generated during these events are exhumed in the hangingwall, exposing materials deformed throughout the seismogenic zone at the surface. We have recognised a structural record of transient events in these rocks that differs from that previously reported elsewhere. Mylonites were formed by viscous shearing of a metasedimentary protolith downdip of the seismogenic structure. Rheological models predict these mylonites should have passed through a crustal strength peak (τ ≥100 MPa) around the brittle-viscous transition. Immediately prior to passing through this transition, they should have developed a small recrystallised grainsize (~10-15μm) and a crystallographic preferred orientation (CPO) indicating slip on the basal system during quartz dislocation creep, as well as a retrograde greenschist-facies mineralogy. However, the high-strain mylonites preserve a large recrystallised grainsize (>~30μm), amphibolite-facies mineralogy and CPO characteristic of prism slip. This suggests they were not significantly deformed at temperatures below ~450°C, significantly above the lower temperature limit for quartz crystal-plasticity at steady-state strain rates in the fault zone Microstructural observations and textural data indicate variable deformation style through the seismic cycle. Large fault

  18. Dextral strike-slip along the Kapıdağ shear zone (NW Turkey): evidence for Eocene westward translation of the Anatolian plate

    NASA Astrophysics Data System (ADS)

    Türkoğlu, Ercan; Zulauf, Gernold; Linckens, Jolien; Ustaömer, Timur

    2016-07-01

    The northern part of the Kapıdağ Peninsula (Marmara Sea, NW Turkey) is affected by the E-W trending Kapıdağ shear zone, which cuts through calc-alkaline granitoids of the Ocaklar pluton resulting in mylonitic orthogneiss. Macroscopic and microscopic shear-sense indicators, such as SC fabrics, shear bands, σ-clasts and mica fish, unequivocally suggest dextral strike-slip for the Kapıdağ shear zone. Based on petrographic data, deformation microfabrics of quartz and feldspar, and the slip systems in quartz, the dextral shearing should have been active at T = 500-300 °C and P < 5 kbar. Published K-Ar and 39Ar-40Ar cooling ages of hornblende and biotite suggest that cooling below 500-300 °C occurred during the Eocene (ca. 45-ca. 35 Ma), meaning that the Kapıdağ shear zone should have been active during Middle to Late Eocene times. The differential stress related to the shearing was <50 MPa as is indicated by the size of recrystallized quartz grains. Based on the new and published data, it is concluded that the westward movement of the Anatolian plate might have been active almost continuously from the Middle Eocene until recent times.

  19. Paper microzone plates.

    PubMed

    Carrilho, Emanuel; Phillips, Scott T; Vella, Sarah J; Martinez, Andres W; Whitesides, George M

    2009-08-01

    This paper describes 96- and 384-microzone plates fabricated in paper as alternatives to conventional multiwell plates fabricated in molded polymers. Paper-based plates are functionally related to plastic well plates, but they offer new capabilities. For example, paper-microzone plates are thin (approximately 180 microm), require small volumes of sample (5 microL per zone), and can be manufactured from inexpensive materials ($0.05 per plate). The paper-based plates are fabricated by patterning sheets of paper, using photolithography, into hydrophilic zones surrounded by hydrophobic polymeric barriers. This photolithography used an inexpensive formulation photoresist that allows rapid (approximately 15 min) prototyping of paper-based plates. These plates are compatible with conventional microplate readers for quantitative absorbance and fluorescence measurements. The limit of detection per zone loaded for fluorescence was 125 fmol for fluorescein isothiocyanate-labeled bovine serum albumin, and this level corresponds to 0.02 the quantity of analyte per well used to achieve comparable signal-to-noise in a 96-well plastic plate (using a solution of 25 nM labeled protein). The limits of detection for absorbance on paper was approximately 50 pmol per zone for both Coomassie Brilliant Blue and Amaranth dyes; these values were 0.4 that required for the plastic plate. Demonstration of quantitative colorimetric correlations using a scanner or camera to image the zones and to measure the intensity of color, makes it possible to conduct assays without a microplate reader. PMID:19572563

  20. Characterization of livestock odors using steel plates, solid-phase microextraction, and multidimensional gas chromatography-mass spectrometry-olfactometry.

    PubMed

    Bulliner, Edward A; Koziel, Jacek A; Cai, Lingshuang; Wright, Donald

    2006-10-01

    Livestock operations are associated with emissions of odor, gases, and particulate matter (PM). Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa and, in the process, identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for < or =1 week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid-phase microextraction was used to extract characteristic odorants collected on the plates. All of the analyses were conducted on a gas chromatography-mass spectrometry-olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via mass spectrometry. Multidimensional chromatography was used to isolate and identify chemicals with high-characteristic swine odor. The effects of sampling time, distance from a source, and the presence of PM on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor, as well as attributing to p-cresol the largest odor response out of the samples. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions. PMID:17063862

  1. Effect of the Reunion plume head on Indo-Atlantic plate motions: evidence from the bend along the Southwest Indian ridge fracture zones

    NASA Astrophysics Data System (ADS)

    Cande, S. C.; Stegman, D. R.; Patriat, P.

    2011-12-01

    It was recently shown that the arrival at the Earth's surface of the Reunion plume head had a major effect on the motions of the Indo-Atlantic plates between 68 and 45 Ma (Cande and Stegman, 2011). The primary evidence for this is the observation that the motions of the Indian and African plates appear to have been coupled during this period: when the Indian plate speeds up between 68 and 66 Ma (from 80 to 180 mm/yr relative to Africa), the convergence of Africa with Eurasia slows down and perhaps stops, and when the Indian plate slows down between 52 and 45 Ma, Africa-Eurasia convergence speeds up. The fast motion of India relative to Africa is well documented by seafloor spreading anomalies and can be divided into three stages: 1) between 66 and 63 Ma, corresponding to the formation of the Deccan traps, when India moves superfast (roughly 180 mm/yr), 2) between 63 and 52 Ma when the speed of India is roughly 100 mm/yr, which is fast but not superfast, and 3) between 52 and 45 Ma when India's motion gradually slows from 100 to 40 mm/yr. The changes in Africa's motion are best recorded in the systematic "swings" of the Euler stage poles constraining the motion of Africa relative to North America, South America and Antarctica. The stage poles (relative to Africa) on all three plate pairs move along arcs first away from and then back towards the Africa-Eurasia Euler pole, constraining a major slowdown of the African plate relative to Eurasia which reaches its nadir between 57 and 53 Ma before returning to its pre-slowdown motion around 45 Ma. The systematic slowing and speedup of Africa is recorded in the great bends of the fracture zones in the Central Atlantic, South Atlantic and Southwest Indian ridges. Since the Indian and African plates were on opposite sides of the Reunion plume relative to Eurasia, the synchroneity of the plate motion changes strongly suggests that the plume head was a major driving force and, in particular, that the slow down of India between

  2. Planar gas chromatography column on glass plate with nanodispersed silica as the stationary phase

    NASA Astrophysics Data System (ADS)

    Platonov, I. A.; Platonov, V. I.; Pavelyev, V. S.; Agafonov, A. N.

    2016-04-01

    The paper presents the GC column in the plane of the glass plate with the adsorption layer nanodispersed silica. Created gas chromatographic column allows to separate a mixture of five alkanes from pentane to nonane in isothermal (90 ° C) mode less than one minute.

  3. Variation of b and p values from aftershocks sequences along the Mexican subduction zone and their relation to plate characteristics

    NASA Astrophysics Data System (ADS)

    Ávila-Barrientos, L.; Zúñiga, F. R.; Rodríguez-Pérez, Q.; Guzmán-Speziale, M.

    2015-11-01

    Aftershock sequences along the Mexican subduction margin (between coordinates 110ºW and 91ºW) were analyzed by means of the p value from the Omori-Utsu relation and the b value from the Gutenberg-Richter relation. We focused on recent medium to large (Mw > 5.6) events considered susceptible of generating aftershock sequences suitable for analysis. The main goal was to try to find a possible correlation between aftershock parameters and plate characteristics, such as displacement rate, age and segmentation. The subduction regime of Mexico is one of the most active regions of the world with a high frequency of occurrence of medium to large events and plate characteristics change along the subduction margin. Previous studies have observed differences in seismic source characteristics at the subduction regime, which may indicate a difference in rheology and possible segmentation. The results of the analysis of the aftershock sequences indicate a slight tendency for p values to decrease from west to east with increasing of plate age although a statistical significance is undermined by the small number of aftershocks in the sequences, a particular feature distinctive of the region as compared to other world subduction regimes. The b values show an opposite, increasing trend towards the east even though the statistical significance is not enough to warrant the validation of such a trend. A linear regression between both parameters provides additional support for the inverse relation. Moreover, we calculated the seismic coupling coefficient, showing a direct relation with the p and b values. While we cannot undoubtedly confirm the hypothesis that aftershock generation depends on certain tectonic characteristics (age, thickness, temperature), our results do not reject it thus encouraging further study into this question.

  4. Pore Fluid Pressure and State of Stress Above the Plate Interface from Observations in a 3 Kilometer Deep Borehole: IODP Site C0002, Nankai Trough Subduction Zone

    NASA Astrophysics Data System (ADS)

    Tobin, H. J.; Saffer, D. M.; Hirose, T.; Castillo, D. A.; Kitajima, H.; Sone, H.

    2014-12-01

    During IODP Expedition 348 from October 2013 to January 2014, Site C0002 was drilled to more than 3000 meters' depth into the inner accretionary wedge at the Nankai Trough, setting a new depth record for scientific ocean drilling. It is the first hole to access the deep interior of an active convergent margin. Site C0002 is part of the NanTroSEIZE project off the Kii-Kumano region of Japan, designed to shed light on plate boundary fault zone processes near the up-dip edge of seismogenic locking and slip. The zone from 865 - 3056 meters below the sea floor was sampled via logging-while-drilling measurements, continuous sampling of drill cuttings, and limited coring. This interval was composed of lithified middle to late Miocene hemipelagic sediments and turbidites that are markedly deformed and dip steeply. P-wave speeds from sonic logs increase with depth to ~ 1600 meters, but are constant to slightly decreasing with depth from 1600 to 3050 meters. We hypothesize that this change in trend indicates the onset of elevated pore fluid pressure, but structural and lithologic factors may also play a role. We explore several methods for quantitative estimation of sonic-derived fluid pressure conditions in the inner wedge. A borehole leak-off test (LOT) and a series of borehole pressurization and injection tests were also performed, which we synthesize to estimate the least principal stress, or Shmin. Furthermore, downhole pressure while drilling (PWD) measurements recorded during borehole packoff events provide information on the maximum principal stress, SHmax. Taken together, the LOT and PWD observations suggest that the inner wedge at ~ 2000 meters depth is currently in a strike-slip stress regime, despite its position as the hanging wall of a main plate boundary thrust. This may be a transitional stress regime between shallow normal and deep thrust, controlled by depth-dependent magnitude of the tectonic convergence-related principal stress. Our results document for

  5. Comparative analysis of equatorial and auroral-zone phase scintillation data. Technical report, 13 March 1985-30 September 1986

    SciTech Connect

    Rino, C.L.; Dabbs, T.M.

    1986-10-01

    A comparison is made between equatorial and auroral-zone phase scintillation. The spectral characteristics of weak-scatter phase-scintillation data collected at two equatorial ground stations are contrasted with similar data collected at two auroral-zone ground stations. An automated, multisegmented fitting procedure was used to determine these characteristics. Three types of spectra were found. Despite temporal and spatial differences, the two equatorial data sets have similar spectral characteristics. The auroral-zone sets are also similar. In contrast, the spectral characteristics of the two latitude regions are quite different from each other.

  6. Jurassic Cordilleran dike swarm-shear zones: Implications for the Nevadan orogeny and North American plate motion

    SciTech Connect

    Wolf, M.B.; Saleeby, J.B. )

    1992-08-01

    A cogenetic and coeval tonalitic and mafic dike swarm has been identified within a southern fragment (the Owens Mountain area) of the western Foothills terrane (California). The dikes were mylonitized and transposed (rotated into subparallel orientation) during emplacement, from 155 to 148 Ma (U-Pb zircon data), which coincides in time with the Nevadan orogeny. Steeply southeast-plunging fold axes and S-fold geometries indicate a sinistral-sense of shear, possibly with some dip-slip motion as well. This shear zone may be the southern and possibly deeper extension of the Bear Mountains fault zone. This and other Late Jurassic Cordilleran dike swarms record a complex pattern of sinistral-sense transtension-transpression that developed at the apparent-polar-wander J2 cusp ([approximately] 150 Ma) and during subsequent, rapid, northwestward acceleration of North America. The Late Jurassic Nevadan orogeny is a manifestation of these dramatic changes in magnitude and direction of North American motion.

  7. Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate.

    PubMed

    Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

    2014-03-15

    Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO4(-)) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase (14)C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with (14)C-TCE. Transport experiments showed that MnO4(-) alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO4(-), the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP+MnO4(-) improved TCE destruction by ∼16% over MnO4(-) alone (56.5% vs. 40.1%). These results support combining permanganate with SHMP or SHMP and xanthan as a means of treating high concentrations of TCE in low permeable zones. PMID:24491441

  8. Phase transformations in the transition zone of the mantle and possible changes in the earth's radius

    NASA Astrophysics Data System (ADS)

    Barsukov, V. L.; Urusov, V. S.

    1982-12-01

    A survey of the sequence of phase transitions in the MgO-FeO-SiO2 system under the conditions of the earth's mantle shows that experimentally observed structural state transformations correctly explain the principal discontinuities encountered in the increase in density with depth within the earth. The properties of the ilmenite, corundum, and perovskite modifications of MgSiO3 are evaluated for what is believed to be the first time. It is shown that all the transformations occurring in the upper mantle and in the transition zone proceed with a positive slope of dP/dT, whereas the transition into a mixture of the perovskite modification and periclase (MgO), which explains the boundary between the transition zone and the lower mantle, has a negative slope. An assessment is made of the changes that may have occurred in the density of individual layers deep within the earth in response to the increasing depth of phase transformations. It is believed that this effect may have been responsible for increases in the earth's radius by 3-5% over the last two billion years.

  9. Feedback Structure-Borne Sound Control of a Flexible Plate with AN Electromagnetic Actuator: the Phase Lag Problem

    NASA Astrophysics Data System (ADS)

    Ren, M. Z.; Seto, K.; Doi, F.

    1997-08-01

    In this paper an experimental study is presented on active control of a clamped plate at audio frequencies by using feedback controller and electromagnetic actuator. The controller is designed with modern control theory on a lumped parameter model of the plate, and is then implemented in experiments to control the real structure. In practice, the optimal control force cannot be generated exactly as desired due to the non-ideal characteristics of the control system. Several factors such as A/D and D/A convertors, velocity estimation through approximate differentiation, and the electromagnetic actuator are examined in respect to their frequency features. An analytical model is developed to predict the phase lag of the actual control force to the designed control force. It is shown that if the phase lag is over 90 degrees, the control system will become unstable. Two techniques are discussed for improving the system performance that is mainly affected by the electromagnetic actuator when the high speed sampling and processing device is used as the controller. The simple and practical method is to employ a phase-lead compensation network in the control circuit. Another one that is more fundamental is to incorporate the characteristics of the actuator into the system by feeding back the current passing through the actuator into the controller. Various experiments are carried out to verify the analysis and the proposed methods, and the potentials of the electromagnetic actuator in controlling the high frequency vibration and noise are therefore demonstrated.

  10. GPS and Geologic Deformation Rates Agree to Within Uncertainties in the Arabia-Africa- Eurasia Zone of Plate Interaction

    NASA Astrophysics Data System (ADS)

    Reilinger, R. E.; McClusky, S.

    2008-12-01

    Geodetically-derived motions for Arabia and Nubia relative to Eurasia agree within 1 standard deviation with plate rates estimated from geologic observations (McQuarrie et al., GRL, 2003) for the past 11 Myr for Nubia and greater than 25 Myr for Arabia. Furthermore, fault slip rates derived from an elastic block model constrained by GPS agree within uncertainties (about +/- 15 percent) with geologically determined, long-term slip rates in this complex area of plate interaction. Detailed geomorphological studies of the central North Anatolian fault (NAF) constrained by quantitative dating (Kozaci et a al., Geology, 2007) indicate slip rates that agree within uncertainties, but appear to be systematically lower than geodetic rates. While real rate changes of a few mm/yr cannot be ruled out at present, we note that geodetic inversions for coseismic fault slip on the NAF, and most other faults well constrained by geodetic observations, indicate larger slip at depth than at the surface. If this difference persists throughout the earthquake deformation cycle, it would account for the small difference in geodetic and geologic rates. Extrapolating present-day geodetic motions for Arabia relative to Nubia and Somalia to the time of initiation of Red Sea and Gulf of Aden extension indicates that Arabia separated from Nubia and Somalia simultaneously along the full extent of both rifts at about 25 Myr BP, consistent with independent geologic estimates for the style, and age of initiation of Red Sea extension (Omar and Steckler, 1995, Science). In addition, structural offsets across the Gulf of Suez (GoS) and Gulf of Aqaba (GoA) are consistent with a transfer of strain form the GoS to the GoA at around 12 Ma BP, roughly consistent with the age on initiation of the Dead Sea fault system. We further show that the apparent discrepancy between geodetic deformation of the Aegean (plate-like motion with low internal deformation), and geologic deformation (extensive crustal thinning

  11. Design of an electron microscope phase plate using a focused continuous-wave laser

    SciTech Connect

    Spence, J.; Muller, H; Jin, Jian; Danev, R; Padmore, H; Glaeser, R.M

    2010-07-01

    We propose a Zernike phase contrast electron microscope that uses an intense laser focus to convert a phase image into a visible image. We present the relativistic quantum theory of the phase shift caused by the laser–electron interaction, study resonant cavities for enhancing the laser intensity and discuss applications in biology, soft-materials science and atomic and molecular physics.

  12. Design of an electron microscope phase plate using a focused continuous-wave laser

    PubMed Central

    Müller, H; Jin, Jian; Danev, R; Spence, J; Padmore, H; Glaeser, R M

    2010-01-01

    We propose a Zernike phase contrast electron microscope that uses an intense laser focus to convert a phase image into a visible image. We present the relativistic quantum theory of the phase shift caused by the laser–electron interaction, study resonant cavities for enhancing the laser intensity and discuss applications in biology, soft-materials science and atomic and molecular physics. PMID:20808709

  13. Fluid budgets at convergent plate margins: Implications for the extent and duration of fault-zone dilation

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    1999-01-01

    Faults at convergent plate boundaries are important conduits for fluid escape, and recent evidence suggests that fluid expulsion along them is both transient and heterogeneous. For the Nankai and Barbados convergent margins, we have used numerical models to investigate the long-term partitioning of expelled fluids between diffuse flow and flow along connected high-permeability fault conduits. For a simple case of spatial heterogeneity, we estimated the extent of high-permeability conduits necessary to maintain a balance between incoming and expelled fluids. For the case of transient expulsion, we constrained the duration of elevated permeability required to balance the fluid budgets. Comparison of modeled and observed geochemical profiles suggests that the initiation of connected flow conduits is delayed with respect to the time of accretion into each accretionary complex and may be related to burial below a critical depth, either where the overlying wedge is sufficiently thick to prevent fluid escape to the sea floor or where sediments behave brittlely.

  14. Two-phase modeling of mushy zone parameters associated with hot tearing

    SciTech Connect

    Farup, I.; Mo, A.

    2000-05-01

    A two-phase continuum model for an isotropic mushy zone is presented. The model is based upon the general volume-averaged conservation equations, and quantities associated with hot tearing are included, i.e., after-feeding of the liquid melt due to solidification shrinkage is taken into account as well as thermally induced deformation of the solid phase. The model is implemented numerically for a one-dimensional model problem with some similarities to the aluminum direct chill (DC) casting process. The variation of some key parameters that are known to influence the hot-tearing tendency is then studied. The results indicate that both liquid pressure drop due to feeding difficulties and tensile stress caused by thermal contraction of the solid phase are necessary for the formation of hot tears. Based upon results from the one-dimensional model, it is furthermore concluded that none of the hot-tearing criteria suggested in the literature are able to predict the variation in hot-tearing susceptibility resulting from a variation in all of the following parameters: solidification interval, cooling contraction of the solid phase, casting speed, and liquid fraction at coherency.

  15. Modeling metabolic reductive dechlorination in dense non-aqueous phase liquid source-zones

    NASA Astrophysics Data System (ADS)

    Christ, John A.; Abriola, Linda M.

    2007-06-01

    Recent laboratory experimental evidence has suggested that bioremediation may be an attractive management strategy for dense non-aqueous phase liquid (DNAPL) source-zones. In particular, metabolic reductive dechlorination has been shown to reduce aqueous phase chlorinated ethene contaminant concentrations and enhance DNAPL dissolution, reducing source longevity. Transitioning this technology from the laboratory to the field will be facilitated by tools capable of simulating bioenhanced dissolution. This work presents a mathematical model for metabolic reductive dechlorination in a macroscale two-phase (aqueous-organic) environment. The model is implemented through adaptation of an existing multi-phase compositional simulator, which has been modified to incorporate eight chemical components and four microbial populations: a fermentative population, two dechlorinating populations, and a competitor population (e.g., methanogens). Monod kinetics, modified to incorporate electron donor thresholds, electron acceptor competition, and competitor inhibition, are used to simulate microbial growth and component degradation. The developed model is numerically verified and demonstrated through comparisons with published column-scale dechlorination data. Dechlorination kinetics, electron donor concentrations, and DNAPL saturation and distribution are all found to affect the extent of dissolution enhancement, with enhancements ranging from 1.0 to ˜1.9. Comparison of simulation results with those from a simplified analytic modeling approach suggest that the analytical model may tend to over-predict dissolution enhancement and fail to account for the transient nature of dissolution enhancement, leading to significant (70%) under-prediction of source longevity.

  16. Continuous contour phase plates for tailoring the focal plane irradiance profile

    SciTech Connect

    Dixit, S.N.; Rushford, M.C.; Thomas, I.M.; Perry, M.D.

