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Sample records for active deformation front

  1. Active deformation of the northern front of the Eastern Great Caucasus

    NASA Astrophysics Data System (ADS)

    Niviere, Bertrand; Gagala, Lukasz; Callot, Jean-Paul; Regard, Vincent; Ringenbach, Jean-Claude

    2016-04-01

    The Arabia-Eurasia collision involved a mosaic of island arcs and microcontinents. Their accretion to the complex paleogeographic margin of Neotethys was marked by numerous collisional events. The Greater Caucasus constitute the northernmost tectonic element of this tectonic collage, developed as a back arc extensional zone now inverted, which relationships to the onset of Arabia-Eurasia continental collision and/or to the reorganization of the Arabia-Eurasia plate boundary at ˜5 Ma remain controversial. Structurally, the Greater Caucasus are a former continental back arc rift, now the locus of ongoing continental shortening. Modern geodetic observations suggest that in the west, the strain north of the Armenian Plateau is accommodated almost exclusively along the margins of the Greater Caucasus. This differs from regions further east where strain accommodation is distributed across both the Lesser and Greater Caucasus, and within the Greater Caucasus range, with a unique southward vergence. We question here the amount and mechanisms by which the Eastern Greater Caucasus accommodate part of the Arabia-Eurasia convergence. Morphostructural analysis of the folded late Pleistocene marine terrace along the northern slope of the Eastern Greater Caucasus evidences an on going tectonic activity in the area where GPS measurements record no motion. Most of the recent foreland deformation is accommodated by south-vergent folds and thrust, i. e. opposite to the vergence of the Caucasus frontal northern thrust. A progressive unconformity in the folded beds shows that it was already active during the late Pliocene. Cosmogenic dating of the terrace and kinematic restoration of the remnant terrace, linked to the subsurface geology allows for the estimation of a shortening rate ranging from a few mm/yr to 1 cm/yr over the last 5 Myr along the greater Caucasus northern front. Thus more than one third of the shortening between the Kura block / Lesser Caucasus domain and the Stable

  2. Offshore Deformation Front in Miaoli Area

    NASA Astrophysics Data System (ADS)

    Chiang, P.; Gwo-shyn, S.

    2015-12-01

    Taiwan is located at the junction of the Eurasian Plate and the Philippine Sea Plate. It's because arc-continent collision occurs in the western Taiwan, resulting in the orogeny has formed a fold-and-thrust belt, developing a series of thrusts aligned in north-south direction. The thrust faults, locating in the central island, are the oldest and have almost inactive. Westward to the island, the faults become younger, dipping angles are smaller, and motions were stronger. On the west side, the foot of the Taiwan Western Foothill is considered the youngest thrust faults located along west Taiwan. Scholars recognized them as so-called the deformation front, and they also believed that the deformation front is located in between the compressive terrain uplifted area and the extensional subsidence area. Therefore, this front line is on the boundary of two different tectonic zones. This study investigates the trace of the deformation front in Miaoli area. Previous studies suggested that the west side of Miaoli collision zone should be fault-bounded, and is located in the seabed. However, in the geological map, there is no geologic evidence that appears on land and so-called active faults related with this deformation front. In the near coast seafloor, according to the reflection earthquakes data from the Institute of Oceanography of NTU, we can only see the offshore strata have been uplifted, and the data also shows that seabed is only covered by thin layer of sediments. This study indicates that in offshore place within three kilometers, shallow formations show a special layer of slime which was extruded to be corrugated transversely. Accordingly, we believe that this slime layer should be pressurized and filled with muddy water. Such features should be further investigated with other geological and geophysical survey data to check if they belong to the structural product of the deformation front.

  3. Neotectonics and structure of the Himalayan deformation front in the Kashmir Himalaya, India: Implication in defining what controls a blind thrust front in an active fold-thrust belt

    NASA Astrophysics Data System (ADS)

    Gavillot, Y. G.; Meigs, A.; Yule, J. D.; Rittenour, T. M.; Malik, M. O. A.

    2014-12-01

    Active tectonics of a deformation front constrains the kinematic evolution and structural interaction between the fold-thrust belt and most-recently accreted foreland basin. In Kashmir, the Himalayan Frontal thrust (HFT) is blind, characterized by a broad fold, the Suruin-Mastargh anticline (SMA), and displays no emergent faults cutting either limb. A lack of knowledge of the rate of shortening and structural framework of the SMA hampers quantifying the earthquake potential for the deformation front. Our study utilized the geomorphic expression of dated deformed terraces on the Ujh River in Kashmir. Six terraces are recognized, and three yield OSL ages of 53 ka, 33 ka, and 0.4 ka. Vector fold restoration of long terrace profiles indicates a deformation pattern characterized by regional uplift across the anticlinal axis and back-limb, and by fold limb rotation on the forelimb. Differential uplift across the fold trace suggests localized deformation. Dip data and stratigraphic thicknesses suggest that a duplex structure is emplaced at depth along the basal décollement, folding the overlying roof thrust and Siwalik-Muree strata into a detachment-like fold. Localized faulting at the fold axis explains the asymmetrical fold geometry. Folding of the oldest dated terrace, suggest that rock uplift rates across the SMA range between 2.0-1.8 mm/yr. Assuming a 25° dipping ramp for the blind structure on the basis of dip data constraints, the shortening rate across the SMA ranges between 4.4-3.8 mm/yr since ~53 ka. Of that rate, ~1 mm/yr is likely absorbed by minor faulting in the near field of the fold axis. Given that Himalaya-India convergence is ~18.8-11 mm/yr, internal faults north of the deformation front, such as the Riasi thrust absorbs more of the Himalayan shortening than does the HFT in Kashmir. We attribute a non-emergent thrust at the deformation front to reflect deformation controlled by pre-existing basin architecture in Kashmir, in which the thick succession

  4. Mineral replacement front propagation in deformed rocks

    NASA Astrophysics Data System (ADS)

    Beaudoin, Nicolas; Koehn, Daniel; Kelka, Ulrich

    2015-04-01

    Fluid migrations are a major agent of contaminant transport leading to mineral replacement in rocks, impacting their properties as porosity, permeability, and rheology. Understanding the physical and chemical mechanisms that govern mineralogical replacement during and after deformation is required to better understand complex interplays between fluid and rocks that are involved in faulting, seismic cycle, and resource distribution in the upper crust. Dolomitization process related to hydrothermal fluid flow is one of the most studied and debated replacement processes in earth sciences. Dolomitization of limestone is of economic importance as well, as it stands as unconventional oil reservoirs and is systematically observed in Mississippian-Valley Type ore deposit. Despite recent breakthrough about dolomitization processes at large-scale, the small-scale propagation of the reaction front remains unclear. It is poorly documented in the occurrence of stylolites and fractures in the medium while pressure-solution and fracture network development are the most efficient deformation accomodation mechanism in limestone from early compaction to layer-parallel shortening. Thus, the impact of such network on geometry of replaced bodies and on replacement front propagation deserves specific attention. This contribution illustrates the role of fracture and stylolites on the propagation of a reaction front. In a 2 dimensional numerical model we simulate the dolomitization front propagation in a heterogeneous porous medium. The propagation of the reaction front is governed by the competition between advection and diffusion processes, and takes into account reaction rates, disorder in the location of the potential replacement seeds, and permeability heterogeneities. We add stylolites and fractures that can act as barriers or drains to fluid flow according to their orientation and mineralogical content, which can or cannot react with the contaminant. The patterns produced from

  5. Active learning of Pareto fronts.

    PubMed

    Campigotto, Paolo; Passerini, Andrea; Battiti, Roberto

    2014-03-01

    This paper introduces the active learning of Pareto fronts (ALP) algorithm, a novel approach to recover the Pareto front of a multiobjective optimization problem. ALP casts the identification of the Pareto front into a supervised machine learning task. This approach enables an analytical model of the Pareto front to be built. The computational effort in generating the supervised information is reduced by an active learning strategy. In particular, the model is learned from a set of informative training objective vectors. The training objective vectors are approximated Pareto-optimal vectors obtained by solving different scalarized problem instances. The experimental results show that ALP achieves an accurate Pareto front approximation with a lower computational effort than state-of-the-art estimation of distribution algorithms and widely known genetic techniques.

  6. Locating the Caledonian Deformation Front in the Western Barents Sea

    NASA Astrophysics Data System (ADS)

    Shulgin, Alexey; Aarseth, Iselin; Faleide, Jan-Inge; Mjelde, Rolf; Huismans, Ritske

    2016-04-01

    The crustal architecture of the Paleozoic sedimentary basins and the underlying basement is still not fully understood in the Western Barents Sea region. It has been proposed that the major basins have developed along the structural framework inherited from the early Devonian Caledonian orogeny. However, the location of the Caledonian suture zone and its orientation and the extent of the deformation front are still poorly constrained and are ambiguous in the Barents Sea. Two orientations of the Caledonian Deformation Front (CDF) have been proposed earlier: north-south (from the potential fields data) and southwest-northeast (from seismic data). Knowledge of the spatial extent and orientation of the CDF has a major effect on our understanding of the evolution of the Barents Sea and provides important constrains on the basin-basement interaction. In 2014 a marine seismic experiment was conducted in the Western Barents Sea. One of the goals of the experiment is to discriminate between two proposed models and to constrain the location of the Caledonian Deformation front offshore northern Norway. We present the joint interpretation of collocated newly collected wide-angle seismic data (Ocean Bottom Seismometers) and reprocessing of the reflection seismic dataset (Multi-channel seismics) collected in the mid 80's, using modern computational techniques. The two seismic methods provide best resolution at different depth ranges, and in our modeling we combine the results from the two methods to constrain the location of the CDF along transect running Northwest-Southeast across the Western Barents Sea.

  7. Controls on structural styles along the deformation front of the Subandean zone of southern Bolivia

    NASA Astrophysics Data System (ADS)

    Rocha, Emilio; Cristallini, Ernesto Osvaldo

    2015-04-01

    The Subandean zone of southern Bolivia is a typical thin-skinned fold and thrust belt with remarkable regularity in the geometry of the structures. However, when the structural geometry and evolution are analyzed in detail, it is verified that there are many deviations from such regularity. In this paper, special emphasis has been placed on analyzing those processes that could explain the along strike variations in structural styles of the deformation front. Particularly, the role that played the upper detachment level in the development of the different structural styles observed along the deformation front is analyzed herein. This analysis is focused on the development of overpressures, which may have been essential for the activation of the detachment level in the Devonian shales of the Los Monos Formation. To do this, we made a series of 1D petroleum system models at different locations along the deformation front. This analysis allowed to model primary gas generation and secondary cracking - processes that are related to overpressure occurrence, and therefore, to the efficiency of the upper detachment level. The models suggest a close relationship between thermal evolution of the foreland basin and generation of gas, with different structural styles observed at the deformation front. Thus, it was possible to divide the deformation front of the southern Subandean zone into two distinct segments. In the northern segment, where models suggest that gas generation and overpressures of the Los Monos Formation would be well developed, the existence of composite roof duplexes is verified. On the other hand, where the models suggest that generation of gas in the Los Monos Formation would be limited, the upper detachment level is not involved in the deformation, and the existence of fault bend fold structures is verified.

  8. Unsteady deformation along the southwest Spanish Pyrenean thrust front

    NASA Astrophysics Data System (ADS)

    Teletzke, A. L.; Pares, J. M.; Kodama, K. P.; Anastasio, D. J.

    2011-12-01

    A history of unsteady fault slip is recorded by magnetic reversals in a section of Oligocene continental growth strata on the forelimb of the blind thrust Santo Domingo-Tafalla anticline. Progressive tilting during deposition of the fluvial-lacustrian mollase of the Campodarbe formation is related to slip on the foreland dipping backthrust. Tilt rates calculated with 0.15-.7 Ma resolution, constrained by the magnetostratigraphy, vary from 3°/myr to 45°/myr, indicating times of near quiescence alternating with more rapid deformation over the 5 myr history recorded in the section. The new magnetostratigraphy established in this study is further west than previous studies and provides new age control for late-stage deformation of the Pyrenean thrust front. A dense array of more than 500 samples from 164 horizons over the 3,300 m of growth section was used to develop the magnetostratigraphy. A progressive 15-step thermal demagnetization (150°-690°C) was used to determine the characteristic remanent magnetization (ChRM) by principal component analysis (PCA). The ChRM is primarily carried by magnetite and hematite, and goethite is also present in the samples. PCA and calculation of virtual geomagnetic poles determined normal and reversed polarities within the section that are correlated to the geomagnetic polarity timescale. Previous work in the Campodarbe Fm ~30 km to the east by Hogan and Burbank (1996) B. Oliva-Urcia (personal comm.) tie the base of the section to C12r, and preliminary results suggest the Campodarbe Fm extends into C8. The first 1,000 m of section is pregrowth. The onset of the progressive unconformity in the section records the onset of deformation at ~30.5 Ma. Initial deformation was rapid with 25° of dip change over 0.65 myr (38°/myr). The next 0.5 myr was nearly quiescent with only 2° of dip change (4°/myr). Subsequently deformation steadily increased to 15°/my before returning to rates near 35°/Ma. Thus, this study shows the range of

  9. Reciprocating motion of active deformable particles

    NASA Astrophysics Data System (ADS)

    Tarama, M.; Ohta, T.

    2016-05-01

    Reciprocating motion of an active deformable particle in a homogeneous medium is studied theoretically. For generality, we employ a simple model derived from symmetry considerations for the center-of-mass velocity and elliptical and triangular deformations in two dimensions. We carry out, for the first time, a systematic investigation of the reciprocating motion of a self-propelled particle. It is clarified that spontaneous breaking of the front-rear asymmetry is essential for the reciprocating motion. Moreover, two routes are found for the formation of the reciprocating motion. One is a bifurcation from a motionless stationary state. The other is destabilisation of an oscillatory rectilinear motion.

