WorldWideScience

Sample records for buoyancy-driven rapid exhumation

  1. Buoyancy-Driven Polymerase Chain Reaction (PCR) Devices

    Energy Technology Data Exchange (ETDEWEB)

    Ness, K D; Wheeler, E K; Benett, W; Stratton, P; Christian, A; Chen, A; Ortega, J; Weisgraber, T H; Goodson, K E

    2004-09-28

    Polymerase chain reaction (PCR) facilitates DNA detection by significantly increasing the concentration of specific DNA segments. A new class of PCR instruments uses a buoyancy-driven re-circulating flow to thermally cycle the DNA sample and benefits from reduced cycle times, low sample volumes, a miniaturized format, and low power consumption. This paper analyzes a specific buoyancy PCR device in a micro-channel ''race-track'' geometry to determine key parameters about PCR cycle times and other figures of merit as functions of device dimensions. The 1-D model balances the buoyancy driving force with frictional losses. A hydrostatic pressure imbalance concept is used between the left and right sides of the fluid loop to calculate the buoyancy driving force. Velocity and temperature distributions within the channels are determined from two-dimensional analysis of the channel section, with developing region effects included empirically through scaled values of the local Nusselt number. Good agreement between four independent verification steps validate the 1-D simulation approach: (1) analytical expressions for the thermal entrance length are compared against, (2) comparison with a full 3-D finite element simulation, (3) comparison with an experimental flow field characterization, and (4) calculation of the minimum PCR runtime required to get a positive PCR signal from the buoyancy-driven PCR device. The 1-D approach closely models an actual buoyancy-driven PCR device and can further be used as a rapid design tool to simulate buoyancy PCR flows and perform detailed design optimizations studies.

  2. Buoyancy driven turbulence and distributed chaos

    CERN Document Server

    Bershadskii, A

    2016-01-01

    It is shown, using results of recent direct numerical simulations, laboratory experiments and atmospheric measurements, that buoyancy driven turbulence exhibits a broad diversity of the types of distributed chaos with its stretched exponential spectrum $\\exp(-k/k_{\\beta})^{\\beta}$. The distributed chaos with $\\beta = 1/3$ (determined by the helicity correlation integral) is the most common feature of the stably stratified turbulence (due to the strong helical waves presence). These waves mostly dominate spectral properties of the vertical component of velocity field, while the horizontal component is dominated by the diffusive processes both for the weak and strong stable stratification ($\\beta =2/3$). For the last case influence of the low boundary can overcome the wave effects and result in $\\beta =1/2$ for the vertical component of the velocity field (the spontaneous breaking of the space translational symmetry - homogeneity). For the unstably stratified turbulence in the Rayleigh-Taylor mixing zone the di...

  3. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang

    2009-01-01

    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening...... and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, were measured. A bi-directional airflow rate was measured using the constant...... injection tracer gas technique. Smoke visualizations showed that the airflow patterns are highly transient and unstable, and that the airflow rate oscillates with time. Correlations between the Froude (Archimedes) number Fr (Ar) and the L/D ratio are presented. In some cases the measured airflow rates fit...

  4. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per

    2009-01-01

    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening...... and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, were measured. A bi-directional airflow rate was measured using the constant...... quite well with the Epstein's formula ratio are presented. In some cases the measured airflow rates fit quite well with the Epstein's formula but in other cases the measured data show clear deviations from the Epstein's formula. Thus, revised formulas for natural ventilation are proposed....

  5. Transient buoyancy-driven ventilation: Part 2. Modelling heat transfer

    OpenAIRE

    Steven D. Sandbach and Gregory F. Lane-Serff

    2011-01-01

    A new mathematical model for buoyancy-driven ventilation [Sandbach SD, Lane-Serif GF. Transient buoyancy-driven ventilation: Part 1. Modelling advection. Building and Environment, 2011] is modified to include heat transfer at the boundaries. Heat transfers at the ceiling and floor are included, using Newton's law of cooling to model convective heat transfer between the air and the solid boundaries, Fourier's law to model conductive heat transfer through the floor and ceiling, and a linear ver...

  6. Semi-Empirical Models for Buoyancy-Driven Ventilation

    DEFF Research Database (Denmark)

    Terpager Andersen, Karl

    2015-01-01

    A literature study is presented on the theories and models dealing with buoyancy-driven ventilation in rooms. The models are categorised into four types according to how the physical process is conceived: column model, fan model, neutral plane model and pressure model. These models are analysed a...

  7. Modelling and Linear Control of a Buoyancy-Driven Airship

    OpenAIRE

    Wu, Xiaotao,; Moog, Claude; Hu, Yueming

    2009-01-01

    We describe the modelling and control of a newkind airship which is propelled by buoyancy. Based on the Newton-Euler equations and Kirchhoff equations, and referred to the models of underwater gliders and aircraft, a 6DOF nonlinear mathematical model of a buoyancy-driven airship is derived, with features distributed internal mass, and no thrust, elevators and rudders. The attitudes are controlled by the motion of internal mass. The performances of the airship are studied in the vertical plane...

  8. Buoyancy Driven Mixing with Continuous Volumetric Energy Deposition

    Science.gov (United States)

    Wachtor, Adam J.; Jebrail, Farzaneh F.; Dennisen, Nicholas A.; Andrews, Malcolm J.; Gore, Robert A.

    2014-11-01

    An experiment involving a miscible fluid pair is presented which transitioned from a Rayleigh-Taylor (RT) stable to RT unstable configuration through continuous volumetric energy deposition (VED) by microwave radiation. Initially a light, low microwave absorbing fluid rested above a heavier, more absorbing fluid. The alignment of the density gradient with gravity made the system stable, and the Atwood number (At) for the initial setup was approximately -0.12. Exposing the fluid pair to microwave radiation preferentially heated the bottom fluid, and caused its density to drop due to thermal expansion. As heating of the bottom fluid continued, the At varied from negative to positive, and after the system passed through the neutral stability point, At = 0, buoyancy driven mixing ensued. Continuous VED caused the At to continue increasing and further drive the mixing process. Successful VED mixing required careful design of the fluid pair used in the experiment. Therefore, fluid selection is discussed, along with challenges and limitations of data collection using the experimental microwave facility. Experimental and model predictions of the neutral stability point, and onset of buoyancy driven mixing, are compared, and differences with classical, constant At RT driven turbulence are discussed.

  9. Experimental study of buoyancy driven natural ventilation through horizontal openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang

    2007-01-01

    An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening, respectiv......An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening......, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and that air flow rates oscillate with time. Correlations between the Froude number Fr and the L/D ratio...... of a ventilation system, but also be implemented in more detailed models, especially multi-zone models, for simulation of the performance of natural ventilation systems...

  10. Characteristics of Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Li, Zhigang

    through horizontal openings. Two cases of full-scale measurements of buoyancy driven natural ventilation through horizontal openings are performed: one horizontal opening and one horizontal opening combined with one vertical opening. For the case of one horizontal opening, the measurements are made...... for opening ratios L/D range from 0.027 to 4.455. The basic nature of air flow through the openings, including air flow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, are measured. Smoke visualizations show that the air flow patterns are highly...... transient, unstable and complex, and the air flow rates oscillate with time. Correlations between the Froude number Fr and the opening ratio L/D are obtained, which is reasonable agreement with Epstein's formula derived from brine-water measurements, but the obtained Fr values show considerable deviations...

  11. Field evidence for buoyancy-driven water flow in a Sphagnum dominated peat bog

    NARCIS (Netherlands)

    Adema, E.B.; Baaijens, G. J.; van Belle, J.; Rappoldt, C.; Grootjans, A. P.; Smolders, A. J. P.

    2006-01-01

    Nocturnal buoyancy-driven water flow in bogs is proposed as a mechanism to replenish the nutrient availability in the top of the acrotelm. In an earlier paper, we provided evidence for buoyancy-driven water flow on theoretical and experimental grounds. In this paper, field evidence is given for the

  12. Buoyancy-driven convection may switch between reactive states in three-dimensional chemical waves

    OpenAIRE

    Šebestíková, L. (Lenka); Hauser, M J B

    2012-01-01

    Traveling waves in an extended reactor, whose width cannot be neglected, represent a three-dimensional (3D) reaction-diffusion-convection system. We investigate the effects of buoyancy-driven convection in such a setting. The 3D waves traveled through horizontal layers of the iodate–arsenous acid (IAA) reaction solution containing excess of arsenous acid. The depth of the reaction solution was the examined parameter. An increase in the intensity of buoyancy-driven flow caused an increase of t...

  13. Buoyancy driven flow in a hot water tank due to standby heat loss

    DEFF Research Database (Denmark)

    Fan, Jianhua; Furbo, Simon

    2012-01-01

    show that the CFD model predicts satisfactorily water temperatures at different levels of the tank during cooling by standby heat loss. It is elucidated how the downward buoyancy driven flow along the tank wall is established by the heat loss from the tank sides and how the natural convection flow...

  14. Buoyancy-driven flow reversal phenomena in radially rotating serpentine ducts

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J.J.; Wang, W.J.; Chen, C.K.

    2000-02-01

    Convective characteristics are analyzed numerically in a rotating multipass square duct connecting with 180-deg sharp returns. Isoflux is applied to each duct wall and periodic conditions are used between the entrance and exit of a typical two-pass module. Emphasis is placed on the phenomenon of buoyancy-driven reversed flow in the serpentine duct. Predictions reveal that the radial distance from the rotational axis to the location of flow separation in the radial-outward duct decreases with increasing the Richardson number. In addition, the local buoyancy that is required to yield the radial flow reversal increases with increasing the rotation number. This buoyancy-driven reversed flow in the radial-outward duct always results in local hot spots in the cooling channels. The critical buoyancy for the initiation of flow reversal is therefore concluded for the design purpose.

  15. Turbulence-induced secondary motion in a buoyancy-driven flow in a circular pipe

    OpenAIRE

    Hallez, Yannick; Magnaudet, Jacques

    2009-01-01

    We analyze the results of a direct numerical simulation of the turbulent buoyancy-driven flow that sets in after two miscible fluids of slightly different densities have been initially superimposed in an unstable configuration in an inclined circular pipe closed at both ends. In the central region located midway between the end walls, where the flow is fully developed, the resulting mean flow is found to exhibit nonzero secondary velocity components in the tube cross section. We present a det...

  16. Experimental study of buoyancy-driven flow in a half-scale stairwell model

    Energy Technology Data Exchange (ETDEWEB)

    Zohrabian, A.S.; Mokhtarzadeh-Dehghan, M.R.; Reynolds, A.J. (Brunel Univ., Uxbridge (GB). Dept. of Mechanical Engineering); Marriott, B.S.T. (Logica EIS Ltd., London (GB))

    1989-01-01

    This paper describes an experimental study of buoyancy-driven flows of mass and energy in a half-scale model of a stairwell. Two different geometries are considered. The stairwell model forms a closed system, within which the circulation of air is maintained by the continuous operation of a heater placed in the lower floor. The rig, its instrumentation and the computerized data-logging system are described in detail. The overall features of the flow are also described. The results include the velocity and temperature distributions and the circulating volume flow. The effects of heat input rate on these parameters are also discussed. (author).

  17. Release of radon contaminants from Yucca Mountain: The role of buoyancy driven flow

    International Nuclear Information System (INIS)

    The potential for the repository heat source to promote buoyancy driven flow and thereby cause release of radon gas out of Yucca Mountain has been examined through a critical review of the theoretical and experimental studies of this process. The review indicates that steady-state buoyancy enhanced release of natural radon and other contaminant gases should not be a major concern at Yucca Mountain. Barometric pumping and wind pumping are identified as two processes that will have a potentially greater effect on surface releases of gases

  18. A Review of Some Recent Studies on Buoyancy Driven Flows in an Urban Environment

    OpenAIRE

    Bodhisatta Hajra

    2014-01-01

    This paper reviews some recent studies (after 2000) pertaining to buoyancy driven flows in nature and thier use in reducing air pollution levels in a city (city ventilation). Natural convection flows occur due to the heating and cooling of various urban surfaces (e.g., mountain slopes), leading to upslope and downslope flows. Such flows can have a significant effect on city ventilation which has been the subject of study in the recent times due to increased pollution levels in a city. A major...

  19. CO$_2$ dissolution controlled by buoyancy driven shear dispersion in a background hydrological flow

    CERN Document Server

    Unwin, H Juliette T; Woods, Andrew W

    2015-01-01

    We present an analytical and numerical study of the long-time flow which controls the dissolution of a plume of CO$_2$ following injection into an anticline structure in a deep saline aquifer of finite vertical extent. Over times of tens to thousands of years, some of the CO$_2$ will dissolve into the underlying groundwater to produce a region of relatively dense, CO$_2$ saturated water directly below the plume of CO$_2$. Continued dissolution then requires the supply of CO$_2$ unsaturated aquifer water. This may be provided by a background hydrological flow or buoyancy driven flow caused by the density contrast between the CO$_2$ saturated and unsaturated water in the aquifer. At long times, the interaction of the cross-layer diffusive mixing with the buoyancy, leads to buoyancy driven shear dispersion of the CO$_2$. With a background hydrological flow, the upstream transport of dissolved CO$_2$ by this dispersion becomes balanced by the oncoming hydrological flow so that CO$_2$ rich water can only spread a ...

  20. Design and Energy Performance of a Buoyancy Driven Exterior Shading Device for Building Application in Taiwan

    Directory of Open Access Journals (Sweden)

    Kuo-Tsang Huang

    2015-03-01

    Full Text Available Traditional dynamic shading systems are usually driven by electricity for continuously controlling the angle of blind slats to minimize the indoor solar heat gain over times. This paper proposed a novel design of buoyancy driven dynamic shading system, using only minimum amount of electricity. The energy performance and the improved thermal comfort induced by the system were simulated by EnergyPlus for a typical office space under the context of Taiwanese climate. The design processes are composed of three parts: an alterable angle of blind slats that raises the energy performance to be suitable for every orientation, the buoyancy driven transmission mechanism, and a humanized controller that ensures its convenience. The environmental friendly design aspects and control mechanisms to fulfill demands for manufacturing, assembling, maintenance and recycling, etc., were also presented as readily for building application. Besides, the effectiveness of cooling energy saving and thermal comfort enhancing were compared against the cases without exterior blinds and with traditional fixed blinds installed. The results show that the cooling energy is drastically reduced over times and the blind system is effectively enhancing the indoor thermal comfort.

  1. Modeling Diffusion and Buoyancy-Driven Convection with Application to Geological CO2 Storage

    KAUST Repository

    Allen, Rebecca

    2015-04-01

    ABSTRACT Modeling Diffusion and Buoyancy-Driven Convection with Application to Geological CO2 Storage Rebecca Allen Geological CO2 storage is an engineering feat that has been undertaken around the world for more than two decades, thus accurate modeling of flow and transport behavior is of practical importance. Diffusive and convective transport are relevant processes for buoyancy-driven convection of CO2 into underlying fluid, a scenario that has received the attention of numerous modeling studies. While most studies focus on Darcy-scale modeling of this scenario, relatively little work exists at the pore-scale. In this work, properties evaluated at the pore-scale are used to investigate the transport behavior modeled at the Darcy-scale. We compute permeability and two different forms of tortuosity, namely hydraulic and diffusive. By generating various pore ge- ometries, we find hydraulic and diffusive tortuosity can be quantitatively different in the same pore geometry by up to a factor of ten. As such, we emphasize that these tortuosities should not be used interchangeably. We find pore geometries that are characterized by anisotropic permeability can also exhibit anisotropic diffusive tortuosity. This finding has important implications for buoyancy-driven convection modeling; when representing the geological formation with an anisotropic permeabil- ity, it is more realistic to also account for an anisotropic diffusivity. By implementing a non-dimensional model that includes both a vertically and horizontally orientated 5 Rayleigh number, we interpret our findings according to the combined effect of the anisotropy from permeability and diffusive tortuosity. In particular, we observe the Rayleigh ratio may either dampen or enhance the diffusing front, and our simulation data is used to express the time of convective onset as a function of the Rayleigh ratio. Also, we implement a lattice Boltzmann model for thermal convective flows, which we treat as an analog for

  2. Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries

    CERN Document Server

    D'Angelo, Maria Veronica; Allain, Catherine; Rosen, Marta; Hulin, Jean-Pierre

    2008-01-01

    The influence of a small relative density difference on the displacement of two miscible liquids is studied experimentally in transparent 2D networks of micro channels. Both stable displacements in which the denser fluid enters at the bottom of the cell and displaces the lighter one and unstable displacements in which the lighter fluid is injected at the bottom and displaces the denser one are realized. Except at the lowest mean flow velocity U, the average $C(x,t)$ of the relative concentration satisfies a convection-dispersion equation. The dispersion coefficient is studied as function of the relative magnitude of fluid velocity and of the velocity of buoyancy driven fluid motion. A model is suggested and its applicability to previous results obtained in 3D media is discussed.

  3. Effects of buoyancy-driven flow and thermal boundary conditions on physical vapor transport

    Science.gov (United States)

    Nadarajah, Arunan; Rosenberger, Franz; Alexander, J. I. D.

    1992-01-01

    A 2D numerical model was developed in order to ascertain if reduced gravity conditions are beneficial to physical vapor transport (PVT) and to determine its tolerance limits to residual accelerations. This was solved using the PHOENICS finite-volume code. Reduction of gravitational accelerations to less than 0.1 g0 was found to be sufficient to suppress buoyancy-driven convection to an extent that diffusion was the dominant transport mode, whence a greater uniformity in the growth rate could be obtained. It is shown that a uniform temperature gradient on the ampoule walls causes the vapor to be supersaturated throughout the ampoule, potentially resulting in undesirable nucleation at the walls. A 'hump' in the wall temperature profile can be used to avoid this. The prevailing transport conditions determine the size of the hump needed.

  4. A Review of Some Recent Studies on Buoyancy Driven Flows in an Urban Environment

    Directory of Open Access Journals (Sweden)

    Bodhisatta Hajra

    2014-01-01

    Full Text Available This paper reviews some recent studies (after 2000 pertaining to buoyancy driven flows in nature and thier use in reducing air pollution levels in a city (city ventilation. Natural convection flows occur due to the heating and cooling of various urban surfaces (e.g., mountain slopes, leading to upslope and downslope flows. Such flows can have a significant effect on city ventilation which has been the subject of study in the recent times due to increased pollution levels in a city. A major portion of the research reviewed here consists of natural convection flows occurring along mountain slopes, with a few studies devoted to flows along building walls. The studies discussed here primarily include field measurements and computational fluid dynamics (CFD models. This review shows that for densely populated cities with high pollution levels, natural convection flows (mountain slope or building walls can significantly aid the dispersion of pollutants. Additional studies in this area using CFD and water channel measurements can explain the physical processes involved in such flows and help improve CFD modelling. Future research should focus on a complete understanding of the mechanisms of buoyancy flows in nature and developing design guidelines for better planning of cities.

  5. Modeling and Assessment of Buoyancy-Driven Stratified Airflow in High-Space Industrial Hall

    Institute of Scientific and Technical Information of China (English)

    WANG Han-qing; CHEN Ke; HU Jian-jun; KOU Guang-xiao; WANG Zhi-yong

    2009-01-01

    In industrial environment,heat sources often are contaminant sources and health threatening con-taminants are mainly passive,so a detailed understanding of airflow mode can assist in work environment hy-giene measurement and prevention.This paper presented a numerical investigation of stratified airflow scenario in a high-space industrial hall with validated commercial code and experimentally acquired boundary conditions.Based upon an actually undergoing engineering project,this study investigated the performance of the buoyancy-driven displacement ventilation in a large welding hall with big components manufactured.The results have demonstrated that stratified airflow sustained by thermal buoyancy provides zoning effect in terms of clean and polluted regions except minor stagnant eddy areas.The competition between negative buoyant jets from displace-ment radial diffusers and positive buoyant plume from bulk object constitutes the complex transport characteris-tics under and above stratification interface.Entrainment,downdraft and turbulent eddy motion complicate the upper mixing zone,but the exhaust outlet plays a less important role in the whole field flow.And the corre-sponding suggestions concerning computational stability and convergence,further improvements in modeling and measurements were given.

  6. Buoyancy-driven instability in a vertical cylinder: Binary fluids with Soret effect. I - General theory and stationary stability results

    Science.gov (United States)

    Hardin, G. R.; Sani, R. L.; Henry, D.; Roux, B.

    1990-01-01

    The buoyancy-driven instability of a monocomponent or binary fluid completely contained in a vertical circular cylinder is investigated, including the influence of the Soret effect for the binary mixture. The Boussinesq approximation is used, and the resulting linear stability problem is solved using a Galerkin technique. The analysis considers fluid mixtures ranging from gases to liquid metals. The flow structure is found to depend strongly on both the cylinder aspect ratio and the magnitude of the Soret effect. The predicted stability limits are shown to agree closely with experimental observations.

  7. Buoyancy-driven inflow to a relic cold core: the gas belt in radio galaxy 3C 386

    Science.gov (United States)

    Duffy, R. T.; Worrall, D. M.; Birkinshaw, M.; Kraft, R. P.

    2016-07-01

    We report measurements from an XMM-Newton observation of the low-excitation radio galaxy 3C 386. The study focusses on an X-ray-emitting gas belt, which lies between and orthogonal to the radio lobes of 3C 386 and has a mean temperature of 0.94 ± 0.05 keV, cooler than the extended group atmosphere. The gas in the belt shows temperature structure with material closer to the surrounding medium being hotter than gas closer to the host galaxy. We suggest that this gas belt involves a `buoyancy-driven inflow' of part of the group-gas atmosphere where the buoyant rise of the radio lobes through the ambient medium has directed an inflow towards the relic cold core of the group. Inverse-Compton emission from the radio lobes is detected at a level consistent with a slight suppression of the magnetic field below the equipartition value.

  8. Buoyancy-driven inflow to a relic cold core: the gas belt in radio galaxy 3C 386

    CERN Document Server

    Duffy, R T; Birkinshaw, M; Kraft, R P

    2016-01-01

    We report measurements from an XMM-Newton observation of the low-excitation radio galaxy 3C 386. The study focusses on an X-ray-emitting gas belt, which lies between and orthogonal to the radio lobes of 3C 386 and has a mean temperature of $0.94\\pm0.05$ keV, cooler than the extended group atmosphere. The gas in the belt shows temperature structure with material closer to the surrounding medium being hotter than gas closer to the host galaxy. We suggest that this gas belt involves a `buoyancy-driven inflow' of part of the group-gas atmosphere where the buoyant rise of the radio lobes through the ambient medium has directed an inflow towards the relic cold core of the group. Inverse-Compton emission from the radio lobes is detected at a level consistent with a slight suppression of the magnetic field below the equipartition value.

  9. Passive urban ventilation by combined buoyancy-driven slope flow and wall flow: Parametric CFD studies on idealized city models

    Science.gov (United States)

    Luo, Zhiwen; Li, Yuguo

    2011-10-01

    This paper reports the results of a parametric CFD study on idealized city models to investigate the potential of slope flow in ventilating a city located in a mountainous region when the background synoptic wind is absent. Examples of such a city include Tokyo in Japan, Los Angeles and Phoenix in the US, and Hong Kong. Two types of buoyancy-driven flow are considered, i.e., slope flow from the mountain slope (katabatic wind at night and anabatic wind in the daytime), and wall flow due to heated/cooled urban surfaces. The combined buoyancy-driven flow system can serve the purpose of dispersing the accumulated urban air pollutants when the background wind is weak or absent. The microscopic picture of ventilation performance within the urban structures was evaluated in terms of air change rate (ACH) and age of air. The simulation results reveal that the slope flow plays an important role in ventilating the urban area, especially in calm conditions. Katabatic flow at night is conducive to mitigating the nocturnal urban heat island. In the present parametric study, the mountain slope angle and mountain height are assumed to be constant, and the changing variables are heating/cooling intensity and building height. For a typical mountain of 500 m inclined at an angle of 20° to the horizontal level, the interactive structure is very much dependent on the ratio of heating/cooling intensity as well as building height. When the building is lower than 60 m, the slope wind dominates. When the building is as high as 100 m, the contribution from the urban wall flow cannot be ignored. It is found that katabatic wind can be very beneficial to the thermal environment as well as air quality at the pedestrian level. The air change rate for the pedestrian volume can be as high as 300 ACH.

  10. U-Pb geochronological constraints on the timing of episodic regional metamorphism and rapid high-T exhumation of the Grand Forks complex, British Columbia

    Science.gov (United States)

    Cubley, J. F.; Pattison, D. R. M.; Tinkham, D. K.; Fanning, C. M.

    2013-01-01

    The Grand Forks complex (GFC) is a fault-bounded metamorphic core complex in the southern Omineca Belt of British Columbia, Canada. It experienced prograde metamorphism ranging from upper-amphibolite to granulite facies conditions during the Mesozoic to early Tertiary compressional stage of the Cordilleran orogeny. Peak metamorphism was followed by multi-stage exhumation in the Early Eocene. This study provides U-Pb monazite and zircon constraints on the timing of metamorphic episodes in the GFC and subsequent high-T, amphibolite facies decompression in the Early Eocene. Monazite LA-ICP-MS ages from metapelitic gneisses record episodic metamorphism from the Late Jurassic to Paleocene, with peak metamorphism occurring between ~ 59 and 50 Ma. Peak metamorphism was followed by rapid, near-isothermal decompression of the GFC between ~ 52 and 50 Ma, and leucosome crystallization at ~ 50 Ma. Thermodynamic modeling of metapelites in the system MnNCKFMASHPYCe predicts that monazite was not stable at peak metamorphic conditions, consistent with the dominant population of ~ 59 Ma ages representing growth along the prograde path, most likely at subsolidus conditions. Growth of widespread high-Y monazite rims (~ 50 Ma) is predicted along suprasolidus decompression and cooling paths. Zircon SHRIMP ages from igneous bodies in the GFC and hanging wall of the bounding Kettle River fault (KRF) suggest ductile deformation related to high-T decompression of the GFC was ongoing at 51 Ma but had ceased by 50 Ma, truncated by post-kinematic granitoids. This high-T deformation predates subsequent greenschist facies extension on the overlying KRF. A pre-KRF, hanging wall ductile shear zone is constrained to ~ 59-51 Ma. It deforms 59 Ma Ladybird suite leucogranites and may be related to high-T exhumation of the core complex. Rapid, > 100 °C/Ma cooling rates are required to accommodate high-T (amphibolite facies) exhumation of the GFC at 52-50 Ma followed by low-T (greenschist facies

  11. Numerical Investigation of Heat Transfer with Thermal Radiation in an Enclosure in Case of Buoyancy Driven Flow

    Directory of Open Access Journals (Sweden)

    Christoph Hochenauer

    2014-08-01

    Full Text Available The purpose of this paper is to investigate state of the art approaches and their accuracy to compute heat transfer including radiation inside a closed cavity whereas buoyancy is the only driving force. This research is the first step of an all-embracing study dealing with underhood airflow and thermal management of vehicles. Computational fluid dynamic (CFD simulation results of buoyancy driven flow inside a simplified engine compartment are compared to experimentally gained values. The test rig imitates idle condition without any working fan. Thus, the airflow is only driven by natural convection. A conventional method used for these applications is to compute the convective heat transfer coefficient and air temperature using CFD and calculate the wall temperature separately by performing a thermal analysis. The final solution results from coupling two different software tools. In this paper thermal conditions inside the enclosure are computed by the use of CFD only. The impact of the turbulence model as well as the results of various radiation models are analyzed and compared to the experimental data.

  12. The buoyancy-driven motion of a single skirted bubble or drop rising through a viscous liquid

    Science.gov (United States)

    Ohta, Mitsuhiro; Sussman, Mark

    2012-11-01

    The buoyancy-driven motion of a single skirted bubble or drop rising through a viscous liquid is computationally explored by way of 3d-axisymmetric computations. The Navier-Stokes equations for incompressible two-fluid flow are solved numerically in which the coupled level-set and volume-of-fluid method is used to simulate the deforming bubble/drop boundary and the interface jump conditions on the deforming boundary are enforced through a sharp interface numerical treatment. Dynamic, block structured adaptive grid refinement is employed in order to sufficiently resolve the thin skirts. Results on the sensitivity of the thickness of trailing bubble/drop skirts to the density ratio and viscosity ratio are reported. It is shown that both the density ratio (not the density difference) and the viscosity ratio effect the skirt thickness. Previous theory for predicting skirt thickness can be refined as a result of our calculations. It is also discovered that the formation of thin skirts for bubbles and drops have little effect on the rise velocity. In other words, the measured Re number for cases without skirt formation have almost the same values for Re as cases with a thin skirt.

  13. Evidence for Rapid Post-Pliocene Exhumation of the Santa Monica Mountains, California, from Apatite (U-Th)/He Thermochronometry

    Science.gov (United States)

    Niemi, N. A.; Clark, M. K.; Yakovlev, P. V.

    2015-12-01

    Potential losses related to large earthquakes on blind or previously unrecognized thrust faults is of significant concern to southern California, where numerous individual mountain ranges are underlain by active faults. Some of the most hazardous thrust fault systems in Southern California are associated with high-slip-rate faults in the northern portion of the western Transverse Ranges, while the southern region is generally considered to be less seismically active. Determining slip rates on faults bounding the Santa Monica Mountains has been challenging, in part because many of the faults that underlie the range have submarine surface traces. Existing geologic studies predict that these faults slip relatively slowly; however, recent GPS models predict a band of relatively fast contraction on faults that lie beneath the Santa Monica Mountains (Marshall et al., 2013). These geodetic models suggest unrecognized hazard associated with shortening and vertical uplift of this range. Late Cenozoic strata in the central Santa Monica Mountains are of sufficient thickness to bury Cretaceous and Paleocene strata above the closure temperature for apatite (U-Th)/He thermochronometry (~70°C). As a result, these older rocks, now exposed in the southern Santa Monica Mountains, may record exhumation associated with fault slip and associated structural deformation of the range. Preliminary apatite (U-Th)/He ages near Las Flores Canyon span from 3.5 to 6.5 Ma, and are the youngest apatite (U-Th)/He ages we are aware of in southern California outside of the transpressional San Andreas system. When plotted as depth beneath the base of the marine Modelo Formation, an inflection in age/depth gradient at 4 Ma is inferred to reflect the onset of fault motion and is consistent with the late Miocene age of the Modelo Formation. Based on average geothermal gradients for the Ventura and Los Angeles basins and an assumed thrust fault dip of 20°, observed apparent exhumation rates are

  14. Experimental study on buoyancy-driven exchange flows through breaches of a tokamak vacuum vessel in a fusion reactor under the loss-of-vacuum-event conditions

    Energy Technology Data Exchange (ETDEWEB)

    Takase, Kazuyuki; Tomoaki, Kunugi; Ogawa, Masurou; Seki, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)

    1997-02-01

    As one of thermofluid safety studies in the International Thermonuclear Experimental Reactor, buoyancy-driven exchange flow behavior through breaches of a vacuum vessel (VV) has been investigated quantitatively by using a preliminary loss-of-vacuum-event (LOVA) apparatus that simulated the tokamak VV of a fusion reactor with a small-scaled model. To carry out the present experiments under the atmospheric pressure condition, helium gas and air were provided as the working fluids. The inside of the VV was initially filled with helium gas and the outside was atmosphere. The breaches on the VV under the LOVA condition were simulated by opening six simulated breaches to which were set the different positions on the VV. When the buoyancy-driven exchange flow through the breach occurred, helium gas went out from the inside of the VV through the breach to the outside and air flowed into the inside of the VV through the breach from the outside. The exchange rate in the VV between helium gas and air was calculated from the measured weight change of the VV with time since the experiment has started. experimental parameters were breach position, breach number, breach length, breach size, and breach combination. The present study clarifies that the relation between the exchange rate and the breach position of the VV depended on the magnitude of the potential energy from the ground level to the breach position, and then, the exchange rate decreased as the breach length increased and as the breach size decreased.

  15. Research on buoyancy driven underwater glider attitude adjusting machine%浮力驱动式水下滑翔机姿态调节机构研究

    Institute of Scientific and Technical Information of China (English)

    邬明; 孙善春

    2012-01-01

    浮力驱动式水下滑翔机对我国海洋勘探和国防建设有着重要的应用前景.本文介绍了水下滑翔机的工作机理,对某一滑翔机,重点设计了实现姿态调整的横滚控制组件和俯仰控制组件,同时提出总体布局的原则,并给出了滑翔机总体结构布局方案.对所设计的滑翔机的总体衡重参数和流体动力参数进行了计算,初步验证了总体设计方案的可行性,可以满足设计指标要求.%Buoyancy driven underwater glider has important application prospects in ocean exploitation and national defense. The article introduces mechanism of buoyancy driven underwater glider, according to one glider,specifically design the discreteness of roll and pitching to achieve attitude control, and put the structure position of the glider. Ultimately,computes the weight and hydrokinetic parameters of the glider,preliminary verify feasibility of total design scheme,is meet design requirement on most of design target.

  16. Numerical investigations of buoyancy-driven natural ventilation in a simple atrium building and its effect on the thermal comfort conditions

    International Nuclear Information System (INIS)

    In the present study use of solar-assisted buoyancy-driven natural ventilation in a simple atrium building is explored numerically with particular emphasis on the thermal comfort conditions in the building. Initially various geometric configurations of the atrium space were considered in order to investigate airflows and temperature distributions in the building using a validated computational fluid dynamics (CFD) model. The Reynolds Averaged Navier–Stokes (RANS) modelling approach with the SST-k–ω turbulence model and the Discrete Transfer Radiation Model (DTRM) was used for the investigations. The steady-state governing equations were solved using a commercial CFD solver FLUENT©. From the numerical results obtained, it was noted that an atrium space integrated with a solar chimney would be a relatively better option to be used in an atrium building. In the geometry selected, the performance of the building in response to various changes in design parameters was investigated. The produced airflows and temperature distributions were then used to evaluate indoor thermal comfort conditions in terms of the thermal comfort indices, i.e. the well-known predicted mean vote (PMV) index, its modifications especially for natural ventilation, predicted percent dissatisfied (PPD) index and Percent dissatisfied (PD) factor due to draft. It was found that the thermal conditions in the occupied areas of the building developed as a result of the use of solar-assisted buoyancy-driven ventilation for the particular values of the design parameters selected are mostly in the comfortable zone. Finally, it is demonstrated that the proposed methodology leads to reliable thermal comfort predictions, while the effect of various design variables on the performance of the building is easily recognized. - Highlights: ► Numerical investigations were carried for the use of buoyancy-driven displacement ventilation in a simple atrium building. ► Effect of various atrium configurations

  17. A computational model for the rise and dispersion of wind-blown, buoyancy-driven plumes—II. Linearly stratified atmosphere

    Science.gov (United States)

    Zhang, Xiaoming; Ghoniem, Ahmed F.

    A multi-dimensional computational model of wind-blown, buoyancy-driven flows is applied to study the effect of atmospheric stratification on the rise and dispersion of plumes. The model utilizes Lagrangian transport elements, distributed in the plane of the plume cross section normal to the wind direction, to caoture the evolution of the vorticity and density field, and another set of elements to model the dynamics in the atmosphere surrounding the plume. Solutions are obtained for a case in which atmospheric density changes linearly with height. Computational results show that, similar to the case of a neutrally stratified atmosphere, the plume acquires a kidney-shaped cross section which persists for a long distance downstream the source and may bifurcate into separate and distinct lumps. Baroclinic vortivity generated both along the plume boundary and in the surroundings is used to explain the origin of the distortion experienced by the plume and the inhibiting effect of a stratified atmosphere, respectively. The vorticity within the plume cross section forms two large-scale coherent eddies which are responsible for the plume motion and the entrainment. Prior to reaching the equilibrium height, the computed plume trajectory is found to follow the two-thirds law, when extended to include the initial plume size, reasonably well. Entrainment and added mass coefficients equal to 0.49 and 0.7 respectively, are obtained from the numerical results over a wide range of the buoyancy ratio, defined as the ratio between the plume buoyancy and the degree of background stratification. In the case of strong stratification, the plume trajectory shows weak, fast decaying oscillations around the equilibrium height.

  18. Buoyancy driven rotating boundary currents

    CERN Document Server

    Yecko, P A

    1997-01-01

    The structure of boundary currents formed from intermediately dense water introduced into a rotating, stably stratified, two-layer environment is investigated in a series of laboratory experiments, performed for Froude numbers ranging from 0.01 to 1. The thickness and streamwise velocity profiles in quasi-steady currents are measured using a pH activated tracer (thymol blue) and found to compare favorably to simplified analytic solutions and numerical models. Currents flowing along sloping boundaries in a stratified background exhibit robust stability at all experimental Froude numbers. Such stability is in sharp contrast to the unequivocal instability of such currents flowing against vertical boundaries, or of currents flowing along slopes in a uniform background. The presence of a variety of wave mechanisms in the ambient medium might account for the slower and wider observed structures and the stability of the currents, by effecting the damping of disturbances through wave radiation.

  19. Buoyancy-driven Magnetohydrodynamic Waves

    Science.gov (United States)

    Hague, A.; Erdélyi, R.

    2016-09-01

    Turbulent motions close to the visible solar surface may generate low-frequency internal gravity waves (IGWs) that propagate through the lower solar atmosphere. Magnetic activity is ubiquitous throughout the solar atmosphere, so it is expected that the behavior of IGWs is to be affected. In this article we investigate the role of an equilibrium magnetic field on propagating and standing buoyancy oscillations in a gravitationally stratified medium. We assume that this background magnetic field is parallel to the direction of gravitational stratification. It is known that when the equilibrium magnetic field is weak and the background is isothermal, the frequencies of standing IGWs are sensitive to the presence of magnetism. Here, we generalize this result to the case of a slowly varying temperature. To do this, we make use of the Boussinesq approximation. A comparison between the hydrodynamic and magnetohydrodynamic cases allows us to deduce the effects due to a magnetic field. It is shown that the frequency of IGWs may depart significantly from the Brunt-Väisälä frequency, even for a weak magnetic field. The mathematical techniques applied here give a clearer picture of the wave mode identification, which has previously been misinterpreted. An observational test is urged to validate the theoretical findings.

  20. Testing models of orogen exhumation using zircon (U-Th)/He thermochronology: Insight from the Ligurian Alps, Northern Italy

    Science.gov (United States)

    Maino, Matteo; Dallagiovanna, Giorgio; Dobson, Katherine J.; Gaggero, Laura; Persano, Cristina; Seno, Silvio; Stuart, Finlay M.

    2012-08-01

    Testing models of orogen exhumation requires precise constraint of the time-temperature paths of the exhumed rocks. The zircon (U-Th)/He (ZHe) thermochronometer has a closure temperature of ~ 140-210 °C, and can provide temporal constraints on the exhumation history of rocks through a thermal range which crucially corresponds the onset of brittle behaviour of an exhuming orogen. We performed ZHe analyses to test the existing contradictory models for the exhumation of the Ligurian Alps. The ZHe ages indicate a very rapid (1.3-6.8 mm/yr) and southward migrating exhumation of the orogen between ~ 32 and 25 Ma. These high exhumation rates are unique within the Alpine belt and cannot be reconciled with existing geodynamic models of the evolution of the Ligurian Alps. We propose a model of tectonic denudation via detachment accomplished in the shallowest crust (< 5 km) as a result of the last orogenic phase of extension.

  1. Two-stage exhumation of subducted Saxothuringian continental crust records underplating in the subduction channel and collisional forced folding (Krkonoše-Jizera Mts., Bohemian Massif)

    Science.gov (United States)

    Jeřábek, Petr; Konopásek, Jiří; Žáčková, Eliška

    2016-08-01

    The Krkonoše-Jizera Massif in the northern part of the Variscan Bohemian Massif provides insight into the exhumation mechanisms for subducted continental crust. The studied region exposes a relatively large portion of a flat-lying subduction-related complex that extends approximately 50 km away from the paleosuture. wide extent of HP-LT metamorphism has been confirmed by new P-T estimates indicating temperatures of 400-450 °C at 14-16 kbar and 450-520 °C at 14-18 kbar for the easternmost and westernmost parts of the studied area, respectively. A detailed study of metamorphic assemblages associated with individual deformation fabrics together with analysis of quartz deformation microstructures and textures allowed characterisation of the observed deformation structures in terms of their subduction-exhumation memory. An integration of the lithostratigraphic, metamorphic and structural data documents a subduction of distal and proximal parts of the Saxothuringian passive margin to high-pressure conditions and their subsequent exhumation during two distinct stages. The initial stage of exhumation has an adiabatic character interpreted as the buoyancy driven return of continental material from the subduction channel resulting in underplating and progressive nappe stacking at the base of the Teplá-Barrandian upper plate. With the transition from continental subduction to continental collision during later stages of the convergence, the underplated high-pressure rocks were further exhumed due to shortening in the accretionary wedge. This shortening is associated with the formation of large-scale recumbent forced folds extending across the entire studied area.

  2. Energy Spectrum of Buoyancy-Driven Turbulence

    OpenAIRE

    Kumar, Abhishek; Chatterjee, Anando G.; Verma, Mahendra K.

    2014-01-01

    Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux $\\Pi_u$, we demonstrate that for stably stratified flows, the kinetic energy spectrum $E_u(k) \\sim k^{-11/5}$, the entropy spectrum $E_\\theta(k) \\sim k^{-7/5}$, and $\\Pi_u(k) \\sim k^{-4/5}$, consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence $E_u(k)$ follo...

  3. Nonlinear Control of a Buoyancy Driven Airship

    OpenAIRE

    Wu, Xiaotao,; Moog, Claude; Marquez Martinez, L.

    2009-01-01

    The control of a new kind of airship is presented. By restricting its flight to a vertical plane, the athematical model is reduced. The simplified model is proved to be minimum phase, and a nonlinear controller based on inputoutput linearization is designed. Since the performance of the controller is significantly impacted by the choice of parameters, simulations of three different pole placement strategies are presented. The nonlinear controller shows better performances than a linear LQR co...

  4. Energy spectrum of buoyancy-driven turbulence

    KAUST Repository

    Kumar, Abhishek

    2014-08-25

    Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux Πu, we demonstrate that, for stably stratified flows, the kinetic energy spectrum Eu(k)∼k-11/5, the potential energy spectrum Eθ(k)∼k-7/5, and Πu(k)∼k-4/5 are consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence Eu(k) follows Kolmogorov\\'s spectrum with a constant energy flux. For Rayleigh-Bénard convection, we show that the energy supply rate by buoyancy is positive, which leads to an increasing Πu(k) with k, thus ruling out Bolgiano-Obukhov scaling for the convective turbulence. Our numerical results show that convective turbulence for unit Prandt number exhibits a constant Πu(k) and Eu(k)∼k-5/3 for a narrow band of wave numbers. © 2014 American Physical Society.

  5. Late Cenozoic exhumation of New Zealand: inversion from bedrock thermochronological ages

    Science.gov (United States)

    Jiao, Ruohong; Herman, Frédéric; Seward, Diane

    2016-04-01

    In the SW Pacific, the present subaerial land area of New Zealand straddles the boundary between the Australian and Pacific Plates. This margin has been converging since the mid-Eocene-late Oligocene, leading to a period of widespread crustal deformation and exhumation. During the past decades, the exhumation of the New Zealand basement has been the basis of many thermochronological studies, resulting in a large number of data from the Palaeozoic and Mesozoic bedrocks. We compiled the cooling ages from multiple thermochronological systems (i.e. apatite and zircon (U-Th)/He, apatite and zircon fission-track, K-feldspar, muscovite, biotite and hornblende 40Ar/39Ar or K-Ar) that yielded cooling events younger than 25 Ma, and formally inverted this data set to estimate the large-scale temporal and spatial variations in the exhumation rates of New Zealand during the late Cenozoic. The exhumation results show good agreement with the predicted off-shore sedimentation rates, while the thermal model used in the inversion is in part constrained by the present-day observed surface heat flow. The modelling results indicate crustal exhumation from the earliest Miocene (just prior to 20 Ma). But from ~10 Ma, a moderate acceleration of exhumation is observed at most sites, coincident with an important change in the orientation of the Pacific motion relative to the Australian Plate. Since the Quaternary, rapid exhumation has occurred in the Southern Alps along the west coast of South Island, with the highest rates in the central part of range. In this region, our estimates of the million-year-scale exhumation rates are in general coincidence with those previously estimated over shorter (i.e. 0.1 Ma and 10 ka) time scales, as well as with the contemporary rock uplift rates derived from GPS data, confirming exhumational steady-state in the orogeny. In contrast in eastern North Island, the predicted Quaternary exhumation rates are much lower than the recent rock uplift rates measured

  6. Exhumation history of the Serra do Mar, southeast Brazil

    Science.gov (United States)

    Carina Siqueira-Ribeiro, Marli; Hackspacher, Peter; Stuart, Finlay M.

    2016-04-01

    The Serra do Mar (SM) mountain range located along the southeast Brazilian continental margin is characterized by a low-lying coastal plateau separated from the elevated inland plateau by a steep escarpment. This morphology is a result of reactivation of Precambrian shear zones since the break-up of the Western Gondwana and opening of the South Atlantic Ocean in Early Cretaceous (1). Previous Thermochronological data from southeast Brazilian highlands (2,3), indicates that the landscape evolution is associated with several distinct exhumation events. In order to clarify the intensity and duration of the post-break up tectonic processes that shaped the SM we have undertaken a low temperature thermochronology study of crystalline basement, from the plateaus and escarpments situated between south of Rio de Janeiro and São Paulo state. Apatite fission track (AFT) and (U-Th/He) and (AHe) dating has been combined with geologic information to generate precise thermal histories and make initial attempts to quantify the amount of exhumation. AFT ages range from 145 to 53 Ma whereas preliminary AHe ages range from 75 to 37 Ma. Forward modeling using QTQt confirms Late Cretaceous-Paleogene cooling identified earlier (4,5) and identifies a distinct cooling phase in Neogene, between 30 and 10 Ma. Neogene cooling rapid caused exhumation of rocks 1 km through of the crust mainly in south portion of the SM in Rio de Janeiro state. (1) Almeida, 1976. An. Academia Bras de Cien 48 (suppl.), 15-(2) (2) Hackspacher et al. 2004. Gondwana Research,vol.2, 91-101. (3) Hiruma et al. 2010. Gondwana Research,18,674-687. (4) Siqueira-Ribeiro et al. 2011. Revista Bras. de Geomorfologia, 13, 3-14 (5) Cogné et al. 2012. Journal Geophysical Research, vol.117,1-16.

  7. Late-Quaternary exhumation of Namche Barwa constrained using low-temperature multi-OSL-thermochronometry

    Science.gov (United States)

    King, Georgina; Herman, Frederic

    2016-04-01

    The influence of climate on tectonic processes remains a controversial concept. Exhumation rates of >5 mm/yr make Namche Barwa, Tibet, one of the most rapidly exhuming places on earth, and two main hypotheses have developed to explain the very high rates of exhumation there. The tectonic aneurysm model (Zeitler et al., 2001) proposes that crustal weakening coupled with extremely active surface processes causes a spatial stationarity of exhumation. Alternatively, a northward plunging antiform that is progressively migrating north-eastward (Seward and Burg, 2008) may explain the concentration of extremely low cooling ages and rapid exhumation that characterise the Namche Barwa massif. Here we use multi-OSL-thermochronometry of feldspar, which comprises a series of different systems with closure temperatures ranging from 30 to 70 C, to quantify spatial and temporal changes in exhumation rates. We have applied this new technique to a suite of samples from the Namche Barwa massif and inverting our data enables us to precisely resolve cooling histories over 0.1 Ma timescales. Our data indicate propagation of a knick-point along the Parlung river, which can be explained by progressive north-eastward migration of a northward plunging antiform. We suggest that river incision does not therefore feedback onto tectonics, as proposed by the aneurysm model. Zeitler, P.K., Meltzer, A.S., Koons, P.O., et al., 2001. Erosion, Himalayan Geodynamics, and the Geomorphology of Metamorphism. GSA Today 11, 4-9 Seward, D., Burg, J-P., 2008. Growth of the Namche Barwa Syntaxis and associated evolution of the Tsangpo Gorge: Constraints from structural and thermochronological data. Tectonophysics 451, 282-289.

  8. Late Cretaceous and Cenozoic exhumation history of the Malay Peninsula

    Science.gov (United States)

    François, Thomas; Daanen, Twan; Matenco, Liviu; Willingshofer, Ernst; van der Wal, Jorien

    2015-04-01

    The evolution of Peninsular Malaysia up to the collisional period in the Triassic is well described but the evolution since the collision between Indochina and the Sukhothai Arc in Triassic times is less well described in the literature. The processes affecting Peninsular Malaysia during the Jurassic up to current day times have to explain the emplacement multiple intrusions (the Stong Complex, and the Kemahang granite), the Jurassic/Cretaceous onland basins, the Cenozoic offshore basins, and the asymmetric extension, which caused the exhumation of Taku Schists dome. The orogenic period in Permo-Triassic times, which also formed the Bentong-Raub suture zone, resulted in thickening of the continental crust of current day Peninsular Malaysia due to the collision of the Indochina continental block and the Sukhothai Arc, and is related to the subduction of oceanic crust once present between these continental blocks. The Jurassic/Cretaceous is a period of extension, resulting in the onland Jurassic/Cretaceous basins, synchronous melting of the crust, resulting in the emplacement Stong Complex and the Kemahang granite and thinning of the continental crust on the scale of the Peninsular, followed by uplift of the Peninsular. Different models can explain these observations: continental root removal, oceanic slab detachment, or slab delamination. These models all describe the melting of the lower crust due to asthenospheric upwelling, resulting in uplift and subsequent extension either due to mantle convective movements or gravitational instabilities related to uplift. The Cenozoic period is dominated by extension and rapid exhumation in the area as documented by low temperature thermocrological ages The extension in this period is most likely related to the subduction, which resumed at 45 Ma, of the Australian plate beneath the Eurasian plate after it terminated in Cretaceous times due to the collision of an Australian microcontinental fragment with the Sunda margin in the

  9. Permeability measurements and precipitation sealing of basalt in an ancient exhumed subduction-zone fault

    OpenAIRE

    Kato, Aitaro; Sakaguchi, Arito; Yoshida, Shingo; Mochizuki, Hiromine; Kaneda, Yoshiyuki

    2003-01-01

    We conducted permeability measurements of basalt sampled from an exhumed ancient fault zone in the Cretaceous Shimanto accretionary complex in Japan, in order to investigate permeability structure and evolution following shear failure. Permeability showed a strong reduction with increase in the effective confining pressure and temperature. Rapid sealing at elevated temperatures was observed during hold experiments following shear failure. The results indicate that the permeability of a subduc...

  10. Slow exhumation of UHP terranes: Titanite and rutile ages of the Western Gneiss Region, Norway

    Science.gov (United States)

    Kylander-Clark, A. R. C.; Hacker, B. R.; Mattinson, J. M.

    2008-08-01

    U-Pb ages of titanite and rutile were obtained from the central Western Gneiss Region, Norway, to assess the style and timing of exhumation and cooling of the Western Gneiss UHP terrane. Approximately half of the titanite ages are concordant, the majority of which yield a limited age range from 393 to 390 Ma. The other titanite data are discordant, and define discordia arrays with upper intercept ages of either ˜ 938 Ma or ˜ 1.6 Ga, and a lower intercept of ˜ 389 Ma. Concordant rutile analyses range from 385 to 392 Ma. Both titanite and rutile ages young WNW toward the core of the orogen and are ˜ 4 Ma older than 40Ar/ 39Ar muscovite ages, corresponding to a cooling rate of ˜ 90 °C/Ma. A well-defined boundary between concordant and discordant titanite ages, in combination with the WNW-increasing P- T gradient and the similarity between muscovite cooling ages in the east and eclogite ages in the west, suggests that the WGR remained coherent throughout its exhumation history, and was progressively unroofed from east to west. A 390.2 ± 0.8 Ma titanite in the Sørøyane UHP domain indicates that exhumation occurred at a vertical rate of ˜ 7 mm/yr for ˜ 12 Ma. These rates are slower than estimates from smaller UHP terranes, but similar to other large UHP terranes, suggesting that there may be fundamental differences in the mechanisms controlling the evolution of large UHP terranes that undergo protracted subduction and exhumation, and smaller UHP terranes that undergo rapid subduction and exhumation.

  11. CENOZOIC EXHUMATION OF THE ANTIOQUEÑO PLATEAU, NORTHERN ANDES, COLOMBIA, FROM APATITE LOW-TEMPERATURE THERMOCHRONOLOGY

    Science.gov (United States)

    Restrepo-Moreno, S. A.; Foster, D. A.; O'Sullivan, P. B.; Donelick, R.; Stockli, D. F.

    2009-12-01

    The Antioqueño plateau (AP), in the northernmost Cordillera Central, Colombia, is the most extensive and best preserved relict surface in the Northern Andes. Apatite (U-Th)/He (AHe) and fission track (AFT) results from twenty two samples, collected from paleocrustal depths along two vertical profiles in canyons dissecting the AP, constrain Cenozoic erosional exhumation of this segment of the Andean range. The two profiles exhibit excellent reproducibility of AHe and AFT data. Helium ages increase with elevation from ~22-49 Ma. A marked inflection point in the AHe age-elevation plots at 25 Ma defines the bottom of the post-Oligocene He partial retention zone (PRZ). Virtually invariant ages at ~25 Ma record onset of rapid exhumation in the AP. A more subtle slope change in the PRZ at ~43 Ma is interpreted as a minor exhumation pulse. AFT better defines timing and intensity of Eocene exhumation. AFT ages for both profiles vary from ~30-49 Ma and are consistently older than AHe ages. AFT data display invariant ages (±2σ) between 1500-2400 m elevations while confined track length data exhibit uni-modal distributions with a mean track length of ~14.2 μm. Both facts indicate rapid cooling. This is further supported by virtually concordant AFT and AHe ages for both profiles between 1500 to 2200 m implying that rocks were exhumed from temperatures >120°C to below AHe closure temperature 60°C. Assuming a geothermal gradient of ~25°C/km this corresponds to exhumation rates in the order of 0.5 mm/y, comparable in intensity to the Miocene pulse defined by AHe. Integrated thermal modeling show an episode of rapid cooling at ~43-49 Ma. AFT profiles show an apparent inflection point at ~1400 m, which defines the upper boundary of an apatite partial annealing zone (PAZ) exhumed during the 43-49 Ma cooling event. The position of the PAZ and PRZ relative to the present erosional surface point to average erosion rates of ~0.03 mm/yr, which constitute very low denudation rates

  12. Cretaceous Exhumation of the North American Cordillera Measured through Mineral Multi-Dating: Insights into Basin Filling Models and Orogenic Architecture

    Science.gov (United States)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.; Gehrels, G. E.; Thomson, S. N.

    2015-12-01

    Apatite fission track (AFT) thermochronology is an effective thermochronometer to measure source exhumation in the North American Cordillera, western U.S.A. We use a combination of thermochronology and geochronology to measure lag times, i.e., the difference in time between the cooling and depositional ages of a mineral crystal. These lag-time measurements using source exhumation ages, measured with AFT thermochronology, and depositional ages, measured with biostratigraphy and detrital zircon U-Pb geochronology, indicate constant to decreasing lag times of 0-5 m.y. throughout the Cretaceous. These lag times are consistent with rapid exhumation rates of ~0.9->1 km/m.y. One pitfall of using detrital thermochronology to measure source exhumation is assuring that the apatite crystals are exhumed apatites and not volcanic apatites introduced into the system from the volcanic arc. To do this we use U-Pb geochronology to remove samples contaminated with young arc derived apatites and keep those with old exhumed apatites. Five of the seven detrital AFT samples were significantly contaminated with young volcanic apatites, showing that U-Pb geochronology should be a routine step in measuring lag times. Our findings demonstrate that coarse-grained foreland basin deposits in the Cretaceous Western Interior, in both the proximal and distal settings, were deposited during times of active tectonism and exhumation and that sediments are not stored in wedge-top and proximal foredeep settings for long periods of time, i.e. >5 m.y., and then subsequently reworked distally. Exhumation rates of ~0.9->1 km/m.y. are not sustainable over the entire orogenic belt for the duration of the Sevier orogeny, indicated by the lack of deep-crustal material exhumed in the North American Cordillera. High exhumation rates were likely concentrated over the eastward-propagating Sevier fold-thrust belt, whereas the Nevadaplano and hinterland experienced much slower rates of exhumation. This variation in

  13. Subduction and exhumation of continental crust: insights from laboratory models

    Science.gov (United States)

    Bialas, Robert W.; Funiciello, Francesca; Faccenna, Claudio

    2011-01-01

    When slivers of continental crust and sediment overlying oceanic lithosphere enter a subduction zone, they may be scraped off at shallow levels, subducted to depths of up to 100-200 km and then exhumed as high pressure (HP) and ultra-high pressure (UHP) rocks, or subducted and recycled in the mantle. To investigate the factors that influence the behaviour of subducting slivers of continental material, we use 3-D dynamically consistent laboratory models. A laboratory analogue of a slab-upper mantle system is set up with two linearly viscous layers of silicone putty and glucose syrup in a tank. A sliver of continental material, also composed of silicone putty, overlies the subducting lithosphere, separated by a syrup detachment. The density of the sliver, viscosity of the detachment, geometry of the subducting system (attached plate versus free ridge) and dimensions of the sliver are varied in 34 experiments. By varying the density of the sliver and viscosity of the detachment, we can reproduce a range of sliver behaviour, including subduction, subduction and exhumation from various depths and offscraping. Sliver subduction and exhumation requires sufficient sliver buoyancy and a detachment that is strong enough to hold the sliver during initial subduction, but weak enough to allow adequate sliver displacement or detachment for exhumation. Changes to the system geometry alter the slab dip, subduction velocity, pattern of mantle flow and amount of rollback. Shallower slab dips with more trench rollback produce a mantle flow pattern that aids exhumation. Steeper slab dips allow more buoyancy force to be directed in the up-dip direction of the plane of the plate, and aide exhumation of subducted slivers. Slower subduction can also aide exhumation, but if slab dip is too steep or subduction too slow, the sliver will subduct to only shallow levels and not exhume. Smaller slivers are most easily subducted and exhumed and influenced by the mantle flow.

  14. Thermochronologic evidence for Miocene mid-crustal tectonic exhumation of the Huachuca Mountains, southeast Arizona

    Science.gov (United States)

    King, C. C.; Orme, D. A.; Biswas, A.; Reiners, P. W.

    2011-12-01

    Zircon double dating of detrital grains from the northward flowing upper San Pedro river valley at Murray Springs in southeastern Arizona yields abundant zircons with variable U/Pb crystallization ages of ~70-1400 Ma, but a restricted range of (U-Th)/He cooling ages of ~18-25 Ma. This combination of diverse formation ages but uniform mid-Miocene cooling ages is characteristic of zircons from the core complexes and deeply exhumed Santa Catalina, Rincon, and Pinaleno Mountains, which experienced tectonic exhumation from mid-crustal depths during mid-Miocene extension. But all these sources are far downstream or outside the watershed of the upper San Pedro valley. To trace the source of these detrital grains and understand the implications for regional tectonics, we also measured U/Pb and (U-Th)/He dates of zircons from the Tombstone Hills and Huachuca Mountains, proximal to the Murray Springs site. Magmatic rocks in the Tombstone Hills yielded U/Pb dates of 76-83 Ma and zircon He ages of 53-60 Ma. In contrast, crystalline basement of the Huachucas yields Cretaceous through 1.5-Ga U/Pb ages and zircon He ages of 17-25 Ma, with most between 21-22 Ma. These data require that a large region of the Huachucas contains rocks that cooled rapidly below temperatures of at least 180 oC in the mid-Miocene. Assuming typical geothermal gradients of 20-30 oC, this requires exhumation of at least 7-9 km of crust, likely within 1-2 Myr. While it is possible that erosion contributed, it is more likely that denudation was accommodated by deep tectonic exhumation. Faults are observed on the basin-bounding east-side of the Huachucas, but most are inferred to accommodate Laramide-age thrusting, and the normal faults have been interpreted as high-angle and unlikely to cause significant tectonic exhumation. Our new data suggest that a large part of the presently exposed Huachucas was exhumed from depths at least as great as ~7-9 km, requiring a considerable revision of structural

  15. The effect of mechanical stirring on buoyancy-driven circulations

    OpenAIRE

    Tailleux, Remi; Rouleau, Lucie

    2009-01-01

    The theoretical analysis of the energetics of mechanically-stirred horizontal convection for a Boussinesq fluid yields the formula: G(APE) = \\gamma_{mixing} G(KE) + (1+\\gamma_{mixing}) W_{r,laminar} where G(APE) and G(KE) are the work rate done by the buoyancy and mechanical forcing respectively, \\gamma_{mixing} is the mixing efficiency, and W_{r,laminar} is the background rate of increase in gravitational potential energy due to molecular diffusion. The formula shows that mechanical stirring...

  16. Modelling and Control of a Complex Buoyancy-Driven Airship

    OpenAIRE

    Wu, Xiaotao,; Moog, Claude; Márquez-Martínez, Luis Alejandro; Hu, Yueming

    2010-01-01

    The general model for a new generation airship is introduced from the model of an elementary mechanical system which embodies the core of the problem to more complex. It is shown that the basic properties of a suitable two degree of freedom mechanical system are instrumental for the analysis and synthesis of advanced airships. It is shown that the control of the airship mechanical system yields suitable approximations for the control of the airship subject to aerodynamic forces.

  17. Buoyancy-driven flow excursions in fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D.

    1995-12-31

    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating moderator downward through channels in cylindrical fuel tubes. Powers were limited to prevent a flow excursion from occurring in one or more of these parallel channels. During full-power operation, limits prevented a boiling flow excursion from taking place. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increases beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of historical levels.

  18. Flow anisotropy in rotating buoyancy-driven turbulence

    Science.gov (United States)

    Rajaei, Hadi; Joshi, Pranav; Kunnen, Rudie P. J.; Clercx, Herman J. H.

    2016-08-01

    We report a combined experimental-numerical study of the effects of background rotation on large- and small-scale isotropy in rotating Rayleigh-Bénard convection (RBC) from both Eulerian and Lagrangian points of view. Three-dimensional particle-tracking velocimetry (3D-PTV) and direct numerical simulations (DNS) are employed at three different heights within the cylindrical cell. The Lagrangian velocity fluctuation and second-order Eulerian structure function are utilized to evaluate the large-scale isotropy for different rotation rates. Furthermore, we examine the experimental measurements of the Lagrangian acceleration of neutrally buoyant particles and the second-order Eulerian structure function to evaluate the small-scale isotropy as a function of rotation rate. It is found that background rotation enhances large-scale anisotropy at the cell center and close to the top plate, while decreases it at intermediate height. The large-scale anisotropy, induced by rotation, has negligible effect on the small scales at the cell center, whereas the small scales remain anisotropic close to the top plate.

  19. Buoyancy-driven flow excursions in fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.E.; Paul, P.K.; Menna, J.D. [Westinghouse Savannah River Company, Aiken, SC (United States)

    1995-09-01

    A power limit criterion was developed for a postulated Loss of Pumping Accident (LOPA) in one of the recently shut down heavy water production reactors at the Savannah River Site. These reactors were cooled by recirculating heavy water moderator downward through channels in cylindrical fuel tubes. Powers were limited to safeguard against a flow excursion in one of more of these parallel channels. During-full-power operation, limits safeguarded against a boiling flow excursion. At low flow rates, during the addition of emergency cooling water, buoyant forces reverse the flow in one of the coolant channels before boiling occurs. As power increased beyond the point of flow reversal, the maximum wall temperature approaches the fluid saturation temperature, and a thermal excursion occurs. The power limit criterion for low flow rates was the onset of flow reversal. To determine conditions for flow reversal, tests were performed in a mock-up of a fuel assembly that contained two electrically heated concentric tubes surrounded by three flow channels. These tests were modeled using a finite difference thermal-hydraulic code. According to code calculations, flow reversed in the outer flow channel before the maximum wall temperature reached the local fluid saturation temperature. Thermal excursions occurred when the maximum wall temperature approximately equaled the saturation temperature. For a postulated LOPA, the flow reversal criterion for emergency cooling water addition was more limiting than the boiling excursion criterion for full power operation. This criterion limited powers to 37% of the limiting power for previous long-term reactor operations.

  20. Passive systems for buildings using buoyancy-driven airflows

    OpenAIRE

    Abreu, Maria Isabel; Corvacho, Helena; Dias, Ricardo P.

    2011-01-01

    The need for countries to become less dependent on fossil fuels has been a determining factor in recent years due to increasing energy and comfort concerns in modern building design. Therefore, the maximization of the use of renewable energies, like the sun, and the use of natural energy flows become strategies to explore. There are already passive building systems that show interesting performances. Different studies have proved that the above-mentioned systems can lead to important energy s...

  1. Multiple broadly synchronous km-scale exhumation episodes on different continents: implications for controlling processes

    Science.gov (United States)

    Green, Paul; Duddy, Ian; Japsen, Peter

    2015-04-01

    might be magnified by the isostatic response to denudation, but until recently the vertical motions expected from this mechanism were thought to be restricted to 100s of metres while expected timescales of 100s of Myr are not consistent with observations. Braun et al. (2014) showed that movement of plates over areas of areas of mantle upwelling could produce much more rapid uplift and also much larger-scale vertical movements, but the predicted diachroneity of uplift across southern Africa differs from the apparent synchroneity across three continents described here. The processes described by Braun et al. are also specific to one location and one event. Japsen et al. (2012) suggested that broadly synchronous exhumation events on divergent continents resulted from lateral resistance to plate motion driven by forces transmitted in the asthenosphere, while Colli et al. (2014) proposed that dynamic topography caused by pressure-driven mantle flow could produce synchronous uplift (and erosion) in separate continents. Such processes appear to offer more viable mechanisms for producing broadly synchronous episodes of kilometre-scale exhumation and intervening burial in regions separated by large distances. Further geodynamic modelling is needed to develop and test likely mechanisms.

  2. Progressive Extensional Exhumation of the Ultrahigh-Pressure Tso Morari Terrain, NW Indian Himalaya

    Science.gov (United States)

    Hodges, K.; Clark, R.; Monteleone, B.; Sachan, H.; Mukherjee, B. K.; Ahmad, T.

    2011-12-01

    The core of the Tso Morari dome in the Ladakh region of NW India (roughly 33 °10'N; 78°10'E) is one of only two known ultrahigh-pressure (UHP) terrains in the Himalayan-Tibetan orogenic system. The quartzofeldspathic Puga Orthogneiss from the structurally deepest portions of the terrain does not contain UHP mineralogy but surrounds dismembered lenses of mafic eclogite with accessory coesite, confirming that at least the eclogite lenses experienced UHP metamorphic conditions (Mukherjee et al., 2003, International Geology Review; Sachan et al., 2004, European Journal of Mineralogy). U-Pb zircon dates from the Puga orthogneiss (53.3 ± 0.7 Ma: Leech et al., 2007, International Geology Review) provide what appear to be the most precise available constraints on the age of UHP metamorphism at Tso Morari provided we presume that the UHP assemblages in the eclogite lenses developed at the same time as the 53.3 ± 0.7 Ma metamorphic zircon in the orthogneiss. However, other components of the zircon population studied by Leech and co-workers, as well as the results obtained using other thermochronometers and geochronometers (de Sigoyer et al., 2004, Tectonics), demonstrate that a series of lower pressure metamorphic events also affected the Tso Morari terrain between ca. 53 Ma and ca. 45 Ma, implying rapid decompression at elevated temperatures (ca. 800 - 350°C). Our 1:50000-scale geologic mapping at Tso Morari provides evidence that this exhumation was largely accommodated by two previously unrecognized low-angle ductile detachments that separate the terrain into three tectonostratigraphic units with distinctive metamorphic histories. The structurally lowest shear zone (Karla detachment) separates the Puga Orthogneiss from overlying lower amphibolite facies metasedimentary rocks of the Zoboshisha Unit, which contains no UHP assemblages. Structurally higher and demonstrably younger detachments separate the Zoboshisha Unit and the Puga Orthogneiss from greenschist to

  3. Spatiotemporal variation in exhumation of the Crystallines in the NW-Himalaya, India: Constraints from fission track dating analysis

    Science.gov (United States)

    Patel, R. C.; Adlakha, Vikas; Lal, Nand; Singh, Paramjeet; Kumar, Y.