    1995-08-09

    We present fully continuous phase screens for producing super-Gaussian focal-plane irradiance profiles. Such phase screens are constructed with the assumption of either circular symmetric near-field and far-field profiles or a separable phase screen in Cartesian co-ordinates. In each case, the phase screen is only a few waves deep. Under illumination by coherent light, such phase screens produce high order super-Gaussian profiles in the focal plane with high energy content effects of beam aberrations on the focal profiles and their energy content are also discussed.

  17. Optical anisotropy, zoning, and coexistence of two cubic phases in andradites from Quebec and New York

    NASA Astrophysics Data System (ADS)

    Antao, Sytle M.; Zaman, Mashrur; Gontijo, Vitor L.; Camargo, Eric S.; Marr, Robert A.

    2015-02-01

    The crystal structure of two zoned birefringent andradite garnets, ideally Ca3Fe2 3+Si3O12, from (1) Black Lake, Quebec (QC) and (2) Willsboro, New York (NY), was refined with the Rietveld method, space group , and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Electron probe microanalyzer results gave bulk or average compositions as follows: (1) Ca3[Fe{1.92/3+}Al0.07Mn{0.01/3+}Mg0.01]Σ2Si3O12, Adr96Grs3 and (2) {Ca2.99Mg0.01Mn{0.01/2+}}Σ3[Fe{1.52/3+}Al0.47Ti0.01]Σ2(Si2.98Al0.02)Σ3O12, Adr76Grs23. The HRPXRD data show the coexistence of two cubic phases as intergrowths in both samples. Phase-1a of the QC sample-1 has a composition of near-end-member andradite, and phase-1b is Adr91Grs9. For the NY sample-2, phase-2a is Adr76Grs23 and phase-2b is Adr59Grs39. The reduced χ2 and overall R ( F 2) Rietveld refinement values are 1.074 and 0.0268 for the QC sample, and 1.172 and 0.0333 for the NY sample. For the QC sample, the weight percentage and unit-cell parameter for phase-1a are 67.0(1) % and a = 12.06077(1) Å, and those for phase-1b are 33.0(1) % and a = 12.0535(1) Å with Δ a = 0.007 Å. For the NY sample, the corresponding values for phase-2a are 81.3(1) % and a = 12.00456(1) Å, and those for phase-2b are 18.7(1) % and a = 11.96687(1) Å with Δ a = 0.038 Å. The two cubic phases are intergrown and cause strain that arises from structural mismatch and gives rise to strain-induced birefringence. The above two samples are compared to andradite samples from Arizona and Magnet Cove.

  18. Near Fault Observatories (NFO) services and integration plan for European Plate Observing System (EPOS) Implementation Phase

    NASA Astrophysics Data System (ADS)

    Chiaraluce, Lauro

    2016-04-01

    Coherently with the EPOS vision aimed at creating a pan-European infrastructure for Earth Sciences supporting research for a more sustainable society, we are working on the integration of NFOs and services implementation facilitating their data and products discovery and usage. NFOs are National Research Infrastructures (NRI) consisting of advanced networks of multi-parametric sensors continuously monitoring the chemical and physical processes related to the common underlying Earth instabilities governing active faults evolution and the genesis of earthquakes. These infrastructures will enable advancements in understanding of earthquakes generation processes and associated ground shaking due to their high-quality near-source multidisciplinary data. In EPOS-IP seven NFOs are going to be linked: 1) the Altotiberina and 2) Irpinia Observatories in Italy, 3) Corinth in Greece, 4) South-Iceland Seismic Zone, 5) Valais in Switzerland, 6) Marmara Sea (GEO Supersite) in Turkey and 7) Vrancea in Romania. EPOS-IP aims to implement integrated services from a technical, legal, governance and financial point of view. Accordingly, our first effort within this first core group of NFOs will be establishing legal governance for such a young community to ensure a long-term sustainability of the envisaged services including the full adoption of the EPOS data policy. The establishment of a Board including representatives of each NFO formally appointed by the Institutions supporting the NRI is a basic requirement to provide and validate a stable governance mechanism supporting the initiatives finalised to the services provision. Extremely dense networks and less common instruments deserve an extraordinary work on data quality control and description. We will work on linking all the NFOs in a single distributed network of observatories with instrumental and monitoring standards based on common protocols for observation, analysis, and data access and distributed channels. We will rely on

  19. The Vincent Fault in the San Gabriel Mtns, southern California, USA: a modified plate boundary shear zone

    NASA Astrophysics Data System (ADS)

    Xia, Haoran; Platt, John

    2015-04-01

    The Vincent Fault in southern California separates the ocean-affiliated Pelona schist of Late Cretaceous age in the footwall from a Meso-Proterozoic gneiss complex and Mesozoic granitoid rocks in the hanging wall. The Vincent fault has been regarded as the original megathrust formed during Laramide flat-slab subduction. Our new pressure, temperature and geochronologic data from the rocks in the hanging wall and the footwall indicate that the Vincent fault has undergone post-subduction modification. The Pelona schist in the San Gabriel Mtns was metamorphosed up to high-pressure greenschist facies. The peak metamorphic temperature given by laser Raman spectroscopy of carbonaceous material is 518.9 ± 19.6°C, consistent with the temperature range of 515-550°C from the quartz c-axis opening-angle thermometer. The peak pressure yielded by Si-in-muscovite barometry is 10.5 ± 1 kbar. The upper ~50 m of the Pelona schist was then mylonitized together with the lower 500-800 m of the hanging wall, which overprinted the pre-existing texture. Mylonitization produced a strong ESE-trending lineation in both rock units, with a consistent ESE sense of shear: opposite to what would be predicted by E-directed subduction. Pressure and temperature of mylonitization of the Pelona schist and the lower part of the hangingwall mylonite zone constrained by the Ti-in-quartz thermobarometer and Si-in-muscovite barometer is around ~4.7 kbar and 372 to 425°C; whereas the upper part of the mylonite zone was equilibrated at ~2.4 kbar and ~365°C. The quartz c-axis fabric opening-angle thermometer also gives a temperature range from 360 to 420°C in the entire mylonite zone. Mylonitization therefore took place during exhumation and cooling of the Pelona Schist. Fission track ages of detrital zircons from both the footwall and the hanging wall of the Vincent fault cluster around 46.7 ± 5.9 Ma, indicating that both footwall and hanging wall had cooled to ~200°C by that time. No other major

  20. Distribution of Luliconazole in Nail Plate by In Vitro Permeation and Efficacy by Zone of Inhibition Test after Treatment of Luliconazole Nail Solution.

    PubMed

    Shimamura, Tsuyoshi; Miyamae, Akiko; Arai, Masakazu; Minemura, Aya; Nozawa, Akira; Kubota, Nobuo

    2016-01-01

    To clarify the character of luliconazole nail solution we have developed, we investigated luliconazole distribution and antifungal activity in nail plate. An in vitro permeation study which measured luliconazole concentration of sliced nail in the transverse direction after treatment of luliconazole nail solution was conducted to investigate for concentration dependency and the influences of nail thickness and treatment duration. When 0.2, 1, 3, 5, and 7.5% luliconazole nail solutions were used, luliconazole was detected in the all the layers of nail and there was a concentration gradient from the dorsal side to deep nail layers. The luliconazole concentration was almost same after 14-day treatment with 5% luliconazole nail solution when using nails of different thicknesses. And we confirmed that concentration of luliconazole into the nail was increased depending on the treatment duration. In zone of inhibition test after 14-day treatment, 5% luliconazole nail solution showed statistically high formation rate of zones of inhibition compared to 8% ciclopirox nail lacquer. Above all, these data suggested that 5% luliconazole nail solution has the potential to show high therapeutic effect for onychomycosis. PMID:26936348

  1. Relationship between phase difference and coefficient of restitution during low velocity foreign object transverse damage of composite plates

    NASA Technical Reports Server (NTRS)

    Lal, K. M.

    1984-01-01

    This work discusses a model to correlate the coefficient of restitution of low velocity transverse impacts of graphite-epoxy laminates with the residual deformation or central deflection at the end of the impact event. It is assumed that the energy absorbed by the target can be calibrated in terms of residual deflection, and thereby in terms of phase difference between the occurrence of impact force and central deflection to their maximas. Analysis was modeled on the basis of the experience from impact tests. Predictions are compared with the test results of impacted circular and flat plates. Experimentally measured values of coefficient of restitution and phase difference agreed well with the predicted relationship between them.

  2. Thermochemical Analysis of Phases Formed at the Interface of a Mg alloy-Ni-plated Steel Joint during Laser Brazing

    NASA Astrophysics Data System (ADS)

    Nasiri, Ali M.; Chartrand, Patrice; Weckman, David C.; Zhou, Norman Y.

    2013-04-01

    The thermodynamic stability of precipitated phases at the steel-Ni-Mg alloy interface during laser brazing of Ni-plated steel to AZ31B magnesium sheet using AZ92 magnesium alloy filler wire has been evaluated using FactSage thermochemical software. Assuming local chemical equilibrium at the interface, the chemical activity-temperature-composition relationships of intermetallic compounds that might form in the steel-Ni interlayer-AZ92 magnesium alloy system in the temperature range of 873 K to 1373 K (600 °C to 1100 °C) were estimated using the Equilib module of FactSage. The results provided better understanding of the phases that might form at the interface of the dissimilar metal joints during the laser brazing process. The addition of a Ni interlayer between the steel and the Mg brazing alloy was predicted to result in the formation of the AlNi, Mg2Ni, and Al3Ni2 intermetallic compounds at the interface, depending on the local maximum temperature. This was confirmed experimentally by laser brazing of Ni electro-plated steel to AZ31B-H24 magnesium alloy using AZ92 magnesium alloy filler wire. As predicted, the formation of just AlNi and Mg2Ni from a monotectic and eutectic reaction, respectively, was observed near the interface.

  3. Oxidation of ammonium sulfite by a multi-needle-to-plate gas phase pulsed corona discharge reactor

    NASA Astrophysics Data System (ADS)

    Ren, Hua; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

    2013-03-01

    The oxidation of ammonium sulfite in the ammonia-based flue gas desulfurization (FGD) process was investigated in a multi-needle-to-plate gas phase pulsed corona discharge reactor in this paper. The effect of several parameters, including capacitance and peak pulse voltage of discharge system, electrode gap and bubbling gas flow rate on the oxidation rate of ammonium sulfite was reviewed. The oxidation rate of ammonium sulfite could reach 47.2% at the capacitance, the peak pulse voltage, electrode gap and bubbling gas flow rate equal to 2 nF, -24.6 k V, 35 mm and 4 L min-1 within treatment time of 40 min The experimental results indicate that the gas phase pulsed discharge system with a multi-needle-to-plate electrode can oxide the ammonium sulfite. The oxidation rate increased with the applied capacitance and peak pulse voltage and decreased with the electrode gap. As the bubbling gas flow rate increased, the oxidation rate increased first and then tended to reach a stationary value. These results would be important for the process optimization of the (NH4)2SO3 to (NH4)2SO4 oxidation.

  4. Holocene faulting in the Bellingham forearc basin: upper-plate deformation at the northern end of the Cascadia subduction zone

    USGS Publications Warehouse

    Kelsey, Harvey M.; Sherrod, Brian L.; Blakely, Richard J.; Haugerud, Ralph A.

    2013-01-01

    The northern Cascadia forearc takes up most of the strain transmitted northward via the Oregon Coast block from the northward-migrating Sierra Nevada block. The north-south contractional strain in the forearc manifests in upper-plate faults active during the Holocene, the northern-most components of which are faults within the Bellingham Basin. The Bellingham Basin is the northern of four basins of the actively deforming northern Cascadia forearc. A set of Holocene faults, Drayton Harbor, Birch Bay, and Sandy Point faults, occur within the Bellingham Basin and can be traced from onshore to offshore using a combination of aeromagnetic lineaments, paleoseismic investigations and scarps identified using LiDAR imagery. With the recognition of such Holocene faults, the northernmost margin of the actively deforming Cascadia forearc extends 60 km north of the previously recognized limit of Holocene forearc deformation. Although to date no Holocene faults are recognized at the northern boundary of the Bellingham Basin, which is 15 km north of the international border, there is no compelling tectonic reason to expect that Holocene faults are limited to south of the international border.

  5. Determination of retardation parameters of multiple-order wave plate using a phase-sensitive heterodyne ellipsometer.

    PubMed

    Hsieh, Cheng-Hung; Tsai, Chien-Chung; Wei, Hsiang-Chun; Yu, Li-Ping; Wu, Jheng-Syong; Chou, Chien

    2007-08-10

    To characterize the linear birefringence of a multiple-order wave plate (MWP), an oblique incidence is one of the methods available. Multiple reflections in the MWP are produced, and oscillations in the phase retardation measurement versus the oblique incident angle are then measured. Therefore, an antireflection coated MWP is required to avoid oscillation of the phase retardation measurement. In this study, we set up a phase-sensitive heterodyne ellipsometer to measure the phase retardations of an uncoated MWP versus the oblique incident angle, which was scanned in the x-z plane and y-z plane independently. Thus, the effect on multiple reflections by the MWP is reduced by means of subtracting the two measured phase retardations from each other. As a result, a highly sensitive and accurate measurement of retardation parameters (RPs), which includes the refractive indices of the extraordinary ray n(e) and ordinary ray n(o), is obtained by this method. On measurement, a sensitivity (n(e),n(o)) of 10(-6) was achieved by this experiment setup. At the same time, the spatial shifting of the P and S waves emerging from the MWP introduced a deviation between experimental results and the theoretical calculation. PMID:17694147

  6. Analytical Round Robin for Elastic-Plastic Analysis of Surface Cracked Plates: Phase I Results

    NASA Technical Reports Server (NTRS)

    Wells, D. N.; Allen, P. A.

    2012-01-01

    An analytical round robin for the elastic-plastic analysis of surface cracks in flat plates was conducted with 15 participants. Experimental results from a surface crack tension test in 2219-T8 aluminum plate provided the basis for the inter-laboratory study (ILS). The study proceeded in a blind fashion given that the analysis methodology was not specified to the participants, and key experimental results were withheld. This approach allowed the ILS to serve as a current measure of the state of the art for elastic-plastic fracture mechanics analysis. The analytical results and the associated methodologies were collected for comparison, and sources of variability were studied and isolated. The results of the study revealed that the J-integral analysis methodology using the domain integral method is robust, providing reliable J-integral values without being overly sensitive to modeling details. General modeling choices such as analysis code, model size (mesh density), crack tip meshing, or boundary conditions, were not found to be sources of significant variability. For analyses controlled only by far-field boundary conditions, the greatest source of variability in the J-integral assessment is introduced through the constitutive model. This variability can be substantially reduced by using crack mouth opening displacements to anchor the assessment. Conclusions provide recommendations for analysis standardization.

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

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sumit

    2016-04-01

    these rocks are the ages of peak of metamorphism in the presence of melt, rather than from the prograde path. When these information are combined with those from phase equilibria and geospeedometry, a systematic P-T-t history of the rocks may be constructed and as a result, a history of pulsed motion along the MCT may be obtained. Dates of rocks from the MCT zone itself, on the other hand, preserve one point in the P-T-t evolution. It can be shown that different isotopic systems (e.g. Lu-Hf in garnet vs. U-Th-Pb in monazites or zircons) preserve dates from different stages of this pulsed history and interpolating linearly between them to obtain rates of motion may give misleading results. Combination of both kinds of information with proper attention to the P-T history of the rocks yields the most internally consistent picture of motion along the fault zone. Ref: Anzckiewicz, R., Chakraborty, S., Dasgupta, S., Mukhopadhyay, D., Koltonik, K.: Timing, duration and inversion of prograde Barrovian metamorphism constrained by high resolution Lu-Hf garnet dating: A case study from the Sikkim Himalaya, NE India; Earth and Planetary Science Letters, Volume 407, Pages 70 - 81, DOI: 10.1016/j.eps1.2014.09.035

  8. IMMOBILIZATION OF RADIONUCLIDES IN THE HANFORD VADOSE ZONE BY INCORPORATION IN SOLID PHASES

    SciTech Connect

    Traina, Samuel J.

    2000-06-01

    We propose to investigate (1) the effect of aging on the stability of sorption complexes on Al-oxide and Al-oxyhydroxide surfaces formed from neutralization and homogeneous nucleation of alkaline aluminate solutions; (2) the sorption/coprecipitation of these elements in solids formed from reaction of alkaline aluminate solutions with simple systems of representative minerals and mineral coatings found in the soils and sediments underlying the Hanford Tank Farm (e.g., quartz, feldspars, biotite, muscovite, chlorite,clay mineral, augite, hornblende, ilmenite, magnetite, hematite, Fe(III)- oxyhydroxides, and Mn(IV)-(hydr)oxides); and (3) the sorption/coprecipitation of these elements in solids formed from reaction of alkaline aluminate solutions with soil and sediment samples obtained from the Hanford site. (4) To couple these laboratory studies to precipitation processes occurring in the Hanford vadose zone beneath the Tank Farm, we also propose to characterize the particle coatings and precipitate phases in core samples from this zone. These investigations will utilize X-ray Absorption Fine Structure (XAFS) spectroscopy, vibrational spectroscopy, NMR spectroscopy, electron and X-ray microprobe analyses, transmission electron microscopy, X-ray photoelectron spectroscopy, and other characterization studies of the speciation and spatial distribution of the these ions in several model systems chosen to simulate the natural systems.

  9. IMMOBILIZATION OF RADIONUCLIDES IN THE HANFORD VADOSE ZONE BY INCORPORATION IN SOLID PHASES

    SciTech Connect

    Traina, Samuel J.; Grandinetti, Philip; Brown Jr., Gordon E. Ainsworth, Calvin C.; Szecsody, Jim E.

    2001-06-01

    Specific objectives are to investigate (1) the effect of aging on the stability of sorption complexes on Al-oxide and Al-oxyhydroxide surfaces formed from neutralization and homogeneous nucleation of alkaline aluminate solutions; (2) the sorption/coprecipitation of these elements in solids formed from reaction of alkaline aluminate solutions with simple systems of representative minerals and mineral coatings found in the soils and sediments underlying the Hanford Tank Farm (e.g., quartz, feldspars, biotite, muscovite, chlorite,clay mineral, augite, hornblende, ilmenite, magnetite, hematite, Fe(III)- oxyhydroxides, and Mn(IV)-(hydr)oxides); and (3) the sorption/coprecipitation of these elements in solids formed from reaction of alkaline aluminate solutions with soil and sediment samples obtained from the Hanford site. (4) To couple these laboratory studies to precipitation processes occurring in the Hanford vadose zone beneath the Tank Farm, we also propose to characterize the particle coatings and precipitate phases in core samples from this zone. These investigations will utilize X-ray Absorption Fine Structure (XAFS) spectroscopy, vibrational spectroscopy, NMR spectroscopy, electron and X-ray microprobe analyses, transmission electron microscopy, X-ray photoelectron spectroscopy, and other characterization studies of the speciation and spatial distribution of the these ions in several model systems chosen to simulate the natural systems.

  10. A recent phase of accretion along the southern Costa Rican subduction zone

    NASA Astrophysics Data System (ADS)

    Bangs, Nathan L.; McIntosh, Kirk D.; Silver, Eli A.; Kluesner, Jared W.; Ranero, César R.

    2016-06-01

    In 2011 we acquired a 3D seismic reflection volume across the Costa Rica margin NW of the Osa Peninsula to investigate the complex structure and the development of the seismogenic zone within the Costa Rican subduction zone in the vicinity of recent International Ocean Drilling Program (IODP) drilling. In contrast to previous interpretations, these newly acquired seismic images show that the margin wedge is composed of a layered fabric that is consistent with clastic sediments, similar to materials recovered from IODP drilling, that have been thrust and thickened into thrust-bounded folded sequences. These structures are consistent with a balanced sequence that has been frontally accreted in the context of an accretionary model. We interpret these sequences as sediment originally deposited on the subducting crust in a trench basin created by the southward migration of the Cocos-Nazca-Caribbean triple junction, and accreted during recent margin subduction that also accelerated with passage of the triple junction. The margin is composed of relatively rapidly accreted sediment that was added to the margin during a phase of accretion within the last ∼5 Ma that was probably preceded throughout the Neogene by periods of non-accretion or erosion.

  11. Dehydration kinetics of talc and 10 Å phase: Consequences for subduction zone seismicity

    NASA Astrophysics Data System (ADS)

    Chollet, Mélanie; Daniel, Isabelle; Koga, Kenneth T.; Petitgirard, Sylvain; Morard, Guillaume

    2009-06-01

    The process of dehydration embrittlement is usually proposed as an explanation for the presence of intermediate-depth earthquakes in subduction zones. It assumes that the release of water by hydrous mineral breakdown is fast enough to provoke brittle failure. We performed high-pressure, high-temperature, dehydration experiments of talc and 10 Å phase coupled with in situ measurement of reaction kinetics using synchrotron X-ray diffraction. Newly developed, X-ray transparent, pressure-sealed, titanium capsule ensured a closed thermochemical environment. From isothermal kinetics data fitted to the Avrami's equation and from the texture of reaction products, we conclude that dehydration rates of these minerals are limited by diffusion. Predicted minimum rates of fluid release range from 10 - 4 to 9 × 10 - 6 m 3fluid m - 3 rock s - 1 , and are fast enough to provoke hydraulic rupture since Maxwell relaxation rate of rocks relevant of subduction zones are slower than the rate of fluid release. These rates are comparable between talc, 10 Å phase and antigorite also [Perrillat, J.-P., Daniel, I., Koga, K.T., Reynard, B., Cardon, H., Crichton, W.A., 2005. Kinetics of antigorite dehydration: a real-time X-ray diffraction study. Earth Planet. Sci. Lett. 236, 899-913]. Consequently, we suggest that the dehydration of hydrous minerals may eventually be fast enough to trigger the intermediate-depth earthquakes, and that the deepest among intermediate-depth earthquakes may actually locate the limits for dehydration of hydrous minerals in the downgoing lithosphere.