  10. Upper plate deformation and seismic barrier in front of Nazca subduction zone: The Chololo Fault System and active tectonics along the Coastal Cordillera, southern Peru

    NASA Astrophysics Data System (ADS)

    Audin, Laurence; Lacan, Pierre; Tavera, Hernando; Bondoux, Francis

    2008-11-01

    The South America plate boundary is one of the most active subduction zone. The recent Mw = 8.4 Arequipa 2001 earthquake ruptured the subduction plane toward the south over 400 km and stopped abruptly on the Ilo Peninsula. In this exact region, the subduction seismic crisis induced the reactivation of continental fault systems in the coastal area. We studied the main reactivated fault system that trends perpendicular to the trench by detailed mapping of fault related-geomorphic features. Also, at a longer time scale, a recurrent Quaternary transtensive tectonic activity of the CFS is expressed by offset river gullies and alluvial fans. The presence of such extensional fault systems trending orthogonal to the trench along the Coastal Cordillera in southern Peru is interpreted to reflect a strong coupling between the two plates. In this particular case, stress transfer to the upper plate, at least along the coastal fringe, appears to have induced crustal seismic events that were initiated mainly during and after the 2001 earthquake. The seafloor roughness of the subducting plate is usually thought to be a cause of segmentation along subduction zones. However, after comparing and discussing the role of inherited structures within the upper plate to the subduction zone segmentation in southern Peru, we suggest that the continental structure itself may exert some feedback control on the segmentation of the subduction zone and thus participate to define the rupture pattern of major subduction earthquakes along the southern Peru continental margin.

  11. Wave-front correction of a femtosecond laser using a deformable mirror

    NASA Astrophysics Data System (ADS)

    Daly, Elizabeth; Dainty, Christopher; O'Connor, Gerard; Glynn, Thomas

    2005-04-01

    Typical applications of ultra-high-power femtosecond lasers include precision drilling and surface micro-machining of metals, and micro-structuring of transparent materials. However, high peak-power pulsed lasers are difficult to focus close to the diffraction limit because of aberrations that induce deviations from a perfect spatial wave-front. The sources of these aberrations include thermally induced and nonlinear optical distortions, as well as static distortions such as those introduced by gratings used in chirped-pulse amplification (CPA). A spatially clean beam is desirable to achieve the highest possible intensity on-target, and to minimize the energy deposited outside the central focus. One way to achieve this is to correct the wave-front using an adaptive optical element such as a deformable mirror, a more cost-effective solution than increasing peak intensity by providing further pulse amplification. The wave-front of the femtosecond system is measured using a Hartmann-Shack wave-front sensor, and corrected with a 37-channel deformable membrane mirror used slightly off-axis. The deformable mirror has been tested with a FISBA OPTIK μPhase HR digital interferometer, which is also used to calibrate the performance of the wave-front sensor. The influence of fluctuations of the laser on the measurement is minimised by averaging the centroid positions obtained from several consecutive frames. The distorted wave-front is compared to a reference flat wave-front which is obtained from a collimated laser diode operating at the same wavelength as the femtosecond system. The voltages on the deformable mirror actuators are then set to minimise the difference between the measured and reference wave-fronts using a simple least squares approach. Wave-front sensor and correction software is implemented in Matlab.

  12. Wave-front sensing and deformable-mirror control in strong scintillation

    PubMed

    Roggemann; Koivunen

    2000-05-01

    Recent studies of coherent wave propagation through turbulence have shown that under conditions where scintillation is significant a continuous phase function does not in general exist, owing to the presence of branch points in the complex optical field. Because of branch points and the associated branch cuts, least-squares approaches to wave-front reconstruction and deformable-mirror control can have large errors. Branch-point reconstructors are known to provide superior performance to least-squares reconstructors, but they require that branch points be explicitly detected. Detecting branch points is a significant practical impediment owing to spatial sampling and measurement noise in real wave-front sensors. Branch points are associated with real zeros in an optical field, and hence information about the phase of the field is encoded in the amplitude of the wave. We present a new wave-front-sensor processing algorithm that exploits this observation in the wave-front-reconstruction and deformable-mirror-control process. This algorithm jointly processes three intensity measurements by using light from the beacon field to develop a set of deformable-mirror actuator commands that are maximally consistent with three intensity measurements: (1) the entire wave-front-sensor image, (2) a pupil intensity image, and (3) a conventional image. Owing to the nonlinear nature of the resulting algorithm, we have used a simulation to evaluate performance. We find that in a focused laser beam projection paradigm that uses a point-source beacon, the new algorithm provides significantly improved performance over that of conventional Hartmann sensor least-squares deformable-mirror control based on centroid processing of wave-front-sensor outputs. The performance of the new algorithm approaches, the performance of an idealized branch-point reconstructor that requires pointwise phase differences for operation.

  13. Wave front adaptation using a deformable mirror for adiabatic nanofocusing along an ultrasharp gold taper.

    PubMed

    Schmidt, Slawa; Engelke, Pascal; Piglosiewicz, Björn; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Groß, Petra

    2013-11-01

    We describe and demonstrate the use of an adaptive wave front optimization scheme for enhancing the efficiency of adiabatic nanofocusing of surface plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic nanofocusing is an emerging and promising scheme for controlled focusing of far field light into nanometric volumes. It comprises three essential steps: SPP excitation by coupling far field light to an SPP waveguide, SPP propagation along the waveguide and adiabatic SPP nanofocusing towards a geometric singularity. For commonly used complex waveguide geometries, such as, e.g., conical metal tapers, a realistic modeling and efficiency optimization is challenging. Here, we use a deformable mirror to adaptively control the wave front of the incident far field light. We demonstrate an eight-fold enhancement in nanofocusing efficiency and analyze the shape of the resulting optimized wave front. The introduced wave front optimization scheme is of general interest for guiding and controlling light on the nanoscale.

  14. Fluid and Solute Fluxes from the Deformation Front to the Upper Slope at the Cascadia Margin

    NASA Astrophysics Data System (ADS)

    Berg, R. D.; Solomon, E. A.; Johnson, H. P.; Culling, D. P.; Harris, R. N.

    2014-12-01

    Fluid expulsion from accretionary convergent margins may be an important factor in global geochemical cycling and biogeochemical processes. However, the rates and distribution of fluid flow at these margins are not well known. To better understand these processes at the Cascadia margin, we collected 35 short (<1m) sediment cores and 23 Mosquito fluid flow meter measurements along a transect from the deformation front to the upper slope offshore of the Washington coast as part of a coupled heat and fluid flow survey. We identified two active seep areas, one emergent at 1990 mbsl, and one long-lived at 1050 mbsl. At both sites we observed carbonate deposits several meters thick and hundreds of meters in horizontal dimension. Thermogenic hydrocarbons measured in pore waters at the long-lived seep site indicate deeply-sourced fluids originating at >80oC, likely migrating along faults. In addition, pore water solute profiles from the emergent seep site suggest active shallow circulation in the upper sediment column, with implications for the seep biological community and fluid budget of the margin. Pore fluid advection rates along the transect are used to characterize the geographic distribution and geologic controls on active fluid pathways. Pore water solute profiles from the sediment cores are integrated with the measured fluid advection rates to calculate solute fluxes out of the margin. Our transect of fluid flow and pore water chemistry measurements from the Cascadia margin will help to better understand fluid and geochemical cycling at accretionary convergent margins.

  15. In situ stress variations at the Variscan deformation front — Results from the deep Aachen geothermal well

    NASA Astrophysics Data System (ADS)

    Trautwein-Bruns, Ute; Schulze, Katja C.; Becker, Stephan; Kukla, Peter A.; Urai, Janos L.

    2010-10-01

    In 2004 the 2544 m deep RWTH-1 well was drilled in the city centre of Aachen to supply geothermal heat for the heating and cooling of the new student service centre "SuperC" of RWTH Aachen University. Aachen is located in a complex geologic and tectonic position at the northern margin of the Variscan deformation front at the borders between the Brabant Massif, the Hohes Venn/Eifel areas and the presently active rift zone of the Lower Rhine Embayment, where existing data on in situ stress show complex changes over short distances. The borehole offers a unique opportunity to study varying stress regimes in this area of complex geodynamic evolution. This study of the in situ stresses is based on the observation of compressive borehole breakouts and drilling-induced tensile fractures in electrical and acoustic image logs. The borehole failure analysis shows that the maximum horizontal stress trends SE-NW which is in accordance with the general West European stress trend. Stress magnitudes modelled in accordance to the Mohr-Coulomb Theory of Sliding Friction indicate minimum and maximum horizontal stress gradients of 0.019 MPa/m and 0.038 MPa/m, respectively. The occurrence of drilling-induced tensile failure and the calculated in situ stress magnitudes are consistent with a model of strike-slip deformation. The observed strike-slip faulting regime supports the extension of the Brabant Shear Zone proposed by Ahorner (1975) into the Aachen city area, where it joins the major normal faulting set of the Roer Valley Graben zone. This intersection of the inherited Variscan deformation grain and the Cenozoic deformation resulting in recent strike-slip and normal faulting activity proves the tectonically different deformation responses over a short distance between the long-lived Brabant Massif and the Cenozoic Rhine Rift System.

  16. Continental deformation and the mid-lithospheric discontinuity along the Grenville Front

    NASA Astrophysics Data System (ADS)

    Abrahams, L.; Long, M. D.; Ford, H. A.; Wirth, E. A.

    2015-12-01

    The existence of a mid-lithospheric discontinuity (MLD) within the stable continental mantle lithosphere of North America has been well established, but its interpretation remains difficult. Recent work with Ps receiver functions has found evidence for anisotropic structure at MLD depths within the western portion of the Granite-Rhyolite Province, suggesting that the MLD is the result of deformation associated with the formation of the continent. The last significant deformation to occur within the province was approximately 1.3-0.9 Ga and impacted the lithosphere east of the Grenville Front. In this study we analyzed six stations east of the front using Ps receiver functions in order to characterize anisotropy associated with the MLD in the region. Transverse and radial component Ps receiver functions were calculated for six stations (ACSO, BINY, ERPA, MCWV, SSPA, TZTN) using a multi-taper correlation technique and binned as a function of back azimuth and of epicentral distance. All six stations analyzed displayed significant positive phase energy on the radial component at ~6 seconds, which was interpreted as the Moho. At four of the six stations (ACSO, MCWV, SSPA, TZTN) the Moho showed moderate to significant complexity. At stations MCWV, SSPA, TZTN, all located along the Appalachian margin, there was significant transverse component energy at crustal depths with both two- and four-lobed anisotropy patterns observed. While ACSO, BINY, and ERPA displayed evidence of isotropic and/ or anisotropic crustal structure, a coherent pattern in back azimuth could not be established. The radial component receiver functions also exhibited negative phase energy, interpreted as the MLD, between 7.5 and 12.5 seconds (or ~80 to 120 km), at five of the six stations, with the exception of BINY, where no negative phase was observed. The transverse component receiver functions at stations ACSO, ERPA, SSPA and TZTN, also displayed a two-lobed pattern in back azimuth at MLD depths

  17. Rare, large earthquakes at the laramide deformation front - Colorado (1882) and Wyoming (1984)

    USGS Publications Warehouse

    Spence, W.; Langer, C.J.; Choy, G.L.

    1996-01-01

    The largest historical earthquake known in Colorado occurred on 7 November 1882. Knowledge of its size, location, and specific tectonic environment is important for the design of critical structures in the rapidly growing region of the Southern Rocky Mountains. More than one century later, on 18 October 1984, an mb 5.3 earthquake occurred in the Laramie Mountains, Wyoming. By studying the 1984 earthquake, we are able to provide constraints on the location and size of the 1882 earthquake. Analysis of broadband seismic data shows the 1984 mainshock to have nucleated at a depth of 27.5 ?? 1.0 km and to have ruptured ???2.7 km updip, with a corresponding average displacement of about 48 cm and average stress drop of about 180 bars. This high stress drop may explain why the earthquake was felt over an area about 3.5 times that expected for a shallow earthquake of the same magnitude in this region. A microearthquake survey shows aftershocks to be just above the mainshock's rupture, mostly in a volume measuring 3 to 4 km across. Focal mechanisms for the mainshock and aftershocks have NE-SW-trending T axes, a feature shared by most earthquakes in western Colorado and by the induced Denver earthquakes of 1967. The only data for the 1882 earthquake were intensity reports from a heterogeneously distributed population. Interpretation of these reports also might be affected by ground-motion amplification from fluvial deposits and possible significant focal depth for the mainshock. The primary aftershock of the 1882 earthquake was felt most strongly in the northern Front Range, leading Kirkham and Rogers (1985) to locate the epicenters of the aftershock and mainshock there. The Front Range is a geomorphic extension of the Laramie Mountains. Both features are part of the eastern deformation front of the Laramide orogeny. Based on knowledge of regional tectonics and using intensity maps for the 1984 and the 1967 Denver earthquakes, we reinterpret prior intensity maps for the 1882

  18. Structure of the Appalachian deformation front in western Newfoundland: Implications of multichannel seismic reflection data

    SciTech Connect

    Stockmal, G.S. ); Waldron, J.W.F. )

    1990-08-01

    Petroleum-industry multichannel marine seismic data in the public domain do not support the traditional interpretation of the Acadian deformation front in the Appalachians of western Newfoundland. They show that the Late Ordovician to latest Silurian Long Point-Clam Bank succession is folded in a northwest-facing monocline, whereas the underlying Cambrian-Ordovician platform succession dips southeast. We interpret the intervening region as a structural triangle zone similar to those at the foreland edges of other thrust belts. The contact between the Long Point Groups and the underlying Humber Arm allochthon, previously interpreted as unconformable on Port au Port Peninsula, is the southeast-vergent upper detachment surface of the triangle zone. The platform succession on the peninsula is probably within the triangle zone and is therefore allochthonous; at least 30 km of Acadian (Silurian-Devonian) northwest transport is implied. The triangle zone continues to the northeast, offshore the Bay of Islands, suggesting that Grenvillian basement of the Long Range massif is also allochthonous.