    2011-05-01

    During Himalayan orogeny, coeval thrusting along the Main Central/Munsiari Thrust (MCT/MT) and extension along the South Tibetan-Detachment System (STDS) are widely responsible for rapid exhumation of the Higher Himalayan Crystalline (HHC) zone. Apatite and zircon fission-track data along the Kaliganga and Darma valleys in the Kumaon Himalaya serve to document the shallow bedrock exhumation history of the HHC. Taking into account sample location within the HHC with respect to the MCT/MT, the apatite fission track (AFT) data-sets along the Darma (1.0 ± 0.1 to 2.8 ± 0.3 Ma) and Kaliganga (1.4 ± 0.2 to 2.4 ± 0.3 Ma) which are sharing same structural setting and rock types and being separated by 40 km, show very similar patterns of exhumation histories since Plio-Quaternary in the Kumaon Himalaya. Data sets along Darma and Kaliganga are very similar to data set of adjacent traverse (50 km away) along the Goriganga valley studied by Patel and Carter (2009). Whole data sets within the HHC in Kumaon Himalaya provide clear evidence for Plio-Quaternary tectonic activity along the Vaikrita Thrust (VT). Precipitation in this region exerts a strong influence on erosional surface processes. Fluvial erosional unloading along the Himalaya is focused on the high mountainous region of the HHC, where the orographic barrier forces out the maximum percentage of annual rainfall. FT cooling ages reveal coincidence between rapid erosion and exhumation that is focused in a ~ 25-30 km wide sector of the HHC, rather than covering the entire orogen. Similarity of AFT age pattern and exhumation rates along all three major traverses (Goriganga, Darma and Kaliganga) indicates that the region has been experiencing constant rate of crustal uplift and erosion since long time. Comparison of fission track ages from the Kumaon Himalaya with other segments of the NW-Himalaya shows spatiotemporal variation in exhumation. It is described due to the development of local structures such as dome

  4. Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: response to slab dynamics and erosion

    Science.gov (United States)

    Carrapa, Barbara; Orme, D.A.; DeCelles, Peter G.; Kapp, Paul; Cosca, Michael A.; Waldrip, R.

    2014-01-01

    The India-Asia collision zone in southern Tibet preserves a record of geodynamic and erosional processes following intercontinental collision. Apatite fission-track and zircon and apatite (U-Th)/He data from the Oligocene–Miocene Kailas Formation, within the India-Asia collision zone, show a synchronous cooling signal at 17 ± 1 Ma, which is younger than the ca. 26–21 Ma depositional age of the Kailas Formation, constrained by U-Pb and 40Ar/39Ar geochronology, and requires heating (burial) after ca. 21 Ma and subsequent rapid exhumation. Data from the Gangdese batholith underlying the Kailas Formation also indicate Miocene exhumation. The thermal history of the Kailas Formation is consistent with rapid subsidence during a short-lived phase of early Miocene extension followed by uplift and exhumation driven by rollback and northward underthrusting of the Indian plate, respectively. Significant removal of material from the India-Asia collision zone was likely facilitated by efficient incision of the paleo–Indus River and paleo–Yarlung River in response to drainage reorganization and/or intensification of the Asian monsoon.

  5. Southwest USA Exhumation History Recorded Below the Great Unconformity

    Science.gov (United States)

    Heizler, M. T.; Karlstrom, K. E.

    2002-05-01

    The Southwestern USA Precambrian terranes preserve a long and variable exhumation history that can be tracked using thermochronological methods. This exhumation history is controlled on two interrelated scales. At first order, it is recognized that 1.7 to 1.4 Ga mid-crustal (10 km, 2-4 kbar) rocks were ultimately exhumed and reside below unconformities of variable age. In Arizona, Mesoproterozoic Apache Group and Neoproterozoic Supergroup sedimentary rocks lie directly on basement and thus indicate exhumation of some regions relatively soon following the 1.4 Ga events. In the Rocky Mountains of Colorado and the Rio Grande rift uplifts of New Mexico, basement is generally overlain by Cambrian to Mississippian strata. The unconformities are useful markers of net exhumation; however do not reveal a time-integrated path. Using published, and hundreds of new 40Ar/39Ar analyses of hornblende, muscovite, biotite and K-feldspar, and a growing U/Pb accessory mineral thermochronology database, we are extracting exhumation information with great detail. The thermochronological data continue to support the claim that relatively low net exhumation occurred following 1.7 to 1.6 Ga accretion of volcanic arc terranes to the southern margin of Laurentia. Mid-crustal (2-4 kbar) rocks stabilized soon after accretion, whereas in some regions like the Upper Granite Gorge, Grand Canyon deeper (6 kbar) metamorphic terranes decompressed to 3 kbar before stabilization. The cooling history of these mid-crustal rocks post 1.65 Ga remains somewhat unknown. Overall slow-cooling models (550 \\deg C to 300 \\deg C from 1.7 to 1.4 Ga) require high geothermal gradients in order to maintain 10 km deep rocks at high temperatures for 100's of Ma. Alternatively, isobaric cooling models to more normal geothermal gradients (i.e. 25 \\deg C/km) at ca. 1.65 Ga require later (1.4 Ga) thermal pulses and/or Mesoproterozoic vertical displacements to explain highly discordant thermochronological data. Either

  6. Fluid activity during exhumation of deep-subducted continental plate

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yongfei

    2004-01-01

    It is well known that a great deal of fluid was released during subduction of oceanic crust, resulting in arc magmatism, quartz veining and metamorphic mineralization of syn-subduction. In contrast, the process of continental subduction is characterized by the relative lack of fluid and thus no arc magmatism has been found so far. During exhumation of deep-subducted continental crust, nevertheless,significant amounts of aqueous fluid became available from the decomposition of hydrous minerals, the decrepitation of primary fluid inclusions, and the exsolution of structural hydroxyls. This kind of metamorphic fluid has recently attracted widespread interests and thus been one of the most important targets in deciphering the geological processes concerning metamorphism, magmatism and mineralization in collisional orogens. A large number of studies involving stable isotopes, fluid inclusions and petrological phase relationships have been accomplished in past a few years with respect to the mobility and amount of metamorphic fluid in UHP metamorphic rocks from the Dabie-Sulu orogenic belt.The results demonstrate that the fluid activity during the exhumation of deep-subducted continental crust has the following effects: (1) amphibolite-facies retrogression due to pervasive fluid flow; (2) formation of HP quartz veins within eclogites due to channelized fluid flow; and (3) partial melting of overlying crustal rocks due to focused fluid flow, producing syn-exhumation magmatism within the orogenic belt.In particular, the aqueous fluid released by decompression exsolution of hydroxyl from UHP minerals is characterized by low salinity and is capable of resulting in pervasive and channellized flow. Therefore, the intensive study of fluid activity during exhumation of UHP metamorphic rocks can not only provide insight into geodynamic processes that occurred in continental collisional belts, but also shed light on understanding of crust-mantle recycling and relevant magmatism in

  7. [Identification of an exhumed unknown infant through DNA analysis].

    Science.gov (United States)

    Jopp, Eilin; Püschel, Klaus; Warschke, Christian; Kaufmann, Richard; Krebs, Oliver

    2014-01-01

    The article reports on the exhumation and subsequent DNA analysis of the skeletal remains of an unknown male newborn from 1988. Molecular biological methods confirmed the maternity of a woman who was already convicted of infanticide. Since homicide could not be clearly proven and manslaughter becomes barred by the statute of limitation after 20 years, the woman cannot be held accountable for the alleged killing of her first child. PMID:25004622

  8. Late Cenozoic exhumation and timing of the deformation front of the Kashmir Himalayas from U-Th/(He) thermochronometry

    Science.gov (United States)

    Gavillot, Y. G.; Meigs, A.; Stockli, D. F.; Malik, M. M.

    2013-12-01

    Apatite and zircon (U-Th)/He cooling ages are used to quantify the recent exhumation pattern associated with fault activity across the Kashmir Himalayas. Here we present data from thirty samples, totaling of 74 individual single-grain apatite and zircon dated aliquots. Cooling age data were collected from (1) molasse sediments of the Murree and Siwalik Formations from structures in the Sub-Himalayan belt (deformed foreland) and from (2) metasediments and plutonic rocks exhumed in the 'hinterland'. Structures of the Sub-Himalayan belt include the Suruin-Mastgarh anticline (SMA) at the deformation front, equivalent to the Himalayan Frontal thrust (HFT), and emergent local faults to the north (e.g. the Riasi thrust (RT)). In the hinterland, the Main Boundary (MBT) and Main Central (MCT) thrust sheets bound the Sub-Himalayan belt to the north. Apatite (U-Th)/He (AHe) cooling ages for the molasses sediments are consistently younger than the sediment age indicating that Sub-Himalayan belt samples are reset. Mean cooling age data based on the single grain populations from each sample ranges from ~1-10 Ma. Single grain and mean age probability density plots reveal a period of rapid cooling and exhumation between 1.8-2.75 Ma throughout the Sub-Himalaya. Distributed deformation associated with northward underthrusting along the MHT, and the onset of folding related to the SMA explains the regional exhumation of the Sub-Himalaya after ~2.75 Ma. Four samples from the hinterland MBT and MCT thrust sheets yield AHe cooling ages between ~5-21 Ma. Three of the samples have cooling ages between 4.7-7.2 Ma, likely coeval with activity of the MBT. Zircon (U-Th)/He (ZHe) samples from the hinterland are younger than the ages of the metasedimentary or plutonic source rocks. Most sample ages from the Sub-Himalaya are older or the same to the depositional age and are therefore detrital. Probability density plots of hinterland ZHe data show a pronounced spike in cooling between 16-21 Ma

  9. An exhumed Late Paleozoic canyon in the rocky mountains

    Science.gov (United States)

    Soreghan, G.S.; Sweet, D.E.; Marra, K.R.; Eble, C.F.; Soreghan, M.J.; Elmore, R.D.; Kaplan, S.A.; Blum, M.D.

    2007-01-01

    Landscapes are thought to be youthful, particularly those of active orogenic belts. Unaweep Canyon in the Colorado Rocky Mountains, a large gorge drained by two opposite-flowing creeks, is an exception. Its origin has long been enigmatic, but new data indicate that it is an exhumed late Paleozoic landform. Its survival within a region of profound late Paleozoic orogenesis demands a reassessment of tectonic models for the Ancestral Rocky Mountains, and its form and genesis have significant implications for understanding late Paleozoic equatorial climate. This discovery highlights the utility of paleogeomorphology as a tectonic and climatic indicator. ?? 2007 by The University of Chicago. All rights reserved.

  10. Magmatism as a response to exhumation of the Priest River complex, northern Idaho: Constraints from zircon U-Pb geochronology and Hf isotopes

    Science.gov (United States)

    Stevens, L. M.; Baldwin, J. A.; Crowley, J. L.; Fisher, C. M.; Vervoort, J. D.

    2016-10-01

    Zircon and monazite U-Pb geochronology and zircon Hf isotopes place constraints on the temporal and source relationships between crustal anatexis, magmatism, and exhumation of the Priest River metamorphic core complex, northern Idaho. Granitoids that intruded the migmatitic, pelitic Hauser Lake gneiss include the < 76.5 ± 0.1 Ma Spokane granite, 50.13 ± 0.02 Ma Silver Point quartz monzonite, c. 47.9 Ma Wrencoe granodiorite, < 46.4 ± 1.8 Ma Rathdrum granite, and a < 49.8 ± 0.4 Ma leucocratic dike. Cretaceous magmatism preceded the c. 64 Ma peak metamorphism (recorded by monazite) of the Hauser Lake gneiss, whereas discrete pulses of Eocene magmatic activity post-date the onset of exhumation by 10 Ma. The relative timing of pluton emplacement in the Priest River complex indicates that it was primarily a response to decompression rather than a cause. The mylonitized Silver Point and undeformed Wrencoe plutons bracket the end of a rapid phase of exhumation to c. 50-48 Ma. Zircon εHf(i) values and Lu-Hf isotope evolution indicate that the Silver Point and Wrencoe plutons crystallized from homogeneous magmas sourced from Archean-Proterozoic basement orthogneisses, whereas the Spokane granite and two leucocratic units appear to have been produced by partial melting of the Hauser Lake gneiss. Comparison of the Priest River complex with other deeply exhumed northern Cordilleran complexes indicates variability in the timing and, therefore, relative influences of partial melting and magmatism on the initiation of exhumation, which must be accounted for in numerical models of metamorphic core complex formation and evolution.

  11. How Orogen-scale Exhumed Strike-slip Faults Initiate

    Science.gov (United States)

    Cao, S.; Neubauer, F.

    2015-12-01

    Orogen-scale strike-slip faults present one the most important geodynamic processes affecting the lithosphere-asthenosphere system. In specific subtypes, faulting is virtually initiated along hot-to-cool boundaries, e.g. at such of hot granite intrusions or metamorphic core complexes to cool country rocks. Such fault zones are often subparallel to mountain ranges and expose a wide variety of mylonitic, cataclastic and non-cohesive fault rocks, which were formed at different structural levels of the crust and are stacked within each other ("telescoping"). Exhumation of rocks is, therefore, a common feature of such strike-slip faults implying major transtensive and/or transpressive processes accompanying pure strike-slip motion. The hot-to-cool thermal structure across the fault zone significantly influences the physical fault rock properties. One major question is how and where a major strike-slip initiates and further development. Here, we propose a model in which major continental exhumed strike-slip faults potentially evolve along rheologically weak zones such as plutons or margins of metamorphic complexes. As an example, we propose a model for the Ailao Shan-Red River (ASRR) fault, SE Asia, which initiated along the edge of a plutonic belt and evolved in response to India-Asia collision with four tectonic phases.

  12. Extreme mantle uplift and exhumation along a transpressive transform fault

    Science.gov (United States)

    Maia, Marcia; Sichel, Susanna; Briais, Anne; Brunelli, Daniele; Ligi, Marco; Ferreira, Nicolas; Campos, Thomas; Mougel, Bérengère; Brehme, Isa; Hémond, Christophe; Motoki, Akihisa; Moura, Denise; Scalabrin, Carla; Pessanha, Ivo; Alves, Eliane; Ayres, Arthur; Oliveira, Pedro

    2016-08-01

    Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults, and, along transforms, by transtension due to changes in ridge/transform geometry. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic. Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since ~10 million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform fault creating restraining stepovers. An anticlockwise change in plate motion at ~11 million years ago initially favoured extension in the left-stepping transform, triggering the formation of a transverse ridge, later uplifted through transpression, forming the St Peter and St Paul islets. Enhanced melt supply at the ridge axis due to the nearby Sierra Leone thermo chemical anomaly is responsible for the robust response of the northern Mid-Atlantic Ridge segment to the kinematic change. The long-lived process at the origin of the compressive stresses is directly linked to the nature of the underlying mantle and not to a change in the far-field stress regime.

  13. Early Cenozoic "dome like" exhumation around the Irish Sea

    Science.gov (United States)

    Doepke, Daniel; Cogné, Nathan; Chew, David; Stuart, Fin

    2016-04-01

    Despite decades of research the Early Cenozoic exhumation history of Ireland and Britain is still poorly understood and subject to contentious debate (see Davis et al., 2012 and subsequent comments). Previous studies have attributed the Cenozoic exhumation history of Ireland and Britain mainly to: (a) Paleogene - Neogene far-field stress between the opening of the North Atlantic Ocean and the Alpine collision (Ziegler et al., 1995; Hillis et al., 2008) or (b) early Paleogene mantle driven magmatic underplating associated with the development of the proto-Iceland mantle plume beneath the Irish Sea (Brodie and White, 1994; Al-Kindi et al., 2003). The major differences between the two hypotheses are the pattern and timing of spatial exhumation. This project thus seeks to investigate the timing and mechanisms of late Mesozoic - early Cenozoic exhumation on the onshore part of the British Isles by using a combination of apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) data, which we then model using the QTQt program of Gallagher (2012) to better constrain the modelled thermal histories. Our studied area centres on the margins of the Irish Sea, but includes all Ireland and western Britain. Overall we analysed 74 samples for AFT and 66 samples for AHe dating. In particular, our results include ten pseudo-vertical profiles. The AFT ages display a wide range of ages from early Carboniferous in Scotland to early Eocene in central Ireland. Our AHe ages range from mid Permian on Shetland to Eocene Ft-corrected. The AFT data do not show any specific spatial distribution, however, the Ft-corrected AHe ages around the Irish Sea only focus around late Cretaceous to Eocene suggesting an important thermal event around this time. The modelled thermal histories of samples located around the Irish Sea and western Scotland show a clear late Cretaceous to early Paleogene cooling event which is not present elsewhere. The distribution of this cooling event is broadly consistent

  14. White mica K-Ar geochronology of HP-UHP units in the Lago di Cignana area, western Alps, Italy: Tectonic implications for exhumation

    Science.gov (United States)

    Gouzu, Chitaro; Yagi, Koshi; Thanh, Ngo Xuan; Itaya, Tetsumaru; Compagnoni, Roberto

    2016-04-01

    High-pressure and ultra-high pressure (HP-UHP) blueschist- and eclogite-facies metabasaltic and metasedimentary rocks occur in four different tectonic units near Lago di Cignana, western Alps. We have determined K-Ar ages for white micas (matrix phengite and paragonite) from the Lago di Cignana UHP unit (LCU; 39-41 Ma); the lower and upper units of the Zermatt-Saas meta-ophiolite (LU and UU; 37-38 Ma and 38-41 Ma respectively), and the Combin unit (CU; 36-40 Ma). These K-Ar ages overlap with single-grain Ar-Ar plateau ages (36-42 Ma) previously determined for phengites from LCU metasediments. Matrix white micas have been severely deformed during exhumation, and their chemistries differ from those of micas included in garnet. Although individual mica grains in the matrix could have experienced different degrees of deformation which have reset their K-Ar systems, "bulk" white mica separates provide the average age of all the individual grains in the separate. The similarity of ages determined for white micas from the LCU, LU, UU and CU units, regardless of rock type and mineral species, suggests that these four units were metamorphosed together as part of a single metamorphic sequence in the Piemonte-Liguria paleosubduction zone and were subsequently exhumed together. However, present-day structural relationship among those units and the limited occurrence of UHP minerals in LCU suggests that the exhumation of LCU was more rapid than that for LU, UU and CU. The age gaps between the youngest value of white mica K-Ar ages in each unit and the inferred timing of the metamorphic peak (U-Pb age: 44 Ma) is 5, 7, 6 and 8 Myr for LCU, LU, UU and CU, respectively. These intervals are considerably shorter than that determined for the Sanbagawa HP metamorphic belt of Southwest Japan (> 31 Myr). The short interval observed for the Lago di Cignana units that we have studied is consistent with the model of rapid exhumation of the UHP-bearing metamorphic domain, suggesting the

  15. Large along-strike variations in the onset of Subandean exhumation: Implications for Central Andean orogenic growth

    Science.gov (United States)

    Lease, Richard O.; Ehlers, Todd A.; Enkelmann, Eva

    2016-10-01

    Plate tectonics drives mountain building in general, but the space-time pattern and style of deformation is influenced by how climate, geodynamics, and basement structure modify the orogenic wedge. Growth of the Subandean thrust belt, which lies at the boundary between the arid, high-elevation Central Andean Plateau and its humid, low-elevation eastern foreland, figures prominently into debates of orogenic wedge evolution. We integrate new apatite and zircon (U-Th)/He thermochronometer data with previously published apatite fission-track data from samples collected along four Subandean structural cross-sections in Bolivia between 15° and 20°S. We interpret cooling ages vs. structural depth to indicate the onset of Subandean exhumation and signify the forward propagation of deformation. We find that Subandean growth is diachronous south (11 ± 3 Ma) vs. north (6 ± 2 Ma) of the Bolivian orocline and that Subandean exhumation magnitudes vary by more than a factor of two. Similar north-south contrasts are present in foreland deposition, hinterland erosion, and paleoclimate; these observations both corroborate diachronous orogenic growth and illuminate potential propagation mechanisms. Of particular interest is an abrupt shift to cooler, more arid conditions in the Altiplano hinterland that is diachronous in southern Bolivia (16-13 Ma) vs. northern Bolivia (10-7 Ma) and precedes the timing of Subandean propagation in each region. Others have interpreted the paleoclimate shift to reflect either rapid surface uplift due to lithosphere removal or an abrupt change in climate dynamics once orographic threshold elevations were exceeded. These mechanisms are not mutually exclusive and both would drive forward propagation of the orogenic wedge by augmenting the hinterland backstop, either through surface uplift or spatially variable erosion. In summary, we suggest that diachronous Subandean exhumation was driven by piecemeal hinterland uplift, orography, and the outward

  16. Surface wave tomography of D'Entrecasteaux Islands, Papua New Guinea, implication of mantle control on localization of extension and exhumation

    Science.gov (United States)

    Jin, G.; Gaherty, J. B.; Abers, G. A.; Kim, Y.; Eilon, Z.; Buck, W. R.; Verave, R.

    2013-12-01

    The Woodlark rift system is propagating westward into the Australian plate near Papua New Guinea. The current tip is located east of the D'Entrecasteaux Islands (DEI), where very young ultra-high pressure rocks found within metamorphic core complexes suggest rapid exhumation from ~100km depth in 5%) at shallow depth (Moho to 60km) west of the region of recent extension and exhumation (DEI), while underneath the DEI, the slow anomaly appears to be much deeper (>60km). The shallow low-velocity body in the west roughly parallels both the Trobriand Trench and the Mesozoic-era Australia-Pacific collision zone, and also lies between the current rift tip and the dominant Euler pole (6-0.5Ma) of Woodlark-Australia plate rotation. It may reflect relatively high mantle temperatures beneath the modern (<10Ma) volcanic system that includes Mt. Victory and Mt. Lamington, both of which erupted during the last century. This existing volcanic system may produce a weak zone that helps to localize the extension. As a result, the westward propagation of the Woodlark rift follows and tears apart this volcanic system, and the extension environment enables rapid exhumation driven by buoyant, partially molten upper mantle, as predicted by the diapir model. The deeper low-velocity body underneath the DEI can be explained by rift-system-induced mantle upwelling.

  17. Variscan to Neogene thermal and exhumation history at the Moroccan passive continental margin assessed by low temperature thermochronology

    Science.gov (United States)

    Sehrt, M.; Glasmacher, U. A.; Stockli, D. F.; Kluth, O.; Jabour, H.

    2012-04-01

    In North Africa, a large amount of Mesozoic terrigenous sedimentary rocks are deposited in most of the basins along the continental margin indicating a major episode of erosion occurred during the rift and early post-rift period in the Central Atlantic. In the Tarfaya-Dakhla Basin, Morocco the sedimentary cover reaches thicknesses of up to 9000 m. The presence of high surface elevations in the Anti-Atlas mountain belt (2500 m) indicates a potential source area for the surrounding basins. The NE-SW oriented Anti-Atlas of Morocco is located at the northwestern fringe of the West African Craton and south of the High Atlas and represents the Phanerozoic foreland of the Late Paleozoic North African Variscides and the Cenozoic Atlas Belt. Variscan deformation affected most of Morocco. Paleozoic basins were folded and thrusted, with the major collision dated as late Devonian to Late Carboniferous. Zircon fission-track ages of 287 (±23) to 331 (±24) Ma confirmed the main exhumation referred to the Variscan folding, followed by rapid exhumation and the post-folding erosion. Currently, phases of uplift and exhumation in the Anti-Atlas during the Central Atlantic rifting and places where the associated erosion products are deposited are poorly constrained and there is little quantitative data available at present. The objective of the study is to determine the thermal and exhumation history of the Anti-Atlas and the connected Tarfaya-Dakhla Basin at the Moroccan passive continental margin. Besides zircon fission-track dating, apatite and zircon (U-Th-Sm)/He and apatite fission-track analyses and furthermore 2-D modelling with 'HeFTy' software has been carried out at Precambrian rocks of the Western Anti-Atlas and Cretaceous to Neogene sedimentary rocks from the Northern Tarfaya-Dakhla Basin. The apatite fission-track ages of 120 (±13) to 189 (±14) Ma in the Anti-Atlas and 176 (±20) to 216 (±18) Ma in the Tarfaya Basin indicate very obvious a Central Atlantic opening

  18. Unraveling tectonics and climate forcing in the late-Neogene exhumation history of South Alaska

    Science.gov (United States)

    Valla, Pierre; Champagnac, Jean-Daniel; Shuster, David; Herman, Frédéric; Giuditta Fellin, Maria

    2015-04-01

    The southern Alaska range presents an ideal setting to study the complex interactions between tectonics, climate and surface processes in landscape evolution. It exhibits active tectonics with the ongoing subduction/collision between Pacific and North America, and major active seismogenic reverse and strike-slip faults. The alpine landscape, rugged topography and the important ice-coverage at present reveal a strong glacial imprint associated with high erosion and sediment transport rates. Therefore, the relative importance of climatically-driven glacial erosion and tectonics for the observed late-exhumation history appears to be quite complex to decipher. Here, we first perform a formal inversion of an extensive bedrock thermochronological dataset from the literature to quantify the large-scale 20-Myr exhumation history over the entire southern Alaska. We show that almost half of the variability within the thermochronological record can be explained by modern annual precipitations spatial distribution, the residuals clearly evidencing localized exhumation along major tectonic structures of the frontal fold and thrust belt. Our results confirm high exhumation rates in the St Elias "syntaxis" and frontal zones for the last 0-2 Myr, where major ice fields and high precipitation rates likely sustained high exhumation rates; however the impact of late Cenozoic glaciations is difficult to constrain because of the low resolution on the exhumation history older than ~2 Myr. On the contrary, our inversion outcomes highlight that north of the Bagley Icefield the long-term exhumation has remained quite slow and continuous over the last ~20 Myr, with no late-stage signal of exhumation change since the onset of glaciations despite a clear glacial imprint on the landscape. We thus focus on the Granite Range (Wrangell-St Elias National Park, Alaska), an area presenting a strong glacial imprint but minor tectonic activity with only localized brittle deformation. We sampled four

  19. 40Ar/39Ar geochronology and exhumation of mylonitized metamorphic complex in Changle-Nanao ductile shear zone

    Institute of Scientific and Technical Information of China (English)

    王志洪; 卢华复

    1997-01-01

    New 40Ar/39Ar plateau ages from rocks of Changle-Nanao ductile shear zone are 107.9 Ma(Mus), 108.2 Ma(Bi), 107. 1 Ma(Bi), 109. 2 Ma(Hb) and 117. 9 Ma(Bi) respectively, which are concordant with their isochron ages and record the formation age of the ductile shear zone. The similarity and apparent overlap of the cooling ages with respective closure temperatures of 5 minerals document initial rapid uplift during 107-118 Ma following the collision between the Min-Tai microcontinent and the Min-Zhe Mesozoic volcanic arc. The 40Ar/39Ar plateau ages, K-Ar date of K-feldspar and other geochronologic information suggest that the exhumation rate of the ductile shear zone is about 0.18-1.12 mm/a in the range of 107-70 Ma, which is mainly influenced by tectonic extension.

  20. Resolving spatial heterogeneities in exhumation and surface uplift in Timor-Leste : Constraints on deformation processes in young orogens

    OpenAIRE

    Tate, Garrett W.; McQuarrie, Nadine; D. J. J. van Hinsbergen; Bakker, Richard R.; Harris, Ron; Willett, Sean; Reiners, Peter W.; Fellin, Maria Giuditta; Ganerød, Morgan; Zachariasse, Willem Jan

    2014-01-01

    Although exhumation and surface uplift are important parameters in understanding orogenesis, the opportunity to measure both in close proximity is rare. In Timor-Leste (East Timor), deeply exhumed metamorphic rocks and piggyback deepwater synorogenic basins are only tens of kilometers apart, permitting direct relation of uplift and exhumation by comparing micropaleontology to thermochronology interpreted through one-dimensional thermal modeling. Foraminifera in two deepwater synorogenic basin...

  1. Structural Geology and Exhumation of the Paleogene Southern Sivas Fold and Thrust Belt, Central Anatolia, Turkey

    Science.gov (United States)

    Darin, M. H.; Umhoefer, P. J.; Lefebvre, C.; Thomson, S. N.

    2015-12-01

    The Anatolian plate (Turkey) was formed during the late Miocene-Pliocene transition from contractional strain in central and eastern Anatolia (collision) to localized strike-slip faulting along inherited collisional structures (escape tectonics). Structural inheritance undoubtedly played a role in this major plate boundary reorganization, although its significance is not well understood. Considerable uncertainty also exists regarding the timing and kinematics of Tauride-Eurasia collision, initial Arabia-Eurasia collision, and the terminal closure of the Neotethys Ocean. The Sivas Basin is a ~E-W-elongate collisional forearc basin located between the Tauride micro-continent in the south and the Pontide Arc along the southern Eurasian margin in the north. Well-exposed contractional structures in Paleocene-Eocene marine strata of the Southern Sivas fold and thrust belt (SSFTB) provide an excellent opportunity to investigate the timing and kinematics of both Tauride and Arabian collisions and their potential roles in localizing strain and facilitating tectonic escape. We use detailed geologic mapping, structural analysis and detrital geo/thermochronology to investigate the magnitude, style, and timing of collision-related crustal shortening across the SSFTB. The structural geology of the SSFTB is characterized by ENE- to ESE-trending, gently plunging fault propagation folds with slight asymmetry towards the north. Vergence on thrust faults is mainly towards the north, although a few previously unmapped faults are south-vergent. Detrital apatite fission track data from Paleocene-Eocene strata reveal a single phase of rapid exhumation ca. ~36-31 Ma, which may be related to either Tauride or initial Arabian collision. We propose that structural growth of the SSFTB at this time played a major role in marine basin isolation and early Oligocene evaporite deposition. In the central and northern Sivas Basin where salt was likely thickest, salt tectonics was initiated by

  2. Mycoflora in Exhumed Seeds of Opuntia tomentosa and Its Possible Role in Seed Germination

    Directory of Open Access Journals (Sweden)

    María Esther Sánchez-Coronado

    2011-01-01

    Full Text Available The funicular cover of the Opuntia tomentosa seed limits imbibition; germination occurs only when the funicle is weakened or the funicular valve is removed. We investigated the role of fungi in funicular weakening and seed germination. Seeds that had been either buried in one of two sites or stored in the laboratory were germinated with and without a valve. Disinfected or nondisinfected seeds and their naked embryos were cultivated on agar or PDA. None of the 11 identified fungal genera grew on the disinfected control seeds or the embryos. The mycoflora present on disinfected and nondisinfected exhumed seeds suggest that the fungal colonization occurred in the soil and differed between the burial sites. Exhumed seeds with and without a valve germinated in high percentages, whereas only the control seeds without a valve germinated. Scanning electron micrographs showed that the hyphae penetrated, cracked, and eroded the funicular envelope of exhumed seeds.

  3. Effect of horseshoe crab spawning density on nest disturbance and exhumation of eggs: A simulation study

    Science.gov (United States)

    Smith, D.R.

    2007-01-01

    Because the Delaware Bay horseshoe crab (Limulus polyphemus) population is managed to provide for dependent species, such as migratory shorebirds, there is a need to understand the process of egg exhumation and to predict eggs available to foraging shorebirds. A simple spatial model was used to simulate horseshoe crab spawning that would occur on a typical Delaware Bay beach during spring tide cycles to quantify density-dependent nest disturbance. At least 20% of nests and eggs were disturbed for levels of spawning greater than one third of the average density in Delaware Bay during 2004. Nest disturbance increased approximately linearly as spawning density increased from one half to twice the 2004 level. As spawning density increased further, the percentage of eggs that were disturbed reached an asymptote of 70% for densities up to 10 times the density in 2004. Nest disturbance was heaviest in the mid beach zone. Nest disturbance precedes entrainment and begins the process of exhumation of eggs to surface sediments. Model predictions were combined with observations from egg surveys to estimate a snap-shot exhumation rate of 5-9% of disturbed eggs. Because an unknown quantity of eggs were exhumed and removed from the beach prior to the survey, cumulative exhumation rate was likely to have been higher than the snap-shot estimate. Because egg exhumation is density-dependent, in addition to managing for a high population size, identification and conservation of beaches where spawning horseshoe crabs concentrate in high densities (i.e., hot spots) are important steps toward providing a reliable food supply for migratory shorebirds. ?? 2007 Estuarine Research Federation.

  4. Significance of "stretched" mineral inclusions for reconstructing P- T exhumation history

    Science.gov (United States)

    Ashley, Kyle T.; Darling, Robert S.; Bodnar, Robert J.; Law, Richard D.

    2015-06-01

    Analysis of mineral inclusions in chemically and physically resistant hosts has proven to be valuable for reconstructing the P- T exhumation history of high-grade metamorphic rocks. The occurrence of cristobalite-bearing inclusions in garnets from Gore Mountain, New York, is unexpected because the peak metamorphic conditions reached are well removed (>600 °C too cold) from the stability field of this low-density silica polymorph that typically forms in high temperature volcanic environments. A previous study of samples from this area interpreted polymineralic inclusions consisting of cristobalite, albite and ilmenite as representing crystallized droplets of melt generated during a garnet-in reaction, followed by water loss from the inclusion to explain the reduction in inclusion pressure that drove the transformation of quartz to cristobalite. However, the recent discovery of monomineralic inclusions of cristobalite from the nearby Hooper Mine cannot be explained by this process. For these inclusions, we propose that the volume response to pressure and temperature changes during exhumation to Earth's surface resulted in large tensile stresses within the silica phase that would be sufficient to cause transformation to the low-density (low-pressure) form. Elastic modeling of other common inclusion-host systems suggests that this quartz-to-cristobalite example may not be a unique case. The aluminosilicate polymorph kyanite also has the capacity to retain tensile stresses if exhumed to Earth's surface after being trapped as an inclusion in plagioclase at P- T conditions within the kyanite stability field, with the stresses developed during exhumation sufficient to produce a transformation to andalusite. These results highlight the elastic environment that may arise during exhumation and provide a potential explanation of observed inclusions whose stability fields are well removed from P- T paths followed during exhumation.

  5. [Approaches to setting up the Center for identification of exhumed bodies in Chechen Republic].

    Science.gov (United States)

    Klevno, V A; Ivanov, P L

    2007-01-01

    The authors participated in the activity of a group of European experts who visited Moscow, Rostov-on-Don and Grozny in September 2005 to clarify situation with identification of exhumed unknown dead bodies of the civil population. The European experts recommend to set up Center for Identification in Chechen Republic (in Grozny). The authors propose to make DNA identification tests in the Russian Federation Center for Forensic Medical Evaluation in Moscow which has much experience and staff skilled in identification of unknown exhumed bodies and can solve the problem of genetic identification of unidentified bodies of people missed in the Chechen Republic more effectively.

  6. Cooling and exhumation of continents at billion-year time scales

    Science.gov (United States)

    Blackburn, T.; Bowring, S. A.; Perron, T.; Mahan, K. H.; Dudas, F. O.

    2011-12-01

    The oldest rocks on Earth are preserved within the continental lithosphere, where assembled fragments of ancient orogenic belts have survived erosion and destruction by plate tectonic and surface processes for billions of years. Though the rate of orogenic exhumation and erosion has been measured for segments of an orogenic history, it remains unclear how these exhumation rates have changed over the lifetime of any terrane. Because the exhumation of the lithospheric surface has a direct effect on the rate of heat loss within the lithosphere, a continuous record of lithosphere exhumation can be reconstructed through the use of thermochronology. Thermochronologic studies have typically employed systems sensitive to cooling at temperatures recycling of these shallow rocks results in a poor preservation potential of any long-term record. Here, an ancient and long-term record of lithosphere exhumation is constructed using U-Pb thermochronology, a geochronologic system sensitive to cooling at temperatures found at 20-50 km depth (400-650 °C). Lower crustal xenoliths provide material that resided at these depths for billions of years or more, recording a thermal history that is buried deep enough to remain insensitive to upper crustal deformation and instead is dominated by the vertical motions of the continents. We show how this temperature-sensitive system can produce a long-term integrated measure of continental exhumation and erosion. Preserved beneath Phanerozoic sedimentary rocks within Montana, USA, the Great Falls Tectonic Zone formed when two Archean cratons, the Wyoming Province and Medicine Hat Block collided at ~1.8 Ga. Rutile U-Pb data from multiple xenoliths, each exhumed from a different depth within the crustal column reveal a range of dates that varies as a function of xenolith residence depth. The shallowest mid- to lower crustal xenoliths (~25 km) cooled first, yielding the youngest dates and yet cooled at rates between 0.1-0.25 °C/Ma over 500 My or

  7. Resolving spatial heterogeneities in exhumation and surface uplift in Timor-Leste : Constraints on deformation processes in young orogens

    NARCIS (Netherlands)

    Tate, Garrett W.; McQuarrie, Nadine; van Hinsbergen, D.J.J.; Bakker, Richard R.; Harris, Ron; Willett, Sean; Reiners, Peter W.; Fellin, Maria Giuditta; Ganerød, Morgan; Zachariasse, Willem Jan

    2014-01-01

    Although exhumation and surface uplift are important parameters in understanding orogenesis, the opportunity to measure both in close proximity is rare. In Timor-Leste (East Timor), deeply exhumed metamorphic rocks and piggyback deepwater synorogenic basins are only tens of kilometers apart, permitt

  8. Exhumation of high-pressure rocks in a Variscan migmatite dome (Montagne Noire, France)

    Science.gov (United States)

    Whitney, Donna; Roger, Francoise; Rey, Patrice; Teyssier, Christian

    2015-04-01

    of garnet rims presents a challenge for ascribing the zircon rim age to hydrothermal alteration. Of the 5 reported eclogite localities in the MN, 4 are located near a high-strain zone along the long axis of the dome and one is located in a shear zone at the SSW margin of the gneissic core. 2D and 3D numerical models show that migmatite domes may form in response to extension of the upper crust, as the partially molten deep crust ascends along a steep, axial high strain zone and then flows into subdomes flanking this zone, forming a double dome such as the MN. This mode of dome formation is an efficient mechanism for rapid exhumation of deep crust. Migmatite dome rocks equilibrate at LP/HT, but eclogite inclusion in migmatite preserve their deep origin, track exhumation, and inform the internal dynamics of domes. Domes like the MN demonstrate that the opportunistic low-viscosity deep crust flows readily to fill gaps created by extensional/ transtensional domains in the collapsing late-Variscan orogen.

  9. Application of low-temperature thermochronology to hydrothermal ore deposits: Formation, preservation and exhumation of epithermal gold systems from the Eastern Rhodopes, Bulgaria

    Science.gov (United States)

    Márton, István; Moritz, Robert; Spikings, Richard

    2010-03-01

    New low-temperature thermochronological data have been used to quantify the protracted, Eocene-Miocene cooling histories of upper and lower plate rocks of the Kesebir-Kardamos extensional dome, Eastern Rhodopes, Bulgaria. 40Ar/ 39Ar and apatite fission-track data reveal that the lower plate has experienced continuous cooling and exhumation, since the Late Eocene. Muscovite 40Ar/ 39Ar plateau ages of 36.90 ± 0.16 Ma and 37.28 ± 0.19 Ma (2 σ) from metamorphic rocks of the footwall reveal the approximate time span during which they cooled below ˜ 350 °C during exhumation caused by detachment faulting. The sedimentary rock-hosted gold mineralization, which represents a thermal event at ˜ 250-220 °C, developed during the early stage of basin formation between 34.71 ± 0.16 Ma and 35.36 ± 0.21 Ma (adularia 40Ar/ 39Ar plateau ages; 2 σ). The termination of hydrothermal mineral deposition at Ada Tepe occurred contemporaneously with the earliest phase of calc-alkaline type magmatism at Iran Tepe (33.97 ± 0.36 Ma to 34.62 ± 0.46 Ma, hornblende and biotite 40Ar/ 39Ar plateau ages, 2 σ). Thermal history modelling of apatite fission-track data shows that the lower plate rocks cooled through ˜ 120 °C at ˜ 18.3 ± 1.9 Ma (1 σ). A time-temperature model obtained from zircon and apatite fission-track data from the upper plate reveals that it was being buried during the late Eocene. At ˜ 33-30 Ma, a dramatic change of the time-temperature path was caused by the initiation of horst-graben structures, resulting in rapid exhumation of the upper plate. Our new thermochronological data reveal many aspects of the mechanisms of formation of sedimentary rock-hosted gold deposits. The heat accumulated during sedimentary burial of the upper plate is a plausible heat source to drive hydrothermal fluid circulation and ore formation. The development of large half-graben basins in the hanging walls of detachment faults, accompanied by a favourable climate, may have created a

  10. Mechanisms of continental subduction and exhumation of HP and UHP rocks

    NARCIS (Netherlands)

    Burov, Evgene; Francois, Thomas; Yamato, Philippe; Wolf, Sylvie

    2014-01-01

    We discuss possible scenarios of continental collision, and their relation to mechanisms of exhumation of HP and UHP rocks, inferred from thermo-mechanical numerical models accounting for thermo-rheological complexity of the continental lithosphere. Due to this complexity, mechanisms of continental

  11. Long-term subsidence, cooling, and exhumation history along the South Atlantic passive continental margin in NW-Namibia

    Science.gov (United States)

    Menges, Daniel; Glasmacher, Ulrich Anton; Salomon, Eric; Hackspacher, Peter Christian; Schneider, Gabi

    2016-04-01

    In northwest Namibia the Kaoko Belt is one of the most important Precambrian crustal segments that have stored the subsidence, cooling, and exhumation history of Namibia since the Neoproterozoic. ZFT-ages are processed to give new insights on this early evolution. Paleozoic to Mesozoic sedimentary rocks of the Karoo Supergroup and the Lower Cretaceous volcanic rocks of the Etendeka sequence overlay the Proterozoic metamorphic and intrusive rocks (1). New apatite fission-track (AFT) ages range from 390.9 (17.9) Ma to 80.8 (6.0) Ma. Along the coast apatites of Proterozoic rock samples reveal the youngest ages. Further inland the ages increase significantly. In addition, rapid change of AFT-ages occurs on both sides of major thrust and shear zones. Using the oldest thermochronological data the revealed t-T paths indicate a long era of exhumation, starting at the end of the Pan-African Orogeny in the Neoproterozoic and continuing into the Permo-Carboniferous. The subsequent sedimentation of the Karoo Supergroup initiates a new era of subsidence until the end of Triassic (2). The subsequent period of denudation ends abruptly with the rapid deposition of the Etendeka basalts in the Early Cretaceous (3). The maximum thickness of the Etendeka volcanic suite has been estimated, using the apatite fission-track data, to about 3.2 (1.2) km. With the ongoing opening of the South Atlantic and the formation of the continental margin the Kaoko Belt went through a rapid cooling event starting ~ 130 Ma and ending ~ 80 Ma, at a mean rate of 0.034 km/Ma for the western, and 0.018 km/Ma for the northern and eastern Kaoko Belt. This cooling event was accompanied by a reactivation of major fault zones, like the Purros Mylonite Zone (4). Thereafter, stable conditions were established, with denudation rates generally lower than 0.010 km/Ma, until the Neogene, where a second cooling event led to increased exhumation rates around 0.042 km/Ma. The total amount of denudation in the last 130 Ma

  12. Late-Quaternary exhumation rates constrained by OSL thermochronometry at the Franz Josef Glacier, New Zealand

    Science.gov (United States)

    Duverger, Arnaud; King, Georgina; Valla, Pierre; Cox, Simon; Herman, Frederic

    2016-04-01

    The Southern Alps of New Zealand are often cited as the primary example of a mountain range that has reached exhumation and topographic steady state, especially on the West Coast where exhumation rates reach up to about 10 mm/yr. However, cyclic climatic changes, throughout the Quaternary period have meant that the Alps cycled between being completely glaciated and ice free. The impact that such glacial cycles may have had on the spatial variability of erosion rates remains poorly constrained. Here we use Optically Stimulated Luminescence (OSL) as a very low temperature thermochronometer to constrain rock cooling histories at 10-100 kyr timescales on samples collected near the Franz Josef glacier. OSL-thermochronometry is based on the amount of electrons accumulated in the lattice defects of natural minerals such as quartz or feldspar, due to the competing effects of charge trapping due to the natural radioactivity within the rock and charge detrapping due to thermal loss during rock exhumation towards the surface. We collected 9 samples along the Waiho valley (crossing the Alpine Fault) and the Franz Josef glacier to quantify late-Quaternary exhumation rates and their potential spatial variations. Bedrock samples have been crushed to extract the light-safe rock interiors which have then been processed to isolate potassium-rich feldspars (K-feldspars). We used the Infra-Red Stimulated Luminescence at 50°C (IRSL50) protocol, including the measurement of the natural IRSL50 trapped charge population and the laboratory characterization of sample-specific thermal and athermal kinetic parameters. Once measured, the luminescence signal can be inverted into cooling histories. We also explored the potential of the recently developed multi-OSL-thermochronometer (King et al., accepted) to better constrain the cooling path. Our first OSL measurements show that samples are not in saturation and thus contain useful thermochronometric information over the last ~100 kyr. Inverse

  13. Multi-method geo- and thermochronology of glacially transported cobbles reveals the tectonic and exhumation history of the St. Elias Mountains (Alaska/Yukon)

    Science.gov (United States)

    Falkowski, Sarah; Enkelmann, Eva; Drost, Kerstin; Pfänder, Jörg; Stübner, Konstanze; Ehlers, Todd

    2016-04-01

    -ridge subduction and associated formation and cooling of the Chugach Metamorphic Complex, the beginning of flat-slab subduction of the Yakutat microplate in the late Eocene-early Oligocene, the ongoing Yakutat-North American plate collision, and rapid exhumation of the St. Elias syntaxis. For a statistical analysis of erosion and sediment source, however, a higher number of cobbles would be necessary, which is not feasible due to the costly and time-consuming approach. Therefore, the combination of cobble- and sand-sized detritus analysis is recommended.

  14. Exhumation history of the Northern Andes from the Cenozoic syn-tectonic sedimentary fill of the Middle Magdalena Valley Basin, Colombia

    Science.gov (United States)

    Moreno, C. J.; Caballero, V. M.; Horton, B. K.; Mora, A.

    2009-12-01

    The Central Cordillera and the Eastern Cordillera of the northern Andes form the western and eastern flanks of the Colombian Middle Magdalena Valley Basin, respectively. Previous estimates of the timing of onset of exhumation of the two cordilleras vary, and although some recent studies have been in agreement, more work is needed to develop a clear picture. The spatial and chronological distribution of deformation has direct implications for the shortening history of the greater South American Andean margin, as well as for improving predictions of the rapid, lateral facies changes associated with the varying nearby sediment sources. Field-based analyses of the basin fill using paleocurrent measurements of trough-cross-beds, clast imbrication and flute casts, not only provide new insights into the tectonic history, but directly complement recent detrital zircon U-Pb work completed in the MMVB. Between the lower and upper Paleocene strata, the paleocurrent direction shifts from northward to eastward, indicating that uplift of the Central Cordillera was underway by the mid-Paleocene and consistent with the shift from a cratonic to Central Cordilleran sediment source observed in the detrital zircon record. This paleocurrent shift occurs coevally with a shift from delta to fluvial facies. An eastward paleoflow in upper Eocene through lowest Oligocene strata indicate a continuing influence of the Central Cordillera. Paleocurrent directions in the lower Oligocene deposits are highly variable, and, beginning in the middle Oligocene strata, show a switch to a dominantly westward orientation that continues through the Neogene. As the orientation changes, deposits show an increase in energy from muddy, meandering river deposits, to coarser, braided channel facies. We attribute this switch, from eastward to westward paleocurrent orientations, to the onset of exhumation of the Eastern Cordillera. The results of a current, detailed sandstone petrographic study combined with

  15. Putting it all together: Exhumation histories from a formal combination of heat flow and a suite of thermochronometers

    Science.gov (United States)

    d'Alessio, M. A.; Williams, C.F.

    2007-01-01

    A suite of new techniques in thermochronometry allow analysis of the thermal history of a sample over a broad range of temperature sensitivities. New analysis tools must be developed that fully and formally integrate these techniques, allowing a single geologic interpretation of the rate and timing of exhumation and burial events consistent with all data. We integrate a thermal model of burial and exhumation, (U-Th)/He age modeling, and fission track age and length modeling. We then use a genetic algorithm to efficiently explore possible time-exhumation histories of a vertical sample profile (such as a borehole), simultaneously solving for exhumation and burial rates as well as changes in background heat flow. We formally combine all data in a rigorous statistical fashion. By parameterizing the model in terms of exhumation rather than time-temperature paths (as traditionally done in fission track modeling), we can ensure that exhumation histories result in a sedimentary basin whose thickness is consistent with the observed basin, a physically based constraint that eliminates otherwise acceptable thermal histories. We apply the technique to heat flow and thermochronometry data from the 2.1 -km-deep San Andreas Fault Observatory at Depth pilot hole near the San Andreas fault, California. We find that the site experienced <1 km of exhumation or burial since the onset of San Andreas fault activity ???30 Ma.

  16. Late Miocene to present-day exhumation and uplift of the Internal Zone of the Rif chain: Insights from low temperature thermochronometry and basin analysis

    Science.gov (United States)

    Romagny, A.; Ph. Münch; Cornée, J.-J.; Corsini, M.; Azdimousa, A.; Melinte-Dobrinescu, M. C.; Drinia, H.; Bonno, M.; Arnaud, N.; Monié, P.; Quillévéré, F.; Ben Moussa, A.

    2014-07-01

    Located on the margin of the west Alboran basin, the Gibraltar Arc (Betic-Rif mountain belt) displays post-Pliocene vertical movements evidenced by uplifted marine sedimentary basins and marine terraces. Quantification of vertical movements is an important clue to understand the origin of present-day relief generation in the Betic-Rif mountain chain together with the causes of the Messinian Salinity Crisis. In this paper, we present the results of a pluridisciplinary study combining an analysis of low temperature thermochronology and Pliocene basins evolution to constrain the exhumation history and surface uplift of internals units of the Rif belt (Northern Morocco). The mean (U-Th)/He apatite ages obtained from 11 samples are comprised between 14.1 and 17.8 Ma and display a wide dispersion, which could be explained by a great variability of apatite chemistries in the analyzed samples. No correlations between altitude and age have been found along altitudinal profile suggesting a rapid exhumation during this period. Thermal modeling using our (U-Th)/He apatite ages and geochronological data previously obtained in the same area (40Ar/39Ar and K/Ar data on biotite, zircon and apatite fission track) allow us to propose a cooling history. The rocks suffered a rapid cooling at 60-100 °C/Ma between 22.5 and 19 Ma, then cooled to temperatures around 40 °C between 19 and 18 Ma. They were re-heated at around 110 °C between 18 and 15 Ma then rapidly cooled and exhumed to reach the surface temperature at around 13 Ma. The re-heating could be related to a renewal in thrusting and burying of the inner zones. Between 15 and 13 Ma the cooling resumed at a rate of 50 °C/Ma indicating an exhumation rate of 0.8 mm/y considering an average 40 °C/km geothermal gradient. This exhumation may be linked to the extension in the Alboran Sea. Otherwise biostratigraphic and sedimentological analysis of Pliocene basins of the internal Rif provided informations on the more recent events

  17. Assessment of CFD URANS models for buoyancy driven mixing flows based on ROCOM experiments

    International Nuclear Information System (INIS)

    An assessment of STAR-CCM+ Computational Fluid Dynamics (CFD) models of a KONVOI type Reactor Pressure Vessel (RPV) has been performed based on experimental data collected at the ROssendorf COolant Mixing (ROCOM) test facility as part of the OECD-NEA PKL 2 Project. Three different experimental configurations typical of Main Steam Line Break (MSLB) with Loss-Of-Offsite-Power (LOOP) scenarios are investigated (i.e. Test 1.1, 2.1 and 2.2). The transport of the mixing scalar is based on an equivalent thermal model of the isothermal experimental system. The focus of the study is on the modeling of the physical properties and the turbulent heat flux (closure term) needed by the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations. Results show that a standard Constant Turbulent Prandtl number (CTP) and the chosen Variable Turbulent Prandtl number (VTP) models are capable of describing qualitatively and quantitatively well the time-evolution of the temperature field in the core inlet zone (Test 1.1). When large density differences of the coolant are present in the system, the VTP model outperforms the CTP model in predicting the elevation of the thermal stratification line that builds up in the downcomer due to incomplete mixing. Nevertheless, the CTP model performs very well when the density difference is very low (Test 2.1). No significant changes have been observed for Test 2.2 when idealized boundary conditions are used instead of the experimental ones. (author)

  18. CFD simulations of buoyancy driven flow mixing experiments performed at the ROCOM facility

    International Nuclear Information System (INIS)

    Multi-physics approaches are currently developed at Tractebel Engineering (TE) for accurately simulating the complex interaction between neutronics and thermal-hydraulics during asymmetric accidents. One branch of the improvements of the method focuses on the implementation in the coupled codes package of realistic core inlet distributions obtained from CFD results. Two flow mixing tests performed at the ROCOM facility and representative of asymmetric flow conditions are being simulated with the CFD code ANSYS CFX 12.0. The results show that the main mixing phenomena are qualitatively well reproduced, but a quantitative analysis points out an underestimation of the mixing in the simulations. (author)

  19. Surface tension and buoyancy-driven flow in a non-isothermal liquid bridge

    Science.gov (United States)

    Zhang, Yiqiang; Alexander, J. I. D.

    1992-01-01

    The Navier-Stokes-Boussinesq equations governing the transport of momentum, mass and heat in a nonisothermal liquid bridge with a temperature-dependent surface tension are solved using a vorticity-stream-function formulation together with a nonorthogonal coordinate transformation. The equations are discretized using a pseudo-unsteady semi-implicit finite difference scheme and are solved by the ADI method. A Picard-type iteration is adopted which consists of inner and outer iterative processes. The outer iteration is used to update the shape of the free surface. Two schemes have been used for the outer iteration; both use the force balance normal to the free surface as the distinguished boundary condition. The first scheme involves successive approximation by the direct solution of the distinguished boundary condition. The second scheme uses the artificial force imbalance between the fluid pressure, viscous and capillary forces at the free surface which arises when the boundary condition for force balance normal to the surface is not satisfied. This artificial imbalance is then used to change the surface shape until the distinguished boundary condition is satisfied. These schemes have been used to examine a variety of model liquid bridge situations including purely thermocapillary-driven flow situations and mixed thermocapillary- and bouyancy-driven flow.

  20. Experimental Study of Wind-Opposed Buoyancy-Driven Natural Ventilation

    DEFF Research Database (Denmark)

    Andersen, A.; Bjerre, M.; Chen, Z. D.;

    Natural ventilation driven by natural forces, i.e. wind and thermal buoyancy, is an environmentally friendly system for buildings and has been increasingly used around the world in recent years to mitigate the impact on the global environment due to the significant energy consumption by heating...

  1. A study of the effects of macrosegregation and buoyancy-driven flow in binary mixture solidification

    Science.gov (United States)

    Sinha, S. K.; Sundararajan, T.; Garg, V. K.

    1993-01-01

    A generalized anisotropic porous medium approach is developed for modelling the flow, heat and mass transport processes during binary mixture solidification. Transient predictions are obtained using FEM, coupled with an implicit time-marching scheme, for solidification inside a two-dimensional rectangular enclosure. A parametric study focusing attention on the effects of solutal buoyancy and thermal buoyancy is presented. It is observed that three parameters, namely the thermal Rayleigh number, the solutal Rayleigh number, and the relative density change parameter, significantly alter the flow fields in the liquid and the mushy regions. Depending upon the nature of these flow fields, the solute enrichment caused by macrosegregation may occur in the top or the bottom region of the enclosure.

  2. Dispersion and dissolution of a buoyancy driven gas plume in a layered permeable rock

    Science.gov (United States)

    Woods, Andrew W.; Norris, Simon

    2016-04-01

    Using a series of simplified models, we explore the controls on the migration, dispersion and eventual dissolution of a plume of hydrogen gas which may, in principle, rise under buoyancy through a layered permeable rock if released from a Geological Disposal Facility (GDF). We show that the presence of low permeability shale barriers causes the gas to spread laterally as it rises. Averaging over the length scale of the barriers, we use expressions for the Darcy velocity of the gas to describe the dispersion of a tracer and illustrate the effect with a new experiment using a baffled Hele-Shaw cell. While the plume is flowing, a large volume of gas may build up beneath the barriers. If the gas flux subsequently wanes, much of the gas will drain upward through the formation and spread on the upper impermeable boundary of the formation. However, a significant capillary-trapped wake of gas may develop beneath each barrier. Owing to the low solubility of hydrogen in water and assuming relatively slow groundwater flow rates, this trapped hydrogen may require a period of tens to hundreds of thousands of years to dissolve and form a cloud of hydrogen rich water. Although simplified, these models provide a framework to assess the possible travel times and pathways of such a gas plume.

  3. Disentangle plume-induced anisotropy in the velocity field in buoyancy-driven turbulence

    CERN Document Server

    Zhou, Quan

    2011-01-01

    We present a method of disentangling the anisotropies produced by the cliff structures in turbulent velocity field and test it in the system of turbulent Rayleigh-B\\'{e}nard (RB) convection. It is found that in the RB system the cliff structures in the velocity field are generated by thermal plumes. These cliff structures induce asymmetry in the velocity increments, which leads us to consider the plus and minus velocity structure functions (VSF). The plus velocity increments exclude cliff structures, while the minus ones include them. Our results show that the scaling exponents of the plus VSFs are in excellent agreement with those predicted for homogeneous and isotropic turbulence (HIT), whereas those of the minus VSFs exhibit significant deviations from HIT expectations in places where thermal plumes abound. These results demonstrate that plus and minus VSFs can be used to quantitatively study the effect of cliff structures in the velocity field and to effectively disentangle the associated anisotropies cau...

  4. Buoyancy-driven leakage of oil from a ruptured submarine pipeline

    NARCIS (Netherlands)

    Kranenburg, C.

    1983-01-01

    The rupture of a submarine oil pipeline starts various mechanisms leading to an oil spill. Among these mechanisms the leakage of oil driven by the difference in specific gravities of oil and sea-water is difficult to estimate. A simple mathematical model has been developed and laboratory experiments

  5. Multidisciplinary design approach and safety analysis of ADSR cooled by buoyancy driven flows

    NARCIS (Netherlands)

    Ceballos Castillo, C.A.

    2007-01-01

    Transmutation is useful to reduce the storing time and the amount of nuclear waste to be stored in the geological repository. Transmutation can be achieved in all types of reactors: thermal systems, fast systems, critical and subcritical systems. Fast spectrum systems have significant advantages bec

  6. Large-scale simulations of buoyancy-driven turbulent nuclear burning

    International Nuclear Information System (INIS)

    An critical uncertainty in modeling thermonuclear supernovae is the degree of enhancement of the burning rate by turbulence during the subsonic burning (deflagration) phase. As turbulent combustion in the laboratory is still an active area of research, this remains a challenging problem. A unique feature of turbulent combustion in supernovae is that the driving of the turbulence arises from the strong buoyancy of the burned material. We discuss the large-scale fully three dimensional studies under way. These studies have the goals of characterizing the essential length scales of flame surface structure and thereby developing specific requirements that models of small-scale structure must meet. We discuss some preliminary results of our study concerning the scale-dependence of flame surface structure

  7. Numerical analysis of two and three dimensional buoyancy driven water-exit of a circular cylinder

    Directory of Open Access Journals (Sweden)

    Moshari Shahab

    2014-06-01

    Full Text Available With the development of the technology of underwater moving bodies, the need for developing the knowledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free surface deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an external force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simulation errors of present work (using VOF method for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.

  8. Buoyancy-driven flow in a peat moss layer as a mechanism for solute transport

    NARCIS (Netherlands)

    Rappoldt, C.; Pieters, G.J.J.M.; Adema, E.B.; Baaijens, G.J.; Grootjans, A.P.; Duijn, van C.J.

    2003-01-01

    Transport of nutrients, CO2, methane, and oxygen plays an important ecological role at the surface of wetland ecosystems. A possibly important transport mechanism in a water-saturated peat moss layer (usually Sphagnum cuspidatum) is nocturnal buoyancy flow, the downward flow of relatively cold surfa

  9. Buoyancy-driven convection and mixing in magma chambers - the case of Phlegraean Fields caldera

    Science.gov (United States)

    Montagna, Chiara P.; Longo, Antonella; Bagagli, Matteo; Papale, Paolo

    2016-04-01

    Ascent of primitive magmas from depth into shallow, partially degassed reservoirs is commonly assumed to be a viable eruption trigger. At Phlegraean Fields (Southern Italy), processes of convection and mixing have been identified as taking an active part both in pre- and syn-eruptive stages in many eruptions of different size. We performed numerical simulations of magma chamber replenishment referring to an archetypal case whereby a shallow, small magma chamber containing degassed phonolite is invaded by volatile-rich shoshonitic magma coming from a deeper, larger reservoir. The system evolution is solely driven by buoyancy, as the magma entering the shallower chamber is less dense than the degassed, resident phonolite. The evolution in space and time of physical quantities such as pressure, gas content and density is highly heterogeneous; nonetheless, an overall decreasing exponential trend in time can be observed and characterizes the whole process. The same exponentially decreasing trend can be observed in the amplitude of the ground deformation signals (seismicity over the whole frequency spectrum) calculated from the results of the magmatic dynamics. Exponential decay in the efficiency of the mixing process has been also observed experimentally, albeit on much smaller length and time scales (Morgavi et al., Contrib. Min. Petr. 2013). Depending on the initial and boundary conditions explored, such as chamber geometry or density contrast, the time constant thus the duration of the process can vary. Independently, the evolution of pressure in the magmatic system also depends on the initial and boundary conditions, leading either to eruption-favourable conditions or not. Relating the time scales for convective processes to be effective with their outcomes in terms of stresses at the chamber boundaries can substantially improve our ability to forecast eruptions at volcanoes worldwide.

  10. Modeling the buoyancy-driven Black Sea Water outflow into the North Aegean Sea

    Directory of Open Access Journals (Sweden)

    Nikolaos Kokkos

    2016-04-01

    Full Text Available A three-dimensional numerical model was applied to simulate the Black Sea Water (BSW outflux and spreading over the North Aegean Sea, and its impact on circulation and stratification–mixing dynamics. Model results were validated against satellite-derived sea surface temperature and in-situ temperature and salinity profiles. Further, the model results were post-processed in terms of the potential energy anomaly, ϕ, analyzing the factors contributing to its change. It occurs that BSW contributes significantly on the Thracian Sea water column stratification, but its signal reduces in the rest of the North Aegean Sea. The BSW buoyancy flux contributed to the change of ϕ in the Thracian Sea by 1.23 × 10−3 W m−3 in the winter and 7.9 × 10−4 W m−3 in the summer, significantly higher than the corresponding solar heat flux contribution (1.41 × 10−5 W m−3 and 7.4 × 10−5 W m−3, respectively. Quantification of the ϕ-advective term crossing the north-western BSW branch (to the north of Lemnos Island, depicted a strong non-linear relation to the relative vorticity of Samothraki Anticyclone. Similar analysis for the south-western branch illustrated a relationship between the ϕ-advective term sign and the relative vorticity in the Sporades system. The ϕ-mixing term increases its significance under strong winds (>15 m s−1, tending to destroy surface meso-scale eddies.

  11. Particle fluid interactivity deteriorates buoyancy driven thermal transport in nanosuspensions : A multi component lattice Boltzmann approach

    CERN Document Server

    S, Savithiri; Pattamatta, Arvind; Das, Sarit K

    2015-01-01

    Severe contradictions exist between experimental observations and computational predictions regarding natural convective thermal transport in nanosuspensions. The approach treating nanosuspensions as homogeneous fluids in computations has been pin pointed as the major contributor to such contradictions. To fill the void, inter particle and particle fluid interactivities (slip mechanisms), in addition to effective thermophysical properties, have been incorporated within the present formulation. Through thorough scaling analysis, the dominant slip mechanisms have been identified. A Multi Component Lattice Boltzmann Model (MCLBM) approach has been proposed, wherein the suspension has been treated as a non homogeneous twin component mixture with the governing slip mechanisms incorporated. The computations based on the mathematical model can accurately predict and quantify natural convection thermal transport in nanosuspensions. The role of slip mechanisms such as Brownian diffusion, thermophoresis, drag, Saffman ...

  12. Volcanosedimentary Basins in the Arabian-Nubian Shield: Markers of Repeated Exhumation and Denudation in a Neoproterozoic Accretionary Orogen

    Directory of Open Access Journals (Sweden)

    Victoria Pease

    2013-07-01

    Full Text Available The Arabian-Nubian Shield (ANS includes Middle Cryogenian-Ediacaran (790–560 Ma sedimentary and volcanic terrestrial and shallow-marine successions unconformable on juvenile Cryogenian crust. The oldest were deposited after 780–760 Ma shearing and suturing in the central ANS. Middle Cryogenian basins are associated with ~700 Ma suturing in the northern ANS. Late Cryogenian basins overlapped with and followed 680–640 Ma Nabitah orogenesis in the eastern ANS. Ediacaran successions are found in pull-apart and other types of basins formed in a transpressive setting associated with E-W shortening, NW-trending shearing, and northerly extension during final amalgamation of the ANS. Erosion surfaces truncating metamorphosed arc rocks at the base of these successions are evidence of periodic exhumation and erosion of the evolving ANS crust. The basins are evidence of subsequent subsidence to the base level of alluvial systems or below sea level. Mountains were dissected by valley systems, yet relief was locally low enough to allow for seaways connected to the surrounding Mozambique Ocean. The volcanosedimentary basins of the ANS are excellently exposed and preserved, and form a world-class natural laboratory for testing concepts about crustal growth during the Neoproterozoic and for the acquisition of data to calibrate chemical and isotopic changes, at a time in geologic history that included some of the most important, rapid, and enigmatic changes to Earth’s environment and biota.