  12. Geochemistry of subalkaline and alkaline extrusives from the Kermanshah ophiolite, Zagros Suture Zone, Western Iran: implications for Tethyan plate tectonics

    NASA Astrophysics Data System (ADS)

    Ghazi, A. Mohamad; Hassanipak, A. A.

    1999-06-01

    The Kermanshah ophiolite is a highly dismembered ophiolite complex that is located in western Iran and belongs to the Zagros orogenic system. The igneous rocks of this complex consist of both mantle and crustal suites and include peridotites (dunite and harzburgite), cumulate gabbros, diorites, and a volcanic sequence that exhibits a wide range in composition from subalkaline basalts to alkaline basalts to trachytes. The associated sedimentary rocks include a variety of Upper Triassic to Lower Cretaceous deep- and shallow-water sedimentary rocks (e.g., dolomite, limestone, and pelagic sediments, including umber). Also present are extensive units of radiolarian chert. The geochemical data clearly identifies some of the volcanic rocks to have formed from two distinct types of basaltic melts: (i) those of the subalkaline suite, which formed from an initial melt with a light rare earth elements (LREE) enriched signature and incompatible trace element patterns that suggest an island arc affinity; and (ii) those of the alkaline suite with LREE-enriched signature and incompatible trace element patterns that are virtually identical to typical oceanic island basalt (OIB) pattern. The data also suggests that the trachytes were derived from the alkaline source, with fractionation controlled by extensive removal of plagioclase and to a lesser extent clinopyroxene. The presence of compositionally diverse volcanics together with the occurrence of a variety of Triassic-Cretaceous sedimentary rocks and radiolarian chert indicate that the studied volcanic rocks from the Kermanshah ophiolite represent off-axis volcanic units that were formed in intraplate oceanic island and island arc environments in an oceanic basin. They were located on the eastern and northern flanks of one of the spreading centers of a ridge-transform fault system that connected Troodos to Oman prior to its subduction under the Eurasian plate.

  13. Accurate measurements of vadose zone fluxes using automated equilibrium tension plate lysimeters: A synopsis of results from the Spydia research facility, New Zealand.

    NASA Astrophysics Data System (ADS)

    Wöhling, Thomas; Barkle, Greg; Stenger, Roland; Moorhead, Brian; Wall, Aaron; Clague, Juliet

    2014-05-01

    Automated equilibrium tension plate lysimeters (AETLs) are arguably the most accurate method to measure unsaturated water and contaminant fluxes below the root zone at the scale of up to 1 m². The AETL technique utilizes a porous sintered stainless-steel plate to provide a comparatively large sampling area with a continuously controlled vacuum that is in "equilibrium" with the surrounding vadose zone matric pressure to ensure measured fluxes represent those under undisturbed conditions. This novel lysimeter technique was used at an intensive research site for investigations of contaminant pathways from the land surface to the groundwater on a sheep and beef farm under pastoral land use in the Tutaeuaua subcatchment, New Zealand. The Spydia research facility was constructed in 2005 and was fully operational between 2006 and 2011. Extending from a central access caisson, 15 separately controlled AETLs with 0.2 m² surface area were installed at five depths between 0.4 m and 5.1 m into the undisturbed volcanic vadose zone materials. The unique setup of the facility ensured minimum interference of the experimental equipment and external factors with the measurements. Over the period of more than five years, a comprehensive data set was collected at each of the 15 AETL locations which comprises of time series of soil water flux, pressure head, volumetric water contents, and soil temperature. The soil water was regularly analysed for EC, pH, dissolved carbon, various nitrogen compounds (including nitrate, ammonia, and organic N), phosphorus, bromide, chloride, sulphate, silica, and a range of other major ions, as well as for various metals. Climate data was measured directly at the site (rainfall) and a climate station at 500m distance. The shallow groundwater was sampled at three different depths directly from the Spydia caisson and at various observation wells surrounding the facility. Two tracer experiments were conducted at the site in 2009 and 2010. In the 2009

  14. Wind loads on flat plate photovoltaic array fields. Phase III, final report

    SciTech Connect

    Miller, R.D.; Zimmerman, D.K.

    1981-04-01

    The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads.

  15. Subduction zones beneath Indonesia imaged by Rayleigh wave phase velocity tomography

    NASA Astrophysics Data System (ADS)

    Liu, F.; Yang, T.; Harmon, N.

    2013-12-01

    Situated at the junction of several tectonic plates including Indian-Australia, Eurasia, and Philippine Sea, the Indonesian archipelago is one of the most tectonically complex regions on earth with subductions, collisions and accretions occurring along and within its boundaries. A high-resolution lithospheric and upper mantle model, therefore, is needed to understand these complex processes beneath this region. We present a phase velocity model derived from teleseismic Rayleigh waves recorded at seismic stations in this region. We use the modified version of the two-plane wave tomography, in which the non-planar effects of surface wave propagation such as multipathing and scattering are accounted for by two plane wave interference and using of finite frequency kernels. We measure the amplitudes and phases at 16 individual periods ranging from 20s to 150s for the fundamental mode of Rayleigh waves at over 30 stations. 254 earthquakes are selected from global events greater than Ms 5.5 in the distance range of 25°- 150°. To account for the wavefield inconsistencies among stations for each earthquake due to the large scale of our study region, we divide the seismic array into 4 groups of stations in the two-plane wave parameter inversion. The phase velocity maps from our preliminary results show coherent features between adjacent periods. The most dominant structure in phase velocity maps for all periods is the strong fast-velocity belts beneath Sunda Trench, Java Trench, Timor Trough and the trenches around Celebes Sea, which shift gradually toward the subduction directions. The strength of the high velocity anomaly varies among trenches, likely suggesting the different age of subducting slabs. In addition, a velocity contrast in the middle of Borneo appears to mark the Lupar Line, a boundary between the stable Sundaland continental core and fragments of ophiolitic and Asian continental material accreted to Borneo during the Cretaceous. The 3-D shear wave structure

  16. Analysis of thermoelastic dissipation in circular micro-plate resonators using the generalized thermoelasticity theory of dual-phase-lagging model

    NASA Astrophysics Data System (ADS)

    Guo, F. L.; Song, J.; Wang, G. Q.; Zhou, Y. F.

    2014-05-01

    This study investigates the thermoelastic dissipation of micro-plate resonators by using the generalized thermoelasticity theory of dual-phase-lagging model. Explicit formulae of thermoelastic damping and frequency shift are derived. Influences of the plate thickness and vibration frequency on the thermoelastic damping are examined. Phenomena distinct from those of classical theory are observed in the numerical results of thermoelastic damping in micro-plate resonators. These results may bring new insights into the study of thermoelastic damping at submicrometer or nanometer scale.

  17. Nankai ACORK Tidel Response: Phase Lead/Delay as a Potential Indicator for Fracture Zones?

    NASA Astrophysics Data System (ADS)

    Kinoshita, M.; Kano, Y.

    2014-12-01

    For more than 12 years we have been conducting a continuous monitoring of downhole pore pressures at multiple sub-bottom intervals in ODP Holes 808I and 1173B situated landward and seaward of the deformation front in the Nankai Trough off Cape Muroto. We found that the pressure response to the semi-diurnal ocean tide (M2), both amplitude and phase, gradually changed during the observed period. The M2 amplitudes at most depths in Hole 808I decay as their phase delay (up to 45 degrees), only if the amplitude is larger than ~0.2 of that for the seafloor. On the other hand, we observe an anomalous phase lead (up to -40 degrees) if the relative amplitude is smaller than ~0.2. We hypothesize that the recorded pore pressure is a combination of two components; one with larger amplitudes and phase-delay and the other with small amplitude and phase-lead. The former is interpreted to be caused by a direct communication between sensors and the seafloor through the space of the annulus. It gradually attenuated by the decrease in hydraulic diffusivity around the sensors, as the annulus space is packed off by a gradual collapsing of the formation. After that, we hypothesize that the sensor is in good mechanical/hydrological contact with the formation, and that the latter variation is identical or close to that of formation pressure variation. The mechanism of the latter variation remains enigmatic, but a feasible explanation is the existence of a layer, next to the sensor, with the contrast in fluid bulk modulus, frame bulk modulus, or permeability (Wang and Davis, 1996). At Site 808, numerous small fractures were detected in cores/logs, which can generate such contrast in bulk modulus or permeability. Other causes, such as solid earth tide or thermal expansion/contraction caused by a tidally-induced flow within the casing cannot explain both the amplitude and phase simultaneously. We propose that a tidal response signal can be used to detect local fracture zones or gas

  18. Leukaemic phase of mantle zone (intermediate) lymphoma: its characterisation in 11 cases.

    PubMed Central

    De Oliveira, M S; Jaffe, E S; Catovsky, D

    1989-01-01

    Sixteen patients presented with B cell leukaemia (white cell count 26-269 x 10(9)/l) which could not be classified as chronic lymphocytic (CLL), prolymphocytic leukaemia, or follicular lymphoma in leukaemic phase. Eleven patients (10 men, one woman) corresponded histologically to intermediate (INT) or mantle zone lymphoma, and five, with less well defined features, were designated small lymphocytic lymphoma with cleaved cells. The blood films showed a pleomorphic picture with lymphoid cells of predominantly medium size with nuclear irregularities and clefts. The membrane phenotype of the circulating cells showed strong immunoglobulin staining and reactivity with CD5 and FMC7 in all cases tested; CD10 was positive in six out of nine cases. The membrane phenotype of two of the five cases of small lymphocytic lymphoma was close to those of B-CLL and three resembled INT lymphoma. Bone marrow trephine biopsy specimens showed a diffuse pattern of infiltration in INT lymphoma. The median survival of these patients was less than two years, suggesting that a leukaemic presentation is associated with poor prognosis. By combining data from histology, membrane markers, and peripheral blood morphology, the leukaemic phase of typical INT lymphoma can be defined in most cases. Images PMID:2794086

  19. Phase transformations during the Ag-In plating and bonding of vertical diode elements of multijunction solar cells

    SciTech Connect

    Klochko, N. P. Khrypunov, G. S.; Volkova, N. D.; Kopach, V. R.; Lyubov, V. N.; Kirichenko, M. V.; Momotenko, A. V.; Kharchenko, N. M.; Nikitin, V. A.

    2013-06-15

    The conditions of the bonding of silicon multijunction solar cells with vertical p-n junctions using Ag-In solder are studied. The compositions of electrodeposited indium films on silicon wafers silver plated by screen printing and silver and indium films fabricated by layer-by-layer electrochemical deposition onto the surface of silicon vertical diode cells silver plated in vacuum are studied. Studying the electrochemical-deposition conditions, structure, and surface morphology of the grown layers showed that guaranteed bonding is provided by 8-min heat treatment at 400 Degree-Sign C under the pressure of a stack of metallized silicon wafers; however, the ratio of the indium and silver layer thicknesses should not exceed 1: 3. As this condition is satisfied, the solder after wafer bonding has the InAg{sub 3} structure (or InAg{sub 3} with an Ag phase admixture), due to which the junction melting point exceeds 700 Degree-Sign C, which guarantees the functioning of such solar cells under concentrated illumination.

  20. Morphological Evolution of Electrochemically Plated/Stripped Lithium Microstructures Investigated by Synchrotron X-ray Phase Contrast Tomography.

    PubMed

    Sun, Fu; Zielke, Lukas; Markötter, Henning; Hilger, André; Zhou, Dong; Moroni, Riko; Zengerle, Roland; Thiele, Simon; Banhart, John; Manke, Ingo

    2016-08-23

    Due to its low redox potential and high theoretical specific capacity, Li metal has drawn worldwide research attention because of its potential use in next-generation battery technologies such as Li-S and Li-O2. Unfortunately, uncontrollable growth of Li microstructures (LmSs, e.g., dendrites, fibers) during electrochemical Li stripping/plating has prevented their practical commercialization. Despite various strategies proposed to mitigate LmS nucleation and/or block its growth, a fundamental understanding of the underlying evolution mechanisms remains elusive. Herein, synchrotron in-line phase contrast X-ray tomography was employed to investigate the morphological evolution of electrochemically deposited/dissolved LmSs nondestructively. We present a 3D characterization of electrochemically stripped Li electrodes with regard to electrochemically plated LmSs. We clarify fundamentally the origin of the porous lithium interface growing into Li electrodes. Moreover, cleavage of the separator caused by growing LmS was experimentally observed and visualized in 3D. Our systematic investigation provides fundamental insights into LmS evolution and enables us to understand the evolution mechanisms in Li electrodes more profoundly. PMID:27463258

  1. CMS Resistive Plate Chamber overview, from the present system to the upgrade phase I

    NASA Astrophysics Data System (ADS)

    Paolucci, P.; Hadjiiska, R.; Litov, L.; Pavlov, B.; Petkov, P.; Dimitrov, A.; Beernaert, K.; Cimmino, A.; Costantini, S.; Guillaume, G.; Lellouch, J.; Marinov, A.; Ocampo, A.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Verwilligen, P.; Yazgan, E.; Zaganidis, N.; Aleksandrov, A.; Genchev, V.; Iaydjiev, P.; Rodozov, M.; Shopova, M.; Sultanov, G.; Ban, Y.; Cai, J.; Xue, Z.; Ge, Y.; Li, Q.; Qian, S.; Avila, C.; Chaparro, L. F.; Gomez, J. P.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Assran, Y.; Sharma, A.; Abbrescia, M.; Colaleo, A.; Pugliese, G.; Loddo, F.; Calabria, C.; Maggi, M.; Benussi, L.; Bianco, S.; Colafranceschi, S.; Piccolo, D.; Carrillo, C.; Iorio, O.; Buontempo, S.; Vitulo, P.; Berzano, U.; Gabusi, M.; Kang, M.; Lee, K. S.; Park, S. K.; Shin, S.; Kim, M. S.; Seo, H. K.; Goh, J.; Choi, Y.-I.

    2013-04-01

    Resistive Plate Chambers have been chosen as dedicated trigger muon detector for the Compact Muon Solenoid experiment [1] at the Large Hadron Collider [2] at CERN. The system consists of about 3000 m2 of double gap RPC chambers placed in both the barrel and endcap muon regions. About 5.6 fb-1 (2010-2011) of proton-proton collision data have been used to study the performance of the RPC detector and trigger. A full high voltage scan of all the RPC chambers has been done at beginning of 2011 data taking to evaluate the working point chamber by chamber and to eventually spot aging effects. The excellent behaviour of the RPC detector can be summarized with an average detector efficiency of about 97%, an average cluster size of 1.8 and an intrinsic noise rate of 0.1 Hz/cm2. This is a clear fulfilment of all the requirements decided 18 years ago in the CMS TDR document [3].

  2. Offshore double-planed shallow seismic zone in the NE Japan forearc region revealed by sP depth phases recorded by regional networks

    NASA Astrophysics Data System (ADS)

    Gamage, Shantha S. N.; Umino, Norihito; Hasegawa, Akira; Kirby, Stephen H.

    2009-07-01

    We detected the sP depth phase at small epicentral distances of about 150 km or more in the seismograms of shallow earthquakes in the NE Japan forearc region. The focal depths of 1078 M > 3 earthquakes that occurred from 2000 to 2006 were precisely determined using the time delay of the sP phase from the initial P-wave arrival. The distribution of relocated hypocentres clearly shows the configuration of a double-planed shallow seismic zone beneath the Pacific Ocean. The upper plane has a low dip angle near the Japan Trench, increasing gradually to ~30° at approximately 100 km landward of the Japan Trench. The lower plane is approximately parallel to the upper plane, and appears to be the near-trench counterpart of the lower plane of the double-planed deep seismic zone beneath the land area. The distance between the upper and lower planes is 28-32 km, which is approximately the same as or slightly smaller than that of the double-planed deep seismic zone beneath the land area. Focal mechanism solutions of the relocated earthquakes are determined from P-wave initial motion data. Although P-wave initial motion data for these offshore events are not ideally distributed on the focal sphere, we found that the upper-plane events that occur near the Japan Trench are characterized by normal faulting, whereas lower-plane events are characterized by thrust faulting. This focal mechanism distribution is the opposite to that of the double-planed deep seismic zone beneath the land area. The characteristics of these focal mechanisms for the shallow and deep doubled-planed seismic zones can be explained by a bending-unbending model of the subducting Pacific plate. Some of relocated earthquakes took place in the source area of the 1933 Mw8.4 Sanriku earthquake at depths of 10-23 km. The available focal mechanisms for these events are characterized by normal faulting. Given that the 1933 event was a large normal-fault event that occurred along a fault plane dipping landward, the

  3. Offshore double-planed shallow seismic zone in the NE Japan forearc region revealed by sP depth phases recorded by regional networks

    USGS Publications Warehouse

    Gamage, S.S.N.; Umino, N.; Hasegawa, A.; Kirby, S.H.

    2009-01-01

    We detected the sP depth phase at small epicentral distances of about 150 km or more in the seismograms of shallow earthquakes in the NE Japan forearc region. The focal depths of 1078 M > 3 earthquakes that occurred from 2000 to 2006 were precisely determined using the time delay of the sP phase from the initial P-wave arrival. The distribution of relocated hypocentres clearly shows the configuration of a double-planed shallow seismic zone beneath the Pacific Ocean. The upper plane has a low dip angle near the Japan Trench, increasing gradually to ???30?? at approximately 100 km landward of the Japan Trench. The lower plane is approximately parallel to the upper plane, and appears to be the near-trench counterpart of the lower plane of the double-planed deep seismic zone beneath the land area. The distance between the upper and lower planes is 28-32 km, which is approximately the same as or slightly smaller than that of the double-planed deep seismic zone beneath the land area. Focal mechanism solutions of the relocated earthquakes are determined from P-wave initial motion data. Although P-wave initial motion data for these offshore events are not ideally distributed on the focal sphere, we found that the upper-plane events that occur near the Japan Trench are characterized by normal faulting, whereas lower-plane events are characterized by thrust faulting. This focal mechanism distribution is the opposite to that of the double-planed deep seismic zone beneath the land area. The characteristics of these focal mechanisms for the shallow and deep doubled-planed seismic zones can be explained by a bending-unbending model of the subducting Pacific plate. Some of relocated earthquakes took place in the source area of the 1933 Mw8.4 Sanriku earthquake at depths of 10-23 km. The available focal mechanisms for these events are characterized by normal faulting. Given that the 1933 event was a large normal-fault event that occurred along a fault plane dipping landward, the

  4. On gravity from SST, geoid from Seasat, and plate age and fracture zones in the Pacific. [Satellite-to-Satellite Tracking

    NASA Technical Reports Server (NTRS)

    Marsh, B. D.; Marsh, J. G.; Williamson, R. G.

    1984-01-01

    Data from an additional 50 satellite-to-satellite tracking (SST) passes were combined with earlier measurements of the high degree and order (n, m, 12) gravity in the central Pacific. A composite map was produced which shows good agreement with conventional GEM models. Data from the Seasat altimeter was reduced and found to agree well with both the SST and the GEM fields. The maps are dominated especially in the east, by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Further comparison with regional bathymetric data shows a remarkably close correlation with plate age. Each anomaly band is framed by those major fracture zones having large offsets. The regular spacing of these fractures seems to account for the fabric in the gravity fields. Other anomalies are accounted for by hot spots. The source of part of these anomalies is in the lithosphere itself. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantle without complete thermal equilibration is considered. Previously announced in STAR as N84-11559

  5. Relocating Seismicity on the Arctic Plate Boundary Using Teleseismic and Regional Phases and a Bayesian Multiple Event Locator

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Dahl-Jensen, Trine; Kværna, Tormod; Larsen, Tine B.; Paulsen, Berit; Voss, Peter

    2016-04-01

    The tectonophysics of plate boundaries are illuminated by the pattern of seismicity - and the ability to locate seismic events accurately depends upon the number and quality of observations, the distribution of recording stations, and how well the traveltimes of seismic phases are modelled. The boundary between the Eurasian and North American plates between 70 and 84 degrees North hosts large seismic events which are well recorded teleseismically and many more events at far lower magnitudes that are well recorded only at regional distances. Existing seismic bulletins have considerable spread and bias resulting from limited station coverage and deficiencies in the velocity models applied; this is particularly acute for the lower magnitude events which may only be constrained by a small number of Pn and Sn arrivals. Over the past 15 years, there has been a significant improvement in the seismic network in the Arctic - a difficult region to instrument due to the harsh climate, a sparsity of quiet and accessible sites, and the expense and difficult logistics of deploying and maintaining stations. New deployments and upgrades to stations on Greenland, Svalbard, and the islands Jan Mayen, Hopen, and Bjørnøya have resulted in a sparse but stable regional seismic network which results in events down to magnitudes below 3 generating high quality Pn and Sn signals on multiple stations. A catalog of over 1000 events in the region since 1998 has been generated using many new phase readings on stations on both sides of the spreading ridge in addition to teleseismic P phases. The Bayesloc program, a Bayesian hierarchical multiple event location algorithm, has been used to relocate the full set of events iteratively and this has resulted in a significant reduction in the spread in hypocenter estimates for both large and small events. Whereas single event location algorithms minimize the vector of time residuals on an event-by-event basis, Bayesloc favours the hypocenters which

  6. SCREENING MODEL FOR NONAQUEOUS PHASE LIQUID TRANS- PORT IN THE VADOSE ZONE USING GREEN-AMPT AND KINEMATIC WAVE THEORY

    EPA Science Inventory

    In this paper, a screening model for flow of a nonaqueous phase liquid (NAPL) and associated chemical transport in the vadose zone is developed. The model is based on kinematic approximation of the governing equations for both the NAPL and a partitionable chemical constituent. Th...

  7. SCREENING MODEL FOR NONAQUEOUS PHASE-LIQUID TRANSPORT IN THE VADOSE ZONE USING GREEN-AMPT AND KINEMATIC WAVE THEORY

    EPA Science Inventory

    In this paper, a screening model for flow of a nonaqueous phase liquid (NAPL) and associated chemical transport in the vadose zone is developed. he model is based on kinematic approximation of the governing equations for both the NAPL and a partitionable chemical constituent. he ...