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

    NASA Astrophysics Data System (ADS)

    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

  20. 3-D Inversion of MT Data for Imaging Deformation Fronts in NW Poland

    NASA Astrophysics Data System (ADS)

    Ślęzak, Katarzyna; Jóźwiak, Waldemar; Nowożyński, Krzysztof; Brasse, Heinrich

    2016-07-01

    The Pomerania region (northwest part of Poland) occupies a significant position, where the largest European tectonic boundary is situated. This is the area of the contact between the East European Craton (EEC) and the Paleozoic Platform (PP) and it is known as the Trans-European Suture Zone (TESZ). The TESZ was formed during Paleozoic time as a consequence of the collision of several crustal units and it extends from the Black Sea in the southeast to the British Isles in the northwest. It is a region of key importance for our understanding of the tectonic history of Europe. Previous magnetotelluric (MT) results, based on 2-D inverse modeling, show that the contact zone is of lithospheric discontinuity character and there are distinct differences in geoelectric structures between the Precambrian EEC, transitional zone (TESZ), and the younger PP. The presence of a significant conductor at mid and lower crustal depths was also shown. Thus, the main aim of the research presented here was to obtain detailed, 3-D images of electrical conductivity in the crust and upper mantle and its regional distribution below the TESZ in the northwest part of Poland. To accomplish this task we applied the latest 3-D inversion codes, which allowed us to get more realistic model geometries. Additionally, to confirm and complement the study, the Horizontal Magnetic Tensor (HMT) analysis was realized. This method gives us an opportunity to efficiently locate the position of well-conducting structures. As a result we obtain a clearer, three-dimensional model of conductivity distribution, where highly conductive rock complexes appear which we tentatively connected to deformation fronts.

  1. Deformation effect simulation and optimization for double front axle steering mechanism

    NASA Astrophysics Data System (ADS)

    Wu, Jungang; Zhang, Siqin; Yang, Qinglong

    2013-03-01

    This paper research on tire wear problem of heavy vehicles with Double Front Axle Steering Mechanism from the flexible effect of Steering Mechanism, and proposes a structural optimization method which use both traditional static structural theory and dynamic structure theory - Equivalent Static Load (ESL) method to optimize key parts. The good simulated and test results show this method has high engineering practice and reference value for tire wear problem of Double Front Axle Steering Mechanism design.

  2. Deformation Monitoring of AN Active Fault

    NASA Astrophysics Data System (ADS)

    Ostapchuk, A.

    2015-12-01

    The discovery of low frequency earthquakes, slow slip events and other deformation phenomena, new for geophysics, change our understanding of how the energy accumulated in the Earth's crust do release. The new geophysical data make one revise the underlying mechanism of geomechanical processes taking place in fault zones. Conditions for generating different slip modes are still unclear. The most vital question is whether a certain slip mode is intrinsic for a fault or may be controlled by external factors. This work presents the results of two and a half year deformation monitoring of a discontinuity in the zone of the Main Sayanskiy Fault. Main Sayanskiy Fault is right-lateral strike-slip fault. Observations were performed in the tunnel of Talaya seismic station (TLY), Irkutsk region, Russia. Measurements were carried out 70 m away from the entrance of the tunnel, the thickness of overlying rock was about 30 m. Inductive sensors of displacement were mounted at the both sides of a discontinuity, which recorded three components of relative fault side displacement with the accuracy of 0.2 mcm. Temperature variation inside the tunnel didn't exceed 0.5oC during the all period of observations. Important information about deformation properties of an active fault was obtained. A pronounced seasonality of deformation characteristics of discontinuity is observed in the investigated segment of rock. A great number of slow slip events with durations from several hours to several weeks were registered. Besides that alterations of fault deformation characteristics before the megathrust earthquake M9.0 Tohoku Oki 11 March 2011 and reaction to the event itself were detected. The work was supported by the Russian Science Foundation (grant no. 14-17-00719).

  3. Viscoelastic deformation near active plate boundaries

    NASA Technical Reports Server (NTRS)

    Ward, S. N.

    1986-01-01

    Model deformations near the active plate boundaries of Western North America using space-based geodetic measurements as constraints are discussed. The first six months of this project were spent gaining familarity with space-based measurements, accessing the Crustal Dynamics Data Information Computer, and building time independent deformation models. The initial goal was to see how well the simplest elastic models can reproduce very long base interferometry (VLBI) baseline data. From the Crustal Dynamics Data Information Service, a total of 18 VLBI baselines are available which have been surveyed on four or more occasions. These data were fed into weighted and unweighted inversions to obtain baseline closure rates. Four of the better quality lines are illustrated. The deformation model assumes that the observed baseline rates result from a combination of rigid plate tectonic motions plus a component resulting from elastic strain build up due to a failure of the plate boundary to slip at the full plate tectonic rate. The elastic deformation resulting from the locked plate boundary is meant to portray interseismic strain accumulation. During and shortly after a large interplate earthquake, these strains are largely released, and points near the fault which were previously retarded suddenly catch up to the positions predicted by rigid plate models. Researchers judge the quality of fit by the sum squares of weighted residuals, termed total variance. The observed baseline closures have a total variance of 99 (cm/y)squared. When the RM2 velocities are assumed to model the data, the total variance increases to 154 (cm/y)squared.

  4. Active Beam Shaping System and Method Using Sequential Deformable Mirrors

    NASA Technical Reports Server (NTRS)

    Norman, Colin A. (Inventor); Pueyo, Laurent A. (Inventor)

    2015-01-01

    An active optical beam shaping system includes a first deformable mirror arranged to at least partially intercept an entrance beam of light and to provide a first reflected beam of light, a second deformable mirror arranged to at least partially intercept the first reflected beam of light from the first deformable mirror and to provide a second reflected beam of light, and a signal processing and control system configured to communicate with the first and second deformable mirrors. The first deformable mirror, the second deformable mirror and the signal processing and control system together provide a large amplitude light modulation range to provide an actively shaped optical beam.

  5. Far-field correlation of bidirectional tracking beams due to wave-front deformation in inter-satellites optical communication links.

    PubMed

    Yu, Siyuan; Ma, Zhongtian; Ma, Jing; Wu, Feng; Tan, Liying

    2015-03-23

    In some applications of optical communication systems, such as inter-satellites optical communication, the correlation of the bidirectional tracking beams changes in far-field as a result of wave-front deformation. Far-field correlation model with wave-front deformation on tracking stability is established. Far-field correlation function and factor have been obtained. Combining with parameters of typical laser communication systems, the model is corrected. It shows that deformation pointing-tracking errors θ(A) and θ(B), far-field correlation factor δ depend on RMS of deformation error rms, which decline with a increasing rms including Tilt and Coma. The principle of adjusting far-field correlation factor with wave-front deformation to compensate deformation pointing-tracking errors has been given, through which the deformation pointing-tracking error is reduced to 18.12″ (Azimuth) and 17.65″ (Elevation). Work above possesses significant reference value on optimization design in inter-satellites optical communication.

  6. Propagation of the deformation front beyond a decollement disrupted by a step : from the Jura case to general conclusions.

    NASA Astrophysics Data System (ADS)

    Caer, Typhaine; Souloumiac, Pauline; Maillot, Bertrand; Leturmy, Pascale

    2016-04-01

    The North of the Jura fold-and-thrust-belt is an example of a thin-skin belt developed over a disrupted décollement. During Oligocene, the area of the current northern Jura undergoes the West European E-W extension that opens the Rhine and Bresse grabens, offsetting the Triassic evaporitic décollement layer. During Miocene, the alpine, roughly N-S, compressive regime folds this prefractured cover. The presence of deformation to the North of a step down in the décollement is sometimes interpreted as the proof of the activation of a deeper décollement, on the basis that outward propagation of deformation must activate shallower decollements and cannot activate deeper ones. Using the limit analysis theory, we demonstrate that for a given set of physical parameters (friction/cohesion), a lowered portion of a décollement can be reactivated depending on the height of the offset and on the topography above it. By sandbox experiment, we illustrate the general behavior of this localization along a disrupted décollement, we show that the offsets represent slowdowns in the deformation. They act as catching points that localize a ramp until the created topography is sufficient to block the ongoing deformation on this ramp allowing it propagation farther along the lowered portion of the décollement level. We use the mechanical analysis to quantify the general conditions in which an offset can block or not the propagation of deformation.

  7. Modeling technique for the Hubble Space Telescope wave-front deformation.

    PubMed

    Sasïse, M; Rousselet, K; Lazarides, E

    1995-05-01

    Images from the Hubble Space Telescope suffer from an overcorrected spherical aberration that is due to a conic-constant error in the primary mirror. Within the program known as the corrective optics space telescope axial replacement (COSTAR) simulators have been built to provide the point-spread function (PSF) of the telescope alone and of the telescope with the faint-object camera F/96. It was found that the experimental PSF's were identical to those in orbit, which was not the case when the PSF's were calculated with commonly used optical software. We explain this discrepancy and propose a modeling method that is based on the determination of the wave-front error at the exit-pupil level that gives results that are consistent with observations.

  8. Correcting Thermal Deformations in an Active Composite Reflector

    NASA Technical Reports Server (NTRS)

    Bradford, Samuel C.; Agnes, Gregory S.; Wilkie, William K.

    2011-01-01

    Large, high-precision composite reflectors for future space missions are costly to manufacture, and heavy. An active composite reflector capable of adjusting shape in situ to maintain required tolerances can be lighter and cheaper to manufacture. An active composite reflector testbed was developed that uses an array of piezoelectric composite actuators embedded in the back face sheet of a 0.8-m reflector panel. Each individually addressable actuator can be commanded from 500 to +1,500 V, and the flatness of the panel can be controlled to tolerances of 100 nm. Measuring the surface flatness at this resolution required the use of a speckle holography interferometer system in the Precision Environmental Test Enclosure (PETE) at JPL. The existing testbed combines the PETE for test environment stability, the speckle holography system for measuring out-of-plane deformations, the active panel including an array of individually addressable actuators, a FLIR thermal camera to measure thermal profiles across the reflector, and a heat source. Use of an array of flat piezoelectric actuators to correct thermal deformations is a promising new application for these actuators, as is the use of this actuator technology for surface flatness and wavefront control. An isogrid of these actuators is moving one step closer to a fully active face sheet, with the significant advantage of ease in manufacturing. No extensive rib structure or other actuation backing structure is required, as these actuators can be applied directly to an easy-to-manufacture flat surface. Any mission with a surface flatness requirement for a panel or reflector structure could adopt this actuator array concept to create lighter structures and enable improved performance on orbit. The thermal environment on orbit tends to include variations in temperature during shadowing or changes in angle. Because of this, a purely passive system is not an effective way to maintain flatness at the scale of microns over several

  9. Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado

    USGS Publications Warehouse

    Cole, James C.; Trexler, James H.; Cashman, Patricia H.; Miller, Ian M.; Shroba, Ralph R.; Cosca, Michael A.; Workman, Jeremiah B.

    2010-01-01

    This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park?Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy records the transition from Late Cretaceous marine shale to recessional shoreline sandstones to continental, fluvial, marsh, and coal mires environments, followed by orogenic sediments that span the K-T boundary. Upper Cretaceous and Paleogene strata in the Denver basin consist of two mega-fan complexes that are separated by a 9 million-year interval of erosion/non-deposition between about 63 and 54 Ma. In contrast, the marine shale unit on the western flank of the Front Range was deeply eroded over most of the area of the Colorado Headwaters Basin (approximately one km removed) prior to any orogenic sediment accumulation. New 40Ar-39Ar ages indicate the oldest sediments on the western flank of the Front Range were as young as about 61 Ma. They comprise the Windy Gap Volcanic Member of the Middle Park Formation, which consists of coarse, immature volcanic conglomerates derived from nearby alkalic-mafic volcanic edifices that were forming at about 65?61 Ma. Clasts of Proterozoic granite, pegmatite, and gneiss (eroded from the uplifted core of the Front Range) seem to arrive in the Colorado Headwaters Basin at different times in different places, but they become dominant in arkosic sandstones and conglomerates about one km above the base of the Colorado Headwaters Basin section. Paleocurrent trends suggest the southern end of the Colorado Headwaters Basin was structurally closed because all fluvial deposits show a northward component of transport. Lacustrine depositional environments are indicated by various sedimentological features in several sections within the >3 km of sediment

  10. Active Deformation of Etna Volcano Combing IFSAR and GPS data

    NASA Technical Reports Server (NTRS)

    Lundgren, Paul

    1997-01-01

    The surface deformation of an active volcano is an important indicator of its eruptive state and its hazard potential. Mount Etna volcano in Sicily is a very active volcano with well documented eruption episodes.

  11. Pockmarks, fluid flow, and sediments outboard of the deformation front at the Cascadia Subduction Zone from analysis of multi-channel seismic and multi-beam sonar data

    NASA Astrophysics Data System (ADS)

    Gibson, J. C.; Carbotte, S. M.; Han, S.; Carton, H. D.; Canales, P.; Nedimovic, M. R.

    2013-12-01

    Evidence of active fluid flow and the nature of the sediment section near the Cascadia deformation front are explored using multi-channel (MCS) seismic and multi-beam sonar data collected in summer 2012 using the R/V Marcus G. Langseth during the Juan de Fuca Ridge to Trench Survey. The MCS data were collected along two full plate transects (the 'Oregon' and 'Washington' transects) and one trench parallel line using a 6600 cubic inch source, and an 8 km streamer with 636 channels (12.5 m spacing). The MCS data pre-stack processing sequence includes geometry definition, trace editing, F-K filter, and deconvolution. Velocity analysis is performed via semblance and constant velocity stacks in order to create a velocity model of the sediments and upper oceanic crust. The traces are then stacked, and post-stack time migrated. The sonar data were collected using the R/V Langseth's Kongsberg EM122 1°x1° multi-beam sonar with 288 beams and 432 total soundings across track. Using MB-system the sonar data are cleaned, and the bathymetry data are then gridded at 35 m, while the backscatter data are gridded at 15 m. From the high-resolution mapping data 48 pockmarks varying in diameter from 50 m - 1 km are identified within 60 km outboard of the deformation front. The surface expression of these large features in an area of heavy sedimentation is likely indicative of active fluid flow. In order to gain sub-seafloor perspective on these features the MCS data are draped below the bathymetry/backscatter grids using QPS Fledermaus. From this perspective, specific locations for detailed velocity and attribute analysis of the sediment section are chosen. Sediment velocity and attribute analysis also provide insight into apparent differences in the sediment section and décollement formation along the Oregon and Washington plate transects. While both lines intersect areas of dense pockmark concentration, the area around the Oregon transect has been shown to contain a continuous

  12. Folded fluvial terraces and the deforming of a new uplifted region in the mountain front the Qilian Shan Mountain, China

    NASA Astrophysics Data System (ADS)

    Hu, X.; Pan, B.; Wang, J.; Hu, Z.