  13. Fission track ages and Exhumation mechanisms of the Tauern Window, Eastern Alps

    Science.gov (United States)

    Bertrand, Audrey; Rosenberg, Claudio; Garcia, Sebastian

    2010-05-01

    The Tauern Window (TW) is a thermal and structural dome which exposes Penninic basement, its cover units as well as parts of the overlying Austroalpine basement in the central part of the Eastern Alps. The peak of metamorphism was attained approximately at 30Ma (Selverstone et .al, 1992), followed by cooling and exhumation throughout Miocene time. Most of the tertiary exhumation of the Eastern Alps was localized in the TW, from Early Oligocene to late Miocene time. A current debate centers on the exhumation mechanisms of Penninic rocks in the core of the TW, namely to assess whether orogen-parallel extension (e.g., Selverstone, 1988) or a combination of folding and erosion (eg., Rosenberg et al., 2004) with subordinate extension were the controlling processes. E-W extension is well documented at the western (Brenner Fault) and eastern (Katschberg Fault) margins of the window (e.g., Behrmann, 1988; Selverstone, 1988; Genser and Neubauer, 1989). In contrast, upright folding dominates the internal structure of the dome, and in particular along its western part, where fold amplitudes, mostly eroded during folding, attained up to 10 km. This study attempts to assess the relative importance of folding and erosion and of orogen-parallel extension during exhumation by analyzing the spatial and temporal cooling patterns of apatite and zircon fission track ages. The compilation of published apatite and zircon fission track ages indicates a concentric younging of both the apatite and zircon ages toward the core of the TW. The concentric isochrones follow the map trace of the axial planes of the upright folds of the western and eastern TW. This cooling pattern is in contrast to the one expected by a process of extensional unroofing, which in map view would results in isochrons parallel to the extensional faults and progressively younging towards them (e.g., Foster et al., 2001). We therefore propose that folding and erosion were primarily responsible for exhuming the Penninic

  14. Exhumation history of the NW Indian Himalaya revealed by fission track and 40Ar/39Ar ages

    Science.gov (United States)

    Schlup, Micha; Steck, Albrecht; Carter, Andrew; Cosca, Michael; Epard, Jean-Luc; Hunziker, Johannes

    2011-01-01

    New fission track and Ar/Ar geochronological data provide time constraints on the exhumation history of the Himalayan nappes in the Mandi (Beas valley) — Tso Morari transect of the NW Indian Himalaya. Results from this and previous studies suggest that the SW-directed North Himalayan nappes were emplaced by detachment from the underthrusted upper Indian crust by 55 Ma and metamorphosed by ca. 48–40 Ma. The nappe stack was subsequently exhumed to shallow upper crustal depths (

  15. BURIAL AND EXHUMATION OF THE TERRA NOVA BAY REGION, TRANSANTARCTIC MOUNTAINS

    OpenAIRE

    Prenzel, Jannis

    2014-01-01

    This thesis focuses on the Terra Nova Bay region in the Ross Sea sector of the Transantarctic Mountains. For quantification of the burial and exhumation history, thermochronological methods were applied on samples from vertical profiles across the basement in the northern Terra Nova Bay region (Eisenhower Range, Deep Freeze Range) and supplemented by paleotemperature analysis on overlying Beacon sandstones from the Eisenhower Range and published thermochronological data of vertical basement p...

  16. Ancestral Rocky Mountian Tectonics: A Sedimentary Record of Ancestral Front Range and Uncompahgre Exhumation

    Science.gov (United States)

    Smith, T. M.; Saylor, J. E.; Lapen, T. J.

    2015-12-01

    The Ancestral Rocky Mountains (ARM) encompass multiple crustal provinces with characteristic crystallization ages across the central and western US. Two driving mechanisms have been proposed to explain ARM deformation. (1) Ouachita-Marathon collision SE of the ARM uplifts has been linked to an E-to-W sequence of uplift and is consistent with proposed disruption of a larger Paradox-Central Colorado Trough Basin by exhumation of the Uncompahgre Uplift. Initial exhumation of the Amarillo-Wichita Uplift to the east would provide a unique ~530 Ma signal absent from source areas to the SW, and result in initial exhumation of the Ancestral Front Range. (2) Alternatively, deformation due to flat slab subduction along a hypothesized plate boundary to the SW suggests a SW-to-NE younging of exhumation. This hypothesis suggests a SW-derived Grenville signature, and would trigger uplift of the Uncompahgre first. We analyzed depositional environments, sediment dispersal patterns, and sediment and basement zircon U-Pb and (U-Th)/He ages in 3 locations in the Paradox Basin and Central Colorado Trough (CCT). The Paradox Basin exhibits an up-section transition in fluvial style that suggests a decrease in overbank stability and increased lateral migration. Similarly, the CCT records a long-term progradation of depositional environments from marginal marine to fluvial, indicating that sediment supply in both basins outpaced accommodation. Preliminary provenance results indicate little to no input from the Amarillo-Wichita uplift in either basin despite uniformly westward sediment dispersal systems in both basins. Results also show that the Uncompahgre Uplift was the source for sediment throughout Paradox Basin deposition. These observations are inconsistent with the predictions of scenario 1 above. Rather, they suggest either a synchronous response to tectonic stress across the ARM provinces or an SW-to-NE pattern of deformation.

  17. Post-orogenic exhumation history of a Variscan mid-crustal basement in Galicia (NW Spain)

    Science.gov (United States)

    Grobe, Rene; Alvarez-Marrón, Joaquina; Glasmacher, Ulrich A.; Stuart, Finlay; Castañeda-Zarauz, A.

    2010-05-01

    The present study aims to quantify the complex post-orogenic history of cooling, denudation, and long-term landscape evolution of a mid-crustal section of Variscan basement in Galicia (NW Spain). We use apatite fission-track and apatite (U-Th)/He thermochronological techniques combined with time-temperature (t-T) path modelling using the software code HeFTy©. The topography is characterized by an extensive, low relief area at ~500 m elevation in central Galicia, and a WNW-ESE ridge that reaches up to 1000 m to the North. The area experienced two major tectonic events since the end of the Variscan orogeny in the Late Palaeozoic: 1) continental break-up and Mesozoic rifting leading to the opening of the Atlantic Ocean and the Bay of Biscay, and 2) limited convergence between Iberia and Eurasia since Middle Eocene times. Apatite fission-track ages range from 68.1 ± 5.0 Ma to 174.5 ± 7.7 Ma and apatite (U-Th)/He ages range from 73.6 ± 5.4 to 147.1 ± 16.6 Ma. Age-elevation plots and t-T path modelling suggest a tectonothermal evolution with faster exhumation associated to faulting during Mesozoic rifting. In particular, two major fault systems trending WNW-ESE and NNE-SSW, the As Pontes and the Lugo faults respectively separate areas with the fastest exhumation around 115 Ma from areas with overall slow exhumation since 200-150 Ma. A landscape of subdued topography in central Galicia was acquired prior to Eocene convergence. The higher elevation areas along the northern ridge formed since Middle Eocene times due to fault reactivation and minor exhumation occurred along the fault escarpment.

  18. Uplift, exhumation and erosion along the Angolan continental margin: an integrated approach

    Science.gov (United States)

    Gröger, Heike R.; Machado, Vladimir; Di Pinto, Giuseppe

    2013-04-01

    The topographical development along the SW African margin is not exclusively rift-related. In addition to the onset of rifting in the Early Cretaceous, additional Late Cretaceous and Cenozoic events of uplift, exhumation and erosion are discussed. Thermochronology has proven to be a valuable tool to constrain phases of exhumation in passive continental margins. For South Africa and Namibia a large number of thermochronological data are available. Angola on the other hand is still scarcely investigated. This study is based on thermochronological data from onshore Angola, integrated with quantitative morphotectonic analysis and the on- and offshore stratigraphic record. In South Africa and Namibia published thermochronological data document pronounced Early and Late Cretaceous cooling events, which can be related to 2.5-3.5 km of removed section during the Cretaceous. An additional 1-2 km of removed section are estimated during the Cenozoic. In Angola predominantly Permo-Triassic apatite fission track ages indicate significantly less Cretaceous to Cenozoic erosion (appear directly linked. Cenozoic erosion onshore is mirrored by enhanced Oligocene to Miocene sedimentation offshore. The geomorphological information as well as the stratigraphic record are compatible with the Cenozoic cooling and exhumation as suggested by thermal modelling of apatite fission track data. Although direct indicators for Cretaceous cooling and erosion are missing in Angola, minor amounts of Cretaceous erosion may be disguised by the Miocene final event.

  19. Trace-element record in zircons during exhumation from UHP conditions, North-East Greenland Caledonides

    Science.gov (United States)

    McClelland, W.C.; Gilotti, J.A.; Mazdab, F.K.; Wooden, J.L.

    2009-01-01

    Coesite-bearing zircon formed at ultrahigh-pressure (UHP) conditions share general characteristics of eclogite-facies zircon with trace-element signatures characterized by depleted heavy rare earth elements (HREE), lack of an Eu anomaly, and low Th/ U ratios. Trace-element signatures of zircons from the Caledonian UHP terrane in North-East Greenland were used to examine the possible changes in signature with age during exhumation. Collection and interpretation of age and trace-element analyses of zircon from three samples of quartzofeldspathic gneiss and two leucocratic intrusions were guided by core vs. rim zoning patterns as imaged by cathodoluminesence. Change from igneous to eclogite-facies metamorphic trace-element signature in protolith zircon is characterized by gradual depletion of HREE, whereas newly formed metamorphic rims have flat HREE patterns and REE concentrations that are distinct from the recrystallized inherited cores. The signature associated with eclogite-facies metamorphic zircon is observed in coesite-bearing zircon formed at 358 ?? 4 Ma, metamorphic rims formed at 348 ?? 5 Ma during the initial stages of exhumation, and metamorphic rims formed at 337 ?? 5 Ma. Zircons from a garnet-bearing granite emplaced in the neck of an eclogite boudin and a leucocratic dike that cross-cuts amphibolite-facies structural fabrics have steeply sloping HREE patterns, variably developed negative Eu anomalies, and low Th/U ratios. The granite records initial decompression melting and exhumation at 347 ?? 2 Ma and later zircon rim growth at 329 ?? 5. The leucocratic dike was likely emplaced at amphibolite-facies conditions at 330 ?? 2 Ma, but records additional growth of compositionally similar zircon at 321 ??2 Ma. The difference between the trace-element signature of metamorphic zircon in the gneisses and in part coeval leucocratic intrusions indicates that the zircon signature varies as a function of lithology and context, thus enhancing its ability to aid in

  20. Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U-Pb and 40Ar-39Ar geochronology

    Science.gov (United States)

    Pereira, M. Francisco; Chichorro, Martim; Silva, J. Brandão; Ordóñez-Casado, Berta; Lee, James K. W.; Williams, Ian S.

    2012-08-01

    New U-Pb and 40Ar-39Ar geochronology and structural data from high- to medium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U-Pb age of 465 ± 14 Ma (Middle Ordovician) measured on migmatite from the Coimbra-Cordoba shear zone is interpreted as the age of protolith crystallization. This age determination revises the information contained in the geological map of Portugal, in which these rocks were considered to be Proterozoic in age. This paper describes the evolution of Variscan wrench tectonics related to the development of shear zones, exhumation of deep crustal rocks and emplacement of magma in the Ossa-Morena Zone basement. In the Coimbra-Cordoba shear zone (transpressional), migmatites were rapidly exhumed from a depth of 42.5 km to 16.6 km over a period of ca. 10 Ma in the Viséan (ca. 340-330 Ma), indicating oblique slip exhumation rates of 8.5 to 10.6 mm/yr (Campo Maior migmatites) and 3.2 mm/yr (Ouguela gneisses) respectively. In the Évora Massif, the gneisses of the Boa Fé shear zone (transtensional) were exhumed from 18.5 to 7.4 km depth in the period ca. 344-334 Ma (Viséan), with exhumation oblique slip rates of 2.8 to 4.2 mm/yr. At the same time, the Early Carboniferous basins of SW Iberia were filled by turbidites and olistoliths, composed mostly of Devonian rocks. The presence of olistoliths indicates significant tectonic instability during sedimentation with large-scale mass movement, probably in the form of gravity slides. Deformation and metamorphism dated at 356 ± 12 Ma, 321 ± 13 Ma and 322 ± 29 Ma respectively suggests that Variscan wrench movements were active in SW Iberia during the Early Carboniferous for a period of at least 35 Ma.

  1. Collision in the Central Alps: 2. Exhumation of high-pressure fragments

    Science.gov (United States)

    Brouwer, F. M.; Burri, T.; Berger, A.; Engi, M.

    2003-04-01

    In the Central Alps high-pressure metamorphic rocks are confined to but a few tectonic units. In the Adula nappe pressures range from about 12 kbar in the north, to 20 kbar in the south [1]. The Southern Steep Belt (SSB) is a high-strain zone at the contact between rocks deriving from Apulia and Eurasia. The SSB contains a tectonic composite of ortho and paragneisses, with widespread bands and lenses of mafic and ultramafic composition. Many of the mafic fragments are garnet-amphibolites or eclogites, with a highly variable degree of retrogression. Our petrological studies indicate that the HP rocks in the SSB show extensive variation in metamorphic pressure. In mafic fragments, pressures retained by assemblages predating the amphibolite facies overprint range from 8 to 21 kbar, while pressure estimates for some peridotites are >30 kbar. Some HP fragments show evidence of substantial heating during decompression. New Lu-Hf and Sm-Nd geochronology, in conjunction with previously published data, indicates a spread in ages obtained from the high-pressure metamorphic assemblage. Thermal models based on simplified kinematics produce computed PTt histories that resemble those documented in individual HP fragments [2]. The SSB is interpreted to represent an exhumed part of a Tectonic Accretion Channel (TAC, cf. [3]), assembled of numerous, relatively small fragments which reflect a variety of paths. The different residence times and exhumation rates reflect a protracted history of subduction and extrusion, in which the fragments moved independently from their current neighbours. Combination of thermal modelling and field-based studies improve our conceptual thinking on the dynamics of exhumation of high-pressure rocks in a convergent orogen. [1] Heinrich (1986) J. Pet. 27: 123-154 [2] Roselle et al. (2002) Amer. J. Sci. 302: 381-409 [3] Engi et al. (2001) Geology 29: 1143-1146

  2. Influence of paleo-heat flow variations on estimates of exhumation rates

    Science.gov (United States)

    von Hagke, Christoph; Luijendijk, Elco

    2016-04-01

    Deriving exhumation estimates from thermochronological data requires assumptions on the paleo-thermal field of the Earth's crust. Existing thermal models take into account heat transfer by diffusion and advection caused by the movement of the crust and erosion as well as changes in geothermal gradient over time caused by changes in structure or thermal properties of the crust, surface temperature and elevation. However, temperature field of mountain belts and basins may vary not only due to tectonic activity or landscape evolution. We present a high-resolution thermochronology data set from the foreland fold-and-thrust belt of the European Alps that shows substantial variation of cooling rates probably caused by hydrothermal flow in the subsurface in the past. Tectonic blocks with uniform exhumation history show variations in cooling of up to 50°C. In addition, changes in cooling between two different fault blocks show opposite trend than expected by models of their tectonic history. The observed historic changes in paleo-geothermal gradients are equal in magnitude to a present-day thermal anomaly caused by the upward flow of warm fluids in the distal part of the foreland basin. The strong variations in geothermal gradients by fluid flow imply that straightforward interpretation of landscape evolution rates using thermochronology is not possible, unless the thermal effects of fluid flow are taken into account. This is of particular importance to studies where the amount of thermochronology data is limited and local hydrothermal anomalies could easily be interpreted as regional exhumation signals. On the other hand, our findings suggest that thermochronology offers new opportunities to constrain magnitude and timing of paleo-heat flow variations in the upper crust.

  3. Formation Mechanism and Exhumation Processes for HP-UHP Metamorphic Rocks in Dabie Mountains

    Institute of Scientific and Technical Information of China (English)

    Hou Mingjin; Tang Jiafu

    2004-01-01

    The high, ultrahigh pressure metamorphic rocks, widely distributed in Dabie Mountains, were described in terms of the geological setting, the marks of the petrology and the mineralogy of the ultrahigh pressure (UHP) metamorphic rocks. According to the estimated uplifting and denudation of the Dabie Mountains, and to the thermodynamics theory, were assessed the depth and pressure (high pressure autoclave) of the formation setting of the UHP metamorphic rocks. Based on all the information mentioned above, a new explanation is derived from the mechanism of formation and the processes of exhumation of the UHP metamorphic rocks.

  4. The Influence of Localized Glacial Erosion on Exhumation Paths in Accreting Coulomb Wedges: Insights from Particle Velocimetry Analysis of Sandbox Models

    Science.gov (United States)

    Newman, P. J.; Davis, K.; Haq, S. S. B.; Ridgway, K.

    2015-12-01

    Glacial erosion can have an impact on the location and development of faults in mountain belts. The rapid removal and deposition of rock, in some cases, is thought to affect the initiation of slip on older fault structures, or cause the development of new structures within the older part of the wedge. We present cross-sectional data from both erosional and non-erosional sandbox models of Coulomb wedges in order to quantify the impact of localized erosion on the location of and slip on deformational structures, as well as the general path of material through a wedge. To do this, we employ Lagrangian particle tracking velocimetry (PTV) using the open-source Python PTV toolkit trackpy, among a suite of other data analysis tools. We are able to extract robust and reliable sets of particle trajectories from a series of images without the need for predefined markers or marker-beds, instead identifying and tracking natural variations in sand color as individual particles. By comparing the motion of particles in cross-section to the local surface topography over an entire experiment, we determine a high-resolution record of exhumation rates, in addition to simple uplift rates. These comparisons are further informed by the use of high-definition Eulerian particle image velocimetry (PIV), which provides quantitative data about the distribution of deformation and instantaneous material displacements throughout a cross-sectional view of a Coulomb wedge. This allows us to interpret these pathways in relation to the behavior of active structures and general wedge morphology. In our experiments, we observe that localized glacial erosion has an impact on material pathways, in the form of an increased rate of exhumation locally, more vertical trajectories towards surface below the zone of erosion, and reactivation of older structures to maintain force balance within the entire wedge.

  5. Role of Neogene Exhumation and Sedimentation on Critical-Wedge Kinematics in the Zagros Orogenic Belt, Northeastern Iraq, Kurdistan

    Science.gov (United States)

    Koshnaw, R. I.; Horton, B. K.; Stockli, D. F.; Barber, D. E.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The Zagros orogenic belt and foreland basin formed during the Cenozoic Arabia-Eurasia collision, but the precise histories of shortening and sediment accumulation remain ambiguous, especially at the NW extent of the fold-thrust belt in Iraqi Kurdistan. This region is characterized by well-preserved successions of Cenozoic clastic foreland-basin fill and deformed Paleozoic-Mesozoic hinterland bedrock. The study area provides an excellent opportunity to investigate the linkage between orogenic wedge behavior and surface processes of erosion and deposition. The aim of this research is to test whether the Zagros orogenic wedge advanced steadily under critical to supercritical wedge conditions involving in-sequence thrusting with minimal erosion or propagated intermittently under subcritical condition involving out-of-sequence deformation with intense erosion. These endmember modes of mountain building can be assessed by integrating geo/thermochronologic and basin analyses techniques, including apatite (U-Th)/He thermochronology, detrital zircon U-Pb geochronology, stratigraphic synthesis, and seismic interpretations. Preliminary apatite (U-Th)/He data indicate activation of the Main Zagros Fault (MZF) at ~10 Ma with frontal thrusts initiating at ~8 Ma. However, thermochronometric results from the intervening Mountain Front Flexure (MFF), located between the MZF and the frontal thrusts, suggest rapid exhumation at ~6 Ma. These results suggest that the MFF, represented by the thrust-cored Qaradagh anticline, represents a major episode of out-of-sequence deformation. Detrital zircon U-Pb analyses from the Neogene foreland-basin deposits show continuous sediment derivation from sources to the NNE in Iraq and western Iran, suggesting that out-of-sequence thrusting did not significantly alter sedimentary provenance. Rather, intense hinterland erosion and recycling of older foreland-basin fill dominated sediment delivery to the basin. The irregular distribution of

  6. Petrofabrics of High-Pressure Rocks Exhumed at the Slab-Mantle Interface from the 'Point of No Return'

    Science.gov (United States)

    Whitney, D. L.; Teyssier, C. P.; Seaton, N. C.; Fornash, K.

    2014-12-01

    The highest pressure typically recorded by metamorphic rocks exhumed from oceanic subduction zones is ~2.5±1 GPa, corresponding to the maximum decoupling depth (MDD) (80±10 km) identified in active subduction zones; beyond the MDD (the 'point of no return') exhumation is unlikely. One of the few places where rocks returned from the MDD largely unaltered is Sivrihisar, Turkey: a structurally coherent terrane of lawsonite eclogite and blueschist facies rocks in which assemblages and fabrics record P-T-fluid-deformation conditions during exhumation from ~80 to 45 km. Crystallographic fabrics and other structural features of high-pressure metasedimentary and metabasaltic rocks record transitions during exhumation. In quartzite, heterogeneous microstructures and crystallographic fabrics record deformation and dynamic recrystallization from ~2.6 GPa to ~1.5 GPa, as expressed by transition from prism c-axis patterns through progressive overprinting and activation of rhomb and basal slip. Omphacite, glaucophane, phengite, and lawsonite in quartzite remained stable during deformation. In marble, CaCO3 deformed in dislocation creep as aragonite, producing strong crystallographic fabrics. This fabric persisted through formation of calcite and destruction of the shape-preferred orientation, indicating the strength of aragonite marble. Omphacite in metabasalt and quartzite displays an L-type crystallographic fabric. Lawsonite kinematic vorticity data and other fabrics in metabasalt are consistent with exhumation involving increasing amounts of pure shear relative to simple shear and indicate strain localization and simple shear near the fault contact between the high-pressure unit and a serpentinite body. This large coaxial component multiplied the exhuming power of the subduction channel and forced rocks to return from the MDD.

  7. Tales from the grave: Opposing autopsy reports from a body exhumed.

    Science.gov (United States)

    Gunasekera, R S; Brown, A B; Costas, E H

    2012-07-01

    We report an autopsy case of a 42-year-old woman who, when discovered, had been dead in her apartment for approximately 1 week under circumstances involving treachery, assault and possible drug overdose. This case is unique as it involved two autopsies of the deceased by two different medical examiners who reached opposing conclusions. The first autopsy was performed about 10 days after death. The second autopsy was performed after an exhumation approximately 2 years after burial. Evidence collected at the crime scene included blood samples from which DNA was extracted and analysed, fingerprints and clothing containing dried body fluids. The conclusion of the first autopsy was accidental death due to cocaine toxicity; the conclusion of the second autopsy was death due to homicide given the totality of evidence. Suspects 1 and 2 were linked to the death of the victim by physical evidence and suspect 3 was linked by testimony. Suspect 1 received life in prison, and suspects 2 and 3 received 45 and 20 years in prison, respectively. This case indicates that cocaine toxicity is difficult to determine in putrefied tissue and that exhumations can be important in collecting forensic information. It further reveals that the combined findings of medical examiners, even though contradictory, are useful in determining the circumstances leading to death in criminal justice. Thus, this report demonstrates that such criminal circumstances require comparative forensic review and, in such cases, scientific conclusions can be difficult.

  8. Nb-Ta mobility and fractionation during exhumation of UHP eclogite from southwestern Tianshan, China

    Science.gov (United States)

    Zhang, Lijuan; Zhang, Lifei; Lü, Zeng; Bader, Thomas; Chen, Zhenyu

    2016-05-01

    In order to study the behavior of high field strength elements (HFSE) during retrograde overprint of ultrahigh-pressure (UHP) eclogites, analysis of Nb and Ta concentrations was carried out on bulk rock, rutile (in both veins and host rocks) and titanite in the host eclogite. The studied samples were collected from the UHP metamorphic belt of southwestern Tianshan, China. Petrographic observation and phase equilibria modeling show that the host eclogites have experienced UHP metamorphism and the rutile-bearing veins are thought to be originated from an internal fluid source, probably by lawsonite dehydration during exhumation. The presence of vein rutile indicates HFSE could be mobilized from host eclogites to veins, which is probably facilitated by complexation with dissolved Na-Al silicates and fluorine-rich fluids. Changes in fluid composition (e.g., F-1, X(CO2)) may trigger the precipitation of rutile. Rutile/fluid partitioning may be the key to fractionating Nb and Ta, with preference for Ta in the fluid, resulting in Nb/Ta ratio of rutile in the veins lower than that in the host eclogite. Besides, the transformation of rutile into titanite also might be an effective mechanism for fractionating Nb from Ta, resulting in the intra-grain Nb-Ta zonations in vein rutile. The Nb-Ta mobility and fractionation can happen during exhumation of the UHP eclogite, which should be very important for understanding the behavior of HFSE in subduction zone metamorphism.

  9. From nappe stacking to exhumation: Cretaceous tectonics in the Apuseni Mountains (Romania)

    Science.gov (United States)

    Reiser, Martin Kaspar; Schuster, Ralf; Spikings, Richard; Tropper, Peter; Fügenschuh, Bernhard

    2016-05-01

    New Ar-Ar muscovite and Rb-Sr biotite age data in combination with structural analyses from the Apuseni Mountains provide new constraints on the timing and kinematics of deformation during the Cretaceous. Time-temperature paths from the structurally highest basement nappe of the Apuseni Mountains in combination with sedimentary data indicate exhumation and a position close to the surface after the Late Jurassic emplacement of the South Apuseni Ophiolites. Early Cretaceous Ar-Ar muscovite ages from structurally lower parts in the Biharia Nappe System (Dacia Mega-Unit) show cooling from medium-grade conditions. NE-SW-trending stretching lineation and associated kinematic indicators of this deformation phase (D1) are overprinted by top-NW-directed thrusting during D2. An Albian to Turonian age (110-90 Ma) is proposed for the main deformation (D2) that formed the present-day geometry of the nappe stack and led to a pervasive retrograde greenschist-facies overprint. Thermochronological and structural data from the Bihor Unit (Tisza Mega-Unit) allowed to establish E-directed differential exhumation during Early-Late Cretaceous times (D3.1). Brittle detachment faulting (D3.2) and the deposition of syn-extensional sediments indicate general uplift and partial surface exposure during the Late Cretaceous. Brittle conditions persist during the latest Cretaceous compressional overprint (D4).

  10. Kinematics of post-orogenic extension and exhumation of the Taku Schist, NE Peninsular Malaysia

    Science.gov (United States)

    Md Ali, M. A.; Willingshofer, E.; Matenco, L.; Francois, T.; Daanen, T. P.; Ng, T. F.; Taib, N. I.; Shuib, M. K.

    2016-09-01

    Recent studies imply that the formation and evolution of many SE Asian basins was driven by extensional detachments or systems of low-angle normal faults that created significant crustal exhumation in their footwalls. In this context, the architecture of the Triassic Indosinian orogen presently exposed in Peninsular Malaysia is compatible with significant extension post-dating the orogenic event. In this study we performed a kinematic analysis based on fieldwork and microstructural observations in the Taku Schist, Kemahang granite and the surrounding Gua Musang sediments of northern Peninsular Malaysia in order to shed light on processes related to the build-up and subsequent demise of the Indosinian orogen. The first three phases of deformation were related to an overall period of E-W oriented contraction and burial metamorphism. These phases of deformation are characterized by isoclinal folding with flat lying axial plane cleavages (D1), asymmetrical folding, top-to-the-W-SW shearing (D2) and upright folding (D3). All are in general agreement with observations of the previously inferred Permo-Triassic Indosinian orogeny. During these times, the Taku Schist, a sequence of Paleozoic clastic sediments with mafic intercalations was metamorphosed to amphibolite facies. These rocks are most likely equivalent to the ones exposed in the Bentong-Raub suture zone. Structural relations suggest that the Triassic Kemahang pluton is syn-kinematic, which provides important constraints for the timing of these contractional events. We demonstrate that the overall shortening was followed by a hitherto undescribed extension in NW-SE direction resulting in the formation of a large-scale detachment, the Taku detachment, in northern Peninsular Malaysia. Extension probably reactivated the former subduction plane as a detachment and exhumed previously buried and metamorphosed rocks of similar lithological composition to the neighboring Bentong-Raub suture zone. Such a mechanism is

  11. Early Tertiary exhumation of the flank of a forearc basin, southwest Talkeetna Mountains, Alaska

    Science.gov (United States)

    Bleick, Heather A.; Till, Alison B.; Bradley, Dwight C.; O’Sullivan, Paul; Wooden, Joe L.; Bradley, Dan B.; Taylor, Theresa A.; Friedman, Sam B.; Hults, Chad P.

    2012-01-01

    New geochronologic and thermochronologic data from rocks near Hatcher Pass, southwest Talkeetna Mountains, Alaska, record earliest Paleocene erosional and structural exhumation on the flank of the active Cook Inlet forearc basin. Cretaceous plutons shed sediments to the south, forming the Paleocene Arkose Ridge Formation. A Paleocene(?)-Eocene detachment fault juxtaposed ~60 Ma metamorphic rocks with the base of the Arkose Ridge Formation. U-Pb (analyzed by Sensitive High Resolution Ion Micro Probe Reverse Geometry (SHRIMP-RG)) zircon ages of the Cretaceous plutons, more diverse than previously documented, are 90.3±0.3 (previously considered a Jurassic unit), 79.1±1.0, 76.1±0.9, 75.8±0.7, 72.5±0.4, 71.9±0.3, 70.5±0.2, and 67.3±0.2 Ma. The cooling of these plutons occurred between 72 and 66 Ma (zircon fission track (FT) closure ~225°C). 40Ar/39Ar analyses of hornblende, white mica, and biotite fall into this range (Harlan and others, 2003). New apatite FT data collected on a west-to-east transect reveal sequential exhumation of fault blocks at 62.8±2.9, 54±2.5, 52.6±2.8, and 44.4±2.2 Ma. Plutonic clasts accumulated in the Paleocene Arkose Ridge Formation to the south. Detrital zircon (DZ) ages from the formation reflect this provenance: a new sample yielded one grain at 61 Ma, a dominant peak at 76 Ma, and minor peaks at 70, 80, 88, and 92 Ma. The oldest zircon is 181 Ma. Our apatite FT ages range from 35.1 to 50.9 Ma. Greenschist facies rocks now sit structurally between the plutonic rocks and the Arkose Ridge Formation. They are separated from plutonic rocks by the vertical Hatcher Pass fault and from the sedimentary rocks by a detachment fault. Ar cooling ages (Harlan and others, 2003) and new zircon FT ages for these rocks are concordant at 61-57 Ma, synchronous with deposition of the Arkose Ridge Formation. A cooling age of ~46 Ma came from one apatite FT sample. The metamorphic protolith (previously considered Jurassic) was deposited at or after

  12. Deep-tow magnetic survey above large exhumed mantle domains of the eastern Southwest Indian ridge

    Science.gov (United States)

    Bronner, A.; Munschy, M.; Carlut, J. H.; Searle, R. C.; Sauter, D.; Cannat, M.

    2011-12-01

    The recent discovery of a new type of seafloor, the "smooth seafloor", formed with no or very little volcanic activity along the ultra-slow spreading Southwest Indian ridge (SWIR) shows an unexpected complexity in processes of generation of the oceanic lithosphere. There, detachment faulting is thought to be a mechanism for efficient exhumation of deep-seated mantle rocks. We present here a deep-tow geological-geophysical survey over smooth seafloor at the eastern SWIR (62-64°N) combining magnetic data, geology mapping from side-scan sonar images and results from dredge sampling. We introduce a new type of calibration approach for deep-tow fluxgate magnetometer. We show that magnetic data can be corrected from the magnetic effect of the vehicle with no recourse to its attitude (pitch, roll and heading) but only using the 3 components recorded by the magnetometer and an approximation of the scalar intensity of the Earth magnetic field. The collected dredge samples as well as the side-scan images confirm the presence of large areas of exhumed mantle-derived peridodites surrounded by a few volcanic constructions. This allows us to hypothesis that magnetic anomalies are caused by serpentinized peridotites or magmatic intrusions. We show that the magnetic signature of the smooth seafloor is clearly weaker than the surrounding volcanic areas. Moreover, the calculated magnetization of a source layer as well as the comparison between deep-tow and sea-surface magnetic data argue for strong East-West variability in the distribution of the magnetized sources. This variability may results from fluid-rocks interaction along the detachment faults as well as from the repartition of the volcanic material and thus questions the seafloor spreading origin of the corresponding magnetic anomalies. Finally, we provide magnetic arguments, as calculation of block rotation or spreading asymmetry in order to better constrain tectonic mechanisms that occur during the formation of this

  13. New Thermochronologic Data Constraining the Exhumation History of the Pangong Range, Ladakh, NW India

    Science.gov (United States)

    Bohon, W.; Tripathy, A.; Hodges, K.; Arrowsmith, R.; Van Soest, M. C.

    2011-12-01

    Major transcurrent fault systems have played a fundamental role in the late Cenozoic evolution of the Himalayan-Tibetan orogenic system. One of the most dramatic of these is the NW-SE striking, dextral-oblique Karakoram fault system (KFS), which effectively serves as the SW boundary of the Tibetan Plateau. In the Ladakh region of NW India, the fault system bifurcates into 2 fault strands bounding the Pangong Range (PR), a lozenge-shaped region of high elevation that is commonly regarded as a transpressional uplift. We are studying the partitioning of slip over time between shortening and translational components during transpression along both KFS strands. An important aspect of this work is a study of the differential exhumation history of the PR relative to two other high elevation regions to the north and south: the Karakoram Range (KR) and the Ladakh Range (LR), respectively. Although a variety of thermochronometric data will be reported for the LR, PR, and KR in our presentation, we focus here on (U-Th)/He zircon (ZHe) data for the KR and LR. Four published ZHe dates for the northern margin of the LR (Kirstein et al., 2009, Geological Society of London, special pub.) range from 12.9 ± 2.0 Ma to 19.2 ± 3.0 Ma (2 σ) with a rough correlation of older dates at higher elevations. Our new dates for samples collected nearer to the SW strand of the KFS are substantially younger: 7.5 ± 0.12 Ma. It is unclear if the combined datasets are indicative of protracted cooling of the northern part of the LR during rotational exhumation of the LR to the south, as postulated by Kirstein et al., or if the ca. 7.5 Ma dates represent local resetting during KFS activity. Interestingly, detrital ZHe data for modern sands from large catchments that drain the KR range to the north of the NE strand of the KFS indicate cooling of the KR below the nominal bulk closure temperature of the ZHe system (ca. 190C) within a narrow time range of 5.5-7.8 Ma. This range includes the ZHe cooling

  14. Deep-tow geophysical survey above large exhumed mantle domains of the eastern Southwest Indian ridge

    Science.gov (United States)

    Bronner, A.; Munschy, M.; Sauter, D.; Carlut, J.; Searle, R.; Cannat, M.

    2012-04-01

    The recent discovery of a new type of seafloor, the "smooth seafloor", formed with no or very little volcanic activity along the easternmost part of the ultra-slow spreading Southwest Indian ridge (SWIR) shows an unexpected complexity in processes of generation of the oceanic lithosphere. There, detachment faulting is thought to be a mechanism for efficient exhumation of deep-seated mantle rocks. We present here a deep-tow geological-geophysical survey over smooth seafloor at the eastern SWIR (62-64°N) combining multibeam bathymetric data, magnetic data, geology mapping from sidescan sonar (TOBI) images and results from dredge sampling. We introduce a new type of calibration approach for deep-tow fluxgate magnetometer. We show that magnetic data can be corrected from the magnetic effect of the vehicle with no recourse to its attitude (pitch, roll and heading) but only using the 3 components recorded by the magnetometer and an approximation of the scalar intensity of the Earth magnetic field. The collected dredge samples as well as the sidescan sonar images confirm the presence of large areas of exhumed mantle-derived peridodites surrounded by a few volcanic constructions. We investigate the possibility that magnetic anomalies are either caused by serpentinized peridotites and/or magmatic intrusions. We show that the magnetic signature of the smooth seafloor is clearly weaker than the surrounding volcanic areas. Moreover, the calculated magnetization of a source layer as well as the comparison between deep-tow and sea-surface magnetic data argue for strong East-West variability in the distribution of the magnetized sources. This variability may result from fluid-rock interactions along the detachment faults as well as from the occurrence of small sized and thin volcanic patches and thus questions the seafloor spreading origin of the corresponding magnetic anomalies. Finally, we provide magnetic arguments, as calculation of block rotation or spreading asymmetry in

  15. Subduction / exhumation dynamics: Petrochronology in the Glacier-Rafray slice (Western Alps, Italy)

    Science.gov (United States)

    Burn, Marco; Lanari, Pierre; Engi, Martin

    2014-05-01

    allochthons; one would expect these to have entered the subduction zone together with the Piemonte oceanic units. Yet all high-P ages reported for the Piemonte oceanic units are around 40 Ma. We propose that the Glacier-Rafray slice experienced subduction together with Sesia units and may have been juxtaposed on the Piemont-Ligurian-Ocean units during Eocene exhumation. Strain associated with this juxtaposition may have triggered growth of the second allanite. Joint exhumation of the oceanic units and the Glacier-Rafray klippe followed at retrograde T.

  16. New parametric implementation of metamorphic reactions limited by water content, impact on exhumation along detachment faults

    Science.gov (United States)

    Mezri, L.; Le Pourhiet, L.; Wolf, S.; Burov, E.

    2015-11-01

    Metamorphic phase changes have a strong impact on the physical and mechanical properties of rocks including buoyancy (body forces) and rheology (interface forces). As such, they exert important dynamic control on tectonic processes. It is generally assumed that phase changes are mainly controlled by pressure (P) and temperature (T) conditions. Yet, in reality, whatever the PT conditions are, phase changes cannot take place without an adequate amount of the main reactant - water. In present day geodynamic models, the influence of water content is neglected. It is generally assumed that water is always available in quantities sufficient for thermodynamic reactions to take place at minimal Gibbs energy for given P and T conditions and a constant chemical composition. If this assumption was correct, no high-grade metamorphic rocks could to be found on the Earth's surface, since they would be retro-morphed to low-grade state during their exhumation. Indeed, petrologic studies point out that water, as a limiting reactant, is responsible for the lack of retrograde metamorphic reactions observed in the rocks exhumed in typical MCC contexts. In order to study the impact of fluid content on the structure of metamorphic core complexes, we have coupled a geodynamic thermo-mechanical code Flamar with a fluid-transport and water-limited thermodynamic phase transition algorithm. We have introduced a new parameterization of Darcy flow that is able to capture source/sink and transport aspects of fluid transport at the scale of the whole crust with a minimum of complexity. Within this model, phase transitions are controlled by pressure temperature and the local amount of free fluid that comes from both external (meteoric) and local (dehydration) sources. The numerical experiments suggest a strong positive feedback between the asymmetry of the tectonic structures and the depth of penetration of meteoric fluids. In particular, bending-stress distribution in asymmetric detachment zones

  17. Low-temperature exhumation history of Variscan-age rocks in the western Cantabrian Mountains (NW Spain) recorded by apatite fission-track data

    Science.gov (United States)

    Grobe, René W.; Alvarez-Marrón, Joaquina; Glasmacher, Ulrich A.; Menéndez-Duarte, Rosana

    2010-06-01

    This paper presents the first regional study of apatite fission-track (AFT) thermochronology to be undertaken in the western termination of the Cantabrian Mountains (NW Spain). The mountains reach elevations of over 2600 m along the northern coast of Spain and are comprised of a Variscan crustal section uplifted due to Cenozoic shortening along the northern Iberian Plate. The study constrains the pattern and history of exhumation within the Paleozoic bedrock over the past c. 240 Ma. Twenty-one apatite fission-track samples range in age from 246.7 (± 26.9) Ma to 78.1 (± 3.7) Ma, with mean track lengths between 10.4 (± 1.8) µm and 12.4 (± 1.4) µm. Time-temperature path modelling of the data indicates that different rates of continuous cooling took place during the three main tectonic events that affected the area. A rapid cooling event that ended by the Late Jurassic corresponds to topographic decay during unroofing of the Variscan orogen and the break-up of Pangea, and is responsible for the largest amount of exhumation. Westernmost samples cooled coinciding with rifting in the North Atlantic and Bay of Biscay during the Late Jurassic to Early Cretaceous. By about 100-80 Ma most samples had reached, or passed through, the upper boundary of the apatite partial annealing zone, which indicate that regional denudation has not exceeded c. 1.7 km since then, for geothermal gradients ≥ 27 °C/km and a surface temperature of 15 °C. Only three samples next to fault escarpments in the west cooled below 70 °C since 80 Ma, reaching below 65 °C before initiation of incipient subduction along the northern Iberian Margin by 46 Ma. An average cooling rate of ≤ 1 °C/Ma reflects latest denudation as the new mountainous relief developed since then due to shortening and incipient subduction associated with convergence along the northern Iberian Plate. The Cantabrian Mountains are one of the few natural examples of a coastal orogen in a juvenile stage of evolution.

  18. Long-term exhumation of a Palaeoproterozoic orogen and the role of pre-existing heterogeneous thermal crustal properties

    DEFF Research Database (Denmark)

    McGregor, E.D.; Nielsen, S.B.; Stephenson, R.A.;

    2013-01-01

    Abstract: New apatite fission-track data from SE Baffin Island exhibit central ages that range from just under 200 Ma to 440 Ma, and mean track lengths that vary between c. 12 and 13.3 μm. First-order analysis of the data (a plot of central age v. mean track length) reveals an approximate...... is attributed here to differential erosion from a variable initial topography. However, age discontinuities over short distances require other explanations such as faulting and/or unidentified compositional effects. Collectively, these results suggest that the observed data are consistent with a simple...... exhumation scenario where the present-day high topography is a remnant of that created during Palaeoproterozoic orogenies. The new data do not require any recent (Cenozoic) periods of exhumation....

  19. Magnetic signature of large exhumed mantle domains of the Southwest Indian Ridge – results from a deep-tow geophysical survey over 0 to 11 Ma old seafloor

    OpenAIRE

    Bronner, A.; Sauter, D.; Munschy, M.; Carlut, J; Searle, R.; Cannat, M.; Manatschal, G.

    2014-01-01

    We investigate the magnetic signature of ultramafic seafloor in the eastern part of the Southwest Indian Ridge (SWIR). There, detachment faulting, continuous over 11 Myr, exhumed large areas of mantle-derived rocks. These exhumed mantle domains occur in the form of a smooth rounded topography with broad ridges locally covered by a thin highly discontinuous volcanic carapace. We present high-resolution data combining deep-tow magnetics, side-scan sonar images and dredged samp...

  20. Thermal and structural evolution of the East Carpathians in northern Romania : from Cretaceous orogeny to final exhumation during Miocene collision

    OpenAIRE

    Gröger, Heike R.

    2006-01-01

    Combining thermochronological methods with structural field data, this study aims to reconstruct the Tertiary burial and exhumation history of the northeastern part of the Tisza‐ Dacia block during its invasion in the Carpathian embayment and final soft collision with the European margin. Zircon fission track data additionally provide information about the last metamorphic overprint during the Cretaceous. Within the basement units of the northern C...

  1. Plate rotation during continental collision and its relationship with the exhumation of UHP metamorphic terranes: Application to the Norwegian Caledonides

    Science.gov (United States)

    Bottrill, A. D.; van Hunen, J.; Cuthbert, S. J.; Brueckner, H. K.; Allen, M. B.

    2014-05-01

    variation and asynchronous onset of collision during the convergence of continents can significantly affect the burial and exhumation of subducted continental crust. Here we use 3-D numerical models for continental collision to discuss how deep burial and exhumation of high and ultrahigh pressure metamorphic (HP/UHP) rocks are enhanced by diachronous collision and the resulting rotation of the colliding plates. Rotation during collision locally favors eduction, the inversion of the subduction, and may explain the discontinuous distribution of ultra-high pressure (UHP) terranes along collision zones. For example, the terminal (Scandian) collision of Baltica and Laurentia, which formed the Scandinavian Caledonides, resulted in the exhumation of only one large HP/UHP terrane, the Western Gneiss Complex (WGC), near the southern end of the collision zone. Rotation of the subducting Baltica plate during collision may provide an explanation for this distribution. We explore this hypothesis by comparing orthogonal and diachronous collision models and conclude that a diachronous collision can transport continental material up to 60 km deeper, and heat material up to 300°C hotter, than an orthogonal collision. Our diachronous collision model predicts that subducted continental margin material returns to the surface only in the region where collision initiated. The diachronous collision model is consistent with petrological and geochonological observations from the WGC and makes predictions for the general evolution of the Scandinavian Caledonides. We propose the collision between Laurentia and Baltica started at the southern end of the collisional zone, and propagated northward. This asymmetric geometry resulted in the counter clockwise rotation of Baltica with respect to Laurentia, consistent with paleomagnetic data from other studies. Our model may have applications to other orogens with regional UHP terranes, such as the Dabie Shan and Papua New Guinea cases, where block

  2. Lisa K. Perdigao. From Modernist Entombment to Postmodernist Exhumation Dead Bodies in Twentieth-Century American Fiction.

    Directory of Open Access Journals (Sweden)

    Ben Robbins

    2012-04-01

    Full Text Available Lisa K. Perdigao’s monograph titled From Modernist Entombment to Postmodernist Exhumation, seeks to offer a comprehensive study of the corpse as represented in American fiction of the twentieth century. Perdigao explores how novelists from a range of time periods and traditions use dead bodies as a device that is revealing of the wider formal ambitions of narrative. In her introduction, Perdigao sets out the theoretical framework on which her study is based. She draws on poststructuralist the...

  3. Exhumation of high-P marbles of the Samaná Terrane (Northern Hispaniola): Insights from paleostress and microstructural imprints

    Science.gov (United States)

    Fernández, Francisco José; Rodríguez, Indira; Escuder-Viruete, Javier; Pérez-Estaún, Andrés

    2016-08-01

    Paleostress variations and microstructural imprints of a subducted carbonate slab record changes in mechanical strength during its exhumation. The slab studied here forms part of the high-P Samaná Terrane located on the north-eastern margin of the Hispaniola Island. Cold-cathodoluminescence images reveal relict cataclastic fabrics within the highest-pressure marbles of the Punta Balandra and Santa Bárbara Schists structural units, formed in the early stages of exhumation at P-T conditions ca. 2.0 GPa - 500 °C. Cataclastic flow was triggered after a moderate increase of water content (1.2% < w.t. H2O < 1.8%). Accordingly, grain sizes larger than equivalent radius ri = 40 μm preserve distribution of power law type with fractal dimensions D2 = 2.43 in Punta Balandra unit and D2 = 2.72 in Santa Bárbara unit. After cataclastic flow, the stress dropped and grain comminution conducted the marbles to the dissolution-precipitation domain. Then, as exhumation progressed, the effective stress increased and calcite intracrystalline plasticity process dominated. Calcite-twinning incidence and recrystallized grain-size indicate maximum paleostress ca. 350 MPa and mean flow paleostress ≈ 130 MPa. SEM-EBSD analyses show similar weak type-c calcite fabrics in all high-P carbonate units, even though they record different metamorphic P peak. Therefore, intracrystalline plasticity was probably dominant during the development of the final tectonic fabric. Finer grain-size distributions are out of fractal range, with D1 < 1, because of the further superposed deformation. Most of the data are consistent with an initial forced exhumation model of the carbonate slab in a brittle-ductile rheology of the confined plate interface.

  4. Exhumation of the Panama basement complex and basins: Implications for the closure of the Central American seaway

    Science.gov (United States)

    Ramírez, Diego A.; Foster, David A.; Min, Kyoungwon; Montes, Camilo; Cardona, Agustín.; Sadove, Gephen

    2016-05-01

    The emergence of the Central American isthmus occurred episodically from Eocene to Pliocene time and was caused by a series of tectonic and volcanic processes. Results from zircon U-Pb geochronology, zircon (U-Th)/He (ZHe) and apatite (U-Th)/He (AHe) thermochronology, and zircon Lu-Hf isotopic data from sedimentary (sandstones and recent river sands) and plutonic rocks from the Azuero Peninsula and Central Panama document the exhumation and uplift history of the Panamanian basement complex. Our data support previous paleobotanical and thermochronological studies that suggest that by middle Eocene time some areas of Central Panama and Azuero Peninsula were exposed above sea level as a series of islands surrounded by shallow open marine waters. The Gatuncillo, Cobachón and Tonosí formations were deposited during this partial emergence. Transtension in the Oligocene-early Miocene produced various pull-apart basins (e.g., the Canal Basin) and local uplift that exhumed the Eocene strata (Gatuncillo and Cobachón formations). This event probably reduced circulation between the Pacific Ocean and the Caribbean Sea. The Tonosí Formation records late Miocene to Pleistocene cooling and exhumation, which may be related to uplift above the subducting Coiba Ridge. These results suggest that the emergence of the Isthmus of Panama followed a series of diachronous events that led to the final closure of the Central American seaway.

  5. Exhumation research concerning the victims of political repressions in 1945-1956 in Poland: A new direction in forensic medicine.

    Science.gov (United States)

    Szleszkowski, Lukasz; Thannhäuser, Agata; Szwagrzyk, Krzysztof; Konczewski, Paweł; Kawecki, Jerzy; Swiątek, Barbara

    2014-02-01

    In 2011 in Wroclaw (Poland), the bodies of 223 prisoners were exhumed, including the victims of political repressions and prosecutions in the period 1949-1954, during which people fighting for the independence of Poland were executed and buried in unidentified graves in various graveyards. It was the first exhumation conducted in Poland on such a large scale. The aim of the present publication is to describe the new direction in forensic medicine employed in these exhumations, which resulted from the new opportunities created by the opening of the state archives after the political transformation of 1989. The authors describe the difficulties they encountered during their exploration of prisoners' burial grounds. The graveyards included in the investigation bear the marks of an intentional policy of confusion and secret burial methods. First, significant disorder in the logical (based on time of death) sequence of burials was observed. This made identification difficult. A substantial time lapse between death and burial in each case, along with the unavailability of comparative data, limited the use of identification methods widely employed in forensic medicine. For this reason, initial analysis had to be based on observations and confirmations made by forensic medicine about the sequence of burials as compared to cemetery documentation. Situations such as this clearly call for the cooperation of historians, archaeologists, anthropologists and forensic pathologists. Political transformations in Eastern Europe in the 1990s gave rise to hopes of exchanging experiences in this type of research as conducted in other countries of the former Eastern Bloc.

  6. Modelling of low-temperature exhumation rate in Dabie Mountain based on (U-Th)/He and fission-track thermochronological data

    Institute of Scientific and Technical Information of China (English)

    DING; Ruxin; ZHOU; Zuyi; XU; Changhai; LIU; Yuzhu; CHENG; Hao; XU; Fei

    2006-01-01

    While the high-temperature exhumation process in the Dabie Mountain has been well documented, the low-temperature exhumation of this area since Cretaceous, especially since Late Cretaceous, is relatively less studied. Low-temperature thermochronology provides one of the important approaches to solve this problem. Based on the data of fission track and (U-Th)/He analysis of apaptites and zircons from the granitoid and metamorphic rocks in the Dabie Mountain, this paper applies Mancktelow's and Braun's methods to estimating the exhumation rates and to drawing the regional differential exhumation pattern since Cretaceous, especially since Late Cretaceous by taking into consideration factors such as heat transport, heat advection, topography and heat production,which could influence geothermal field in the shallow crust. Since Cretaceous, the exhumation rate (0.08-0.10 km/Ma) in the region around Tiantangzhai and in the south of Tanlu fault zone is larger than the rate (0.04-0.07 km/Ma) in other areas of the Dabie Mountain. The regional differential exhumation pattern might be related to the push-up effect caused by differential strike-slip movement along NNE-trending faults.

  7. Structural control of weathering processes within exhumed granitoids: Compartmentalisation of geophysical properties by faults and fractures

    Science.gov (United States)

    Place, J.; Géraud, Y.; Diraison, M.; Herquel, G.; Edel, J.-B.; Bano, M.; Le Garzic, E.; Walter, B.

    2016-03-01

    In the latter stages of exhumation processes, rocks undergo weathering. Weathering halos have been described in the vicinity of structures such as faults, veins or dykes, with a lateral size gradually narrowing with depth, symmetrically around the structures. In this paper, we describe the geophysical characterisation of such alteration patterns on two granitoid outcrops of the Catalan Coastal Ranges (Spain), each of which is affected by one major fault, as well as minor faults and fractures. Seismic, electric and ground penetrating radar surveys were carried out to map the spatial distribution of P-wave velocity, electrical resistivity and to identify reflectors of electromagnetic waves. The analysis of this multi-method and complementary dataset revealed that, at shallow depth, geophysical properties of the materials are compartmentalised and asymmetric with respect to major and subsidiary faults affecting the rock mass. This compartmentalisation and asymmetry both tend to attenuate with depth, whereas the effect of weathering is more symmetric with respect to the major structure of the outcrops. We interpret such compartmentalisation as resulting from the role of hydraulic and mechanical boundaries played by subsidiary faults, which tend to govern both the chemical and physical alterations involved in weathering. Thus, the smoothly narrowing halo model is not always accurate, as weathering halos can be strongly asymmetrical and present highly irregular contours delimiting sharp contrasts of geophysical properties. These results should be considered when investigating and modelling fluid storage and transfer in top crystalline rock settings for groundwater applications, hydrocarbon or geothermal reservoirs, as well as mineral deposits.

  8. In search of the Boston Strangler: genetic evidence from the exhumation of Mary Sullivan.

    Science.gov (United States)

    Foran, David R; Starrs, James E

    2004-01-01

    The Boston Strangler was one of the United States' most notorious serial killers, raping and strangling with decorative ligatures thirteen woman in Boston during the early 1960s. Albert DeSalvo, never a suspect in the slayings, confessed in prison (where he was later murdered) to being the Boston Strangler, and the investigation largely ended. Mary Sullivan was the last victim of the Boston Strangler, found sexually assaulted and strangled in her Boston apartment in 1964. Recently, a team of forensic scientists undertook the exhumation and subsequent scientific analysis of Mary Sullivan's remains, in hope of finding consistencies or inconsistencies between DeSalvo's confessed description of the murder and any evidence left behind. Included in these analyses was extensive DNA testing of all UV fluorescent material associated with the body. The large majority of results were negative, however, fluorescent material located on the underwear and entwined in her pubic hair generated two human mitochondrial DNA sequences. Neither of these matched the victim nor members of the forensic team who worked on the evidence. Most importantly, neither DNA sequence could have originated from Albert DeSalvo.

  9. Strain localization in shear zones during exhumation: a graphical approach to facies interpretation

    Science.gov (United States)

    Cardello, Giovanni Luca; Augier, Romain; Laurent, Valentin; Roche, Vincent; Jolivet, Laurent

    2015-04-01

    Strain localization is a fundamental process determining plate tectonics. It is expressed in the ductile field by shear zones where strain concentrates. Despite their worldwide distribution in most metamorphic units, their detailed characterization and processes comprehension are far to be fully addressed. In this work, a graphic approach to tectono-metamorphic facies identification is applied to the Delfini Shear Zone in Syros (Cyclades, Greece), which is mostly characterized by metabasites displaying different degree of retrogression from fresh eclogite to prasinite. Several exhumation mechanisms brought them from the depths of the subduction zone to the surface, from syn-orogenic exhumation to post-orogenic backarc extension. Boudinage, grain-size reduction and metamorphic reactions determinate strain localization across well-deformed volumes of rocks organized in a hierarchic frame of smaller individual shear zones (10-25 meters thick). The most representative of them can be subdivided in 5 tectono-metamorphic (Tm) facies, TmA to E. TmA records HP witnesses and older folding stages preserved within large boudins as large as 1-2 m across. TmB is characterized by much smaller and progressively more asymmetric boudins and sigmoids. TmC is defined by well-transposed sub- to plane-parallel blueschist textures crossed by chlorite-shear bands bounding the newly formed boudins. When strain increases (facies TmD-E), the texture is progressively retrograded to LP-HT greenschist-facies conditions. Those observations allowed us to establish a sequence of stages of strain localization. The first stage (1) is determined by quite symmetric folding and boudinage. In a second stage (2), grain-size reduction is associated with dense shear bands formation along previously formed glaucophane and quartz-rich veins. With progressively more localized strain, mode-I veins may arrange as tension gashes that gradually evolve to blueschist shear bands. This process determinates the

  10. Mantle exhumation at the Southwest Indian Ridge; preliminary results of the SMOOTHSEAFLOOR cruise

    Science.gov (United States)

    Sauter, D.; Cannat, M.; Andreani, M.; Birot, D.; Bronner, A.; Brunelli, D.; Carlut, J. H.; Delacour, A.; Guyader, V.; Mendel, V.; Ménez, B.; MacLeod, C. J.; Pasini, V.; Rouméjon, S.; Ruellan, E.; Searle, R. C.

    2011-12-01

    The eastern Southwest Indian Ridge (SWIR) is among the deepest part of the oceanic ridge system, and it is thus inferred to represent a melt-poor end-member for this system. It displays the widest expanses known to date of seafloor with no evidence for a volcanic upper crustal layer. This nonvolcanic ocean floor has no equivalent at faster spreading ridges and has been called "smooth seafloor" because it occurs in the form of broad ridges up to 2000 m high with a smooth, rounded topography with no resolvable volcanic cones on bathymetric data (Cannat et al., 2006). On R/V Marion Dufresne cruise "SMOOTHSEAFLOOR" in October 2010, we conducted a detailed geological-geophysical survey of such smooth seafloor areas, determining the rock types exposed at these ridges, searching for hydrothermal activity and mapping the volcanic, tectonic and sedimentary structures. 35 dredges and 15 CTDs have been realized and more than 1000 km long TOBI sidescan sonar images and deep towed magnetometer profiles have been collected over two contrasting survey areas up to magnetic anomaly C5n (10 Ma). The main result of our cruise is that serpentinized mantle-derived peridotites were dredged widely throughout the smooth seafloor areas while gabbros and basalts were rare. Mantle rocks were found on moderate slopes (20-35°), facing toward and away from the axial valley, at ridges with symmetric shape, as well as on gentle slopes (<15°) facing the axis at asymmetric ridges whose outward facing steeper slopes may be covered with volcanics. TOBI sidescan sonar images show that these hillsides are ancient large low angle normal faults which were covered locally by small amount of volcanics and dismembered by landslide activity. These results show that mantle exhumation has been the main process which shaped the smooth seafloor areas of the eastern SWIR for the last 10 Myrs.

  11. Exploring the Variability of Late Cenozoic Exhumation Rates across the Himalayan Rain Shadow

    Science.gov (United States)

    Schultz, M.; Hodges, K. V.; Ehlers, T. A.; Van Soest, M. C.; Wartho, J. A.; McDonald, C.

    2015-12-01

    The Himalayan ranges of South Asia form one of the world's most impressive rain shadows. Data from the NASA - Japan Aerospace Exploration Agency Tropical Rainfall Measurement Mission (TRMM) suggest that precipitation in the central Himalaya drops from more than four meters per year along the southern flanks of the Higher Himalaya (falling mostly as rain during the summer monsoon) to about half a meter per year north of the range crest on the southern Tibetan Plateau. While a correlation between modern precipitation and erosion seems intuitive, important questions remain regarding how far backward in time the correlation might extend. Previous investigations of the relationships between precipitation patterns and thermochronologic cooling dates south of the Himalayan range crest have yielded discrepant results, partly due to the fact that many were conducted along deep trans-Himalayan gorges that serve to channel monsoon storms locally northward, sometimes obscuring broader trends. We are addressing this problem through the comparative studies of bedrock exhumation on million-year timescales north and south of the range crest in transects that are not along major trans-Himalayan gorges. Our low-temperature thermochronology dataset from Greater Himalayan Sequence leucogranites and sillimanite gneisses north of the range crest indicate cooling through the white mica 40Ar/39Ar closure isotherm between 15.5 - 14.5 Ma with zircon (U-Th)/He ages ranging from 14.5 - 11 Ma. Though (U-Th)/He systematics of apatites from these samples is complex, our data point to 9 - 8 Ma cooling through the ~70°C isotherm. Our developing dataset from the Khumbu Himal region south of the range crest thus far indicates cooling through ApHe closure occurred more recently at 3 - 2 Ma, about 5 - 6 million years later those from southern Tibet. We will be investigating this dataset further using the 1-D thermal model QTQt as well as the 1-D thermal-kinematic model Pecube.

  12. Exhumation and reburials of some anticommunist partisans in county of Cluj, Romania, 2009-2010

    Directory of Open Access Journals (Sweden)

    Gherasim Florin

    2013-01-01

    Full Text Available After the Second World War, Romania entered under the USSR political and military sphere of influence, which led to the installation of the communist government. In years that followed many Romanian citizens who didn’t agree with the new regime or its ideology were subjected to terror and repression. Any person suspected of being an enemy of the people would end up in political jails or put to death through collective executions. But there were also people who stood up against the regime. Groups of partisans emerged, groups that endured in forests and mountains for many years, standing up to the Securitatea, the repressive instrument of the state. After the fall of the communist regime, the former “enemies of the people”, victims of repression, benefited from reconsideration and rehabilitation that transformed them into anticommunist heroes. A series of commemorative actions that initiated a new post-communist tradition constitute part of a process called the politics of memory. The processes of unearthing and identification of the victims’ served to map out the magnitude of the crimes, and inventory evidence against the perpetrators. The factual data gathered will be used as incriminating evidence which will help with convicting the executioners. At the same time, the commemorative actions of a large number of victims may, through the representative voices of the survivors’ descendants, symbolically reopen the wounds, cultivate trauma, demonize the Other, identify the Scapegoat. My research aims to show how these theories and mechanisms remain valid and apply to the case of people who were victims of communist repression through isolated and almost anonymous executions. The murder was committed in silence and the murdered is condemned to being forgotten. The exhumation and reburial also remain events with local reverberations.

  13. Variation in Magnitude of Differential Stress Across an Exhumed Continental-scale Thrust Zone

    Science.gov (United States)

    Lusk, A. D.; Platt, J. P.

    2015-12-01

    The Moine Thrust Zone (MTZ), located in NW Scotland, formed as a result of the closing of the Iapetus Ocean and docking of various terranes and arcs (Scandian Phase of the Caledonian Orogeny, ca. 445-420 Ma). The MTZ as defined here comprises three major foreland-propagating thrust faults, the latest of which is the Moine Thrust itself, which emplaced Proterozoic Moine Supergroup psammites westward onto Cambro-Ordovician shelf sequence rocks and Lewisian basement gneiss. Presently, the north-south striking Moine Thrust Zone is exposed for more than 200 km along strike, and Scandian deformation can be traced up to 40 km eastward from the Moine Thrust towards the hinterland. The thrust system is thought to have been exhumed while still active, resulting in the exposure of deep structural levels of the MTZ. As part of an ongoing project to study how the stress, rheology, and width of continental-scale faults vary with depth, we use the piezometer based on the grainsize of dynamically recrystallized quartz to determine the variation in magnitude of differential stress across the MTZ. We present a transect from the head of Loch Eriboll in the footwall, eastward to the base of Ben Hope in the hangingwall. Grainsize generally decreases westward and structurally downward to the Moine Thrust, where ultramylonites have grainsizes on the order of 10 μm. Higher stresses towards the foreland likely reflect lower temperatures of deformation in rocks that before thrusting were at higher structural levels, and may have triggered a switch to grainsize sensitive creep, thus resulting in localization of strain and narrowing of shear zone width.

  14. CFD-analysis of buoyancy-driven flow inside a cooling pipe system attached to a reactor pressure vessel

    OpenAIRE

    Petersson, Jens

    2014-01-01

    In this work a cooling system connected to a reactor pressure vessel has been studied using the CFD method for the purpose of investigating the strengths and shortcomings of using CFD as a tool in similar fluid flow problems within nuclear power plants. The cooling system is used to transport water of 288K (15°C) into a nuclear reactor vessel filled with water of about 555K (282°C) during certain operating scenarios. After the system has been used, the warm water inside the vessel will be car...

  15. Buoyancy-Driven Radiative Unsteady Magnetohydrodynamic Heat Transfer over a Stretching Sheet with non-Uniform Heat Source/sink

    Directory of Open Access Journals (Sweden)

    Dulal Pal

    2016-01-01

    Full Text Available In the present study an unsteady mixed convection boundary layer flow of an electrically conduct- ing fluid over an stretching permeable sheet in the presence of transverse magnetic field, thermal radiation and non-uniform heat source/sink effects is investigated. The unsteadiness in the flow and temperature fields is due to the time-dependent nature of the stretching velocity and the surface temperature. Both opposing and assisting flows are considered. The dimensionless governing or- dinary non-linear differential equations are solved numerically by applying shooting method using Runge-Kutta-Fehlberg method. The effects of unsteadiness parameter, buoyancy parameter, thermal radiation, Eckert number, Prandtl number and non-uniform heat source/sink parameter on the flow and heat transfer characteristics are thoroughly examined. Comparisons of the present results with previously published results for the steady case are found to be excellent.

  16. Second-law analysis for buoyancy-driven hydromagnetic couple stress fluid flow through a porous channel

    Science.gov (United States)

    Kareem, Semiu O.; Adesanya, Samuel O.; Vincent, Uchechukwu E.

    2016-08-01

    This paper examines the combined effects of the buoyancy force and of the magnetic field on the entropy generation rate in the flow of a couple stress fluid through a porous vertical channel. The flow's dynamical equations were non-dimensionalised and solved via the application of the Adomian decomposition method (ADM). Variations of some thermo-physical parameters were conducted and discussed, with regard to the physics of the fluid. Our result shows that the entropy generation rate increases as the buoyancy increases in the fluid. In addition, the irreversibility in the flow system results mainly from the fluid's viscosity, ohmic heating, and the buoyancy.

  17. Analytical solution of buoyancy-driven flow and heat transfer in a vertical channel with spatially periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gunes, Hasan [Department of Mechanical Engineering, Istanbul Technical University, Gumussuyu (Turkey)

    2003-12-01

    In this study, we derive analytical expressions describing the variation of field variables in steady, 2-D and 3-D natural convection in a vertical channel with discrete in-space, flush-mounted heat sources. The expressions are valid for sufficiently small Grasof numbers. The solution are governed by the following dimensionless parameters: aspect ratios defining the geometry of the problem, Prandtl number, Grashof number and dimensionless channel reference temperature. Test case solutions are obtained numerically to assess the accuracy of the derived expressions. For small values Gr, the derived expressions are in excellent agreement with the numerical solutions in the entire computational domain. Analytical expressions for the net volume flow rate through the channel and Nusselt number variation are also given. (orig.)

  18. Buoyancy-driven mixing of fluids in a confined geometry; Melange gravitationnel de fluides en geometrie confinee

    Energy Technology Data Exchange (ETDEWEB)

    Hallez, Y

    2007-12-15

    The present work based on Direct Numerical Simulations is devoted to the study of mixing between two miscible fluids of different densities. The movement of these fluids is induced by buoyancy. Three geometries are considered: a cylindrical tube, a square channel and a plane two-dimensional flow. For cylindrical tubes, the results of numerical simulations fully confirm previous experimental findings by Seon et al., especially regarding the existence of three different flow regimes, depending on the tilt angle. The comparison of the various geometries shows that tridimensional flows in tubes or channels are similar, whereas the two-dimensional model fails to give reliable information about real 3D flows, either from a quantitative point of view or for a phenomenological understanding. A peculiar attention is put on a joint analysis of the concentration and vorticity fields and allows us to explain several subtle aspects of the mixing dynamics. (author)

  19. The eastern Central Pamir Gneiss Domes: temporal and spatial geometry of burial and exhumation

    Science.gov (United States)

    Rutte, Daniel; Stearns, Michael; Ratschbacher, Lothar

    2013-04-01

    We present a structural and thermochronologic study of the Gneiss Domes and their cover in the Central Pamir. Emphasis is laid on presentation and discussion of new 40Ar-39Ar dates embedded in two structural profiles through the central Muskol and western Shatput domes. The structure of the Central Pamir is dominated by Cenozoic deformation related to the India-Asia collision. Only few structures of the Phanerozoic amalgamation of the Pamir were not reactivated. The Cenozoic structural development of the Central Pamir can be simplified into three phases: 1) Between initial collision of India and Asia to 28-20 Ma (peak metamorphism, U-Pb monazite) the emplacement of large thrust sheets led to strong north-south shortening;" in the eastern Central Pamir the major thrust sheet has a minimum displacement of 35 km. The stratigraphic thickness of this nappe is ~7 km but its internal structure and thus its true thickness is weakly constrained by the available data. Klippen of Early Paleozoic strata of this thrust sheet south of the Central Pamir Muskol and Shatput domes cover Carboniferous to Triassic strata of the footwall; they can be linked to the Akbaital nappe previously mapped by Russian geologists north of the domes. In the Sasaksu valley of the Muskol dome, the thrust sheet is intruded by a ~36 Ma granodiorite (new U-Pb zircon dates). (2) This crustal imbricate stack is cut by east-trending normal faults and shear zones that define the Central Pamir Gneiss Domes. Normal shear is concentrated along the northern margin of the domes and was the main process associated with exhumation of the domes from ~30 km depth at 20-15 Ma (U-Th/Pb titanite and monazite, Ar-Ar, fission-track geo-thermochronology). One granite at ~35 Ma (U-Pb zircon) pre-dates exhumation while three leucocratic dykes (18-20 Ma U-Pb monazite and zircon) are dated to be coeval with the initial stages of exhumation. Detrital U-Pb zircon ages of the high-grade metasediments indicate that the protoliths

  20. Thrusting between exhumed mantle blocks at the Gorringe Bank (SW Iberian margin): Evidence from combined seismic and gravity modeling

    Science.gov (United States)

    Sallarès, V.; Martinez-Loriente, S.; Prada, M.; Gailler, A.; Gutscher, M.-A.; Bartolome, R.; Gracia, E.