  8. Lu-Hf garnet geochronology applied to plate boundary zones: Insights from the (U)HP terrane exhumed within the Woodlark Rift

    NASA Astrophysics Data System (ADS)

    Zirakparvar, N. A.; Baldwin, S. L.; Vervoort, J. D.

    2011-09-01

    High-pressure and ultra high-pressure (U)HP metamorphic rocks occur in many of the world's major orogenic belts, suggesting that subduction of continental lithosphere is a geologically important process. Despite the widespread occurrence of these rocks, relatively little is known about the timescales associated with (U)HP metamorphism. This is because most (U)HP terranes are tectonically overprinted and juxtaposed against rocks with a different history. An exception to this are the Late Miocene (U)HP metamorphic rocks found in active metamorphic core complexes (MCC) in the Woodlark Rift of southeastern Papua New Guinea. This region provides a rare opportunity to study the garnet Lu-Hf isotopic record of (U)HP metamorphism in a terrane that is not tectonically overprinted. In order to constrain the timing of garnet growth relative to the history of (U)HP metamorphism and the evolution of the Woodlark Rift, Lu-Hf ages were determined, in conjunction with measurements of Lu and major element zoning, for garnets from three metamorphic rocks. Garnets from the three samples yielded different ages that, instead of recording the spatial and temporal evolution associated with a single metamorphic event, provide information on the timing of three separate plate boundary events. The youngest Lu-Hf age determined was 7.1 ± 0.7 Ma for garnets in a Late Miocene coesite eclogite. The age is interpreted to record the time when a garnet-bearing partial melt of the mantle crystallized within subducted continental lithosphere at (U)HP conditions. The young Lu-Hf age from the coesite eclogite is in contrast to a 68 ± 3.6 Ma Lu-Hf age obtained on large (1-2 cm) garnet porphyroblasts, from within the Pleistocene amphibolite facies shear zone carapace bounding exposures of (U)HP rocks in the D'Entrecasteaux Islands. This older age records the growth of garnet in response to continental subduction and ophiolite obduction in the region north and east of Australia during late Mesozoic

  9. Insights into a fossil plate interface of an erosional subduction zone: a tectono-metamorphic study of the Tianshan metamorphic belt.

    NASA Astrophysics Data System (ADS)

    Bayet, Lea; Moritz, Lowen; Li, Jilei; Zhou, Tan; Agard, Philippe; John, Timm; Gao, Jun

    2016-04-01

    Subduction zone seismicity and volcanism are triggered by processes occurring at the slab-wedge interface as a consequence of metamorphic reactions, mass-transfer and deformation. Although the shallow parts of subduction zones (<30-40 km) can be partly accessed by geophysical methods, the resolution of these techniques is insufficient to characterize and image the plate interface at greater depths (>60km). In order to better understand the plate interface dynamics at these greater depths, one has to rely on the rock record from fossil subduction zones. The Chinese Tianshan metamorphic belt (TMB) represents an ideal candidate for such studies, because structures are well exposed with exceptionally fresh high-pressure rocks. Since previous studies from this area focused on fluid-related processes and its metamorphic evolution was assessed on single outcrops, the geodynamic setting of this metamorphic belt is unfortunately heavily debated. Here, we present a new geodynamic concept for the TMB based on detailed structural and petrological investigations on a more regional scale. A ~11km x 13km area was extensively covered, together with E-W and N-S transects, in order to produce a detailed map of the TMB. Overall, the belt is composed of two greenschist-facies units that constitute the northern and southern border of a large high-pressure (HP) to ultra high-pressure (UHP) unit in the center. This HP-UHP unit is mainly composed of metasediments and volcanoclastic rocks, with blueschist, eclogite and carbonate lenses. Only the southern part of the HP-UHP unit is composed of the uppermost part of an oceanic crust (e.g., pillow basalts and deep-sea carbonates). From south to north, the relative abundance and size of blueschist massive boudins and layers (as well as eclogite boudins) decreases and the sequence is increasingly interlayered with metasedimentary and carbonate-rich horizons. This indicates that the subducted material was dominated by trench filling made of

  10. Bandwidth characteristics for the stepped conical-zoned antenna

    NASA Astrophysics Data System (ADS)

    Wiltse, James C.

    2002-07-01

    The stepped conical zoned lens antenna has better overall efficiency than a true lens, and provides an excellent antenna pattern. It also exhibits somewhat different bandwidth characteristics than the Fresnel zone plate antenna. This paper examines the frequency behavior in detail, particularly for microwave and millimeter-wave applications. For the usual zone plate antenna employed at microwave or millimeter wavelengths, path length adjustment (i.e., phase correction) is accomplished by cutting different depths (grooves) in a dielectric plate or by using two or more dielectrics having different dielectric constants. The new design uses a tilted cut in a flat dielectric plate, which more accurately matches the shape of a true lens and produces much lower phase error. The construction is still linear (i.e. spherical or hyperboloidal curves do not have to be cut), and can be made, for example, by a milling machine with a tilted bit. For a circular zone plate, the lens is a stepped conical shape. The phase correction steps are small, usually a few degrees, which is much smaller than for the typical Fresnel zone plate. The bandwidth characteristics are calculated for specific cases.

  11. The impact of an efficient collection sites location on the zoning phase in municipal solid waste management

    SciTech Connect

    Ghiani, Gianpaolo Manni, Andrea Manni, Emanuele Toraldo, Massimiliano

    2014-11-15

    Highlights: • We study the problems of locating collection areas and zoning the service territory in a municipal waste management system. • We investigate the impact that an efficient collection sites location has on the subsequent zoning phase. • On a real-world test case, we show that the proposed approach could allow achieving significant monetary savings. - Abstract: In this paper, we study two decisional problems arising when planning the collection of solid waste, namely the location of collection sites (together with bin allocation) and the zoning of the service territory, and we assess the potential impact that an efficient location has on the subsequent zoning phase. We first propose both an exact and a heuristic approach to locate the unsorted waste collection bins in a residential town, and to decide the capacities and characteristics of the bins to be located at each collection site. A peculiar aspect we consider is that of taking into account the compatibility between the different types of bins when allocating them to collection areas. Moreover, we propose a fast and effective heuristic approach to identify homogeneous zones that can be served by a single collection vehicle. Computational results on data related to a real-life instance show that an efficient location is fundamental in achieving consistent monetary savings, as well as a reduced environmental impact. These reductions are the result of one vehicle less needed to perform the waste collection operations, and an overall traveled distance reduced by about 25% on the average.

  12. A New Arabia-Africa-Eurasia GPS Velocity Field (1994-2014) and E Mediterranean Block Model: Implications for Continental Deformation in a Zone of Active Plate Interaction

    NASA Astrophysics Data System (ADS)

    Vernant, P.; Floyd, M.; Ozener, H.; Ergintav, S.; Karakhanian, A.; Kadirov, F. A.; Sokhadze, G.; ArRajehi, A.; Nankali, H. R.; Georgiev, I.; Ganas, A.; Paradissis, D.; McClusky, S.; Gomez, F. G.; Reilinger, R. E.

    2014-12-01

    We present new GPS velocities for the Arabia-Africa-Eurasia region determined with GAMIT/GLOBK (>830 velocities) spanning the period 1994-2014. Here we consider the E Mediterranean region of plate interaction. We use DEFNODE software to develop block models and estimate slip rates on major faults and strain of some blocks. The wrms of residual velocities from our new model is 1.3 mm/yr. We identify small E-W extension within the newly defined Anatolian block confined to a 100-200 km wide zone south of the North Anatolian Fault (NAF) reaching 2-3 mm/yr with rates increasing towards the west. Possible causes we consider include, un-modeled postseismic effects of the 1999 Izmit/Duzce earthquake sequence, continuing post-seismic effects of the 20th Century sequence of M>7 earthquakes, and/or toroidal sub-lithospheric flow towards the subducting Hellenic slab. The overall strain rate of the Marmara Sea block is dominantly N-S extension, and the Van block, N-S compression. Present slip rates along the NAF increase from E to W, 22-24 mm/yr along the E to E-central segment and 27-28 mm/yr along the W segment. We quantify extension in the G. of Corinth, central Greece, and G. of Evia; the W, central and E sections of the Hellenic Trench are shortening with extension in the back-arc. The W Hellenic Trench and W Peloponnese have right-lateral strike-slip and the E Hellenic Trench, left-lateral ss. N-S extension (2-4 mm/yr) in N Greece and the N Aegean Sea extends at least to 42°N. Arabia-Sinai left-lateral motion across the Dead Sea Fault is ~5 mm/yr along the S segment; significant residual velocities along the N and S segments indicate lower slip rates in the N and require fault segmentation to account for slip rate variations along strike. We identify E-W contraction of the Arabian (Persian) Gulf (~3-5 mm/yr) that extends into the E part of the Arabian Plate. We will quantify and present these and other observed deformation patterns and discuss their tectonic implications.

  13. Investigation of residual stresses in a multipass weld in 1 in. stainless steel plate

    SciTech Connect

    Spooner, S.; Fernandez Baca, J.A.; David, S.A.; Hubbard, C.R.; Holden, T.M.; Root, J.H.

    1994-06-01

    Residual stresses and strains were measured in two welded 25-mm thick plates of type 304 stainless steel by the neutron diffraction. The filler metal was type 308 stainless steel and the weld zone had a two phase microstructure in which the austenitic phase lattice parameter differs from the base metal. In these circumstances stain-free samples were taken from the weld zone area for analysis of the lattice parameters and ferrite content using neutron powder diffraction. Corrections for lattice parameter variation were applied permitting the calculation of residual strains and stresses in weld zone, heat affected zone (HAZ) and base metal. One of the two welds was examined without stress relief and the other was given a stress relief treatment consisting of vibration at a frequency below the resonant condition dudng welding. In both plates the largest residual stress component (longitudinal) is found in the fusion zone near the boundary between the weld zone and the heat affected zone. This longitudinal component is 400 {plus_minus} 50 MPa in tension. The normal stresses are generally close to zero although large fluctuations are found in the weld zone. The transverse stresses are as high as 200 MPa in the weld zone and decrease to 50 MPa {plus_minus} 40 MPa. The lattice parameter variation was equivalent to 5 {times} l0{minus}4 compressive strain and the ferrite content approached 9 percent at the center of the weld zone. Variations in residual stresses with thickness through the base metal plate were small. The treated plate and untreated plate showed nearly identical patterns of stress distribution. Differences in the measured stresses between vibratory-stress-relief treated and untreated plates fall within error bars of the stress determination in these particular 25 mm thick 300-type stainless steel plates.

  14. Quantitative phase retrieval with arbitrary pupil and illumination

    DOE PAGESBeta

    Claus, Rene A.; Naulleau, Patrick P.; Neureuther, Andrew R.; Waller, Laura

    2015-10-02

    We present a general algorithm for combining measurements taken under various illumination and imaging conditions to quantitatively extract the amplitude and phase of an object wave. The algorithm uses the weak object transfer function, which incorporates arbitrary pupil functions and partially coherent illumination. The approach is extended beyond the weak object regime using an iterative algorithm. Finally, we demonstrate the method on measurements of Extreme Ultraviolet Lithography (EUV) multilayer mask defects taken in an EUV zone plate microscope with both a standard zone plate lens and a zone plate implementing Zernike phase contrast.

  15. Tight focusing of a higher-order radially polarized beam transmitting through multi-zone binary phase pupil filters.

    PubMed

    Guo, Hanming; Weng, Xiaoyu; Jiang, Man; Zhao, Yanhui; Sui, Guorong; Hu, Qi; Wang, Yang; Zhuang, Songlin

    2013-03-11

    When the pupil filters are used to improve the performance of the imaging system, the conversion efficiency is a critical characteristic for real applications. Here, in order to take full advantage of the subwavelength focusing property of the radially polarized higher-order Laguerre-Gaussian (LG) beam, we introduce the multi-zone binary phase pupil filters into the imaging system to deal with the problem that the focal spot is split along the z axis for the small size parameter of the incident LG beam. We provide an easy-to-perform procedure for the design of multi-zone binary phase pupil filters, where the zone numbers of π phase are uncertain when the optimizing procedure starts. Based on this optimizing procedure, we successfully find the set of optimum structures of a seventeen-belt binary phase pupil filters and generate the excellent focal spot, where the depth of focus, the focal spot transverse size, the Strehl ratio, and the sidelobe intensity are 9.53λ, 0.41λ, 41.75% and 16.35% in vacuum, respectively. Most importantly, even allowing the power loss of the incident LG beam truncated by the pupil of the imaging system, the conversion efficiency is still as high as 37.3%. Theoretical calculations show that we succeed to have sufficient conversion efficiency while utilizing the pupil filters to decrease the focal spot and extend the depth of focus. PMID:23482107

  16. Wide injection zone compression in gradient reversed-phase liquid chromatography.

    PubMed

    Gilar, Martin; McDonald, Thomas S; Johnson, Jay S; Murphy, James P; Jorgenson, James W

    2015-04-17

    Chromatographic zone broadening is a common issue in microfluidic chromatography, where the sample volume introduced on column often exceeds the column void volume. To better understand the propagation of wide chromatographic zones on a separation device, a series of MS Excel spreadsheets were developed to simulate the process. To computationally simplify these simulations, we investigated the effects of injection related zone broadening and its gradient related zone compression by tracking only the movements of zone boundaries on column. The effects of sample volume, sample solvent, gradient slope, and column length on zone broadening were evaluated and compared to experiments performed on 0.32mm I.D. microfluidic columns. The repetitive injection method (RIM) was implemented to generate experimental chromatograms where large sample volume scenarios can be emulated by injecting two discrete small injection plugs spaced in time. A good match between predicted and experimental RIM chromatograms was observed. We discuss the performance of selected retention models on the accuracy of predictions and use the developed spreadsheets for illustration of gradient zone focusing for both small molecules and peptides. PMID:25748538

  17. Seismic coupling and uncoupling at subduction zones

    NASA Technical Reports Server (NTRS)

    Ruff, L.; Kanamori, H.

    1983-01-01

    Some of the correlations concerning the properties of subduction zones are reviewed. A quantitative global comparison of many subduction zones reveals that the largest earthquakes occur in zones with young lithosphere and fast convergence rates. Maximum earthquake size is directly related to the asperity distribution on the fault plane. This observation can be translated into a simple model of seismic coupling where the horizontal compressive stress between two plates is proportional to the ratio of the summed asperity area to the total area of the contact surface. Plate age and rate can control asperity distribution directly through the horizontal compressive stress associated with the vertical and horizontal velocities of subducting slabs. The basalt to eclogite phase change in the down-going oceanic crust may be largely responsible for the uncoupling of subduction zones below a depth of about 40 km.

  18. [Unsolved radioecological problems of Chernobyl NPP Exclusion Zone at late phase of the accident].

    PubMed

    Ivanov, Iu A; Bondar'kov, M D

    2009-01-01

    Some scientific and scientific-industrial radioecological problems of Chernobyl NPP Exclusion Zone are considered. These problems are demanding its solution or development of already obtaining results for adequate understanding and planning of conducted researches as well as for decision support of activities directed to minimization of the accident consequences. Following problems are discussed: an estimation of radiological significance of natural and technogenic objects of the Zone, long-term dynamics of radioecological processes, autorehabilitation processes of the Zone ecosystems, complex estimation of the influence of the Zone technogenic objects to radioecological state of ecosystems, radioecology of urban ecosystems (by the example of former town Pripyat) and problems of rehabilitation of abandoned areas. PMID:19637738

  19. Reflected and mode-converted seismic waves within the shallow aleutian subduction zone, southern Kenai Peninsula, Alaska

    USGS Publications Warehouse

    Stephens, C.D.; Page, R.A.; Lahr, J.C.

    1990-01-01

    Pronounced secondary phases observed in local recordings of quarry shots and earthquakes on the southern Kenai Peninsula are identified as reflected P and S and converted S-to-P phases originating within four depth ranges: in the upper few kilometers of the Cook Inlet Tertiary basin, at midcrustal depths within the overthrust North American plate, at about 35 km depth near the top of the Wadati-Benioff seismic zone in proximity to the inferred interplate megathrust, and at about 5-10 km below the megathrust in the subducted Pacific plate. The positions and origins of the mid-upper plate (MUP) discontinuity and similar reflectors are discussed. It appears the the MUP discontinuity is seismically inactive and does not represent a brittle-ductile transition zone within the upper plate. The two converted S-to-P phases generated near the top of the subducted plate could indicate a low velocity zone associated with subducted oceanic crust. -after Authors

  20. Caribbean plate interactions

    SciTech Connect

    Ball, M. )

    1993-02-01

    Vector analysis of plate motions, derived from studies of Atlantic magnetic lineations and fracture zone trends, indicates the following relative movements between the Caribbean, North American, and South American Plates. (1) During Early Jurassic to Early Cretaceous, the North American Plate moved 1900 km westward and 900 km northward relative to the South American Plate. A broad zone including the Caribbean region, i.e., the zone between the North and South America Plates, was a site of left-lateral shear and north-south extension. (2) During Early Cretaceous to Late Cretaceous, the North American Mate moved an additional 1200 km westward relative to South America across this zone. (3) During Late Cretaceous to the end of the Eocene, the North American Plate moved 200 km westward and 400 km northward relative to the South American Plate. (4) From the end of the Eocene to near the end of the Miocene, North America converged on South America some 200 km and moved 100 km eastward relative to it. Through the Mesozoic and earliest Tertiary history of the Caribbean, the region was a shear zone within which left-lateral displacement exceeded 3000 km and north-south extension exceeded 1300 km. In regard to time, 80% of the history of the Caribbean region is one of north-south extension and left-lateral shear. In terms of space, 97% of the shear is left-lateral and the ratio of divergence versus convergence is 7 to 1. Thus, characterizing the Caribbean region, and the Atlantic to its east, as a zone of north-south extension and left-lateral shear, is a fair generalization.

  1. Estimation of primary drainage three-phase relative permeability for organic liquid transport in the vadose zone

    NASA Astrophysics Data System (ADS)

    Oliveira, Leonardo I.; Demond, Avery H.

    2003-11-01

    The modeling of transport of organic liquid contaminants through the vadose zone often requires three-phase relative permeabilities. Since these are difficult to measure, predictive models are usually used. The objective of this study is to assess the ability of eight common models to predict the drainage relative permeability to oil in a three-phase system (water-oil-air). A comparison of the models' estimates using data set from Oak [Oak, M.J., 1990. Three-phase relative permeability of water-wet Berea. In: Seventh Symposium on Enhanced Oil Recovery, Paper SPE/Doe 20183. Tulsa, OK, April 22-25] showed that they provide very different predictions for the same system. The goodness of the models does not increase with the amount of data or computation that the models require. Also, the calculations showed how different interpretations of the models and of the terminology associated with them can significantly impact the predictions. Thus, considerable error may be introduced into the simulations of organic liquid transport in the vadose zone depending on the selection and interpretation of the three-phase relative permeability model.

  2. Gas-Phase Treatment of Technetium in the Vadose Zone at the Hanford Site Central Plateau

    SciTech Connect

    Truex, Michael J.; Szecsody, James E.; Zhong, Lirong; Qafoku, Nikolla

    2014-09-01

    Technetium-99 (Tc-99) is present in the vadose zone of the Hanford Central Plateau and is a concern with respect to the protection of groundwater. The persistence, limited natural attenuation mechanisms, and geochemical behavior of Tc-99 in oxic vadose zone environments must be considered in developing effective alternatives for remediation. This report describes a new in situ geochemical manipulation technique for decreasing Tc-99 mobility using a combination of geochemical Tc-99 reduction with hydrogen sulfide gas and induced sediment mineral dissolution with ammonia vapor, which create conditions for deposition of stable precipitates that decrease the mobility of Tc-99. Laboratory experiments were conducted to examine changes in Tc-99 mobility in vadose zone sediment samples to evaluate the effectiveness of the treatment under a variety of operational and sediment conditions.

  3. Subduction zone tectonic studies to develop concepts for the occurrence of sediment subduction (Phase 2): Volume 2

    SciTech Connect

    Payne, J.; Bandy, B.; Altis, S.; Lee, M.C.; Dwan, S.F.; Ku, K.; Hilde, T.W.C.

    1989-02-01

    The objectives of this study represent a continuation and refinement of the objectives addressed in Phase 1. This study focuses on trying to define the tectonics of sediment subduction at the trench axis through the use of accepted plate tectonic principles and the application of new subduction theory. The fundamental methods include: (1) compilation of all available bathymetric data from our Global Marine Geophysical Data Collection for all major ocean trenches, (2) generation of stacked bathymetric profiles and corresponding navigational maps, and structural maps, (3) selection and analysis of appropriate seismic reflection and refraction profiles and additional supporting data such as side-scan sonar, SEABEAM, magnetic, gravity and drilling data, and (4) detailed study study of selected trench regions in which data quality and/or quantity is exceptional. Phase 2 of this project represents a unique compilation and synthesis of existing data for the world's deep ocean trenches. The analysis of data and discussion of results in the context of current literature aids our understanding of the sediment distribution and nature of sediment deformation through various stages of plate convergence, the determination of whether sediments are subducted or accreted, and the evaluation of the controlling factors for sediment subduction and/or accretion. A discussion on petroleum and natural gas hydrate resource potential is included.

  4. Subduction zone tectonic studies to develop concepts for the occurrence of sediment subduction (Phase 2): Volume 1

    SciTech Connect

    Payne, J.; Bandy, B.; Altis, S.; Lee, M.C.; Dwan, S.F.; Ku, K.; Hilde, T.W.C.

    1989-02-01

    This is volume one of three volumes. The objectives of this study represent a continuation and refinement of the objectives addressed in Phase I. This study focuses on trying to define the tectonics of sediment subduction at the trench axis through the use of accepted plate tectonic principles and the application of new subduction theory. The fundamental methods include: (1) compilation of all available bathymetric data from our Global Marine Geophysical Data Collection for all major ocean trenches, (2) generation of stacked bathymetric profiles and corresponding navigational maps, and structural maps, (3) selection and analysis of appropriate seismic reflection and refraction profiles and additional supporting data such as side-scan sonar, SEABEAM, magnetic, gravity and drilling data, and (4) detailed study of selected trench regions in which data quality and/or quantity is exceptional. Phase II of this project represents a unique compilation and synthesis of existing data for the world's deep ocean trenches. The analysis of data and discussion of results in the context of current literature aids our understanding of the sediment distribution and nature of sediment deformation through various stages of plate convergence, the determination of whether sediments are subducted or accreted, and the evaluation of the controlling factors for sediment subduction and/or accretion. A discussion is included on forearc petroleum and natural gas hydrate resource potential. 128 figs.