    2014-12-01

    How the Tibetan Plateau is extended is one of the key problems to understand the earth crust evolution in the frame of plate tectonics. A newly uplifting area, the Dahe region, locating between the Yumu Shan Mountain and the Qilian Shan Mountain, in the northeastern Tibetan Plateau, would supply us a fresh sight on the process that how the plateau is extended to a new region. The Dahe region was a relatively depressing or stable area before late Pleistocene, and received thick fluvial sediment derived from the Qilian Shan in the south. In late Pleistocene, the old depositing surface Sp (alluvial fan surface) was deeply cut by the Dahe River. Below the old depositing surface, four staircases of strath terraces (strath is the old fluvial deposition) are formed by the Dahe River, and each terrace surfaces are buried by aeolian loess. By the OSL dating on overlying loess on the terraces and correlating to climate records, we obtain formation ages (terrace surface abandoning time) of the four terraces (from high to low): 128.2 ±9.8 ka, 109.6±20.8 ka, 96.3 ±9.0 ka, and 15.9 ±2.5 ka. We obtain the extrapolated Sp age of 160 ±25 ka, which represents the time when the fan depositing was end and river cutting and eroding was started in the Dahe region. By the uplifted terrace staircases and warped long profiles of terraces, we can find that the region is not only experiencing regional uplifting but also folding deformation. Through analyzing the geometry of the deforming terrace surfaces, we propose that a new blind thrust fault was derived from the main decollement in the upper crust, and thus the growing fault deduced the uplift of the Dahe region and the folding near the fault tip. The growth of the Dahe region, which is sandwiched by the Yumu Shan and the Qilian Shan, both uplifted millions years ago, suggests that northeastern extending of the plateau is in the form of new fault-fold system growing in mountain front and back.

  13. Kinematics of an oblique deformation front using paleomagnetic data; the Altomira-Loranca structures (Iberian Chain, Central Spain)

    NASA Astrophysics Data System (ADS)

    Valcarcel, M.

    2013-05-01

    Manoel Valcárcel1, 5, Ruth Soto2, Elisabet Beamud3, Belén Oliva-Urcia4 and Josep Anton Muñoz5 1 IGME, Departamento de Investigación y Prospección Geocientífica. C/ La Calera, 1, 28760 Tres Cantos; m.valcarcel@igme.es 2 IGME, Unidad de Zaragoza, C/ Manuel Lasala 44, 9 B, 50006 Zaragoza, Spain 3 Lab. Paleomagnetisme (CCiT UB-CSIC). ICT "Jaume Almera", Solé i Sabarís, s/n, 08028 Barcelona, Spain. 4 IPE-CSIC, Avda. Montañana 1005, 50059 Zaragoza, Spain 5 Grup Geodinàmica i Anàlisi de Conques, Universitat de Barcelona, Zona Universitària Pedralbes, 08028 Barcelona, Spain The Altomira and Loranca structures consist of a fold-and-thrust system detached on Triassic evaporites. They are oriented N-S to NNE-SSW and NNW-SSE at its northern and southern end, respectively, forming a subtle arc, oblique with respect to the general NW-SE trend of the Iberian Chain. The aim of this work is to characterize with paleomagnetic data the kinematic evolution of the the Altomira Range, located at the southwestern deformation front of the Iberian Chain, and of the structures within its associated piggy-back basin, the Loranca basin. This approach will also give clues regarding the primary and/or secondary origin of these structures to better characterize them in further studies (3D reconstruction and restoration, fault pattern). A total of 180 samples were obtained from 19 sites in Eocene, Oligocene and Miocene rocks (including clays, fine sandstones and limestones). They were analyzed by means of stepwise thermal demagnetization and subsequent measurement of the natural remanent magnetization (NRM). Although fold tests are not statistically significant, a primary origin of the magnetization is deduced by samples showing either normal or reverse polarity after bedding correction of the calculated characteristic components. Declinations of the site mean directions appear scattered after bedding correction suggesting differential vertical-axis rotations. Sites located at the

  14. Deformation in the Bolivian Subandes: a reconstruction of geologic structures along two transects across the Andean Front in Southern Bolivia

    NASA Astrophysics Data System (ADS)

    Hadeen, Xennephone; Zeilinger, Gerold

    2016-04-01

    The Southern Bolivian Subandes is a highly tectonically active region in the Andes since deformation began approx. 10 Ma ago. The study area is located in the Southern Bolivian Subandes southwest of Santa Cruz. Observations were taken along two transects with each being around 100 km long. They stretch from the Subandes-Interandean boundary into the Chaco Plain. The northern transect extends from Abapó in the Chaco Plain and it continues west near Vallegrande and ends just west of Pucara near La Higuera. The southern transect initiates near Charagua in the Chaco Plain. Then it continues west through Villa Vaca Guzmán and ends around 25 km west of Monteagudo. Structural and stratigraphic data were collected along the two transects. The locations of major geologic structures such as thrust faults, anticlines and synclines were mapped. The map along with the data from the two cross sections was then used to generate a 3D model of the Subandean fold and thrust belt between Abapó and Monteagudo. The cross sections were than restored to quantify the amount of shortening that had occurred over the past 10 million years. The southern transect has undergone 65 km of shortening while 50 to 80 km of shortening have transpired along the less constrain northern transect. The estimated rate of deformation averages at 8 mm/yr. The timing of deformation may differ between the two transects. Deformation may have initiated earlier or undergone at a faster rate in the northern transect than in the southern transect. It is also possible that the decollement is shallower in the western portion of the northern transect. We observe that the east propagating anticlines verge to the west. This may be due to the anticlines being cut by exposed or blind thrust faults and then rotated counterclockwise. They rotate while piggybacking on younger thrust faults that developed and propagate to the east of the anticlines. We postulate deformation continues to propagate eastward into the Chaco

  15. 10Be surface exposure dating reveals strong active deformation in the central Andean backarc interior

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. The effect of deformation after backarc spreading between the rear arc and current volcanic front in Shikoku Basin obtained by seismic reflection survey

    NASA Astrophysics Data System (ADS)

    Yamashita, M.; Takahashi, N.; Nakanishi, A.; Kodaira, S.; Tamura, Y.

    2012-12-01

    Detailed crustal structure information of a back-arc basin must be obtained to elucidate the mechanism of its opening. Especially, the Shikoku Basin, which occupies the northern part of the Philippine Sea Plate between the Kyushu-Palau Ridge and the Izu-Bonin (Ogasawara) Arc, is an important area to understand the evolution of the back-arc basins as a part of the growth process of the Philippine Sea. Especially, the crustal structure oft the east side of Shikoku Basin is complicated by colliding to the Izu Peninsula Japan Agency for Marine-Earth Science and Technology has been carried out many multi-channel seismic reflection surveys since 2004 in Izu-Bonin region. Kodaira et al. (2008) reported the results of a refraction seismic survey along a north-south profile within paleoarc in the rear arc (i.e., the Nishi-shichito ridge) about 150 km west of current volcanic front. According to their results, the variation relationship of crustal thickness between the rear arc and volcanic front is suggested the evidence of rifting from current volcanic arc. There is the en-echelon arrangement is located in the eastern side of Shikoku Basin from current arc to rear arc, and it is known to activate after ceased spreading at 15 Ma (Okino et al., 1994) of Shikoku Basin by geologic sampling of Ishizuka et al. (2003). Our MCS results are also recognized the recent lateral fault zone is located in east side of Shikoku Basin. We carried out high density grid multi-channel seismic reflection (MCS) survey using tuned airgun in order to obtain the relationship between the lateral faults and en-echelon arrangement in KR08-04 cruise. We identified the deformation of sediments in Shikoku Basin after activity of Kanbun seamount at 8 Ma in MCS profile. It is estimated to activate a part of the eastern side of Shikoku Basin after construction of en-echelon arrangement and termination of Shikoku Basin spreading. Based on analyses of magnetic and gravity anomalies, Yamazaki and Yuasa (1998

  17. New design deforming controlling system of the active stressed lap

    NASA Astrophysics Data System (ADS)

    Ying, Li; Wang, Daxing

    2008-07-01

    A 450mm diameter active stressed lap has been developed in NIAOT by 2003. We design a new lap in 2007. This paper puts on emphases on introducing the new deforming control system of the lap. Aiming at the control characteristic of the lap, a new kind of digital deforming controller is designed. The controller consists of 3 parts: computer signal disposing, motor driving and force sensor signal disposing. Intelligent numeral PID method is applied in the controller instead of traditional PID. In the end, the result of new deformation are given.

  18. Experimental dynamic deformation analysis of active stressed lap.

    PubMed

    Zhao, Hongshen; Li, Xiaojin; Fan, Bin; Zeng, Zhige

    2016-02-20

    We introduce a method to measure the dynamic surface deformation of an active stressed lap for fabricating a 4  mf/1.5  mirror. Lap surface accuracy working in some typical deformation velocities is put forward. Experimental results indicate that dynamic lap surface accuracy is worse than that of a static surface, and dynamic surface accuracy gets worse if deformation velocity increases, while the difference of lap surface error RMS is less than 1 μm. An optimization of the processing strategy is feasible through changing the deformation velocity of the active stressed lap depending on the processing schedule. After optimizing the grinding and polishing strategy, efficiency is expected to have a significant increase. PMID:26906568

  19. Active compressive intraoceanic deformation: early stages of ophiolites emplacement?

    NASA Astrophysics Data System (ADS)

    Chamot-Rooke, Nicolas; Delescluse, Matthias; Montési, Laurent

    2010-05-01

    Oceanic lithosphere is strong and continental lithosphere is weak. As a result, there is relatively little deformation in the oceanic domain away from plate boundaries. However, the interior of oceanic lithosphere does deform when highly stressed. We review here places where intraoceanic compression is at work. In the more than 30 years since the first observations of active compressive intraplate deformation in the Central Indian Ocean through seismic profiling (Eittreim et al., 1972), compressive deformation has been identified in a variety of other oceanic tectonic settings: as a result of small differential motion between large plates (between North America and South America in the Central Atlantic; between Eurasia and Nubia offshore Gibraltar; between Macquarie and Australia plates in the Southern Ocean), within back-arcs (northwest Celebes Sea, Okushiri Ridge in the Japan Sea, on the eastern border of the Caroline plate), and ahead of subduction (Zenisu Ridge off Nankai Trough). Deformation appears to be more diffuse when larger plates are involved, and more localized for younger plates, perhaps in relation with the increasing rigidity of oceanic plates with age. The best example of diffuse deformation studied so far remains the Central Indian Ocean. Numerous marine data have been collected in this area, including shallow and deep seismic, heat flow measurements, multibeam bathymetry. The present-day deformation field has been modeled using GPS and earthquakes as far field and near field constraints respectively. Reactivation of the oceanic fabric (including for portions of the Indo-Australian plate which are now in subduction as evidenced by the September 2009 Padang earthquake), selective fault abandonment (Delescluse et al., 2008) and serpentinization (Delescluse and Chamot-Rooke, 2008) are some of the important processes that shape the present-day pattern of deformation. These rare intraplate deformation areas constitute excellent natural laboratories to

  20. Deformation invariant bounding spheres for dynamic active constraints in surgery.

    PubMed

    Bowyer, Stuart A; Rodriguez Y Baena, Ferdinando

    2014-04-01

    Active constraints are collaborative robot control strategies, which can be used to guide a surgeon or protect delicate tissue structures during robot-assisted surgery. Tissue structures of interest often move and deform throughout a surgical intervention, and therefore, dynamic active constraints, which adapt and conform to these changes, are required. A fundamental element of an active constraint controller is the computation of the geometric relationship between the constraint geometry and the surgical instrument. For a static active constraint, there are a variety of computationally efficient methods for computing this relative configuration; however, for a dynamic active constraint, it becomes significantly more challenging. Deformation invariant bounding spheres are a novel bounding volume formulation, which can be used within a hierarchy to allow efficient proximity queries within dynamic active constraints. These bounding spheres are constructed in such a way that as the surface deforms, they do not require time-consuming rebuilds or updates, rather they are implicitly updated and continue to represent the underlying geometry as it changes. Experimental results show that performing proximity queries with deformation invariant bounding sphere hierarchies is faster than common methods from the literature when the deformation rate is within the range expected from conventional imaging systems. PMID:24622983

  1. Front Range Infrastructure Resources Project: water-resources activities

    USGS Publications Warehouse

    Robson, Stanley G.; Heiny, Janet S.

    1998-01-01

    Infrastructure, such as roads, buildings, airports, and dams, is built and maintained by use of large quantities of natural resources such as aggregate (sand and gravel), energy, and water. As urban area expand, local sources of these resource are becoming inaccessible (gravel cannot be mined from under a subdivision, for example), or the cost of recovery of the resource becomes prohibitive (oil and gas drilling in urban areas is costly), or the resources may become unfit for some use (pollution of ground water may preclude its use as a water supply). Governmental land-use decision and environmental mandates can further preclude development of natural resources. If infrastructure resources are to remain economically available. current resource information must be available for use in well-reasoned decisions bout future land use. Ground water is an infrastructure resource that is present in shallow aquifers and deeper bedrock aquifers that underlie much of the 2,450-square-mile demonstration area of the Colorado Front Range Infrastructure Resources Project. In 1996, mapping of the area's ground-water resources was undertaken as a U.S. Geological Survey project in cooperation with the Colorado Department of Natural Resources, Division of Water Resources, and the Colorado Water Conservation Board.

  2. Active Uplift At The Taiwan Belt Front Revealed By River Profiles:the Hsiaomei Anticline Area

    NASA Astrophysics Data System (ADS)

    Chen, R.-F.; Angelier, J.; Hu, J.-C.; Deffontaines, B.; Tsai, H.