    2012-04-01

    The Gorringe Bank is a massive seamount located offshore the SW Iberian margin that displays one of the largest gravity anomalies on Earth's oceans. To determine its deep seismic structure, a wide-angle seismic transect with OBS/H crossing it from the Tagus to Horseshoe Abyssal plains, was acquired in 2008. The corresponding velocity model, obtained by joint refraction and reflection travel-time inversion, displays a variably-thick sedimentary layer on top of a basement showing a strong vertical velocity gradient and no evidence for a crust-mantle boundary, not only in the Gorringe Bank but also in the adjacent segments of the deep oceanic basins. The seismic structure closely resembles that of exhumed mantle sections described along the Western Iberian margin and largely differs from that of either oceanic or extended continental crust. A velocity-derived density model assuming that the basement is made of serpentinized peridotite matches well the observed gravity anomaly, showing a basement with a variable degree of serpentinization, decreasing from ~90 % at the seafloor to ~20 % at 10 km deep. Our preferred interpretation is that the Gorringe Bank was initially the central segment of an exhumed mantle band that included also the present-day Eastern Tagus and Western Horseshoe basins. This band, which constitutes the southernmost and oldest section of the Western Iberia oceanic domain, was probably exhumed in the Earliest Cretaceous, during the onset of the North Atlantic opening. During the WNW-ESE Neogene compression, the westernmost Horseshoe basin was thrust on top of the easternmost Tagus basin, uplifting the Gorringe Bank.

  1. Detrital apatite (U-Th)/He constraints on the exhumational histories of the Arunachal Pradesh Himalaya and the Shillong Plateau

    Science.gov (United States)

    Staisch, L. M.; Clark, M. K.; Niemi, N. A.; Avdeev, B.

    2010-12-01

    Erosion in the Himalaya is driven largely by a strongly coupled system of extreme climatic conditions and active tectonic processes. Spatial and temporal variations in erosion rates along strike are presumably controlled by differences in local climate, seismicity, deformation rates, and lithology. Quantifying the contribution of each of these parameters to the erosional budget of the Himalaya, however, is a nontrivial problem. The easternmost portion of the Himalayan arc offers a natural laboratory to explore the role of climatic influence on erosion rates. Deformation and uplift of the Shillong Plateau since ~8 Ma has created an orographic barrier ~400 km long that shields the eastern Himalaya, in Arunachal Pradesh, India, from a significant proportion of the precipitation carried by the South Asian Monsoon. Long-term exhumation rates derived from the Himalaya west and east of this orographic barrier have been shown to differ by a factor of ~2, a difference ascribed to reduced climatic forcing of erosion in the lee of the Shillong Plateau. Here we present apatite (U-Th)/He thermochronology data from modern detrital samples collected from northeast India. Between 18-20 single grain ages from each catchment were analyzed in order to calculate erosion rates on a 106 yr timescale. Recently developed Bayesian techniques for the inverse modeling of detrital data were used to derive time-temperature histories for each sample. Recent erosion rates modeled for a single south-facing catchment on the Shillong Plateau are modest, ~0.25 km Myr-1, and show a clear increase in exhumation rates at ~8 Ma from rates of indicate that the easternmost Himalaya, as a whole, experienced a significant increase in exhumation rate in the late Miocene, although the absolute rates are lower than observed throughout the Bhutanese and Nepalese Himalaya. The temporal correlation of this increase suggests a regional cause, possibly reflecting changes in the stress field across the India

  2. Magnetic signature of large exhumed mantle domains of the Southwest Indian Ridge: results from a deep-tow geophysical survey over 0 to 11 Ma old seafloor

    Science.gov (United States)

    Bronner, A.; Sauter, D.; Munschy, M.; Carlut, J.; Searle, R.; Cannat, M.; Manatschal, G.

    2013-12-01

    We investigate the magnetic signature of an ultramafic seafloor in the eastern part of the Southwest Indian Ridge (SWIR). There, detachment faulting, continuous over 11 Myrs, exhumed large areas of mantle derived rocks. These exhumed mantle domains occur in the form of a smooth rounded topography with broad ridges locally covered by a thin highly discontinuous volcanic carapace. We present high-resolution data combining deep-tow magnetics, side-scan sonar images and dredged samples collected within two exhumed mantle domains between 62° E and 65° E. We show that, despite an ultraslow spreading rate, volcanic areas within robust magmatic segments are characterized by well defined seafloor spreading anomalies. By contrast, the exhumed mantle domains, including a few thin volcanic patches, reveal a weak and highly variable magnetic pattern. The analysis of the magnetic properties of the dredged samples and careful comparison between the nature of the seafloor, the deep-tow magnetic anomalies and the seafloor equivalent magnetization suggest that the serpentinized peridotites do not carry a sufficiently stable remanent magnetization to produce seafloor spreading magnetic anomalies in exhumed mantle domains.

  3. Magnetic signature of large exhumed mantle domains of the Southwest Indian Ridge - results from a deep-tow geophysical survey over 0 to 11 Ma old seafloor

    Science.gov (United States)

    Bronner, A.; Sauter, D.; Munschy, M.; Carlut, J.; Searle, R.; Cannat, M.; Manatschal, G.

    2014-05-01

    We investigate the magnetic signature of ultramafic seafloor in the eastern part of the Southwest Indian Ridge (SWIR). There, detachment faulting, continuous over 11 Myr, exhumed large areas of mantle-derived rocks. These exhumed mantle domains occur in the form of a smooth rounded topography with broad ridges locally covered by a thin highly discontinuous volcanic carapace. We present high-resolution data combining deep-tow magnetics, side-scan sonar images and dredged samples collected within two exhumed mantle domains between 62° E and 65° E. We show that, despite an ultra-slow spreading rate, volcanic areas within robust magmatic segments are characterized by well-defined seafloor spreading anomalies. By contrast, the exhumed mantle domains, including a few thin volcanic patches, reveal a weak and highly variable magnetic pattern. The analysis of the magnetic properties of the dredged samples and careful comparison between the nature of the seafloor, the deep-tow magnetic anomalies and the seafloor equivalent magnetization suggest that the serpentinized peridotites do not carry a sufficiently stable remanent magnetization to produce seafloor spreading magnetic anomalies in exhumed mantle domains.

  4. Spatial variation in exhumation rates across Ladakh and the Karakoram: New apatite fission track data from the Eastern Karakoram, NW India

    Science.gov (United States)

    Wallis, David; Carter, Andrew; Phillips, Richard J.; Parsons, Andrew J.; Searle, Michael P.

    2016-03-01

    Characterization of low-temperature cooling histories and associated exhumation rates is critical for deciphering the recent evolution of orogenic regions. However, these may vary significantly over relatively short distances within orogens. It is pertinent therefore to constrain cooling histories and hence exhumation rates across major tectonic boundaries. We report the first apatite fission track ages from the Karakoram Fault Zone in the Eastern Karakoram range, which forms part of the western margin of the Tibetan Plateau. Ten samples, from elevations of 3477-4875 m, have apatite fission track dates from 3.3 ± 0.3 Ma to 7.4 ± 1.1 Ma. The ages correspond to modeled average erosional exhumation rates of 0.67 + 0.27/-0.18 mm/yr across the Eastern Karakoram. The results are consistent with a trend northward from the Indus suture zone, across the Ladakh terrane and into the Karakoram, in which tectonic uplift associated with crustal thickening increases toward the north, raising elevation and promoting glaciation and generation of extreme relief. As a result, erosion and exhumation rates increase south to north. Present-day precipitation on the other hand varies little within the study area and on a larger scale decreases southwest to northeast across this portion of the orogen. The Eastern Karakoram results highlight the diverse patterns of exhumation driven by regional variations in tectonic response to collision along the western margin of Tibet.

  5. Exhumations- und Hebungsgeschichte der zentralen Anden in Südbolivien (21°S) durch Spaltspur-Thermochronologie an Apatit

    OpenAIRE

    Ege, Harald

    2010-01-01

    The Tertiary formation of the Altiplano-Puna plateau at the active continental margin of South America resulted in the doubling of the crust and surface uplift by about 4000 m. The aim of this study is to reconstruct the Tertiary cooling and exhumation history by apatite fission track thermochronology (AFT) and hence to characterise the processes which produced plateau uplift. The study area follows a transect at 21°S in Southern Bolivia across the plateau and the eastern flank of the Andes. ...

  6. A 10 Myrs long record of mantle exhumation at the eastern Southwest Indian Ridge

    Science.gov (United States)

    Sauter, D.; Cannat, M.; Andreani, M.; Birot, D.; Bronner, A.; Brunelli, D.; Carlut, J. H.; Delacour, A.; Guyader, V.; Mendel, V.; Ménez, B.; MacLeod, C. J.; Pasini, V.; Rouméjon, S.; Ruellan, E.; Searle, R. C.

    2011-12-01

    Although detachment faulting is thought to be a fundamental, widespread style of accretion of oceanic lithosphere, the kinematic evolution of faulting and the link between deformation and magmatic emplacement are still poorly known. Here we use newly acquired geological and geophysical data from the eastern Southwest Indian Ridge (SWIR) to address this question. The eastern SWIR displays the widest expanses known to date of seafloor with no evidence for a volcanic upper crustal layer. Deep tow TOBI sidescan sonar images and dredged rock samples were collected over two areas with contrasting styles of non volcanic seafloor. In the first survey area (centered at 62°30'E) several broad smooth elongated and symmetric ridges are oriented SW-NE, oblique to the spreading direction (~NS). TOBI images show that the hillsides of these ridges, facing toward and away from the axial valley, correspond to smooth surfaces with mass wasting features and almost no evidence of volcanism. Some of these ridges display highly backscattering fuzzy textures with rounded shape features of unknown origin. Serpentinized mantle-derived peridotites were systematically dredged in those areas. Volcanic textures are only observed at the eastern and western ends of these ridges. The second survey area (centered at 64°35'E) covers the edge between volcanic and non volcanic seafloor. There, ridges are perpendicular to the spreading direction and display mainly an asymmetric shape. TOBI sidescan sonar images show that the inward facing gentle slope of these ridges are smooth and sedimented surfaces covered locally by small sized volcanic patches. Outward facing slopes are steeper and may be covered with volcanic textures. Serpentinized mantle-derived peridotites were also systematically dredged outside these volcanic areas. We interpret the successive non volcanic ridges as the result of large low angle normal faults which exhume mantle rocks alternatively to the northern and to the southern flank

  7. The Cora Lake Shear Zone, an Exhumed Deep Crustal Lithotectonic Discontinuity, Western Churchill Province, Canada

    Science.gov (United States)

    Regan, S.; Leslie, S.; Holland, M. E.; Williams, M. L.; Mahan, K. H.; Jercinovic, M. J.

    2011-12-01

    Deep crustal flow is a fundamental tectonic process that may serve to reduce topographic gradients, especially in overthickened collisional orogens. Recent studies have utilized numerical models and seismic interpretations, but generally in two dimensions. Although useful, two dimensional models can not fully characterize lower crustal flow or coupling of crustal layers because they cannot fully incorporate lateral heterogeneity in the flow field. The Athabasca Granulite terrane, in northern Saskatchewan, is an exposed deep crustal terrane that underwent granulite grade deformation during the Neoarchean (ca. 2.55), then cooled isobarically for 600 m.y., and then was reactivated during the Paleoproterozoic (ca. 1.9 Ga). Regional exhumation occurred at roughly 1.85 Ga. This exposure, is a field laboratory for studying lower crustal flow, stabilization, and reactivation. Recent work suggests that the northwestern domain, dominated by the multiphase, opx-bearing, Mary batholith, underwent top-to-the-east lower crustal flow during the Neoarchean. The Chipman domain, to the SE , is primarily underlain by the 3.2 Ga, Chipman tonalite straight gneiss, which was likely restitic, and rheologically strong during the 2.6 Ga flow event. The Cora Lake shear zone (CLsz), which divides the two domains, is interpreted to represent a lithotectonic, compositional, and rheologic boundary within the deep crust. Recent mapping of the western gradient of the CLsz has provided insight into the role and evolution of the rheologic discontinuity and its relationship to crustal flow. The Mary granite (gneiss) contains excellent assemblages for P-T and pseudosection analysis. Interlayered felsic granulite contain abundant monazite for in-situ geochronology. An intense subhorizontal tectonic fabric (S1), interpreted to be the product of crustal flow, is present in both units. This early fabric was locally crenulated, folded, and transposed, by a sub-vertical S2 fabric. Current work involves

  8. Continental hyperextension, mantle exhumation, and thin oceanic crust at the continent-ocean transition, West Iberia: New insights from wide-angle seismic

    Science.gov (United States)

    Davy, R. G.; Minshull, T. A.; Bayrakci, G.; Bull, J. M.; Klaeschen, D.; Papenberg, C.; Reston, T. J.; Sawyer, D. S.; Zelt, C. A.

    2016-05-01

    Hyperextension of continental crust at the Deep Galicia rifted margin in the North Atlantic has been accommodated by the rotation of continental fault blocks, which are underlain by the S reflector, an interpreted detachment fault, along which exhumed and serpentinized mantle peridotite is observed. West of these features, the enigmatic Peridotite Ridge has been inferred to delimit the western extent of the continent-ocean transition. An outstanding question at this margin is where oceanic crust begins, with little existing data to constrain this boundary and a lack of clear seafloor spreading magnetic anomalies. Here we present results from a 160 km long wide-angle seismic profile (Western Extension 1). Travel time tomography models of the crustal compressional velocity structure reveal highly thinned and rotated crustal blocks separated from the underlying mantle by the S reflector. The S reflector correlates with the 6.0-7.0 km s-1 velocity contours, corresponding to peridotite serpentinization of 60-30%, respectively. West of the Peridotite Ridge, shallow and sparse Moho reflections indicate the earliest formation of an anomalously thin oceanic crustal layer, which increases in thickness from ~0.5 km at ~20 km west of the Peridotite Ridge to ~1.5 km, 35 km further west. P wave velocities increase smoothly and rapidly below top basement, to a depth of 2.8-3.5 km, with an average velocity gradient of 1.0 s-1. Below this, velocities slowly increase toward typical mantle velocities. Such a downward increase into mantle velocities is interpreted as decreasing serpentinization of mantle rock with depth.

  9. Petrofabrics of high-pressure rocks exhumed at the slab-mantle interface from the "point of no return" in a subduction zone (Sivrihisar, Turkey)

    Science.gov (United States)

    Whitney, Donna L.; Teyssier, Christian; Seaton, Nicholas C. A.; Fornash, Katherine F.

    2014-12-01

    The highest pressure recorded by metamorphic rocks exhumed from oceanic subduction zones is ~2.5 GPa, corresponding to the maximum decoupling depth (MDD) (80 ± 10 km) identified in active subduction zones; beyond the MDD (the "point of no return") exhumation is unlikely. The Sivrihisar massif (Turkey) is a coherent terrane of lawsonite eclogite and blueschist facies rocks in which assemblages and fabrics record P-T-fluid-deformation conditions during exhumation from ~80 to 45 km. Crystallographic fabrics and other features of high-pressure metasedimentary and metabasaltic rocks record transitions during exhumation. In quartzite, microstructures and crystallographic fabrics record deformation in the dislocation creep regime, including dynamic recrystallization during decompression, and a transition from prism slip to activation of rhomb and basal slip that may be related to a decrease in water fugacity during decompression (~2.5 to ~1.5 GPa). Phengite, lawsonite, and omphacite or glaucophane in quartzite and metabasalt remained stable during deformation, and omphacite developed an L-type crystallographic fabric. In marble, aragonite developed columnar textures with strong crystallographic fabrics that persisted during partial to complete dynamic recrystallization that was likely achieved in the stability field of aragonite (P > ~1.2 GPa). Results of kinematic vorticity analysis based on lawsonite shape fabrics are consistent with shear criteria in quartzite and metabasalt and indicate a large component of coaxial deformation in the exhuming channel beneath a simple shear dominated interface. This large coaxial component may have multiplied the exhuming power of the subduction channel and forced deeply subducted rocks to flow back from the point of no return.

  10. H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones

    Science.gov (United States)

    Labrousse, L.; Duretz, T.; Gerya, T.

    2015-10-01

    We present two-dimensional numerical models of plate subduction and collision inspired by the Scandinavian Caledonian orogeny to investigate the possible impact of continental crust partial melting on the exhumation of ultra-high pressure metamorphic rocks. Three possible reactions were tested: low temperature solidus representing H2O-fluid-saturated partial melting, and two end-member reaction curves for dehydration melting. Thermo-mechanical effects of partial melting were implemented as (1) a viscosity decrease as a determined rheologically critical melt percentage was reached (here 0.1), (2) a change in effective heat capacity and adiabatic heating/cooling accounting for a latent heat term in the heat equation. Among the 3 tested reactions, only H2O-fluid-saturated partial melting drastically modifies the collision dynamics from the non-melting reference model holding all other parameters constant. A substantially low general viscosity truncation (here 1017 Pa s) is needed to properly resolve the effect of partial melting on deep collision processes. Low temperature melting indeed induces the development of a low viscosity buoyant plume prior to slab detachment, where migmatites exhume from UHP conditions at rates and with pressure-temperature paths similar to the natural values acknowledged for the Norwegian Caledonides. High temperature melting has no drastic influence on early collision dynamics. While positive buoyancy remains the first order driver for the exhumation of buried continental rocks, exhumation initiates in these cases with eduction subsequent to slab detachment. Melting and formation of a migmatite plume can later occur along decompression path while continental crust undergoes thermal reequilibration at temperatures above 900 °C. Some of the partially molten material can also relaminate in the overriding plate rather than exhume within the collision zone. Even if minor in terms of amount of magma produced, H2O-fluid-saturated partial melting

  11. Insights on high-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW Iberia

    Science.gov (United States)

    José Fernández, Francisco; Llana-Fúnez, Sergio; Valverde-Vaquero, Pablo; Marcos, Alberto; Castiñeiras, Pedro

    2016-04-01

    High-grade, highly deformed gneisses crop out continuously along the Masanteo peninsula and constitute the upper part of the lower crustal section in the Cabo Ortegal nappe (NW Spain). The rock sequence formed by migmatitic quartzo-feldspathic (qz-fsp) gneisses and mafic rocks records the early Ordovician (ca. 480-488 Ma) injection of felsic dioritic/granodioritic dykes at the base of the qz-fsp gneisses, and Devonian eclogitization (ca. 390.4 ± 1.2 Ma), prior to its exhumation. A SE-vergent ductile thrust constitutes the base of quartzo-feldspathic gneissic unit, incorporating mafic eclogite blocks within migmatitic gneisses. A NW-vergent detachment displaced metasedimentary qz-fsp gneisses over the migmatites. A difference in metamorphic pressure of ca. 0.5 GPa is estimated between both gneissic units. The tectono-metamorphic relationships of the basal ductile thrust and the normal detachment bounding the top of the migmatites indicate that both discrete mechanical contacts were active before the recumbent folding affecting the sequence of gneisses during their final emplacement. The progressive tectonic exhumation from eclogite to greenschist facies conditions occurred over ca. 10 Ma and involved bulk thinning of the high-grade rock sequence in the high pressure and high temperature (HP-HT) Cabo Ortegal nappe. The necessary strain was accommodated by the development of a widespread main foliation, dominated by flattening, that subsequently localized to a network of anastomosing shear bands that evolved to planar shear zones. Qz-fsp gneisses and neighbouring mafic granulites were exhumed at > 3 mm yr-1, and the exhumation path involved a cooling of ˜ 20 °C/100 MPa, These figures are comparable to currently active subduction zones, although exhumation P-T trajectory and ascent rates are at the hotter and slower end in comparison with currently active similar settings, suggesting an extremely ductile deformation environment during the exhumation of qz

  12. Geophysical fingerprints of hyper-extended, exhumed and embryonic oceanic domains: the example from the Iberia-Newfoundland rifted margins

    Science.gov (United States)

    Stanton, Natasha; Manatschal, Gianreto; Autin, Julia; Sauter, Daniel; Maia, Marcia; Viana, Adriano

    2016-09-01

    This study investigates the magnetic and gravity signatures and associated seismic character of hyper-extended, exhumed and embryonic oceanic domains along the conjugate Iberia-Newfoundland rifted margins. As these margins have been drilled down to basement along their distal parts, it is possible to explore and test different geophysical techniques and interpretations. The aims of this work are twofold: (1) to investigate the location and nature of the two main marginal boundaries—the necking zone and the J Anomaly, which define the limits of major domains; and (2) to map the lateral variations of gravity and magnetic signatures and their detailed correlation with seismic data, from the proximal margin until the first unequivocal oceanic magnetic anomaly (e.g. C34 Anomaly). The results point out that the J Anomaly corresponds to a first-order tectono-magmatic boundary, with a basement formed by polyphase magmatism. It marks the boundary between the exhumed mantle domain, with little magmatic additions, from a domain oceanwards that reveals comparable trends, frequencies and a general magnetic pattern at both sides of the Atlantic, suggesting a coeval evolution. We propose that the domain between the J and the C34 Anomalies was formed by an embryonic spreading system, with intermittent budgets of magma, similar to those observed at very slow spreading systems. The J Anomaly may thus correspond to the location of lithospheric breakup though its origin and the nature of the domain oceanwards remains to be constrained.

  13. Recent (0-8 Ma) tectonics and exhumation processes in Cordilleras Blanca and Negra, Central Peru: Constraints from (U-Th)/He dating

    Science.gov (United States)

    Margirier, Audrey; Robert, Xavier; Gautheron, Cécile; Audin, Laurence

    2014-05-01

    The Central Andes are a classical example of topography building in front of an oceanic subduction. However, many first order questions are still debated: How do subduction processes and observed tectonic uplift interact along the Andean margin? What is the impact of tectonic, magmatism and climate on exhumation? The Cordilleras Blanca (6768 m) and Negra (5181 m), in north Central Peru, belong to the highest Andean reliefs. Both ranges trend parallel to the subduction zone and are separated by the NW-SE Rio Santa valley. The Cordillera Blanca pluton formed in an active subduction context at 8-5 Ma and renders an abnormal magmatic activity over a planar subduction. In contrast with the Cordillera Blanca, the Cordillera Negra is an older relief, which evolution and exhumation history has never been studied. A remarkable ~200 km-long normal fault system showing ~4500 m of vertical displacement since 5 Ma edges the western flank of the Cordillera Blanca. This region is a perfect target to study the impact of magmatism and subduction processes on exhumation. We perform a morphotectonic study on both cordilleras coupled with low-temperature thermochronology apatite (U-Th)/He dating to quantify these processes. Geomorphic parameters and altitude contrasts between these two ranges indicate a differential uplift. The Cordillera Negra displays a smooth and asymmetric relief from the West to the East whereas the Cordillera Blanca shows higher and sharper relief with North/South and East/West contrasts. We obtain apatite (U-Th)/He ages for twenty samples located along vertical and horizontal profiles at different latitudes of the Cordilleras Blanca and Negra. The (U-Th)/He ages range from 13.4 ± 1.3 to 5.6 ± 0.6 Ma in the Cordillera Negra and range from 11.8 ± 1.2 to 2.0 ± 0.2 Ma in the Cordillera Blanca. We use them as inputs in QTQt tools for time-temperature reconstructions and thus to constrain the exhumation history. Whole ages evidence a more regional exhumation than

  14. The Freyenstein Shear Zone - Implications for exhumation of the South Bohemian Batholith (Moldanubian Superunit, Strudengau, Austria)

    Science.gov (United States)

    Griesmeier, Gerit; Iglseder, Christoph; Konstantin, Petrakakis

    2016-04-01

    infiltration under lower greenschist-facies conditions locally lead to sericitization of feldspar and development of pseudomorphs after it. In addition, syn-mylonitic biotite has been chloritized mimetically. Chlorite growth across the mylonitic foliation occurs rarely. Brittle faulting, overprinting the shear zone features, is documented by the occurrence of numerous harnish planes. They show normal faulting to the N with angles around 30° and locally sinistral shear-sense. The Freyenstein shear zone belongs to a system of NE-SW striking shear zones and faults in the Moldanubian superunit and is located at the border between the SBB and MN ductily deforming both. Therefore, it plays an important role in exhumation processes of last stage SBB (synkinematic) intrusions during Late Variscan orogenic extension. According to cooling ages in other shear zones and (synkinematic) intrusions an age of ca. 320-290 Ma for the ductile deformation can be assumed.

  15. Diverse P-T paths for the Cycladic ultramafic rock associations: Constraints on their origin, emplacement and exhumation

    Energy Technology Data Exchange (ETDEWEB)

    Katzir, Y [Department of Geological and Environmental Sciences, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Garfunkel, Z; Avigad, D; Matthews, A [Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)], E-mail: ykatzir@bgu.ac.il

    2008-07-01

    Within the Alpine orogen of the Cyclades ultramafic rocks occur in diverse tectonic positions, are associated with a variety of rock sequences and are regionally metamorphosed at variable conditions. Here this diversity is interpreted in terms of variable mechanisms for incorporation of mantle rocks into orogenic belts and used to better constrain spatial heterogeneity of P-T burial and exhumation paths in the Cyclades. The Cycladic Blueschist Unit (CBU) was metamorphosed first at high pressure conditions in the Eocene (M1) and variably overprinted during exhumation in the Early Miocene (M2). On the islands of Syros and Evia the CBU includes relatively thin HP-LT ophiolitic melange intervals hosted by meta-sedimentary sequences. Meta-serpentinites are associated with eclogitized metagabbro and metabasites on Syros, but with epidote blueschists on Evia. Given the wide and comparable geochemical heterogeneity in the Syros and Evian melanges, the Syros metabasites record higher M1 temperatures (450-500 deg. C) relative to their Evian counterparts (400-430 deg. C). The M2 overprint is manifested in Syros by greenschist facies assemblages ({approx}450 deg. C), whereas pumpellyite-actinolite assemblage ({approx}350 deg. C) overgrew blueschists in Evia. Within the M2 migmatized leucogneiss core of the Naxos dome ({approx}700{sup 0}C) meta-peridotite lenses are the sole preservers of pre-M2 history. The Naxos meta-peridotites possess relict mantle assemblage, fertile spinel lherzolite chemical composition and mantle-like oxygen isotope ratios. Thus unlike ophiolite-associated ultramafics in the Cyclades that were serpentinized prior to metamorphism, the Naxos metaperidotites were directly emplaced from the subcontinental mantle into an underthrust continent during collision and HP metamorphism. Ultramafic assemblages constrain M1 temperatures on Naxos to 550-650{sup 0}C. It follows that going southeastwards from Evia through Syros to Naxos progressively deeper levels of

  16. Mesozoic exhumation in the coastal region of NW Iberia: Preliminary constraints from apatite fission-track cooling ages

    Science.gov (United States)

    Alvarez-Marrón, Joaquina; Barbero, Luis; Menéndez-Duarte, Rosana; Fernández, Susana

    2013-04-01

    Apatite fission-track (AFT) ages from the Iberian Massif, along the northern coastal region in Galicia are presented. The study aims at unravelling the exhumation history of this higher topography coastal region, the so-called Rías Altas region, next to the northern Iberian margin. The rough topography region is bound to the south by the WNW-ESE trending As Pontes dextral strike-slip fault zone. This fault was active since ca. 30 Ma (Rupelian) up to ca. 21 Ma (Aquitanian). The area comprises mainly Late Proterozoic to Paleozoic metamorphic and igneous rocks from the hinterland of the Variscan orogen. A N-S AFT ages profile from the coast to the southern block of the As Pontes fault reveal progressively younger ages toward the south with the oldest ages (242 ± 12 Ma) located near the coast and the youngest age being 124 ± 7 Ma. The AFT ages at both sides of the As Pontes fault in samples taken at the same elevation are similar within error (124 ± 7and 127 ± 7 Ma) indicating that this strike-slip fault did not cause significant differential exhumation during Oligocene-Early Miocene times. Another important feature shown by these data is that the age-elevation relationship (AER) is negative, the youngest ages being located at the highest elevation (ca. 1000 m. a. s. l). This agrees with recent published data from the easternmost part of the present study area and is an indication of Post-Early Cretaceous long residence time within the upper 2 or 3 km of the crust at temperatures lower than those of the apatite partial annealing zone (60 to 120°C). We interpret the registered exhumation history as mostly related to rifting processes in Pre-Early Cretaceous times. Possibly recording surface processes associated to the two stage rifting episodes in the Triassic and in the Late Jurassic-Early Cretaceous that culminated with formation of the north Iberian Margin. The negative AER suggests that since Early Cretaceous times the whole area underwent topographic changes

  17. Application of Critical-Taper Theory to Oligo-Miocene Extension and Core-Complex Exhumation in Western Arizona, USA

    Science.gov (United States)

    Spencer, J. E.

    2006-12-01

    Restoration of 93 km of Oligo-Miocene extension in the area around the Harcuvar metamorphic core complex in western Arizona reveals three east-southeast-trending belts. From southwest to northeast these are: (1) a basin occupied by the Upper Jurassic to Upper Cretaceous McCoy Mountains Formation and its Jurassic volcanic substrate, (2) the generally southwest-vergent, Late Cretaceous Maria fold-and-thrust belt, and (3) the restored position of the Harcuvar metamorphic core complex in the middle crust beneath Proterozoic bedrock adjacent to the Colorado Plateau. Large-magnitude extension that exhumed the core-complex mylonites began along a narrow, southeast-trending belt that crossed the Maria fold-and-thrust belt at an angle of about ten degrees. Extension in the northwestern part of the area where the two belts crossed was unusual because mylonitic mid-crustal rocks were exhumed with almost no extension of overlying rocks (Buckskin, Rawhide, and Artillery Mountains). This is equivalent to stable sliding of an extensional wedge. In contrast, approximately 100 km to the southeast in the Vulture Mountains area, extension produced a highly distended array of tilted fault blocks with no exhumation of mylonitic mid-crustal rock. This is equivalent to highly unstable sliding of an extensional wedge. Almost every other area in Arizona that is both highly extended and at least moderately well exposed is intermediate in structural style of extension. Juxtaposition of end-member structural styles in western Arizona can be explained by application of critical taper theory to restored paleotopography characterized by a mountain range along the axis of the Maria fold-and-thrust belt. When extension began, the Buckskin-Rawhide detachment fault dipped to the northeast beneath a northeast-sloping surface on the northeast flank of the mountain range, resulting in stable sliding of the hanging-wall rocks. Along strike to the southeast the detachment fault dipped northeast beneath

  18. Low-temperature thermochronology of the northern Thomson Orogen: Implications for exhumation of basement rocks in NE Australia

    Science.gov (United States)

    Verdel, Charles; Stockli, Daniel; Purdy, David

    2016-01-01

    The Tasmanides of eastern Australia record much of the Phanerozoic tectonic development of the retreating Pacific-Australia plate boundary and are an oft-cited example of an orogen that has undergone "tectonic mode switching." To begin to constrain the timing of exhumation of basement rocks that are now exposed in portions of the NE Tasmanides, we measured apatite and zircon (U-Th)/He ages from the Thomson Orogen and overlying Paleozoic strata in the back-arc of the New England Orogen in NE Australia. Zircon (U-Th)/He ages from basement samples (including those recovered from boreholes at depths of up to 1.1 km) are characterized by large inter- and intra-sample variability and range from approximately 180 Ma (Early Jurassic) to 375 Ma (Late Devonian). (U-Th)/He zircon ages from several individual samples are negatively correlated with effective uranium (eU), a pattern that is also true of the dataset as a whole, suggesting that variations in U and Th zoning and radiation damage are partially responsible for the age variability. The oldest zircon (U-Th)/He cooling ages coincide with the formation of regionally extensive Late Devonian-early Carboniferous back-arc basins, suggesting that Late Devonian extension played a significant role in exhumation of parts of the northern Thomson Orogen. Apatite (U-Th)/He ages from a basement sample and a late Permian sandstone in the overlying Bowen Basin, which are also marked by intra-sample variability and age-eU correlations, span from the Early Cretaceous through Oligocene, in general agreement with previous apatite fission track data. In conjunction with observations of key geologic relationships and prior K-Ar and 40Ar/39Ar data, our results suggest four overall phases in the thermal history of the northern Thomson Orogen: (1) Cambrian-early Silurian metamorphism during the Delamerian and Benambran Orogenies; (2) protracted cooling during the Late Devonian through mid-Permian that likely resulted from extensional

  19. Using Detrital Geochronologic and Thermochronologic "Double-Dating" to Constrain Depositional Age, Provenance, and Exhumation Signals in Ancient Forearc Basins

    Science.gov (United States)

    Orme, D. A.

    2014-12-01

    The application of coupled detrital zircon U-Pb geochronology and (U-Th)/He thermochronology to sedimentary basins has the potential for unprecedented details about grain provenance, depositional age and source and basin exhumation signals. Although several studies have implored this technique, it is underutilized and may prove useful in geologic settings that are traditionally difficult to explore. For example, constraining the depositional age of strata in ancient forearc basins is challenging as many horizons are devoid of fossils and post-burial diagenesis of limestone beds limits biostratigraphic age control. This study applies U-Pb detrital zircon geochronology to clastic rocks from the Cretaceous-Eocene Xigaze forearc basin in southern Tibet to (1) to determine the provenance of forearc basin strata and (2) to constrain a maximum depositional age of stratigraphic horizons using the youngest distinct age group from a sample. In addition, (U-Th)/He thermochronology was applied to a subset of the detrital zircons on which U-Pb ages were previously determined in order to determine the timing of exhumation of Xigaze forearc strata and its source region. The use of young populations of zircons is a good method for age control in the Xigaze forearc basin because magmatism in the source area was more-or-less continuous and the lag time between the youngest zircons in a sample and the time of that samples deposition is likely relatively small. A total of 2,330 zircon grains yielded ages with acceptable precision and concordance for geochronologic interpretation. Together with sandstone petrography, the detrital zircons indicate that the primary source of detritus in the basin from ~113 to 54 Ma was the Gangdese magmatic arc. Analysis of the youngest age component of individual samples reveals a decrease in the youngest ages upsection, consistent with maximum depositional ages that are close to the likely true depositional age based on intervening tuff layers. Double

  20. Polyphase evolution of a crustal-scale shear zone during progressive exhumation from ductile to brittle behaviour: a case study from Calabria, Italy

    Directory of Open Access Journals (Sweden)

    E. Fazio

    2015-03-01

    Full Text Available Mylonitic rocks involved within a polyphase crustal-scale shear zone, cropping out in the Aspromonte Massif (Calabria, Italy, has been investigated to reveal the meso- and micro-structural evolution (from ductile- to brittle-type deformation occurred during exhumation trajectory. A relatively small area (about 4 km2 has been selected in the central-eastern part of the massif to constrain the sequence of the structural features from the earliest ones (Hercynian in age, almost totally obliterated by a pervasive mylonitic foliation (plastic regime, up to recent ones, consisting of various sets of veins typical of semibrittle to brittle regime. The former ductile evolution was followed by a compressive thin-skinned thrusting stage developed during the Apennine phase of the Alpine Orogeny, interested by a second brittle stage, consistent with the switching from compressive to extensional tectonics. This last stage accompanied the final exhumation process causing the activation of regional scale normal faults, which partly disarticulated previous mylonitic microstructures. A suite of oriented specimens were collected and analyzed to complete the deformational history already recognized in the field. Quartz c axis orientation patterns confirm the greenschist facies conditions of the former ductile exhumation stage with a dominant top-to-NE sense of shear. Microstructural investigations highlighted the progressive development from plastic- to brittle-type structures, allowing to constrain each step of the multistage exhumation history, and to establish the relative timing of the stress field variation causing thrusting and subsequent normal faulting. Obtained results support a continue compressional exhumation of this sector since the opening of Tyrrhenian basin (10 Ma.

  1. Transient, synobduction exhumation of Zagros blueschists inferred from P-T, deformation, time, and kinematic constraints: Implications for Neotethyan wedge dynamics

    Science.gov (United States)

    Agard, P.; Monié, P.; Gerber, W.; Omrani, J.; Molinaro, M.; Meyer, B.; Labrousse, L.; Vrielynck, B.; Jolivet, L.; Yamato, P.

    2006-11-01

    We present the first P-T, deformation time, and kinematic constraints on the only known blueschist facies rocks (BS) present in the Zagros (Hajiabad area). The BS were underplated below the Sanandaj-Sirjan zone and crop out as kilometer-scale bodies within extensive colored melange units marking discontinuously the Neotethyan suture zone. P-T estimates point to high-pressure/low-temperature (HP-LT) conditions around 11 kbar and 520-530°C for the majority of BS, along a ˜15°C km-1 gradient. Some exotic blocks in matrix serpentinite reached 17-18 kbar at ˜500°C. In situ laser probe 40Ar-39Ar radiometric age constraints on phengite cluster between 85 and 95 Ma and suggest that (1) synconvergence exhumation of Zagros BS from 35-50 km to depths <15-20 km was accomplished before 80 Ma, (2) BS exhumation corresponded to a transient process with respect to the long-lived subduction beneath Iran (˜150-35 Ma), and (3) age constraints for Zagros BS are 5-10 Myr older than for the nearby Oman HP-LT rocks and broadly coincide with obduction processes in the region (circa 95-70 Ma). We propose that the mechanical coupling across the Neotethyan subduction zone (NSZ) beneath Iran was modified by the large-scale plate rearrangement accompanying obduction, allowing for a short-lived exhumation of Zagros BS. Exhumation ceased at the end of obduction, when subduction of the Arabian continental margin stopped. Kinematic calculations suggest that convergence velocities across the NSZ likely doubled (to ˜5-6 cm yr-1) during the period 118-85 Ma, so that BS exhumation may have been promoted by a combination of obduction movements and increased convergence velocities.

  2. Mesozoic exhumation history and palaeolandscape of the Iberian Massif in eastern Galicia from apatite fission-track and (U+Th)/He data

    Science.gov (United States)

    Grobe, R. W.; Alvarez-Marrón, J.; Glasmacher, U. A.; Stuart, F. M.

    2014-03-01

    Apatite fission-track (AFT) and (U+Th)/He (AHe) data, combined with time-temperature inverse modelling, reveal the cooling and exhumation history of the Iberian Massif in eastern Galicia since the Mesozoic. The continuous cooling at various rates correlates with variation of tectonic boundary conditions in the adjacent continental margins. The data provide constraints on the 107 timescale longevity of a relict paleolandscape. AFT ages range from 68 to 174 Ma with mean track lengths of 10.7 ± 2.6 to 12.6 ± 1.8 μm, and AHe ages range from 73 to 147 Ma. Fastest exhumation (≈0.25 km/Ma) occurred during the Late Jurassic to Early Cretaceous main episode of rifting in the adjacent western and northern margins. Exhumation rates have decreased since then and have been approximately one order of magnitude lower. Across inland Galicia, the AFT data are consistent with Early Cretaceous movement on post-Variscan NE trending faults. This is coeval with an extensional episode offshore. The AHe data in this region indicate less than 1.7 km of denudation in the last 100 Ma. This low exhumation suggests the attainment of a mature landscape during Late Cretaceous post-rift tectonic stability, whose remains are still preserved. The low and steady rate of denudation prevailed across inland Galicia despite minor N-S shortening in the northern margin since ≈45 Ma ago. In north Galicia, rock uplift in response to NW strike-slip faulting since Early Oligocene to Early Miocene has caused insufficient exhumation (<3 km) to remove the Mesozoic cooling signal recorded by the AFT data.

  3. Multiple low-temperature thermochronology constraints on exhumation of the Tatra Mountains: New implication for the complex evolution of the Western Carpathians in the Cenozoic

    Science.gov (United States)

    Anczkiewicz, Aneta Agnieszka; Danišík, Martin; Środoń, Jan

    2015-11-01

    The tectonothermal evolution of the highest mountain range in the Carpathian arc—the Tatra Mountains— is investigated by zircon and apatite fission track and zircon (U-Th)/He (ZHe) dating methods in order to unravel the disputed exhumation and geodynamic processes in the Western Carpathians. Our data in combination with geological evidences reveal a complex Cenozoic history, with four major tectonothermal events: (i) a very low grade metamorphism of the crystalline basement at temperatures >240°C due to tectonic burial during the Eo-Alpine collision in the Late Cretaceous (~80 Ma); (ii) exhumation and cooling of the basement to temperatures 150°C after burial to 5-9 km depths by the Paleogene fore-arc basin; (iv) final exhumation of the segmented basement blocks during Oligocene-Miocene (32-11 Ma) owing to lateral extrusion of the North Pannonian plate and its collision with the European foreland. The spatial pattern of thermochronological data suggests asymmetric exhumation of the Tatra Mountains, beginning in the northwest at ~30-20 Ma with low cooling rates (~1-5°C/Ma) and propagating toward the major fault bounding the range in the south, where the youngest cooling ages (16-9 Ma) and fastest cooling rates (~10-20°C/Ma) are found. Our data prove that the Tatra Mountains shared Cenozoic evolution of other crystalline core mountains in the Western Carpathians. However, the Miocene ZHe ages suggest that the Tatra Mountains were buried to the greatest depths in the Paleogene-Early Miocene and experienced the greatest amount of Miocene exhumation.

  4. Phanerozoic burial and exhumation history of southernmost Norway estimated from apatite fission-track analysis data and geological observations

    Science.gov (United States)

    Japsen, Peter; Green, Paul F.; Bonow, Johan M.; Chalmers, James A.; Rasmussen, Erik S.

    2016-04-01

    We present new apatite fission-track analysis (AFTA) data from 27 basement samples from Norway south of ~60°N. The data define three events of cooling and exhumation that overlap in time with events defined from AFTA in southern Sweden (Japsen et al. 2015). The samples cooled below palaeotemperatures of >100°C in a major episode of Triassic cooling as also reported by previous studies (Rohrman et al. 1995). Our study area is just south of the Hardangervidda where Cambrian sediments and Caledonian nappes are present. We thus infer that these palaeotemperatures reflect heating below a cover that accumulated during the Palaeozoic and Triassic. By Late Triassic, this cover had been removed from the Utsira High, off SW Norway, resulting in deep weathering of a granitic landscape (Fredin et al. 2014). Our samples were therefore at or close to the surface at this time. Palaeotemperatures reached ~80°C prior to a second phase of cooling and exhumation in the Jurassic, following a phase of Late Triassic - Jurassic burial. Upper Jurassic sandstones rest on basement near Bergen, NW of our study area (Fossen et al. 1997), and we infer that the Jurassic event led to complete removal of any remaining Phanerozoic cover in the region adjacent to the evolving rift system prior to Late Jurassic subsidence and burial. The data reveal a third phase of cooling in the early Miocene when samples that are now near sea level cooled below palaeotemperatures of ~60°C. For likely values of the palaeogeothermal gradient, such palaeotemperatures correspond to burial below rock columns that reach well above the present-day landscape where elevations rarely exceed 1 km above sea level. This implies that the present-day landscape was shaped by Neogene erosion. This is in agreement with the suggestion of Lidmar-Bergström et al. (2013) that the near-horizontal Palaeic surfaces of southern Norway are the result of Cenozoic erosion to sea level followed by uplift to their present elevations in a

  5. Basin Evolution and Exhumation of the Xigaze Forearc, Southern Tibet: Insight from Sedimentology, Stratigraphy, and Geo-Thermochronology

    Science.gov (United States)

    Orme, D. A.; Carrapa, B.; Abbey, A. L.; Kapp, P. A.; Ding, L.

    2012-12-01

    Miscellanea-Daviesina. The along-strike variability of the Cretaceous strata suggests that, prior to collision, the diverse and irregular paleogeography of Asia's southern margin greatly influenced the three-dimensional nature and distribution of time-equivalent facies. In order to determine the timing of exhumation of Xigaze forearc strata, we utilize zircon (U-Th)/He thermochronology coupled with U-Pb geochronology. Preliminary U-Pb detrital geochronology indicates that the primary source of forearc detritus is the Gangdese magmatic arc which was active from ~150 Ma to 50 Ma. Preliminary double-dated (U-Th/He and U-Pb) zircon crystals from eight samples in ~80 Ma deposits suggest basin exhumation from 30 to 10 Ma. This time span corresponds to ages determined independently for movements occurring along the basin-bounding Great Counter Thrust system. Therefore, we postulate that this fault system was responsible for erosional exhumation of the Xigaze forearc.

  6. Mazatan metamorphic core complex (Sonora, Mexico): structures along the detachment fault and its exhumation evolution

    Science.gov (United States)

    Granillo, Ricardo Vega; Calmus, Thierry

    2003-08-01

    The Mazatán Sierra is the southernmost metamorphic core complex (MCC) of the Tertiary extensional belt of the western Cordillera. Its structural and lithological features are similar to those found in other MCC in Sonora and Arizona. The lower plate is composed of Proterozoic igneous and metamorphic rocks intruded by Tertiary plutons, both of which are overprinted by mylonitic foliation and N70°E-trending stretching lineation. Ductile and brittle-ductile deformations were produced by Tertiary extension along a normal shear zone or detachment fault. Shear sense is consistent across the Sierra and indicates a top to the WSW motion. The lithology and fabric reflect variations in temperature and pressure conditions during extensional deformation. The upper plate consists mainly of Cambrian-Mississippian limestone and minor quartzite, covered by upper Cretaceous volcanic rocks, and then by Tertiary syntectonic sedimentary deposits with interbedded volcanic flows. Doming caused uplift and denudation of the detachment, as well as successive low-angle and high-angle normal faulting across the western slope of Mazatán Sierra. An 18±3 Ma apatite fission-track age was obtained for a sample of Proterozoic monzogranite from the lower plate. The mean fission-track length indicates rapid cooling and consequent rapid uplift of this sample during the last stage of crustal extension.

  7. High-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW of Iberia

    Directory of Open Access Journals (Sweden)

    F. J. Fernández

    2015-12-01

    Full Text Available High-grade highly deformed gneisses crop out continuously along the Masanteo peninsula in the Cabo Ortegal nappe (NW Spain. The rock sequence formed by quartzo-feldspathic gneisses and mafic rocks records two partial melting events: during the Early Ordovician (ca. 480–488 Ma., at the base of the Qz-Fsp gneisses, and immediately after eclogization (ca. 390.4 ± 1.2 Ma, during its early Variscan exhumation. Despite the strain accumulated during their final exhumation in which a pervasive blastomylonitic S2 foliation was developed, primary sedimentary layering in Qz-Fsp gneisses is well preserved locally at the top of the sequence. This first stage of the exhumation process occurred in ~ 10 Ma, during which bulk flattening of the high-grade rock sequence was accommodated by anastomosing shear bands that evolved to planar shear zones. Strain was progressively localized along the boundaries of the migmatitic Qz-Fsp gneisses. A SE-vergent ductile thrust constitutes the base of gneisses, incorporating eclogite blocks-in-matrix. A NW-vergent detachment placed the metasedimentary Qz-Fsp gneisses over the migmatitic Qz-Fsp gneisses. A difference in metamorphic pressure of ca. 0.5 GPa is estimated between both gneissic units. The high-grade deformation reduced substantially the thickness of the gneissic rock sequence during the process of exhumation controlled by change in the strain direction and the progressive localization of strain. The combined movement of the top detachment and basal thrust resulted in an extrusion of the migmatites within the nappe, directed to the SE in current coordinates.

  8. Poisson's Ratio Structure Through a Zone of Exhumed Mantle at the Goban Spur Rifted Margin, Southwest of the UK.

    Science.gov (United States)

    Bullock, A. D.; Minshull, T. A.

    2004-12-01

    Zones of exhumed mantle have been identified at the west Iberia and Goban Spur rifted margins in the eastern North Atlantic where they form a transition zone up to 130 km wide between thinned continental crust and oceanic crust further seaward. P-wave velocities range from ˜4~km~s-1 at top basement to 7.2-7.6~km~s-1 at 4-6~km depth into basement and taken in isolation are consistent with a wide range of contrasting lithologies. Poisson's ratio may be used as a discriminator between possible compositions as, for P-wave velocities sonobuoys across this region at a separation of ˜15~km; S-wave arrivals are observed on five ocean-bottom hydrophones in this region as P-to-S conversions occurring at top basement. A regularised inversion with smoothing constraints was used to define the P- and S-wave velocity structures individually and the Poisson's ratio computed from these models.

  9. Sediments overlying exhumed continental mantle: a proxy for the morphotectonic evolution of the Ocean Continent Transition in magma-poor rifted margins

    Science.gov (United States)

    Karpoff, A. M.; Manatschal, G.; Bernoulli, D.; Lagabrielle, Y.

    2003-04-01

    Observations from ancient and present-day magma-poor rifted margins in the Alps and Iberia provide compelling evidence that within the ocean-continent transition (OCT) crustal and sub-continental mantle rocks were exhumed along downward-concave faults which were active during final rifting and accommodated high amounts of extension. The faults are overlain by stranded allochthons of continental origin, pillow basalts, and pelagic sediments, i.e. radiolarites and/or pelagic limestones, and hemipelagic shales. Associated with the faults are tectono-sedimentary breccias and various types of clastic sediments, ranging from debris flow deposits to laminated sandstone, and quartz-rich silt- and claystones. Mineralogical studies of the shales, red jaspers, and red cherts overlying mantle rocks in the Alps of eastern Switzerland are typically quartz-rich and contain variable amounts of phyllosilicates (chlorite and/or mica), feldspars, ± calcite, oxides, pyrite, and epidote. Their main geochemical characteristic is the high silica and low iron and manganese content, which contrasts with that of "metalliferous" Fe-Mn-Si-rich sediments overlying oceanic basalts. High Fe, Ba, REE, U/Th values measured in black shales overlying mantle rocks in the proximal OCT point to a strong hydrothermal activity associated with mantle exhumation. The clastic sediments in the OCT show a wide range of compositions related to mantle, continental crust, and/or pelagic contributions. In particular, the fact that these sediments contain abundant material derived from continental basement rocks seems at odds with their occurrence on top of tectonized mantle rocks. However, drilling in the Iberia margin, where tectonized mantle rocks are overlain by sedimentary breccias (e.g. ODP Sites 1068, 1070), shed new light on the observations in the Alps. Based on drill-hole and seismic data, the tectono-sedimentary breccias drilled in the OCT off Iberia may be interpreted to result from a conveyor

  10. The anatomy of the Cycladic Blueschist Unit on Sifnos Island (Cyclades, Greece): implications for exhumation model of high-pressure rocks

    Science.gov (United States)

    Roche, Vincent; Laurent, Valentin; Jolivet, Laurent; Cardello, Giovanni Luca; Scaillet, Stéphane

    2015-04-01

    Key words.- Aegean sea, Cyclades, Sifnos, high pressure and low temperature metamorphism, syn-orogenic exhumation, post-orogenic extension, strain localization. Since 35 Ma, the kinematics of the Aegean domain has been mainly controlled by the southward retreat of the African slab, inducing backarc extension. The main structures and associated kinematic are well constrained, but the kinematics of deformation before 35 Ma, coeval with the exhumation of blueschists and eclogites of the Cycladic Blueschist Unit, has been so far poorly studied. Hence, syn-orogenic deformation and exhumation mechanisms of the Cycladic Blueschists Unit remain disputed in part because the structure and kinematic history of High Pressure and Low Temperature (HP-LT) rocks are interpreted differently in the literature. In order to understand and constrain the exhumation history of HP-LT rocks, Sifnos Island is particularly relevant because HP-LT parageneses are exceptionally well preserved and different degree of retrogression are observed in two main units. The aims of this work attempts at firstly solving uncertainties on the position and geometry of major contacts between units and, secondly, to provide new structural constraints on the tectonic history of HP-LT units generated in the subduction zone during the Eocene. We show, through new geological and metamorphic maps, cross-sections and analyses of kinematic indicators and their relation to metamorphism, that Sifnos is characterized by shallow-dipping shear zones reactivating weak zones due to competence contrasts or earlier tectonic contacts (i.e., syn-orogenic). Structures and kinematics, associated with these shear zones, show a top-to-the-N to -NE ductile shearing deformation. A continuum of deformation can be observed from the Eocene syn-orogenic blueschist-facies to the Oligocene-Miocene post-orogenic greenschist-facies with the same top-to-the-NE sense of shear showing that the same shear zones, formed during syn

  11. Ongoing compression triggered exhumation of the orogenic crust in the Variscan Maures-Tanneron Massif, France - Geological arguments and thermo-mechanical tests

    Science.gov (United States)

    Gerbault, Muriel; Schneider, Julie; Reverso-Peila, Alexandre; Corsini, Michel

    2016-04-01

    The Maures-Tanneron Massif (MTM), together with Corsica and Sardinia, hosted the South-Eastern Variscan belt and record a continuous evolution from continental collision to exhumation. We present a synthesis of the available geological and geochronogical data that explores the transition from convergence to perpendicular Permean extension in the MTM (at ~ 325 Ma ± 25 My). The migmatitic Internal Zone that composes the Western MTM displays structural clues such as backthrusting and magmatic foliations, and metamorphic data indicating exhumation of deep seated partially molten rocks at an apparent heating rate of 1-2 °C/km/My from ca. 345 Ma to 320 Ma. This suggests vertical advective heat transport during continued N140° convergence (D2 phase). In contrast at the same time, the low grade External zone composing the Eastern part of the MTM recorded exhumation of more conductive patterns at an apparent rate of 0.3-0.6 °C/km/My. It is only from ca. 320 Ma that transcurrent motion dominates in the Internal zone and progressively leaves way to N-S strecthing (D3 phase), indicative of orogenic collapse and extension and in asociation with emplacement of larger volumes of magmatism in the crust. Thermo-mechanical modeling complements this synthesis in order to highlight the conditions under which deep seated HP units could melt and massively start to exhume during maintained convergence (phase D2). Accounting for temperature dependent elasto-visco-plastic rheologies, our models explore the dynamics of an orogenic prism starting from a dis-equilibrated state just after slab break-off or delamination, at ca. 350 Ma. We simulate the development of gravitational instabilities in partially melting crust, a process that is already well known to depend on strain-rate, heat sources and strength layering. In order to reproduce the exhumation patterns of rocks from ~50 km depth over the appropriate time-scale (>20 My) and spatial extent (>100 km), a best fit was obtained with a

  12. Exhumation Degree of the Tianshan Range and Its Implications for Ore Preservation%天山山脉剥露程度与矿产保存关系初探

    Institute of Scientific and Technical Information of China (English)

    陈正乐; 周永贵; 韩凤彬; 陈柏林; 郝瑞祥; 李松彬; 刘增仁

    2012-01-01

    异是造成所谓“大矿不过国界”的主要原因之一.%The exhumation of ore-bearing rocks after mineralization plays an important role in the ore preservation, and their relation is one of major issues of mineral deposit geology. The number percentage and area proportion of intermediate-acid intrusive bodies are regarded as two indexes of mountain exhumation degree in this paper. The temperature-space distribution of current outcropped deposits in Tianshan range not only is helpful for understanding the relationship between the mountain exhumation with the preservation of early-formed deposits, but also facilitates further ore-prospecting. Statistics results show that there are very few number and little area proportion of intermediate-acid intrusive bodies in Yilianhabigaer mountain in western segment of north Tianshan, Bogeda mountain in middle segment of north Tianshan, and southwest Tianshan, where there are only few outcropped metal ore deposits mainly characterized by epithermal mineralization. And relative deeply intrusive rocks, as well as lots of large to super-large intrusive-rock-related meso-hypothermal ore deposits, are widely exposed in Jueluotage area in southern part of north Tianshan, middle Tianshan unit, and Kuluketage area in eastern segment of south Tianshan. Previous data from fission track dating of apatite shows that Yilianhabigaer mountain, Bogeda mountain, and southwest Tianshan in-itially uplifted at the end of the Mesozoic, followed by rapid uplift and deformation since about ca. 25 Ma Mountains in middle Tianshan, southern part of north Tianshan, and eastern segment of south Tianshan begun to uplift rapidly and denudate since the Early Jurassic, but only weak uplift occurred in the Cenozoic. The outcropped rocks, the distribution characteristics of metal ore deposits, and the uplift-exhumation process of mountains suggest that superficial volcano-sedimentary rocks are still preserved in Yilianhabigaer mountain, Bogeda mountain

  13. New Constraints on the Timing and Magnitude of Deformation and Basin Exhumation in the Eastern Cordillera of NW Argentina.

    Science.gov (United States)

    Trimble, J. D.; Carrapa, B.; Stockli, D. F.; Stutz, J.

    2008-12-01

    could be potentially related to the reactivation of Cretaceous relay-zone structures. Flexural-slip folding is the dominant mechanism of folding within the basin, with centimeter to meter scale fracture-rich and slickenside-rich beds of fine silts acting as primary slip-surfaces between thicker, more competent beds of coarse sand and conglomerate. A newly discovered intra-formational angular unconformity near the base of the Angastaco Fm. documents growth during the early stages of deposition. However, there is no clear evidence of continuous growth up section, implying at least two pulses of significant deformation during syn- and post- Miocene time. New apatite (U-Th)/He thermochronology (AHe) from six samples from the Eocene-Oligocene(?) Quebrada de los Colorados Fm and the Miocene Angastaco Fm (~18 Ma) in the Angastaco and surrounding Pucara and Tin Tin basins yields youngest ages between ca. 13.2 Ma (to the west) and ca. 10.3 Ma (to the east), and correlate with low Uranium content. We interpret these ages as representative of cooling following basin exhumation in the Miocene. The younging of those ages towards the east, together with structural data indicating young Mio-Pliocene deformation, suggests that those ages may be the result of eastward propagation of deformation into the foreland driving basin exhumation.

  14. Hydrothermal alteration in an exhumed crustal fault zone: geochemical mobility in the Caleta Coloso Fault, Atacama Fault System, Northern Chile

    Science.gov (United States)

    Arancibia, G.; Fujita, K.; Hoshino, K.; Mitchell, T. M.; Cembrano, J. M.; Gomila, R.; Morata, D.; Faulkner, D. R.; Rempe, M.

    2013-12-01

    Fault zones must be considered as complex and heterogeneous systems, with areas of high permeability that alternate with very low permeability bands. Strike-slip fault zones play an important role in fluid migration in the crust, and exhumed faults can provide insights into the interrelationships of deformation mechanisms, fluid-rock interactions and bulk chemical redistributions. We determined the mineral chemistry and whole-rock geochemistry of the damage zone and fault core of the Caleta Coloso Fault, a complex major crustal scale strike-slip fault in Northern Chile, in order to constrain the physical and chemical conditions of fluids that lead to strong hydrothermal alteration. Caleta Coloso Fault consists of variably altered protocataclasites, cataclasites and discrete bands of ultracataclasite derived from a protolith of Jurassic tonalite. Hydrothermal alteration associated with fault-related fluid flow is characterized by a very low-grade association composed by chlorite, epidote, albite, quartz and calcite. Chlorite thermometry indicates T-values in the range of 284 to 352 °C (average temperature of 323 °C) and no differences in mineral composition or T-values were observed among different cataclastic rock types. Mass balance and volume change calculations document that the major chemical mobility was observed in protocataclasite, whereas cataclasite and ultracataclasite show smaller changes. This suggests that fluid flow and chemical alteration post-dated the faulting, when the protocataclasite was relatively permeable and the cataclasite and ultracataclasite acted as a barrier for fluid flow having a very low permeability due to extreme grain size reduction during cataclasis.

  15. Characterization and simulation of an exhumed fractured petroleum reservoir. Final report, March 18, 1996--September 30, 1998

    Energy Technology Data Exchange (ETDEWEB)

    Forster, C.B.; Nielson, D.L.; Deo, M.

    1998-12-01

    An exhumed fractured reservoir located near Alligator Ridge in central Nevada provides the basis for developing and testing different approaches for simulating fractured petroleum reservoirs. The fractured analog reservoir comprises a 90 m thickness of silty limestone and shaly interbeds within the Devonian Pilot Shale. A period of regional compression followed by ongoing basin and range extension has created faults and fractures that, in tern, have controlled the migration of both oil and gold ore-forming fluids. Open pit gold mines provide access for observing oil seepage, collecting the detailed fracture data needed to map variations in fracture intensity near faults, build discrete fracture network models and create equivalent permeability structures. Fault trace patterns mapped at the ground surface provide a foundation for creating synthetic fault trace maps using a stochastic procedure conditioned by the outcrop data. Conventional simulations of petroleum production from a 900 by 900 m sub-domain within the reservoir analog illustrate the possible influence of faults and fractures on production. The consequences of incorporating the impact of different stress states (e.g., extension, compression or lithostatic) are also explored. Simulating multiphase fluid flow using a discrete fracture, finite element simulator illustrates how faults acting as conduits might be poorly represented by the upscaling procedures used to assign equivalent permeability values within reservoir models. The parallelized reservoir simulators developed during this project provide a vehicle to evaluate when it might be necessary to incorporate very fine scale grid networks in conventional reservoir simulators or to use finely gridded discrete fracture reservoir simulators.

  16. Burial and exhumation of temperate bedrock reefs as elucidated by repetitive high-resolution sea floor sonar surveys: Spatial patterns and impacts to species' richness and diversity

    Science.gov (United States)

    Storlazzi, Curt D.; Fregoso, Theresa A.; Figurski, Jared D.; Freiwald, Jan; Lonhart, Steve I.; Finlayson, David P.

    2013-03-01

    To understand how chronic sediment burial and scour contribute to variation in the structure of algal and invertebrate communities on temperate bedrock reefs, the dynamics of the substrate and communities were monitored at locations that experience sand inundation and adjacent areas that do not. Co-located benthic scuba-transect surveys and high-resolution swath-sonar surveys were completed on bedrock reefs on the inner shelf of northern Monterey Bay, CA, in early winter 2009, spring 2010, and summer 2010. Analysis of the sonar surveys demonstrates that during the 8 months over which the surveys were conducted, 19.6% of the study area was buried by sand while erosion resulted in the exposure of bedrock over 13.8% of the study area; the remainder underwent no change between the surveys. Substrate classifications from the benthic transect surveys correlated with classifications generated from the sonar surveys, demonstrating the capacity of high-resolution sonar surveys to detect burial of bedrock reefs by sediment. On bedrock habitat that underwent burial and exhumation, species' diversity and richness of rock-associated sessile and mobile organisms were 50-66% lower as compared to adjacent stable bedrock habitat. While intermediate levels of disturbance can increase the diversity and richness of communities, these findings demonstrate that burial and exhumation of bedrock habitat are sources of severe disturbance. We suggest that substrate dynamics must be considered when developing predictions of benthic community distributions based on sea floor imagery. These results highlight the need for predictive models of substrate dynamics and for a better understanding of how burial and exhumation shape benthic communities.

  17. 滇西石鼓杂岩南部早白垩世以来剥露隆升的锆石和磷灰石裂变径迹证据%The exhumation and uplift of the southern Shigu complex since Early Cretaceous evidenced by zircon and apatite fission track

    Institute of Scientific and Technical Information of China (English)

    陈小宇; 刘俊来; 吴文斌

    2016-01-01

    石鼓杂岩位于青藏高原东南缘经历了多期变质变形作用叠加。为了揭示杂岩体的低温热演化与浅部剥露历史,采集了石鼓杂岩南段石鼓镇-拉巴支村剖面变质岩中的锆石和磷灰石,开展裂变径迹分析。结果表明,石鼓杂岩从早白垩世(133~145Ma)到渐新世(31Ma)经历了一次缓慢的剥露(1.08℃/Ma),而从渐新世开始,其南部经历了较快速的剥露过程(3.23℃/Ma)。磷灰石热史模拟也反映出第二阶段较为快速的冷却过程。结合区域构造分析认为,拉萨与羌塘板块碰撞的远程效应影响早白垩世以来藏东地区地壳结构的调整,导致石鼓杂岩南部出现了第一阶段的剥露作用;而印度与欧亚板块碰撞与后碰撞过程对于石鼓杂岩的新生代剥露具有重要影响。%The Shigu complex lies on the southeastern margin of the Tibetan Plateau, and is mainly distributed in Shigu and Zhongdi⁃an areas. The complex has experienced polyphase superposition of metamorphism and deformation. In order to reveal the low tem⁃perature thermal evolution and exhumation history at the shallow crustal level of the complex and correctly understand the exhuma⁃tion and tectonic evolution of the metamorphic dome in eastern Tibet, the authors collected zircon and apatite fission track samples for the fission track analysis along the Shigu Town-Labazhi section. The analytical results show that the Shigu complex firstly experi⁃enced a slow cooling and exhumation from Early Cretaceous (133~145Ma) to Oligocene (31Ma), and a relatively rapid cooling pro⁃cess started from Oligocene. Time-temperature history simulated by inverse modeling of apatite fission track also reflects a relatively rapid cooling process at the second stage. From regional structural analysis, it is suggested that the far-field effects of the collision be⁃tween the Lhasa and Qiangtang plates may have strongly affected the Early Cretaceous

  18. Étude des anomalies magnétiques dans les domaines de manteau exhumé : apport sur les processus de l'océanisation

    OpenAIRE

    Bronner, Adrien

    2013-01-01

    The aim of this work is to constrain (1) whether exhumation of mantle rocks at mid oceanic ridges is compatible with the record of polarity reversals of the Earth magnetic field, (2) what is the origin and the processes responsible for the magnetic anomalies observed at magma-poor rifted margins and (3) what are the consequences of these processes on continental breakup. In a first part, in order to work with high-resolution data, we develop a method for calibration and interpretation of deep...

  19. Petrology of HP/LT metapelitic rocks of an accretionary wedge, the Central Pontides, Turkey: evidence for tectonic stacking and syn-subduction exhumation

    Science.gov (United States)

    Aygül, Mesut; Okay, Aral; Oberhänsli, Roland

    2015-04-01

    Cretaceous HP/LT chloritoid-bearing metapelitic rocks crop out widely in the central part of the Pontides, northern Turkey. They are associated with eclogite to blueschist-facies metabasites and represent deep levels of an underplated subduction-accretion complex, which is tectonically overlain by low-grade HP phyllite/metasandstone intercalation along an extensional shear zone. Close to the shear zone, the footwall micaschists consist of quartz, phengite, paragonite, chlorite, rutile with syn-kinematic albite porphyroblast formed by pervasive shearing during exhumation. This type of micaschists is tourmaline-bearing and their retrograde nature suggests high-fluid flux along shear zones. Peak metamorphic assemblages are partly preserved in the chloritoid-micaschist farther away from the shear zone. Three peak metamorphic assemblages are identified and their PT conditions are constrained by pseudosections produced by Theriak-Domino and by Raman spectra of carbonaceous material: 1) garnet-chloritoid-glaucophane with lawsonite pseudomorphs (P: 17.5 ± 1 Kbar, T: 390-450 °C) 2) chloritoid with glaucophane pseudomorphs (P: 16-18 Kbar, T: 475 ± 40 °C) and 3) relatively high-Mg chloritoid (17%) with jadeite pseudomorphs (22-25 Kbar; T: 440 ± 30 °C) in addition to phengite, paragonite, quartz, chlorite, rutile. The last mineral assemblage is interpreted as transformation of the chloritoid + glaucophane assemblage to chloritoid + jadeite paragenesis with increasing pressure. Absence of tourmaline suggests that the chloritoid-micaschist did not interact with B-rich fluids during zero strain exhumation. Peak metamorphic assemblages and PT estimates suggest tectonic stacking within wedge with different depths of burial. 40Ar/39Ar phengite age of a pervasively sheared footwall micaschist is constrained to 100.6 ± 1.3 Ma and that of a chloritoid-micaschist is constrained to 91.8 ± 1.8 Ma suggesting exhumation during on-going subduction. Coupling and exhumation of the

  20. Hot, Fast Faults: Evidence for High-Temperature Slip on Exhumed Faults, and Insights into Seismic Slip Processes

    Science.gov (United States)

    Evans, J. P.; Ault, A. K.; Janecke, S. U.; Prante, M. R.