  5. Subduction zone tectonic studies to develop concepts for the occurrence of sediment subduction (Phase 2): Volume 3

    SciTech Connect

    Payne, J.; Bandy, B.; Altis, S.; Lee, M.C.; Dwan, S.F.; Ku, K.; Hilde, T.W.C.

    1989-02-01

    The objectives of this study represent a continuation and refinement of the objectives addressed in Phase 1. This study focuses on trying to define the tectonics of sediment subduction at the trench axis through the use of accepted plate tectonic principles and the application of new subduction theory. The fundamental methods include: (1) compilation of all available bathymetric data from our Global Marine Geophysical Data Collection for all major ocean trenches, (2) generation of stacked bathymetric profiles and corresponding navigational maps, and structural maps, (3) selection and analysis of appropriate seismic reflection and refraction profiles and additional supporting data such as side-scan sonar, SEABEAM, magnetic, gravity and drilling data, and (4) detailed study of selected trench regions in which data quality and/or quantity is exceptional. Phase 2 of this project represents a unique compilation and synthesis of existing data for the world's deep ocean trenches. The analysis of data and discussion of results in the context of current literature aids our understanding of the sediment distribution and nature of sediment deformation through various stages of plate convergence, the determination of whether sediments are subducted or accreted, and the evaluation of the controlling factors for sediment subduction and/or accretion. A major emphasis in our analysis of the data was to try and map the seaward-of-the-trench distribution of faults and associated surface roughness. Illustrations and an extensive bibliography are included in the report.

  6. Measurement of optical absorption in polycrystalline CVD diamond plates by the phase photothermal method at a wavelength of 10.6 {mu}m

    SciTech Connect

    Luk'yanov, A Yu; Serdtsev, E V; Volkov, P V; Ral'chenko, Viktor G; Savel'ev, A V; Konov, Vitalii I; Khomich, A V

    2008-12-31

    A highly-efficient phase photothermal method is developed for quantitative measurements of the small optical absorption coefficient in thin plates made of highly transparent materials in which bulk losses significantly exceed surface losses. The bulk absorption coefficient at 10.6 {mu}m is estimated in polycrystalline diamond plates grown from the vapour phase (a CVD diamond). The results are compared with those for natural and synthetic diamond single crystals and with the concentrations of nitrogen and hydrogen impurities. The absorption coefficient of the best samples of the CVD diamond did not exceed 0.06 cm{sup -1}, which, taking into account the high thermal conductivity of the CVD diamond (1800-2200 W mK{sup -1} at room temperature), makes this material attractive for fabricating output windows of high-power CO{sub 2} lasers, especially for manufacturing large-size optics. (laser applications and other topics in quantum electronics)

  7. About the Transformation Phase Zones of Shape Memory Alloys' Fracture Tests on Single Edge-Cracked Specimen

    NASA Astrophysics Data System (ADS)

    Taillebot, V.; Lexcellent, C.; Vacher, P.

    2012-03-01

    The thermomechanical behavior of shape memory alloys is now well mastered. However, a hindrance to their sustainable use is the lack of knowledge of their fracture behavior. With the aim of filling this partial gap, fracture tests on edge-cracked specimens in NiTi have been made. Particular attention was paid to determine the phase transformation zones in the vicinity of the crack tip. In one hand, experimental kinematic fields are observed using digital image correlation showing strain localization around the crack tip. In the other hand, an analytical prediction, based on a modified equivalent stress criterion and taking into account the asymmetric behavior of shape memory alloys in tension-compression, provides shape and size of transformation outset zones. Experimental results are relatively in agreement with our analytical modeling.

  8. CO2 phase mutation by fluctuating water table in the vadose zone over a CCS site

    NASA Astrophysics Data System (ADS)

    Joun, W.; Ha, S. W.; Kim, H. H.; Kim, T. W.; Lee, S. S.; Lee, K. K.

    2015-12-01

    Geological sequestration of carbon dioxide (CO2) is one of the feasible plans to control greenhouse gas emissions. In order to be more perfect, the plan has to prove that the injected CO2 gas will not be leaking. Even if CO2 leaking happens, we should possess a technique which provides information on specific aquifer system before critical effect to ground and subsurface environments. Many parameters have been utilized for early detection before risk to environments by sensing CO2 gas concentration, electric conductivity, pH, and ion analysis. However, these are not enough to all CCS sites for leakage detection. For example, the importance of gas leaking path is emphasized because finding the dominant gas flow path can reduce risk and provide a quick estimation. Herein, we investigate dissolved solute degassing and vertical flow from saturated zone to unsaturated zone in shallow depth aquifer. Especially we focused on the water table fluctuation effect. Based on field data and basic parameters, we perform a pilot scale gas injection test and calculate gas flow saturation with STOMP simulator. The CO2 gas concentrations at different depth levels according to amount of injected CO2 infused water, CO2 gas saturation in vadose zone have different concentration values. If we estimate this phenomenon in vadose zone by using CO2 gas detection method, we could presume that the CO2 dissolved in shallow groundwater is degassing and flow upward into vadose zone. However, the concentration level and change patterns are not same and will be changed according to the pattern of water table fluctuation. This study could be usefully applied to strategic CCS environmental monitoring of CO2 leakage.Acknowledgement: Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003).

  9. Localised Plate Motion on Venus

    NASA Astrophysics Data System (ADS)

    Ghail, R. C.

    1996-03-01

    The volcanic and tectonic features observed in Dali Vinculum, Parga Vinculum and Imdr Regio are concentrated at long, narrow, curvilinear zones, with relatively minor volcanism and tectonism between these zones. These zones, whilst more diffuse than terrestrial plate boundaries, nevertheless define the margins of tectonic plates. In contrast to Earth, however, it appears that venusian plates are neither created nor destroyed by lateral motion. Rather, plates are thinned and intruded at vincula plate boundaries, vertically accreted by small-scale intra-plate (planitia) volcanism and perhaps destroyed by delamination of thickened crust in tesserae and montane regions such as Thetis Regio and Ishtar Terra. The diversity in age both between and within these three areas together with the evidence for infrequent, small scale resurfacing in the planitiae are difficult to reconcile with a non-uniformitarian geological process.

  10. [Characteristics of water-gas two-phase CO2 transport in unsaturated zone].

    PubMed

    Yu, Yanxin; Chen, Jiajun; Wang, Jinsheng; Yun, Ying; Li, Shushen; Wang, Zhiming

    2003-07-01

    The migration of CO2 in soil was simulated through use of soil column, especially the transformation of CO2 between water and gas phases at wetting front was studied. The soil column in the test was 1 m long and the concentration of CO2 solution was 748 mg/L. Through analysis, it was shown that CO2 migration in water phase was governed by advection, dispersion, reaction and mass transfer between water and gas phases, that in gas phase by advection, dispersion, mass transfer between two phases. Sampling method under dynamic condition of two phase flow in soil column was approached and mass transfer coefficient from water phase to gas phase was determined as 0.00061. This showed that there was certain mass transformation of CO2 from water phase to gas phase and yet it was not so significant. This study can provide the quantitative scientific bases for safety assessment of geological disposal of low and intermediate level radioactive waste and environmental impact assessment of solid waste disposal by landfilling. PMID:14551970

  11. Trapping control of phase development in zone melting of Bi-Sr-Ca-Cu-O superconducting fibres

    NASA Astrophysics Data System (ADS)

    Costa, F. M.; Carrasco, M. F.; Silva, R. F.; Vieira, J. M.

    2003-03-01

    Highly-texturized polycrystalline fibres of the Bi-Sr-Ca-Cu-O system have been grown by the laser floating zone technique at seven different pulling rates: (1.1, 2.2, 4.17, 8.3, 16.7, 33.3, 60.5) × 10-6 m s-1. The assessment of the cation segregation at the solid/liquid interface allowed us to calculate their equilibrium and effective distribution coefficients. The equilibrium distribution coefficients (k0,Bi = 0.55, k0,Sr = 0.97, k0,Ca = 1.67, k0,Cu = 1.10) were estimated using the Burton, Primm and Slichter (BPS) theory by taking into account the determined effective values. The effective distribution coefficients tend to unity as long as the pulling rate increases. The composition profiles along the initial transient region of the solidified fibres show a fast approach to the nominal composition as the pulling rate increases. The outstanding effect of the growth speed on superconducting phase type development is explained based on the solute trapping phenomena. The sequence of crystallization for superconducting phases ('2212' rightarrow '4413' rightarrow '2201') with pulling rate is a spontaneous effect of the system thermodynamics in order to balance the Bi trapping. This phase sequence corresponds to the smallest change of Bi chemical potential from the liquid phase to the solid phase. A diagram of free energy curves of the interdendritic superconducting phases illustrates the partitionless solidification phenomena at the highest growth speed.

  12. Microseismicity and b-values of the Wabash Valley Intraplate Seismic Zone from short-period phased arrays

    NASA Astrophysics Data System (ADS)

    Conder, J. A.; Milliron, K.; Zhu, L.

    2014-12-01

    Two phased arrays of 9 short-period stations each are currently recording in the Wabash Valley Seismic Zone (WVSZ) as part of the EarthScope Wabash FlexArray project. The phased arrays aim to address the level of microseismicity produced by the intraplate seismic zone. Although seismic hazard maps of the U.S. Midwest are dominated by the New Madrid Seismic Zone (NMSZ), the WVSZ has released 40% more seismic energy than the NMSZ over the last half century with four events larger than M5 and only one in the NMSZ reaching that threshold. A comparison of event frequency statistics suggests two markedly different systems. The NMSZ exhibits b-values near unity, but the WVSZ exhibits much smaller b-values in the 0.6-0.7 range. Deviations less than unity may be controlled through crack geometry and/or greater shear stresses possibly indicating a time-dependent, or migrating, behavior in mid-continent. Alternatively, it may be the case that the low b-values are simply a reflection of less complete catalog than the NMSZ. A previous short-term microseismicity study of the WVSZ shows a dearth of non-anthropogenic sources in the Wabash. The phased array near the central portion of the WVSZ largely confirms the previously noted lack of substantial natural seismicity along the central portion of the fault system and the associated low b-values. However, the phased array near the southern termination of the fault system shows significantly more activity. Importantly, the largest events from the Wabash, including the 2008 M5.4 Mt. Carmel and the 1968 M5.5 Harrisburg events occurred near the northern and southern ends of the fault system. The phased arrays seem to indicate different portions of the fault system yielding different levels of activity. As the catalogs become more complete, there is a preliminary suggestion that the anomalously low b-values for the Wabash do not denote a system under significantly larger stresses, but rather a conflation of regions along-strike of the

  13. Elasticity and thermodynamics of the 3.65 Å phase in subduction zone settings

    NASA Astrophysics Data System (ADS)

    Mookherjee, M.; Speziale, S.; Marquardt, H.; Jahn, S.; Wunder, B.; Koch-Müller, M.; Liermann, H.

    2013-12-01

    How efficiently water is transported into the deeper realms of the Earth is related to the stability of hydrous phases. And to evaluate whether these hydrous phases are indeed stabilized in the hydrated lithosphere, it is important to constrain the elasticity of the hydrous phases and relate them with the geophysical observations. Based on experimental phase stability studies, 3.65 Å phase [MgSi(OH)6] (Wunder et al., 2011) is an important candidate phase for transporting water into the deep interior of the Earth. In this study, we present the equation of state, full elastic constant tensor, and its pressure dependence. In addition, we also evaluate the fundamental thermodynamic quantities and speculate on the factors that are likely to affect and enhance the thermal stability of the 3.65 Å phase and thus its efficiency in transporting water. We use a combination of synchrotron x-ray diffraction and ab initio simulations to constrain the equation of state and elasticity of the 3.65 Å phase. We find that the pressure-volume results for the 3.65 Å phase are well represented by a third order Birch-Murnaghan finite strain formulation, with K0 = 84 GPa, K' = 5.0 and V0 = 194.5 Å3. The bulk sound velocities of the 3.65 Å phase are significantly faster compared to the layered hydrous phases stable at lower pressure conditions and may not be distinguishable from the major mantle phases such as high-pressure clino-enstatite phase. The full elastic constant tensor reveals significant anisotropy with AVP = 10 %, AVS1 = 23 %, and AVS2 = 20 % at pressures corresponding to the lower part of the upper mantle. Reference Wunder, B., Wirth, R., Koch-Müller, M., 2011. The 3.65 Å phase in the system MgO-SiO2-H2O: Synthesis, composition, and structure. American Mineralogist, 96, 1207-1214. Acknowledgements MM is supported by US NSF grant # EAR 1250477 and also acknowledges computing resources (EAR130015) from XSEDE (OCI-1053575).

  14. Analysis of heat-affected zone phase transformations using in situ spatially resolved x-ray diffraction with synchrotron radiation

    SciTech Connect

    Elmer, J.W.; Wong, J.; Froeba, M.; Waide, P.A.; Larson, E.M.

    1996-03-01

    Spatially resolved X-ray diffraction (SRXRD) consists of producing a submillimeter size X-ray beam from an intense synchrotron radiation source to perform real-time diffraction measurements on solid materials. This technique was used int his study to investigate the crystal phases surrounding a liquid weld pool in commercial purity titanium and to determine the location of the phase boundary separating the high-temperature body-centered-cubic (bcc) {beta} phase from the low-temperature hexagonal-close-packed (hcp) {alpha} phase. The experiments were carried out at the Stanford Synchrotron Radiation Laboratory (SSRL) using a 0.25 x 0.50 mm X-ray probe that could be positioned with 10-{micro}m precision on the surface of a quasistationary gas tungsten arc weld (GTAW). The SRXRD results showed characteristic hcp, bcc, and liquid diffraction patterns at various points along the sample, starting from the base metal through the heat-affected zone (HAZ) and into the weld pool, respectively. Analyses of the SRXRD data show the coexistence of bcc and hcp phases in the partially transformed (outer) region of the HAZ and single-phase bcc in the fully transformed (inner) region of the HAZ. Postweld metallographic examinations of the HAZ, combined with a conduction-based thermal model of the weld, were correlated with the SRXRD results. Finally, analysis of the diffraction intensities of the hcp and bcc phases was performed on the SRXRD data to provide additional information about the microstructural conditions that may exist in the HAZ at temperature during welding. This work represents the first direct in situ mapping of phase boundaries in fusion welds.

  15. Pancharatnam-Berry phase optical elements for generation and control of complex light: generalized superelliptical q-plates

    NASA Astrophysics Data System (ADS)

    Piccirillo, Bruno; Kumar, Vijay; Marrucci, Lorenzo; Santamato, E.

    2015-03-01

    We present newly conceived liquid-crystal-based retardation waveplates in which the optic axis distribution has a "superelliptically" symmetric azimuthal structure with a topological charge q superimposed. Such devices, named superelliptical q-plates, act as polarization-to-spatial modes converters that can be used to produce optical beams having peculiar spiral spectra. These spectra reflect the topological charge of the optic axis distribution as well as the symmetry properties of the underlying superellipse. The peculiar capability of q-plates of producing optical modes entangled with respect to spin and orbital angular momentum is here extended to superelliptical q-plates in order to create more complex optical modes structurally inseparable with respect to polarization and spatial degrees of freedom. Such superelliptical modes can play a crucial role in studying polarization singularities or to develop polarization metrology.

  16. Using Vapor Phase Tomography to Measure the Spatial Distribution of Vapor Concentrations and Flux for Vadose-zone VOC Sources

    PubMed Central

    Mainhagu, J.; Morrison, C.; Brusseau, M.L.

    2015-01-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were combined with the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site. PMID:25835545

  17. Using Vapor Phase Tomography to Measure the Spatial Distribution of Vapor Concentrations and Flux for Vadose-Zone VOC Sources

    NASA Astrophysics Data System (ADS)

    Mainhagu, J.; Brusseau, M. L. L.; Morrison, C. N.

    2015-12-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site.

  18. Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources

    NASA Astrophysics Data System (ADS)

    Mainhagu, J.; Morrison, C.; Brusseau, M. L.

    2015-06-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site.

  19. Geodetic constraints on active tectonics of the Western Mediterranean: Implications for the kinematics and dynamics of the Nubia-Eurasia plate boundary zone

    NASA Astrophysics Data System (ADS)

    Vernant, Philippe; Fadil, Abdelali; Mourabit, Taoufik; Ouazar, Driss; Koulali, Achraf; Davila, Jose Martin; Garate, Jorge; McClusky, Simon; Reilinger, Robert

    2010-04-01

    We present GPS observations in Morocco and adjacent areas of Spain from 15 continuous (CGPS) and 31 survey-mode (SGPS) sites extending from the stable part of the Nubian plate to central Spain. We determine a robust velocity field for the W Mediterranean that we use to constrain models for the Iberia-Nubia plate boundary. South of the High Atlas Mountain system, GPS motions are consistent with Nubia plate motions from prior geodetic studies. We constrain shortening in the Atlas system to <1.5 mm/yr, 95% confidence level. North of the Atlas Mountains, the GPS velocities indicate Nubia motion with respect to Eurasia, but also a component of motion normal to the direction of Nubia-Eurasia motion, consisting of southward translation of the Rif Mountains in N Morocco at rates exceeding 5 mm/yr. This southward motion appears to be directly related to Miocene opening of the Alboran Sea. The Betic Mountain system north of the Alboran Sea is characterized by WNW motion with respect to Eurasia at ˜1-2 mm/yr, paralleling Nubia-Eurasia relative motion. In addition, sites located in the Betics north of the southerly moving Rif Mountains also indicate a component of southerly motion with respect to Eurasia. We interpret this as indicating that deformation associated with Nubia-Eurasia plate motion extends into the southern Betics, but also that the Betic system may be affected by the same processes that are causing southward motion of the Rif Mountains south of the Alboran Sea. Kinematic modeling indicates that plate boundary geometries that include a boundary through the Straits of Gibraltar are most compatible with the component of motion in the direction of relative plate motion, but that two additional blocks (Alboran-Rif block, Betic Mountain block), independent of both Nubia and Eurasia are needed to account for the motions of the Rif and Betic Mountains normal to the direction of relative plate motion. We speculate that the southward motions of the Alboran-Rif and Betic

  20. Immobilization of Radionuclides in the Hanford Vadose Zone by Incorporation in Solid Phases

    SciTech Connect

    Gordon E. Brown, Jr.; Jeffrey G. Catalano; Jeffrey A. Warner; Samual Shaw; Daniel Grolimund

    2005-01-24

    The Department of Energy's Hanford Nuclear Site located in Washington State has accumulated over 2 million curies of radioactive waste from activities related to the production of plutonium (Ahearne, 1997). Sixty-seven of the single-shelled tanks located at the site are thought to have leaked, allowing between 2 and 4 million liters of waste fluids into the underlying vadose zone. The chemical processes employed at the Hanford Site to extract plutonium, as well as the need to minimize corrosion of the high-carbon steel storage tanks, resulted in uncharacterized hyperalkaline waste streams rich in radionuclides as well as other species including significant amounts of sodium and aluminum.

  1. Time variation in the reaction-zone structure of two-phase spray detonations.

    NASA Technical Reports Server (NTRS)

    Pierce, T. H.; Nicholls, J. A.

    1973-01-01

    A detailed theoretical analysis of the time-varying detonation structure in a monodisperse spray is presented. The theory identifies experimentally observed reaction-zone overpressures as deriving from blast waves formed therein by the explosive ignition of the spray droplets, and follows in time the motion, change in strength, and interactions of these blast waves with one another, and with the leading shock. The results are compared with experimental data by modeling the motion of a finite-size circular pressure transducer through the theoretical data field in an x-t space.

  2. Grain size reduction of feldspar and pyroxene, phase mixing, and strain localization in lower crustal shear zones (Lofoten, Norway)

    NASA Astrophysics Data System (ADS)

    Menegon, L.; Stunitz, H.; Nasipuri, P.; Svahnberg, H.; Heilbronner, R.

    2011-12-01

    High temperature shear zones are common in the magmatic suite of the granulite facies Lofoten basement of Norway, and typically consist of narrow structures (1 cm to 1 m in thickness) showing a mylonite-to ultramylonite transition from the shear zone boundary to the shear zone center. In this contribution we examine the deformation microstructures and synkinematic mineral assemblages of shear zones developed from a mangerite (=monzonite) protolith. The mineral assemblage in the host mangerite indicates anhydrous conditions (mesoperthite + clinopyroxene ± orthopyroxene), whereas the mineral assemblage in the shear zones consists of plagioclase + K-feldspar + quartz + hornblende + calcite + biotite ± clinopyroxene and indicates hydrated conditions. Hornblende-plagioclase geothermobarometry yields upper amphibolite- to granulite facies conditions during shearing (730-760° C, 0.55-0.8 GPa). The mylonite consists of two distinct compositional domains: a pyroxene-derived aggregate and a feldspar-derived aggregate. The pyroxene-derived aggregate consists of the products of the following breakdown reaction: clinopyroxene + plagioclase ± K-feldspar ± orthopyroxene + H2O + CO2 --> quartz + hornblende + calcite ± biotite. In the feldspar-derived aggregate fractured fragments of mesoperthite are surrounded by a bi-phase mixture of recrystallized plagioclase and K-feldspar. EBSD analysis indicates that the recrystallized grains originated as micro-fragments from fracturation, and recrystallization was compositionally-induced (e.g. An22 average composition of plagioclase in the mesoperthite, An14 in the recrystallized aggregate). Detailed grain size, grain shape and EBSD analysis indicate that diffusion creep was the dominant deformation mechanism in both aggregates. Spatial distribution of K-feldspar and plagioclase shows a well dispersed aggregate and may serve as a tool to characterize diffusion creep deformation in phase mixtures. In the ultramylonite the two

  3. Significance of groundwater flux on contaminant concentration and mass discharge in the nonaqueous phase liquid (NAPL) contaminated zone

    NASA Astrophysics Data System (ADS)

    Zhu, Jianting; Sun, Dongmin

    2016-09-01

    Groundwater flowing through residual nonaqueous phase liquid (NAPL) source zone will cause NAPL dissolution and generate large contaminant plume. The use of contaminant mass discharge (CMD) measurements in addition to NAPL aqueous phase concentration to characterize site conditions and assess remediation performance is becoming popular. In this study, we developed new and generic numerical models to investigate the significance of groundwater flux temporal variations on the NAPL source dynamics. The developed models can accommodate any temporal variations of groundwater flux in the source zone. We examined the various features of groundwater flux using a few selected functional forms of linear increase/decrease, gradual smooth increase/decrease, and periodic fluctuations with a general trend. Groundwater flux temporal variations have more pronounced effects on the contaminant mass discharge dynamics than the aqueous concentration. If the groundwater flux initially increases, then the reduction in contaminant mass discharge (CMDR) vs. NAPL mass reduction (MR) relationship is mainly downward concave. If the groundwater flux initially decreases, then CMDR vs. MR relationship is mainly upward convex. If the groundwater flux variations are periodic, the CMDR vs. MR relationship tends to also have periodic variations ranging from upward convex to downward concave. Eventually, however, the CMDR vs. MR relationship approaches 1:1 when majority of the NAPL mass becomes depleted.