    A river profile may reveal tectonic deformation through comparison with a smoothed theoretical function based on simple assumptions, provided that its relationships with the erosion-accumulation phenomena have been deciphered. The Taiwan orogeny re- sults from the collision between the Luzon volcanic arc of the Philippine Sea plate and the Chinese continental margin of the Eurasian plate. As an active collision zone between the Luzon arc and the China continental margin, the Taiwan mountain belt, particularly its south-central part, is undergoing strong crustal shortening and rapid uplift. In the central part of the island, rock uplift rates are matched by erosion rates calculated from sediment yields and exhumation rates. In the foothills of southwestern Taiwan we focus on the longitudinal profiles of twelve rivers near Chiayi area. Based on the fit with mathematical functions, we characterize a significant positive anomaly in terms of shape, amplitude and location. River data from 1/5,000 topographic maps were used to define a set of parameters related to the classical exponential equation of the longitudinal profiles. We obtained an accepted fit for a set of 5-7 parameters of the polynomial exponent, that is, a degree 4-6. The anomaly is spatially consistent and does not show correlation with variations in erosional-depositional phenomena, including variations in lithology of the rock formations. The anomaly thus reflects tectonic uplift, in good agreement with other sources of information, including the GPS data that indicate active E-W shortening of about 1 cm/yr in this area. The posi- tive anomaly detected in ten river profiles diminishes and vanishes in the northernmost and southernmost river profiles. It reflects continuing folding and uplift within an ellip- tic area elongated N-S, which corresponds to the present-day growth of the Hsiaomei anticline at the front of Taiwan belt.

  3. Visualisation of the wave-front deformations caused by a phase object by the method of successive double lateral shear interferometry

    SciTech Connect

    Lyalikov, A M

    2005-03-31

    The method of moire visualisation of the wave-front deformations of a light beam propagated through a phase object is proposed. The method is based on the recording of double shear interferograms and makes it possible to obtain real-time moire pictures of the phase object with doubled sensitivity, in which the behaviour of fringes is similar to that in usual double-beam, reference-wave interferometry. The method was tested by studying the regions of thermal treatment of a polymethyl methacrylate plate. (laser applications and other topics in quantum electronics)

  4. The Impact of Oil and Natural Gas Activity on Ozone Formation in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hornbrook, R. S.; Apel, E. C.; Hills, A. J.; Blake, D. R.; Blake, N. J.; Schroeder, J.; Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Mauldin, L.; Cantrell, C. A.; Hall, S. R.; Ullmann, K.; Weinheimer, A. J.; Montzka, D.; Orlando, J. J.; Tyndall, G. S.; Campos, T. L.; Stell, M. H.; Heikes, B.; Treadaway, V.; O'Sullivan, D. W.; Huey, L. G.; Tanner, D.; Cohen, R. C.; Flocke, F. M.; Pfister, G.; Knote, C. J.; Emmons, L. K.

    2014-12-01

    The 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPE) was a ground-based and airborne field study designed to characterize and understand air quality in the Colorado Front Range, where National Ambient Air Quality Standards (NAAQS) ozone levels are frequently exceeded during summertime. A primary goal of the study was to determine the factors controlling surface ozone in the Front Range. As part of the project, measurements of many trace gases were observed on board the NSF/NCAR C-130 by a suite of instrumentation, including the NCAR Trace Organic Gas Analyzer (TOGA), which made measurements of a set of volatile organic compounds (VOCs). VOCs are crucial for characterizing emissions and photochemical processing in the Front Range, as well as the air transported into the region. During recent years, oil and natural gas (O&NG) activity in the Front Range has been growing rapidly. Ratios of observed aromatic hydrocarbons, butanes and pentanes demonstrate distinct fingerprinting that can be used to distinguish both between different types of O&NG activities and between O&NG extraction regions in the FRAPPE study region and beyond. Using the observed hydrocarbon data along with other trace gas observations, we will compare contributions of O&NG emissions to OH reactivities in different regions in the Front Range, and present box model results demonstrating the impact of O&NG activities on ozone formation.

  5. The Impact of Oil and Natural Gas Activity on Ozone Formation in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hornbrook, R. S.; Apel, E. C.; Hills, A. J.; Blake, D. R.; Blake, N. J.; Schroeder, J.; Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Mauldin, L.; Cantrell, C. A.; Hall, S. R.; Ullmann, K.; Weinheimer, A. J.; Montzka, D.; Orlando, J. J.; Tyndall, G. S.; Campos, T. L.; Stell, M. H.; Heikes, B.; Treadaway, V.; O'Sullivan, D. W.; Huey, L. G.; Tanner, D.; Cohen, R. C.; Flocke, F. M.; Pfister, G.; Knote, C. J.; Emmons, L. K.

    2015-12-01

    The 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPE) was a ground-based and airborne field study designed to characterize and understand air quality in the Colorado Front Range, where National Ambient Air Quality Standards (NAAQS) ozone levels are frequently exceeded during summertime. A primary goal of the study was to determine the factors controlling surface ozone in the Front Range. As part of the project, measurements of many trace gases were observed on board the NSF/NCAR C-130 by a suite of instrumentation, including the NCAR Trace Organic Gas Analyzer (TOGA), which made measurements of a set of volatile organic compounds (VOCs). VOCs are crucial for characterizing emissions and photochemical processing in the Front Range, as well as the air transported into the region. During recent years, oil and natural gas (O&NG) activity in the Front Range has been growing rapidly. Ratios of observed aromatic hydrocarbons, butanes and pentanes demonstrate distinct fingerprinting that can be used to distinguish both between different types of O&NG activities and between O&NG extraction regions in the FRAPPE study region and beyond. Using the observed hydrocarbon data along with other trace gas observations, we will compare contributions of O&NG emissions to OH reactivities in different regions in the Front Range, and present box model results demonstrating the impact of O&NG activities on ozone formation.

  6. Monocytic Cells Become Less Compressible but More Deformable upon Activation

    PubMed Central

    Ravetto, Agnese; Wyss, Hans M.; Anderson, Patrick D.; den Toonder, Jaap M. J.; Bouten, Carlijn V. C.

    2014-01-01

    Aims Monocytes play a significant role in the development of atherosclerosis. During the process of inflammation, circulating monocytes become activated in the blood stream. The consequent interactions of the activated monocytes with the blood flow and endothelial cells result in reorganization of cytoskeletal proteins, in particular of the microfilament structure, and concomitant changes in cell shape and mechanical behavior. Here we investigate the full elastic behavior of activated monocytes in relation to their cytoskeletal structure to obtain a better understanding of cell behavior during the progression of inflammatory diseases such as atherosclerosis. Methods and Results The recently developed Capillary Micromechanics technique, based on exposing a cell to a pressure difference in a tapered glass microcapillary, was used to measure the deformation of activated and non-activated monocytic cells. Monitoring the elastic response of individual cells up to large deformations allowed us to obtain both the compressive and the shear modulus of a cell from a single experiment. Activation by inflammatory chemokines affected the cytoskeletal organization and increased the elastic compressive modulus of monocytes with 73–340%, while their resistance to shape deformation decreased, as indicated by a 25–88% drop in the cell’s shear modulus. This decrease in deformability is particularly pronounced at high strains, such as those that occur during diapedesis through the vascular wall. Conclusion Overall, monocytic cells become less compressible but more deformable upon activation. This change in mechanical response under different modes of deformation could be important in understanding the interplay between the mechanics and function of these cells. In addition, our data are of direct relevance for computational modeling and analysis of the distinct monocytic behavior in the circulation and the extravascular space. Lastly, an understanding of the changes of monocyte

  7. Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

    NASA Astrophysics Data System (ADS)

    Curtarelli, M. P.; Alcântara, E. H.; Rennó, C. D.; Stech, J. L.

    2014-08-01

    We investigated the influence of wintertime cold front activity on the physical processes within a large tropical reservoir located in Brazil. The period chosen for this study consisted of 49 days between 28 April 2010 and 15 July 2010. This period was defined based on information from the Brazilian Center for Weather Forecasting and Climate Studies (CPTEC), data collected in situ and the interpretation of remotely sensed images. To better understand the governing processes that drive changes in the heat balance, differential cooling and mixing dynamics, a simulation was performed that utilized a three-dimensional hydrodynamic model enforced with in situ and remote sensing data. The results showed that during a cold front passage over the reservoir, the sensible and latent heat fluxes were enhanced by approximately 77 and 16%, respectively. The reservoir's daily averaged heat loss was up to 167% higher on the days with cold front activity than on the days without activity. The cold front passage also intensified the differential cooling process; in some cases the difference between the water temperature of the littoral and pelagic zones reached up to 8 °C. The occurrence of cold front passages impacted the diurnal mixed layer (DML), by increasing the turbulent energy input (∼54%) and the DML depth (∼41%). Our results indicate that the cold front events are one of the main meteorological disturbances driving the physical processes within hydroelectric reservoirs located in tropical South America during the wintertime. Hence, cold front activity over these aquatic systems has several implications for water quality and reservoir management in Brazil.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  9. Exhumed analogues of seismically active carbonate-bearing thrusts: fault architecture and deformation mechanisms

    NASA Astrophysics Data System (ADS)

    Tesei, T.; Collettini, C.; Viti, C.; Barchi, M. R.

    2012-12-01

    In May 2012 a M = 5.9 earthquake followed by a long aftershock sequence struck the Northern Italy. The sequence occurred at 4-10 km depth within the active front of Northern Apennines Prism and the major events nucleate within, or propagate through, a thick sequence of carbonates. In an inner sector of the Northern Apennines, ancient carbonate-bearing thrusts exposed at the surface, represent exhumed analogues of structures generating seismicity in the active front. Here we document fault architecture and deformation mechanisms of three regional carbonate bearing thrusts with displacement of several kilometers and exhumation in the range of 1-4 km. Fault zone structure and deformation mechanisms are controlled by the lithology of the faulted rocks. In layered limestones and marly-limestones the fault zone is up to 200 m thick and is characterized by intense pressure solution. In massive limestones the deformation generally occurs along thin and sharp slip planes that are in contact with fault portions affected by either cataclasis or pressure solution. SEM and TEM observations show that pressure solution surfaces, made of smectite lamellae, with time tend to form an interconnected network affected by frictional sliding. Sharp slipping planes along massive limestones show localization along Y shear planes that separate an extremely comminuted cataclasites from an almost undeformed protolith. The comparison of the three shear zones depicts a fault zone structure extremely heterogeneous as the result of protolith lithology, geometrical complexities and the presence of inherited structures. We observe the competition between brittle (cataclasis, distributed frictional sliding along phyllosilicates and extremely localized slip within carbonates) and pressure solution processes, that suggest a multi-mode of slip behaviour. Extreme localization along carbonate-bearing Y shear planes is our favorite fault zone feature representing past seismic ruptures along the studied

  10. Front motion and localized states in an asymmetric bistable activator-inhibitor system with saturation

    NASA Astrophysics Data System (ADS)

    Yochelis, Arik; Garfinkel, Alan

    2008-03-01

    We study the spatiotemporal properties of coherent states (peaks, holes, and fronts) in a bistable activator-inhibitor system that exhibits biochemical saturated autocatalysis, and in which fronts do not preserve spatial parity symmetry. Using the Gierer-Meinhardt prototype model, we find the conditions in which two distinct pinning regions are formed. The first pinning type is known in the context of variational systems while the second is structurally different due to the presence of a heteroclinic bifurcation between two uniform states. The bifurcation also separates the parameter regions of counterpropagating fronts, leading in turn to the growth or contraction of activator domains. These phenomena expand the range of pattern formation theory and its biomedical applications: activator domain retraction suggests potential therapeutic strategies for patterned pathologies, such as cardiovascular calcification.

  11. Low-frequency wave activity related to dipolarization fronts detected by MMS in the magnetotail

    NASA Astrophysics Data System (ADS)

    Le Contel, O.; Retino, A.; Breuillard, H.; Mirioni, L.; Roux, A.; Chust, T.; Chasapis, A.; Lavraud, B.; Lindqvist, P. A.; Khotyaintsev, Y. V.; Vaivads, A.; Fu, H.; Marklund, G. T.; Nakamura, R.; Burch, J. L.; Torbert, R. B.; Moore, T. E.; Ergun, R.; Goodrich, K.; Needell, J.; Chutter, M.; Rau, D.; Dors, I.; Russell, C. T.; Magnes, W.; Strangeway, R. J.; Le, G.; Bromund, K. R.; Plaschke, F.; Fischer, D.; Leinweber, H. K.; Anderson, B. J.; Argall, M. R.; Slavin, J. A.; Kepko, L.; Baumjohann, W.; Pollock, C. J.; Mauk, B.; Fuselier, S. A.

    2015-12-01

    Dipolarization fronts are often associated to reconnection jets in the magnetotail current sheet and are sites of important energy dissipation and particle energization. Since the launch on March 12th and until the 9th of July 2015, the MMS constellation has been moving from dawn to dusk in a string of pearls formation. Although particle instruments were rarely operating and only FIELDS instrument suite was often gathering data, the MMS spacecraft have detected numerous dipolarization fronts, in particular on May 15th. Since 9th of July, the MMS evolved into a tetrahedral configuration with an average inter-satellite distance of 160 km and was still able to detect dipolarization fronts in the dusk magnetotail. As the Larmor radius of thermal protons is about 500 km in this region and dipolarization fronts have a typical thickness of the order of the Larmor radius, such a separation allows us to investigate in detail the microphysics of dipolarization fronts. In this study, we focus in particular on low-frequency electromagnetic wave activity related to the fronts and discuss possible mechanisms of particle heating and acceleration both at large scales (string of pearls configuration) and at kinetic scales (tetrahedral configuration).

  12. Dynamics of a deformable active particle under shear flow.

    PubMed

    Tarama, Mitsusuke; Menzel, Andreas M; ten Hagen, Borge; Wittkowski, Raphael; Ohta, Takao; Löwen, Hartmut

    2013-09-14

    The motion of a deformable active particle in linear shear flow is explored theoretically. Based on symmetry considerations, we propose coupled nonlinear dynamical equations for the particle position, velocity, deformation, and rotation. In our model, both, passive rotations induced by the shear flow as well as active spinning motions, are taken into account. Our equations reduce to known models in the two limits of vanishing shear flow and vanishing particle deformability. For varied shear rate and particle propulsion speed, we solve the equations numerically in two spatial dimensions and obtain a manifold of different dynamical modes including active straight motion, periodic motions, motions on undulated cycloids, winding motions, as well as quasi-periodic and chaotic motions induced at high shear rates. The types of motion are distinguished by different characteristics in the real-space trajectories and in the dynamical behavior of the particle orientation and its deformation. Our predictions can be verified in experiments on self-propelled droplets exposed to a linear shear flow.

  13. New constraints on the active tectonic deformation of the Aegean

    USGS Publications Warehouse

    Nyst, M.; Thatcher, W.