    2015-12-01

    Microstructural and geochemical techniques combined with prior observations of naturally occurring faults provide insights into slip rates and slip dimensions of seismicity. We review four indicators for high coseismic paleotemperatures in brittle to semi-brittle faults from a wide range of tectonic settings with mm to km of slip. Thin, high-gloss, Fe-rich slip surfaces indicate high-temperature slip occurred on mm- to m-scales. Elliptical and circular zones of concentric iridescence indicate localized sites of elevated temperature that may be caused by heating at asperity contacts. The surface iridescence is associated with changes in Fe oxidation states detected by X-Ray photoelectron spectroscopy. Minimum temperature increases of 300 °C above ambient are supported by geochemical arguments and up to 800 °C are supported by analogs to high-speed friction experiments in steels and ceramics firing in reduced conditions. The presence of clay-rich foliated fault-related rocks, and the presence of nm- to mm-thick clay coatings indicate that syn-kinematic endothermic reactions occur at a range of scales. We suggest these features reflect temperature increases of ≥100-200 °C for activation energy required to drive the clay alteration is sourced from seismic energy and Schleicher-van der Pluijm-type slip surfaces to record instantaneous slip. Dense, low porosity planar porcelainite zones mm- to cm-thick along fault surfaces are the result of sintering of quartz-clay-feldspar mixtures and indicate T≥1000 °C localized along the surfaces, the result of post-slip cooling. Highly indurated, ultrafine fault-related rocks often consists of comminuted grains, vein fragments, and neocrystallized grains that represent retrograde cooling or alteration after peak heating. These observations and those of other recent workers indicate that many naturally occurring exhumed faults record elevated temperatures. In many cases, careful observations can delineate fault slip

  1. Mineral chemistry, P-T-t paths and exhumation processes of mafic granulites in Dinggye, Southern Tibet

    Institute of Scientific and Technical Information of China (English)

    LIU; Shuwen; ZHANG; Jinjiang; SHU; Guiming; LI; Qiugen

    2005-01-01

    the amphibolite facies metamorphism with pressure of 0.4 to 0.75 GPa and temperature at between 660 and 700℃. These construct P-T paths from crustal subduction overthickening to tectonic uplift tectonothermal evolution. The mineral chemical characteristics and P-T condition at every metamorphic stage of these granulites indicate that these rocks experienced the eclogite facies metamorphism during the early stage. Subsequently, these mafic granulites underwent the three-stage exhumation of the eclogite facies tectonic uplift, isostatic uplift related to the transformation from eclogite/high-pressure granulite to granulite facies and extensional uplift.

  2. Intermediate-depth Fracturing of Oceanic Lithosphere in Subduction Zones: Memories from Exhumed High-Pressure Ophiolites

    Science.gov (United States)

    Angiboust, Samuel; Oncken, Onno; Agard, Philippe

    2014-05-01

    Understanding processes acting along the subduction interface is crucial to assess lithospheric scale coupling between tectonic plates and mechanisms causing intermediate-depth seismicity. Despite a wealth of geophysical studies aimed at better characterizing/localizing this seismicity, we still critically lack constrains on processes triggering fracturing in regions (40-100km depths; T > 400°C) where deformation is expected to be achieved by plastic flow. We herein attempt to bridge this gap by providing a review of available evidence from brittle deformation patterns in exhumed High Pressure (HP) ophiolites, together with some new, critical observations. Field examples from various ophiolitic terranes (New-Caledonia, W. Alps, Tian Shan…) indicate that brittle deformation under HP conditions generally implies vein filling and precipitation of HP minerals, probably under very high pore fluid pressure conditions. Coalescence of such vein networks could explain some of the seismic events recorded along the fluid-rich subduction interface region. By contrast, HP pseudotachylites (though reported in only few localities so far) are apparently restricted to somehow deeper slab regions where fluid-deficient conditions are prevalent (Corsica, Zambia, Voltri?). The recent discovery of eclogite breccias, found as m-sized dismembered fragments within an eclogite-facies shear zone from the Monviso area (W. Alps), provides a new opportunity to study the genesis of intermediate-depth earthquakes. We herein argue that these eclogite breccias constitute unique remnants from an ancient fault zone associated with intraslab, intermediate-depth seismicity at ca. 80 km depth. The breccia is internally made of 1-10 cm-sized rotated fragments of eclogite mylonite cemented by an eclogite-facies matrix attesting of fracturing and fault sealing under lawsonite-eclogite facies conditions (550°C, 2.5 GPa) during subduction of the Tethyan seafloor. Textural observations and polyphased

  3. K-Ar dating of late Mesozoic volcanism and geochemistry of volcanic gravels in the North Huaiyang Belt, Dabie orogen: Constraints on the stratigraphic framework and exhumation of the northern Dabie orthogneiss complex

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Two eruption episodes are identified through systematic field investigations and K-Ar dating of the lateMesozoic volcanic rocks in the North Huaiyang belt (NHB),Dabie orogenic belt, of which the earlier volcanic suitetermed Maotanchang Fm. (Fm.) occurring at Jinzhai,Xianhualing and Maotanchang, etc., was erupted from 149Ma to 138 Ma. The other named Xiaotian Fm. mainly dis-tributed at Xiaotian, Shucheng, etc., was formed between132 Ma and 116 Ma. During the eruption gap of the two vol-canic suites deposited a volcano-sedimentary conglomeratelayer, which are composed of the multi-compositional gravels, including the North Dabie orthogneiss complex (NDOC),volcanic gravels, etc. These volcanic gravels in the con-glomerate layer show identical geochemical and isotopic compositions (87Sr/86Sr(t) =0.7084-0.7092, (Nd (t) = 21.8-24.4) to the Maotanchang Fm. volcanic rocks (87Sr/86Sr = 0.7086-0.7102, (Nd = 19.2-24.4), but significantly distinct from those of Xiaotian Fm. (87Sr/86Sr = 0.7076-0.7084, (Nd = 17.2 - 19.2). K-Ar dating results of its underlying andoverlying volcanic sequences indicate that the conglomerate layers were deposite d at ~135 Ma. This suggests that the NDOC was rapidly exhumed to the surface dur ing or shortly before ~135 Ma and became the important provenance of the late Me sozoic volcano-sedimentary basins in the NHB. In combination with the regional v olcano-sedimentary correlation, we divided the Mesozoic stratigraphic sequence i n the NHB from base to top into Fanghushan Fm. (>160 Ma), Yuantongshan Fm. (/mid dle- lower segment of Sanjianpu Fm.) (160-149 Ma), Maotanchang Fm. (/Zhougongsh an Fm./upper segment of Sanjianpu Fm./Fenghuangtai Fm.) (149-135 Ma) and Xiaoti an Fm. (/Baidafan Fm./Heshidu Fm.) (135-116 Ma).

  4. Rapid long-term erosion in the rain shadow of the Shillong Plateau, Eastern Himalaya

    Science.gov (United States)

    Adlakha, Vikas; Lang, Karl A.; Patel, R. C.; Lal, Nand; Huntington, Katharine W.

    2013-01-01

    Geodynamic models of collisional orogens suggest that precipitation gradients profoundly influence spatial patterns of exhumation and deformation in active collisional mountain ranges. A basic tenet of this hypothesis is that in unglaciated areas, spatial patterns of long-term precipitation, erosion and exhumation should be correlated. A correlation of this type has been observed in the Eastern Himalaya, where uplift of the Shillong Plateau by Pliocene time drastically reduced monsoonal rainfall in the Himalayan range downwind. Existing apatite fission-track data suggest that the resulting precipitation gradient caused a twofold gradient in long-term erosion rates across an area with similar geology, suggesting a strong influence of climate on the region's geomorphic and tectonic evolution. We extend this dataset by presenting 53 new bedrock apatite and zircon fission-track ages from deeper within the rain shadow. We expected latest Miocene to Pliocene apatite ages, similar to previously published ages from neighboring areas in the rain shadow. Instead, apatites as young as 1.3 ± 0.2 Ma and zircons as young as 4.5 ± 1.0 Ma (2σ) demonstrate that spatial gradients in precipitation do not correlate with variations in long-term erosion and crustal strain as predicted by geodynamic models. Thermal-kinematic modeling of these data suggests that local exhumation patterns reflect gradients in rock uplift dictated by fault kinematics in this rapidly deforming area, despite a dramatic precipitation gradient. These findings both highlight the need to better understand how erosive processes scale with precipitation amount and intensity in such settings, and suggest a disconnect between the predictions of orogen-scale geodynamic models and the relationship between erosion and tectonics at the regional scale.

  5. Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A detailed tectonic analysis demonstrates that the present observed regional tectonic configuration of the ultrahigh-pressure metamorphic terrane in the Dabie massif was mainly formed by the extension processes of the post-Indosinian continent-continent oblique collision between the Sino-Korean and Yangtze cratons and ultrahigh-pressure metamorphism (UHPM). The configuration is characterized by a regional tectonic pattern similar to metamorphic core complexes and by the development of multi-layered detachment zones. On the basis of the identification of compressional and extensional fabrics, it is indicated that the exhumation and uplift of ultrahigh-pressure (UHP) metamorphic rocks from the mantle depth to the surface can be divided into at least three different decompression retrogressive metamorphism and tectonic deformation stages, in which the subhorizontal crustal-scale extensional flow in the middle-lower crust under amphibolite facies conditions is an important geodynamic process in the exhumation of UHP metamorphic rocks. Moreover, the extensional flow is probably driven by delamination and magmatic underplating of thickened lithospheric mantle following the continental oblique collision.

  6. Knickzone propagation in the Black Hills and northern High Plains: a different perspective on the late Cenozoic exhumation of the Laramide Rocky Mountains

    Science.gov (United States)

    Zaprowski, Brent J.; Evenson, Edward B.; Pazzaglia, Frank J.; Epstein, Jack B.

    2001-01-01

    Geomorphic research in the Black Hills and northern High Plains poses an intriguing hypothesis for the Cenozoic evolution of this salient of the Laramide Rockies. Most recently, geologists have appealed to late Cenozoic epeirogenic uplift or climate change to explain the post-Laramide unroofing of the Rockies. On the basis of field mapping and the interpretation of long-valley profiles, we conclude that the propagation of knickzones is the primary mechanism for exhumation in the Black Hills. Long profiles of major drainages show discrete breaks in the slope of the channel gradient that are not coincident with changes in rock type. We use the term knickzones to describe these features because their profiles are broadly convex over tens of kilometers. At and below the knickzone, the channel is incising into bedrock, abandoning a flood plain, and forming a terrace. Above the knickzone, the channel is much less incised, resulting in a broad valley bottom. Numerous examples of stream piracy are documented, and in each case, the capture is recorded in the same terrace level. These observations are consistent with migrating knickzones that have swept through Black Hills streams, rearranging drainages in their wake. We demonstrate there are two knickzone fronts associated with mapped terraces. Preliminary field evidence of soil development shows that these terraces are time transgressive in nature. Our data strongly suggest that knickzone propagation must be considered a viable mechanism driving late Cenozoic fluvial incision and exhumation of the northern High Plains and adjacent northern Rocky Mountains.

  7. Trace element behavior and P-T-t evolution during partial melting of exhumed eclogite in the North Qaidam UHPM belt (NW China): Implications for adakite genesis

    Science.gov (United States)

    Zhang, Guibin; Niu, Yaoling; Song, Shuguang; Zhang, Lifei; Tian, Zuolin; Christy, Andrew G.; Han, Lei

    2015-06-01

    We have studied trace element behavior and timing of decompression melting of UHP rocks during exhumation recorded in the magmatic products, i.e., the melt phase (leucosomes), cumulate (garnetite) and residue (amphibolitized eclogite) from a single outcrop in the south Dulan area, North Qaidam UHPM belt, NW China. Two distinct episodes of partial melting are recognized. First, Grt-free tonalitic-trondhjemitic leucosome melts with higher silica crystallized at 424.0 ± 2.7 Ma. Garnets grew in the leucosome melt but fractionated out to form garnetite cumulates along with Ti-rich phases (rutile and titanite), strengthening the adakitic signature of the leucosome. Later Grt-bearing leucosome melts with an age of 412.4 ± 2.9 Ma cross-cut boudins and layers of amphibolitized eclogite. Geochemical investigation of bulk-rocks and in situ minerals verifies the genetic relationship between the amphibolitized eclogite and the tonalitic-trondhjemitic melts. Zircons from the amphibolitized eclogite have older (> 700 Ma) protolith ages, with subsequent eclogite-facies metamorphism, retrograde granulite-facies overprinting and partial melting. Phase modeling and Zr-in-rutile thermometry calculations in combination with zircon geochronology reveal the evolution P-T-t path for the exhumation and the partial melting of the deeply subducted continental crust at the North Qaidam subduction zone in the Early Paleozoic.

  8. Use of fracture filling mineral assemblages for characterizing water-rock interactions during exhumation of an accretionary complex: An example from the Shimanto Belt, southern Kyushu Japan

    Science.gov (United States)

    Ono, Takuya; Yoshida, Hidekazu; Metcalfe, Richard

    2016-06-01

    Various fracture filling minerals and secondary minerals in fracture walls were formed by fluid-rock interaction during the exhumation of the Palaeogene Shimanto Belt of Kyushu, Japan, which is located in an accretionary complex. Each mineral formed under favourable geological conditions and can be used to estimate the conditions of accretion and formation of the related rock sequences. Petrographic observations, mineralogical and geochemical analyses were made on fracture filling minerals and secondary minerals from boreholes of ca. 140 m depth, drilled in the Shimanto Belt. Results reveal that the secondary minerals were formed in three major stages distinguished by the sequential textural relationships of the minerals and the interpreted environment of mineral formation. Filling mineral assemblages show that the studied rock formation has been subducted to a depth of several km and the temperature reached was ca. 200-300 °C. After the subduction, the rock formation was uplifted and surface acidic water penetrated up to 80 m beneath the present ground surface. The acid water dissolved calcite fracture filling minerals to form the present groundwater flow-paths, which allowed recent wall rock alteration to occur. The results shown here imply that filling mineral assemblages can be an effective tool to evaluate the environmental changes during exhumation of an accretionary complex.

  9. Effects of Caribbean oceanic plateau shallow subduction on topographic uplift and exhumation of the northwestern Maracaibo block, Colombia

    Science.gov (United States)

    Sanchez, J.; Mann, P.

    2013-12-01

    The Maracaibo block in the northwestern South America is a triangular lithotectonic terrane bounded on its western edge by the Santa Marta-Bucaramanga left-lateral strike-slip fault and the Oca-Ancon right-lateral strike-slip fault on its northern edge. These faults bound two isolated Andean ranges within the Maracaibo block: the Sierra de Santa Marta massif (SSM) in the east whose highest point is 5700 m ASL, and the Serrania del Perija (SP) to the west, whose highest point is 3600 m ASL. The two ranges are separated by an elongate, NNE-trending sedimentary basin, the Cesar-Rancheria basin (CRB). Previous thermochronological studies in the region have shown three discrete exhumation pulses from Paleocene to Miocene that are attributed to various collisional and strike events along the Caribbean margin. However the tectonic origin of the late Neogene deformation that produced the isolated, high topography of the SSM and SP has remained unclear. To establish patterns of recent uplift and associate them with a specific tectonic mechanism affecting the area, we integrated the following results: 1) analysis of stream profiles using channel normalized steepness indices and identification of slope-break knickpoints as indicators of rock uplift; 2) integration of observations from geological maps; 3) interpretation of 2D onland seismic profiles; 4) analysis of published thermochronological data; and 5) analysis of 1D/2D basin model based on well subsidence analysis from the CRB. Our results from the extraction of 550 long stream profiles from different watersheds for the SSM and SP reveal: 1) undisturbed profiles at western flank of the northern SP characterized by a few vertical-step knickpoints associated with lithology changes; in contrast the eastern flank of the northern SP shows slope-break knickpoints and changes in steepness indices increasing by a factor of ~2, all indicative of active fault control affecting this area; 2) disturbed profiles in the elevated

  10. 40Ar/39Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai,East China

    Institute of Scientific and Technical Information of China (English)

    LI Jinyi; YANG Tiannan; CHEN Wen; ZHANG Sihong

    2003-01-01

    Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai regionof East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlierductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittledeformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these twoevents. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, whichare structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicatingthat the earlier event of the ampibolite-facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating oforiented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of213.1 ±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatiticbiotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 203.4±0.3 Ma,203.6±0.4 Ma and 204.8±2.2 Ma, and isochron ages of 204.0±2.0 Ma, 200.6±3.1 Ma and 204.0±5.0 Ma, respectively,implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 204 Ma). The integration of these data with previous chronological ageson the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocksin the area were exhumed at the rate of 3-4 km/Ma from the mantle (about 80-100 km below the earth's surface at about240 Ma) to the lower crust (at the depth of about 20-30km at 220 Ma), and at the rate of 1-2 km/Ma to the middle crust (atthe depth of about 15 km at 213 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km deep

  11. Tracking the timing of subduction and exhumation using 40Ar/39Ar phengite ages in blueschist- and eclogite-facies rocks (Sivrihisar, Turkey)

    Science.gov (United States)

    Fornash, Katherine F.; Cosca, Michael A.; Whitney, Donna L.

    2016-07-01

    Geochronologic studies of high-pressure/low-temperature rocks can be used to determine the timing and rates of burial and exhumation in subduction zones by dating different stages of the pressure-temperature history. In this study, we present new in situ UV laser ablation 40Ar/39Ar phengite ages from a suite of lawsonite blueschist- and eclogite-facies rocks representing different protoliths (metabasalt, metasediment), different structural levels (within and outside of a high-strain zone), and different textural positions (eclogite pod core vs. margin) to understand the timing of these events in an exhumed Neo-Tethyan subduction zone (Sivrihisar Massif, Tavşanlı Zone, Turkey). Weighted mean in situ 40Ar/39Ar ages of phengite from the cores of lawsonite eclogite pods (90-93 Ma) are distinctly older than phengite from retrogressed, epidote eclogite (82 ± 2 Ma). These ages are interpreted as the age of peak and retrograde metamorphism, respectively. Eclogite records the narrowest range of ages (10-14 m.y.) of any rock type analyzed. Transitional eclogite- and blueschist-facies assemblages and glaucophane-rimmed lawsonite + garnet + phengite veins from eclogite pod margins record a much wider age range of 40Ar/39Ar ages (~20 m.y.) with weighted mean ages of ~91 Ma. Blueschists and quartzites record more variable 40Ar/39Ar ages that may in part be related to structural position: samples within a high-strain zone at the tectonic contact of the HP rocks with a meta-ultramafic unit have in situ UV laser ablation 40Ar/39Ar ages of 84.0 ± 1.3-103.7 ± 3.1 Ma, whereas samples outside this zone range to older ages (84.6 ± 2.4-116.7 ± 2.7 Ma) and record a greater age range (22-38 m.y.). The phengite ages can be correlated with the preservation of HP mineral assemblages and fabrics as well as the effects of deformation. Collectively, these results show that high-spatial resolution UV laser ablation 40Ar/39Ar phengite data, when considered in a petrologic and structural

  12. Sediment dynamics and the burial and exhumation of bedrock reefs along an emergent coastline as elucidated by repetitive sonar surveys: Northern Monterey Bay, CA

    Science.gov (United States)

    Storlazzi, C.D.; Fregoso, T.A.; Golden, N.E.; Finlayson, D.P.

    2011-01-01

    Two high-resolution bathymetric and acoustic backscatter sonar surveys were conducted along the energetic emergent inner shelf of northern Monterey Bay, CA, USA, in the fall of 2005 and the spring of 2006 to determine the impact of winter storm waves, beach erosion, and river floods on biologically-important siliclastic bedrock reef habitats. The surveys extended from water depths of 4 m to 22 m and covered an area of 3.14 km2, 45.8% of which was bedrock, gravel, and coarse-grained sand and 54.2% was fine-grained sand. Our analyses of the bathymetric and acoustic backscatter data demonstrates that during the 6 months between surveys, 11.4% of the study area was buried by fine-grained sand while erosion resulted in the exposure of bedrock or coarse-grained sand over 26.5% of the study area. The probability of burial decreased with increasing water depth and rugosity; the probability of exhumation increased with increasing wave-induced near-bed shear stress, seabed slope and rugosity. Much of the detected change was at the boundary between bedrock and unconsolidated sediment due to sedimentation and erosion burying or exhuming bedrock, respectively. In a number of cases, however, the change in seabed character was apparently due to changes in sediment grain size when scour exposed what appeared to be an underlying coarser-grained lag or the burial of coarser-grained sand and gravel by fine-grained sand. These findings suggest that, in some places, (a) burial and exhumation of nearshore bedrock reefs along rocky, energetic inner shelves occurs over seasonal timescales and appears related to intrinsic factors such as seabed morphology and extrinsic factors such as wave forces, and (b) single acoustic surveys typically employed for geologic characterization and/or habitat mapping may not adequately characterize the geomorphologic and sedimentologic nature of these types of environments that typify most of the Pacific Ocean and up to 50% of the world's coastlines.

  13. The Formation Mechanism of Coesite Far from Equilibrium Phase-Boundary and the Physical Foundation of Hypothesis of Plate Subduction Exhumation in the Earth%远离平衡相边界的柯石英形成机制及板块折返假说的物理基础

    Institute of Scientific and Technical Information of China (English)

    苏文辉

    2011-01-01

    physics,it is very hard to subduct solid continental crust rock into solid crust—mantle rock. Chopin firstly evaded the original driving force, and further,drew a constant equal sign without scientific basis between the two events of the coesite and diamond ultrahigh pressure metamorphic rock found in the Earth's crust and the stable phase produced in the mantle or the deep subduction, and then again rose up to a “paradigm” height that had misled need no original driving force of research. Since the introduction of the hypothesis of plate subduction—exhumation so far, the original driving force of plate subduction—exhumation has always not been resolved. Uneven solid Earth is a natural high-temperature high-pressure system, in order to preserve the coesite, a high-temperature high-pressure phase of quartz, the rapid cooling rate of plate is requested over 40℃ / Ma that should be comparable with the laboratory critical rate of quenching under pressure-keeping (which requires not less than (0. 5 ~ 1.0) x 102℃ / s) , however,there is a huge differential in 1013 order of magnitude for both cases. From the lab phase change regularity of high-temperature high-pressure, such extremely slow cooling rates of plate exhumation is difficult to keep the living coesite. Conversely, in order to make plate exhumation speed reached laboratory critical cooling rate of keeping coesite quenching under pressure, the speed ( in air) of plate exhumation must achieve 10 ~ 20km/s. This meant that to make a huge amount matter with such great speed fast penetrate and exhumation in the solid medium that needs a giant abnormal rare driving force of exhumation, however, from physics viewpoint it is extremely difficult to achieve. In addition, the four important factors put forward by Chopin, influencing the coesite preserve during turn-back process, still exist many problems,and also could not overcome the above paradoxes. The time of atomic diffusion and chemical reaction in solid

  14. Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif,China

    Institute of Scientific and Technical Information of China (English)

    索书田; 钟增球; 游振东

    2000-01-01

    A detailed tectonic analysis demonstrates that the present ob served regional tectonic configuration of the ultrahigh-pressure metamorphic terrane in the Da bie massif was mainly formed by the extension processes of the post-lndosinian continent-continent oblique collision between the Sino-Korean and V’angtze cratons and ultrahigh-pressure metamorphism (UHPM). The configuration is characterized by a regional tectonic pattern similar to metamorphic core complexes and by the development of multi-layered detachment zones. On the basis of the identification of compressional and extensional fabrics, it is indicated that the exhumation and uplift of ultrahigh-pressure (UHP) metamorphic rocks from the mantle depth to the surface can be divided into at least three different decompression retrogressive metamo rphism and tectonic deformation stages, in which the subhorizontal crustal-scale extensional flow in the middle-lower crust under amphibolite facies conditions is an important geodynamic process in the exhu

  15. Syn-exhumation partial melting and melt segregation in the Sulu UHP terrane: Evidences from leucosome and pegmatitic vein of migmatite

    Science.gov (United States)

    Song, Yanru; Xu, Haijin; Zhang, Junfeng; Wang, Deyuan; Liu, Endong

    2014-08-01

    In order to investigate partial melting and melt evolution during exhumation of deeply subducted continental crust, we carried out a combined study on layered leucosomes and pegmatitic veins from the Weihai-Rongcheng migmatites in the Sulu ultra-high pressure (UHP) metamorphic terrane, eastern China. The leucosomes are millimetric to centimetric in thickness and mainly consists of K-feldspar + quartz + plagioclase. The pegmatitic veins emplace along the compositional layers or crosscut them and are mainly composed of K-feldspar + quartz. CL images show that most zircon grains of the leucosomes have a core-rim zoning structure, whereas zircons of the pegmatitic veins are mostly new growth grains with rarely preserved relict domains. The inherited zircon domains (ca. 750 Ma) are of a magmatic origin with zircon εHf(t) values between - 5.7 and 5.3 (mean = - 0.8 ± 1.5), suggesting that the protolith rock is a Mid-Neoproterozoic juvenile crust. The zircon overgrowth rims (223 ± 3 Ma) of the leucosomes and the new zircon grains (217 ± 2 Ma) of the pegmatitic veins formed in equilibrium with melt and are similar to magmatic zircons in terms of their CL images and trace element compositions, e.g., heavy-enriched REE patterns (i.e., very low (Gd/Lu)N ratios) with positive Ce and variably negative Eu anomalies, high Y contents and low Hf/Y ratios. Compared with the inherited protolith zircon domains, the Triassic zircon domains of the leucosomes and the pegmatitic veins have obviously high U but low Th contents, resulting in very low Th/U ratios (< 0.09). The low Th/U ratios (< 0.1) of zircons suggest that Th/U ratio cannot be used to discriminate igneous/metamorphic zircons. The zircons of the pegmatitic veins have remarkably lower Th/U ratios (0.00008-0.01, mostly < 0.006) than those of zircon rims of the leucosomes (0.006-0.09), suggesting that the melt segregation process can also result in low Th/U ratios of zircons. Calculated growth temperature for the zircon

  16. Exhumation history of an active fault to constrain a fault-based seismic hazard scenario: the Pizzalto fault (central Apennines, Italy) example.

    Science.gov (United States)

    Tesson, Jim; Pace, Bruno; Benedetti, Lucilla; Visini, Francesco; Delli Rocioli, Mattia; Didier, Bourles; Karim, keddadouche; Gorges, Aumaitre

    2016-04-01

    A prerequisite to constrain fault-based and time-dependent earthquake rupture forecast models is to acquire data on the past large earthquake frequency on an individual seismogenic source and to compare all the recorded occurrences in the active fault-system. We investigated the Holocene seismic history of the Pizzalto normal fault, a 13 km long fault segment belonging to the Pizzalto-Rotella-Aremogna fault system in the Apennines (Italy). We collected 44 samples on the Holocene exhumed Pizzalto fault plane and analyzed their 36Cl and rare earth elements content. Conjointly used, the 36Cl and REE concentrations show that at least 6 events have exhumed 4.4 m of the fault scarp between 3 and 1 ka BP, the slip per event ranging from 0.3 to 1.2 m. No major events have been detected over the last 1 ka. The Rotella-Aremogna-Pizzalto fault system has a clustered earthquake behaviour with a mean recurrence time of 1.2 ka and a low to moderate probability (ranging from 4% to 26%) of earthquake occurrence over the next 50 years. We observed similarities between seismic histories of several faults belonging to two adjacent fault systems. This could again attest that non-random processes occurring in the release of the strain accumulated on faults, commonly referred to as fault interactions and leading to apparent synchronization. If these processes were determined as being the main parameter controlling the occurrence of earthquakes, it would be crucial to take them into account in seismic hazard models.

  17. Using Sequential Kinematic and Thermochronometric Modeling to Temporally and Spatially Link Thrust Belt Exhumation with Basin Development in the Bolivian Fold-Thrust-Belt-Foreland Basin System.

    Science.gov (United States)

    Rak, A. J.; McQuarrie, N.

    2014-12-01

    Applying isostasy and erosion to sequentially deformed balanced cross sections links the growth of hinterland structures to the developing foreland basins (FB) adjacent to fold-thrust belts (FTB), adding geologic constraints to modeled exhumation pathways. We sequentially deform the Rio Beni cross section in northern Bolivia (McQuarrie et al., 2008) with kinematic modeling software Move. In our model, topography evolves and basins develop for each model step as deformation, erosion, and isostasy are applied; and are a direct function of the geometry and kinematics of the cross section. The model is constrained by the depth of the foreland and hinterland basins, geology present at the surface, the depth and angle of the decollement, and the shape of the modern observed topography. Topography develops as thrusting occurs and loads the crust, producing a flexural wave and creating accommodation space in adjacent basins. Erosion of material above a newly generated topographic profile unloads the section while basin space is filled. Once the model sufficiently duplicates geologic constraints, a 0.5 km X 0.5 km grid of unique points is deformed with the model and used to determine displacement vectors for each 10 km shortening step. These displacement vectors, in conjunction with a prescribed time interval for each step, determine a velocity field that can be used in a modified version of the advection diffusion modeling software Pecube. Cooling ages predicted using this method are based on deformation rates, geometry, topography, and thermal parameters, and offer insight into possible rates of deformation, erosion, and deposition throughout FTB and FB development. Incorporating erosion, deposition, and isostasy in sequentially deformed balanced cross sections highlights the spatiotemporal aspects of sedimentary wedge propagation, identifies necessary external negative buoyancy affects, and provides additional geologic constraints to modeled exhumation pathways.

  18. Instantaneous healing of micro-fractures during coseismic slip: Evidence from microstructure and Ti in quartz geochemistry within an exhumed pseudotachylyte-bearing fault in tonalite

    Science.gov (United States)

    Bestmann, Michel; Pennacchioni, Giorgio; Mostefaoui, Smail; Göken, Mathias; de Wall, Helga

    2016-06-01

    Exhumed faults within the tonalitic Adamello pluton (Southern Alps) were seismic at depth as indicated by the presence of pseudotachylytes (solidified friction-induced melts). During cooling of tonalite, early-formed joints were first exploited by localized ductile shear zones associated with deposition of quartz veins (at ~ 500 °C), and later by pseudotachylyte-bearing cataclastic faults (at ~ 250-300 °C ambient temperature). Adjacent to pseudotachylytes, quartz of the host tonalite shows pervasive thin (1-10 μm wide) healed micro-fractures and ultra-fine (1-2 μm grain size) recrystallized aggregates along micro-shear zones. Under cathodoluminescence (CL) the healed micro-fractures have a darker gray shade than the host "magmatic" quartz that reflects a change in Ti concentrations ([Ti]) as indicated by NanoSIMS measurements. [Ti] vary from 35-55 ppm in the CL-lighter host quartz to 10-13 ppm along the CL-darker healed micro-fractures. These [Ti] were inherited by the ultra-fine recrystallized aggregates that overprinted both the magmatic quartz and the healed micro-fractures during the high temperature transient related to frictional seismic slip. Based on Ti-in-quartz thermometry, we infer that micro-fracture healing occurred at higher temperatures than the ambient temperatures of faulting (250-300 °C at 0.2 GPa), for which [Ti] history, referable to the short-lived (on the order of 104 s) thermal anomaly induced by frictional seismic slip, that includes both micro-fracture healing and recrystallization. This microstructural assemblage of the natural exhumed fault provides a key for understanding the mechanics of an earthquake source.

  19. Mesozoic and Cenozoic uplift and exhumation of the Bogda Mountain, NW China:Evidence from apatite fission track analysis

    Institute of Scientific and Technical Information of China (English)

    Wenhao Tang; Zhicheng Zhang; Jianfeng Li; Ke Li; Zhiwen Luo; Yan Chen

    2015-01-01

    Apatite fission track (AFT) analysis on samples collected from a Paleozoic series is used to constrain the cooling history of the Bogda Mountain, northwest China. AFT ages range from 136.2 to 85.6 Ma and are younger than rock depositional ages and the mean confined track lengths (11.0e13.2 mm) mostly showing unimodal distribution are shorten, indicating significant track-annealing. Thermal histories modeling based on the distribution of fission-track lengths combined with the regional geological data show that two rapid cooling phases occurred in the latest Jurassiceearly Cretaceous and the OligoceneeMiocene. Those new data together with previous published data show that the AFT ages become younger from the southwest to northeast in the western Bogda Mountain and its adjacent areas. The fission-track ages of the southwest area are relatively older (>100 Ma), recording the earlier rapid uplift phase during the late JurassiceCretaceous, while the ages in the north pied-mont of the Bogda Mountain (namely the northeast part) are younger (<60 Ma), mainly reflecting the later rapid uplift phase in the OligoceneeMiocene. The trend of younger AFT ages towards the northeast might be explained by post-Cretaceous large-scale crustal tilting towards the southwest. In the thrust fault-dominated northern limbs of the Bogda Mountain, AFT ages reveal a discontinuous pattern with age-jumps across the major fault zones, showing a possible strata tilting across each thrust faults due to the thrust ramps during the Cenozoic. The two rapid uplift stages might be related to the accretion and collision in the southern margin of the Asian continent during the late Jurassic and late Cenozoic, respectively.

  20. Erosion rates during rapid deglaciation in Icy Bay, Alaska

    Science.gov (United States)

    Koppes, MichèLe; Hallet, Bernard

    2006-06-01

    Contemporary glacial erosion rates based on sediment yields in southeast Alaska merit considerable attention because they are unsurpassed worldwide, and they significantly exceed long-term exhumation rates in the region. Two issues are likely to contribute to these high rates: contemporary sediment yields in fjords (1) have generally been overestimated by failing to account for the considerable input of subaerially derived material and (2) are exceptionally high because tidewater glaciers in southeast Alaska have been anomalously dynamic and erosive during the past century of rapid retreat. To investigate these influences and to quantify the rate at which Tyndall Glacier erodes its basin we present seismic data defining the volume of sediments in Taan Fjord, Icy Bay. We subtract the contribution of subaerially derived sediments from the fjord sediment package to determine the sediment yield directly from Tyndall Glacier during the most recent period of retreat: 1962-1999. Using a numerical model of proglacial glacimarine sedimentation, we then calculate the annual sediment yield from, and the corresponding erosion rate of, Tyndall Glacier during this period, which averages 28 ± 5 mma-1. A strong correlation emerges between glacial retreat rates and glacial sediment yields, implying that most contemporary sediment yield data from retreating tidewater glaciers may correspond to contemporary erosion rates that are a factor of 3.5 ± 1.5 higher than in the long term. Hence we estimate the long-term erosion rate for Tyndall Glacier to be 9 ± 2 mma-1.

  1. Metamorphic Tectonites and Differential Exhumation Reveal 3D Nature of Extension and Lower Crustal Flow in the Active Woodlark Rift, Papua New Guinea

    Science.gov (United States)

    Little, T. A.; Baldwin, S. L.; Fitzgerald, P. G.; Monteleone, B. D.; Peters, K. J.

    2004-12-01

    The D'Entrecasteaux Islands metamorphic core complexes (MCCs) occur in the Woodlark rift, a continental region where ˜200 km of extension since ˜6 Ma has been focused into a relatively small number of normal faults, some dipping at 12 mm/yr. To the east, an MCC on eastern Normanby Island has top-north footwall mylonites that dip gently SW and that were exhumed during the Pliocene as part of a northward progression of normal faulting that did not arrive at the offshore Moresby Seamount until ˜1.2 Ma (ODP Leg 180 site), relationships that suggest a rolling-hinge style uplift. Importantly, its detachment exposes no rocks deeper than blueschist-facies. Ductile deformation fabrics in the MCCs reveal patterns of lower crustal motion that can be evaluated against seafloor spreading-derived plate motions. Shear fabrics in MCCs closest to the Woodlark spreading ridges, including Normanby and Misima Islands are parallel to the NNE direction of 0.5-3.6 Ma Solomon Sea-Australia spreading. Farther west, lineations in the lower plates of the D'Entrecasteaux MCCs locally deflect ˜40-50° clockwise from this direction. This obliquity is interpreted to reflect inhomogeneous lower crustal extension to the west of the Woodlark spreading ridges. A rift corridor extending ˜100 km to the north of Goodenough and Fergusson Islands is defined by active normal faulting and subsidence of the Trobriand margin. We infer that a previously subducted, locally eclogite-bearing, slab of thinned Australian lower crust to the north of the islands is being pulled out from beneath this zone as it is being sinistrally sheared along its eastern edge. Today the rift zone steps ˜70 km south towards the Papuan Peninsula to define a right-step, an asymmetry that is enhanced by seafloor spreading east of ˜151.4° E. Published focal mechanisms suggest that N-S sinistral shear along the northern Woodlark rift is continuing. In central Normanby Island, ˜2 Ma andesites may have erupted along a transverse

  2. Zircon (U-Th)/He thermochronometry and modeling of Cenozoic exhumation of the West Spitsbergen Fold Belt: a HeFTy task

    Science.gov (United States)

    Barnes, Chris; Schneider, David; Majka, Jaroslaw; Lorenz, Henning; Kosminska, Karolina; Manecki, Maciej

    2015-04-01

    The West Spitsbergen Fold Belt (WSFB) is part of a ca. 55 Ma Eurekan deformation zone which trends N-S along the western margin of the Svalbard archipelago and is largely comprised of Meso- to Neoproterozoic metasediments and metavolcanics. (U-Th)/He thermochronometry is being conducted from three different regions within the fold belt to resolve the time-temperature history: Wedel Jarlsberg Land, Prins Karls Forland, and Sorkapp Land. Preliminary data obtained from Wedel Jarlsberg Land (amphibolite facies Eimfjellet Group and greenschist facies Sofiebogen Group) yield zircon (U-Th)/He (ZHe) ages indicative of Late Cretaceous to Early Paleogene cooling. It is apparent from the cooling ages that these Neoproterozoic rocks were >200°C before Eurekan deformation. Despite no clear trend between cooling age and grain size, the zircons exhibit a large range of eU values (51 to 826), viewed as a proxy for radiation damage, corresponding to a Gaussian distribution with age. Preliminary ZHe ages obtained from the Macnairrabbane unit of Prins Karls Forland suggests slightly younger cooling, as young as Late Eocene. HeFTy inversion models suggest the possibility that these rocks were at near-surface conditions through much of the Carboniferous and Permian as part of the Sorkapp-Hornsund High as a consequence of the Late Devonian Svalbardian Event. A moderate-temperature burial or heating event is therefore required to explain the Late Cretaceous /Early Paleogene ZHe cooling ages. With the current data, it is difficult to resolve whether this heating event was the result of pre-Eurekan sedimentation or syn-Eurekan over-thrusting. Nonetheless, the data strongly suggest fast cooling (and exhumation) through the He partial-retention zone during Eurekan tectonism, which may have commenced prior to 55 Ma. Similar thermochronometry results have been produced from Mesozoic rocks of the Sverdrup Basin exposed on Axel Heiberg and Ellesmere Islands of Canada; apatite fission-track and

  3. Rapid Prototyping Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The ARDEC Rapid Prototyping (RP) Laboratory was established in December 1992 to provide low cost RP capabilities to the ARDEC engineering community. The Stratasys,...

  4. Rapid Tooling via Stereolithography

    OpenAIRE

    Montgomery, Eva

    2006-01-01

    Approximately three years ago, composite stereolithography (SL) resins were introduced to the marketplace, offering performance features beyond what traditional SL resins could offer. In particular, the high heat deflection temperatures and high stiffness of these highly filled resins have opened the door to several new rapid prototyping (RP) applications, including wind tunnel test modelling and, more recently, rapid tooling.

  5. Contrast in stress-strain history during exhumation between high- and ultrahigh-pressure metamorphic units in the Western Alps: Microboudinage analysis of piemontite in metacherts

    Science.gov (United States)

    Omori, Yasutomo; Barresi, Antonello; Kimura, Nozomi; Okamoto, Atsushi; Masuda, Toshiaki

    2016-08-01

    Our analyses of microboudinage structures of piemontite grains embedded within six samples of metachert, one collected from an ultrahigh-pressure (UHP) metamorphic unit at Lago di Cignana in Italy of the Western Alps, and the other five from surrounding high-pressure (HP) metamorphic units in Italy and France, have revealed that the structures are all symmetrical in type, and were presumably produced in coaxial strain fields. Stress-strain analyses of the microboudinaged grains revealed significant contrasts in the stress and strain histories of the UHP and HP metamorphic units, with the differential stress recorded by the UHP sample being unequivocally lower than that recorded by the five HP samples. In addition, our analyses showed that the UHP sample underwent stress-relaxation during microboudinage, whereas the five HP samples did not. On the basis of these observations and analyses we discuss the mechanical decoupling of the UHP and HP units that led to different histories in differential stress between the units during exhumation of the Western Alps.

  6. Sedimentary response to orogenic exhumation in the northern rocky mountain basin and range province, flint creek basin, west-central Montana

    Science.gov (United States)

    Portner, R.A.; Hendrix, M.S.; Stalker, J.C.; Miggins, D.P.; Sheriff, S.D.

    2011-01-01

    Middle Eocene through Upper Miocene sedimentary and volcanic rocks of the Flint Creek basin in western Montana accumulated during a period of significant paleoclimatic change and extension across the northern Rocky Mountain Basin and Range province. Gravity modelling, borehole data, and geologic mapping from the Flint Creek basin indicate that subsidence was focused along an extensionally reactivated Sevier thrust fault, which accommodated up to 800 m of basin fill while relaying stress between the dextral transtensional Lewis and Clark lineament to the north and the Anaconda core complex to the south. Northwesterly paleocurrent indicators, foliated metamorphic lithics, 64 Ma (40Ar/39Ar) muscovite grains, and 76 Ma (U-Pb) zircons in a ca. 27 Ma arkosic sandstone are consistent with Oligocene exhumation and erosion of the Anaconda core complex. The core complex and volcanic and magmatic rocks in its hangingwall created an important drainage divide during the Paleogene shedding detritus to the NNW and ESE. Following a major period of Early Miocene tectonism and erosion, regional drainage networks were reorganized such that paleoflow in the Flint Creek basin flowed east into an internally drained saline lake system. Renewed tectonism during Middle to Late Miocene time reestablished a west-directed drainage that is recorded by fluvial strata within a Late Miocene paleovalley. These tectonic reorganizations and associated drainage divide explain observed discrepancies in provenance studies across the province. Regional correlation of unconformities and lithofacies mapping in the Flint Creek basin suggest that localized tectonism and relative base level fluctuations controlled lithostratigraphic architecture.

  7. Recrystallisation, phase mixing and strain localisation in peridotite during rapid extrusion of sub-arc mantle lithosphere

    Science.gov (United States)

    Czertowicz, T. A.; Toy, V. G.; Scott, J. M.

    2016-07-01

    The Anita Peridotite, in southwestern New Zealand, is a ∼1 × 20 km ultramafic massif that was rapidly extruded from beneath a Cretaceous arc within the 4 km wide mylonitic Anita Shear Zone. The peridotitic body contains a spectacular array of textures that preserve evidence for changing temperature, stress, and deformation mechanisms during the exhumation process. Olivine and orthopyroxene microstructures and lattice-preferred orientations (LPO) record a three-phase deformation history. Dislocation glide on the C- and E-type slip systems is recorded by coarse pre-mylonitised olivine grains, and occurred under hydrous conditions at T ∼650 °C, stress ∼200-700 MPa and strain rate ∼10-15 s-1, probably within hydrated sub-arc mantle lithosphere. Rare protomylonite pods record deformation by dislocation creep in porphyroclasts and dislocation-accommodated grain boundary sliding in the matrix on {0kl}[100] in olivine and (100)[001] in orthopyroxene, under conditions of T ∼730-770 °C, stress ∼52-700 MPa and strain rate ∼10-15 s-1. The massif, however, is dominated by mylonite and ultramylonite that wrap the protomylonite pods, comprising mostly fine-grained olivine neoblasts that lack internal distortions and have uniform LPOs. These textures indicate deformation occurred by grain-size sensitive (GSS) creep at T ∼650 °C, stress ∼69-137 MPa and strain rate ∼10-15 s-1, and thus during conditions of cooling and decreasing stress. GSS creep became more dominant with time, as the proportion of randomly-oriented neoblasts increased and formed interlinked networks that accommodated much of the strain. Grain boundary pinning allowed GSS creep to be maintained in polyphase regions, following mixing of olivine and orthopyroxene, which may have occurred by grain boundary transport in a fluid phase during a "creep cavitation" process. The results indicate that the Anita Peridotite recrystallised and underwent rheological weakening at a constant strain rate

  8. Mid-Cretaceous oblique rifting of West Antarctica: Emplacement and rapid cooling of the Fosdick Mountains migmatite-cored gneiss dome

    Science.gov (United States)

    McFadden, R. R.; Teyssier, C.; Siddoway, C. S.; Cosca, M. A.; Fanning, C. M.

    2015-09-01

    In Marie Byrd Land, West Antarctica, the Fosdick Mountains migmatite-cored gneiss dome was exhumed from mid- to lower middle crustal depths during the incipient stage of the West Antarctic Rift system in the mid-Cretaceous. Prior to and during exhumation, major crustal melting and deformation included transfer and emplacement of voluminous granitic material and numerous intrusions of mantle-derived diorite in dikes. A succession of melt- and magma-related structures formed at temperatures in excess of 665 ± 50 °C based on Ti-in-zircon thermometry. These record a transition from wrench to oblique extensional deformation that culminated in the development of the oblique South Fosdick Detachment zone. Solid-state fabrics within the detachment zone and overprinting brittle structures record translation of the detachment zone and dome to shallow levels. To determine the duration of exhumation and cooling, we sampled granite and gneisses at high spatial resolution for U-Pb zircon geochronology and 40Ar/39Ar hornblende and biotite thermochronology. U-Pb zircon crystallization ages for the youngest granites are 102 Ma. Three hornblende ages are 103 to 100 Ma and 12 biotite ages are 101 to 99 Ma. All overlap within uncertainty. The coincidence of zircon crystallization ages with 40Ar/39Ar cooling ages indicates cooling rates > 100 °C/m.y. that, when considered together with overprinting structures, indicates rapid exhumation of granite and migmatite from deep to shallow crustal levels within a transcurrent setting. Orientations of structures and age-constrained crosscutting relationships indicate counterclockwise rotation of stretching axes from oblique extension into nearly orthogonal extension with respect to the Marie Byrd Land margin. The rotation may be a result of localized extension arising from unroofing and arching of the Fosdick dome, extensional opening within a pull-apart zone, or changes in plate boundary configuration. The rapid tectonic and temperature

  9. SAP Sector Develops Rapidly

    Institute of Scientific and Technical Information of China (English)

    Zheng Chengwang

    2007-01-01

    @@ Stable demand growth internationally Super absorbent polymers (SAP) feature high water absorption, high water retention, rapid water absorption, great expanding power,strong thickening, strong anchoring and excellent elasticity.

  10. Rapid Lead Screening Test

    Science.gov (United States)

    ... Medical Procedures In Vitro Diagnostics Lab Tests Rapid Lead Screening Test Share Tweet Linkedin Pin it More ... reducing the need for a follow-up visit. Lead Risk Links Centers for Disease Control and Prevention ( ...

  11. Petrology of HP metamorphic veins in coesite-bearing eclogite from western Tianshan, China: Fluid processes and elemental mobility during exhumation in a cold subduction zone

    Science.gov (United States)

    Lü, Zeng; Zhang, Lifei; Du, Jinxue; Yang, Xin; Tian, Zuolin; Xia, Bin

    2012-04-01

    A petrological study was carried out for high pressure (HP) veins which cut through the host coesite-bearing eclogites at Habutengsu-Kebuerte in western Tianshan, China. The results place constraints on the origin and property of metamorphic fluids during subduction-zone metamorphism. Omphacite-, clinozoisite- and quartz-dominated veins occur on centimeter to meter scales within lens-shaped and layered eclogites, or cutting into the country rocks of garnet phengite schists. Coesite-bearing eclogites mainly consist of fibrous fine-grained omphacite and porphyroblastic garnet, with minor amounts of amphibole (mainly barroisite), clinozoisite, white mica (mainly paragonite) and rutile. The veins are pronouncedly coarse-grained compared to the host eclogites and commonly consist of quartz, clinozosite, rutile, white mica (phengite and paragonite) and garnet, with or without omphacite, titanite, apatite, carbonate (mainly dolomite) and glaucophane. Fluid inclusions are abundant in vein omphacite, titanite and apatite, but are rare in the equivalent minerals of host eclogites. Rounded vein garnets usually occur close to the sharp interface of vein and host eclogite. Omphacite in the veins is characterized by its euhedral form surrounded by quartz, or coarse bladed aggregates in contrast to the fibrous or patchy one, suggesting dynamic recrystallization in the host rocks. Omphacite in both veins and host eclogites has similar jadeite contents (Jd40-50), indicating formation at eclogite-facies metamorphic conditions. Vein phengite uniformly contains certain amounts of Ba with maximum BaO content of 3.16-4.25 wt.%, suggesting that Ba was mobilized during the exhumation of UHP rocks. Specific textures of vein minerals, such as the enclosure of magnesite (or calcite) in dolomite, rutile in titanite, and the occurrence of zoned Ba-rich phengite, indicate the chemical variability of channelized fluids over time. Based on Zr content in rutile and the presence of paragonite

  12. Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains

    Directory of Open Access Journals (Sweden)

    Wilfried Bauer

    2016-06-01

    Full Text Available The metamorphic basement of the Heimefrontfjella in western Dronning Maud Land (Antarctica forms the western margin of the major ca. 500 million year old East African/East Antarctic Orogen that resulted from the collision of East Antarctica and greater India with the African cratons. The boundary between the tectonothermally overprinted part of the orogen and its north-western foreland is marked by the subvertical Heimefront Shear Zone. North-west of the Heimefront Shear Zone, numerous low-angle dipping ductile thrust zones cut through the Mesoproterozoic basement. Petrographic studies, optical quartz c-axis analyses and x-ray texture goniometry of quartz-rich mylonites were used to reveal the conditions that prevailed during the deformation. Mineral assemblages in thrust mylonites show that they were formed under greenschist-facies conditions. Quartz microstructures are characteristic of the subgrain rotation regime and oblique quartz lattice preferred orientations are typical of simple shear-dominated deformation. In contrast, in the Heimefront Shear Zone, quartz textures indicate mainly flattening strain with a minor dextral rotational component. These quartz microstructures and lattice preferred orientations show signs of post-tectonic annealing following the tectonic exhumation. The spatial relation between the sub-vertical Heimefront Shear Zone and the low-angle thrusts can be explained as being the result of strain partitioning during transpressive deformation. The pure-shear component with a weak dextral strike-slip was accommodated by the Heimefront Shear Zone, whereas the north–north-west directed thrusts accommodate the simple shear component with a tectonic transport towards the foreland of the orogen.

  13. Apatite fission-track evidence for regional exhumation in the subtropical Eocene, block faulting, and localized fluid flow in east-central Alaska

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Bacon, Charles R.; O'Sullivan, Paul B.; Day, Warren C.

    2016-01-01

    The origin and antiquity of the subdued topography of the Yukon–Tanana Upland (YTU), the physiographic province between the Denali and Tintina faults, are unresolved questions in the geologic history of interior Alaska and adjacent Yukon. We present apatite fission-track (AFT) results for 33 samples from the 2300 km2 western Fortymile district in the YTU in Alaska and propose an exhumation model that is consistent with preservation of volcanic rocks in valleys that requires base level stability of several drainages since latest Cretaceous–Paleocene time. AFT thermochronology indicates widespread cooling below ∼110 °C at ∼56–47 Ma (early Eocene) and ∼44–36 Ma (middle Eocene). Samples with ∼33–27, ∼19, and ∼10 Ma AFT ages, obtained near a major northeast-trending fault zone, apparently reflect hydrothermal fluid flow. Uplift and erosion following ∼107 Ma magmatism exposed plutonic rocks to different extents in various crustal blocks by latest Cretaceous time. We interpret the Eocene AFT ages to suggest that higher elevations were eroded during the Paleogene subtropical climate of the subarctic, while base level remained essentially stable. Tertiary basins outboard of the YTU contain sediment that may account for the required >2 km of removed overburden that was not carried to the sea by the ancestral Yukon River system. We consider a climate driven explanation for the Eocene AFT ages to be most consistent with geologic constraints in concert with block faulting related to translation on the Denali and Tintina faults resulting from oblique subduction along the southern margin of Alaska.

  14. Tectonic control on rock uplift, exhumation, and topography above an oceanic ridge collision: Southern Patagonian Andes (47°S), Chile

    Science.gov (United States)

    Georgieva, Viktoria; Melnick, Daniel; Schildgen, Taylor F.; Ehlers, Todd A.; Lagabrielle, Yves; Enkelmann, Eva; Strecker, Manfred R.

    2016-06-01

    The subduction of bathymetric anomalies at convergent margins can profoundly affect subduction dynamics, magmatism, and the structural and geomorphic evolution of the overriding plate. The Northern Patagonian Icefield (NPI) is located east of the Chile Triple Junction at ~47°S, where the Chile Rise spreading center collides with South America. This region is characterized by an abrupt increase in summit elevations and relief that has been controversially debated in the context of geodynamic versus glacial erosion effects on topography. Here we present geomorphic, thermochronological, and structural data that document neotectonic activity along hitherto unrecognized faults along the flanks of the NPI. New apatite (U-Th)/He bedrock cooling ages suggest faulting since 2-3 Ma. We infer the northward translation of an ~140 km long fore-arc sliver -- the NPI block -- results from enhanced partitioning of oblique plate convergence due to the closely spaced collision of three successive segments of the Chile Rise. In this model, greater uplift occurs in the hanging wall of the Exploradores thrust at the northern leading edge of the NPI block, whereas the Cachet and Liquiñe-Ofqui dextral faults decouple the NPI block along its eastern and western flanks, respectively. Localized extension possibly occurs at its southern trailing edge along normal faults associated with margin-parallel extension, tectonic subsidence, and lower elevations along the Andean crest line. Our neotectonic model provides a novel explanation for the abrupt topographic variations inland of the Chile Triple Junction and emphasizes the fundamental effects of local tectonics on exhumation and topographic patterns in this glaciated landscape.

  15. Rapid middle Miocene extension and unroofing of the southern Ruby Mountains, Nevada

    Science.gov (United States)

    Colgan, Joseph P.; Howard, Keith A.; Fleck, Robert J.; Wooden, Joseph L.

    2010-01-01

    Paleozoic rocks in the northern Ruby Mountains were metamorphosed during Mesozoic crustal shortening and Cenozoic magmatism, but equivalent strata in the southern Ruby Mountains were never buried deeper than stratigraphic depths prior to exhumation in the footwall of a west dipping brittle normal fault. In the southern Ruby Mountains, Miocene sedimentary rocks in the hanging wall of this fault date from 15.2 to 11.6 Ma and contain abundant detritus from the Paleozoic section. Apatite fission track and (U-Th)/He samples of the Eocene Harrison Pass pluton record rapid cooling that peaked ca. 17–15 Ma, while apatite fission track data from Jurassic plutons east and west of the southern Ruby Mountains indicate near-surface temperatures (Ruby Mountains during slip on the west dipping brittle detachment between 17–16 and 10–12 Ma, followed by minor high-angle faulting. We interpret published Oligocene to early Miocene K-Ar biotite and zircon fission track dates from the Harrison Pass pluton to be partially reset rather than to directly record fault slip. Our new data, together with published data on the distribution and composition of Miocene basin fill, suggest that rapid middle Miocene slip took place on the west dipping brittle detachment that bounds the Ruby Mountains and East Humboldt Range for 150 km along strike. This fault was thus active during a period of rapid extension (ca. 17–15 to 12–10 Ma) documented widely across the northern Basin and Range Province.

  16. Rapid small lot manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Harrigan, R.W.

    1998-05-09

    The direct connection of information, captured in forms such as CAD databases, to the factory floor is enabling a revolution in manufacturing. Rapid response to very dynamic market conditions is becoming the norm rather than the exception. In order to provide economical rapid fabrication of small numbers of variable products, one must design with manufacturing constraints in mind. In addition, flexible manufacturing systems must be programmed automatically to reduce the time for product change over in the factory and eliminate human errors. Sensor based machine control is needed to adapt idealized, model based machine programs to uncontrolled variables such as the condition of raw materials and fabrication tolerances.

  17. Rapid microbiology - raising awareness.

    Science.gov (United States)

    Bailie, Jonathan

    2016-01-01

    A 'high-level overview' of some of the emerging rapid microbiology technologies designed to help healthcare engineering and infection control teams working in hospitals and other healthcare facilities more rapidly identify potentially hazardous levels of waterborne microorganisms in their water systems, enabling them to take prompt remedial action, and a look at the some of the 'pros and cons' of such testing techniques, was given by Nalco technical director, Howard Barnes, the vice-chair of the Legionella Control Association (LCA), at a recent LCA open day. HEJ editor, Jonathan Bailie, reports.

  18. Navigate the Digital Rapids

    Science.gov (United States)

    Lindsay, Julie; Davis, Vicki

    2010-01-01

    How can teachers teach digital citizenship when the digital landscape is changing so rapidly? How can teachers teach proper online social interactions when the students are outside their classroom and thus outside their control? Will encouraging students to engage in global collaborative environments land teachers in hot water? These are the…

  19. Evolution of amphibolite-facies structural features and boundary conditions for deformation during exhumation of high- and ultrahigh-pressure rocks, Nordøyane, Western Gneiss Region, Norway

    Science.gov (United States)

    Terry, Michael P.; Robinson, Peter

    2003-08-01

    Geologic mapping and structural analysis of Baltica basement and overlying thrust nappes have yielded a record of the late exhumation history of high-pressure rocks, where strain partitioning has preserved evidence for interpreting the evolution of late structural features. The earliest of these were extensional detachments juxtaposing eclogite-facies rocks against overlying amphibolite-facies rocks that show no evidence for eclogite-facies metamorphism. These early detachments are strongly overprinted and complexly folded, and they represent a phase of upper crustal extension that was active during continued convergence at deeper levels. Younger more localized mylonite zones formed synchronously with tubular, sheath, isoclinal, tight and open folding that shows a progression from WNW to ENE trends. The earliest mylonite zones, interpreted as originally subhorizontal, range in strike through a 20° angle from 110° to 90°. Later steeply dipping mylonite zones, formed under lower amphibolite-facies conditions, strike 75° and locally truncate earlier structures. The youngest mylonite zones, formed under lowest amphibolite conditions, strike 50° and truncate all earlier structures. Folds developed during this progression show the range in orientation from WNW to ENE reflected in the orientations of the mylonite zones that is interpreted to represent progressive evolution during top west shearing. These changes in orientation of the late structural features are interpreted to have been caused by changes in boundary conditions related to transtensional deformation during exhumation. L > S fabrics, absence of axial planar foliation, and chaotic orientations of axial surfaces of granulite to amphibolite-facies folds indicate formation in a constrictional strain field. This is also supported by estimates of the finite strain accumulated at ˜780°C and 45 km and similar observations by previous workers. Assuming a simple monoclinic deformation for transtension, strain

  20. Metamorphic and Ar/Ar geochronology constraints on the Alakeci shear zone: Implications for the extensional exhumation history of the northern Kazdag Massif, NW Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Bonev, N [Sofia University ' St. Kliment Ohridski' , Department of Geology and Paleontology, Sofia 1504 (Bulgaria); Beccaletto, L [BRGM Geological Survey/Geology of Sedimentary Basins, 45060 Orleans, Cedex 2 (France); Robyr, M [Geological Sciences Department, University of Texas, Austin, TX 787 12-0254 (United States); Monie, P [Geosciences, University of Montpellier 2, UMR 5243, 34095 Montpellier Cedex 5 (France)], E-mail: niki@gea.uni-sofia.bg

    2008-07-01

    from sillimanite core gneisses in the deeper structural levels to chlorite schists towards the top of the shear zone. These new data allow to precise the peak P-T conditions and the temporal evolution in the northern flank of the Kazdag Massif, where Late Oligocene extensional exhumation was assisted by NNE-directed ductile-brittle ASZ, which had operated from amphibolite to greenschist facies. At the regional scale, this tectono-metamorphic pattern is similar to those observed on other places of the north Aegean domain.

  1. Field and Microstructure Study of Transpressive Jogdadi shear zone near Ambaji, Aravalli- Delhi Mobile Belt, NW India and its tectonic implication on the exhumation of granulites.

    Science.gov (United States)

    Tiwari, Sudheer Kumar; Biswal, Tapas Kumar

    2016-04-01

    reduces in proportion and size. S fabric makes 13°- 40° angle with C-plane. From shear fabric NW oblique vergence has been interpreted. The Rigid Grain Net analysis of porphyroclast suggests mean kinematic vorticity number (Wm) range from 0.40 to 0.82. It suggests that this is transpressive shear zone. The mineral assemblages namely Qtz+ K- Flds+ Grt+ Bt in granite and Pla+ Hbl+ Bt in basic granulites suggests amphibolite facies of metamorphism during mylonitisation. Thus the exhumation of granulites is primarily accomplished through several parallel thrusts with Jogdadi shear zone which are transpressive in nature. Subsequently extensional condition and normal faulting have removed the cover rocks.

  2. Erraticity of rapidity gaps

    International Nuclear Information System (INIS)

    The use of rapidity gaps is proposed as a measure of the spatial pattern of an event. When the event multiplicity is low, the gaps between neighboring particles carry far more information about an event than multiplicity spikes, which may occur very rarely. Two moments of the gap distribution are suggested for characterizing an event. The fluctuations of those moments from event to event are then quantified by an entropy-like measure, which serves to describe erraticity. We use ECOMB to simulate the exclusive rapidity distribution of each event, from which the erraticity measures are calculated. The dependences of those measures on the order q of the moments provide single-parameter characterizations of erraticity. (c) 2000 The American Physical Society

  3. Rapid Detection of Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    David Perlin

    2005-08-14

    Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development

  4. New Rapid Spore Assay

    Science.gov (United States)

    Kminek, Gerhard; Conley, Catharine

    2012-07-01

    The presentation will detail approved Planetary Protection specifications for the Rapid Spore Assay for spacecraft components and subsystems. Outlined will be the research and studies on which the specifications were based. The research, funded by ESA and NASA/JPL, was conducted over a period of two years and was followed by limited cleanroom studies to assess the feasibility of this assay during spacecraft assembly.

  5. Tiber Personal Rapid Transit

    Directory of Open Access Journals (Sweden)

    Diego Carlo D'agostino

    2011-02-01

    Full Text Available The project “Tiber Personal Rapid Transit” have been presented by the author at the Rome City Vision Competition1 2010, an ideas competition, which challenges architects, engineers, designers, students and creatives individuals to develop visionary urban proposals with the intention of stimulating and supporting the contemporary city, in this case Rome. The Tiber PRT proposal tries to answer the competition questions with the definition of a provocative idea: a Personal Rapid transit System on the Tiber river banks. The project is located in the central section of the Tiber river and aims at the renewal of the river banks with the insertion of a Personal Rapid Transit infrastructure. The project area include the riverbank of Tiber from Rome Transtevere RFI station to Piazza del Popolo, an area where main touristic and leisure attractions are located. The intervention area is actually no used by the city users and residents and constitute itself a strong barrier in the heart of the historic city.

  6. Rapid frequency scan EPR.

    Science.gov (United States)

    Tseitlin, Mark; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2011-08-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x, y plane decays to baseline at the end of the scan, which typically is about 5T(2) after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5T(2). However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5T(2), even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B(1), periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation. PMID:21664848

  7. Right-Rapid-Rough

    Science.gov (United States)

    Lawrence, Craig

    2003-01-01

    IDEO (pronounced 'eye-dee-oh') is an international design, engineering, and innovation firm that has developed thousands of products and services for clients across a wide range of industries. Its process and culture attracted the attention of academics, businesses, and journalists around the world, and are the subject of a bestselling book, The Art of Innovation by Tom Kelley. One of the keys to IDEO's success is its use of prototyping as a tool for rapid innovation. This story covers some of IDEO's projects, and gives reasons for why they were successful.

  8. Rapid Frequency Scan EPR

    OpenAIRE

    Tseitlin, Mark; Rinard, George A.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2011-01-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x,y plane decays to baseline at the end of the scan, which typically is about 5 T2 after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5 T2. However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded...

  9. Rapidly progressive tabetic neurosyphilis

    Institute of Scientific and Technical Information of China (English)

    赖伟红; 薛华忠; 韩国柱

    2003-01-01

    Since the sexually transmitted diseases were recognized as a public health problem in China during the early 1980's, the incidence of syphilis has gradually increased. Though there have been case reports of clinical variants of neurosyphilis, including syphilitic cerebrospinal meningitis or meningomyelitis and meningovascular syphilis, occurring in different regions of China,1-3 tabes dorsalis or tabetic neurosyphilis has not yet been reported in China. Here, we report a young man with rapidly progressive tabetic neurosyphilis admitted to our hospital in October 1999.

  10. The Rapid Transient Surveyor

    CERN Document Server

    Baranec, Christoph; Wright, Shelley A; Tonry, John; Tully, R Brent; Szapudi, István; Takamiya, Marianne; Hunter, Lisa; Riddle, Reed; Chen, Shaojie; Chun, Mark

    2016-01-01

    The Rapid Transient Surveyor (RTS) is a proposed rapid-response, high-cadence adaptive optics (AO) facility for the UH 2.2-m telescope on Maunakea. RTS will uniquely address the need for high-acuity and sensitive near-infrared spectral follow-up observations of tens of thousands of objects in mere months by combining an excellent observing site, unmatched robotic observational efficiency, and an AO system that significantly increases both sensitivity and spatial resolving power. We will initially use RTS to obtain the infrared spectra of ~4,000 Type Ia supernovae identified by the Asteroid Terrestrial-Impact Last Alert System over a two year period that will be crucial to precisely measuring distances and mapping the distribution of dark matter in the z < 0.1 universe. RTS will comprise an upgraded version of the Robo-AO laser AO system and will respond quickly to target-of-opportunity events, minimizing the time between discovery and characterization. RTS will acquire simultaneous-multicolor images with a...

  11. Provenance of metasediments and Miocene exhumation history of the Lavrion Peninsula, South Attica, Greece: a combined structural, (U-Th)/He, and detrital zircon U-Pb study.

    Science.gov (United States)

    Seman, Spencer; Soukis, Konstantinos; Stockli, Daniel F.; Skourtsos, Emmanuel; Kranis, Haralambos; Lozios, Stylianos; Shin, Timothy

    2013-04-01

    the hanging wall of the SAD. For the Kamariza Unit data show Panafrican and Triassic input and reveal the maximum depositional age to be Triassic. The Lavrion Unit metasandstones exhibit a much wider range of detrital zircons and maximum depositional ages cluster in the late Jurassic to Cretaceous. Newly acquired (U-Th)/He data from the lower plate Kamariza Unit constrains late-stage brittle deformation on the SAD at 6-9 Ma, similar to data along strike of the WCDS on the islands of Kea and Serifos. Additionally, the Lavrion Unit record zircon (U-Th)/He ages in the middle Miocene, (16-12 Ma), similar to ages reported for the island of Kythnos. This data suggests two major episodes of exhumation along strike of the WCDS.