  4. Significance of groundwater flux on contaminant concentration and mass discharge in the nonaqueous phase liquid (NAPL) contaminated zone.

    PubMed

    Zhu, Jianting; Sun, Dongmin

    2016-09-01

    Groundwater flowing through residual nonaqueous phase liquid (NAPL) source zone will cause NAPL dissolution and generate large contaminant plume. The use of contaminant mass discharge (CMD) measurements in addition to NAPL aqueous phase concentration to characterize site conditions and assess remediation performance is becoming popular. In this study, we developed new and generic numerical models to investigate the significance of groundwater flux temporal variations on the NAPL source dynamics. The developed models can accommodate any temporal variations of groundwater flux in the source zone. We examined the various features of groundwater flux using a few selected functional forms of linear increase/decrease, gradual smooth increase/decrease, and periodic fluctuations with a general trend. Groundwater flux temporal variations have more pronounced effects on the contaminant mass discharge dynamics than the aqueous concentration. If the groundwater flux initially increases, then the reduction in contaminant mass discharge (CMDR) vs. NAPL mass reduction (MR) relationship is mainly downward concave. If the groundwater flux initially decreases, then CMDR vs. MR relationship is mainly upward convex. If the groundwater flux variations are periodic, the CMDR vs. MR relationship tends to also have periodic variations ranging from upward convex to downward concave. Eventually, however, the CMDR vs. MR relationship approaches 1:1 when majority of the NAPL mass becomes depleted. PMID:27500747

  5. Paleomagnetic rotation pattern of the southern Chile fore-arc sliver (38°S-42°S): A new tool to evaluate plate locking along subduction zones

    NASA Astrophysics Data System (ADS)

    Hernandez-Moreno, Catalina; Speranza, Fabio; Di Chiara, Anita

    2016-02-01

    The Chile fore arc at 37°S-47°S represents the coseismic deformation zone of the 1960 Mw 9.5 Valdivia earthquake. Here we report on the paleomagnetism of 43 Oligocene-Pleistocene volcanic sites from the fore-arc sliver between 38°S and 42°S. Sites were gathered west of the 1000 km long Liquiñe-Ofqui dextral fault zone (LOFZ) that represents the eastern fore-arc sliver boundary. Nineteen reliable sites reveal that the fore arc is characterized by counterclockwise (CCW) rotations of variable magnitude, except at 40°S-41°S, where ultrafast (>50°/Myr) clockwise (CW) rotations occur within a 30 km wide zone adjacent to the LOFZ. CCW rotation variability (even at close sites) and rapidity (>10°/Myr) suggest that the observed block rotation pattern is related to NW-SE seismically active sinistral faults crosscutting the whole fore arc. According to previously published data, CW rotations up to 170° also occur east of the LOFZ and have been related to ongoing LOFZ shear. We suggest that the occurrence and width of the eastern fore-arc sliver undergoing CW rotations is a function of plate coupling along the subduction zone interface. Zones of high coupling enhance stress normal to the LOFZ, induce high LOFZ strength, and yield a wide deformation zone characterized by CW rotations. Conversely, low coupling imply a weak LOFZ, a lack of CW rotations, and a fore arc entirely dominated by CCW rotations related to sinistral fault kinematics. Our locking inferences are in good agreement with those recently derived by GPS analysis and indicate that seismotectonic segment coupling has remained virtually unchanged during the last 5 Ma.

  6. Origin of Small Tectonic Plates

    NASA Astrophysics Data System (ADS)

    Mallard, C.; Coltice, N.; Seton, M.; Müller, D.; Tackley, P.

    2015-12-01

    The plate tectonic theory allowed to split the Earth surface into 6 (Le Pichon 1968) to 52 tectonic plates (Bird 2003). These plates are separated into two groups: the first of 7 large plates and the second of numerous smaller plates (Morra et al 2013). Previous studies using the reconstruction of the past 200 My, suggest that the size of large plates is driven by mantle flow. But the tools employed are descriptive (Morra et al 2013, Sornette and Pisarenko 2003), hence ignoring forces and physical principles within the lithosphere and the mantle. The processes at the origin of small plates remain unknown. We developed a new approach to explain the plate sizes. We demonstrate that the physics of convection drives it. We applied plate tectonics theory on 3D spherical convection models generating plate-like motions, which give access to a complete survey of data: velocities, viscosity and heat flow. Our data show that (1) the large plates depend on the dominating scale of the convective flow due to the initiation or the shutdown of subductions; (2) the smaller plates are generated thanks to large variability of regional stresses along subduction zone by slab pull and suction influenced by the geometry of trenches. Our results are consistent with the quick reorganizations of back-arc basins occuring synchronously with the modification of subduction zones geometry around the Pacific plate (Sdrolias et al 2004). Hence, we conclude that (1) the decreasing number of small plates in the plate reconstructions back in time is an artifact induced by their short lifetime, that is why they are artificially ignored; (2) the geometry of past trenches is simplified leading to an underestimation of the length of subduction zones.

  7. Phase-Amplitude Coupling Is Elevated in Deep Sleep and in the Onset Zone of Focal Epileptic Seizures

    PubMed Central

    Amiri, Mina; Frauscher, Birgit; Gotman, Jean

    2016-01-01

    The interactions between different EEG frequency bands have been widely investigated in normal and pathologic brain activity. Phase-amplitude coupling (PAC) is one of the important forms of this interaction where the amplitude of higher frequency oscillations is modulated by the phase of lower frequency activity. Here, we studied the dynamic variations of PAC of high (gamma and ripple) and low (delta, theta, alpha, and beta) frequency bands in patients with focal epilepsy in different sleep stages during the interictal period, in an attempt to see if coupling is different in more or less epileptogenic regions. Sharp activities were excluded to avoid their effect on the PAC. The results revealed that the coupling intensity was generally the highest in stage N3 of sleep and the lowest in rapid eye movement sleep. We also compared the coupling strength in different regions [seizure onset zone (SOZ), exclusively irritative zone, and normal zone]. PAC between high and low frequency rhythms was found to be significantly stronger in the SOZ compared to normal regions. Also, the coupling was generally more elevated in spiking channels outside the SOZ than in normal regions. We also examined how the power in the delta band correlates to the PAC, and found a mild but statistically significant correlation between slower background activity in epileptic channels and the elevated coupling in these channels. The results suggest that an elevated PAC may reflect some fundamental abnormality, even after exclusion of sharp activities and even in the interictal period. PAC may therefore contribute to understanding the underlying dynamics of epileptogenic brain regions. PMID:27536227

  8. Phase-Amplitude Coupling Is Elevated in Deep Sleep and in the Onset Zone of Focal Epileptic Seizures.

    PubMed

    Amiri, Mina; Frauscher, Birgit; Gotman, Jean

    2016-01-01

    The interactions between different EEG frequency bands have been widely investigated in normal and pathologic brain activity. Phase-amplitude coupling (PAC) is one of the important forms of this interaction where the amplitude of higher frequency oscillations is modulated by the phase of lower frequency activity. Here, we studied the dynamic variations of PAC of high (gamma and ripple) and low (delta, theta, alpha, and beta) frequency bands in patients with focal epilepsy in different sleep stages during the interictal period, in an attempt to see if coupling is different in more or less epileptogenic regions. Sharp activities were excluded to avoid their effect on the PAC. The results revealed that the coupling intensity was generally the highest in stage N3 of sleep and the lowest in rapid eye movement sleep. We also compared the coupling strength in different regions [seizure onset zone (SOZ), exclusively irritative zone, and normal zone]. PAC between high and low frequency rhythms was found to be significantly stronger in the SOZ compared to normal regions. Also, the coupling was generally more elevated in spiking channels outside the SOZ than in normal regions. We also examined how the power in the delta band correlates to the PAC, and found a mild but statistically significant correlation between slower background activity in epileptic channels and the elevated coupling in these channels. The results suggest that an elevated PAC may reflect some fundamental abnormality, even after exclusion of sharp activities and even in the interictal period. PAC may therefore contribute to understanding the underlying dynamics of epileptogenic brain regions. PMID:27536227

  9. Crustal structure and evolution of the southern Juan de Fuca plate from wide-angle seismic data: Insights into the hydration state of the incoming plate off Cascadia subduction zone

    NASA Astrophysics Data System (ADS)

    Horning, G.; Canales, J. P.; Carbotte, S. M.; Nedimovic, M. R.; Carton, H. D.

    2014-12-01

    A multi-channel seismic reflection and wide-angle refraction seismic experiment was conducted on the Juan de Fuca (JdF) plate to investigate the evolution of the plate from accretion to its subduction at the Cascadia margin. Hydration of the upper crust (UC) of the JdF Plate is well documented, but the state of hydration of the lower crust (LC) and upper mantle (UM] remains to be investigated. A 2D P-wave velocity model of the plate is derived from a joint reflection-refraction travel-time inversion of wide-angle seismic data. Stacked MCS reflection images together with modeled sedimentary velocities define an increasing thickness of sedimentary cover of up to 2.7km. Evidence for bending-related faulting is identified in coincident MCS images both indirectly as faulting in the sedimentary layer [Gibson, et al., this meeting] and directly as dipping crustal reflectors [Han et al., this meeting]. Three first order features are evident in the patterns of crustal velocity variations along the profile. 1: Crustal velocities at 150-250 km landward of the spreading ridge (~5 Ma age) show reduced velocities up to -0.20 km/s in comparison to velocities in younger crust (~3 Ma) 100-150 km from the ridge. This decrease in velocities is coincident with a propagator wake. 2: Upper crustal velocities begin to increase at 170km from the deformation front (DF), which coincides with the first evidence of faulting from sedimentary offsets. Crustal velocities start a decreasing trend at 80km from the DF where fault throws are seen to begin increasing trend landward. 3: UC velocities in the region of directly imaged crustal faulting (40km from trench) increase ~0.5km/s at the DF, while LC velocities decrease ~0.3km/s. The contrasting behavior in the upper and lower crust may indicate that bending promotes hydrothermal circulation in the outer rise. Circulation may be vigorous enough within the sediments/UC so that any residual shallow porosity is clogged with alteration products

  10. Formation of III–V ternary solid solutions on GaAs and GaSb plates via solid-phase substitution reactions

    SciTech Connect

    Vasil’ev, V. I.; Gagis, G. S. Kuchinskii, V. I.; Danil’chenko, V. G.

    2015-07-15

    Processes are considered in which ultrathin layers of III–V ternary solid solutions are formed via the delivery of Group-V element vapors to GaAs and GaSb semiconductor plates, with solid-phase substitution reactions occurring in the surface layers of these plates. This method can form defect-free GaAs{sup 1–x}P{sup x}, GaAs{sup x}Sb{sup 1–x}, and GaP{sup x}Sb{sup 1–x} layers with thicknesses of 10–20 nm and a content x of the embedded components of up to 0.04.

  11. In-situ Phase transformation study in fine grained heat affected zone of Grade 91 steels

    SciTech Connect

    Babu, Sudarsanam Suresh; Yamamoto, Yukinori; Santella, Michael L; Yu, Xinghua; Komizo, Prof. Y; Terasaki, Prof. H

    2014-01-01

    Creep strength-enhanced ferritic (CSEF) steels such as the 9 Cr steel [ASTM A387 Grade 91] are widely used as tubing and piping in the new generation of fossil fired power plants. Microstructures in the fine-grained heat affected zone (FGHAZ) may significantly reduce creep strength leading Type IV failures. Current research suggest that reducing pre-weld tempering temperature from 760 C (HTT) to 650 C (LTT) has the potential to double the creep life of these welds. To understand this improvement, time-resolved X-ray diffraction (TRXRD) measurement with synchrotron radiation was used to characterize the microstructure evolution during fine grained heat-affected zone (HAZ) thermal cycling of grade 91 steel. The measurements showed both M23C6 (M=Fe, Cr) and MX (M=Nb, V; X=C,N) are present in the sample after the HTT condition. Near equilibrium fraction of M23C6 was measured in high temperature tempering condition (HTT, 760 C). However, the amount of M23C6 in LTT condition was very low since the diffraction peaks are close to the background. During simulated FGHAZ thermal cycling, the M23C6 partially dissolved in HTT sample. Interestingly, MX did not dissolve in both LTT and HTT samples. Hypothesis for correlation of M23C6 carbide distribution and pre-mature creep failure in FGHAZ will be made.

  12. Plate motion

    SciTech Connect

    Gordon, R.G. )

    1991-01-01

    The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.

  13. Phase 2 development of Great Lakes algorithms for Nimbus-7 coastal zone color scanner

    NASA Technical Reports Server (NTRS)

    Tanis, Fred J.

    1984-01-01

    A series of experiments have been conducted in the Great Lakes designed to evaluate the application of the NIMBUS-7 Coastal Zone Color Scanner (CZCS). Atmospheric and water optical models were used to relate surface and subsurface measurements to satellite measured radiances. Absorption and scattering measurements were reduced to obtain a preliminary optical model for the Great Lakes. Algorithms were developed for geometric correction, correction for Rayleigh and aerosol path radiance, and prediction of chlorophyll-a pigment and suspended mineral concentrations. The atmospheric algorithm developed compared favorably with existing algorithms and was the only algorithm found to adequately predict the radiance variations in the 670 nm band. The atmospheric correction algorithm developed was designed to extract needed algorithm parameters from the CZCS radiance values. The Gordon/NOAA ocean algorithms could not be demonstrated to work for Great Lakes waters. Predicted values of chlorophyll-a concentration compared favorably with expected and measured data for several areas of the Great Lakes.

  14. Application of a Persistent Dissolved-phase Reactive Treatment Zone for Mitigation of Mass Discharge from Sources Located in Lower-Permeability Sediments

    PubMed Central

    Marble, J.C.; Brusseau, M.L.; Carroll, K.C.; Plaschke, M.; Fuhrig, L.; Brinker, F.

    2015-01-01

    The purpose of this study is to examine the development and effectiveness of a persistent dissolved-phase treatment zone, created by injecting potassium permanganate solution, for mitigating discharge of contaminant from a source zone located in a relatively deep, low-permeability formation. A localized 1,1-dichloroethene (DCE) source zone comprising dissolved- and sorbed-phase mass is present in lower permeability strata adjacent to a sand/gravel unit in a section of the Tucson International Airport Area (TIAA) Superfund Site. The results of bench-scale studies conducted using core material collected from boreholes drilled at the site indicated that natural oxidant demand was low, which would promote permanganate persistence. The reactive zone was created by injecting a permanganate solution into multiple wells screened across the interface between the lower-permeability and higher-permeability units. The site has been monitored for nine years to characterize the spatial distribution of DCE and permanganate. Permanganate continues to persist at the site, and a substantial and sustained decrease in DCE concentrations in groundwater has occurred after the permanganate injection.. These results demonstrate successful creation of a long-term, dissolved-phase reactive-treatment zone that reduced mass discharge from the source. This project illustrates the application of in-situ chemical oxidation as a persistent dissolved-phase reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass discharge into groundwater. PMID:26300570

  15. Plate tectonics, damage and inheritance.

    PubMed

    Bercovici, David; Ricard, Yanick

    2014-04-24

    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. PMID:24717430

  16. Novel solid-phase refolding method for preparation of scFv-immobilized polystyrene plates with high-antigen-binding activity.

    PubMed

    Kumada, Yoichi; Shiritani, Yuki; Hamasaki, Kyoko; Nakagawa, Aya; Sasaki, Eiju; Kishimoto, Michimasa

    2010-10-01

    In the present study, we demonstrated site-specific immobilization and solid-phase refolding of single-chain Fv antibodies on hydrophilic polystyrene (phi-PS) plates that was mediated by novel polystyrene binding peptides (PS-tags: RIIIRRIRR), which were originally isolated and optimized in previous studies. Three PS-tag-fused scFvs, namely scFv-PS, scFv-(PS), and scFv-PSII, which were over-expressed in the insoluble fraction of Escherichia coli cells were denatured and site-specifically immobilized onto hydrophilic PS plates in the presence of 0.5-4 M urea and 0.1% Tween 20. The antigen-binding activity of the scFvs was efficiently recovered by washing the surface of the plate with PBS that contained 0.1% Tween 20 (PBST). The solid-phase refolding mediated by PS-tag was successfully applied to several scFvs such as mouse anti-CRP antibodies and an anti-RNase antibody, although further investigation of the versatility of scFv-PSII is needed. The maximal density of PS-tag-fused scFvs was increased more than 15-fold compared with a whole monoclonal antibody (mAb) immobilized on Maxisorp and, consequently, the sensitivity of PS-tag-fused scFvs for CRP in a sandwich ELISA was increased 25-fold. Thus, the novel, solid-phase, refolding method mediated by a PS-tag will be very useful for preparation of solid supports coated with recombinant antibody fragments, which can be used in immunoassays and immuno-separation. PMID:20661728

  17. Fabrication of Alternating-Phase Fed Single-Layer Slotted Waveguide Arrays Using Plastic Materials with Metal-Plating

    NASA Astrophysics Data System (ADS)

    Zhang, Miao; Hirokawa, Jiro; Ando, Makoto

    Lightweight single-layer slotted waveguide array antennas are fabricated using plastic materials with metal-plating. A plastic material that has good heat-radiation properties is investigated. Three types of antennas are fabricated by milling, using ABS resin, heat-radiating plastic, and aluminum alloy. In measurements, all three types of antennas are confirmed to have almost the same VSWR and gain in the 25GHz frequency band.

  18. Microscopic Morphology and Microstructure of Ti-N and Ti-Ni Phase Between the Dilution Zone and the Clad Zone in Laser Remelting NiCrBSi/TiN Layer on Ti-6Al-4V Alloy Surface

    NASA Astrophysics Data System (ADS)

    Liu, Rongxiang; Guo, Lixin; Lei, Tingquan

    The microscopic morphology and microstructure of Ti-N and Ti-Ni phase between the dilution zone and the clad zone in laser remelting NiCrBSi/TiN layer on a Ti-6Al-4V alloy were characterized using TEM and SEM. The experimental results showed that during laser irradiation heating, TiN particles were partially dissolved into the melted Ni-base alloy, and the dissolved Ti and N atoms were precipitated in the form of TiN, TiN0.3. Ti exhibits height activity, it combines with Ni forming Ti2Ni, TiNi matrix intermetallic during laser remelting, faults exist in the Ti2Ni and TiNi phase, and crystal lattice of TiNi phase is superlattice. Lastly, the cause of the formation of the Ti-N and Ti-Ni phase is discussed.

  19. Vapor-phase interactions and diffusion of organic solvents in the unsaturated zone

    USGS Publications Warehouse

    Roy, W.R.; Griffin, R.A.

    1990-01-01

    This article presents an analysis of the interactions and static movement of 37 organic solvents as vapors through the unsaturated soil zone. The physicochemical interactions of the organic vapors with unsaturated soil materials were emphasized with focus on diffusive, and adsorptive interactions. Fick's Law and porous media diffusion coefficients for most of the solvent vapors were either compiled or estimated; coefficients were not available for some of the fluorinated solvents. The adsorption of some of the solvent vapors by silica was concluded to be due to hydrogen bond formation with surface silanol groups. Heats of adsorption data for different adsorbents were also compiled. There were very few data on the adsorption of these solvent vapors by soils, but it appears that the magnitude of adsorption of nonpolar solvents is reduced as the relative humidity of the vapor-solid system is increased. Consequently, the interaction of the vapors may then separated into two processes; (1) gas-water partitioning described by Henry's Law constants, and (2) solid-water adsorption coefficients which may be estimated from liquid-solid partition coefficients (Kd values). ?? 1990 Springer-Verlag New York Inc.

  20. Mitigation of atmospheric phase delays in InSAR data, with application to the eastern California shear zone

    NASA Astrophysics Data System (ADS)

    Tymofyeyeva, Ekaterina; Fialko, Yuri

    2015-08-01

    We present a method for estimating radar phase delays due to propagation through the troposphere and the ionosphere based on the averaging of redundant interferograms that share a common scene. Estimated atmospheric contributions can then be subtracted from the radar interferograms to improve measurements of surface deformation. Inversions using synthetic data demonstrate that this procedure can considerably reduce scatter in the time series of the line-of-sight displacements. We demonstrate the feasibility of this method by comparing the interferometric synthetic aperture radar (InSAR) time series derived from ERS-1/2 and Envisat data to continuous Global Positioning System data from eastern California. We also present results from several sites in the eastern California shear zone where anomalous deformation has been reported by previous studies, including the Blackwater fault, the Hunter Mountain fault, and the Coso geothermal plant.