    2004-01-01

    Site velocities from six separate Global Positioning System (GPS) networks comprising 374 stations have been referred to a single common Eurasia-fixed reference frame to map the velocity distribution over the entire Aegean. We use the GPS velocity field to identify deforming regions, rigid elements, and potential microplate boundaries, and build upon previous work by others to initially specify rigid elements in central Greece, the South Aegean, Anatolia, and the Sea of Marmara. We apply an iterative approach, tentatively defining microplate boundaries, determining best fit rigid rotations, examining misfit patterns, and revising the boundaries to achieve a better match between model and data. Short-term seismic cycle effects are minor contaminants of the data that we remove when necessary to isolate the long-term kinematics. We find that present day Aegean deformation is due to the relative motions of four microplates and straining in several isolated zones internal to them. The RMS misfit of model to data is about 2-sigma, very good when compared to the typical match between coseismic fault models and GPS data. The simplicity of the microplate description of the deformation and its good fit to the GPS data are surprising and were not anticipated by previous work, which had suggested either many rigid elements or broad deforming zones that comprise much of the Aegean region. The isolated deforming zones are also unexpected and cannot be explained by the kinematics of the microplate motions. Strain rates within internally deforming zones are extensional and range from 30 to 50 nanostrain/year (nstrain/year, 10-9/year), 1 to 2 orders of magnitude lower than rates observed across the major microplate boundaries. Lower strain rates may exist elsewhere withi the microplates but are only resolved in Anatolia, where extension of 13 ?? 4 nstrain/ year is required by the data. Our results suggest that despite the detailed complexity of active continental deformation

  14. Geomorphic Evidence for the Deformation Front Propagation of the Malargüe Fold-and-Thrust Belt, Neuquén Andes (Argentina)

    NASA Astrophysics Data System (ADS)

    Messager, G.; Nivihre, B.; Regard, V.; Xavier, J.; Hervouet, Y.; Dhont, D.; Bonnel, C.

    2010-12-01

    Since 26 Ma, convergence between the Nazca and South American plates induces an outward propagation of the deformation front in the eastern Andean foothill, leading to the widening and thickening of the orogenesis. Nevertheless, both the mechanisms and timing of the building of the fold-and-thrust belt are poorly documented during the Plio-Quaternary due mainly to the lack of field observations. As a consequence, compression has not been observed after 5 Ma and the current stress regime is still a matter of debate. We focus our study on the Mesón and Sosneado thrusts which constitutes the thin-skinned termination of the Malargüe fold-and-thrust belt in the northern Neuquén Basin in Argentina. We analyze the remnant terraces and alluvial deposits of the Río Atuel in correlation with its current morphology. Through the integration of new cosmogenic radionuclide dating (10Be, 26Al), we present a new map of the Quaternary deposits at the toe of the Principal Cordillera that we correlate to the Pleistocene glaciations between 1 and 0.1 Ma. Tilting and folding of these deposits show that the deformation front propagated outward from the Mesón thrust in the Early Pleistocene, to the Sosneado thrust in the Middle-Late Pleistocene. Our results show that uplift velocity associated to the Sosneado thrust, ranges between 0.39±0.03 and 1.19±0.81 mm/a during the Middle-Late Pleistocene. Morphodynamic and morphosedimentary responses of the Río Atuel to the bedrock uplift produces the aggradation and storage of sediments upstream of the uplifted area. This is accompanied by the development of thick alluvial fan aprons at the catchment outlet. The process therefore disturbs the mass transfer by fluvial erosion from the orogenesis to the foreland, inducing a perturbation of the longitudinal profiles of the river and its terraces. Our observations mostly reveal that the propagation of the deformation front can be identified at the regional scale and that the stress regime in

  15. Crustal deformation and volcanism at active plate boundaries

    NASA Astrophysics Data System (ADS)

    Geirsson, Halldor

    Most of Earth's volcanoes are located near active tectonic plate boundaries, where the tectonic plates move relative to each other resulting in deformation. Likewise, subsurface magma movement and pressure changes in magmatic systems can cause measurable deformation of the Earth's surface. The study of the shape of Earth and therefore studies of surface deformation is called geodesy. Modern geodetic techniques allow precise measurements (˜1 mm accuracy) of deformation of tectonic and magmatic systems. Because of the spatial correlation between tectonic boundaries and volcanism, the tectonic and volcanic deformation signals can become intertwined. Thus it is often important to study both tectonic and volcanic deformation processes simultaneously, when one is trying to study one of the systems individually. In this thesis, I present research on crustal deformation and magmatic processes at active plate boundaries. The study areas cover divergent and transform plate boundaries in south Iceland and convergent and transform plate boundaries in Central America, specifically Nicaragua and El Salvador. The study is composed of four main chapters: two of the chapters focus on the magma plumbing system of Hekla volcano, Iceland and the plate boundary in south Iceland; one chapter focuses on shallow controls of explosive volcanism at Telica volcano, Nicaragua; and the fourth chapter focuses on co- and post-seismic deformation from a Mw = 7.3 earthquake which occurred offshore El Salvador in 2012. Hekla volcano is located at the intersection of a transform zone and a rift zone in Iceland and thus is affected by a combination of shear and extensional strains, in addition to co-seismic and co-rifting deformation. The inter-eruptive deformation signal from Hekla is subtle, as observed by a decade (2000-2010) of GPS data in south Iceland. A simultaneous inversion of this data for parameters describing the geometry and source characteristics of the magma chamber at Hekla, and

  16. Temporal evolution of continental lithospheric strength in actively deforming regions

    USGS Publications Warehouse

    Thatcher, W.; Pollitz, F.F.

    2008-01-01

    It has been agreed for nearly a century that a strong, load-bearing outer layer of earth is required to support mountain ranges, transmit stresses to deform active regions and store elastic strain to generate earthquakes. However the dept and extent of this strong layer remain controversial. Here we use a variety of observations to infer the distribution of lithospheric strength in the active western United States from seismic to steady-state time scales. We use evidence from post-seismic transient and earthquake cycle deformation reservoir loading glacio-isostatic adjustment, and lithosphere isostatic adjustment to large surface and subsurface loads. The nearly perfectly elastic behavior of Earth's crust and mantle at the time scale of seismic wave propagation evolves to that of a strong, elastic crust and weak, ductile upper mantle lithosphere at both earthquake cycle (EC, ???10?? to 103 yr) and glacio-isostatic adjustment (GIA, ???103 to 104 yr) time scales. Topography and gravity field correlations indicate that lithosphere isostatic adjustment (LIA) on ???106-107 yr time scales occurs with most lithospheric stress supported by an upper crust overlying a much weaker ductile subtrate. These comparisons suggest that the upper mantle lithosphere is weaker than the crust at all time scales longer than seismic. In contrast, the lower crust has a chameleon-like behavior, strong at EC and GIA time scales and weak for LIA and steady-state deformation processes. The lower crust might even take on a third identity in regions of rapid crustal extension or continental collision, where anomalously high temperatures may lead to large-scale ductile flow in a lower crustal layer that is locally weaker than the upper mantle. Modeling of lithospheric processes in active regions thus cannot use a one-size-fits-all prescription of rheological layering (relation between applied stress and deformation as a function of depth) but must be tailored to the time scale and tectonic

  17. Evolution of Deformation Studies on Active Hawaiian Volcanoes

    USGS Publications Warehouse

    Decker, Robert; Okamura, Arnold; Miklius, Asta; Poland, Michael

    2008-01-01

    Everything responds to pressure, even rocks. Deformation studies involve measuring and interpreting the changes in elevations and horizontal positions of the land surface or sea floor. These studies are variously referred to as geodetic changes or ground-surface deformations and are sometimes indexed under the general heading of geodesy. Deformation studies have been particularly useful on active volcanoes and in active tectonic areas. A great amount of time and energy has been spent on measuring geodetic changes on Kilauea and Mauna Loa Volcanoes in Hawai`i. These changes include the build-up of the surface by the piling up and ponding of lava flows, the changes in the surface caused by erosion, and the uplift, subsidence, and horizontal displacements of the surface caused by internal processes acting beneath the surface. It is these latter changes that are the principal concern of this review. A complete and objective review of deformation studies on active Hawaiian volcanoes would take many volumes. Instead, we attempt to follow the evolution of the most significant observations and interpretations in a roughly chronological way. It is correct to say that this is a subjective review. We have spent years measuring and recording deformation changes on these great volcanoes and more years trying to understand what makes these changes occur. We attempt to make this a balanced as well as a subjective review; the references are also selective rather than exhaustive. Geodetic changes caused by internal geologic processes vary in magnitude from the nearly infinitesimal - one micron or less, to the very large - hundreds of meters. Their apparent causes also are varied and include changes in material properties and composition, atmospheric pressure, tidal stress, thermal stress, subsurface-fluid pressure (including magma pressure, magma intrusion, or magma removal), gravity, and tectonic stress. Deformation is measured in units of strain or displacement. For example, tilt

  18. Active faulting south of the Himalayan Front: Establishing a new plate boundary

    NASA Astrophysics Data System (ADS)

    Yeats, Robert S.; Thakur, V. C.

    2008-06-01

    New tectonic uplifts south of the Salt Range Thrust and Himalayan Front Thrust (HFT) represent an outward step of the plate boundary from the principal tectonic displacement zone into the Indo-Gangetic Plain. In Pakistan, the Lilla Anticline deforms fine-grained overbank deposits of the Jhelum River floodplain 15 km south of the Salt Range. The anticline is overpressured in Eocambrian non-marine strata. In northwest India south of Dehra Dun, the Piedmont Fault (PF) lies 15 km south of the HFT. Coalescing fans derived from the Himalaya form a piedmont (Old Piedmont Zone) 15-20 km wide east of the Yamuna River. This zone is uplifted as much as 15-20 m near the PF, and bedding is tilted 5-7° northeast. Holocene thermoluminescence-optically-stimulated luminescence dates for sediments in the Old Piedmont Zone suggest that the uplift rate might be as high as several mm/a. The Old Piedmont Zone is traced northwest 200 km and southeast another 200 km to the Nepal border. These structures, analogous to protothrusts in subduction zones, indicate that the Himalayan plate boundary is not a single structure but a series of structures across strike, including reactivated parts of the Main Boundary Thrust north of the range front, the HFT sensu stricto, and stepout structures on the Indo-Gangetic Plain. Displacement rates on all these structures must be added to determine the local India-Himalaya convergence rate.

  19. Batholith Construction In Actively Deforming Crust, Coast Mountains Batholith, British Columbia

    NASA Astrophysics Data System (ADS)

    Rusmore, M. E.; Woodsworth, G. J.; Gehrels, G. E.

    2011-12-01

    Stikinia east of the YTT. Western Stikinia has NE-directed thrust faults, dextral faults and a >100 km long dextral reverse fault. Metamorphism locally produced amphibolite gneiss and NW-trending folds. This phase of transpression ended ~ca 74 Ma, marking the end of orogen-wide deformation. Subsequent deformation and magmatism are restricted to western Stikinia, coincident with the magmatic front. Between 69 and 55 Ma, N-directed shortening and exhumation of gneiss took place in restraining bend on a dextral shear zone. From ~65-53 Ma, the Coast shear zone was the locus of magmatism and reverse slip. Overall, the history of this part of the batholith shows: 1) the batholith formed in actively deforming and thickening crust within a contractional to transpressive setting. 2) Deformation and magmatism are widespread ~100-75 Ma, becoming more focused from 70-55 Ma. Crustal thickening was broadly coeval with magmatic fluxes at 120-88 and 65-55 Ma. 3) major crustal extension (55-50 Ma) and voluminous 52-48 Ma plutons present farther north are absent, suggesting a link between this magmatism and crustal extension.

  20. Estimation of the front-to-total activity ratio for wire screens using CFD simulation.

    PubMed

    Chen, B; Zhuo, W

    2015-11-01

    Wire screens are widely used for sampling radioactive aerosols. The front-to-total activity ratio is a critical factor in describing the self-shielding effect of the wire screens. In this study, computational fluid dynamic method was applied to simulate the deposition of aerosols on the surface of the wire screens. Four different types of screens were investigated for particle size varying from 1 nm to 10 µm. Experimental verification was carried out in a radon chamber. The results showed good agreement between experimental data interception and the simulation. Significant differences on the front-to-total activity ratio for the different types of screens were observed when the size of particle was <20 nm.

  1. Autotrophic and heterotrophic abundance and activity associated with a nearshore front off the Georgia coast, U.S.A.

    NASA Astrophysics Data System (ADS)

    Jacobsen, T. R.; Pomeroy, L. R.; Blanton, J. O.

    1983-11-01

    The nearshore frontal zone off the coast of Georgia was found to be an area of high phytoplankton and bacterioplankton abundance and activity. Phytoplankton and bacterioplankton populations on the seaward side of the frontal zone had significantly higher photosynthetic and heterotrophic potentials than the nearshore side of the front. Phytoplankton species composition changed across the front, verifying that the front is a barrier to cross shelf mixing. Nearshore, large chain forming diatoms dominated, while smaller single cell diatoms and cyanobacteria dominated the seaward side of the front. Increased bacterioplankton activity was found associated with phytoplankton photosynthetic activity. Light appeared to be the major factor controlling photosynthesis across the frontal zone. Nitrogen, phosphorus and silica were present in similar concentrations, well above levels that would limit photosynthesis, on both sides of the front. Therefore the outflow of nutrients from rivers or estuaries did not influence primary production directly.

  2. Active Printed Materials for Complex Self-Evolving Deformations

    NASA Astrophysics Data System (ADS)

    Raviv, Dan; Zhao, Wei; McKnelly, Carrie; Papadopoulou, Athina; Kadambi, Achuta; Shi, Boxin; Hirsch, Shai; Dikovsky, Daniel; Zyracki, Michael; Olguin, Carlos; Raskar, Ramesh; Tibbits, Skylar

    2014-12-01

    We propose a new design of complex self-evolving structures that vary over time due to environmental interaction. In conventional 3D printing systems, materials are meant to be stable rather than active and fabricated models are designed and printed as static objects. Here, we introduce a novel approach for simulating and fabricating self-evolving structures that transform into a predetermined shape, changing property and function after fabrication. The new locally coordinated bending primitives combine into a single system, allowing for a global deformation which can stretch, fold and bend given environmental stimulus.