  12. Rapid automated nuclear chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, R.A.

    1979-05-31

    Rapid Automated Nuclear Chemistry (RANC) can be thought of as the Z-separation of Neutron-rich Isotopes by Automated Methods. The range of RANC studies of fission and its products is large. In a sense, the studies can be categorized into various energy ranges from the highest where the fission process and particle emission are considered, to low energies where nuclear dynamics are being explored. This paper presents a table which gives examples of current research using RANC on fission and fission products. The remainder of this text is divided into three parts. The first contains a discussion of the chemical methods available for the fission product elements, the second describes the major techniques, and in the last section, examples of recent results are discussed as illustrations of the use of RANC.

  13. JINR rapid communications

    International Nuclear Information System (INIS)

    The present collection of rapid communications from JINR, DUBNA, contains eight separate records on symmetry in modern physics (dedicated to the 100th anniversary of the birth of academician V.A.Fock), the double φ-meson production investigation on the Serpukhov accelerator, two-leptonic η-meson decays and SUSY without R parity, charge form factors and alpha-cluster internal structure of 12C, increasing of muon-track reconstruction efficiency in ME1/1 Dubna prototype for the CMS/LHC, study of photon-structure function F2γ in the reaction e+e- → e+e- + hadrons at LEP2, jets reconstruction possibility in pAu and AuAu interactions at STAR RHIC and high-vacuum nondispersable gas absorber

  14. JINR rapid communications

    International Nuclear Information System (INIS)

    The present collection of rapid communications from JINR, Dubna, contains twelve separate records on pseudoscalar form factor from inverse pion electroproduction and the first radial pion excitation, chiral and parity anomalies at finite temperature and density, the canonical form of an elastoplastic model of nuclear fusion, the peculiarities of the reactions of heavy and superheavy element synthesis within the dinuclear system concept, a study of the photon structure function F2γ in the reaction e+e-→e+e- + hadrons at LEP1 and LEP2, tritons for the study of the charge-exchange reactions with the LHE streamer chamber: status and some possibilities, nonlinear dynamics in nuclotron, current transformers and optical diagnostic monitor of nuclotron beam, the design features of the LHE JINR nuclotron internal target stations, a system of graphics digitization (SGD), numeric simulation of thermal treatment of metal surface by means of high current ion beam

  15. JINR rapid communications

    International Nuclear Information System (INIS)

    The present collection of rapid communications from JINR, Dubna, contains nine separate reports on effects arising from charged particles overcoming of the light velocity barrier, deformable templates for circle recognition, scintillation detectors for precise time measurements, atomic form factors and incoherent scattering functions of atoms and ions with the number of electrons N ≤ 10, experimental set-up ANOMALON for measurement of relativistic nuclear fragmentation cross sections, superconducting dipole magnet for ALICE dimuon arm spectrometer, analysis of transverse mass dependence of Bose-Einstein correlation radii using the DELPHI data, low-energy theorem in softly broken supersymmetry and study of the characteristics of particles in reactions π-, p, d, He, C + C with the total disintegration on carbon nucleus

  16. JINR rapid communications

    International Nuclear Information System (INIS)

    The present collection of rapid communications from JINR, Dubna, contains seven separate records on measurements of the total cross section difference ΔσL(np) at 1.59, 1.79, and 2.20 GeV, to the estimation of angular distributions of double charged spectator fragments in nucleus-nucleus interactions at superhigh energies, simulation dE/dx analysis results for silicon inner tracking system of ALICE set-up at LHC accelerator, high-multiplicity processes, triggering of high-multiplicity events using calorimetry, ORBIT-3.0 - a computer code for simulation and correction of the closed orbit and first turn in synchrotrons and determination of memory performance

  17. Higgsstrahlung at forward rapidities

    CERN Document Server

    Pasechnik, Roman; Potashnikova, Irina

    2014-01-01

    We discuss the inclusive and single diffractive heavy flavor (top and bottom) production in association with the Higgs boson at forward rapidities in proton-proton collisions at the LHC. The calculations are performed in the framework of the phenomenological dipole approach, which automatically accounts for the absorptive corrections induced by soft interactions, i.e. for the gap survival effects at the amplitude level. Major differential observables including the realistic ATLAS detector constraints are considered. The forward inclusive and diffractive Higgsstrahlung processes are generated essentially by excitation of the valence or sea quarks in the proton. The single diffractive Higgsstrahlung off top quarks is found to dominate compared to the loop-induced mechanism at sufficiently large Higgs boson transverse momenta. The Higgsstrahlung processes offer a direct and precise measurement of Higgs-top and, possibly, Higgs-bottom Yukawa couplings at the LHC, as well as the studies of the intrinsic heavy flav...

  18. Rapid Diagnosis of Malaria

    Directory of Open Access Journals (Sweden)

    Clinton K. Murray

    2009-01-01

    Full Text Available Malaria's global impact is expansive and includes the extremes of the healthcare system ranging from international travelers returning to nonendemic regions with tertiary referral medical care to residents in hyperendemic regions without access to medical care. Implementation of prompt and accurate diagnosis is needed to curb the expanding global impact of malaria associated with ever-increasing antimalarial drug resistance. Traditionally, malaria is diagnosed using clinical criteria and/or light microscopy even though both strategies are clearly inadequate in many healthcare settings. Hand held immunochromatographic rapid diagnostic tests (RDTs have been recognized as an ideal alternative method for diagnosing malaria. Numerous malaria RDTs have been developed and are widely available; however, an assortment of issues related to these products have become apparent. This review provides a summary of RDT including effectiveness and strategies to select the ideal RDT in varying healthcare settings.

  19. Rapid automated nuclear chemistry

    International Nuclear Information System (INIS)

    Rapid Automated Nuclear Chemistry (RANC) can be thought of as the Z-separation of Neutron-rich Isotopes by Automated Methods. The range of RANC studies of fission and its products is large. In a sense, the studies can be categorized into various energy ranges from the highest where the fission process and particle emission are considered, to low energies where nuclear dynamics are being explored. This paper presents a table which gives examples of current research using RANC on fission and fission products. The remainder of this text is divided into three parts. The first contains a discussion of the chemical methods available for the fission product elements, the second describes the major techniques, and in the last section, examples of recent results are discussed as illustrations of the use of RANC

  20. Rapid shallow breathing index.

    Science.gov (United States)

    Karthika, Manjush; Al Enezi, Farhan A; Pillai, Lalitha V; Arabi, Yaseen M

    2016-01-01

    Predicting successful liberation of patients from mechanical ventilation has been a focus of interest to clinicians practicing in intensive care. Various weaning indices have been investigated to identify an optimal weaning window. Among them, the rapid shallow breathing index (RSBI) has gained wide use due to its simple technique and avoidance of calculation of complex pulmonary mechanics. Since its first description, several modifications have been suggested, such as the serial measurements and the rate of change of RSBI, to further improve its predictive value. The objective of this paper is to review the utility of RSBI in predicting weaning success. In addition, the use of RSBI in specific patient populations and the reported modifications of RSBI technique that attempt to improve the utility of RSBI are also reviewed. PMID:27512505

  1. Rapid chemical separations

    CERN Document Server

    Trautmann, N

    1976-01-01

    A survey is given on the progress of fast chemical separation procedures during the last few years. Fast, discontinuous separation techniques are illustrated by a procedure for niobium. The use of such techniques for the chemical characterization of the heaviest known elements is described. Other rapid separation methods from aqueous solutions are summarized. The application of the high speed liquid chromatography to the separation of chemically similar elements is outlined. The use of the gas jet recoil transport method for nuclear reaction products and its combination with a continuous solvent extraction technique and with a thermochromatographic separation is presented. Different separation methods in the gas phase are briefly discussed and the attachment of a thermochromatographic technique to an on-line mass separator is shown. (45 refs).

  2. Rapid prototyping and time compression

    OpenAIRE

    Chatwin, Chris

    2000-01-01

    Rapid Prototyping - manufacture by layering processes: Stereolithography Selective Layer Sintering (SLS) Laminated Object Manufacture (LOM) Solid Ground Curing Small batch programmable rapid manufacture with lasers Micro-Engineering – Prototyping and Manufacture Additive - fabrication Subtractive – machining

  3. Rapid Refresh (RAP) [20 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental...

  4. Rapid Refresh (RAP) [13 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental...

  5. Rapid geophysical surveyor

    International Nuclear Information System (INIS)

    The Rapid Geophysical Surveyor (RGS) is a system designed to rapidly and economically collect closely-spaced geophysical data used for characterization of Department of Energy (DOE) waste sites. Geophysical surveys of waste sites are an important first step in the remediation and closure of these sites; especially older sties where historical records are inaccurate and survey benchmarks have changed due to refinements in coordinate controls and datum changes. Closely-spaced data are required to adequately differentiate pits, trenches, and soil vault rows whose edges may be only a few feet from each other. A prototype vehicle designed to collect magnetic field data was built at the Idaho national Engineering Laboratory (INEL) during the summer of 1992. The RGS was one of several projects funded by the Buried Waste Integrated Demonstration (BWID) program. This vehicle was demonstrated at the Subsurface Disposal Area (SDA) within the Radioactive Waste Management Complex (RWMC) on the INEL in September of 1992. Magnetic data were collected over two areas in the SDA, with a total survey area of about 1.7 acres. Data were collected at a nominal density of 2 1/2 inches along survey lines spaced 1 foot apart. Over 350,000 data points were collected over a 6 day period corresponding to about 185 man-days using conventional ground survey techniques. This report documents the design and demonstration of the RGS concept including the presentation of magnetic data collected at the SDA. The surveys were able to show pit and trench boundaries and determine details of their spatial orientation never before achieved

  6. The Rapid Transient Surveyor

    Science.gov (United States)

    Baranec, Christoph; Tonry, John; Wright, Shelley; Tully, R. Brent; Lu, Jessica R.; Takamiya, Marianne Y.; Hunter, Lisa

    2016-01-01

    The next decade of astronomy will be dominated by large area surveys (see the detailed discussion in the Astro-2010 Decadal survey and NRC's recent OIR System Report). Ground-based optical transient surveys, e.g., LSST, ZTF and ATLAS and space-based exoplanet, supernova, and lensing surveys such as TESS and WFIRST will join the Gaia all-sky astrometric survey in producing a flood of data that will enable leaps in our understanding of the universe. There is a critical need for further characterization of these discoveries through high angular resolution images, deeper images, spectra, or observations at different cadences or periods than the main surveys. Such follow-up characterization must be well matched to the particular surveys, and requires sufficient additional observing resources and time to cover the extensive number of targets.We describe plans for the Rapid Transient Surveyor (RTS), a permanently mounted, rapid-response, high-cadence facility for follow-up characterization of transient objects on the U. of Hawai'i 2.2-m telescope on Maunakea. RTS will comprise an improved robotic laser adaptive optics system, based on the prototype Robo-AO system (formerly at the Palomar 1.5-m and now at the Kitt Peak 2.2-m telescope), with simultaneous visible and near-infrared imagers as well as a near-infrared integral field spectrograph (R~100, λ = 850 - 1830 nm, 0.15″ spaxels, 8.7″×6.0″ FoV). RTS will achieve an acuity of ~0.07″ in visible wavelengths and < 0.16″ in the near infrared leading to an increase of the infrared point-source sensitivity against the sky background by a factor of ~9, crucial for efficient near-infrared spectroscopy.RTS will allow us to map the dark matter distribution in the z < 0.1 local universe with ten times better accuracy and precision than previous experiments. ATLAS will discover several thousand SNIae per year, measuring SNIa peak brightness, and decline rates, while RTS will measure reddening by dust, confirm SN type and

  7. Rapidly Evolving Giant Dermatofibroma

    Directory of Open Access Journals (Sweden)

    K. J. Lang

    2010-01-01

    Full Text Available Dermatofibroma, also known as “fibrous histiocytoma”, is a benign dermal or subcutaneous poorly circumscribed proliferation of spindle-shaped fibroblasts and macrophages in the dermis. Although it is commonly present as a brownish nodule the legs of females, it may also arise on the upper extremities, trunk, and rarely on the head. The exact pathogenesis is unclear. However, it is widely believed that the originating insult to the dermis is a folliculitis, an arthropod bite, or an unspecified initial inflammatory condition. Giant dermatofibromas of greater than 5 cm in diameter are rare, with only 22 cases reported in the literature. We present a case of a rapidly evolving pedunculated mass in the groin of a male patient. Histological examination confirmed this to be a giant dermatofibroma. Though this specimen cannot is not confirmed as such, the cellular subtype is sometimes present as a larger lesion with anecdotal reports of local recurrence and distant metastases. The clinical and radiological features which were somewhat suspicious of malignancy are considered in the context of the definitive pathological diagnosis of a benign lesion.

  8. Rapid Polymer Sequencer

    Science.gov (United States)

    Stolc, Viktor (Inventor); Brock, Matthew W (Inventor)

    2013-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal direction, or in a transverse direction, in the tip region, a polymer sequence is passed through the tip region, and a change in an electrical current signal is measured as each polymer component passes through the tip region. Each of the measured changes in electrical current signals is compared with a database of reference electrical change signals, with each reference signal corresponding to an identified polymer component, to identify the unknown polymer component with a reference polymer component. The nanopore preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  9. Rapid Evaporation of microbubbles

    Science.gov (United States)

    Gautam, Jitendra; Esmaeeli, Asghar

    2008-11-01

    When a liquid is heated to a temperature far above its boiling point, it evaporates abruptly. Boiling of liquid at high temperatures can be explosive and destructive, and poses a potential hazard for a host of industrial processes. Explosive boiling may occur if a cold and volatile liquid is brought into contact with a hot and non-volatile liquid, or if a liquid is superheated or depressurized rapidly. Such possibilities are realized, for example, in the depressurization of low boiling point liquefied natural gas (LNG) in the pipelines or storage tanks as a result of a leak. While boiling of highly heated liquids can be destructive at macroscale, the (nearly) instantaneous pace of the process and the release of large amount of kinetic energy make the phenomena extremely attractive at microscale where it is possible to utilize the released energy to derive micromechanical systems. For instance, there is currently a growing interest in micro-explosion of liquid for generation of micro bubbles for actuation purposes. The aim of the current study is to gain a fundamental understanding of the subject using direct numerical simulations. In particular, we seek to investigate the boundary between stable and unstable nucleus growth in terms of the degree of liquid superheat and to compare the dynamics of unstable and stable growth.

  10. Rapidly rotating red giants

    CERN Document Server

    Gehan, Charlotte; Michel, Eric

    2016-01-01

    Stellar oscillations give seismic information on the internal properties of stars. Red giants are targets of interest since they present mixed modes, which behave as pressure modes in the convective envelope and as gravity modes in the radiative core. Mixed modes thus directly probe red giant cores, and allow in particular the study of their mean core rotation. The high-quality data obtained by CoRoT and Kepler satellites represent an unprecedented perspective to obtain thousands of measurements of red giant core rotation, in order to improve our understanding of stellar physics in deep stellar interiors. We developed an automated method to obtain such core rotation measurements and validated it for stars on the red giant branch. In this work, we particularly focus on the specific application of this method to red giants having a rapid core rotation. They show complex spectra where it is tricky to disentangle rotational splittings from mixed-mode period spacings. We demonstrate that the method based on the id...

  11. Procedimentos em exumações para investigação de vínculo genético em ossos Exhumations procedures for investigating the genetic link in bones

    Directory of Open Access Journals (Sweden)

    João Arnaldo Damião Melki

    2001-08-01

    Full Text Available OBJETIVO: Identificar problemas técnicos nas exumações para pesquisa de DNA em ossos e propor soluções por meio de protocolo. MÉTODOS: Estudo prospectivo e qualitativo das exumações, procedendo cada etapa da perícia conforme proposto na literatura médico-legal. Foram realizadas dez exumações no período de 1995 a 1998, para coleta de restos humanos e extração do DNA, sendo sete de interesse civil e três, criminal. As dificuldades técnicas surgidas na execução desses procedimentos foram resolvidas a partir de alternativas estabelecidas. RESULTADOS: A escassez de informações úteis para a identificação do indivíduo, baseada em seus restos mortais, foi observada em todos os casos. As características morfológicas individuais contribuíram para a identificação em 50% dos casos. O auxílio dos familiares foi importante na revelação dessas características. Em três casos, foi indicado apenas o sexo e, em um, a idade. A falta de infra-estrutura dos cemitérios e de segurança policial dificultou o trabalho pericial. CONCLUSÕES: Para garantir a fidelidade do exame molecular do DNA é necessário identificar de quem são os restos mortais a serem exumados. Para a eficiência da perícia, é fundamental o uso de um protocolo que inclua, entre outras questões, as relativas a identificação, infra-estrutura e segurança pessoal dos peritos no local do exame.OBJECTIVE: To identify technical problems in exhumations performed for DNA detection in bones and to propose solutions through a protocol. METHODS: A prospective and qualitative study of exhumations was carried out according to the methods proposed in the medical legal literature. From 1995 to 1998, were performed 10 exhumations to collect human remains for DNA extraction. Of them, seven cases were of civil interest and three of criminal. Alternatives were sought to overcome technical difficulties found during the execution of these procedures. RESULTS: For all cases

  12. Rapid Robot Design Validation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies will create a comprehensive software infrastructure for rapid validation of robotic designs. The software will support push-button validation...

  13. Rapid Robot Design Validation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies will create a comprehensive software infrastructure for rapid validation of robot designs. The software will support push-button validation...

  14. Dimethyl Ether Sector Develops Rapidly

    Institute of Scientific and Technical Information of China (English)

    Zong Yangong

    2007-01-01

    @@ Rapid capacity expansion Dimethyl ether production in China has developed rapidly in recent years. The total capacity of dimethyl ether in China was only 31.8 thousand t/a in 2002, the output was around 20 thousand tons and the operating rate was 63%. The number of producers increased to over 30 in 2006.

  15. How Rapid is Rapid Prototyping? Analysis of ESPADON Programme Results

    Directory of Open Access Journals (Sweden)

    Ian D. Alston

    2003-05-01

    Full Text Available New methodologies, engineering processes, and support environments are beginning to emerge for embedded signal processing systems. The main objectives are to enable defence industry to field state-of-the-art products in less time and with lower costs, including retrofits and upgrades, based predominately on commercial off the shelf (COTS components and the model-year concept. One of the cornerstones of the new methodologies is the concept of rapid prototyping. This is the ability to rapidly and seamlessly move from functional design to the architectural design to the implementation, through automatic code generation tools, onto real-time COTS test beds. In this paper, we try to quantify the term “rapid” and provide results, the metrics, from two independent benchmarks, a radar and sonar beamforming application subset. The metrics show that the rapid prototyping process may be sixteen times faster than a conventional process.

  16. Wind influence on a coastal buoyant outflow

    Science.gov (United States)

    Whitney, Michael M.; Garvine, Richard W.

    2005-03-01

    This paper investigates the interplay between river discharge and winds in forcing coastal buoyant outflows. During light winds a plume influenced by the Earth's rotation will flow down shelf (in the direction of Kelvin wave propagation) as a slender buoyancy-driven coastal current. Downwelling favorable winds augment this down-shelf flow, narrow the plume, and mix the water column. Upwelling favorable winds drive currents that counter the buoyancy-driven flow, spread plume waters offshore, and rapidly mix buoyant waters. Two criteria are developed to assess the wind influence on a buoyant outflow. The wind strength index (Ws) determines whether a plume's along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. Wind influence on across-shelf plume structure is rated with a timescale (ttilt) for the isopycnal tilting caused by wind-driven Ekman circulation. These criteria are used to characterize wind influence on the Delaware Coastal Current and can be applied to other coastal buoyant outflows. The Delaware buoyant outflow is simulated for springtime high-river discharge conditions. Simulation results and Ws values reveal that the coastal current is buoyancy-driven most of the time (∣Ws∣ 1) several times during the high-discharge period. Strong upwelling events reverse the buoyant outflow; they constitute an important mechanism for transporting fresh water up shelf. Across-shelf plume structure is more sensitive to wind influence than the along-shelf flow. Values of ttilt indicate that moderate or strong winds persisting throughout a day can modify plume width significantly. Plume widening during upwelling events is accompanied by mixing that can erase the buoyant outflow.

  17. Rapid Multiplex Microbial Detector Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC, in collaboration with Lucigen, proposes a rapid nucleic acid-based detector for spaceflight water systems to enable simultaneous quantification of multiple...

  18. A Rapid Coliform Detector Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC, in collaboration with Lucigen, proposes a rapid genetic detector for spaceflight water systems to enable real-time detection of E-coli with minimal...

  19. Rapid deployment intrusion detection system

    International Nuclear Information System (INIS)

    A rapidly deployable security system is one that provides intrusion detection, assessment, communications, and annunciation capabilities; is easy to install and configure; can be rapidly deployed, and is reusable. A rapidly deployable intrusion detection system (RADIDS) has many potential applications within the DOE Complex: back-up protection for failed zones in a perimeter intrusion detection and assessment system, intrusion detection and assessment capabilities in temporary locations, protection of assets during Complex reconfiguration, and protection in hazardous locations, protection of assets during Complex reconfiguration, and protection in hazardous locations. Many DOE user-need documents have indicated an interest in a rapidly deployable intrusion detection system. The purpose of the RADIDS project is to design, develop, and implement such a system. 2 figs

  20. Economical Investigation of Rapid Prototyping

    OpenAIRE

    Péter Ficzere; Lajos Borbás; Ádám Török

    2013-01-01

    Usage of rapid prototyping gain developers, designers and engineers more time and consume less money and save more resources. In this article authors investigated the economic possibilities of rapid prototyping. In concurrent engineering, different tasks are tackled at the same time, and not necessarily in the usual order. Concurrent engineering is a method by which several teams within an organization work simultaneously to develop new products and allows more flexible approach. The concurre...

  1. Dilepton distributions at backward rapidities

    CERN Document Server

    Betemps, M A; De Oliveira, E G

    2006-01-01

    The dilepton production at backward rapidities in $pAu$ and $pp$ collisions at RHIC and LHC energies is investigated in the dipole approach. The results are shown through the nuclear modification ratio $R_{pA}$ considering the transverse momentum and rapidity spectra. The dilepton modification ratio presents interesting behavior at the backward rapidities once compared with the already known forward one, since it is related with large $x$ kinematical region that is being probed. The nuclear modification ratio rapidity spectrum in the dilepton production is strongly dependent on the Bjorken $x$ behavior of the nuclear structure function ratio $R_{F_{2}}=F_{2}^{A}/F_{2}^{p}$. The $R_{pA}$ transverse momentum dependence at backward rapidities is modified due to the large $x$ nuclear effects: at RHIC energies, for instance, the ratio $R_{pA}$ is reduced as $p_T$ increases, presenting oppositive behavior once compared with the forward one. It implies the dilepton production at backward rapidities should carry info...

  2. Rapid Manufacturing - auch mit SLM

    OpenAIRE

    Spierings, Adriaan; Levy, Gideon

    2009-01-01

    Rapid Manufacturing (RM) wurde als Schlagwort in der letzten Zeit insbesondere aus dem Bereich des Selective Laser Sintering (SLS) bekannt. In dieser inzwischen über 15-jährigen Technologieentwicklung wurden in den vergangenen Jahren bedeutende Fortschritte erzielt, die die Bauteileigenschaften nahe an die Anforderungen für End-Teile heran brachten. So ist das RM denn auch weniger aus der Sicht grösserer Losgrösse zu verstehen. Viel mehr bedeutet Rapid Manufacturing, dass die Bauteile nach ei...

  3. Knowledge Exchange Within the Rapid Climate Change Program (RAPID)

    Science.gov (United States)

    Wallace, C.; Srokosz, M.

    2008-12-01

    The Rapid Climate Change Program (RAPID) is a major UK-led science program investigating the susceptibility to and risk of abrupt change in the climate system, with a particular focus on the role of the Atlantic Meridional Overturning Circulation (AMOC). RAPID commenced in 2001, with initial funding to 2008 and has just entered its second phase - RAPID-WATCH - extending some aspects of the program until 2014. Scientifically, a key focus of the program has concerned the development and deployment of a continuous AMOC observing system, although the program has also supported research into a number of other aspects of rapid climate change, including paleo studies of past rapid changes, modeling of the past and future climate, and the development of methods with which to aid the quantification of future risks. Given the societal implications that abrupt climate change associated with the AMOC may have for the North Atlantic region, a major focus within the program has been the implementation of a Knowledge Exchange strategy with which to engage key decision and policy makers within the UK political and industrial sectors. This interaction is especially pertinent for those decision makers involved in the development of adaptive capacities that must incorporate resilience to so-called high-impact, low-probability class threats. We will summarize here the main aspects of our approach, outlining activities/methods used both to satisfy the obvious need to transfer key scientific findings from the program to users, but also in facilitating a return flow of knowledge which can be used by scientists to refine the impact and utility of scientific output. We will draw on particular experience gained from the program's involvement in i: personnel exchanges with central government departments; ii: interaction and co-operation with third party stakeholder organizations (e.g. the UK Climate Impacts Program); and iii: provision of written and oral briefings. Throughout, techniques

  4. Rapid Prototyping Enters Mainstream Manufacturing.

    Science.gov (United States)

    Winek, Gary

    1996-01-01

    Explains rapid prototyping, a process that uses computer-assisted design files to create a three-dimensional object automatically, speeding the industrial design process. Five commercially available systems and two emerging types--the 3-D printing process and repetitive masking and depositing--are described. (SK)

  5. Rapidly Deployed Modular Telemetry System

    Science.gov (United States)

    Varnavas, Kosta A. (Inventor); Sims, William Herbert, III (Inventor)

    2013-01-01

    The present invention is a telemetry system, and more specifically is a rapidly deployed modular telemetry apparatus which utilizes of SDR technology and the FPGA programming capability to reduce the number of hardware components and programming required to deploy a telemetry system.

  6. Rapid thermal processing of semiconductors

    CERN Document Server

    Borisenko, Victor E

    1997-01-01

    Rapid thermal processing has contributed to the development of single wafer cluster processing tools and other innovations in integrated circuit manufacturing environments Borisenko and Hesketh review theoretical and experimental progress in the field, discussing a wide range of materials, processes, and conditions They thoroughly cover the work of international investigators in the field

  7. Evolution of rapid nerve conduction.

    Science.gov (United States)

    Castelfranco, Ann M; Hartline, Daniel K

    2016-06-15

    Rapid conduction of nerve impulses is a priority for organisms needing to react quickly to events in their environment. While myelin may be viewed as the crowning innovation bringing about rapid conduction, the evolution of rapid communication mechanisms, including those refined and enhanced in the evolution of myelin, has much deeper roots. In this review, a sequence is traced starting with diffusional communication, followed by transport-facilitated communication, the rise of electrical signaling modalities, the invention of voltage-gated channels and "all-or-none" impulses, the emergence of elongate nerve axons specialized for communication and their fine-tuning to enhance impulse conduction speeds. Finally within the evolution of myelin itself, several innovations have arisen and have been interactively refined for speed enhancement, including the addition and sealing of layers, their limitation by space availability, and the optimization of key parameters: channel density, lengths of exposed nodes and lengths of internodes. We finish by suggesting several design principles that appear to govern the evolution of rapid conduction. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26879248

  8. Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska.

    Science.gov (United States)

    Gulick, Sean P S; Jaeger, John M; Mix, Alan C; Asahi, Hirofumi; Bahlburg, Heinrich; Belanger, Christina L; Berbel, Glaucia B B; Childress, Laurel; Cowan, Ellen; Drab, Laureen; Forwick, Matthias; Fukumura, Akemi; Ge, Shulan; Gupta, Shyam; Kioka, Arata; Konno, Susumu; LeVay, Leah J; März, Christian; Matsuzaki, Kenji M; McClymont, Erin L; Moy, Chris; Müller, Juliane; Nakamura, Atsunori; Ojima, Takanori; Ribeiro, Fabiana R; Ridgway, Kenneth D; Romero, Oscar E; Slagle, Angela L; Stoner, Joseph S; St-Onge, Guillaume; Suto, Itsuki; Walczak, Maureen D; Worthington, Lindsay L; Bailey, Ian; Enkelmann, Eva; Reece, Robert; Swartz, John M

    2015-12-01

    Erosion, sediment production, and routing on a tectonically active continental margin reflect both tectonic and climatic processes; partitioning the relative importance of these processes remains controversial. Gulf of Alaska contains a preserved sedimentary record of the Yakutat Terrane collision with North America. Because tectonic convergence in the coastal St. Elias orogen has been roughly constant for 6 My, variations in its eroded sediments preserved in the offshore Surveyor Fan constrain a budget of tectonic material influx, erosion, and sediment output. Seismically imaged sediment volumes calibrated with chronologies derived from Integrated Ocean Drilling Program boreholes show that erosion accelerated in response to Northern Hemisphere glacial intensification (∼ 2.7 Ma) and that the 900-km-long Surveyor Channel inception appears to correlate with this event. However, tectonic influx exceeded integrated sediment efflux over the interval 2.8-1.2 Ma. Volumetric erosion accelerated following the onset of quasi-periodic (∼ 100-ky) glacial cycles in the mid-Pleistocene climate transition (1.2-0.7 Ma). Since then, erosion and transport of material out of the orogen has outpaced tectonic influx by 50-80%. Such a rapid net mass loss explains apparent increases in exhumation rates inferred onshore from exposure dates and mapped out-of-sequence fault patterns. The 1.2-My mass budget imbalance must relax back toward equilibrium in balance with tectonic influx over the timescale of orogenic wedge response (millions of years). The St. Elias Range provides a key example of how active orogenic systems respond to transient mass fluxes, and of the possible influence of climate-driven erosive processes that diverge from equilibrium on the million-year scale.

  9. Reaction zone between pre-UHP titanite and host rock: insights into fluid-rock interaction and deformation mechanisms during exhumation of deeply subducted continental crust (Dabie Shan UHP unit, China)

    Science.gov (United States)

    Wawrzenitz, N.; Romer, R. L.; Grasemann, B.; Morales, L. F. G.

    2012-04-01

    Exhumed crustal UHP rocks may occur as relict blocks in strongly metasomatized matrix rocks. Due to variations in competence between the mm to km sized blocks and their ductile matrix, the largely undeformed blocks may preserve the pre-subduction and the prograde history, whereas the matrix rocks have been ductilely deformed to high magnitudes and record successive stages of deformation. The reaction zones between blocks and matrix, however, provide insights into the fluid-rock interaction, deformation and the deformation mechanisms active during the exhumation of deeply subducted continental crust in the subduction channel. We investigate a titanite megacryst (3 cm in diameter) in a calc-silicate marble from the UHP unit in the Dabie Shan, China. The core of the titanite megacryst grew prograde during subduction. Its U-Pb system remained closed and yields a maximum age for UHP metamorphism. Sr and Nd isotope compositions in the core demonstrate that the titanite megacryst precipitated from a homogeneous fluid source. During metamorphism in the subduction zone, infiltration of external fluids resulted first in Sr-loss from the marbles and then introduction of Sr with unusually low 87Sr/86S values (Romer et al., 2003), leading to the contrasting 87Sr/86Sr values in the titanite megacryst and the hosting UHP marbles (Wawrzenitz et al., 2006). Related to deformation in the calc-silicate marble matrix, the rim of the titanite megacryst has been replaced during the following dissolution-precipitation reactions: (i) Pseudomorphic replacement of the old titanite megacryst by coupled dissolution-reprecipitation. Fluid migrated into the old grain producing a sharp boundary of the replacement front. (ii) New small titanite grains grew with their long axes parallel to the foliation of the marble matrix, reflecting the activation of dissolution precipitation creep. In the matrix, the foliation is defined by the orientation of the basal planes of phengitic white mica. The new

  10. Rapid and sustained cost management

    International Nuclear Information System (INIS)

    Accenture helps clients develop comprehensive, process-driven strategies for rapid and sustained cost management that leverage deep insights and analytics. This approach enables companies to gain operating cost advantages by rationalizing, simplifying and automating current operating capabilities. It drives structural cost advantages by optimizing business mix, capital structure, organizational structure and geographic presence. This paper discussed how successful companies achieve high performance during times of economic turmoil. It also discussed the value of the winner's strategy in terms of rapid and sustained cost management (RSCM). It discussed how Accenture operates and its leveraged capabilities, improved efficiency, margins and cash flow while maintaining customer service levels. Building structural advantage and the Accenture difference were also discussed. It was concluded that RSCM is one vital way that Accenture can help companies achieve success. 4 figs

  11. Rapid Sampling from Sealed Containers

    International Nuclear Information System (INIS)

    The authors have developed several different types of tools for sampling from sealed containers. These tools allow the user to rapidly drill into a closed container, extract a sample of its contents (gas, liquid, or free-flowing powder), and permanently reseal the point of entry. This is accomplished without exposing the user or the environment to the container contents, even while drilling. The entire process is completed in less than 15 seconds for a 55 gallon drum. Almost any kind of container can be sampled (regardless of the materials) with wall thicknesses up to 1.3 cm and internal pressures up to 8 atm. Samples can be taken from the top, sides, or bottom of a container. The sampling tools are inexpensive, small, and easy to use. They work with any battery-powered hand drill. This allows considerable safety, speed, flexibility, and maneuverability. The tools also permit the user to rapidly attach plumbing, a pressure relief valve, alarms, or other instrumentation to a container. Possible applications include drum venting, liquid transfer, container flushing, waste characterization, monitoring, sampling for archival or quality control purposes, emergency sampling by rapid response teams, counter-terrorism, non-proliferation and treaty verification, and use by law enforcement personnel during drug or environmental raids

  12. Rapid diagnosis of bacteric meningitis

    Directory of Open Access Journals (Sweden)

    Sara Giordana Rimoldi

    2010-09-01

    Full Text Available Gram stain and bacterial antigen detection are economic and rapid tests for the identification of the bacteria in cerebrospinal fluid (CSF for the diagnosis of meningitis. Even if culture is the gold standard of these diagnosis, it requires long time (growth time. The purpose of our study was to compare in the laboratory diagnosis of meningitis real time PCR (Eurospital, Italy. with standard methods. Samples were collected in patients referred to L. Sacco Universital Hospital (range of age: 16 to 70 years from September 2008 to July 2009. 9 out of 130 CFS samples investigated were positive in PCR but they produced different results to the other methods used.

  13. Rapidly Adaptable Instrumentation Tester (RAIT)

    International Nuclear Information System (INIS)

    Emerging technologies in the field of ''Test ampersand Measurement'' have recently enabled the development of the Rapidly Adaptable Instrumentation Tester (RAIT). Based on software developed with LabVIEW, the RAIT design enables quick reconfiguration to test and calibrate a wide variety of telemetry systems. The consequences of inadequate testing could be devastating if a telemetry system were to fail during an expensive flight mission. Supporting both open-bench testing as well as automated test sequences, the RAIT has significantly lowered total time required to test and calibrate a system. This has resulted in an overall lower per unit testing cost than has been achievable in the past

  14. Rapidly rotating neutron star progenitors

    CERN Document Server

    Postnov, K A; Kolesnikov, D A; Popov, S B; Porayko, N K

    2016-01-01

    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In the present paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, $\\tau_c$. The validity of this approach is checked by direct MESA calculations ...

  15. Rapidly rotating neutron star progenitors

    Science.gov (United States)

    Postnov, K. A.; Kuranov, A. G.; Kolesnikov, D. A.; Popov, S. B.; Porayko, N. K.

    2016-08-01

    Rotating proto-neutron stars can be important sources of gravitational waves to be searched for by present-day and future interferometric detectors. It was demonstrated by Imshennik that in extreme cases the rapid rotation of a collapsing stellar core may lead to fission and formation of a binary proto-neutron star which subsequently merges due to gravitational wave emission. In the present paper, we show that such dynamically unstable collapsing stellar cores may be the product of a former merger process of two stellar cores in a common envelope. We applied population synthesis calculations to assess the expected fraction of such rapidly rotating stellar cores which may lead to fission and formation of a pair of proto-neutron stars. We have used the BSE population synthesis code supplemented with a new treatment of stellar core rotation during the evolution via effective core-envelope coupling, characterized by the coupling time, τc. The validity of this approach is checked by direct MESA calculations of the evolution of a rotating 15 M⊙ star. From comparison of the calculated spin distribution of young neutron stars with the observed one, reported by Popov and Turolla, we infer the value τc ≃ 5 × 105 years. We show that merging of stellar cores in common envelopes can lead to collapses with dynamically unstable proto-neutron stars, with their formation rate being ˜0.1 - 1% of the total core collapses, depending on the common envelope efficiency.

  16. Rapid ISS Power Availability Simulator

    Science.gov (United States)

    Downing, Nicholas

    2011-01-01

    The ISS (International Space Station) Power Resource Officers (PROs) needed a tool to automate the calculation of thousands of ISS power availability simulations used to generate power constraint matrices. Each matrix contains 864 cells, and each cell represents a single power simulation that must be run. The tools available to the flight controllers were very operator intensive and not conducive to rapidly running the thousands of simulations necessary to generate the power constraint data. SOLAR is a Java-based tool that leverages commercial-off-the-shelf software (Satellite Toolkit) and an existing in-house ISS EPS model (SPEED) to rapidly perform thousands of power availability simulations. SOLAR has a very modular architecture and consists of a series of plug-ins that are loosely coupled. The modular architecture of the software allows for the easy replacement of the ISS power system model simulator, re-use of the Satellite Toolkit integration code, and separation of the user interface from the core logic. Satellite Toolkit (STK) is used to generate ISS eclipse and insulation times, solar beta angle, position of the solar arrays over time, and the amount of shadowing on the solar arrays, which is then provided to SPEED to calculate power generation forecasts. The power planning turn-around time is reduced from three months to two weeks (83-percent decrease) using SOLAR, and the amount of PRO power planning support effort is reduced by an estimated 30 percent.

  17. KEPLER RAPIDLY ROTATING GIANT STARS

    Energy Technology Data Exchange (ETDEWEB)

    Costa, A. D.; Martins, B. L. Canto; Bravo, J. P.; Paz-Chinchón, F.; Chagas, M. L. das; Leão, I. C.; Oliveira, G. Pereira de; Silva, R. Rodrigues da; Roque, S.; Oliveira, L. L. A. de; Silva, D. Freire da; De Medeiros, J. R., E-mail: renan@dfte.ufrn.br [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitário, Natal RN (Brazil)

    2015-07-10

    Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of substellar companions by their hosting stars. In the present Letter, we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time, the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting a very short rotation period with values ranging from 13 to 55 days. This finding points to remarkable surface rotation rates, up to 18 times the rotation of the Sun. These giants are combined with six others recently listed in the literature for mid-infrared (IR) diagnostics based on Wide-field Infrared Survey Explorer information, from which a trend for an IR excess is revealed for at least one-half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

  18. Kepler rapidly rotating giant stars

    CERN Document Server

    Costa, A D; Bravo, J P; Paz-Chinchón, F; Chagas, M L das; Leão, I C; de Oliveira, G Pereira; da Silva, R Rodrigues; Roque, S; de Oliveira, L L A; da Silva, D Freire; De Medeiros, J R

    2015-01-01

    Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of sub-stellar companions by their hosting stars. In the present letter we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting very short rotation period with values ranging from 13 to 55 days. This finding points for remarkable surface rotation rates, up to 18 times the Sun rotation. These giants are combined with 6 other recently listed in the literature for mid-IR diagnostic based on WISE information, from which a trend for an infrared excess is revealed for at least a half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

  19. Rapid self-healing hydrogels

    Science.gov (United States)

    Phadke, Ameya; Zhang, Chao; Arman, Bedri; Hsu, Cheng-Chih; Mashelkar, Raghunath A.; Lele, Ashish K.; Tauber, Michael J.; Arya, Gaurav; Varghese, Shyni

    2012-01-01

    Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hydrogel network with flexible-pendant side chains carrying an optimal balance of hydrophilic and hydrophobic moieties that allows the side chains to mediate hydrogen bonds across the hydrogel interfaces with minimal steric hindrance and hydrophobic collapse. The self-healing reported here is rapid, occurring within seconds of the insertion of a crack into the hydrogel or juxtaposition of two separate hydrogel pieces. The healing is reversible and can be switched on and off via changes in pH, allowing external control over the healing process. Moreover, the hydrogels can sustain multiple cycles of healing and separation without compromising their mechanical properties and healing kinetics. Beyond revealing how secondary interactions could be harnessed to introduce new functions to chemically cross-linked polymeric systems, we also demonstrate various potential applications of such easy-to-synthesize, smart, self-healing hydrogels. PMID:22392977

  20. Rapidly Developing Toxic Epidermal Necrolysis

    Directory of Open Access Journals (Sweden)

    Viktoria Oline Barrios Poulsen

    2013-01-01

    Full Text Available Severe cutaneous reactions with potentially fatal outcomes can have many different causes. The Stevens-Johnson syndrome (SJS and toxic epidermal necrolysis (TEN are rare. They are characterized by a low incidence but high mortality, and drugs are most commonly implicated. Urgent active therapy is required. Prompt recognition and withdrawal of suspect drug and rapid intervention can result in favourable outcome. No further international guidelines for treatment exist, and much of the treatment relies on old or experimental concepts with no scientific evidence. We report on a 54-year-old man experiencing rapidly developing drug-induced severe TEN and presented multiorgan failure involving the respiratory and circulatory system, coagulopathy, and renal insufficiency. Detachment counted 30% of total body surface area (TBSA. SCORTEN = 5, indicating a mortality rate >90%. The patient was sedated and mechanically ventilated, supported with fluids and inotropes to maintain a stable circulation. Component therapy was guided by thromboelastography (TEG. The patient received plasmapheresis, and shock reversal treatment was initiated. He was transferred to a specialized intensive care burn unit within 24 hours from admittance. The initial care was continued, and hemodialysis was started. Pulmonary, circulatory, and renal sequelae resolved with intensive care, and re-epithelialization progressed slowly. The patient was discharged home on hospital day 19.

  1. Late Paleozoic onset of subduction and exhumation at the western margin of Gondwana (Chilenia Terrane): Counterclockwise P-T paths and timing of metamorphism of deep-seated garnet-mica schist and amphibolite of Punta Sirena, Coastal Accretionary Complex, central Chile (34° S)

    Science.gov (United States)

    Hyppolito, T.; García-Casco, A.; Juliani, C.; Meira, V. T.; Hall, C.

    2014-10-01

    In this study, the Paleozoic albite-epidote-amphibolite occurring as meter-sized intercalations within garnet-mica schist at Punta Sirena beach (Pichilemu region, central Chile) is characterized for the first time. These rocks constitute an unusual exposure of subduction-related rocks within the Paleozoic Coastal Accretionary Complex of central Chile. Whereas high pressure (HP) greenschist and cofacial metasediments are the predominant rocks forming the regional metamorphic basement, the garnet-mica schist and amphibolite yield higher P-T conditions (albite-epidote amphibolite facies) and an older metamorphic age. Combining detailed mineral chemistry and textural information, P-T calculations and Ar-Ar ages, including previously published material from the Paleozoic Accretionary Complex of central Chile, we show that the garnet-mica schist and associated amphibolite (locally retrograded to greenschist) are vestiges of the earliest subducted material now forming exotic bodies within the younger HP units of the paleo-accretionary wedge. These rocks are interpreted as having been formed during the onset of subduction at the southwestern margin of Gondwana. However, we show that the garnet-mica schist formed at a slightly greater depth (ca. 40 km) than the amphibolite (ca. 30 km) along the same hot-subduction gradient developed during the onset of subduction. Both lithotypes reached their peak-P conditions at ca. 335-330 Ma and underwent near-isobaric cooling followed by cooling and decompression (i.e., counterclockwise P-T paths). The forced return flow of the garnet-mica schist from the subduction channel started at ca. 320 Ma and triggered the exhumation of fragments of shallower accreted oceanic crust (amphibolite). Cores of phengite (garnet-mica schist) and amphibole (amphibolite) grains have similar chemical compositions in both the S1 and S2 domains, indicating rotation of these grains during the transposition of the burial-related (prograde peak-T) foliation S1

  2. Single-Degenerate Type Ia Supernovae Are Preferentially Overluminous

    CERN Document Server

    Fisher, Robert

    2015-01-01

    Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly-accreting Chandrasekhar mass white dwarfs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass white dwarfs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are gen...

  3. Moved by a Rapid Transit

    Science.gov (United States)

    Bueter, C.

    2013-04-01

    Enticing by virtue of its predictability, historical utility, and spectacle, the transit of Venus is a niche event among astronomical phenomena. Though the value of a transit for scientific purposes is now diminished, the brief appearance of Venus silhouetted against the background of the Sun in 2004 moved the artistic community to celebrate the rare alignment. Artists of all ages combined old traditions with fresh technology to create a 21st-century tapestry of music, sculpture, paintings, glasswork, quilts, sky shows, and digital imagery. A full catalog of transit-related art generated over the centuries would feature the sampling of entries presented here and at the Moved by a Rapid Transit website.

  4. Rapid world modelling for robotics

    International Nuclear Information System (INIS)

    The ability to use an interactive world model, whether it is for robotics simulation or most other virtual graphical environments, relies on the users ability to create an accurate world model. Typically this is a tedious process, requiring many hours to create 3-D CAD models of the surfaces within a workspace. The goal of this ongoing project is to develop usable methods to rapidly build world models of real world workspaces. This brings structure to an unstructured environment and allows graphical based robotics control to be accomplished in a reasonable time frame when traditional CAD modelling is not enough. To accomplish this, 3D range sensors are deployed to capture surface data within the workspace. This data is then transformed into surface maps, or models. A 3D world model of the workspace is built quickly and accurately, without ever having to put people in the environment

  5. Rapid Adaptation in Digital Transformation

    DEFF Research Database (Denmark)

    Hansen, Anne Mette; Kræmmergaard, Pernille; Mathiassen, Lars

    2011-01-01

    In today’s highly dynamic environments, organizational leaders need to quickly adapt existing approaches to digital transformation. However, without a shared mindset between IS and business leaders, it is difficult to adopt new approaches in response to changes in the competitive and technology...... landscape. In this article, we share insights gained from two public sector organizations in which IS and business leaders used the Participatory Process Model (PPM) designed by the authors to share their assumptions about IS leadership, challenge existing IT strategies and collaboration patterns and adapt...... the organization’s digitization approach. We demonstrate in detail how the leaders within these two organizations were engaged and offer recommendations for how other organizations can use the PPM to rapidly adapt their approaches to digital transformation through more effective IS leadership roles....

  6. Rapid adaptation to climate change.

    Science.gov (United States)

    Hancock, Angela M

    2016-08-01

    In recent years, amid growing concerns that changing climate is affecting species distributions and ecosystems, predicting responses to rapid environmental change has become a major goal. In this issue, Franks and colleagues take a first step towards this objective (Franks et al. 2016). They examine genomewide signatures of selection in populations of Brassica rapa after a severe multiyear drought. Together with other authors, Franks had previously shown that flowering time was reduced after this particular drought and that the reduction was genetically encoded. Now, the authors have sequenced previously stored samples to compare allele frequencies before and after the drought and identify the loci with the most extreme shifts in frequencies. The loci they identify largely differ between populations, suggesting that different genetic variants may be responsible for reduction in flowering time in the two populations. PMID:27463237

  7. Silicone:Worries behind Rapid Growth

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Rapid consumption growth Silicone's extensive application scope, sustained production growth and constant technology improvements have benefited from the rapid development of China's economy overall, and particularly the boom in the manufacturing sector.

  8. U-Pb isotopic compositions of the ultrahigh pressure metamorphic (UHPM) rocks from Shuanghe and gneisses from Northern Dabie zone in the Dabie Mountains,central China: Constraint on the exhumation mechanism of UHPM rocks

    Institute of Scientific and Technical Information of China (English)

    李曙光; 黄方; 周红英; 李惠民

    2003-01-01

    The U-Pb isotopic study of the ultrahigh pressure metamorphic (UHPM) rocks and gneisses from the Dabie Mountains shows that the UHPM rocks exposed in the Southern Dabie zone have relatively low Pb contents (most 0.1), and a large variation of Pb isotopic ratios with relatively high radiogenic Pb (206Pb/204Pb = 17.026-20.781). Their low Pb contents could be the result of Pb loss caused by fluid expulsion during continental subduction, while their high radiogenic Pb values can be explained by the mixing of the upper crust Pb and the mantle Pb. In contrast, the gneisses exposed in the Northern Dabie zone have higher Pb contents (most > 4×10?6), lower U/Pb ratios (< 0.07), and lower Pb isotopic ratios (206Pb/204Pb = 15.799-17.204), which are similar to those of the Mesozoic granites developed in both Northern and Southern Dabie zones. It is suggested that the Northern Dabie zone may have experienced a smaller fluid expulsion and Pb loss during the continental subduction, and their Pb isotopic compositions could be explained by the mixing of the lower crust Pb and the mantle Pb. Their initial Pb isotope ratios at 230 Ma suggest that the U/Pb ratios of the UHPM rocks in the Southern Dabie zone are higher than those of the gneisses in the Northern Dabie zone in a long period of time before the continental subduction. The above observations suggest that the protoliths of the UHPM rocks in the Southern Dabie zone are upper crustal rocks in the subducted continental crust, while the gneisses in the Northern Dabie zone have the middle-lower crust features. Based on these observations, a model for the exhumation of UHPM rocks is proposed, i.e. the detachment between the upper crust and lower crust in the subducted continental crust could have occurred during subduction, thus the subducted upper crust was uplifted by buoyancy and moved southward along the thrust.

  9. Rapid typing of Coxiella burnetii.

    Directory of Open Access Journals (Sweden)

    Heidie M Hornstra

    Full Text Available Coxiella burnetii has the potential to cause serious disease and is highly prevalent in the environment. Despite this, epidemiological data are sparse and isolate collections are typically small, rare, and difficult to share among laboratories as this pathogen is governed by select agent rules and fastidious to culture. With the advent of whole genome sequencing, some of this knowledge gap has been overcome by the development of genotyping schemes, however many of these methods are cumbersome and not readily transferable between institutions. As comparisons of the few existing collections can dramatically increase our knowledge of the evolution and phylogeography of the species, we aimed to facilitate such comparisons by extracting SNP signatures from past genotyping efforts and then incorporated these signatures into assays that quickly and easily define genotypes and phylogenetic groups. We found 91 polymorphisms (SNPs and indels among multispacer sequence typing (MST loci and designed 14 SNP-based assays that could be used to type samples based on previously established phylogenetic groups. These assays are rapid, inexpensive, real-time PCR assays whose results are unambiguous. Data from these assays allowed us to assign 43 previously untyped isolates to established genotypes and genomic groups. Furthermore, genotyping results based on assays from the signatures provided here are easily transferred between institutions, readily interpreted phylogenetically and simple to adapt to new genotyping technologies.

  10. Rapid purification of recombinant histones.

    Directory of Open Access Journals (Sweden)

    Henrike Klinker

    Full Text Available The development of methods to assemble nucleosomes from recombinant histones decades ago has transformed chromatin research. Nevertheless, nucleosome reconstitution remains time consuming to this day, not least because the four individual histones must be purified first. Here, we present a streamlined purification protocol of recombinant histones from bacteria. We termed this method "rapid histone purification" (RHP as it circumvents isolation of inclusion bodies and thereby cuts out the most time-consuming step of traditional purification protocols. Instead of inclusion body isolation, whole cell extracts are prepared under strongly denaturing conditions that directly solubilize inclusion bodies. By ion exchange chromatography, the histones are purified from the extracts. The protocol has been successfully applied to all four canonical Drosophila and human histones. RHP histones and histones that were purified from isolated inclusion bodies had similar purities. The different purification strategies also did not impact the quality of octamers reconstituted from these histones. We expect that the RHP protocol can be readily applied to the purification of canonical histones from other species as well as the numerous histone variants.

  11. 78 FR 11678 - Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI

    Science.gov (United States)

    2013-02-19

    ... National Park Service Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: The Grand Rapids Public Museum has completed an... Grand Rapids Public Museum. Repatriation of the human remains and associated funerary objects to...

  12. 77 FR 11575 - Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI

    Science.gov (United States)

    2012-02-27

    ... National Park Service Notice of Inventory Completion: Grand Rapids Public Museum, Grand Rapids, MI AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: The Grand Rapids Public Museum has completed an... Rapids Public Museum. Repatriation of the human remains and associated funerary objects to the...

  13. RAPID TRANSFER ALIGNMENT USING FEDERATED KALMAN FILTER

    Institute of Scientific and Technical Information of China (English)

    GUDong-qing; QINYong-yuan; PENGRong; LIXin

    2005-01-01

    The dimension number of the centralized Kalman filter (CKF) for the rapid transfer alignment (TA) is as high as 21 if the aircraft wing flexure motion is considered in the rapid TA. The 21-dimensional CKF brings the calculation burden on the computer and the difficulty to meet a high filtering updating rate desired by rapid TA. The federated Kalman filter (FKF) for the rapid TA is proposed to solve the dilemma. The structure and the algorithm of the FKF, which can perform parallel computation and has less calculation burden, are designed.The wing flexure motion is modeled, and then the 12-order velocity matching local filter and the 15-order attitud ematching local filter are devised. Simulation results show that the proposed EKE for the rapid TA almost has the same performance as the CKF. Thus the calculation burden of the proposed FKF for the rapid TA is markedly decreased.

  14. Rapid nuclear import of short nucleic acids.

    Science.gov (United States)

    Kitagawa, Mai; Okamoto, Akimitsu

    2016-10-01

    Exogenous short-chain nucleic acids undergo rapid import into the nucleus. Fluorescence-labeled dT1-13 DNA microinjected into the cytoplasm domain of a HeLa cell was rapidly imported into the nucleus domain within 1min. This is much more rapid than what has been observed for intracellular diffusion of small molecules. In contrast, import of longer nucleic acids with a length of over 30nt into the nucleus was suppressed. PMID:27597250

  15. Rapid Automated Mission Planning System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is an automated UAS mission planning system that will rapidly identify emergency (contingency) landing sites, manage contingency routing,...

  16. Rapidity Correlation Structures from Causal Hydrodynamics

    CERN Document Server

    Gavin, Sean; Zin, Christopher

    2016-01-01

    Viscous diffusion can broaden the rapidity dependence of two-particle transverse momentum fluctuations. Surprisingly, measurements at RHIC by the STAR collaboration demonstrate that this broadening is accompanied by the appearance of unanticipated structure in the rapidity distribution of these fluctuations in the most central collisions. Although a first order classical Navier-Stokes theory can roughly explain the rapidity broadening, it cannot explain the additional structure. We propose that the rapidity structure can be explained using the second order causal Israel-Stewart hydrodynamics with stochastic noise.

  17. Rapid methods for detection of bacteria

    DEFF Research Database (Denmark)

    Corfitzen, Charlotte B.; Andersen, B.Ø.; Miller, M.;

    2006-01-01

    Traditional methods for detection of bacteria in drinking water e.g. Heterotrophic Plate Counts (HPC) or Most Probable Number (MNP) take 48-72 hours to give the result. New rapid methods for detection of bacteria are needed to protect the consumers against contaminations. Two rapid methods...

  18. Rapid eye movement sleep behavior disorder

    DEFF Research Database (Denmark)

    Schenck, C H; Montplaisir, J Y; Frauscher, B;

    2013-01-01

    We aimed to provide a consensus statement by the International Rapid Eye Movement Sleep Behavior Disorder Study Group (IRBD-SG) on devising controlled active treatment studies in rapid eye movement sleep behavior disorder (RBD) and devising studies of neuroprotection against Parkinson disease (PD...

  19. Set point calculations for RAPID project

    International Nuclear Information System (INIS)

    The Respond and Pump in Days (RAPID) project was initiated to pump part of the contents of tank 241-SY-101 into tank 241-SY-102. This document establishes the basis for all set points and ranges used in the RAPID project

  20. Set point calculations for RAPID project

    Energy Technology Data Exchange (ETDEWEB)

    HICKMAN, G.L.

    1999-10-18

    The Respond and Pump in Days (RAPID) project was initiated to pump part of the contents of tank 241-SY-101 into tank 241-SY-102. This document establishes the basis for all set points and ranges used in the RAPID project.

  1. A new method for rapid Canine retraction

    Directory of Open Access Journals (Sweden)

    "Khavari A

    2001-06-01

    Full Text Available Distraction osteogenesis method (Do in bone lengthening and rapid midpalatal expansion have shown the great ability of osteognic tissues for rapid bone formation under distraction force and special protocol with optimum rate of one millimeter per day. Periodontal membrane of teeth (PDM is the extension of periostium in the alveolar socked. Orthodontic force distracts PDM fibers in the tension side and then bone formation will begin.Objects: Rapid retraction of canine tooth into extraction space of first premolar by DO protocol in order to show the ability of the PDM in rapid bone formation. The other objective was reducing total orthodontic treatment time of extraction cases.Patients and Methods: Tweleve maxillary canines in six patients were retracted rapidly in three weeks by a custom-made tooth-born appliance. Radiographic records were taken to evaluate the effects of heavy applied force on canine and anchorage teeth.Results: Average retraction was 7.05 mm in three weeks (2.35 mm/week. Canines rotated distal- in by mean 3.5 degrees.Anchorage loss was from 0 to 0.8 mm with average of 0.3 mm.Root resorption of canines was negligible, and was not significant clinically. Periodontium was normal after rapid retraction. No hazard for pulp vitality was observed.Discussion: PDM responded well to heavy distraction force by Do protocol. Rapid canine retraction seems to be a safe method and can considerabely reduce orthodontic time.

  2. Risks and benefits of rapid clozapine titration

    Directory of Open Access Journals (Sweden)

    Jeannie D. Lochhead

    2016-05-01

    Full Text Available Clozapine is often considered the gold standard for the treatment of schizophrenia. Clinical guidelines suggest a gradual titration over 2 weeks to reduce the risks of adverse events such as seizures, hypotension, agranulocytosis, and myocarditis. The slow titration often delays time to therapeutic response. This raises the question of whether, in some patients, it may be safe to use a more rapid clozapine titration. The following case illustrates the potential risks associated with the use of multiple antipsychotics and rapid clozapine titration. We present the case of a young man with schizophrenia who developed life threatening neuroleptic malignant syndrome (NMS during rapid clozapine titration and treatment with multiple antipsychotics. We were unable to find another case in the literature of NMS associated with rapid clozapine titration. This case is meant to urge clinicians to carefully evaluate the risks and benefits of rapid clozapine titration, and to encourage researchers to further evaluate the safety of rapid clozapine titration. Rapid clozapine titration has implications for decreasing health care costs associated with prolonged hospitalizations, and decreasing the emotional suffering associated with uncontrolled symptoms of psychosis. Clozapine is considered the most effective antipsychotic available thus efforts should focus on developing strategies that would allow for safest and most efficient use of clozapine to encourage its utilization for treatment resistance schizophrenia.

  3. Hadron rapidity spectra within a hybrid model

    CERN Document Server

    Khvorostukhin, A S

    2016-01-01

    A 2-stage hybrid model is proposed that joins the fast initial state of interaction, described by the hadron string dynamics (HSD) model, to subsequent evolution of the expanding system at the second stage, treated within ideal hydrodynamics. The developed hybrid model is assigned to describe heavy-ion collisions in the energy range of the NICA collider under construction in Dubna. Generally, the model is in reasonable agreement with the available data on proton rapidity spectra. However, reproducing proton rapidity spectra, our hybrid model cannot describe the rapidity distributions of pions. The model should be improved by taking into consideration viscosity effects at the hydrodynamical stage of system evolution.

  4. Zika Spreading Rapidly Through Puerto Rico: CDC

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_159430.html Zika Spreading Rapidly Through Puerto Rico: CDC Possibly hundreds ... 2016 FRIDAY, June 17, 2016 (HealthDay News) -- The Zika virus is spreading fast through Puerto Rico, placing ...

  5. Soft-/rapidity- anomalous dimensions correspondence

    CERN Document Server

    Vladimirov, Alexey A

    2016-01-01

    We establish a correspondence between ultraviolet singularities of soft factors for multi-particle production and rapidity singularities of soft factors for multi-parton scattering. This correspondence is a consequence of a conformal mapping between scattering geometries. The correspondence is valid to all orders of perturbation theory and in this way provides a proof of rapidity renormalization procedure for multi-parton scattering soft factors (including the transverse momentum dependent (TMD) soft factor as a special case). As a by-product we obtain an exact relation between the rapidity anomalous dimension and the well-known soft anomalous dimension. The three-loop rapidity anomalous dimensions for TMD and a general multi-parton scattering are derived.

  6. Ceramic microfabrication by rapid prototyping process chains

    Indian Academy of Sciences (India)

    R Knitter; W Bauer

    2003-02-01

    Fabrication of micropatterned ceramics or ceramic microparts make high demands on the precision and resolution of the moulding process. As finishing of miniaturised or micropatterned ceramic components is nearly impossible, shaping has to be done by a replication step in the green, unfired state. To avoid high tooling costs in product development, a rapid prototyping process chain has been established that enables rapid manufacturing of ceramic microcomponents from functional models to small lot series within a short time. This process chain combines the fast and inexpensive supply of master models by rapid prototyping with accurate and flexible ceramic manufacturing by low-pressure injection moulding. Besides proper feedstock preparation and sufficient small grain size, the quality of the final components is mainly influenced by the quality of the master model. Hence, the rapid prototyping method must be carefully selected to meet the requirements of the component to be fabricated.

  7. Rapid Update Cycle (RUC) [13 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Update Cycle (RUC) weather forecast model was developed by the National Centers for Environmental Prediction (NCEP). On May 1, 2012, the RUC was replaced...

  8. Development of a Rapid Thermoplastic Impregnation Device

    NARCIS (Netherlands)

    Weustink, A.P.D.

    2007-01-01

    A melt impregnation device for rapid thermoplastic impregnation of fiber bundles has been developed through modeling and experiments. The basic principles behind the thermoplastic impregnation process are investigated and the properties needed for a successful thermoplastic impregnation device are f

  9. Colorado Plateau Rapid Ecoregion Assessment Data Catalog

    Data.gov (United States)

    Bureau of Land Management, Department of the Interior — Datasets used in the analysis of the Colorado Plateau (COP) Rapid Ecoregion Assessment (REA).They can be downloaded via a layer package (lpk, similar to a zip file...

  10. Rapid Development of the Radiation Curing Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Radiation curing is an advanced material surface treatment technology using ultraviolet (UV) radiation and electronic beams (EB). With the greater attention paid to environ mentel protection in recent years ,radiation curing has developed rapidly.

  11. Rapidity Correlation Structure in Nuclear Collisions

    CERN Document Server

    Gavin, Sean; Zin, Christopher

    2016-01-01

    We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time $\\tau_\\pi$ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity $\

  12. The Rapid Perceptual Impact of Emotional Distractors.

    Directory of Open Access Journals (Sweden)

    Briana L Kennedy

    Full Text Available The brief presentation of an emotional distractor can temporarily impair perception of a subsequent, rapidly presented target, an effect known as emotion-induced blindness (EIB. How rapidly does this impairment unfold? To probe this question, we examined EIB for targets that immediately succeeded ("lag-1" emotional distractors in a rapid stream of items relative to EIB for targets at later serial positions. Experiments 1 and 2 suggested that emotional distractors interfere with items presented very soon after them, with impaired target perception emerging as early as lag-1. Experiment 3 included an exploratory examination of individual differences, which suggested that EIB onsets more rapidly among participants scoring high in measures linked to negative affect.

  13. An Exponential Regulator for Rapidity Divergences

    CERN Document Server

    Li, Ye; Zhu, Hua Xing

    2016-01-01

    Finding an efficient and compelling regularization of soft and collinear degrees of freedom at the same invariant mass scale, but separated in rapidity is a persistent problem in high-energy factorization. In the course of a calculation, one encounters divergences unregulated by dimensional regularization, often called rapidity divergences. Once regulated, a general framework exists for their renormalization, the rapidity renormalization group (RRG), leading to fully resummed calculations of transverse momentum (to the jet axis) sensitive quantities. We examine how this regularization can be implemented via a multi-differential factorization of the soft-collinear phase-space, leading to an (in principle) alternative non-perturbative regularization of rapidity divergences. As an example, we examine the fully-differential factorization of a color singlet's momentum spectrum in a hadron-hadron collision at threshold. We show how this factorization acts as a mother theory to both traditional threshold and transve...

  14. Rapid Update Cycle (RUC) [20 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Update Cycle (RUC) weather forecast model was developed by the National Centers for Environmental Prediction (NCEP). On May 1, 2012, the RUC was replaced...

  15. A rapid method of ferromanganese nodule mounting

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, S.; Banerjee, R.

    GEOLOGICAL SOCIETY OF INDIA Vol. 36. Aug. 1990. pp. 173 to 174 A Rapid Method of Ferromanganese Nodule Mounting S. MUKHOPADHYAYl AND R. BANERJEE2 1 Department of Geological Sciences, Jadavpur University, Calcutta 700032 2 National Institute of Oceanography.... Dona Paula, Goa 403 004 Abstract. A rapid method of sample preparation for ferromanganese nodules andcrusts mounting is presented here. by using laminated polyester resin. cobalt napthanate and methyl ethyl ketone peroxide. With- this technique vacuum...

  16. Rapid coal proximate analysis by thermogravimetric method

    Energy Technology Data Exchange (ETDEWEB)

    Mao Jianxiong; Yang Dezhong; Zhao Baozhong

    1987-09-01

    A rapid coal proximate analysis by thermogravimetric analysis (TGA) can be used as an alternative method for the standard proximate analysis. This paper presents a program set up to rapidly perform coal proximate analysis by using a thermal analyzer and TGA module. A comparison between coal proximate analyses by standard method (GB) and TGA is also given. It shows that most data from TGA fall within the tolerance limit of standard method.

  17. Rapid HIV Testing in Large Urban Jails

    OpenAIRE

    Beckwith, Curt G.; Nunn, Amy; Baucom, Sharon; Getachew, Asresahegn; Akinwumi, Akin; Herdman, Bruce; DiBartolo, Phil; Spencer, Susan; Brown, Devon; Lesansky, Henry; Kuo, Irene

    2012-01-01

    HIV prevalence is higher in jails than in the community, yet many jails do not conduct HIV testing. Jails in Baltimore, Maryland; Philadelphia, Pennsylvania; and the District of Columbia have implemented innovative rapid HIV testing programs. We have summarized the results of these programs, including the numbers of persons tested, rapid and confirmatory HIV test results, and numbers of persons newly diagnosed with HIV. We have described facilitators and challenges of implementation. These pr...

  18. Exploring data with RapidMiner

    CERN Document Server

    Chisholm, Andrew

    2013-01-01

    A step-by-step tutorial style using examples so that users of different levels will benefit from the facilities offered by RapidMiner.If you are a computer scientist or an engineer who has real data from which you want to extract value, this book is ideal for you. You will need to have at least a basic awareness of data mining techniques and some exposure to RapidMiner.

  19. Review on CNC-Rapid Prototyping

    Science.gov (United States)

    Z, M. Nafis O.; Y, Nafrizuan M.; A, Munira M.; J, Kartina

    2012-09-01

    This article reviewed developments of Computerized Numerical Control (CNC) technology in rapid prototyping process. Rapid prototyping (RP) can be classified into three major groups; subtractive, additive and virtual. CNC rapid prototyping is grouped under the subtractive category which involves material removal from the workpiece that is larger than the final part. Richard Wysk established the use of CNC machines for rapid prototyping using sets of 2½-D tool paths from various orientations about a rotary axis to machine parts without refixturing. Since then, there are few developments on this process mainly aimed to optimized the operation and increase the process capabilities to stand equal with common additive type of RP. These developments include the integration between machining and deposition process (hybrid RP), adoption of RP to the conventional machine and optimization of the CNC rapid prototyping process based on controlled parameters. The article ended by concluding that the CNC rapid prototyping research area has a vast space for improvement as in the conventional machining processes. Further developments and findings will enhance the usage of this method and minimize the limitation of current approach in building a prototype.