  1. New observations of the active deformation along the oblique collision/subduction boundary zone between the North American and Caribbean plates (northern Hispaniola offshore margin)

    NASA Astrophysics Data System (ADS)

    Carbó-Gorosabel, Andrés; Granja Bruña, José Luis; Rodríguez Zurrunero, Álvaro; Gómez de la Peña, Laura; Muñoz-Martín, Alfonso; Gómez Ballesteros, María; Gorosabel Araus, José Miguel; Espinosa, Salvador; Pazos, Anatonio; Catalán, Manuel; Yamil Rodríguez Asilis, Hector; Nuñez, José Luis; Muñoz, Santiago; ten Brink, Uri S.; Quijano, Jesús; Llanes Estrada, Pilar; Martín Dávila, José; Druet, María

    2015-04-01

    The Caribbean plate is moving relative to the North American plate at a rate of 20.0 ± 0.4 mm/y towards 074° ± 1°. This eastward motion has been taking place during most of the Cenozoic developing a 250 km-wide band of deformation, in which microplate and block tectonics take place. The eastward motion of the Hispaniola block is being impeded relative to the motion of the Caribbean plate's interior due to the collision with the Bahamas banks. This collision has resulted in the development of the Northern Hispaniola deformed belt along the northern Hispaniola offshore margin. A series of large (M6.2-M8.1) thrust earthquakes from 1943-1953, and two significant events in 1994 (M5.6) and 2003 (M6.4) occurred close to the city of Puerto Plata have been attributed to oblique collision/subduction of the North America plate and Bahamas banks beneath the northern Hispaniola. 300 km of 2D multi-channel seismic (MCS) reflection data and approximately 15000 km2 of high-resolution, systematic swath bathymetry data were recorded in the northern Hispaniola offshore margin as part of a larger survey carried out in November-December of 2013 aboard the Spanish R/V Sarmiento de Gamboa. MCS profiles were collected shooting a GI gun array (GGUN-II®) of 1750 ci. every 37.5 m and the signal recorded in a 3000 m-long streamer with 240 channels (Sentinel Sercel®). Differential GPS navigated high-resolution bathymetry data were collected using the hull-mounted Hydrosweep ATLAS DS echo-sounder system. Using new high-resolution multibeam bathymetry and MCS data, combined with previous 2D seismic data, we have studied the along- and across-strike variations of the geomorphology and shallower structure of the northern Hispaniola offshore margin. Here we present preliminary results focused on the identification and characterization of recent tectonic features in the region and provide well-defined targets to carry out future studies for seismic and tsunamigenic hazard assessment.

  2. Plate Tectonics: From Initiation of Subduction to Global Plate Motions (Augustus Love Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Gurnis, Michael

    2013-04-01

    Plates are driven by buoyancy forces distributed in the mantle, within cooling oceanic plates (ridge push) and within subducted slabs. Although the case is often made that subducted slabs provide the principle driving force on plate motion, consensus has not been achieved. This is at least partially due to the great difficulty in realistically capturing the role of slabs in observationally-constrained models as slabs act to drive and resist plate motions through their high effective viscosity. Slab buoyancy acts directly on the edge of the plate (slab pull), while inducing mantle flow that tends to drag both subducting and overriding plates toward the trench. While plates bend during subduction they undergo a form of 'plastic failure' (as evident through faulting, seismicity and reduction of flexural parameters at the outer trench wall). The birth of a new subduction zone, subduction initiation, provides important insight into plate motions and subduction dynamics. About half of all subduction zones initiated over the Cenozoic and the geophysical and geological observations of them provide first order constraints on the mechanics of how these margins evolved from their preexisting tectonic state to self-sustaining subduction. We have examples of subduction initiation at different phases of the initiation process (e.g. early versus late) as well as how margins have responded to different tectonic forcings. The consequences of subduction initiation are variable: intense trench roll back and extensive boninitic volcanism followed initiation of the Izu-Bonin-Mariana arc while both were absent during Aleutian arc initiation. Such differences may be related to the character of the preexisting plates, the size of and forces on the plates, and how the lithosphere was initially bending during initiation. I will address issues associated with the forces driving plate tectonics and initiating new subduction zones from two perspectives. A common thread is the origin and

  3. "Dynamic Kinematics": Towards Linking Earth's Plate Motions to the Evolution of Global Mantle Flow

    NASA Astrophysics Data System (ADS)

    Rolf, T.; Tackley, P. J.

    2014-12-01

    The theory of plate tectonics has been one of the major breakthroughs in solid-Earth science and is capable of explaining many of the tectonic processes on present-day Earth. Moreover, it allows us to reconstruct Earth's tectonic history back until times of the supercontinent Pangaea and thus improves our understanding how Earth developed to its present state. However, plate tectonics remains a kinematic theory that does not sufficiently incorporate the balance of forces in the Earth's mantle and can thus not explain the motion of Earth's tectonic plates in a dynamically consistent manner. Here, we use fully dynamic models of mantle convection in global spherical geometry to overcome this issue. These models include tectonic plates self-consistently evolving from mantle flow (using a viscoplastic rheology) as well as continental drift. We analyze the evolution of plate velocities over time periods considerably longer than those covered by modern plate reconstructions. We observe significant changes in plate velocity magnitude and direction over timescales relevant for the Earth. While some of these plate reorganizations appear to be rather local affecting only very few plates, others seem to have more global consequences. We characterize the variety of different reorganizations based on features of modeled spreading centers and subduction zones, for instance the flux of slab material into the lower mantle. Initial results suggest that global changes in plate configuration correlate with phases of major slab penetration into the lower mantle, while changes on individual plate-scale do not necessarily do so.

  4. Effect of combined particle-phase diffusivity and viscosity on the compressible boundary layer of a particulate suspension over a flat plate

    SciTech Connect

    Chamkha, A.J.

    1999-05-01

    Boundary layer flow and heat transfer of pure and contaminated fluids have been an attractive research area for many investigators for many years due to its direct application in the aerospace, automotive, petroleum, geothermal, and many other industries. Here, a mathematical dilute fluid-particle suspension model governing steady, laminar, compressible, boundary layer flow and heat transfer over a semi-infinite flat plate based on the Eulerian or continuum approach is developed. The model accounts for both particulate viscous and diffusive effects. Both the fluid and the particle phases are assumed to have general power-law viscosity-temperature relations. For the case of finite particle-phase viscosity, a general boundary condition borrowed from rarefied gas dynamics is used for the particle phase at the surface. Uniform and nonuniform particle-phase slip coefficients are investigated. Numerical solution of the governing equations is obtained by an implicit, iterative, tridiagonal finite difference method. Graphical results for the displacement thicknesses and skin-friction coefficients of both phases as well as the wall heat transfer are presented for various parametric conditions.

  5. Plate-mantle coupling from post-Pangea plate kinematics

    NASA Astrophysics Data System (ADS)

    Zahirovic, Sabin; Dietmar Müller, R.; Seton, Maria; Flament, Nicolas

    2015-04-01

    keels impinge on asthenospheric flow to increase shear traction, thus anchoring the plate in the more viscous mantle transition zone. However, plates with significant cratonic fragments exhibit short-lived (~10 Myr) accelerations, such as the rapid motion of the Indian plate that is correlated with plume head arrivals as recorded by large igneous province (LIPs) emplacement, highlighting the necessity to analyse plate velocities over long geological timeframes. By evaluating factors controlling plate velocities in the post-Pangea timeframe, simple principles can be applied to highlight potential plate velocity artefacts for Paleozoic and earlier times for which no hotspot tracks, nor in-situ seafloor spreading histories, are preserved. Based on the post-Pangea timeframe, a principle that can be applied to pre-Pangea times is that plates with less than ~50% continental area can reach RMS velocities of ~20 cm/yr, while plates with more than 50% continental fraction do not exceed RMS velocities of ~10 cm/yr. Similarly, plates with large portions of continental or cratonic area with RMS velocities exceeding ~15 cm/yr for more than ~10 Myr should be flagged as potential artefacts requiring further justification of plate driving forces in such scenarios.

  6. Two mechanisms of rephasal of circadian rhythms in response to a 180 deg phase shift /simulated 12-hr time zone change/

    NASA Technical Reports Server (NTRS)

    Deroshia, C. W.; Winget, C. M.; Bond, G. H.

    1976-01-01

    A model developed by Wever (1966) is considered. The model describes the behavior of circadian rhythms in response to photoperiod phase shifts simulating time zone changes, as a function of endogenous periodicity, light intensity, and direction of phase shift. A description is given of an investigation conducted to test the model upon the deep body temperature rhythm in unrestrained subhuman primates. An evaluation is conducted regarding the applicability of the model in predicting the type and duration of desynchronization induced by simulated time zone changes as a function of endogenous periodicity.

  7. Direct observation of phase transformations in the simulated heat-affected zone of a 9Cr martensitic steel

    SciTech Connect

    Mayr, Peter; Palmer, T. A.; Elmer, J. W.; Specht, Eliot D

    2008-01-01

    An experimental test melt of a boron alloyed 9Cr-3W-3Co-V,Nb steel for high temperature applications in the thermal power generation industry was produced by vacuum induction melting. This grade of steel typically displays a homogeneous tempered martensitic microstructure in the as-received condition. However, after welding, this microstructure is significantly altered, resulting in a loss of its desired properties. The phase transformations during simulated thermal cycles typical of those experienced in the weld heat-affected zone (HAZ) were directly observed by in situ X-ray diffraction experiments using synchrotron radiation. Heating rates of 10 C s-1 and 100 C s-1 up to a peak temperature of 1300 C are investigated here. The final microstructures observed after both simulated weld thermal cycles are primarily composed of martensite with approximately 4% retained delta ferrite and 4% retained austenite, by volume. With the temporal resolution of the in situ X-ray diffraction technique, phase transformations from tempered martensite to austenite to delta ferrite during heating and to martensite during cooling were monitored. With this technique, the evolution of the final microstructure through both heating and cooling is monitored, providing additional context to the microstructural observations.

  8. Development of Hydrologic Characterization Technology of Fault Zones -- Phase I, 2nd Report

    SciTech Connect

    Karasaki, Kenzi; Onishi, Tiemi; Black, Bill; Biraud, Sebastien

    2009-03-31

    This is the year-end report of the 2nd year of the NUMO-LBNL collaborative project: Development of Hydrologic Characterization Technology of Fault Zones under NUMO-DOE/LBNL collaboration agreement, the task description of which can be found in the Appendix 3. Literature survey of published information on the relationship between geologic and hydrologic characteristics of faults was conducted. The survey concluded that it may be possible to classify faults by indicators based on various geometric and geologic attributes that may indirectly relate to the hydrologic property of faults. Analysis of existing information on the Wildcat Fault and its surrounding geology was performed. The Wildcat Fault is thought to be a strike-slip fault with a thrust component that runs along the eastern boundary of the Lawrence Berkeley National Laboratory. It is believed to be part of the Hayward Fault system but is considered inactive. Three trenches were excavated at carefully selected locations mainly based on the information from the past investigative work inside the LBNL property. At least one fault was encountered in all three trenches. Detailed trench mapping was conducted by CRIEPI (Central Research Institute for Electric Power Industries) and LBNL scientists. Some intriguing and puzzling discoveries were made that may contradict with the published work in the past. Predictions are made regarding the hydrologic property of the Wildcat Fault based on the analysis of fault structure. Preliminary conceptual models of the Wildcat Fault were proposed. The Wildcat Fault appears to have multiple splays and some low angled faults may be part of the flower structure. In parallel, surface geophysical investigations were conducted using electrical resistivity survey and seismic reflection profiling along three lines on the north and south of the LBNL site. Because of the steep terrain, it was difficult to find optimum locations for survey lines as it is desirable for them to be as

  9. Welcome to the Twilight Zone: a forgotten early phase of human evolutionary studies.

    PubMed

    Delisle, Richard G

    2012-06-01

    The field of paleoanthropology arose out of a strange and unacknowledged early phase of development prior to about the 1930s. It is often assumed that a key pillar of the discipline, the unity of humankind--the notion that humans are clearly separated phylogenetically (genealogically) from other non-human primates--was widely accepted from the inception of paleoanthropology around 1860. However, a final consensus on this fundamental question only appeared later on in the 20th century. This paper will focus on two key areas of disagreement, which reveal the unsettled state of this question during this early period: the question of uncertainty with respect to the number, identity and boundary of primate species (including humans) which prevailed in the 18th, 19th and early 20th centuries; and the matter of uncertainty with respect to the nature of the phylogenetic relationships among the various human populations and the other primate species which prevailed between 1864 and 1931. Consideration of these matters reveals that the modern research structure that paleoanthropologists take for granted today is much more recent than believed. PMID:22305470

  10. Fiscal Year 2009 Phased Construction Completion Report for EU Z2-36 in Zone 2, East Tennessee Technology Park, Oak Ridge, Tennessee

    SciTech Connect

    Bechtel Jacobs

    2009-02-10

    The purpose of this Phased Construction Completion Report (PCCR) is to present fiscal year (FY) 2009 results of Dynamic Verification Strategy (DVS) characterization activities for exposure unit (EU) Z2-36 in Zone 2 at the East Tennessee technology Park (ETTP). The ETTP is located in the northwest corner of the US Department of Energy (DOE) Oak Ridge Reservation in Oak Ridge, Tennessee and encompasses approximately 5000 acres that have been subdivided into three zones--Zone 1 ({approx} 1400 acres), Zone 2 ({approx} 800 acres), and the Boundary Area ({approx} 2800 acres). Zone 2 comprises the highly industrial portion of ETTP and consists of all formerly secured areas of the facility, including the large processing buildings and direct support facilities; experimental laboratories and chemical and materials handling facilities; materials storage and waste disposal facilities; secure document records libraries; and shipping and receiving warehouses. The Record of Decision for Soil, Buried Waste, and Subsurface Structure Actions in Zone 2, East Tennessee Technology Park, Oak Ridge, Tennessee (DOE 2005) (Zone 2 ROD) specifies the future end use for Zone 2 acreage as uncontrolled industrial for the upper 10 ft of soils. Characterization activities in these areas were conducted in compliance with the Zone 2 ROD and the DVS and data quality objectives (DQOs) presented in the Main Plant Group DQO Scoping Package (July 2006) and the Remedial Design Report/Remedial Action Work Plan for Zone 2 Soils, Slabs, and Subsurface Structures, East Tennessee Technology Park, Oak Ridge, Tennessee (DOE 2007a) (Zone 2 RDR/RAWP). The purpose of this PCCR is to address the following: (1) Document EU Z2-36 DVS characterization results; (2) Describe and document the risk evaluation and determine if the EU meets the Zone 2 ROD requirements for unrestricted industrial use to 10 ft bgs, and (3) Identify additional areas not defined in the Zone 2 ROD that require remediation based on the DVS

  11. Rheology linked with phase changes as recorded by development of shear bands in the South Armorican Shear Zone

    NASA Astrophysics Data System (ADS)

    Jeřábek, Petr; Bukovská, Zita

    2015-04-01

    The South Armorican Shear Zone in France represents a major right-lateral strike slip shear zone formed in the late stages of Variscan orogeny. The active deformation in this shear zone is associated with the development of S-C fabrics in granitoids where thin shear bands (C) overprint an earlier higher grade metamorphic foliation (S). In the studied samples covering low to high intensity of shear band overprint, we identified three stages of shear band evolution associated with distinct microstructures and deformation mechanisms. The initiation of shear bands stage I is associated with the formation of microcracks crosscutting the S fabric and detected namely in the recrystallized quartz aggregates. The microcracks of suitable orientation are filled by microcline, albite, muscovite and chlorite which is a typical assemblage also for the well developed shear bands. Phase equilibrium modeling in PERPLEX indicates that this assemblage formed at pressure-temperature range of 0.1-0.4 GPa and 300-340 °C. Stage II of shear band evolution is characterized by dynamic recrystallization and grain size reduction of quartz aggregates along the microcracks and replacement of quartz by microcline along grain boundaries. This process leads to disintegration of quartz aggregate fabric and phase mixing in the shear bands. The inferred deformation mechanism for this stage is solution-precipitation creep although recrystallization of quartz is still active at the contact between quartz aggregates and shear bands. The coarse grained microstructure of quartz aggregates with ca ~250 microns average grain size reduces to ~10 microns grain size when recrystallized along extremely thin shear bands/microcracks and to ~20 microns grain size when recrystallized along the thicker shear bands. By using the flow law of Patterson and Luan (1990) for dislocation creep in quartz and the quartz piezometer of Stipp and Tullis (2003) corrected after Holyoke and Kronenberg (2010), the quartz

  12. Observation of Phase Objects by Using an X-ray Microscope with a Foucault Knife-Edge

    SciTech Connect

    Watanabe, N.; Sasaya, T.; Imai, Y.; Iwata, S.; Zama, K.; Aoki, S.

    2011-09-09

    An x-ray microscope with a zone plate was assembled at the synchrotron radiation source of BL3C, Photon Factory. A Foucault knife-edge was set at the back focal plate of the objective zone plate and phase retrieval was tested by scanning the knife-edge. A preliminary result shows that scanning the knife-edge during exposure was effective for phase retrieval. Phase-contrast tomography was investigated using differential projection images calculated from two Schlieren images with the oppositely oriented knife-edges. Fairly good reconstruction images of polystyrene beads and spores could be obtained.

  13. Observation of Phase Objects by Using an X-ray Microscope with a Foucault Knife-Edge

    NASA Astrophysics Data System (ADS)

    Watanabe, N.; Sasaya, T.; Imai, Y.; Iwata, S.; Zama, K.; Aoki, S.

    2011-09-01

    An x-ray microscope with a zone plate was assembled at the synchrotron radiation source of BL3C, Photon Factory. A Foucault knife-edge was set at the back focal plate of the objective zone plate and phase retrieval was tested by scanning the knife-edge. A preliminary result shows that scanning the knife-edge during exposure was effective for phase retrieval. Phase-contrast tomography was investigated using differential projection images calculated from two Schlieren images with the oppositely oriented knife-edges. Fairly good reconstruction images of polystyrene beads and spores could be obtained.

  14. Characterizing the intracrustal low velocity zone beneath northwest India-Asia collision zone

    NASA Astrophysics Data System (ADS)

    Hazarika, Devajit; Sen, Koushik; Kumar, Naresh

    2014-12-01

    Teleseismic data recorded at 13 broad-band seismological stations across northwest part of the Tethyan Himalaya and eastern Ladakh are analysed to determine the seismic characteristics of the crust and upper mantle beneath the northwest India-Asia collision zone. The receiver functions computed from teleseismic P-waveform for a wide range of backazimuth show strong azimuthal variation in the Indus suture zone (ISZ), the zone which marks the collision and subsequent subduction of both the Tethyan oceanic plate and Indian continental plate beneath Eurasia. The teleseismic waves piercing the ISZ do not show clear P-to-S (Ps) converted phase at the depth of Moho. In contrast, the waves piercing the Karakoram zone, Ladakh batholith and the Tethyan Himalayan region south of the ISZ clearly show the Moho converted Ps phase and corresponding inverted models reveal variation of crustal thickness from ˜60 km beneath the Tethyan Himalaya to ˜80 km beneath the Karakoram fault zone. A prominent intracrustal low velocity zone (IC-LVZ) is detected in the shear wave velocity models within the depth range ˜15-40 km. The IC-LVZ identified at the stations both north and south of the ISZ can be interpreted as due to presence of fluid/partial melt. Our study provides compelling evidence that the mid-crustal low velocity zone does extend across the suture zone, in to the Tethyan Himalaya. The contact between this serpentinized ultramafic rocks and the eclogitized Indian continental crust in the suture zone is identified at ˜47-50 km depth.

  15. The Influence of Temperature on Fault Strength and the Base of the Crustal Seismogenic Zone along the Pacific-North American Plate Boundary

    NASA Astrophysics Data System (ADS)

    Williams, C. F.

    2008-12-01

    A fundamental property of crustal seismicity is the depth confinement of earthquake nucleation. Although the frictional stability of seismogenic faults is a complex phenomenon with limited experimental evidence to constrain it, an important feature of the seismic-aseismic transition along the San Andreas and subsidiary fault systems in California is the consistency of temperature as the primary control, with the transition temperature averaging a relatively constant 350 to 400 °C over a fairly wide depth range (5 to 25 km) at many different locations. Along the active faults characterized by this constant transition temperature, the base of the seismogenic zone as defined by background seismicity is generally within approximately 2 km of the depth of hypocenters for significant earthquakes (e.g., 1971 M6.6 San Fernando, 1983 M6.4 Coalinga, 1984 M6.2 Morgan Hill, 1987 M5.9 Whittier Narrows, 1989 M6.9 Loma Prieta, 1992 M6.1 Joshua Tree, and 1994 M6.7 Northridge earthquakes). However, the fault zones ruptured by the 1992 M7.3 Landers, 1999 M7.1 Hector Mine and 2004 M6.0 Parkfield earthquakes deviate from this pattern in two potentially significant ways. First, the base of seismicity for these earthquakes appears to occur at a lower temperature (300 to 350 °C for Parkfield and less than 300 °C for Landers and Hector Mine). Second, for all three earthquakes the nucleation point of the main shock is on the order of 5 km shallower than the observed base of seismicity. Taken together, these two sets of observations indicate that the strength of the fault segments involved in these three earthquakes may not reach a maximum near the base of the seismogenic zone and that frictional stability on these fault segments is controlled by a combination of processes or properties of which temperature is only one, possibly less important, factor. Results from the recent SAFOD scientific drilling project highlight the potential role of serpentinite-rich fault gouge in altering fault

  16. Seismicity and Plate Geometry of the Mendocino Triple Junction Region, Northern California (1986-2006)

    NASA Astrophysics Data System (ADS)

    McPherson, B. C.; Pryor, I. S.; Williams, T. B.