  3. Active printed materials for complex self-evolving deformations.

    PubMed

    Raviv, Dan; Zhao, Wei; McKnelly, Carrie; Papadopoulou, Athina; Kadambi, Achuta; Shi, Boxin; Hirsch, Shai; Dikovsky, Daniel; Zyracki, Michael; Olguin, Carlos; Raskar, Ramesh; Tibbits, Skylar

    2014-12-18

    We propose a new design of complex self-evolving structures that vary over time due to environmental interaction. In conventional 3D printing systems, materials are meant to be stable rather than active and fabricated models are designed and printed as static objects. Here, we introduce a novel approach for simulating and fabricating self-evolving structures that transform into a predetermined shape, changing property and function after fabrication. The new locally coordinated bending primitives combine into a single system, allowing for a global deformation which can stretch, fold and bend given environmental stimulus.

  4. Thermally Induced Deformation in Metallic Glass: the Activations and Relaxations

    NASA Astrophysics Data System (ADS)

    Fan, Yue; Iwashita, Takuya; Egami, Takeshi

    2015-03-01

    Thermally induced deformation in metallic glasses was investigated by sampling the potential energy landscape (PEL) and probing the changes in the atomic properties (e.g. energy, displacement, stress). The complete deformation processes consist of two stages: the activation (i.e. trigger, from initial minima to nearby saddle states on PEL), and relaxation (i.e. from saddle states to final minima on PEL). We show that the activation stages are triggered by local rearrangements of a small number of atoms, typically 5 atoms in average. Surprisingly, the individual triggers are invariant of the cooling history or elastic structure of the system. However, the organizations between different trigger centers can be varied and are related to the overall stability of the system. On the other hand, relaxation stages consist of two branches, a localized branch, and a cascade branch. While the localized branch is insensitive to the cooling history the system, the cascade branch is highly related with the processing conditions. In particular, for a faster quenched system, the cascade relaxation is found more prominent than in a slowly quenched system. The work is supported by Department of Energy.

  5. Front end optimization for the monolithic active pixel sensor of the ALICE Inner Tracking System upgrade

    NASA Astrophysics Data System (ADS)

    Kim, D.; Aglieri Rinella, G.; Cavicchioli, C.; Chanlek, N.; Collu, A.; Degerli, Y.; Dorokhov, A.; Flouzat, C.; Gajanana, D.; Gao, C.; Guilloux, F.; Hillemanns, H.; Hristozkov, S.; Junique, A.; Keil, M.; Kofarago, M.; Kugathasan, T.; Kwon, Y.; Lattuca, A.; Mager, M.; Sielewicz, K. M.; Marin Tobon, C. A.; Marras, D.; Martinengo, P.; Mazza, G.; Mugnier, H.; Musa, L.; Pham, T. H.; Puggioni, C.; Reidt, F.; Riedler, P.; Rousset, J.; Siddhanta, S.; Snoeys, W.; Song, M.; Usai, G.; Van Hoorne, J. W.; Yang, P.

    2016-02-01

    ALICE plans to replace its Inner Tracking System during the second long shut down of the LHC in 2019 with a new 10 m2 tracker constructed entirely with monolithic active pixel sensors. The TowerJazz 180 nm CMOS imaging Sensor process has been selected to produce the sensor as it offers a deep pwell allowing full CMOS in-pixel circuitry and different starting materials. First full-scale prototypes have been fabricated and tested. Radiation tolerance has also been verified. In this paper the development of the charge sensitive front end and in particular its optimization for uniformity of charge threshold and time response will be presented.

  6. Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation

    PubMed Central

    Cheeseman, Jacob R.; Thomason, Kelsey E.; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B.; Lamirande, Davora

    2016-01-01

    It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped “glaven”) for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object’s shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions–e.g., the participants’ performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision. PMID:26863531

  7. Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation.

    PubMed

    Norman, J Farley; Phillips, Flip; Cheeseman, Jacob R; Thomason, Kelsey E; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B; Lamirande, Davora

    2016-01-01

    It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped "glaven") for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object's shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions-e.g., the participants' performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision. PMID:26863531

  8. Sensing surface mechanical deformation using active probes driven by motor proteins

    PubMed Central

    Inoue, Daisuke; Nitta, Takahiro; Kabir, Arif Md. Rashedul; Sada, Kazuki; Gong, Jian Ping; Konagaya, Akihiko; Kakugo, Akira

    2016-01-01

    Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science. PMID:27694937

  9. Sensing surface mechanical deformation using active probes driven by motor proteins

    NASA Astrophysics Data System (ADS)

    Inoue, Daisuke; Nitta, Takahiro; Kabir, Arif Md. Rashedul; Sada, Kazuki; Gong, Jian Ping; Konagaya, Akihiko; Kakugo, Akira

    2016-10-01

    Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science.

  10. Seismic and satellite observations of calving activity at major glacier fronts in Greenland

    NASA Astrophysics Data System (ADS)

    Danesi, Stefania; Salimbeni, Simone; Urbini, Stefano; Pondrelli, Silvia; Margheriti, Lucia

    2016-04-01

    The interaction between oceans and large outlet glaciers in polar regions contributes to the budget of the global water cycle. We have observed the dynamic of sizeable outlet glaciers in Greenland by the analysis of seismic data collected by the regional seismic network Greenland Ice Sheet Monitoring Network (GLISN) trying also to find out correspondence in the glacier tongue evolution derived by the observation of satellite images. By studying the long-period seismic signals at stations located at the mouth of large fjords (e.g. ILULI, NUUG, KULLO), we identify major calving events through the detection of the ground flexure in response to seiche waves generated by iceberg detachments. 
For the time spanning the period between 2010-2014, we fill out calving-event catalogues which can be useful for the estimation of spatial and temporal variations in volume of ice loss at major active fronts in Greenland.

  11. Non-Invasive Measurement of Adrenocortical Activity in Blue-Fronted Parrots (Amazona aestiva, Linnaeus, 1758).

    PubMed

    Ferreira, João C P; Fujihara, Caroline J; Fruhvald, Erika; Trevisol, Eduardo; Destro, Flavia C; Teixeira, Carlos R; Pantoja, José C F; Schmidt, Elizabeth M S; Palme, Rupert

    2015-01-01

    Parrots kept in zoos and private households often develop psychological and behavioural disorders. Despite knowing that such disorders have a multifactorial aetiology and that chronic stress is involved, little is known about their development mainly due to a poor understanding of the parrots' physiology and the lack of validated methods to measure stress in these species. In birds, blood corticosterone concentrations provide information about adrenocortical activity. However, blood sampling techniques are difficult, highly invasive and inappropriate to investigate stressful situations and welfare conditions. Thus, a non-invasive method to measure steroid hormones is critically needed. Aiming to perform a physiological validation of a cortisone enzyme immunoassay (EIA) to measure glucocorticoid metabolites (GCM) in droppings of 24 Blue-fronted parrots (Amazona aestiva), two experiments were designed. During the experiments all droppings were collected at 3-h intervals. Initially, birds were sampled for 24 h (experiment 1) and one week later assigned to four different treatments (experiment 2): Control (undisturbed), Saline (0.2 mL of 0.9% NaCl IM), Dexamethasone (1 mg/kg IM) and Adrenocorticotropic hormone (ACTH; 25 IU IM). Treatments (always one week apart) were applied to all animals in a cross-over study design. A daily rhythm pattern in GCM excretion was detected but there were no sex differences (first experiment). Saline and dexamethasone treatments had no effect on GCM (not different from control concentrations). Following ACTH injection, GCM concentration increased about 13.1-fold (median) at the peak (after 3-9 h), and then dropped to pre-treatment concentrations. By a successful physiological validation, we demonstrated the suitability of the cortisone EIA to non-invasively monitor increased adrenocortical activity, and thus, stress in the Blue-fronted parrot. This method opens up new perspectives for investigating the connection between behavioural

  12. Non-Invasive Measurement of Adrenocortical Activity in Blue-Fronted Parrots (Amazona aestiva, Linnaeus, 1758)

    PubMed Central

    Ferreira, João C. P.; Fujihara, Caroline J.; Fruhvald, Erika; Trevisol, Eduardo; Destro, Flavia C.; Teixeira, Carlos R.; Pantoja, José C. F.; Schmidt, Elizabeth M. S.; Palme, Rupert

    2015-01-01

    Parrots kept in zoos and private households often develop psychological and behavioural disorders. Despite knowing that such disorders have a multifactorial aetiology and that chronic stress is involved, little is known about their development mainly due to a poor understanding of the parrots’ physiology and the lack of validated methods to measure stress in these species. In birds, blood corticosterone concentrations provide information about adrenocortical activity. However, blood sampling techniques are difficult, highly invasive and inappropriate to investigate stressful situations and welfare conditions. Thus, a non-invasive method to measure steroid hormones is critically needed. Aiming to perform a physiological validation of a cortisone enzyme immunoassay (EIA) to measure glucocorticoid metabolites (GCM) in droppings of 24 Blue-fronted parrots (Amazona aestiva), two experiments were designed. During the experiments all droppings were collected at 3-h intervals. Initially, birds were sampled for 24 h (experiment 1) and one week later assigned to four different treatments (experiment 2): Control (undisturbed), Saline (0.2 mL of 0.9% NaCl IM), Dexamethasone (1 mg/kg IM) and Adrenocorticotropic hormone (ACTH; 25 IU IM). Treatments (always one week apart) were applied to all animals in a cross-over study design. A daily rhythm pattern in GCM excretion was detected but there were no sex differences (first experiment). Saline and dexamethasone treatments had no effect on GCM (not different from control concentrations). Following ACTH injection, GCM concentration increased about 13.1-fold (median) at the peak (after 3–9 h), and then dropped to pre-treatment concentrations. By a successful physiological validation, we demonstrated the suitability of the cortisone EIA to non-invasively monitor increased adrenocortical activity, and thus, stress in the Blue-fronted parrot. This method opens up new perspectives for investigating the connection between behavioural

  13. Non-Invasive Measurement of Adrenocortical Activity in Blue-Fronted Parrots (Amazona aestiva, Linnaeus, 1758).

    PubMed

    Ferreira, João C P; Fujihara, Caroline J; Fruhvald, Erika; Trevisol, Eduardo; Destro, Flavia C; Teixeira, Carlos R; Pantoja, José C F; Schmidt, Elizabeth M S; Palme, Rupert

    2015-01-01

    Parrots kept in zoos and private households often develop psychological and behavioural disorders. Despite knowing that such disorders have a multifactorial aetiology and that chronic stress is involved, little is known about their development mainly due to a poor understanding of the parrots' physiology and the lack of validated methods to measure stress in these species. In birds, blood corticosterone concentrations provide information about adrenocortical activity. However, blood sampling techniques are difficult, highly invasive and inappropriate to investigate stressful situations and welfare conditions. Thus, a non-invasive method to measure steroid hormones is critically needed. Aiming to perform a physiological validation of a cortisone enzyme immunoassay (EIA) to measure glucocorticoid metabolites (GCM) in droppings of 24 Blue-fronted parrots (Amazona aestiva), two experiments were designed. During the experiments all droppings were collected at 3-h intervals. Initially, birds were sampled for 24 h (experiment 1) and one week later assigned to four different treatments (experiment 2): Control (undisturbed), Saline (0.2 mL of 0.9% NaCl IM), Dexamethasone (1 mg/kg IM) and Adrenocorticotropic hormone (ACTH; 25 IU IM). Treatments (always one week apart) were applied to all animals in a cross-over study design. A daily rhythm pattern in GCM excretion was detected but there were no sex differences (first experiment). Saline and dexamethasone treatments had no effect on GCM (not different from control concentrations). Following ACTH injection, GCM concentration increased about 13.1-fold (median) at the peak (after 3-9 h), and then dropped to pre-treatment concentrations. By a successful physiological validation, we demonstrated the suitability of the cortisone EIA to non-invasively monitor increased adrenocortical activity, and thus, stress in the Blue-fronted parrot. This method opens up new perspectives for investigating the connection between behavioural

  14. Front structure and dynamics in dense colonies of motile bacteria: Role of active turbulence

    NASA Astrophysics Data System (ADS)

    Chatterjee, Rayan; Joshi, Abhijeet A.; Perlekar, Prasad

    2016-08-01

    We study the spreading of a bacterial colony undergoing turbulentlike collective motion. We present two minimalistic models to investigate the interplay between population growth and coherent structures arising from turbulence. Using direct numerical simulation of the proposed models we find that turbulence has two prominent effects on the spatial growth of the colony: (a) the front speed is enhanced, and (b) the front gets crumpled. Both these effects, which we highlight by using statistical tools, are markedly different in our two models. We also show that the crumpled front structure and the passive scalar fronts in random flows are related in certain regimes.

  15. Front structure and dynamics in dense colonies of motile bacteria: Role of active turbulence.

    PubMed

    Chatterjee, Rayan; Joshi, Abhijeet A; Perlekar, Prasad

    2016-08-01

    We study the spreading of a bacterial colony undergoing turbulentlike collective motion. We present two minimalistic models to investigate the interplay between population growth and coherent structures arising from turbulence. Using direct numerical simulation of the proposed models we find that turbulence has two prominent effects on the spatial growth of the colony: (a) the front speed is enhanced, and (b) the front gets crumpled. Both these effects, which we highlight by using statistical tools, are markedly different in our two models. We also show that the crumpled front structure and the passive scalar fronts in random flows are related in certain regimes. PMID:27627334

  16. Significance of an Active Volcanic Front in the Far Western Aleutian Arc

    NASA Astrophysics Data System (ADS)

    Yogodzinski, G. M.; Kelemen, P. B.; Hoernle, K.