  20. Review on CNC-Rapid Prototyping

    International Nuclear Information System (INIS)

    This article reviewed developments of Computerized Numerical Control (CNC) technology in rapid prototyping process. Rapid prototyping (RP) can be classified into three major groups; subtractive, additive and virtual. CNC rapid prototyping is grouped under the subtractive category which involves material removal from the workpiece that is larger than the final part. Richard Wysk established the use of CNC machines for rapid prototyping using sets of 2½-D tool paths from various orientations about a rotary axis to machine parts without refixturing. Since then, there are few developments on this process mainly aimed to optimized the operation and increase the process capabilities to stand equal with common additive type of RP. These developments include the integration between machining and deposition process (hybrid RP), adoption of RP to the conventional machine and optimization of the CNC rapid prototyping process based on controlled parameters. The article ended by concluding that the CNC rapid prototyping research area has a vast space for improvement as in the conventional machining processes. Further developments and findings will enhance the usage of this method and minimize the limitation of current approach in building a prototype.

  1. Modified TB rapid test by proteinase K for rapid diagnosis of pleural tuberculosis.

    Science.gov (United States)

    Yari, Shamsi; Hadizadeh Tasbiti, Alireza; Ghanei, Mostafa; Shokrgozar, Mohammad Ali; Fateh, Abolfazl; Yari, Fatemeh; Bahrmand, Ahmadreza

    2016-03-01

    The diagnosis of pleural tuberculosis continues to be a challenge due to the low sensitivity of traditional diagnostic methods. Better and more rapid tests are needed for diagnosis of pleural TB. In this study, pleural fluids were tested with rapid test to determine Mycobacterium tuberculosis (MTB antigen). Affinity chromatography was used to purify specific polyclonal antibodies against MTB antigen. Pleural samples after decontamination were treated with proteinase K. Rapid test for pleural fluids was prepared by specific antibody. Rapid test was performed on 85 pleural fluid patients. The patients had a mean age of 46.55 ± 15.96 years and 38 were men. The performance of rapid test, using proteinase K, was found to be the most impressive: sensitivity 93%, specificity 94%, PPV 90%, and NPV 96% compared with adenosine deaminase test (ADA), PCR, smear, and culture. The present study did demonstrate that modified TB rapid test can substantially improve the diagnosis of extrapulmonary TB.

  2. Prostate treatments, 1MRT o RapidArc; Tratamiento de prostata, IMART o RapidArc?

    Energy Technology Data Exchange (ETDEWEB)

    Castro novais, J.; Ruiz Maqueda, S.; Pardo Perez, E.; Molina Lopez, M. Y.; Cerro Penalver, E.

    2015-07-01

    Techniques that modulate the dose (as IMRT or RapidArcTM) improve dose homogeneity within the target volume decreasing the dose in healthy organs. The aim of this work is to study the dosimetric differences in prostate radiotherapy treatments with IMRT and RapidArcTM. The results of the 109 patients studied show that plans to RapidArcTM have better coverage, compliance and dose gradient outside the target volume. (Author)

  3. Evaluation of rapid diagnostic test for influenza

    Directory of Open Access Journals (Sweden)

    Tiziano Allice

    2009-06-01

    Full Text Available In high risk patients such as in eldery, newborns and immunosuppressed subjects, a timely diagnosis of influenza is required for the most appropriate antiviral strategy in order to avoid severe secondary respiratory complications and viral spreading. Influenza is preventable by vaccination and chemoprophylaxis and is treatable by specific antiviral indications. The need for a timely diagnosis has led to the introduction of numerous rapid diagnostic tests.These are mostly antigen detection test giving results within 30 minutes, a clinically relevant time-frame to complement with the use of antiviral medications or chemoprophylaxis strategy. When evaluating performances of rapid test for influenza viruses, it is important to consider the type and quality of specimen to be tested, as well as sensitivity and specificity of the assays. Nasal/nasopharyngeal swabs are the most frequently submitted specimens, but nasal/nasopharingeal aspirates and washs can improve the diagnostic sensitivity of the test. Only some rapid assays can be successful used with broncoalveolar washings. In this review,we evaluated the sensitivity, specificity, reproducibility and feasibility of the most currently licensed rapid tests for influenza virus A and B. A flow-chart for the laboratory diagnosis of influenza with rapid test in combination with confirmatory test is proposed.

  4. Open architecture for rapid deployment of capability

    Science.gov (United States)

    Glassman, Jacob

    2016-05-01

    Modern warfare has drastically changed from conventional to non-conventional and from fixed threats to dynamic ones over the past several decades. This unprecedented fundamental shift has now made our adversaries and their weapons more nebulous and ever changing. Our current acquisition system however is not suited to develop, test and deploy essential capability to counter these dynamic threats in time to combat them. This environment requires a new infrastructure in our system design to rapidly adopt capabilities that we do not currently plan for or even know about. The key to enabling this rapid implementation is Open Architecture in acquisition. The DoD has shown it can rapidly prototype capabilities such as unmanned vehicles but has severely struggled in moving from the prototyping to deployment. A major driver of this disconnect is the lack of established infrastructure to employ said capability such as launch and recovery systems and command and control. If we are to be successful in transitioning our rapid capability to the warfighter we must implement established well defined interfaces and enabling technologies to facilitate the rapid adoption of capability so the warfighter has the tools to effectively counter the threat.

  5. Rapid, generalized adaptation to asynchronous audiovisual speech.

    Science.gov (United States)

    Van der Burg, Erik; Goodbourn, Patrick T

    2015-04-01

    The brain is adaptive. The speed of propagation through air, and of low-level sensory processing, differs markedly between auditory and visual stimuli; yet the brain can adapt to compensate for the resulting cross-modal delays. Studies investigating temporal recalibration to audiovisual speech have used prolonged adaptation procedures, suggesting that adaptation is sluggish. Here, we show that adaptation to asynchronous audiovisual speech occurs rapidly. Participants viewed a brief clip of an actor pronouncing a single syllable. The voice was either advanced or delayed relative to the corresponding lip movements, and participants were asked to make a synchrony judgement. Although we did not use an explicit adaptation procedure, we demonstrate rapid recalibration based on a single audiovisual event. We find that the point of subjective simultaneity on each trial is highly contingent upon the modality order of the preceding trial. We find compelling evidence that rapid recalibration generalizes across different stimuli, and different actors. Finally, we demonstrate that rapid recalibration occurs even when auditory and visual events clearly belong to different actors. These results suggest that rapid temporal recalibration to audiovisual speech is primarily mediated by basic temporal factors, rather than higher-order factors such as perceived simultaneity and source identity.

  6. Rapid steroid hormone actions via membrane receptors.

    Science.gov (United States)

    Schwartz, Nofrat; Verma, Anjali; Bivens, Caroline B; Schwartz, Zvi; Boyan, Barbara D

    2016-09-01

    Steroid hormones regulate a wide variety of physiological and developmental functions. Traditional steroid hormone signaling acts through nuclear and cytosolic receptors, altering gene transcription and subsequently regulating cellular activity. This is particularly important in hormonally-responsive cancers, where therapies that target classical steroid hormone receptors have become clinical staples in the treatment and management of disease. Much progress has been made in the last decade in detecting novel receptors and elucidating their mechanisms, particularly their rapid signaling effects and subsequent impact on tumorigenesis. Many of these receptors are membrane-bound and lack DNA-binding sites, functionally separating them from their classical cytosolic receptor counterparts. Membrane-bound receptors have been implicated in a number of pathways that disrupt the cell cycle and impact tumorigenesis. Among these are pathways that involve phospholipase D, phospholipase C, and phosphoinositide-3 kinase. The crosstalk between these pathways has been shown to affect apoptosis and proliferation in cardiac cells, osteoblasts, and chondrocytes as well as cancer cells. This review focuses on rapid signaling by 17β-estradiol and 1α,25-dihydroxy vitamin D3 to examine the integrated actions of classical and rapid steroid signaling pathways both in contrast to each other and in concert with other rapid signaling pathways. This new approach lends insight into rapid signaling by steroid hormones and its potential for use in targeted drug therapies that maximize the benefits of traditional steroid hormone-directed therapies while mitigating their less desirable effects. PMID:27288742

  7. Rapid penetration into granular media visualizing the fundamental physics of rapid earth penetration

    CERN Document Server

    Iskander, Magued

    2015-01-01

    Rapid Penetration into Granular Media: Visualizing the Fundamental Physics of Rapid Earth Penetration introduces readers to the variety of methods and techniques used to visualize, observe, and model the rapid penetration of natural and man-made projectiles into earth materials. It provides seasoned practitioners with a standard reference that showcases the topic's most recent developments in research and application. The text compiles the findings of new research developments on the subject, outlines the fundamental physics of rapid penetration into granular media, and assembles a com

  8. Wreathes of Magnetism in Rapidly Rotating Suns

    CERN Document Server

    Brown, Benjamin P; Brun, Allan Sacha; Toomre, Juri

    2009-01-01

    When our Sun was young it rotated much more rapidly than now. Observations of young, rapidly rotating stars indicate that many possess substantial magnetic activity and strong axisymmetric magnetic fields. We conduct simulations of dynamo action in rapidly rotating suns with the 3-D MHD anelastic spherical harmonic (ASH) code to explore the complex coupling between rotation, convection and magnetism. Here we study dynamo action realized in the bulk of the convection zone for two systems, rotating at three and five times the current solar rate. We find that substantial organized global-scale magnetic fields are achieved by dynamo action in these systems. Striking wreathes of magnetism are built in the midst of the convection zone, coexisting with the turbulent convection. This is a great surprise, for many solar dynamo theories have suggested that a tachocline of penetration and shear at the base of the convection zone is a crucial ingredient for organized dynamo action, whereas these simulations do not includ...

  9. Rapid auditory learning of temporal gap detection.

    Science.gov (United States)

    Mishra, Srikanta K; Panda, Manasa R

    2016-07-01

    The rapid initial phase of training-induced improvement has been shown to reflect a genuine sensory change in perception. Several features of early and rapid learning, such as generalization and stability, remain to be characterized. The present study demonstrated that learning effects from brief training on a temporal gap detection task using spectrally similar narrowband noise markers defining the gap (within-channel task), transfer across ears, however, not across spectrally dissimilar markers (between-channel task). The learning effects associated with brief training on a gap detection task were found to be stable for at least a day. These initial findings have significant implications for characterizing early and rapid learning effects. PMID:27475211

  10. Rapid Hepatitis B Vaccination in Adults

    Directory of Open Access Journals (Sweden)

    Mansur Özcan

    2004-01-01

    Full Text Available Vaccination is a very important method in prevention of HBV.Especially rapid immunization takes an important place in subjects at highrisk. We have injected HBV vaccine to health workers who are attending inour hospital by rapid immunisation programme (at 0, 1 and 2 months andaimed to identify it’s efficiacy. Eighty seven subjects (69% male, 31%female were included to our study. Median age was 34 for male and 32 forwomen. We obtained 90% achievement of immunity rate after theprogramme finished. There were no significant difference between maleend female groups, and age groups. The non-responder rate was 11.6% inmale, and 7.4% in female. This rate was 6% in under 40 years old group,and 22.7% in 40 or older group. This difference was significant in twogroups statistically (p=0.02. The rapid immunization programme, weperformed has nearly the same success results as in standard programme.

  11. Rapid Quench in an Electrostatic Levitator

    Science.gov (United States)

    SanSoucie, Michael P.; Rogers, Jan R.; Matson, Douglas M.

    2016-01-01

    The Electrostatic Levitation (ESL) Laboratory at the NASA Marshall Space Flight Center (MSFC) is a unique facility for investigators studying high-temperature materials. The ESL laboratory's main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy, as a quench medium. Thereby allowing rapid quenching of undercooled liquid metals. Up to eight quench vessels can be loaded into a wheel inside the chamber that is indexed with control software. The system has been tested successfully with samples of zirconium, iron-cobalt alloys, titanium-zirconium-nickel alloys, and a silicon-cobalt alloy. This new rapid quench system will allow materials science studies of undercooled materials and new materials development. In this presentation, the system is described and some initial results are presented.

  12. Rapid Annealing Of Amorphous Hydrogenated Carbon

    Science.gov (United States)

    Alterovitz, Samuel A.; Pouch, John J.; Warner, Joseph D.

    1989-01-01

    Report describes experiments to determine effects of rapid annealing on films of amorphous hydrogenated carbon. Study represents first efforts to provide information for applications of a-C:H films where rapid thermal processing required. Major finding, annealing causes abrupt increase in absorption and concomitant decrease in optical band gap. Most of change occurs during first 20 s, continues during longer annealing times. Extend of change increases with annealing temperature. Researchers hypothesize abrupt initial change caused by loss of hydrogen, while gradual subsequent change due to polymerization of remaining carbon into crystallites or sheets of graphite. Optical band gaps of unannealed specimens on silicon substrates lower than those of specimens on quartz substrates.

  13. Cast Process Simulation for the Rapid Tooling.

    Science.gov (United States)

    Zhang, Renji; Jiang, Rui; Liu, Yuan; Yan, Yongnian

    1997-03-01

    A major use for RP (Rapid Prototyping) now is in the foundry industry. It is so called RT (Rapid Tooling). Models are used as patterns for sand and plaster casting or used as sacrificial models in investment casting in the RT. In order to improve casting quality, a cast process simulation program for the RT has been made. This simulation depends on analysis of size accuracy parameters. The result could be came back into the CAD forming program. After that a new CAD data have been adopted in RT process. Then the RT technology could have sufficient accuracy in fabrication. Work supported by the Natural Science Foundation of China (NSFC).

  14. Rapid serial visual presentation design for cognition

    CERN Document Server

    Spence, Robert

    2013-01-01

    A powerful new image presentation technique has evolved over the last twenty years, and its value demonstrated through its support of many and varied common tasks. Conceptually, Rapid Serial Visual Presentation (RSVP) is basically simple, exemplified in the physical world by the rapid riffling of the pages of a book in order to locate a known image. Advances in computation and graphics processing allow RSVP to be applied flexibly and effectively to a huge variety of common tasks such as window shopping, video fast-forward and rewind, TV channel selection and product browsing. At its heart is a

  15. The Boussinesq approximation in rapidly rotating flows

    CERN Document Server

    Lopez, Jose M; Avila, Marc

    2013-01-01

    In the classical formulation of the Boussinesq approximation centrifugal buoyancy effects related to differential rotation, as well as strong vortices in the flow, are neglected. However, these may play an important role in rapidly rotating flows, such as in astrophysical and geophysical applications, and also in turbulent convection. We here provide a straightforward approach resulting in a Boussinesq-type approximation that consistently accounts for centrifugal effects. We further compare our new approach to the classical one in fluid flows confined between two differentially heated and rotating cylinders. The results justify the need of using the proposed approximation in rapidly rotating flows.

  16. Light curves from rapidly rotating neutron stars

    OpenAIRE

    Numata, Kazutoshi; Lee, Umin

    2010-01-01

    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitu...

  17. Rapid web development using AJAX and Python

    International Nuclear Information System (INIS)

    We discuss the rapid development of a large scale data discovery service for the CMS experiment using modern AJAX techniques and the Python language. To implement a flexible interface capable of accommodating several different versions of the DBS database, we used a 'stack' approach. Asynchronous JavaScript and XML (AJAX) together with an SQL abstraction layer, template engine, code generation tool and dynamic queries provide powerful tools for constructing interactive interfaces to large amounts of data. We show how the use of these tools, with rapid development in a modern scripting language, improved the scalability and usability of the the search interface for different user communities

  18. Rapid radiochemical separations in neutron activation analysis

    International Nuclear Information System (INIS)

    Rapid radiochemical separation procedures based on the removal of metal ions by columns of C18-bonded silica gel after selective complexation are examined and the simplicity of the method demonstrated by its application to the determination of Mn, Cu and Zn in neutron-activated biological material. The method is rapid and reliable and readily adaptable in all radiochemical laboratories. An alternative separation procedure for selenium in blood plasma involving desalination and concentration of the selenium protein complex by gel filtration or ultrafiltration is briefly discussed. (author)

  19. Market design for rapid demand response

    DEFF Research Database (Denmark)

    Nielsen, Kurt; Tamirat, Tseganesh Wubale

    We suggest a market design for rapid demand response in electricity markets. The solution consists of remotely controlled switches, meters, forecasting models as well as a flexible auction market to set prices and select endusers job by job. The auction market motivates truth-telling and makes...

  20. A rapidly enlarging cutaneous hemangioma in pregnancy

    Directory of Open Access Journals (Sweden)

    Marwan Ma’ayeh

    2014-10-01

    Full Text Available This is a case of a rapidly enlarging cutaneous pedunculated tumor on a patient’s thumb during her pregnancy. This was excised and identified as a hemangioma. A literature search identified a possible hormonal factor in causing an accelerated growth of this tumor.

  1. The RapidEye mission design

    Science.gov (United States)

    Tyc, George; Tulip, John; Schulten, Daniel; Krischke, Manfred; Oxfort, Michael

    2005-01-01

    The RapidEye mission is a commercial remote sensing mission by the German Company RapidEye AG. The RapidEye mission will deliver information products for various customers in the agricultural insurance market, large producers, international institutions and cartography. The mission consists of a constellation of five identical small satellites and a sophisticated ground infrastructure based on proven systems. The five satellites will be placed in a single sun-synchronous orbit of approximately 620 km, with the satellites equally spaced over the orbit. The RapidEye system has the unique ability to image any area on earth once per day and can also provide large area coverage within 5 days. The satellites will each carry a 5 band multi-spectral optical imager with a ground sampling distance of 6.5 m at nadir and a swath width of 80 km. These capabilities along with the processing throughput of the ground segment allows the system to deliver the information products needed by the customers reliably and in a time frame that meets their specific needs.

  2. Rapid radiative clearing of protoplanetary discs

    CERN Document Server

    Haworth, Thomas J; Owen, James E

    2015-01-01

    The lack of observed transition discs with inner gas holes of radii greater than ~50AU implies that protoplanetary discs dispersed from the inside out must remove gas from the outer regions rapidly. We investigate the role of photoevaporation in the final clearing of gas from low mass discs with inner holes. In particular, we study the so-called "thermal sweeping" mechanism which results in rapid clearing of the disc. Thermal sweeping was originally thought to arise when the radial and vertical pressure scale lengths at the X-ray heated inner edge of the disc match. We demonstrate that this criterion is not fundamental. Rather, thermal sweeping occurs when the pressure maximum at the inner edge of the dust heated disc falls below the maximum possible pressure of X-ray heated gas (which depends on the local X-ray flux). We derive new critical peak volume and surface density estimates for rapid radiative clearing which, in general, result in rapid dispersal happening less readily than in previous estimates. Thi...

  3. A rapidly enlarging cutaneous hemangioma in pregnancy.

    LENUS (Irish Health Repository)

    Ma'ayeh, Marwan

    2014-06-18

    This is a case of a rapidly enlarging cutaneous pedunculated tumor on a patient\\'s thumb during her pregnancy. This was excised and identified as a hemangioma. A literature search identified a possible hormonal factor in causing an accelerated growth of this tumor.

  4. Rapidly pulsed, high intensity, incoherent light source

    Science.gov (United States)

    Evans, J. C., Jr.; Brandhorst, H. W., Jr. (Inventor)

    1974-01-01

    A rapid pulsing, high intensity, incoherent light is produced by selectively energizing a plurality of discharge lamps with a triggering circuit. Each lamp is connected to a capacitor, and a power supply is electrically connected to all but one of the capacitors. This last named capacitor is electrically connected to a discharge lamp which is connected to the triggering circuit.

  5. The Health Penalty of China's Rapid Urbanization

    NARCIS (Netherlands)

    E. Van de Poel (Ellen); O.A. O'Donnell (Owen); E.K.A. van Doorslaer (Eddy)

    2009-01-01

    textabstractRapid urbanization could have positive and negative health effects, such that the net impact on population health is not obvious. It is, however, highly pertinent to the human welfare consequences of development. This paper uses community and individual level longitudinal data from the C

  6. Rapid Development of Bioinformatics Education in China

    Science.gov (United States)

    Zhong, Yang; Zhang, Xiaoyan; Ma, Jian; Zhang, Liang

    2003-01-01

    As the Human Genome Project experiences remarkable success and a flood of biological data is produced, bioinformatics becomes a very "hot" cross-disciplinary field, yet experienced bioinformaticians are urgently needed worldwide. This paper summarises the rapid development of bioinformatics education in China, especially related undergraduate…

  7. The evolution of Rapid Burster outbursts

    NARCIS (Netherlands)

    Guerriero, R; Fox, DW; Kommers, J; Lewin, WHG; Rutledge, R; Moore, CB; Morgan, E; Van Paradijs, J; Van der Klis, M; Bildsten, L; Dotani, T

    1999-01-01

    We describe the evolutionary progression of an outburst of the Rapid Burster. Four outbursts have been observed with the Rossi X-Ray Timing Explorer between 1996 February and 1998 May, and our observations are consistent with a standard evolution over the course of each. An outburst can be divided i

  8. Implementing RapidArc into clinical routine

    DEFF Research Database (Denmark)

    Van Esch, Ann; Huyskens, Dominique P; Behrens, Claus F;

    2011-01-01

    With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto) I...

  9. Rapid eye movement sleep behavior disorder

    DEFF Research Database (Denmark)

    Zoetmulder, Marielle; Jennum, Poul

    2009-01-01

    Rapid eye movement (REM) sleep behaviour disorder (RBD) is characterized by loss of REM sleep and related electromyographic atonia with marked muscular activity and dream enactment behaviour. RBD is seen in 0.5% of the population. It occurs in an idiopathic form and secondarily to medical...

  10. JPSS CGS Tools For Rapid Algorithm Updates

    Science.gov (United States)

    Smith, D. C.; Grant, K. D.

    2011-12-01

    The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, JPSS replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the ground processing component of both POES and the Defense Meteorological Satellite Program (DMSP) replacement known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and the Interface Data Processing Segment (IDPS). Both are developed by Raytheon Intelligence and Information Systems (IIS). The Interface Data Processing Segment will process NPOESS Preparatory Project, Joint Polar Satellite System and Defense Weather Satellite System satellite data to provide environmental data products to NOAA and DoD processing centers operated by the United States government. Under NPOESS, Northrop Grumman Aerospace Systems Algorithms and Data Products (A&DP) organization was responsible for the algorithms that produce the EDRs, including their quality aspects. For JPSS, that responsibility has transferred to NOAA's Center for Satellite Applications & Research (STAR). As the Calibration and Validation (Cal/Val) activities move forward following both the NPP launch and subsequent JPSS and DWSS launches, rapid algorithm updates may be required. Raytheon and

  11. To Internationalize Rapidly from Inception: Crowdsource

    Directory of Open Access Journals (Sweden)

    Nirosh Kannangara

    2012-10-01

    Full Text Available Technology entrepreneurs continuously search for tools to accelerate the internationalization of their startups. For the purpose of internationalizing rapidly from inception, we propose that technology startups use crowdsourcing to internalize the tacit knowledge embodied in members of a crowd distributed across various geographies. For example, a technology startup can outsource to a large crowd the definition of a customer problem that occurs across various geographies, the development of the best solution to the problem, and the identification of attractive business expansion opportunities. In this article, we analyze how three small firms use crowdsourcing, discuss the benefits of crowdsourcing, and offer six recommendations to technology entrepreneurs interested in using crowdsourcing to rapidly internationalize their startups from inception.

  12. Rapid Treatment of Rhinophyma with Powered Microdebrider

    Directory of Open Access Journals (Sweden)

    C. Faris

    2013-01-01

    Full Text Available We describe here our experience in using sinus microdebrider to rapidly debulk and sculpt the tissues in cases of rhinophyma correction. We utilized the use of the 4 mm M4 Rotatable Cutting Straight Sinus Blade on a straight Straightshot M4 Microdebrider by Medtronic at 800 rpm oscillation which is normally utilised in our sinus surgery practice. The microdebrider is straightforward to use and is already stocked in most ENT departments. It requires no additional training or cost outlay for departments that perform endoscopic sinus surgery with microdebrider. In our experience it affords the surgeon the ability to rapidly and accurately sculpt the nose to an excellent aesthetic result. We feel it is a more precise tool than cold steel or Bovie cautery, quicker than CO2 laser techniques, and avoids the aerosol of dermabrasion. No complications occurred in our series, and all patients rated their cosmetic outcome as good to excellent.

  13. Rapid eutectic growth during free fall

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Rapid eutectic growth of Sb-24%Cu alloy is realized in the drop tube during the free fall under the containerless condition. Based on the analysis of crystal nucleation and eutectic growth in the free fall condition, it is indicated that, with the increase of undercooling, microstructural transition of Sb-24%Cu eutectic alloy proceeds from lamellar to anomalous eutectic structure. Undercoolings of 0-154 K have been obtained in experiment. The maximum undercooling exceeds to 0.19TE. Calculated results exhibit that Cu2Sb compound is the primary nucleation phase, and that the primary Sb dendrite will grow more rapidly than the eutectic structure when undercooling is larger than 40 K. The eutectic coupled zone around Sb-24%Cu eutectic alloy leads strongly to the Cu-rich side and covers a composition range from 23.0% to 32.7%Sb.

  14. Surgically assisted rapid maxillary expansion in adults.

    Science.gov (United States)

    Pogrel, M A; Kaban, L B; Vargervik, K; Baumrind, S

    1992-01-01

    Twelve adults with maxillary width discrepancy of greater than 5 mm were treated by surgically assisted rapid maxillary expansion. The procedure consisted of bilateral zygomatic buttress and midpalatal osteotomies combined with the use of a tooth-borne orthopedic device postoperatively. Mean palatal expansion of 7.5 mm (range of 6 to 13 mm), measured in the first molar region, was achieved within 3 weeks in all patients. Expansion remained stable during the 12-month study period, with a mean relapse for the entire group of 0.88 +/- 0.48 mm. Morbidity was limited to mild postoperative discomfort. The results of this preliminary study indicated that surgically assisted rapid maxillary expansion is a safe, simple, and reliable procedure for achieving a permanent increase in skeletal maxillary width in adults. Further study is necessary to document the three-dimensional movements of the maxillary segments and long-term stability of the skeletal and dental changes.

  15. Rapid parapatric speciation on holey adaptive landscapes

    CERN Document Server

    Gavrilets, S; Vose, M D; Gavrilets, Sergey; Li, Hai; Vose, Michael D.

    1998-01-01

    A classical view of speciation is that reproductive isolation arises as a by-product of genetic divergence. Here, individual-based simulations are used to evaluate whether the mechanisms implied by this view may result in rapid speciation if the only source of genetic divergence are mutation and random genetic drift. Distinctive features of the simulations are the consideration of the complete process of speciation (from initiation until completion), and of a large number of loci, which was only one order of magnitude smaller than that of bacteria. It is demonstrated that rapid speciation on the time scale of hundreds of generations is plausible without the need for extreme founder events, complete geographic isolation, the existence of distinct adaptive peaks or selection for local adaptation. The plausibility of speciation is enhanced by population subdivision. Simultaneous emergence of more than two new species from a subdivided population is highly probable. Numerical examples relevant to the theory of ce...

  16. Rapid eye movement sleep in breath holders.

    Science.gov (United States)

    Kohyama, J; Hasegawa, T; Shimohira, M; Fukumizu, M; Iwakawa, Y

    2000-07-01

    One-night polysomnography was performed on seven subjects suffering from breath-holding spells, including one whose death was suggested to be a consequence of a breath-holding spell. The fatal case showed no rapid eye movements (REMs) during REM sleep, although he exhibited REMs during wakefulness. The average numbers of both REMs and bursts of REMs in REM sleep in the other six breath holders were significantly lower than those in age-matched controls. The breath holders showed no airway obstruction, desaturation, or sleep fragmentation. Since the rapid ocular activity in REM sleep is generated in the brain stem, we hypothesized that a functional brainstem disturbance is involved in the occurrence of breath-holding spells.

  17. IFSAR for the Rapid Terrain Visualization Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    BURNS,BRYAN L.; EICHEL,PAUL H.; HENSLEY JR.,WILLIAM H.; KIM,THEODORE J.

    2000-10-31

    The Rapid Terrain Visualization Advanced Concept Technology Demonstration (RTV-ACTD) is designed to demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies. The primary sensor for this mission is an interferometric synthetic aperture radar (IFSAR) designed at Sandia National Laboratories. This paper will outline the design of the system and its performance, and show some recent flight test results. The RTV IFSAR will meet DTED level III and IV specifications by using a multiple-baseline design and high-accuracy differential and carrier-phase GPS navigation. It includes innovative near-real-time DEM production on-board the aircraft. The system is being flown on a deHavilland DHC-7 Army aircraft.

  18. Regional adaptive delaminating algorithm for rapid prototyping

    Institute of Scientific and Technical Information of China (English)

    CAI Daosheng; SHI Yusheng; HUANG Shuhuai

    2005-01-01

    With the development of rapid prototyping (RP) technology, the contradiction between fabricating speed and precision becomes more and more acute. In order to solve the contradiction, a regional effective adaptive delaminating algorithm is proposed in this paper. It is different from the traditional method that the regional adaptive delaminating method divides slicing contours into several regions and adaptively delaminates in respective region only according to the contours information. Namely, this method can not only adaptively delaminate at different height of CAD model but also adaptively delaminate different regions in one slicing layer. Furthermore, because the two-dimensional contour data adopted in this method are necessary for rapid prototyping system, this regional effective adaptive delaminating method is suitable for all RP systems. A comparative study is used to analyze the effectiveness of this method, which can demonstrate that this method can increase the fabricating speed and reduce the running cost under the condition of ensuring fabricating precision.

  19. Low Gravity Rapid Thermal Analysis of Glass

    Science.gov (United States)

    Tucker, Dennis S.; Ethridge, Edwin C.; Smith, Guy A.

    2004-01-01

    It has been observed by two research groups that ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass crystallization is suppressed in microgravity. The mechanism for this phenomenon is unknown at the present time. In order to better understand the mechanism, an experiment was performed on NASA's KC135 reduced gravity aircraft to obtain quantitative crystallization data. An apparatus was designed and constructed for performing rapid thermal analysis of milligram quantities of ZBLAN glass. The apparatus employs an ellipsoidal furnace allowing for rapid heating and cooling. Using this apparatus nucleation and crystallization kinetic data was obtained leading to the construction of time-temperature-transformation curves for ZBLAN in microgravity and unit gravity.

  20. Remarks on Rapid vs. Slow Star Formation

    CERN Document Server

    Ballesteros-Paredes, J; Ballesteros-Paredes, Javier; Hartmann, Lee

    2006-01-01

    Observational results and theoretical developments over the last few years have suggested that molecular cloud and star formation is relatively rapid and not strongly slowed by magnetic forces. It has recently been suggested that arguments for rapid star formation are flawed because they consider only the ages of pre-main sequence stars, and thus ignore the evolutionary lifetimes of starless cores. However, the rarity of molecular clouds without young stars in the solar neighborhood indicates that the time lag between cloud and star formation must be short, inconsistent with the above claim. We discuss problems with some observational estimates indicating long protostellar core lifetimes and large stellar age spreads in molecular clouds. We also point out some additional observational constraints which suggest that protostellar cores do not have long lifetimes before collapsing. It has also been suggested that the widths of spiral arms in external galaxies indicates the lifetime of molecular clouds, due to th...

  1. Rapid-Cycling Bubble-Chamber, details

    CERN Multimedia

    1980-01-01

    Parts of the hydraulic expansion system of the Rapid-Cycling Bubble-Chamber (RCBC). RCBC was the largest of 3 rapid-cycling bubble-chambers (the others were LEBC and HOLEBC), used as target- and vertex-detectors within the European Hybrid Spectrometer (EHS) in the SPS North Area (EHN1). RCBC contained 250 l of liquid hydrogen and was located inside a 3 T superconducting magnet. It was designed for 30 expansions/s (100 times faster than BEBC), the system shown here allowed 50 expansions/s. RCBC operated from 1981 to 1983 for experiments NA21, NA22 and NA23 at a rate of 15 expansions/s, clocking up a total of over 4 million. In the rear, at left, is bearded Lucien Veillet; Augustin Didona is at the right. See also 8001009. The installation of the piston assembly in the RCBC chamber body is shown in the Annual Report 1980, p.65.

  2. Diffraction and rapidity gap measurements with ATLAS

    CERN Document Server

    Kus, V; The ATLAS collaboration

    2014-01-01

    Two diffraction related measurements of proton-proton collisions in the ATLAS experiment of the Large Hadron Collider at $\\surd s$ = 7 TeV centre-of-mass energy are reviewed. First of them is a fraction of diffractive contribution to the inelastic cross section. Second measurement is dedicated to the identification of Single Diffractive interactions with large pseudo-rapidity gaps using early 2010 data sample of integrated luminosity 7.1 $\\mu b^{-1}$. Differential cross sections of largest forward areas of the ATLAS detector starting at its most forward edges $\\eta = \\pm 4.9$ without any particle activity above different transverse momentum thresholds are measured. Results are compared to several distinctive Monte Carlo models resulting in constraint of Pomeron intercept value in triple Pomeron based approach. Furthermore, proton-proton interactions in small pseudo-rapidity gap region test qualitatively a description of different hadronisation models as well as statistical fluctuations during hadronisation pr...

  3. Evaluation of rapid diagnostic test for influenza

    OpenAIRE

    Tiziano Allice; Valeria Ghisetti

    2009-01-01

    In high risk patients such as in eldery, newborns and immunosuppressed subjects, a timely diagnosis of influenza is required for the most appropriate antiviral strategy in order to avoid severe secondary respiratory complications and viral spreading. Influenza is preventable by vaccination and chemoprophylaxis and is treatable by specific antiviral indications. The need for a timely diagnosis has led to the introduction of numerous rapid diagnostic tests.These are mostly antigen detection tes...

  4. Learning environments and rapidly evolving handheld technologies

    OpenAIRE

    Ochola, J. Evans; Stachowiak, James R.; Achrazoglou, John G.; David B. Bills

    2013-01-01

    More and more K–12 school teachers are using handheld devices in classrooms. The mobile nature of handheld technologies is often seen as an integral characteristic facilitating collaborative learning and flexible learning arrangements. Since both portable devices and ideas about the learning environment are rapidly evolving, teachers need to be aware of technologies and classroom arrangements that can help improve student performance and classroom experiences.

  5. Rapid Prototyping Technology of Tissue Engineering Scaffold

    Institute of Scientific and Technical Information of China (English)

    管金鹏

    2014-01-01

    In the modern medicine field, the transplant of organ and tissue is a big problem due to serious shortage of donor organ. Artificial organ and tissue is one of solutions. With the development of science, various tissue manufacture techniques emerged. Hereinto, due to its versatility both in materials and structure, rapid prototyping technology has become one of the important methods for tissue engineering scaffold fabrication in this field.

  6. Rapid solidification of candidate ferritic steels

    International Nuclear Information System (INIS)

    HT-9 and 9Cr-1Mo steels were rapidly solidified by the liquid dynamic compaction process and 2-1/4Cr-1Mo steel was prepared by the ultrasonic gas atomization process. The consolidation was performed in the ferritic temperature range in order to minimize segregation. These alloys will be tested at ORNL using 1/3 CVN test specimens and the results will be compared with those for conventially processed alloys

  7. Rapid Output Growth of Special Acrylic Esters

    Institute of Scientific and Technical Information of China (English)

    Wang Lianzhi

    2007-01-01

    @@ Acrylic esters are usually classified into general-purpose varieties and special varieties. The production and application of general-purpose varieties is already quite matured in the world and their output growth tends to be flat. Owing to the development of coatings, electronics, automobiles,textiles, printing and construction sectors, especially the application of radiation curing technology in various sectors, special acrylic esters have developed rapidly.

  8. Rapid Separation of Fission Product 141La

    Institute of Scientific and Technical Information of China (English)

    XIA; Wen; YE; Hong-sheng; LIN; Min; CHEN; Ke-sheng; XU; Li-jun; ZHANG; Wei-dong; CHEN; Yi-zhen

    2013-01-01

    141La was separated and purified from fission products in this work for physical measurements aimed at improving the accuracy of its decay parameters.As the impact of 142La and other fission products,cesium(141Cs,142Cs included)was rapid separated from the fission products,141Cs and 142Ba separation was prepared after a cooling time about 25 s when 142Cs decays to daughter 142Ba,141La purification then

  9. Rapidity gaps between jets at D0

    International Nuclear Information System (INIS)

    Results are presented from an analysis of the particle multiplicity distribution between high transverse energy jets produced at the Fermilab Tevatron p bar p Collider at √s = 1.8 Tev. Using the D0 detector, we examine the particle multiplicity distribution between the two highest transverse energy jets. For events with large rapidity separation, we observed a significant excess of events at low tagged-particle multiplicity which is consistent with a strongly interacting color-singlet exchange process

  10. Rapid habituation of the cold shock response

    OpenAIRE

    Eglin, Clare M.; Butt, George; Howden, Stephen; Nash, Thomas; Costello, Joseph

    2015-01-01

    Sudden immersion into cold water initiates a series of cardio-respiratory responses collectively known as the cold shock response (CSR) which may increase an individual's risk of drowning. The CSR is stimulated by a rapid fall in skin temperature and includes tachycardia, a reflex inspiratory gasp followed by uncontrollable hyperventilation. Repeated cold water immersions conducted over several days have been shown to reduce the magnitude of the CSR [1]. This study investigated whether an hab...

  11. RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hiroshi [Department of Physics, Nagoya University, Nagoya, Aichi 464-8602 (Japan); Ormel, Chris W. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Ida, Shigeru, E-mail: hkobayas@nagoya-u.jp, E-mail: ormel@astro.berkeley.edu, E-mail: ida@geo.titech.ac.jp [Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)

    2012-09-01

    We have investigated Saturn's core formation at a radial pressure maximum in a protoplanetary disk, which is created by gap opening by Jupiter. A core formed via planetesimal accretion induces the fragmentation of surrounding planetesimals, which generally inhibits further growth of the core by removal of the resulting fragments due to radial drift caused by gas drag. However, the emergence of the pressure maximum halts the drift of the fragments, while their orbital eccentricities and inclinations are efficiently damped by gas drag. As a result, the core of Saturn rapidly grows via accretion of the fragments near the pressure maximum. We have found that in the minimum-mass solar nebula, kilometer-sized planetesimals can produce a core exceeding 10 Earth masses within two million years. Since Jupiter may not have undergone significant type II inward migration, it is likely that Jupiter's formation was completed when the local disk mass has already decayed to a value comparable to or less than Jovian mass. The expected rapid growth of Saturn's core on a timescale comparable to or shorter than the observationally inferred disk lifetime enables Saturn to acquire the current amount of envelope gas before the disk gas is completely depleted. The high heat energy release rate onto the core surface due to the rapid accretion of the fragments delays onset of runaway gas accretion until the core mass becomes somewhat larger than that of Jupiter, which is consistent with the estimate based on interior modeling. Therefore, the rapid formation of Saturn induced by gap opening of Jupiter can account for the formation of multiple gas giants (Jupiter and Saturn) without significant inward migration and larger core mass of Saturn than that of Jupiter.

  12. Rapid prototyping and stereolithography in dentistry

    OpenAIRE

    Sanjna Nayar; Bhuminathan, S.; Wasim Manzoor Bhat

    2015-01-01

    The word rapid prototyping (RP) was first used in mechanical engineering field in the early 1980s to describe the act of producing a prototype, a unique product, the first product, or a reference model. In the past, prototypes were handmade by sculpting or casting, and their fabrication demanded a long time. Any and every prototype should undergo evaluation, correction of defects, and approval before the beginning of its mass or large scale production. Prototypes may also be used for specific...

  13. RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION

    International Nuclear Information System (INIS)

    We have investigated Saturn's core formation at a radial pressure maximum in a protoplanetary disk, which is created by gap opening by Jupiter. A core formed via planetesimal accretion induces the fragmentation of surrounding planetesimals, which generally inhibits further growth of the core by removal of the resulting fragments due to radial drift caused by gas drag. However, the emergence of the pressure maximum halts the drift of the fragments, while their orbital eccentricities and inclinations are efficiently damped by gas drag. As a result, the core of Saturn rapidly grows via accretion of the fragments near the pressure maximum. We have found that in the minimum-mass solar nebula, kilometer-sized planetesimals can produce a core exceeding 10 Earth masses within two million years. Since Jupiter may not have undergone significant type II inward migration, it is likely that Jupiter's formation was completed when the local disk mass has already decayed to a value comparable to or less than Jovian mass. The expected rapid growth of Saturn's core on a timescale comparable to or shorter than the observationally inferred disk lifetime enables Saturn to acquire the current amount of envelope gas before the disk gas is completely depleted. The high heat energy release rate onto the core surface due to the rapid accretion of the fragments delays onset of runaway gas accretion until the core mass becomes somewhat larger than that of Jupiter, which is consistent with the estimate based on interior modeling. Therefore, the rapid formation of Saturn induced by gap opening of Jupiter can account for the formation of multiple gas giants (Jupiter and Saturn) without significant inward migration and larger core mass of Saturn than that of Jupiter.

  14. Rapid Growth of China Petroleum Machinery Manufacturing

    Institute of Scientific and Technical Information of China (English)

    Huang Zhiqian; Sun Zuchen

    1996-01-01

    @@ With the rapid development of China petroleum industry, its petroleum machinery manufacturing industry has expanded greatly and petroleum equipment level in the oilfields are continuously improved. Since the 1980s,China has successfully imported the advanced international petroleum manufacturing technology. So far 57 relevant contracts have been signed with foreign countries,involving technology, equipment, technology consultant,joint production and joint venture, which offer big helps to upgrade the petroleum machinery manufacturing technology.

  15. Rapid prototyping technologies in prosthetic dentistry

    OpenAIRE

    YILDIRIM, Arş. Gör. Dt. Melike Pınar; BAYINDIR, Prof. Dr. Funda

    2013-01-01

    Emerged as the concept of rapid prototyping technology, nowadays, is seen as the future of quick and direct production. This technology found applications with metal framework of fixed partial dentures, framework of removable partial dentures, facial protheses and titanium implants in prosthetic dentistry. The virtual image of the restoration is tranferred to the computer and the laser beam is sintered the selected areas on the alloy powders and the restoration is produced layer by layer at s...

  16. Rapid maxillary expansion in contemporary orthodontic literature

    OpenAIRE

    Sabrina Mutinelli; Mauro Cozzani

    2016-01-01

    We have reviewed our retrospective research about rapid maxillary expansion performed in the early mixed dentition to summarize the results of different studies regarding maxillary dental arch width variation and crowding improvement in light of contemporary literature. The aim is to define the effects of treatments followed until the end of dental arch growth. In all studies, a Haas expander anchored to the deciduous dentition was used. The samples consisted of treated patients with and with...

  17. RAPID WEBGIS DEVELOPMENT FOR EMERGENCY MANAGEMENT

    OpenAIRE

    Agosto, Eros; Dalmasso, Simone

    2011-01-01

    The use of spatial data during emergency response and management helps to make faster and better decisions. Moreover spatial data should be as much updated as possible and easy to access. To face the challenge of rapid and updated data sharing the most efficient solution is largely considered the use of internet where the field of web mapping is constantly evolving. ITHACA (Information Technology for Humanitarian Assistance, Cooperation and Action) is a non profit association founded by Polit...

  18. Development of a Rapid Coliphage Assat

    OpenAIRE

    Stanek, James Emmett

    1997-01-01

    A rapid coliphage detection assay (RCDA), based on the phage-induced release of b-galactosidase from cells of Escherichia coli (Ijzerman, M., J.O. Falkinham III and C. Hagedorn. (1993) [A liquid, colorimetric presence-absence coliphage detection method. J. Virol. Meth. 45:229-234] was modified to reduce the number of steps required to perform the assay, remove the need for specialized media and buffers, reduce the volumes required, and simplify growth and reaction conditions. Tolerances of t...

  19. Rapidity correlation structure in nuclear collisions

    Science.gov (United States)

    Gavin, Sean; Moschelli, George; Zin, Christopher

    2016-08-01

    We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time τπ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity ν =η /s T . We formulate methods for computing these correlations using second-order dissipative hydrodynamics with noise. Current data are consistent with τπ/ν ˜10 , but targeted measurements can improve this precision.

  20. CMOS-controlled rapidly tunable photodetectors

    Science.gov (United States)

    Chen, Ray

    With rapidly increasing data bandwidth demands, wavelength-division-multiplexing (WDM) optical access networks seem unavoidable in the near future. To operate WDM optical networks in an efficient scheme, wavelength reconfigurability and scalability of the network are crucial. Unfortunately, most of the existing wavelength tunable technologies are neither rapidly tunable nor spectrally programmable. This dissertation presents a tunable photodetector that is designed for dynamic-wavelength allocation WDM network environments. The wavelength tuning mechanism is completely different from existing technologies. The spectrum of this detector is programmable through low-voltage digital patterns. Since the wavelength selection is achieved by electronic means, the device wavelength reconfiguration time is as fast as the electronic switching time. In this dissertation work, we have demonstrated a tunable detector that is hybridly integrated with its customized CMOS driver and receiver with nanosecond wavelength reconfiguration time. In addition to its nanosecond wavelength reconfiguration time, the spectrum of this detector is digitally programmable, which means that it can adapt to system changes without re-fabrication. We have theoretically developed and experimentally demonstrated two device operating algorithms based on the same orthogonal device-optics basis. Both the rapid wavelength tuning time and the scalability make this novel device very viable for new reconfigurable WDM networks. By taking advantage of CMOS circuit design, this detector concept can be further extended for simultaneous multiple wavelength detection. We have developed one possible chip architecture and have designed a CMOS tunable optical demux for simultaneous controllable two-wavelength detection.

  1. Management of Infections with Rapidly Growing

    Directory of Open Access Journals (Sweden)

    Jong Hwan Kim

    2012-01-01

    Full Text Available Background Infection caused by rapidly growing mycobacteria (RGM is not uncommon, andthe prevalence of RGM infection has been increasing. Clinical diagnosis is difficult becausethere are no characteristic clinical features. There is also no standard antibiotic regimenfor treating RGM infection. A small series of patients with RGM infections was studied toexamine their treatments and outcomes.Methods A total of 5 patients who had developed postoperative infections from January2009 to December 2010 were retrospectively reviewed. Patients were initially screened using amycobacteria rapid screening test (polymerase chain reaction [PCR]-reverse blot hybridizationassay. To confirm mycobacterial infection, specimens were cultured for nontuberculousmycobacteria and analyzed by 16 S ribosomal RNA and rpoB gene PCR.Results The patients were treated with intravenous antibiotics during hospitalization,and oral antibiotics were administered after discharge. The mean duration of follow-upwas 9 months, and all patients were completely cured of infection with a regimen of acombination of antibiotics plus surgical treatment. Although none of the patients developedrecurrence, there were complications at the site of infection, including hypertrophic scarring,pigmentation, and disfigurement.Conclusions Combination antibiotic therapy plus drainage of surgical abscesses appeared tobe effective for the RGM infections seen in our patients. Although neither the exact dosagenor a standardized regimen has been firmly established, we propose that our treatment canprovide an option for the management of rapidly growing mycobacterial infection.

  2. Rapid determination of actinides in asphalt samples

    International Nuclear Information System (INIS)

    A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis. If a radiological dispersive device, improvised nuclear device or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean-up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organics present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well. (author)

  3. Rapid Progression of Coronary Atherosclerosis: A Review

    Directory of Open Access Journals (Sweden)

    Priyank Shah

    2015-01-01

    Full Text Available Atherosclerosis is chronic disease, the prevalence of which has increased steadily as the population ages. Vascular injury is believed to be critical initiating event in pathogenesis of spontaneous atherosclerosis. Syndrome of accelerated atherosclerosis has been classically described in patients undergoing heart transplantation, coronary artery bypass graft, and percutaneous transluminal coronary angioplasty. In contrast to spontaneous atherosclerosis, denuding endothelial injury followed by thrombus formation and initial predominant smooth muscle cell proliferation is believed to be playing a significant role in accelerated atherosclerosis. There is no universal definition of rapid progression of atherosclerosis. However most studies describing the phenomenon have used the following definition: (i > or = 10% diameter reduction of at least one preexisting stenosis > or = 50%, (ii > or = 30% diameter reduction of a preexisting stenosis <50%, and (iii progression of a lesion to total occlusion within few months. Recent studies have described the role of coronary vasospasm, human immunodeficiency virus, various inflammatory markers, and some genetic mutations as predictors of rapid progression of atherosclerosis. As research in the field of vascular biology continues, more factors are likely to be implicated in the pathogenesis of rapid progression of atherosclerosis.

  4. Rapid maxillary expansion in contemporary orthodontic literature

    Directory of Open Access Journals (Sweden)

    Sabrina Mutinelli

    2016-01-01

    Full Text Available We have reviewed our retrospective research about rapid maxillary expansion performed in the early mixed dentition to summarize the results of different studies regarding maxillary dental arch width variation and crowding improvement in light of contemporary literature. The aim is to define the effects of treatments followed until the end of dental arch growth. In all studies, a Haas expander anchored to the deciduous dentition was used. The samples consisted of treated patients with and without a lateral crossbite and homogeneous untreated individuals as controls. Two additional control groups of adolescents and adults in dental Class 1 were also compared. As a result of the analysis, rapid maxillary expansion with anchorage to the deciduous dentition was found to be effective in increasing transverse width in intermolar and intercanine areas, and the change was preserved until the full permanent dentition stage. When performed before maxillary lateral incisors have fully erupted, this procedure allows for a rapid increase in the arch length in the anterior area and consequently, in the space available for permanent incisors with a stable reduction in crowding over time.

  5. Robotic milling for rapid ceramic pototyping

    Institute of Scientific and Technical Information of China (English)

    HAN Guang-chao; ZHANG Hai-ou; WANG Gui-lan

    2005-01-01

    Robotic milling is a developing method for rapidly producing prototypes and parts, but the application is limited for materials such as wax, wood, plastic and light metal, etc. The reason for this is because of the robotic weak rigidity. In this paper, a method of robotic milling for ceramic prototyping is developed, one that has been successfully applied in a new rapid hard tooling technology-Direct Prototype Spray Tooling[1]. At first, the appropriate ceramic materials mixed with metal powder are confirmed for the robotic milling and the following plasma spraying process. Then the 6 - DOF robotic milling paths are extracted from the NC code and transformed into the robotic JBI type file, the NC code generated through the general CAD/CAM software such as UG -NX.Finally, the robotic milling characteristics such as moving path accuracy and milling force are tested to find the best milling parameters and to ensure the executable, accurate and efficient ceramic prototype milling technology.The development of this method not only broadens the robotic milling material range but also extends the rapid prototyping fields. It can also be used for producing ceramic parts that are difficult to machine.

  6. MSFC Electrostatic Levitator (ESL) Rapid Quench System

    Science.gov (United States)

    SanSoucie, Michael P.; Craven, Paul D.; Rogers, Jan R.

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) Laboratory is a unique facility for investigators studying high-temperature materials. The laboratory boasts two levitators in which samples can be levitated, heated, melted, undercooled, and resolidified, all without the interference of a container or data-gathering instrument. The ESL main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy. Thereby allowing rapid quenching of undercooled liquid metals. Up to 8 quench vessels can be loaded into the quench wheel, which is indexed with LabVIEW control software. This allows up to 8 samples to be rapidly quenched before having to open the chamber. The system has been tested successfully on several zirconium samples. Future work will be done with other materials using different quench mediums. Microstructural analysis will also be done on successfully quench samples.

  7. Rapid response manufacturing (RRM). Final CRADA report

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)

    1998-02-10

    US industry is fighting to maintain its competitive edge in the global market place. Markets fluctuate rapidly. Companies have to be able to respond quickly with improved, high quality, cost efficient products. Because companies and their suppliers are geographically distributed, rapid product realization is dependent on the development of a secure integrated concurrent engineering environment operating across multiple business entities. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies implemented in a secure environment. This documents the work done under this CRADA to develop capabilities, which permit the effective application, incorporation, and use of advanced technologies in a secure environment to facilitate the product realization process. Lockheed Martin Energy Systems (LMES), through a CRADA with the National Center for Manufacturing Sciences (NCMS), worked within a consortium of major industrial firms--Ford, General Motors, Texas Instruments, United Technologies, and Eastman Kodak--and several small suppliers of advanced manufacturing technology--MacNeal-Schwendler Corp., Teknowledge Corp., Cimplex Corp., Concentra, Spatial Technology, and Structural Dynamics Research Corp. (SDRC)--to create infrastructure to support the development and implementation of secure engineering environments for Rapid Response Manufacturing. The major accomplishment achieved under this CRADA was the demonstration of a prototypical implementation of a broad-based generic framework for automating and integrating the design-to-manufacturing activities associated with machined parts in a secure NWC compliant environment. Specifically, methods needed to permit the effective application, incorporation, and use of advanced technologies in a secure environment to facilitate the product realization process were developed and demonstrated. An important aspect of this demonstration was

  8. Rapid Reconnection and Field Line Topology

    Science.gov (United States)

    Parker, E. N.; Rappazzo, A. F.

    Rapid reconnection of magnetic fields arises where the magnetic stresses push the plasma and field so as to increase the field gradient without limit. The intent of the present writing is to show the larger topological context in which this commonly occurs. Consider an interlaced field line topology as commonly occurs in the bipolar magnetic regions on the Sun. A simple model is constructed starting with a strong uniform magnetic field B 0 in the z-direction through an infinitely conducting fluid from the end plate z = 0 to z = L with the field lines tied at both end plates. Field line interlacing is introduced by smooth continuous random turbulent mixing of the footpoints at the end plates. This configuration is well suited to be modeled with the reduced magnetohydrodynamic (MHD) equations, with the equilibria given by the solutions of the 2D vorticity equation in this case. The set of continuous solutions to the "vorticity" equation have greatly restricted topologies, so almost all interlaced field topologies do not have continuous solutions. That infinite set represents the "weak" solutions of the vorticity equation, wherein there are surfaces of tangential discontinuity (current sheets) in the field dividing regions of smooth continuous field. It follows then that current sheets are to be found throughout interlaced fields, providing potential sites for rapid reconnection. That is to say, rapid reconnection and nanoflaring are expected throughout the bipolar magnetic fields in the solar corona, providing substantial heating to the ambient gas. Numerical simulations provide a direct illustration of the process, showing that current sheets thin on fast ideal Alfvén timescales down to the smallest numerically resolved scales. The asymmetric structure of the equilibria and the interlacing threshold for the onset of singularities are discussed. Current sheet formation and dynamics are further analyzed with dissipative and ideal numerical simulations.

  9. Intraperitoneal Glucose Sensing is Sometimes Surprisingly Rapid

    Directory of Open Access Journals (Sweden)

    Anders Lyngvi Fougner

    2016-04-01

    Full Text Available Rapid, accurate and robust glucose measurements are needed to make a safe artificial pancreas for the treatment of diabetes mellitus type 1 and 2. The present gold standard of continuous glucose sensing, subcutaneous (SC glucose sensing, has been claimed to have slow response and poor robustness towards local tissue changes such as mechanical pressure, temperature changes, etc. The present study aimed at quantifying glucose dynamics from central circulation to intraperitoneal (IP sensor sites, as an alternative to the SC location. Intraarterial (IA and IP sensors were tested in three anaesthetized non-diabetic pigs during experiments with intravenous infusion of glucose boluses, enforcing rapid glucose level excursions in the range 70--360 mg/dL (approximately 3.8--20 mmol/L. Optical interferometric sensors were used for IA and IP measurements. A first-order dynamic model with time delay was fitted to the data after compensating for sensor dynamics. Additionally, off-the-shelf Medtronic Enlite sensors were used for illustration of SC glucose sensing. The time delay in glucose excursions from central circulation (IA to IP sensor location was found to be in the range 0--26 s (median: 8.5 s, mean: 9.7 s, SD 9.5 s, and the time constant was found to be 0.5--10.2 min (median: 4.8 min, mean: 4.7 min, SD 2.9 min. IP glucose sensing sites have a substantially faster and more distinctive response than SC sites when sensor dynamics is ignored, and the peritoneal fluid reacts even faster to changes in intravascular glucose levels than reported in previous animal studies. This study may provide a benchmark for future, rapid IP glucose sensors.

  10. A rapid diagnostic test for schistosomiasis mansoni

    Directory of Open Access Journals (Sweden)

    Clelia Christina Mello-Silva

    2013-12-01

    Full Text Available This article presents an improvement to the Kato-Katz (KK method, making it faster and more efficient for the visualisation of fertile eggs in stool samples. This modified KK method uses sodium acetate formalin as a fixative and reveals the intensity of infection in less than 1 h, reducing the diagnostic time without increasing the cost. This modified method may contribute to future epidemiological studies in both hospitals and the field due to its rapid and precise diagnostic, which allow for immediate treatment.

  11. Rapid River Hatchery - Spring Chinook, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Watson, M.

    1996-05-01

    This report presents the findings of the independent audit of the Rapid River Hatchery (Spring Chinook). The hatchery is located in the lower Snake River basin near Riggins Idaho. The hatchery is used for adult collection, egg incubation, and rearing of spring chinook. The audit was conducted in April 1996 as part of a two-year effort that will include 67 hatcheries and satellite facilities located on the Columbia and Snake River system in Idaho, Oregon, and Washington. The hatchery operating agencies include the US Fish and Wildlife Service, Idaho Department of Fish and Game, Oregon Department of Fish and Wildlife, and Washington Department of Fish and Wildlife.

  12. Chaotic Maps Dynamics, Fractals, and Rapid Fluctuations

    CERN Document Server

    Chen, Goong

    2011-01-01

    This book consists of lecture notes for a semester-long introductory graduate course on dynamical systems and chaos taught by the authors at Texas A&M University and Zhongshan University, China. There are ten chapters in the main body of the book, covering an elementary theory of chaotic maps in finite-dimensional spaces. The topics include one-dimensional dynamical systems (interval maps), bifurcations, general topological, symbolic dynamical systems, fractals and a class of infinite-dimensional dynamical systems which are induced by interval maps, plus rapid fluctuations of chaotic maps as a

  13. Rapid Response Manufacturing (RRM). Final CRADA report

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)

    1997-08-28

    A major accomplishment of the Rapid Response Manufacturing (RRM) project was the development of a broad-based generic framework for automating and integrating the design-to-manufacturing activities associated with machined part products. Key components of the framework are a manufacturing model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering working environment, knowledge-based software systems for design, process planning, and manufacturing and new production technologies for making products directly from design application software.

  14. Rapid technique for determining building material radioactivity

    International Nuclear Information System (INIS)

    Rapid technique for determining building material radioactivity graphically, using nomogram of known uranium (226Ra), thorium (232Th), potassium contents is suggested. Nomogram usage permits to replace labour-consuming calculations of radionuclide specific activity by formula with simple rule imposition. Determination errors don't exceed 1-2%. The nomogram may be easily constructed selecting ranges of radionuclide concentration variation ranges, which are the most characteristic for the work region, and calculating scale values for U, Th and K by formula. Distance from uranium activity scale to U and Th total activity scale as well as scale factor of total specific activity are calculated by formula

  15. An Unusual Case of Rapidly Progressive Hyperbilirubinemia

    Directory of Open Access Journals (Sweden)

    Kimberly M. Thornton

    2013-01-01

    Full Text Available We present an unusual case of hyperbilirubinemia with rapid early progression leading to bilirubin encephalopathy in a term neonate. Despite early recognition and intervention, the total serum bilirubin reached a maximum level of 39 mg/dL at 32 hours of life. Prior to an emergent exchange transfusion, the patient’s diagnostic evaluation was significant for Coombs-negative microangiopathic hemolytic anemia and thrombocytopenia. Further testing revealed a deficiency of ADAMTS13 protein, or von Willebrand factor-cleaving protease, a finding diagnostic of congenital thrombotic thrombocytopenic purpura, or Upshaw-Schulman syndrome. This rare disease is often misdiagnosed, especially in the newborn period.

  16. Rapid River Hatchery - Spring Chinook, Final Report

    International Nuclear Information System (INIS)

    This report presents the findings of the independent audit of the Rapid River Hatchery (Spring Chinook). The hatchery is located in the lower Snake River basin near Riggins Idaho. The hatchery is used for adult collection, egg incubation, and rearing of spring chinook. The audit was conducted in April 1996 as part of a two-year effort that will include 67 hatcheries and satellite facilities located on the Columbia and Snake River system in Idaho, Oregon, and Washington. The hatchery operating agencies include the US Fish and Wildlife Service, Idaho Department of Fish and Game, Oregon Department of Fish and Wildlife, and Washington Department of Fish and Wildlife

  17. Plant MAPK cascades: Just rapid signaling modules?

    KAUST Repository

    Boudsocq, Marie

    2015-08-27

    © 2015 Taylor & Francis Group, LLC. Abscisic acid (ABA) is a major phytohormone mediating important stress-related processes. We recently unveiled an ABA-activated MAPK signaling module constituted of MAP3K17/18-MKK3-MPK1/2/7/14. Unlike classical rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests that MAPKs can regulate both early and longterm plant stress responses.

  18. Rapid induction of false memory for pictures

    OpenAIRE

    Weinstein, Y

    2009-01-01

    In this thesis, a new procedure is proposed which achieves the rapid induction of false recognition memory for rich pictorial stimuli. Chapter 2 presents the basic three-step procedure in which participants study some pictures, imagine others in response to words, and perform a picture recognition test. Imagining pictures leads to a false alarm rate of 27% above baseline (Experiments 1a and 1b). In Chapter 3, a source monitoring test is used to demonstrate that this effect is not solely due t...

  19. Post liposuction infections by rapidly growing mycobacteria.

    Science.gov (United States)

    Zosso, Caroline; Lienhard, Reto; Siegrist, Hans H; Malinverni, Raffaele; Clerc, Olivier

    2015-02-01

    Rapidly growing mycobacteria (RGM) are recognized agents of surgical site infections. Recently, RGM skin and soft tissue infections have been increasingly reported. As symptoms, clinical signs and disease latency remain non-specific and microbiological detection requires targeted growth media, RGM diagnosis remains challenging for clinicians. Appropriate management is often delayed due to lack of awareness of these infections. RGM infections after plastic surgery have also been described in the setting of interventions performed in developing countries, a growing phenomenon commonly known as medical tourism. We describe a case of Mycobacterium chelonae/abscessus infection following liposuction and liposculpture procedures performed in the Dominican Republic and review the literature on this subject.

  20. Rapid thermal processing science and technology

    CERN Document Server

    Fair, Richard B

    1993-01-01

    This is the first definitive book on rapid thermal processing (RTP), an essential namufacturing technology for single-wafer processing in highly controlled environments. Written and edited by nine experts in the field, this book covers a range of topics for academics and engineers alike, moving from basic theory to advanced technology for wafer manufacturing. The book also provides new information on the suitability or RTP for thin film deposition, junction formation, silicides, epitaxy, and in situ processing. Complete discussions on equipment designs and comparisons between RTP and other

  1. Rapid Drop Dynamics During Superhydrophobic Condensation

    Science.gov (United States)

    Zhang, Xiaodong; Boreyko, Jonathan; Chen, Chuan-Hua

    2008-11-01

    Rapid drop motion is observed on superhydrophobic surfaces during condensation; condensate drops with diameter of order 10 μm can move at above 100G and 0.1 m/s. When water vapor condenses on a horizontal superhydrophobic surface, condensate drops move in a seemingly random direction. The observed motion is attributed to the energy released through coalescence of neighboring condensate drops. A scaling analysis captured the initial acceleration and terminal velocity. Our work is a step forward in understanding the dynamics of superhydrophobic condensation occurring in both natural water-repellant plants and engineered dropwise condensers.

  2. Smith Predictor Based Robust Rapid Tracking Controller

    Institute of Scientific and Technical Information of China (English)

    LIU Hongbin; HU Dejin

    2006-01-01

    Precise model is hard to get in real application, a Smith predictor based robust rapid tracking controller for inaccurate model is proposed. Zero phase error feedforward controller which increases system closed-loop dynamics and disturbance observer based Smith feedback control which diminishes model hysteresis and improves stability are integrated. This method is applied in the noncircular machining with piezoelectric ceramic driver. The simulation and experiment show that the performance robustness and stability are well balanced in bandwidth about 200 Hz. The controller can decrease system hysteresis and get good tracking performance for predefined square-wave input signal.

  3. Synchronous Routing for Personal Rapid Transit Pods

    OpenAIRE

    Mehdi Mrad; Olfa Chebbi; Mohamed Labidi; Mohamed Ali Louly

    2014-01-01

    Personal rapid transit (PRT) is a public and automated transport system in which a fleet of small driverless vehicles operate in order to transport passengers between a set of stations through a network of guided ways. Each customer is carried from one station to another directly with no stop in intermediate stations. This mode of transport can result in a high level of unused capacity due to the empty moves of the vehicles. In this paper, we model the problem of minimizing the energy consume...

  4. Rapid Cellular Turnover in Adipose Tissue

    OpenAIRE

    Alessandra Rigamonti; Kristen Brennand; Frank Lau; Cowan, Chad A.

    2011-01-01

    It was recently shown that cellular turnover occurs within the human adipocyte population. Through three independent experimental approaches — dilution of an inducible histone 2B-green fluorescent protein (H2BGFP), labeling with the cell cycle marker Ki67 and incorporation of BrdU — we characterized the degree of cellular turnover in murine adipose tissue. We observed rapid turnover of the adipocyte population, finding that 4.8% of preadipocytes are replicating at any time and that between 1–...

  5. Rapid Development of China's Offshore Oil Industry

    Institute of Scientific and Technical Information of China (English)

    Zhang Haimin

    2002-01-01

    @@ Founded on February 15, 1982, China National Offshore Oil Corporation (CNOOC) has experienced two decades of rapid development, in which the annual offshore oil production rose dramatically to 23.13 million tons in 2001 from 90,000 tons in 1982while the total assets jumped to 72 billion yuan from 2.8 billion yuan, but the total employees dropped to 21,000 people from 30,000. This offshore oil giant generated a profit of 9.2 billion yuan in 2001 and turned over 4 billion yuan in taxes to the State with the crude production cost lowered to US$9 per barrel.

  6. Partial Lipodystrophy and Rapidly Progressive Nephritis

    Directory of Open Access Journals (Sweden)

    Hasan Mjalli

    2001-01-01

    Full Text Available We report the association of partial lipodystrophy (PL and nephritis in an 11-year-old boy. He had symmetric absence of facial fat with retention of adipose tissue in the arms, chest, abdomen and hips associated with macroscopic hematuria, proteinuria combined with depression of the complement C3 level. The patient had rapidly progressive glomerulonephritis (RPGN and the histopathological study showed findings of mesangio-capillary glomerulonephritis (MCGN and crescents. We managed and followed up this patient for three years. At the last follow-up visit, he still has mild proteinuria and microscopic hematuria and stable renal function.

  7. Rapidly solidified titanium alloys by melt overflow

    Science.gov (United States)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III

    1989-01-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  8. Rapid Tooling Technique Based on Stereolithograph Prototype

    Institute of Scientific and Technical Information of China (English)

    丁浩; 狄平; 顾伟生; 朱世根

    2001-01-01

    Rapid tooling technique based on the sterelithograph prototype is investigated. The epoxy tooling technological process was elucidated. It is analyzed in detail that the epoxy resin formula is easy to cast, curing process, and release agents. The transitional plaster model is also proposed. The mold to encrust mutual.inductors with epoxy and mold to inject plastic soapboxes was made with the technique The tooling needs very little time and cost, for the process is only to achieve the nice replica of the prototype. It is benefit for the trial and small batch of production.