    2007-12-01

    The Mendocino triple junction is an unstable triple junction located at the convergence of the North American (NAP), Pacific, and Gorda lithospheric plates near Cape Mendocino, northern California. Thirty years of seismic data (1976 - 2006) was analyzed to characterize plate geometry and stress orientations affecting the region. A simple 3-D model of plate geometry was developed to separate earthquake events occurring in the NAP or Gorda plate. Upper- hemisphere focal mechanism solutions were hand plotted for select earthquake events in the study area. NAP solutions north of the MTJ are primarily reverse mechanisms. P and T axes for these solutions indicate north-northeast (~N45E) directed pressure consistent with geodetic and geologic data. NAP solutions south of the MTJ are strike-slip solutions consistent with northwest striking faults of the northern San Andreas fault zone. Gorda plate solutions east of the MTJ are primarily normal fault solutions indicating downslab tension in the subducting plate. East-west cross section plots indicate a very dense cloud of seismicity at the MTJ and demonstrate a shallow dip angle (~8° - 12°) for the top of the Gorda plate to longitude 123.5 W. East of this longitude dip angle increases and Gorda plate seismicity phases out. North-south cross sections show a clear gap in seismicity coincident with an interpreted southern extent of the Gorda plate at latitude 40.25 N as well as the aseismic nature of both the Pacific plate and northern San Andreas fault proper.

  17. ⁵⁷Fe polarization-dependent synchrotron Mössbauer spectroscopy using a diamond phase plate and an iron borate nuclear Bragg monochromator.

    PubMed

    Mitsui, Takaya; Imai, Yasuhiko; Masuda, Ryo; Seto, Makoto; Mibu, Ko

    2015-03-01

    Energy-domain (57)Fe polarization-dependent synchrotron radiation Mössbauer spectroscopy was developed by using a diamond X-ray phase plate and an iron borate nuclear Bragg monochromator. The former controls the polarization of the incident synchrotron radiation X-rays and the latter filters the (57)Fe-Mössbauer radiation with a narrow bandwidth of ∼3.4 Γ0 (Γ0 ≃ 4.7 neV: natural linewidth of the (57)Fe nucleus) from the broadband synchrotron radiation. The developed nuclear diffraction optics allowed (57)Fe-Mössbauer studies to be performed with various polarization states, i.e. linear polarization, circular polarization and non-polarization. In this paper, the spectrometer system, beam characterization, performance-test experiments and a grazing-incidence Mössbauer measurement of an isotope-enriched ((57)Fe: 95%) iron thin film are described. PMID:25723944

  18. Effect of soil moisture dynamics on dense nonaqueous phase liquid (DNAPL) spill zone architecture in heterogeneous porous media.

    PubMed

    Yoon, Hongkyu; Valocchi, Albert J; Werth, Charles J

    2007-03-20

    The amount, location, and form of NAPL in contaminated vadose zones are controlled by the spatial distribution of water saturation and soil permeability, the NAPL spill scenario, water infiltration events, and vapor transport. To evaluate the effects of these processes, we used the three-phase flow simulator STOMP, which includes a new permeability-liquid saturation-capillary pressure (k-S-P) constitutive model. This new constitutive model considers three NAPL forms: free, residual, and trapped. A 2-D vertical cross-section with five stratigraphic layers was assumed, and simulations were performed for seven cases. The conceptual model of the soil heterogeneity was based upon the stratigraphy at the Hanford carbon tetrachloride (CT) spill site. Some cases considered co-disposal of NAPL with large volumes of wastewater, as also occurred at the Hanford CT site. In these cases, the form and location of NAPL were most strongly influenced by high water discharge rates and NAPL evaporation to the atmosphere. In order to investigate the impact of heterogeneity, the hydraulic conductivity within the lower permeability layer was modeled as a realization of a random field having three different classes. For six extreme cases of 100 realizations, the CT mass that reached the water table varied by a factor of two, and was primarily controlled by the degree of lateral connectivity of the low conductivity class within the lowest permeability layer. The grid size at the top boundary had a dramatic impact on NAPL diffusive flux just after the spill event when the NAPL was present near the ground surface. NAPL evaporation with a fine grid spacing at the top boundary decreased CT mass that reached the water table by 74%, compared to the case with a coarse grid spacing, while barometric pumping had a marginal effect for the case of a continuous NAPL spill scenario considered in this work. For low water infiltration rate scenarios, the distribution of water content prior to a NAPL

  19. Tectonics of the Easter plate

    NASA Technical Reports Server (NTRS)

    Engeln, J. F.; Stein, S.

    1984-01-01

    A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

  20. Fiscal Year 2007 Phased Construction Completion Report for the Zone 2 Soils, Slabs, and Subsurface Structures at East Tennessee Technology Park, Oak Ridge, Tennessee

    SciTech Connect

    RSI

    2008-03-01

    The purpose of this Phased Construction Completion Report (PCCR) is to present the fiscal year (FY) 2007 results of characterization activities and recommended remedial actions (RAs) for 11 exposure units (EUs) in Zone 2 (Z2-01, Z2-03, Z2-08, Z2-23, Z2-24, Z2-28, Z2-34, Z2-37, Z2-41, Z2-43, and Z2-44) at the East Tennessee Technology Park (ETTP), which is located in the northwest corner of the U.S. Department of Energy (DOE) Oak Ridge Reservation in Oak Ridge, Tennessee (Fig. 1). ETTP encompasses a total land area of approximately 5000 acres that has been subdivided into three zones--Zone 1 ({approx}1400 acres), Zone 2 ({approx}800 acres), and the Boundary Area ({approx}2800 acres). Zone 2, which encompasses the highly industrialized portion of ETTP shown in Fig. 1, consists of all formerly secured areas of the facility, including the large processing buildings and direct support facilities; experimental laboratories and chemical and materials handling facilities; materials storage and waste disposal facilities; secure document records libraries; and shipping and receiving warehouses. The Zone 2 Record of Decision for Soil, Buried Waste, and Subsurface Structure Actions in Zone 2, East Tennessee Technology Park, Oak Ridge, Tennessee (DOE 2005) (Zone 2 ROD) specifies the future end use for Zone 2 acreage as uncontrolled industrial for the upper 10 ft of soils. Characterization activities in these areas were conducted in compliance with the Zone 2 ROD and the Dynamic Verification Strategy (DVS) and data quality objectives (DQOs) presented in the Remedial Design Report/Remedial Action Work Plan for Zone 2 Soils, Slabs, and Subsurface Structures, East Tennessee Technology Park, Oak Ridge, Tennessee (DOE 2007) (Zone 2 RDR/RAWP). The purpose of this PCCR is to address the following: (1) Document DVS characterization results for the accessible EUs in FY 2007; (2) Describe and document the risk evaluation for each EU, and determine if the EU met the Zone 2 ROD requirements

  1. Accretion and Subduction of Oceanic Lithosphere: 2D and 3D Seismic Studies of Off-Axis Magma Lenses at East Pacific Rise 9°37-40'N Area and Downgoing Juan de Fuca Plate at Cascadia Subduction Zone

    NASA Astrophysics Data System (ADS)

    Han, Shuoshuo

    Two thirds of the Earth's lithosphere is covered by the ocean. The oceanic lithosphere is formed at mid-ocean ridges, evolves and interacts with the overlying ocean for millions of years, and is eventually consumed at subduction zones. In this thesis, I use 2D and 3D multichannel seismic (MCS) data to investigate the accretionary and hydrothermal process on the ridge flank of the fast-spreading East Pacific Rise (EPR) at 9°37-40'N and the structure of the downgoing Juan de Fuca plate at the Cascadia subduction zone offshore Oregon and Washington. Using 3D multichannel seismic (MCS) data, I image a series of off-axis magma lenses (OAML) in the middle or lower crust, 2-10 km from the ridge axis at EPR 9°37-40'N. The large OAMLs are associated with Moho travel time anomalies and local volcanic edifices above them, indicating off-axis magmatism contributes to crustal accretion though both intrusion and eruption (Chapter 1). To assess the effect of OAMLs on the upper crustal structure, I conduct 2-D travel time tomography on downward continued MCS data along two across-axis lines above a prominent OAML in our study area. I find higher upper crustal velocity in a region ~ 2 km wide above this OAML compared with the surrounding crust. I attribute these local anomalies to enhanced precipitation of alteration minerals in the pore space of upper crust associated with high-temperature off-axis hydrothermal circulation driven by the OAML (Chapter 2). At Cascadia, a young and hot end-member of the global subduction system, the state of hydration of the downgoing Juan de Fuca (JdF) plate is important to a number of subduction processes, yet is poorly known. As local zones of higher porosity and permeability, faults constitute primary conduits for seawater to enter the crust and potentially uppermost mantle. From pre-stack time migrated MCS images, I observe pervasive faulting in the sediment section up to 200 km from the deformation front. Yet faults with large throw and

  2. Physical metallurgical basis for heat-affected zone and base-plate properties of a microalloyed HSLA steel. Final report 1984-1986

    SciTech Connect

    Nichting, R.A.; Brown, E.L.

    1986-12-01

    The overall objective of this study was to elucidate the processing structure/property relationship associated with the heat-affected zone (HAZ) produced in an HSLA microalloyed steel during arc welding. Single-pass submerged arc welds on a Nb-V microalloyed steel were made with variable heat input. The thermal cycle as a function of heat input and position in the HAZ was determined experimentally in the course of welding. In addition, weld simulations were produced for selected heat inputs and HAZ locations. The evolution of austenite and transformation product microstructure as well as the state of microalloy precipitation was monitored as a function of heat input and HAZ location primarily via light and electron microscopy on specimens from actual welds and simulation specimens. These observations were utilized to support efforts to model austenite microstructure evolution and continuous-cooling transformation behavior in the HAZ. Charpy-impact-toughness testing was performed on actual weld HAZ specimens and specimens of selected simulation specimens. Impact transition curves were determined, and the microsctructure through which fracture propagated was correlated with impact transition energies and fracture surface morphology determined via scanning electron microscopy.

  3. Using nonlinear forecasting to learn the magnitude and phasing of time-varying sediment suspension in the surf zone

    USGS Publications Warehouse

    Jaffe, B.E.; Rubin, D.M.

    1996-01-01

    complete description of the dynamical forcing of the flow (including accelerations and wave phase and shape) responsible for sediment suspension. Incorporating such a velocity history and a lag time into the formulation of the forcing for time-dependent models for sediment suspension in the surf zone will greatly increase our ability to predict suspended-sediment transport.

  4. San Andres Rift, Nicaraguan Shelf: A 346-Km-Long, North-South Rift Zone Actively Extending the Interior of the "Stable" Caribbean Plate

    NASA Astrophysics Data System (ADS)

    Carvajal, L. C.; Mann, P.

    2015-12-01

    The San Andres rift (SAR) is an active, 015°-trending, bathymetric and structural rift basin that extends for 346 km across the Nicaraguan platform and varies in bathymetric width from 11-27 km and in water depth from 1,250 to 2,500 m. We used four 2D regional seismic lines tied to two offshore, industry wells located west of the SAR on the Nicaraguan platform to map normal faults, transfer faults, and possibly volcanic features with the rift. The Colombian islands of San Andres (26 km2) and Providencia (17 km2) are footwall uplifts along west-dipping, normal fault bounding the eastern margin of the rift. Mapping indicates the pre-rift section is Late Cretaceous to Oligocene in age and that the onset of rifting began in the early to middle Miocene as shown by wedging of the Miocene and younger sedimentary fill controlled by north-south-striking normal faults. Structural restorations at two locations across the rift shows that the basin opened mainly by dip-slip fault motions producing a total, east-west extension of 18 km in the north and 15 km in the south. Structural restoration shows the rift formed on a 37-km-wide, elongate basement high - possibly of late Cretaceous, volcanic origin and related to the Caribbean large igneous province. Previous workers have noted that the SAR is associated with province of Pliocene to Quaternary seamounts and volcanoes which range from non-alkaline to mildly alkaline, including volcanic rocks on Providencia described as andesites and rhyolites. The SAR forms one of the few recognizable belts of recorded seismicity within the Caribbean plate. The origin of the SAR is related to Miocene and younger left-lateral displacement along the Pedro Banks fault to the north and the southwestern Hess fault to the south. We propose that the amount of left-lateral displacement that created the rift is equivalent to the amount of extension that formed it: 18-20 km.

  5. Thermal Models of the Costa Rica - Nicaragua Subduction Zone: the Effect of a Three-Dimensional Oceanic Plate Structure and Hydrothermal Circulation in the Temperature Distribution and Mantle Wedge Dynamics

    NASA Astrophysics Data System (ADS)

    Rosas, J. C.; Currie, C. A.; He, J.

    2014-12-01

    Over the last years several 2D thermo-mechanical models of the Costa Rica - Nicaragua Subduction Zone (CNSZ) have studied the thermal distribution of sections of the fault. Such investigations allow us to understand temperature-related aspects of subduction zones, like volcanism and megathrust earthquake locations. However, certain features of the CNSZ limit the range of applicability of 2D models. In the CNSZ, geochemical trends and seismic anisotropy studies reveal a 3D mantle wedge flow that departs from the 2D corner flow. The origin of this flow are dip variations (20o to 25o between Nicaragua and Costa Rica) and the presence of a slab window in Panama that allows material to flow into the mantle wedge. Also, the Central America trench has abrupt variations in surface heat flux that contrasts with steady changes in plate age and convergence rate. These variations have been attributed to hydrothermal circulation (HC), which effectively removes heat from the oceanic crust.In this project we analyze the thermal structure of the CNSZ. The objective is to study dehydration and metamorphic reactions, as well as the length of the megathrust seismogenic zone. We created 3D finite-element models that employ a dislocation creep rheology for the mantle wedge. Two aspects make our models different from previous studies: an up-to-date 3D slab geometry, and an implementation of HC by introducing a conductive proxy in the subducting aquifer, allowing us to model convective heat transport without the complex, high-Rayleigh number calculations. A 3D oceanic boundary condition that resembles the along-strike changes in surface heat flux is also employed. Results show a maximum mantle wedge flow rate of 4.69 cm/yr in the along-strike direction, representing more than 50% of the slab convergence rate. With respect to 2D models, analysis shows this flow changes temperatures by ~100 C in the mantle wedge near areas of strong slab curvature. Along the subducting interface, there is

  6. Effect of simulated thermal cycles on the microstructure of the heat-affected zone in HSLA-80 and HSLA-100 steel plates

    NASA Astrophysics Data System (ADS)

    Shome, M.; Gupta, O. P.; Mohanty, O. N.

    2004-03-01

    The influence of weld thermal simulation on the transformation kinetics and heat-affected zone (HAZ) microstructure of two high-strength low-alloy (HSLA) steels, HSLA-80 and HSLA-100, has been investigated. Heat inputs of 10 kJ/cm (fast cooling) and 40 kJ/cm (slow cooling) were used to generate single-pass thermal cycles with peak temperatures in the range of 750 °C to 1400 °C. The prior-austenite grain size is found to grow rapidly beyond 1100 °C in both the steels, primarily with the dissolution of niobium carbonitride (Nb(CN)) precipitates. Dilatation studies on HSLA-80 steel indicate transformation start temperatures (T s ) of 550 °C to 560 °C while cooling from a peak temperature (T p ) of 1000 °C. Transmission electron microscopy studies show here the presence of accicular ferrite in the HAZ. The T s value is lowered to 470 °C and below when cooled from a peak temperature of 1200 °C and beyond, with almost complete transformation to lath martensite. In HSLA-100 steel, the T s value for accicular ferrite is found to be 470 °C to 490 °C when cooled from a peak temperature of 1000 °C, but is lowered below 450 °C when cooled from 1200 °C and beyond, with correspondingly higher austenite grain sizes. The transformation kinetics appears to be relatively faster in the fine-grained austenite than in the coarse-grained austenite, where the niobium is in complete solid solution. A mixed microstructure consisting of accicular ferrite and lath martensite is observed for practically all HAZ treatments. The coarse-grained HAZ (CGHAZ) of HSLA-80 steel shows a higher volume fraction of lath martensite in the final microstructure and is harder than the CGHAZ of HSLA-100 steel.

  7. Phase separation in a binary mixture confined between symmetric parallel plates: Capillary condensation transition near the bulk critical point

    NASA Astrophysics Data System (ADS)

    Yabunaka, Shunsuke; Okamoto, Ryuichi; Onuki, Akira

    2013-03-01

    We investigate phase separation of near-critical binary mixtures between parallel symmetric walls in the strong adsorption regime. We take into account the renormalization effect due to the critical fluctuations using the recent local functional theory [Okamoto and Onuki, J. Chem. Phys.0021-960610.1063/1.3693331 136, 114704 (2012)]. In statics, a van der Waals loop is obtained in the relation between the average order parameter <ψ> in the film and the chemical potential when the temperature T is lower than the film critical temperature Tcca (in the case of an upper critical solution temperature). In dynamics, we lower T below the capillary condensation line from above Tcca. We calculate the subsequent time development assuming no mass exchange between the film and the reservoir. In the early stage, the order parameter ψ changes only in the direction perpendicular to the walls. For sufficiently deep quenching, such one-dimensional profiles become unstable with respect to the fluctuations varying in the lateral directions. The late-stage coarsening is then accelerated by the hydrodynamic interaction. A pancake domain of the phase disfavored by the walls finally appears in the middle of the film.

  8. Fault Zone Guided Wave generation on the locked, late interseismic Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Eccles, J. D.; Gulley, A. K.; Malin, P. E.; Boese, C. M.; Townend, J.; Sutherland, R.

    2015-07-01

    Fault Zone Guided Waves (FZGWs) have been observed for the first time within New Zealand's transpressional continental plate boundary, the Alpine Fault, which is late in its typical seismic cycle. Ongoing study of these phases provides the opportunity to monitor interseismic conditions in the fault zone. Distinctive dispersive seismic codas (~7-35 Hz) have been recorded on shallow borehole seismometers installed within 20 m of the principal slip zone. Near the central Alpine Fault, known for low background seismicity, FZGW-generating microseismic events are located beyond the catchment-scale partitioning of the fault indicating lateral connectivity of the low-velocity zone immediately below the near-surface segmentation. Initial modeling of the low-velocity zone indicates a waveguide width of 60-200 m with a 10-40% reduction in S wave velocity, similar to that inferred for the fault core of other mature plate boundary faults such as the San Andreas and North Anatolian Faults.

  9. The petrogenesis of the Early Permian Variscan granites of the Cornubian Batholith: Lower plate post-collisional peraluminous magmatism in the Rhenohercynian Zone of SW England

    NASA Astrophysics Data System (ADS)

    Simons, B.; Shail, Robin K.; Andersen, Jens C. Ø.

    2016-09-01

    The Early Permian Cornubian Batholith was generated during an extensional regime following Variscan convergence within the Rhenohercynian Zone of SW England. Its component granites can be classified, using mineralogical, textural and geochemical criteria, into five main types, all of which are peraluminous (A/CNK > 1.1): G1 (two-mica), G2 (muscovite), G3 (biotite), G4 (tourmaline) and G5 (topaz). G1 granites formed through up to 20% muscovite and minor biotite dehydration melting of a metagreywacke source at moderate temperatures and pressures (731-806 °C, > 5 kbar). Younger G3 granites formed through higher temperature, lower pressure (768-847 °C, < 4 kbar) biotite-dominated melting of a similar source. Partial melting was strongly influenced by the progressive lower-mid crustal emplacement of mafic igneous rocks during post-Variscan extension and a minor (< 5%-10%) mantle-derived component in the granites is possible. Two distinct fractionation series, G1-G2 and G3-G4, are defined using whole-rock geochemical and mineral chemical data. Variations in the major elements, Ba, Sr and Rb indicate that G1 and G3 granites underwent 15%-30% fractionation of an assemblage dominated by plagioclase, alkali feldspar and biotite to form more evolved G2 and G4 granites, respectively. Decreasing whole-rock abundances of Zr, Th and REE support the fractionation of zircon, monazite, apatite and allanite. Subsolidus alteration in G2 and G4 granites is indicated by non-primary muscovite and tourmaline and modification of major and trace element trends for G3-G4 granites, particularly for P2O5 and Rb. Topaz (G5) granites show low Zr, REE and extreme enrichment in Rb (up to 1530 ppm) and Nb (79 ppm) that cannot be related in a straightforward manner to continued differentiation of the G1-G2 or G3-G4 series. Instead, they are considered to represent partial melting, mediated by granulite facies fluids, of a biotite-rich restite following extraction of G1 and/or G3 magmas; they do

  10. Plasma-Enhanced Atomic Layer Deposition of Ruthenium-Titanium Nitride Mixed-Phase Layers for Direct-Plate Liner and Copper Diffusion Barrier Applications

    NASA Astrophysics Data System (ADS)

    Gildea, Adam James

    Current interconnect networks in semiconductor processing utilize a sputtered TaN diffusion barrier, Ta liner, and Cu seed to improve the adhesion, microstructure, and electromigration resistance of electrochemically deposited copper that fills interconnect wires and vias. However, as wire/via widths shrink due to device scaling, it becomes increasingly difficult to have the volume of a wire/via be occupied with ECD Cu which increases line resistance and increases the delay in signal propagation in IC chips. A single layer that could serve the purpose of a Cu diffusion barrier and ECD Cu adhesion promoter could allow ECD Cu to occupy a larger volume of a wire/via, leading to a decrease in line resistance and decrease in signal delay. Previous work has shown RuTaN, RuWCN, and RuCo films can act as Cu diffusion barriers and be directly platable to thickness of 2-3nm. However, other material selections may prove as effective or possibly better. Mixed-phase films of ruthenium titanium nitride grown by atomic layer deposition (ALD) were investigated for their performance as a Cu diffusion barrier and as a surface for the direct plating of ECD Cu. All Ru was deposited by plasma-enhanced atomic layer deposition (PEALD) while TiN was deposited by either thermal ALD or PEALD. RuTiN, films with thermal ALD TiN and a Ru:Ti of 20:1 showed barrier performance comparable to PVD TaN at 3-4 nm thickness and 15 nm planar films were directly platable. Follow up work is certainly needed for this material set, yet initial results indicate RuTiN could serve as an effective direct plate liner for Cu interconnects.

  11. Influence of overriding plate velocity changes on slab dip and deformation: insights from laboratory models

    NASA Astrophysics Data System (ADS)

    Guillaume, Benjamin; Hertgen, Solenn; Martinod, Joseph

    2016-04-01

    Over geological times,