  9. Rapid Prototyping: Technologies, Materials and Advances

    Directory of Open Access Journals (Sweden)

    Dudek P.

    2016-06-01

    Full Text Available In the context of product development, the term rapid prototyping (RP is widely used to describe technologies which create physical prototypes directly from digital data. Recently, this technology has become one of the fastest-growing methods of manufacturing parts. The paper provides brief notes on the creation of composites using RP methods, such as stereolithography, selective laser sintering or melting, laminated object modelling, fused deposition modelling or three-dimensional printing. The emphasis of this work is on the methodology of composite fabrication and the variety of materials used in these technologies.

  10. Titanite and apatite fission track analyses on basement rocks of central-southern Madagascar: constraints on exhumation and denudation rates along the eastern rift shoulder of the Morondava basin

    Science.gov (United States)

    Emmel, B.; Jacobs, J.; Razakamanana, T.

    2004-03-01

    Titanite and apatite fission-track (FT) thermochronology from basement rocks in central-southern Madagascar reveals a protracted post Late Neoproterozoic/Early Cambrian history of extensional tectonism, denudation and sedimentation. Titanite FT ages range between 379 ± 38 and 276 ± 17 Ma and apatite FT ages vary between 379 ± 19 and 150 ± 8 Ma. Combined titanite and apatite FT data from the western palaeo margin of Madagascar suggest denudation rates of ˜200-100 mMa -1 during Carboniferous times. The Late Neoproterozoic/Early Cambrian Ejeda shear zone was probably reactivated during this time. In contrast, for the same period denudation rates inland are ˜110-25 mMa -1. During Permo-Triassic rifting, areas that previously underwent fast denudation were buried by sedimentary cover up to ˜4.5 km. At this time, a graben developed along the transcontinental Bongolava-Ranotsara shear zone (BRSZ). Graben faults are exposed at the northeastern graben shoulder. Identical titanite and apatite FT ages close to the BRSZ indicate rapid cooling associated with fluid circulation during Early Permian times. The initial Gondwana break-up during Middle Jurassic times and the drift of Madagascar along the Davie transform fault did not significantly influence the FT data and had only minor geomorphic impact in the study area. Only the far southwestern part of the island is characterised by a higher degree of denudation (max. ˜3.5 km) during Early Jurassic times. Early Cretaceous and Cenozoic volcanic activity affected the apatite FT data from southern Madagascar. Modelled time-temperature ( T- t) paths argue for a reheating of samples from southern Madagascar to temperatures of ˜60-80 °C during the times of magmatism, before final cooling to surface temperatures.

  11. Forward jets and large rapidity gaps

    CERN Document Server

    Campanelli, Mario

    2015-01-01

    Hadronic jets are extremely abundant at the LHC, and testing QCD in various corners of phase-space is important to understand backgrounds and some specific signatures of new physics. In this article, various measurements aiming at probing QCD in configurations where the theory modeling become challenging are presented. Azimuthal angle de-correlations are sensitive to hard as well as soft QCD emission, and in most of the events jets are produced in a back-to-back configuration. Events where jets have a large rapidity separation are also rare, and those without additional radiation between the jets are exponentially suppressed. The modeling of radiation between very forward and backward jets is complicated, and may require theoretical tools different with respect to those normally used for central, high-pt events. Observables can be created that are sensitive to all these effects, like the study of azimuthal angle de-correlations between events where the two leading jets have large rapidity separations. The two...

  12. Light curves from rapidly rotating neutron stars

    CERN Document Server

    Numata, Kazutoshi

    2010-01-01

    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitudes to disturb the spot. For a $l'=m$ core $r$-mode, the oscillation frequency $\\omega\\approx2m\\Omega/[l'(l'+1)]$ defined in the co-rotating frame of the star will be detected by a distant observer, where $l'$ and $m$ are respectively the spherical harmonic degree and the azimuthal wave number of the mode, and $\\Omega$ is the spin frequency of the star. In a linear theory of oscillation, using a parameter $A$ we parametrize the mode amplitudes such that ${\\rm max}\\left(|\\xi_\\theta|,|\\xi_\\phi|\\right)/R=A$ at the surface, w...

  13. Rapid identification of microorganisms by intrinsic fluorescence

    Science.gov (United States)

    Bhatta, Hemant; Goldys, Ewa M.; Learmonth, Robert

    2005-03-01

    Microbial contamination has serious consequences for the industries that use fermentation processes. Common contaminants such as faster growing lactic acid bacteria or wild yeast can rapidly outnumber inoculated culture yeast and produce undesirable end products. Our study focuses on a rapid method of identification of such contaminants based on autofluorescence spectroscopy of bacterial and yeast species. Lactic acid bacteria (Lac-tobacillus casei), and yeast (Saccharomyces cerevisiae) were cultured under controlled conditions and studied for variations in their autofluorescence. We observed spectral differences in the spectral range representative of tryptophan residues of proteins, with excitation at 290 nm and emission scanned in the 300 nm - 440 nm range. Excitation scans between 240 nm and 310 nm were also performed for the emission at 340 nm. Moreover, we observed clearly pronounced differences in the excitation and emission in the visible range, with 410 nm excitation. These results demonstrate that bacterial and yeast species can be differentiated using their intrinsic fluorescence both in UV and in the visible region. The comparative spectroscopic study of selected strains of Saccharomyces yeast showed clear differences between strains. Spectrally-resolved laser scanning microscopy was carried out to link the results obtained using ensembles of cells with spectral properties of individual cells. Strongly fluorescent subpopulation were observed for all yeast strains with excitation at 405 nm. The fluorescence spectra showed variations correlated with cell brightness. The presented results demonstrate that using autofluorescence, it is possible to differentiate between yeast and lactic acid bacteria and between different yeast species.

  14. Rapid neural discrimination of communicative gestures.

    Science.gov (United States)

    Redcay, Elizabeth; Carlson, Thomas A

    2015-04-01

    Humans are biased toward social interaction. Behaviorally, this bias is evident in the rapid effects that self-relevant communicative signals have on attention and perceptual systems. The processing of communicative cues recruits a wide network of brain regions, including mentalizing systems. Relatively less work, however, has examined the timing of the processing of self-relevant communicative cues. In the present study, we used multivariate pattern analysis (decoding) approach to the analysis of magnetoencephalography (MEG) to study the processing dynamics of social-communicative actions. Twenty-four participants viewed images of a woman performing actions that varied on a continuum of communicative factors including self-relevance (to the participant) and emotional valence, while their brain activity was recorded using MEG. Controlling for low-level visual factors, we found early discrimination of emotional valence (70 ms) and self-relevant communicative signals (100 ms). These data offer neural support for the robust and rapid effects of self-relevant communicative cues on behavior.

  15. Laser rapid manufacturing of Colmonoy-6 components

    Science.gov (United States)

    Paul, C. P.; Jain, A.; Ganesh, P.; Negi, J.; Nath, A. K.

    2006-10-01

    This paper introduces a new manufacturing technique for the fabrication of Colmonoy-6 components using laser rapid manufacturing (LRM). LRM is a upcoming rapid manufacturing technology, being developed at various laboratories around the world. It is similar to laser cladding at the process level with different end applications. In general, laser cladding technique is used to deposit material on the substrate either to improve the surface properties or to refurbish the worn out parts, while LRM is capable of near net shaping the components by layer-by-layer deposition of the material directly from CAD model. In the present study, a high power continuous wave (CW) CO 2 laser system, integrated with a co-axial powder-feeding system and three-axis workstation was used. The effect of processing parameters during multi-layer deposition of Colmonoy-6 has been studied and optimized to fabricate about a dozen bushes. Thus fabricated bushes were finally machined and ground to achieve the desired dimensions and surface finish. These bushes were tested for non-destructive testing (like-ultrasonic testing, Dye-penetrant testing), metallographic examinations, micro-hardness measurement, X-ray diffraction and thermal ageing. Results compared well with those fabricated by deposition of Colmonoy-6 on austenitic stainless steel rods using gas Tungsten arc welding (GTAW). Thus, the new manufacturing technique not only produced quality product, but also minimized machining of hard-faced material and brought significant saving of time and costly Colmonoy-6 material.

  16. Ultra-Rapid Vision in Birds.

    Science.gov (United States)

    Boström, Jannika E; Dimitrova, Marina; Canton, Cindy; Håstad, Olle; Qvarnström, Anna; Ödeen, Anders

    2016-01-01

    Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey. PMID:26990087

  17. Ultra-Rapid Vision in Birds

    Science.gov (United States)

    Boström, Jannika E.; Dimitrova, Marina; Canton, Cindy; Håstad, Olle; Qvarnström, Anna; Ödeen, Anders

    2016-01-01

    Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey. PMID:26990087

  18. Ultra-Rapid Vision in Birds.

    Directory of Open Access Journals (Sweden)

    Jannika E Boström

    Full Text Available Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively, which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey.

  19. Rapid molecular detection of Lujo virus RNA.

    Science.gov (United States)

    Atkinson, Barry; Chamberlain, John; Dowall, Stuart D; Cook, Nicola; Bruce, Christine; Hewson, Roger

    2014-01-01

    Lujo virus is an emerging arenavirus circulating in Southern Africa. Although to date there has only been a single outbreak of the novel haemorrhagic disease resulting from human infection with this virus, the case-fatality rate of exposed individuals, including nosocomial transmission, was 80%. The ability to identify viral haemorrhagic fevers accurately, especially those capable of nosocomial transmission, is of critical importance. Timely identification of these diseases allow medical professionals to isolate patients and implement barrier nursing techniques in order to prevent onward transmission of the virus. While rapid diagnostic methods are published for most viral haemorrhagic fevers, at present there are no such virus specific protocols for Lujo haemorrhagic fever. This report details the first set of diagnostic molecular assays designed to identify Lujo viral RNA rapidly, and demonstrates the potential functionality of these assays for use in the clinical setting. Although these assays have been designed and validated against a solitary isolate of Lujo virus, this represents the entirety of strains detected to date, and offer quick, cheap and easy methods for use in diagnostic laboratories.

  20. Organic carbon biostimulates rapid rhizodegradation of perchlorate.

    Science.gov (United States)

    Yifru, Dawit D; Nzengung, Valentine A

    2008-12-01

    Previous hydroponics and field studies identified phytodegradation and rhizodegradation as the two main mechanisms by which plants metabolize perchlorate. Plant uptake and phytodegradation of perchlorate is a slower and undesired process that poses ecological risks resulting from phytoaccumulation of some fraction of the perchlorate. Meanwhile, rhizodegradation is a more rapid and favored process involving perchlorate-degrading bacteria utilizing dissolved organic carbon (DOC) as a carbon and energy (electron) source to rapidly degrade perchlorate to innocuous chloride. In the present study, rhizodegradation of perchlorate by willow trees (Salix nigra) was biostimulated using electron sources obtained from natural and artificial carbon sources. In bioreactors provided with carbon sources as 500 mg/L DOC, 25 to 40 mg/L of initial perchlorate concentrations were removed to below the ion chromatography method detection limit of 2 microg/L in approximately 9 d. For planted controls provided with no electron donors, the time required for the complete removal of the same doses of perchlorate was up to 70 d. Enhancement of rhizodegradation by organic carbon reduced the phytoaccumulated fraction of perchlorate by an order of magnitude from approximately 430 to 20 mg/kg. The implication of the present study is that the high fraction uptake and phytoaccumulation of perchlorate in agricultural products and the recycling of perchlorate into the ecosystem can be significantly curtailed by supplying electron donors derived from organic carbon sources to the root zone of plants. PMID:18593217

  1. Ultra-Rapid Vision in Birds.

    Science.gov (United States)

    Boström, Jannika E; Dimitrova, Marina; Canton, Cindy; Håstad, Olle; Qvarnström, Anna; Ödeen, Anders

    2016-01-01

    Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey.

  2. Transient burnout under rapid flow reduction condition

    International Nuclear Information System (INIS)

    Burnout characteristics were experimentally studied using uniformly heated tube and annular test sections under rapid flow reduction conditions. Observations indicated that the onset of burnout under a flow reduction transient is caused by the dryout of a liquid film on the heated surface. The decrease in burnout mass velocity at the channel inlet with increasing flow reduction rate is attributed to the fact that the vapor flow rate continues to increase and sustain the liquid film flow after the inlet flow rate reaches the steady-state burnout flow rate. This is because the movement of the boiling boundary cannot keep up with the rapid reduction of inlet flow rate. A burnout model for the local condition could be applied to the burnout phenomena with the flow reduction under pressures of 0.5 ∼ 3.9 MPa and flow reduction rates of 0.6 ∼ 35 %/s. Based on this model, a method to predict the burnout time under a flow reduction condition was presented. The calculated burnout times agreed well with experimental results obtained by some investigators. (author)

  3. Rapid Detection of the Varicella Zoster Virus

    Science.gov (United States)

    Lewis, Michelle P.; Harding, Robert

    2011-01-01

    1.Technology Description-Researchers discovered that when the Varicella Zoster Virus (VZV) reactivates from latency in the body, the virus is consistently present in saliva before the appearance of skin lesions. A small saliva sample is mixed with a specialized reagent in a test kit. If the virus is present in the saliva sample, the mixture turns a red color. The sensitivity and specificity emanates from an antibody-antigen reaction. This technology is a rapid, non-invasive, point of-of-care testing kit for detecting the virus from a saliva sample. The device is easy to use and can be used in clinics and in remote locations to quickly detect VZV and begin treatment with antiviral drugs. 2.Market Opportunity- RST Bioscience will be the first and only company to market a rapid, same day test kit for the detection of VZV in saliva. The RST detection test kit will have several advantages over existing, competitive technology. The test kit is self contained and laboratory equipment is not required for analysis of the sample. Only a single saliva sample is required to be taken instead of blood or cerebral spinal fluid. The test kit is portable, sterile and disposable after use. RST detection test kits require no electrical power or expensive storage equipment and can be used in remote locations. 3.Market Analysis- According to the CDC, it is estimated that 1 million cases of shingles occur each year in the U.S. with more than half over the age of sixty. There is a high demand for rapid diagnostics by the public. The point-of-care testing (POCT) market is growing faster than other segments of in vitro diagnostics. According to a July 2007 InteLab Corporation industry report the overall market for POCT was forecast to increase from $10.3 billion in 2005 to $18.7 billion by 2011. The market value of this test kit has not been determined. 4.Competition- The VZV vaccine prevents 50% of cases and reduces neuralgia by 66%. The most popular test detects VZV-specific IgM antibody

  4. The Rapid Ice Sheet Change Observatory (RISCO)

    Science.gov (United States)

    Morin, P.; Howat, I. M.; Ahn, Y.; Porter, C.; McFadden, E. M.

    2010-12-01

    The recent expansion of observational capacity from space has revealed dramatic, rapid changes in the Earth’s ice cover. These discoveries have fundamentally altered how scientists view ice-sheet change. Instead of just slow changes in snow accumulation and melting over centuries or millennia, important changes can occur in sudden events lasting only months, weeks, or even a single day. Our understanding of these short time- and space-scale processes, which hold important implications for future global sea level rise, has been impeded by the low temporal and spatial resolution, delayed sensor tasking, incomplete coverage, inaccessibility and/or high cost of data available to investigators. New cross-agency partnerships and data access policies provide the opportunity to dramatically improve the resolution of ice sheet observations by an order of magnitude, from timescales of months and distances of 10’s of meters, to days and meters or less. Advances in image processing technology also enable application of currently under-utilized datasets. The infrastructure for systematically gathering, processing, analyzing and distributing these data does not currently exist. Here we present the development of a multi-institutional, multi-platform observatory for rapid ice change with the ultimate objective of helping to elucidate the relevant timescales and processes of ice sheet dynamics and response to climate change. The Rapid Ice Sheet Observatory (RISCO) gathers observations of short time- and space-scale Cryosphere events and makes them easily accessible to investigators, media and general public. As opposed to existing data centers, which are structured to archive and distribute diverse types of raw data to end users with the specialized software and skills to analyze them, RISCO focuses on three types of geo-referenced raster (image) data products in a format immediately viewable with commonly available software. These three products are (1) sequences of images

  5. Methods and compositions for rapid thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher

    2015-10-27

    The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.

  6. Acute glomerulonephritis, rapidly progressive emphasis on commitment

    Directory of Open Access Journals (Sweden)

    Adolfo León Castro

    2011-11-01

    Full Text Available Acute glomerulonephritis (GNA is a wide group of diseases with the common characteristics of abrupt onset and proliferation of endocapillary glomerular cells. Clinically, they usually manifest as acute nephritic syndrome: hematuria, acute renal failure, hypertension and mild proteinuria, although they can appear as recurrent hematuria. GNA can be present in association with a variety of bacterial and viral infections, but in most cases the initial antigenic initiating stimulus is unknown. Patients with rapidly progressive glomerulonephritis often present acute onset of manifestations of nephritis, such as azotemia, oliguria, edema, hypertension, proteinuria, and hematuria with «active» urine sediment that often contains red blood cell casts, pigmented casts, and cellular debris. This article, aimed at all primary care staff and seeking to increase their awareness of this disease, discusses in more detail the clinical, pathogenesis, pathology, and treatments available from one of the glomerulonephritis with greater impact on survival patient.

  7. Methods and compositions for rapid thermal cycling

    Science.gov (United States)

    Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher

    2015-10-27

    The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.

  8. China's Wind Power in Rapid Progressing

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    China's wind power has gone through an exploring course of 20years. At present, it is on the fast track under the support of the state's preferential policies concerned. The various wind power development areas in China have made rapid progress and put forward their own thinking of developing wind energy.%经过20年的探索和发展,中国风电在国家相关优惠政策的支持下,现已走上了快速发展的道路。各个风电开发地区已经取得了长足的进步,并各自提出了今后发展风电的设想。

  9. Motion Analysis Based on Invertible Rapid Transform

    Directory of Open Access Journals (Sweden)

    J. Turan

    1999-06-01

    Full Text Available This paper presents the results of a study on the use of invertible rapid transform (IRT for the motion estimation in a sequence of images. Motion estimation algorithms based on the analysis of the matrix of states (produced in the IRT calculation are described. The new method was used experimentally to estimate crowd and traffic motion from the image data sequences captured at railway stations and at high ways in large cities. The motion vectors may be used to devise a polar plot (showing velocity magnitude and direction for moving objects where the dominant motion tendency can be seen. The experimental results of comparison of the new motion estimation methods with other well known block matching methods (full search, 2D-log, method based on conventional (cross correlation (CC function or phase correlation (PC function for application of crowd motion estimation are also presented.

  10. Rapid bioassay for oil-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Ashworth, J. [ALS Environmental, Edmonton, AB (Canada); Oosterbroek, L. [HydroQual, Calgary, AB (Canada)

    2010-07-01

    This PowerPoint presentation described a study conducted to develop a rapid bioassay for soils contaminated with oil. The bioassay method was designed for a weight of evidence (WoE) approach and eco-contact guideline derivation protocol. Microtox bioassays were conducted on cyclodextrin extracts of soil quantified by solvent extraction and gas chromatography. The method was demonstrated using straight {beta}-cyclodextrin soil extracts and activated {beta}-cyclodextrin soil extracts. An analysis of the methods showed that the activation step weakens or breaks the cyclodextrin and polycyclic hydrocarbon (PHC) inclusion complex. The released PHC became toxic to the microtox organism. Results from the bioassays were then correlated with earthworm reproduction bioassay results. tabs., figs.

  11. Rapid induction of false memory for pictures.

    Science.gov (United States)

    Weinstein, Yana; Shanks, David R

    2010-07-01

    Recognition of pictures is typically extremely accurate, and it is thus unclear whether the reconstructive nature of memory can yield substantial false recognition of highly individuated stimuli. A procedure for the rapid induction of false memories for distinctive colour photographs is proposed. Participants studied a set of object pictures followed by a list of words naming those objects, but embedded in the list were names of unseen objects. When subsequently shown full colour pictures of these unseen objects, participants consistently claimed that they had seen them, while discriminating with high accuracy between studied pictures and new pictures whose names did not appear in the misleading word list. These false memories can be reported with high confidence as well as the feeling of recollection. This new procedure allows the investigation of factors that influence false memory reports with ecologically valid stimuli and of the similarities and differences between true and false memories. PMID:20623419

  12. Rapid Determination of Silicon Content in Rice

    Institute of Scientific and Technical Information of China (English)

    DAI Wei-min; ZHANG Ke-qin; DUAN Bin-wu; SUN Cheng-xiao; ZHENG Kang-le; CAI Run; ZHUANG Jie-yun

    2005-01-01

    A method for rapid determination of silicon content in rice was introduced. The reliability of this method was verified byusing a recombinant inbred line (RIL) population of rice cross Zhenshan 97B / Milyang 46. Two hundred and forty-nine RILs weretransplanted in two replications. Simple correlation coefficients on the silicon content in the hull, flag leaf and stem in rice betweenduplicate samples of 498 rice materials were 0.97954, 0.97026 and 0.98848, respectively. Ten representative samples wereselected for measurement using the high-temperature alkaline fusion method. Simple correlation coefficient between the siliconcontents determined by the high-temperature alkaline fusion method and by the present method is 0.9993.

  13. World NGL markets continue rapid expansion

    International Nuclear Information System (INIS)

    The international LPG industry has expanded rapidly during the 1990s and undergone significant changes. LPG consumption has expanded at nearly twice the rate of world petroleum demand. In particular, LPG use in residential and commercial markets has more than doubled in many developing countries. Markets for LPG and other petroleum products have been opened in many countries, accelerating demand growth and creating investment opportunities in all downstream segments. This has led to an overall strengthening of global LPG pricing and the development of many new export gas-processing projects. The paper discusses world LPG demand in residential and commercial markets and in petrochemicals, world LPG supply, regional increases, international trade, the US situation in natural gas, NGL supply, and NGL demand

  14. Quadrupole magnet for a rapid cycling synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Witte, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    Rapid Cycling Synchrotrons (RCS) feature interleaved warm and cold dipole magnets; the field of the warm magnets is used to modulate the average bending field depending on the particle energy. It has been shown that RCS can be an attractive option for fast acceleration of particles, for example, muons, which decay quickly. In previous studies it was demonstrated that in principle warm dipole magnets can be designed which can provide the required ramp rates, which are equivalent to frequencies of about 1 kHz. To reduce the losses it is beneficial to employ two separate materials for the yoke; it was also shown that by employing an optimized excitation coil geometry the eddy current losses are acceptable. In this paper we show that the same principles can be applied to quadrupole magnets targeting 30 T/m with a repetition rate of 1kHz and good field quality.

  15. Rapid deployable global sensing hazard alert system

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph V; Tibrea, Steven L; Shull, Davis J; Coleman, Jerry T; Shuler, James M

    2015-04-28

    A rapid deployable global sensing hazard alert system and associated methods of operation are provided. An exemplary system includes a central command, a wireless backhaul network, and a remote monitoring unit. The remote monitoring unit can include a positioning system configured to determine a position of the remote monitoring unit based on one or more signals received from one or more satellites located in Low Earth Orbit. The wireless backhaul network can provide bidirectional communication capability independent of cellular telecommunication networks and the Internet. An exemplary method includes instructing at least one of a plurality of remote monitoring units to provide an alert based at least in part on a location of a hazard and a plurality of positions respectively associated with the plurality of remote monitoring units.

  16. Synchronous Routing for Personal Rapid Transit Pods

    Directory of Open Access Journals (Sweden)

    Mehdi Mrad

    2014-01-01

    Full Text Available Personal rapid transit (PRT is a public and automated transport system in which a fleet of small driverless vehicles operate in order to transport passengers between a set of stations through a network of guided ways. Each customer is carried from one station to another directly with no stop in intermediate stations. This mode of transport can result in a high level of unused capacity due to the empty moves of the vehicles. In this paper, we model the problem of minimizing the energy consumed by the PRT system while assuming predeterministic list of orders; then we solve it using some constructive heuristics. Experiments are run on 1320 randomly generated test problems with various sizes. Our algorithms are shown to give good results over large trip instances.

  17. Metals Production Requirements for Rapid Photovoltaics Deployment

    CERN Document Server

    Kavlak, Goksin; Jaffe, Robert L; Trancik, Jessika E

    2015-01-01

    If global photovoltaics (PV) deployment grows rapidly, the required input materials need to be supplied at an increasing rate. In this paper, we quantify the effect of PV deployment levels on the scale of metals production. For example, we find that if cadmium telluride {copper indium gallium diselenide} PV accounts for more than 3% {10%} of electricity generation by 2030, the required growth rates for the production of indium and tellurium would exceed historically-observed production growth rates for a large set of metals. In contrast, even if crystalline silicon PV supplies all electricity in 2030, the required silicon production growth rate would fall within the historical range. More generally, this paper highlights possible constraints to the rate of scaling up metals production for some PV technologies, and outlines an approach to assessing projected metals growth requirements against an ensemble of past growth rates from across the metals production sector. The framework developed in this paper may be...

  18. Rapid prototyping of ossicular replacement prostheses

    Science.gov (United States)

    Ovsianikov, A.; Chichkov, B.; Adunka, O.; Pillsbury, H.; Doraiswamy, A.; Narayan, R. J.

    2007-05-01

    Materials used in ossicular replacement prostheses must demonstrate appropriate biological compatibility, acoustic transmission, stability, and stiffness properties. Prostheses prepared using Teflon ®, titanium, Ceravital and other conventional materials have demonstrated several problems, including migration, perforation of the tympanic membrane, difficulty in shaping the prostheses, and reactivity with the surrounding tissues. We have used two-photon polymerization for rapid prototyping of Ormocer ® middle-ear bone replacement prostheses. Ormocer ® surfaces fabricated using two-photon polymerization exhibited acceptable cell viability and cell growth profiles. The Ormocer ® prosthesis was able to be inserted and removed from the site of use in the frozen human head without fracture. Our results demonstrate that two-photon polymerization is able to create ossicular replacement prostheses and other medical devices with a larger range of sizes, shapes and materials than other microfabrication techniques.

  19. Rapid adaptation to foreign-accented English

    Science.gov (United States)

    Clarke, Constance M.; Garrett, Merrill F.

    2004-12-01

    This study explored the perceptual benefits of brief exposure to non-native speech. Native English listeners were exposed to English sentences produced by non-native speakers. Perceptual processing speed was tracked by measuring reaction times to visual probe words following each sentence. Three experiments using Spanish- and Chinese-accented speech indicate that processing speed is initially slower for accented speech than for native speech but that this deficit diminishes within one minute of exposure. Control conditions rule out explanations for the adaptation effect based on practice with the task and general strategies for dealing with difficult speech. Further results suggest that adaptation can occur within as few as two to four sentence-length utterances. The findings emphasize the flexibility of human speech processing and require models of spoken word recognition that can rapidly accommodate significant acoustic-phonetic deviations from native language speech patterns. .

  20. Rapid changes in night eating: considering mechanisms.

    Science.gov (United States)

    Stunkard, A; Lu, X-Y

    2010-01-01

    This paper considers possible mechanisms for the Night Eating Syndrome (NES). NES is a disorder characterized by a delay in the circadian rhythm of meals and of several neuroendocrine factors. The disorder occurs in genetically vulnerable people when exposed to stress. No convincing mechanism of the NES has been reported until now. To search for the mechanisms of NES, the long term treatment of two highly perceptive patients with rapid onset of the disorder are described. Disruption of three neuroendocrine systems compatible with these histories are discussed: the glucocorticoid system, the melanocortin [corrected] system, and the serotonergic system. Current evidence favors the serotonergic system and this view is strongly supported by the great effectiveness of selective serotonin reuptake inhibitors (SSRIs) in the treatment of NES. PMID:20571317

  1. Obliquity Variations of a Rapidly Rotating Venus

    Science.gov (United States)

    Quarles, Billy L.; Barnes, Jason W.; Lissauer, Jack J.; Chambers, John E.; Hedman, Matthew M.

    2016-05-01

    Venus clearly differs from Earth in terms of its spin and atmospheric composition, where the former is controlled by solid-body and atmospheric thermal tides. However, this may have been different during earlier stages of planetary evolution, when the Sun was fainter and the Venusian atmosphere was less massive. We investigate how the axial tilt, or obliquity, would have varied during this epoch considering a rapidly rotating Venus. Through numerical simulation of an ensemble of hypothetical Early Venuses, we find the obliquity variation to be simpler than a Moonless Earth (Lissauer et al., 2012). Most low-obliquity Venuses show very low total obliquity variability comparable to that of the real Moon-influenced Earth.

  2. Embryo culture and rapid propagation of Syringa

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li; DAI Li-min; SU Bao-ling

    2003-01-01

    Embryo of lilacs (Syringa L) culture in vitro and the rapid propagation were studied. The orthogonal experiments, including the selection of basal medium, embryo age and other factors such as sugar, benzyladenine (BA), naphthalene acetic acid (NAA) and glutamine (Gln), were carried out. The results indicated that the optimal medium for embryo culture was Monnier medium supplemented with NAA (0.001 mg@L-1), BA (0.1 mg@L-1), sugar (50 g@L-1), and Gln (400 mg@L-1), with a germination rate of 91.7% at least; the optimal embryo age was 50 d; and Gln had significant effects on the germination rate of embryo. Moreover, the optimal medium for subculture was MS+BA (2 mg@L-1)+NAA (0.001 mg@L-1)+Gln (0.5 mg@L-1), with the propagation coefficient of 3.6 at least.

  3. Chandra Data Reveal Rapidly Whirling Black Holes

    Science.gov (United States)

    2008-01-01

    A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly. The whirling of these giant black holes drives powerful jets that pump huge amounts of energy into their environment and affects galaxy growth. A team of scientists compared leading theories of jets produced by rotating supermassive black holes with Chandra data. A sampling of nine giant galaxies that exhibit large disturbances in their gaseous atmospheres showed that the central black holes in these galaxies must be spinning at near their maximum rates. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Erratic Black Hole Regulates Itself "We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light," said Rodrigo Nemmen, a visiting graduate student at Penn State University, and lead author of a paper on the new results presented at American Astronomical Society in Austin, Texas. The research reinforces other, less direct methods previously used which have indicated that some stellar and supermassive black holes are spinning rapidly. According to Einstein's theory, a rapidly spinning black hole makes space itself rotate. This effect, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet. Computer simulations by other authors have suggested that black holes may acquire their rapid spins when galaxies merge, and through the accretion of gas from their surroundings. "Extremely fast spin might be very common for large

  4. Rapid and precise measurement of flatband voltage

    Science.gov (United States)

    Li, S. P.; Ryan, M.; Bates, E. T.

    1976-01-01

    The paper outlines the design, principles of operation, and calibration of a five-IC network intended to give a rapid, precise, and automatic determination of the flatband voltage of MOS capacitors. The basic principle of measurement is to compare the analog output voltage of a capacitance meter - which is directly proportional to the capacitance being measured - with a preset or dialed-in voltage proportional to the calculated flatband capacitance by means of a comparator circuit. The bias to the MOS capacitor supplied through the capacitance meter is provided by a ramp voltage going from a negative toward a positive voltage level and vice versa. The network employs two monostable multivibrators for reading and recording the flatband voltage and for resetting the initial conditions and restarting the ramp. The flatband voltage can be held and read on a digital voltmeter.

  5. Rapid variability of extragalactic radio sources

    Energy Technology Data Exchange (ETDEWEB)

    Quirrenbach, A.; Witzel, A.; Krichbaum, T.; Hummel, C.A.; Alberdi, A.; Schalinski, C.

    1989-02-02

    Since its discovery more than 20 years ago, variability of extragalactic radio sources on timescales of weeks to years has been the subject of many investigations. We have examined the variability of these sources on timescales of hours at wavelengths of 6 and 11 cm using the 100-m telescope of the Max-Planck-Institut fuer Radioastronomie and report the results for two sources. The quasar QSO0917 + 62 showed variations with amplitudes of up to 23% in /similar to/ 24 hours, which were correlated at the two wavelengths; in the BL Lac object 0716 + 71 we found variations with amplitudes of 7-11%. We discuss intrinsic effects, gravitational lensing and scattering in the interstellar medium as possible explanations for rapid radio variability.

  6. Plant fitness in a rapidly changing world.

    Science.gov (United States)

    Anderson, Jill T

    2016-04-01

    81 I. 81 II. 82 III. 84 IV. 84 V. 85 85 References 85 SUMMARY: Modern reliance on fossil fuels has ushered in extreme temperatures globally and abnormal precipitation patterns in many regions. Although the climate is changing rapidly, other agents of natural selection such as photoperiod remain constant. This decoupling of previously reliable environmental cues shifts adaptive landscapes, favors novel suites of traits and likely increases the extinction risk of local populations. Here, I examine the fitness consequences of changing climates. Meta-analyses demonstrate that simulated future climates depress viability and fecundity components of fitness for native plant species in the short term, which could reduce population growth rates. Contracting populations that cannot adapt or adjust plastically to new climates might not be capable of producing sufficient migrants to track changing conditions. PMID:26445400

  7. Rapid assessment of dietary calcium intake.

    Science.gov (United States)

    Nordblad, Mikaela; Graham, Fiona; Mughal, M Zulf; Padidela, Raja

    2016-07-01

    A five-food item food frequency questionnaire (FFQ) and a 3-day food diary (3DFD) were used to estimate daily dietary calcium (Ca) intake in 32 patients aged 1-17 years. Median and IQR of Ca intake from 3DFD was 840 mg and 438 mg while from FFQ it was 700 mg and 987 mg, respectively. The non-parametrical Bland-Altman limits of agreement plot between two methods showed that most of the values fell between the limits of agreement at +794 mg and -388 mg. The FFQ had a specificity of 93% in identifying children who consumed inadequate amount of dietary Ca and a sensitivity of 78% in identifying children whose dietary Ca intake exceeded UK's Reference Nutrient Intake. Thus the FFQ allows rapid estimation of children with low daily dietary Ca intake in the clinic setting; however it does not replace 3DFD. PMID:26662924

  8. Crowdsourced Translation for Rapid Internationalization in Cyberspace

    DEFF Research Database (Denmark)

    Tran, Yen; Yonatany, Moshe; Mahnke, Volker

    2016-01-01

    This paper explores how Facebook effectively used crowdsourced translation to accelerate its rapid internationalization. We apply the learning perspective of internationalization theory to unpack what the firm learned in order to mobilize crowd-based knowledge to facilitate internationalization...... in the virtual context, and how it did so. Increasingly, global activities are conducted in virtual space and virtual markets and thus the paper offers insights into successful expansion in this new terrain. The findings highlight two key points: (1) the firm used cognitive/explicit learning to acquire external...... of internationally dispersed users – the “crowd” – to accelerate its internationalization in cyberspace. This empirical study extends internationalization theory regarding knowledge and organizational learning....

  9. Rapid virtual stenting for intracranial aneurysms

    Science.gov (United States)

    Zhao, Liang; Chen, Danyang; Chen, Zihe; Wang, Xiangyu; Paliwal, Nikhil; Xiang, Jianping; Meng, Hui; Corso, Jason J.; Xu, Jinhui

    2016-03-01

    The rupture of Intracranial Aneurysms is the most severe form of stroke with high rates of mortality and disability. One of its primary treatments is to use stent or Flow Diverter to divert the blood flow away from the IA in a minimal invasive manner. To optimize such treatments, it is desirable to provide an automatic tool for virtual stenting before its actual implantation. In this paper, we propose a novel method, called ball-sweeping, for rapid virtual stenting. Our method sweeps a maximum inscribed sphere through the aneurysmal region of the vessel and directly generates a stent surface touching the vessel wall without needing to iteratively grow a deformable stent surface. Our resulting stent mesh has guaranteed smoothness and variable pore density to achieve an enhanced occlusion performance. Comparing to existing methods, our technique is computationally much more efficient.

  10. Rapid surface sampling and archival record system

    Energy Technology Data Exchange (ETDEWEB)

    Barren, E.; Penney, C.M.; Sheldon, R.B. [GE Corporate Research and Development Center, Schenectady, NY (United States)] [and others

    1995-10-01

    A number of contamination sites exist in this country where the area and volume of material to be remediated is very large, approaching or exceeding 10{sup 6} m{sup 2} and 10{sup 6} m{sup 3}. Typically, only a small fraction of this material is actually contaminated. In such cases there is a strong economic motivation to test the material with a sufficient density of measurements to identify which portions are uncontaminated, so extensively they be left in place or be disposed of as uncontaminated waste. Unfortunately, since contamination often varies rapidly from position to position, this procedure can involve upwards of one million measurements per site. The situation is complicated further in many cases by the difficulties of sampling porous surfaces, such as concrete. This report describes a method for sampling concretes in which an immediate distinction can be made between contaminated and uncontaminated surfaces. Sample acquisition and analysis will be automated.

  11. Rapidly Moving Divertor Plates In A Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    S. Zweben

    2011-05-16

    It may be possible to replace conventional actively cooled tokamak divertor plates with a set of rapidly moving, passively cooled divertor plates on rails. These plates would absorb the plasma heat flux with their thermal inertia for ~10-30 sec, and would then be removed from the vessel for processing. When outside the tokamak, these plates could be cooled, cleaned, recoated, inspected, and then returned to the vessel in an automated loop. This scheme could provide nearoptimal divertor surfaces at all times, and avoid the need to stop machine operation for repair of damaged or eroded plates. We describe various possible divertor plate designs and access geometries, and discuss an initial design for a movable and removable divertor module for NSTX-U.

  12. Rapidly Moving Divertor Plates In A Tokamak

    International Nuclear Information System (INIS)

    It may be possible to replace conventional actively cooled tokamak divertor plates with a set of rapidly moving, passively cooled divertor plates on rails. These plates would absorb the plasma heat flux with their thermal inertia for ∼10-30 sec, and would then be removed from the vessel for processing. When outside the tokamak, these plates could be cooled, cleaned, recoated, inspected, and then returned to the vessel in an automated loop. This scheme could provide nearoptimal divertor surfaces at all times, and avoid the need to stop machine operation for repair of damaged or eroded plates. We describe various possible divertor plate designs and access geometries, and discuss an initial design for a movable and removable divertor module for NSTX-U.

  13. Genetics Home Reference: rapid-onset dystonia parkinsonism

    Science.gov (United States)

    Skip to main content Your Guide to Understanding Genetic Conditions Enable Javascript for addthis links to activate. ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions rapid-onset dystonia parkinsonism rapid- ...

  14. Characteristics of centrifugal rapid contactor, (3)

    International Nuclear Information System (INIS)

    Organic solvent yields the degradation product as a result of irradiation, in the extraction process of spent fuel reprocessing. The development of a centrifugal rapid contactor is required for the reduction of the solvent degradation by shortening the contact time. The effects of fine solid particles were investigated with a SGN-Robatel LX-208N contactor, following the uranium extraction and re-extraction performance tests. It was found as the experimental result that the considerable quantity of solids accumulated in the rotor of the centrifugal contactor. As for this experimental apparatus, the flow diagram for the centrifugal rapid contactor and auxiliary apparatuses is shown, which are the same system used for the uranium extraction and re-extraction tests. The schematic diagram, the typical stage construction and fluid transfer path of the LX-208 contactor are illustrated. The main specifications of the LX-208 contactor are as follows: the internal diameter of a rotating bowl 200 mm, the material SUS 316, the number of stages 8, and the total hold-up volume of the contactor 1.8 l. Most tests were carried out with aqueous feed only, because white Alundum is easily deposited in the rotor, and the particle concentration in effluent stream becomes undetectable when organic and aqueous feeds are supplied simultaneously. As the experimental results, the correlation of Alundum concentration in effluent and running time, the effect of rotor speed on effluent stream concentration, the particle size distribution curves for No. 6000 and No. 8000 white Alundum, the effect of flow rate on effluent stream concentration and the effect of flow rate on particle size distribution for both No. 6000 and No. 8000 white Alundum are presented. (Nakai, Y.)

  15. Connecting network properties of rapidly disseminating epizoonotics.

    Directory of Open Access Journals (Sweden)

    Ariel L Rivas

    Full Text Available To effectively control the geographical dissemination of infectious diseases, their properties need to be determined. To test that rapid microbial dispersal requires not only susceptible hosts but also a pre-existing, connecting network, we explored constructs meant to reveal the network properties associated with disease spread, which included the road structure.Using geo-temporal data collected from epizoonotics in which all hosts were susceptible (mammals infected by Foot-and-mouth disease virus, Uruguay, 2001; birds infected by Avian Influenza virus H5N1, Nigeria, 2006, two models were compared: 1 'connectivity', a model that integrated bio-physical concepts (the agent's transmission cycle, road topology into indicators designed to measure networks ('nodes' or infected sites with short- and long-range links, and 2 'contacts', which focused on infected individuals but did not assess connectivity.THE CONNECTIVITY MODEL SHOWED FIVE NETWORK PROPERTIES: 1 spatial aggregation of cases (disease clusters, 2 links among similar 'nodes' (assortativity, 3 simultaneous activation of similar nodes (synchronicity, 4 disease flows moving from highly to poorly connected nodes (directionality, and 5 a few nodes accounting for most cases (a "20:80" pattern. In both epizoonotics, 1 not all primary cases were connected but at least one primary case was connected, 2 highly connected, small areas (nodes accounted for most cases, 3 several classes of nodes were distinguished, and 4 the contact model, which assumed all primary cases were identical, captured half the number of cases identified by the connectivity model. When assessed together, the synchronicity and directionality properties explained when and where an infectious disease spreads.Geo-temporal constructs of Network Theory's nodes and links were retrospectively validated in rapidly disseminating infectious diseases. They distinguished classes of cases, nodes, and networks, generating information usable

  16. Diamond grooving of rapidly solidified optical aluminium

    Science.gov (United States)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  17. Safety of rapid intravenous of infusion acetaminophen.

    Science.gov (United States)

    Needleman, Steven M

    2013-07-01

    Intravenous acetaminophen, Ofirmev®, is approved for management of mild to moderate pain, management of moderate to severe pain with adjunctive opioids, and reduction of fever. The product is supplied as a 100 mL glass vial. As stated in the prescribing information, it is recommended to be infused over 15 minutes. This recommendation is related to the formulation propacetamol, the prodrug to acetaminophen, approved in Europe, which caused pain on infusion, and data from the clinical development of acetaminophen. The objective of this retrospective chart review study was to show the lack of side effects of rapidly infusing intravenous acetaminophen. Charts of American Society of Anesthesiology (ASA) Class I-III ambulatory surgical patients who received only acetaminophen in the preoperative setting were reviewed for any infusion-related side effects. Using standard binomial proportion analyses and employing SAS/JMP software, all vital signs were analyzed for statistically significant changes between pre- and postinfusion values. One hundred charts were reviewed. Only one patient had pain on infusion, which lasted 10 seconds. No reported side effects or erythema was seen at the injection site. No infusions had to be slowed or discontinued. The median infusion time was 3:41 minutes. Of the vital signs monitored, only the systolic (P < 0.0001) and diastolic (P < 0.0099) blood pressures had statistically significant changes from pre- to postinfusion; however, they were of no clinical relevance. Acetaminophen can be administered as a rapid infusion with no significant infusion-related side effects or complications. PMID:23814378

  18. Rapid toxicity screening of gasification ashes.

    Science.gov (United States)

    Zhen, Xu; Rong, Le; Ng, Wei Cheng; Ong, Cynthia; Baeg, Gyeong Hun; Zhang, Wenlin; Lee, Si Ni; Li, Sam Fong Yau; Dai, Yanjun; Tong, Yen Wah; Neoh, Koon Gee; Wang, Chi-Hwa

    2016-04-01

    The solid residues including bottom ashes and fly ashes produced by waste gasification technology could be reused as secondary raw materials. However, the applications and utilizations of these ashes are very often restricted by their toxicity. Therefore, toxicity screening of ash is the primary condition for reusing the ash. In this manuscript, we establish a standard for rapid screening of gasification ashes on the basis of in vitro and in vivo testing, and henceforth guide the proper disposal of the ashes. We used three different test models comprising human cell lines (liver and lung cells), Drosophila melanogaster and Daphnia magna to examine the toxicity of six different types of ashes. For each ash, different leachate concentrations were used to examine the toxicity, with C0 being the original extracted leachate concentration, while C/C0 being subsequent diluted concentrations. The IC50 for each leachate was also quantified for use as an index to classify toxicity levels. The results demonstrated that the toxicity evaluation of different types of ashes using different models is consistent with each other. As the different models show consistent qualitative results, we chose one or two of the models (liver cells or lung cells models) as the standard for rapid toxicity screening of gasification ashes. We may classify the gasification ashes into three categories according to the IC50, 24h value on liver cells or lung cells models, namely "toxic level I" (IC50, 24h>C/C0=0.5), "toxic level II" (C/C0=0.05types of ashes generated in gasification plants every day. Subsequently, appropriate disposal methods can be recommended for each toxicity category. PMID:26923299

  19. Coral reef evolution on rapidly subsiding margins

    Science.gov (United States)

    Webster, J.M.; Braga, J.C.; Clague, D.A.; Gallup, C.; Hein, J.R.; Potts, D.C.; Renema, W.; Riding, R.; Riker-Coleman, K.; Silver, E.; Wallace, L.M.

    2009-01-01

    A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2-6??m/ka) over the last 500??ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20??ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100-500??ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate

  20. Sensitive, Rapid Detection of Bacterial Spores

    Science.gov (United States)

    Kern, Roger G.; Venkateswaran, Kasthuri; Chen, Fei; Pickett, Molly; Matsuyama, Asahi

    2009-01-01

    A method of sensitive detection of bacterial spores within delays of no more than a few hours has been developed to provide an alternative to a prior three-day NASA standard culture-based assay. A capability for relatively rapid detection of bacterial spores would be beneficial for many endeavors, a few examples being agriculture, medicine, public health, defense against biowarfare, water supply, sanitation, hygiene, and the food-packaging and medical-equipment industries. The method involves the use of a commercial rapid microbial detection system (RMDS) that utilizes a combination of membrane filtration, adenosine triphosphate (ATP) bioluminescence chemistry, and analysis of luminescence images detected by a charge-coupled-device camera. This RMDS has been demonstrated to be highly sensitive in enumerating microbes (it can detect as little as one colony-forming unit per sample) and has been found to yield data in excellent correlation with those of culture-based methods. What makes the present method necessary is that the specific RMDS and the original protocols for its use are not designed for discriminating between bacterial spores and other microbes. In this method, a heat-shock procedure is added prior to an incubation procedure that is specified in the original RMDS protocols. In this heat-shock procedure (which was also described in a prior NASA Tech Briefs article on enumerating sporeforming bacteria), a sample is exposed to a temperature of 80 C for 15 minutes. Spores can survive the heat shock, but nonspore- forming bacteria and spore-forming bacteria that are not in spore form cannot survive. Therefore, any colonies that grow during incubation after the heat shock are deemed to have originated as spores.

  1. Rapid acoustic survey for biodiversity appraisal.

    Directory of Open Access Journals (Sweden)

    Jérôme Sueur

    Full Text Available Biodiversity assessment remains one of the most difficult challenges encountered by ecologists and conservation biologists. This task is becoming even more urgent with the current increase of habitat loss. Many methods-from rapid biodiversity assessments (RBA to all-taxa biodiversity inventories (ATBI-have been developed for decades to estimate local species richness. However, these methods are costly and invasive. Several animals-birds, mammals, amphibians, fishes and arthropods-produce sounds when moving, communicating or sensing their environment. Here we propose a new concept and method to describe biodiversity. We suggest to forego species or morphospecies identification used by ATBI and RBA respectively but rather to tackle the problem at another evolutionary unit, the community level. We also propose that a part of diversity can be estimated and compared through a rapid acoustic analysis of the sound produced by animal communities. We produced alpha and beta diversity indexes that we first tested with 540 simulated acoustic communities. The alpha index, which measures acoustic entropy, shows a logarithmic correlation with the number of species within the acoustic community. The beta index, which estimates both temporal and spectral dissimilarities, is linearly linked to the number of unshared species between acoustic communities. We then applied both indexes to two closely spaced Tanzanian dry lowland coastal forests. Indexes reveal for this small sample a lower acoustic diversity for the most disturbed forest and acoustic dissimilarities between the two forests suggest that degradation could have significantly decreased and modified community composition. Our results demonstrate for the first time that an indicator of biological diversity can be reliably obtained in a non-invasive way and with a limited sampling effort. This new approach may facilitate the appraisal of animal diversity at large spatial and temporal scales.

  2. Framework for Bus Rapid Transit Development and Deployment Planning

    OpenAIRE

    Miller, Mark A.; Yin, Yafeng; Balvanyos, Tunde; Ceder, Avishai

    2004-01-01

    This report presents the results of its investigation into deployment planning for bus rapid transit systems. In this study, we conducted a macro-scale examination of bus rapid transit systems from technical, operational, institutional, and planning perspectives. We then developed the theoretical foundation for a deployment planning framework for bus rapid transit systems that specifically takes into account the unique features of bus rapid transit that differ from other transit alternatives....

  3. Cognitive-Behavioral Therapy for Rapid Cycling Bipolar Disorder

    Science.gov (United States)

    Reilly-Harrington, Noreen A.; Knauz, Robert O.

    2005-01-01

    This article describes the application of cognitive-behavioral therapy (CBT) to the treatment of rapid cycling bipolar disorder. Between 10% and 24% of bipolar patients experience a rapid cycling course, with 4 or more mood episodes occurring per year. Characterized by nonresponse to standard mood-stabilizing medications, rapid cyclers are…

  4. Rapid E-Learning Simulation Training and User Response

    Science.gov (United States)

    Rackler, Angeline

    2011-01-01

    A new trend in e-learning development is to have subject matter experts use rapid development tools to create training simulations. This type of training is called rapid e-learning simulation training. Though companies are using rapid development tools to create training quickly and cost effectively, there is little empirical research to indicate…

  5. Economic Growth——"Sound and Rapid" Development

    Institute of Scientific and Technical Information of China (English)

    刘树成

    2008-01-01

    Sound and rapid development is an intrinsic requirement in the implementation of the "scientific outlook on development" and represents an important change in the concept of economic development. This article, reviews past achievements under the guidance of "rapid and sound" development, and brings to light the reasons why we need to pursue "sound and rapid" development and how it can be achieved.

  6. Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease

    Science.gov (United States)

    Wong, Min Ney; Murdoch, Bruce E.; Whelan, Brooke-Mai

    2012-01-01

    Background: Rapid syllable repetition tasks are commonly used in the assessment of motor speech disorders. However, little is known about the articulatory kinematics during rapid syllable repetition in individuals with Parkinson's disease (PD). Aims: To investigate and compare lingual kinematics during rapid syllable repetition in dysarthric…

  7. Rapid fabrication of custom patient biopsy guides.

    Science.gov (United States)

    Rajon, Didier A; Bova, Frank J; Chi, Yueh-Yun; Friedman, William A

    2009-01-01

    Image guided surgery is currently performed using frame-based as well as frameless approaches. In order to reduce the invasive nature of stereotactic guidance as well as to reduce the cost in both equipment and time required within the operating room we investigated the use of rapid prototyping (RP) technology. In our approach we fabricated custom patient specific face-masks and guides that can be applied to the patient during surgery. These guides provide a stereotactic reference for the accurate placement of surgical tools to a pre-planned target along a pre-planned trajectory. While the use of RP machines has previously been shown to be satisfactory for the accuracy standpoint, one of our design criteria, completing the entire built and introduction into the sterile field in less than 120 minutes, was unobtainable. Our primary problems were the fabrication time and the non-resistance of the built material to high-temperature sterilization. In the current study, we have investigated the use of subtractive rapid prototyping (SRP) machines to perform the same quality of surgical guidance while improving the fabrication time and allowing for choosing materials suitable for sterilization. Because SRP technology does not offer the same flexibility as RP in term of prototype shape and complexity, our software program was adapted to provide new guide designs suitable for SRP fabrication. The biopsy guide was subdivided for a more efficient built with the parts being uniquely assembled to form the final guide. The accuracy of the assembly was then assessed using a modified Brown-Roberts-Wells phantom base that allows measuring the position of a biopsy needle introduced into the guide and comparing it with the actual planned target. These tests showed that 1) SRP machines provide an average accuracy of 0.77 mm with a standard deviation of 0.05 mm (plus or minus one image pixel) and 2) SRP allows for fabrication and sterilization within three and a half hours after

  8. Rapid Map Updating Procedures Using Orthophotos

    Science.gov (United States)

    Alrajhi, M.

    2009-04-01

    The General Directorate of Surveying and Mapping (GDSM) of the Ministry for Municipal and Rural Affairs (MOMRA) of the Kingdom of Saudi Arabia has the mandate for large scale mapping of 220 Saudi Arabian cities. During the last 30 years all of these cities have been mapped in 3D at least once using stereo photogrammetric procedures. The output of these maps is in digital vector files with more than 300 types of features coded. Mapping at the required scales of 1:10,000 for the urban and suburban areas and at 1:1,000 for the urban areas proper has been a lengthy and costly process, which did not lend itself to regular updating procedures. For this reason the major cities, where most of the developments took place, have been newly mapped at about 10 year intervals. To record the changes of urban landscapes more rapidly orthophotomapping has recently been introduced. Rather than waiting for about 5 years for the line mapping of a large city after the inception of a mapping project, orthophotos could be produced a few months after a new aerial flight was made. While new, but slow stereomapping in 3D provides accurate results in conformity with the usual urban mapping specifications, the geocoded superposition of outdated maps with the more recent orthophotos provided a very useful monitoring of the urban changes. At the same time the use of orthophotos opens up a new possibility for urban map updating by on-screen digitizing in 2D. This can at least be done for the most relevant features, such as buildings, walls, roads and vegetation. As this is a faster method than 3D stereo plotting a lesser geometric accuracy is to be expected for the on-screen digitization. There is a need to investigate and to compare the two methods with respect to accuracy and speed of operation as a basis for a decision, whether to continue with new 3D stereomapping every 10 years or to introduce rapid map updating in 2D via on-screen digitization every 3 to 5 years. This presentation is about

  9. Multiplicity of rapidly oscillating Ap stars

    CERN Document Server

    Schoeller, M; Hubrig, S; Kurtz, D W

    2012-01-01

    Rapidly oscillating Ap (roAp) stars have rarely been found in binary or higher order multiple systems. This might have implications for their origin. We intend to study the multiplicity of this type of chemically peculiar stars, looking for visual companions in the range of angular separation between 0.05" and 8". We carried out a survey of 28 roAp stars using diffraction-limited near-infrared imaging with NAOS-CONICA at the VLT. Additionally, we observed three non-oscillating magnetic Ap stars. We detected a total of six companion candidates with low chance projection probabilities. Four of these are new detections, the other two are confirmations. An additional 39 companion candidates are very likely chance projections. We also found one binary system among the non-oscillating magnetic Ap stars. The detected companion candidates have apparent K magnitudes between 6.8 and 19.5 and angular separations ranging from 0.23" to 8.9", corresponding to linear projected separations of 30-2400AU. While our study confi...

  10. Rapid generation of fowl adenovirus 9 vectors.

    Science.gov (United States)

    Pei, Yanlong; Griffin, Bryan; de Jong, Jondavid; Krell, Peter J; Nagy, Éva

    2015-10-01

    Fowl adenoviruses (FAdV) have the largest genomes of any fully sequenced adenovirus genome, and are widely considered as excellent platforms for vaccine development and gene therapy. As such, there is a strong need for stream-lined protocols/strategies for the generation of recombinant adenovirus genomes. Current genome engineering strategies rely upon plasmid based homologous recombination in Escherichia coli BJ5183. This process is time-consuming, involves multiple cloning steps, and low efficiency recombination. This report describes a novel system for the more rapid generation of recombinant fowl adenovirus genomes using the lambda Red recombinase system in E. coli DH10B. In this strategy, PCR based amplicons with around 50 nt long homologous arms, a unique SwaI site and a chloramphenicol resistance gene fragment (CAT cassette), are introduced into the FAdV-9 genome in a highly efficient and site-specific manner. To demonstrate the efficacy of this system we generated FAdV-9 ORF2, and FAdV-9 ORF11 deleted, CAT marked and unmarked FAdV-9 infectious clones (FAdmids), and replaced either ORF2 or ORF11, with an EGFP expression cassette or replaced ORF2 with an EGFP coding sequence via the unique SwaI sites, in approximately one month. All recombinant FAdmids expressed EGFP and were fully infectious in CH-SAH cells. PMID:26238923

  11. A rapid molecular approach for chromosomal phasing.

    Directory of Open Access Journals (Sweden)

    John F Regan

    Full Text Available Determining the chromosomal phase of pairs of sequence variants - the arrangement of specific alleles as haplotypes - is a routine challenge in molecular genetics. Here we describe Drop-Phase, a molecular method for quickly ascertaining the phase of pairs of DNA sequence variants (separated by 1-200 kb without cloning or manual single-molecule dilution. In each Drop-Phase reaction, genomic DNA segments are isolated in tens of thousands of nanoliter-sized droplets together with allele-specific fluorescence probes, in a single reaction well. Physically linked alleles partition into the same droplets, revealing their chromosomal phase in the co-distribution of fluorophores across droplets. We demonstrated the accuracy of this method by phasing members of trios (revealing 100% concordance with inheritance information, and demonstrate a common clinical application by phasing CFTR alleles at genomic distances of 11-116 kb in the genomes of cystic fibrosis patients. Drop-Phase is rapid (requiring less than 4 hours, scalable (to hundreds of samples, and effective at long genomic distances (200 kb.

  12. Rapid monotectic solidification under free fall condition

    Institute of Scientific and Technical Information of China (English)

    LIU; Xiangrong; LU; Xiaoyu; WEI; Bingbo

    2004-01-01

    Fe-48.8% Sn monotectic, Fe-40% Sn hypomonotectic and Fe-58% Sn hypermonotectic alloys have been rapidly solidified during free fall processing in drop tube. For droplets of 100-1000 μm, the maximum undercooling for Fe-48.8% Sn, Fe40% Sn and Fe-58% Sn alloys is 270, 282 and 288 K respectively. For Fe-48.8% Sn monotectic alloy, a homogeneously dispersed microstructure can be obtained when the droplet diameter is small, and the Marangoni migration velocity Vm is 37 times as fast as Stokes velocity Vs when the dispersion sphere radius is 6 μm and undercooling is 30 K.For Fe-40% Sn hypomonotectic alloy, the microstructure undergoes a transition from columnar α-Fe dendrites distributed in Sn-rich matrix to α-Fe particles. The growth velocity of α-Fe dendrite changes from 0.45 to 4.65 m/s when the droplet diameter varies from 1000 to 100 μm. For Fe-58.8% Sn hypermonotectic alloy, the grain size of primary α-Fe dendrites decreases remarkably when undercooling increases.

  13. Rapid Measurement of Nanoparticle Thickness Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Katz-Boon, Hadas, E-mail: hadas.katz@monash.edu [Department of Materials Engineering, Monash University, VIC 3800 (Australia); Rossouw, Chris J. [Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia); Dwyer, Christian; Etheridge, Joanne [Department of Materials Engineering, Monash University, VIC 3800 (Australia); Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia)

    2013-01-15

    A method to measure the thickness of a single-crystal nanoparticle in the direction parallel to the incident beam from annular dark field scanning transmission electron microscope (ADF-STEM) images is reported, providing a map of thickness versus position across the nanoparticle-a 'thickness profile' image. The method is rapid and hence suitable for surveying large numbers of nanoparticles. The method measures the intensity scattered to a characterised ADF detector and compares this to the incident beam intensity, to obtain a normalized ADF image. The normalised intensity is then converted to thickness via dynamical ADF image simulations. The method is accurate within 10% and the precision is dominated primarily by 'shot noise'. Merits and limitations of this method are discussed. A method to calibrate the response function of the ADF detector without external equipment is also described, which is applicable to the entire range of gain and background settings. -- Highlights: Black-Right-Pointing-Pointer A method is developed to convert ADF-STEM images to 'thickness profile' images. Black-Right-Pointing-Pointer It is applicable in particles survey, facets determination and discrete tomography. Black-Right-Pointing-Pointer A method to calibrate the response of the ADF detector is described. Black-Right-Pointing-Pointer The response in analysed across a range of conditions. Black-Right-Pointing-Pointer Dynamical ADF image simulations are presented, demonstrating intensity vs. thickness dependence.

  14. Rapid Multiple Immunoenzyme Assay of Mycotoxins

    Directory of Open Access Journals (Sweden)

    Alexandr E. Urusov

    2015-01-01

    Full Text Available Mycotoxins are low molecular weight fungal metabolites that pose a threat as toxic contaminants of food products, thereby necessitating their effective monitoring and control. Microplate ELISA can be used for this purpose, but this method is characteristically time consuming, with a duration extending to several hours. This report proposes a variant of the ELISA method for the detection and quantification of three mycotoxins, ochratoxin A, aflatoxin B1 and zearalenone, in the kinetic regime. The main requirement for the proposed kinetic protocol was to provide a rapid method that combined sensitivity and accuracy. The use of biotin with an extended spacer together with a streptavidin–polyperoxidase conjugate provided high signal levels, despite these interactions occurring under non-equilibrium conditions. Duration of the individual mycotoxin assays was 20 min, whereas the analysis of all three mycotoxins in parallel reached a maximum duration of 25 min. Recovery of at least 95% mycotoxins in water-organic extracts was shown. The developed assays were successfully validated using poultry processing products and corn samples spiked with known quantities of mycotoxins. The detection limits for aflatoxin B1, ochratoxin A and zearalenone in these substances were 0.24, 1.2 and 3 ng/g, respectively.

  15. Final rapid reactivation project environmental assessment

    International Nuclear Information System (INIS)

    The US Department of Energy (DOE) has prepared an environmental assessment (EA) for the Rapid Reactivation Project at Sandia National Laboratories, New Mexico. The EA analyzes the potential effects of a proposal to increase production of neutron generators from the current capability of 600 units per year up to 2,000 units per year. The project would use existing buildings and infrastructure to the maximum extent possible to meet the additional production needs. The increased production levels would necessitate modifications and additions involving a total area of approximately 26,290 gross square feet at Sandia National Laboratories, New Mexico, Technical Area 1. Additional production equipment would be procured and installed. The no-action alternative would be to continue production activities at the current capability of 600 units per year. The EA analyzes effects on health, safety, and air quality, resulting from construction and operation and associated cumulative effects. A detailed description of the proposed action and its environmental consequences is presented in the EA

  16. A Rapid Process for Fabricating Gas Sensors

    Directory of Open Access Journals (Sweden)

    Chun-Ching Hsiao

    2014-07-01

    Full Text Available Zinc oxide (ZnO is a low-toxicity and environmentally-friendly material applied on devices, sensors or actuators for “green” usage. A porous ZnO film deposited by a rapid process of aerosol deposition (AD was employed as the gas-sensitive material in a CO gas sensor to reduce both manufacturing cost and time, and to further extend the AD application for a large-scale production. The relative resistance change (△R/R of the ZnO gas sensor was used for gas measurement. The fabricated ZnO gas sensors were measured with operating temperatures ranging from 110 °C to 180 °C, and CO concentrations ranging from 100 ppm to 1000 ppm. The sensitivity and the response time presented good performance at increasing operating temperatures and CO concentrations. AD was successfully for applied for making ZnO gas sensors with great potential for achieving high deposition rates at low deposition temperatures, large-scale production and low cost.

  17. RRTM: A rapid radiative transfer model

    Energy Technology Data Exchange (ETDEWEB)

    Mlawer, E.J.; Taubman, S.J.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)

    1996-04-01

    A rapid radiative transfer model (RRTM) for the calculation of longwave clear-sky fluxes and cooling rates has been developed. The model, which uses the correlated-k method, is both accurate and computationally fast. The foundation for RRTM is the line-by-line radiative transfer model (LBLRTM) from which the relevant k-distributions are obtained. LBLRTM, which has been extensively validated against spectral observations e.g., the high-resolution sounder and the Atmospheric Emitted Radiance Interferometer, is used to validate the flux and cooling rate results from RRTM. Validations of RRTM`s results have been performed for the tropical, midlatitude summer, and midlatitude winter atmospheres, as well as for the four Intercomparison of Radiation Codes in Climate Models (ICRCCM) cases from the Spectral Radiance Experiment (SPECTRE). Details of some of these validations are presented below. RRTM has the identical atmospheric input module as LBLRTM, facilitating intercomparisons with LBLRTM and application of the model at the Atmospheric Radiation Measurement Cloud and Radiation Testbed sites.

  18. Linear polarization of rapidly rotating ultracool dwarfs

    CERN Document Server

    Miles-Páez, Paulo Alberto; Pallé, Enric; Ramírez, Karla Peña

    2013-01-01

    Aims. We aim at studying the near infrared linear polarization signal of rapidly rotating ultracool dwarfs with spectral types ranging from M7 through T2 and projected rotational velocities vsini >= 30 km s^{-1}. All these dwarfs are believed to have dusty atmospheres and oblate shapes, an appropriate scenario to produce measurable linear polarization of the continuum light.\\\\ Methods. Linear polarimetric images were collected in the J-band for a sample of 18 fast-rotating ultracool dwarfs, five of which were also observed in the Z-band using the LIRIS spectrograph on the Cassegrain focus of the 4.2-m William Herschel Telescope. The measured median uncertainty in the linear polarization degree is +/-0.13% for our sample, which allowed us to detect polarization signatures above ~0.39% with a confidence of >=3\\sigma.\\\\ Results. About 40+/-15% of the sample is linearly polarized in the Z- and J-bands. All positive detections have linear polarization degrees ranging from 0.4% to 0.8% in both filters independently...

  19. Rapidly Estimating Natural Gas Compressibility Factor

    Institute of Scientific and Technical Information of China (English)

    Alireza Bahadori; Saeid Mokhatab; Brian F. Towler

    2007-01-01

    Natural gases containing sour components exhibit different gas compressibility factor (Z) behavior than do sweet gases. Therefore, a new accurate method should be developed to account for these differences. Several methods are available today for calculating the Z-factor from an equation of state. However, these equations are more complex than the foregoing correlations, involving a large number of parameters, which require more complicated and longer computations. The aim of this study is to develop a simplified calculation method for a rapid estimating Z-factor for sour natural gases containing as much as 90% total acid gas. In this article, two new correlations are first presented for calculating the pseudo-critical pressure and temperature of the gas mixture as a function of the gas specific gravity. Then, a simple correlation on the basis of the standard gas compressibility factor chart is introduced for a quick estimation of sweet gases' compressibility factor as a function of reduced pressure and temperature. Finally, a new corrective term related to the mole fractions of carbon dioxide and hydrogen sulfide is developed.

  20. Rapidly developing marketing regions : Southeast Asia

    International Nuclear Information System (INIS)

    The risks and opportunities in the rapidly developing markets in Southeast Asia, China in particular, were discussed. It was asserted that no other region in the world can match the long-term market opportunities that China and Southeast Asia promise. The forces driving the economic development in Southeast Asia were described, including the great potential the region holds for the petrochemical industry. Graphs showing total polyethylene production vs. demand for year 2005 were included as illustrative examples. By 2005, China is projected to be importing almost one-half of the products it consumes. Every country with excess capacity will supply China with polyethylene. The political uncertainties that makes doing business in the region a high risk undertaking were reviewed, along with other risks relevant to the petrochemical industry such as (1) high capital costs, (2) over-building to the point that there is more supply than demand for the product, (3) low-cost producers may drive down prices to maintain market share, and (4) the uncertain nature of projections regarding economic growth and (5) inflated estimates of demand for petrochemicals. 1 tab., 4 figs