    2015-12-01

    Discovery of a volcanic front west of Buldir Volcano, the western-most emergent Aleutian volcano, demonstrates that the surface expression of Aleutian volcanism falls below sea level just west of 175.9° E longitude, but is otherwise continuous from mainland Alaska to Kamchatka. The newly discovered sites of western Aleutian seafloor volcanism are the Ingenstrem Depression, a 60 km-long structural depression just west of Buldir, and an unnamed area 300 km further west, referred to as the Western Cones. These locations fall along a volcanic front that stretches from Buldir to Piip Seamount near the Komandorsky Islands. Western Aleutian seafloor volcanic rocks include large quantities of high-silica andesite and dacite, which define a highly calc-alkaline igneous series and carry trace element signatures that are unmistakably subduction-related. This indicates that subducting oceanic lithosphere is present beneath the westernmost Aleutian arc. The rarity of earthquakes below depths of 200 km indicates that the subducting plate is unusually hot. Some seafloor volcanoes are 6-8 km wide at the base, and so are as large as many emergent Aleutian volcanoes. The seafloor volcanoes are submerged in water depths >3000 m because they sit on oceanic lithosphere of the Bering Sea. The volcanic front is thus displaced to the north of the ridge of arc crust that underlies the western Aleutian Islands. This displacement, which developed since approximately 6 Ma when volcanism was last active on the islands, must be a consequence of oblique convergence in a system where the subducting plate and large blocks of arc crust are both moving primarily in an arc-parallel sense. The result is a hot-slab system where low subduction rates probably limit advection of hot mantle to the subarc, and produce a relatively cool and perhaps stagnant mantle wedge. The oceanic setting and highly oblique subduction geometry also severely limit rates of sediment subduction, so the volcanic rocks, which

  17. Mechanics of dielectric elastomer-activated deformable transmission grating

    NASA Astrophysics Data System (ADS)

    Wang, Yin; Zhou, Jinxiong; Sun, Wenjie; Wu, Xiaohong; Zhang, Ling

    2014-09-01

    Laminating a thin layer of elastomeric grating on the surface of a prestretched dielectric elastomer (DE) membrane forms a basic design of electrically tunable transmission grating. We analyze the inhomogeneous deformation of a circular multiple-region configuration. Variation of the geometric and material parameters, as well as of the critical condition determined by loss of tension instability, is probed to aid the design of a DE-based deformable grating. The predicted changes in the grating period agree substantially with the experimental results reported by Aschwanden et al (Aschwanden et al 2007 IEEE Photon. Technol. Lett. 19 1090).

  18. PLEKHG3 enhances polarized cell migration by activating actin filaments at the cell front.

    PubMed

    Nguyen, Trang Thi Thu; Park, Wei Sun; Park, Byung Ouk; Kim, Cha Yeon; Oh, Yohan; Kim, Jin Man; Choi, Hana; Kyung, Taeyoon; Kim, Cheol-Hee; Lee, Gabsang; Hahn, Klaus M; Meyer, Tobias; Heo, Won Do

    2016-09-01

    Cells migrate by directing Ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division control protein 42 (Cdc42) activities and by polymerizing actin toward the leading edge of the cell. Previous studies have proposed that this polarization process requires a local positive feedback in the leading edge involving Rac small GTPase and actin polymerization with PI3K likely playing a coordinating role. Here, we show that the pleckstrin homology and RhoGEF domain containing G3 (PLEKHG3) is a PI3K-regulated Rho guanine nucleotide exchange factor (RhoGEF) for Rac1 and Cdc42 that selectively binds to newly polymerized actin at the leading edge of migrating fibroblasts. Optogenetic inactivation of PLEKHG3 showed that PLEKHG3 is indispensable both for inducing and for maintaining cell polarity. By selectively binding to newly polymerized actin, PLEKHG3 promotes local Rac1/Cdc42 activation to induce more local actin polymerization, which in turn promotes the recruitment of more PLEKHG3 to induce and maintain cell front. Thus, autocatalytic reinforcement of PLEKHG3 localization to the leading edge of the cell provides a molecular basis for the proposed positive feedback loop that is required for cell polarization and directed migration. PMID:27555588

  19. PLEKHG3 enhances polarized cell migration by activating actin filaments at the cell front

    PubMed Central

    Nguyen, Trang Thi Thu; Park, Wei Sun; Park, Byung Ouk; Kim, Cha Yeon; Oh, Yohan; Kim, Jin Man; Choi, Hana; Kyung, Taeyoon; Kim, Cheol-Hee; Lee, Gabsang; Hahn, Klaus M.; Meyer, Tobias; Heo, Won Do

    2016-01-01

    Cells migrate by directing Ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division control protein 42 (Cdc42) activities and by polymerizing actin toward the leading edge of the cell. Previous studies have proposed that this polarization process requires a local positive feedback in the leading edge involving Rac small GTPase and actin polymerization with PI3K likely playing a coordinating role. Here, we show that the pleckstrin homology and RhoGEF domain containing G3 (PLEKHG3) is a PI3K-regulated Rho guanine nucleotide exchange factor (RhoGEF) for Rac1 and Cdc42 that selectively binds to newly polymerized actin at the leading edge of migrating fibroblasts. Optogenetic inactivation of PLEKHG3 showed that PLEKHG3 is indispensable both for inducing and for maintaining cell polarity. By selectively binding to newly polymerized actin, PLEKHG3 promotes local Rac1/Cdc42 activation to induce more local actin polymerization, which in turn promotes the recruitment of more PLEKHG3 to induce and maintain cell front. Thus, autocatalytic reinforcement of PLEKHG3 localization to the leading edge of the cell provides a molecular basis for the proposed positive feedback loop that is required for cell polarization and directed migration. PMID:27555588

  20. Modeling crustal deformation near active faults and volcanic centers: a catalog of deformation models and modeling approaches

    USGS Publications Warehouse

    Battaglia, Maurizio; ,; Peter, F.; Murray, Jessica R.

    2013-01-01

    This manual provides the physical and mathematical concepts for selected models used to interpret deformation measurements near active faults and volcanic centers. The emphasis is on analytical models of deformation that can be compared with data from the Global Positioning System (GPS) receivers, Interferometric synthetic aperture radar (InSAR), leveling surveys, tiltmeters and strainmeters. Source models include pressurized spherical, ellipsoidal, and horizontal penny-shaped geometries in an elastic, homogeneous, flat half-space. Vertical dikes and faults are described following the mathematical notation for rectangular dislocations in an elastic, homogeneous, flat half-space. All the analytical expressions were verified against numerical models developed by use of COMSOL Multyphics, a Finite Element Analysis software (http://www.comsol.com). In this way, typographical errors present were identified and corrected. Matlab scripts are also provided to facilitate the application of these models.

  1. Are boundary conditions in surface productivity at the Southern Polar Front reflected in benthic activity?

    NASA Astrophysics Data System (ADS)

    Brandt, Angelika; Vanreusel, Ann; Bracher, Astrid; Jule Marie Hoppe, Clara; Lins, Lidia; Meyer-Löbbecke, Anna; Altenburg Soppa, Mariana; Würzberg, Laura

    2014-10-01

    In austral summer 2012, during the expedition ANT-XXVIII/3 on board RV Polarstern, two sites were sampled 1600 km apart in the South Polar Front area (52°S) at the boundary of different productivity regimes for meio- and macrobenthos using a multiple-corer and an epibenthic sledge, respectively. Patterns in density and abundance data were compared between different size classes of the benthos and interpreted in relation to surface primary productivity data and sediment oxygen consumption. We tested the hypothesis that long-term satellite-derived surface phytoplankton biomass, in situ real time biomass, and productivity measurements at the surface and throughout the euphotic zone are reflected in abyssal benthos densities, abundances and activity. Specifically, we investigated the effect of boundary conditions for lower and higher surface productivity. Surface and integrated to 100 m depth biomass and primary productivity measurements vary stations, with the lowest values at station 85 (0.083 mg Chl-a m-3 at surface, 9 mg Chl-a m-2 and 161 mg C m-2 d-1- integrated over the first 100 m depth), and the highest values at station 86 (2.231 mg Chl-a m-3 at surface, 180 mg Chl-a m-2 and 2587 mg C m-2 d-1 integrated over first 100 m depth). Total meiofaunal densities varied between 102 and 335 individuals/10 cm². Densities were the highest at station 86-30 (335 individuals) and lowest at station 81-13 (102 individuals). Total macrofaunal densities (individuals/1000 m²) varied between 26 individuals at station 81-17 and 194 individuals at station 86-24. However, three EBS hauls were taken at station 86 with a minimum of 80 and a maximum of 194 individuals. Sediment oxygen consumption did not vary significantly between stations from east to west. Bentho-pelagic coupling of meio- and macrobenthic communities could not be observed in the South Polar Front at the boundary conditions from low to high surface productivity between stations 81 and 86.

  2. Mouthpart deformities and nucleolus activity in field-collected Chironomus riparius larvae.

    PubMed

    Meregalli, G; Bettinetti, R; Pluymers, L; Vermeulen, A C; Rossaro, B; Ollevier, F

    2002-05-01

    Chironomid mouthpart deformities and aberrations of their polytenic chromosomes are sublethal responses to toxic stress. These endpoints have been used in several cases as bioindications for sediment pollution. In the present study we aimed to establish whether there was an association between mouthpart deformities and nucleolus activity in the polytenic chromosomes. Such information could be useful to gain insight into the mechanisms involved in the occurrence of mouthpart deformities and their consequences on the larvae. Third-instar larvae of Chironomus riparius were collected at a site downstream of a sewage treatment plant mostly contaminated by pesticides. Larvae were then raised in the laboratory in aquaria containing sediment and water from the study location. During a 16-day period, larvae ready to molt to the fourth instar were reared individually. Within a few hours of their molt, the larvae were preserved. The presence of mouthpart deformities (mentum, mandibles, and pecten epipharyngis) and the percentage of active nucleoli were assessed. Those larvae presenting mentum deformities had a significantly higher incidence of active nucleoli in their polytenic chromosomes than nondeformed larvae. Because a high number of active nucleoli generally indicates increased rRNA synthesis, deformed larvae seemed to exhibit a higher protein synthesis than normal individuals. The synthesis of additional proteins may increase deformed larva tolerance to toxicants. PMID:11994780

  3. Extremely reduced motion in front of screens: investigating real-world physical activity of adolescents by accelerometry and electronic diary.

    PubMed

    Streb, Judith; Kammer, Thomas; Spitzer, Manfred; Hille, Katrin

    2015-01-01

    This paper reports accelerometer and electronic dairy data on typical daily activities of 139 school students from grade six and nine. Recordings covered a typical school day for each student and lasted on average for 23 h. Screen activities (watching television and using the computer) are compared to several other activities performed while sitting (e.g., playing, eating, sitting in school, and doing homework). Body movement was continuously recorded by four accelerometers and transformed into a motion sore. Our results show that extremely low motion scores, as if subjects were freezing, emerge to a greater extent in front of screens compared to other investigated activities. Given the substantial amount of time young people spend in front of screens and the rising obesity epidemic, our data suggest a mechanism for the association of screen time and obesity. PMID:25955531

  4. Active deformation in Western Turkey: new GPS observations and models

    NASA Astrophysics Data System (ADS)

    Nocquet, J.; Aktug, B.; Parsons, B.; Cingoz, A.; England, P.; Erkan, Y.; Soyer, N.; Akdeniz, H.; Kilicoglu, A.

    2007-12-01

    How the continents deform remains a matter of debate. One view postulates that continental deforming zones are comprised of a limited numbers of rigid (elastic) microplates. If true, the surface motion can then be described by the relative rotation of blocks, and strain should be localized along the major faults separating the blocks. An alternative view is that the deformation at depth is distributed over wide areas, can be modelled by a viscous flow responding to boundary conditions applied on it and gravitational potential energy gradients related to variations in topography, and the surface strain simply reflects this deformation. Western Turkey is a region of crustal extension, part of the Nubia/Eurasia plate boundary. Its kinematics is often modelled by the relative motion of a small number of rigid blocks (Nyst & Thatcher, 2005, Reilinger et al., 2006). However, until now, the limited number of GPS velocity vectors available has prevented a detailed examination of which is the more appropriate description. We present a new geodetic velocity field including ~100 sites from the longitude the Central Anatolian plateau to the Aegean coast, derived from a combination of campaigns carried out between 1997 and 2006, and continuous GPS operating since 2003, which we use to test the different models. While the kinematics of the area can be correctly modelled by a block model, a good fit to the velocity field requires blocks with sizes smaller than 100 km and still fails to adequately predict the strain rate observed within blocks . Alternatively, we test an approach where the lithosphere is modelled as a thin viscous sheet, responding to the gravitational potentiel energy contrast between the high plateau of eastern Turkey to the east and the subduction along the Hellenic trench in the southwest. The simplistic model has only one free parameter (the force applied by the subducting oceanic lithosphere on the Aegean ), but provides a good agreement with the observed

  5. Active fibers: matching deformable tract templates to diffusion tensor images.

    PubMed

    Eckstein, Ilya; Shattuck, David W; Stein, Jason L; McMahon, Katie L; de Zubicaray, Greig; Wright, Margaret J; Thompson, Paul M; Toga, Arthur W

    2009-08-01

    Reliable quantitative analysis of white matter connectivity in the brain is an open problem in neuroimaging, with common solutions requiring tools for fiber tracking, tractography segmentation and estimation of intersubject correspondence. This paper proposes a novel, template matching approach to the problem. In the proposed method, a deformable fiber-bundle model is aligned directly with the subject tensor field, skipping the fiber tracking step. Furthermore, the use of a common template eliminates the need for tractography segmentation and defines intersubject shape correspondence. The method is validated using phantom DTI data and applications are presented, including automatic fiber-bundle reconstruction and tract-based morphometry.

  6. Deformation of partially pumped active mirrors for high average-power diode-pumped solid-state lasers.

    PubMed

    Albach, Daniel; LeTouzé, Geoffroy; Chanteloup, Jean-Christophe

    2011-04-25

    We discuss the deformation of a partially pumped active mirror amplifier as a free standing disk, as implemented in several laser systems. We rely on the Lucia laser project to experimentally evaluate the analytical and numerical deformation models. PMID:21643092

  7. Temperature activated absorption during laser-induced damage: The evolution of laser-supported solid-state absorption fronts

    SciTech Connect

    Carr, C W; Bude, J D; Shen, N; Demange, P

    2010-10-26

    Previously we have shown that the size of laser induced damage sites in both KDP and SiO{sub 2} is largely governed by the duration of the laser pulse which creates them. Here we present a model based on experiment and simulation that accounts for this behavior. Specifically, we show that solid-state laser-supported absorption fronts are generated during a damage event and that these fronts propagate at constant velocities for laser intensities up to 4 GW/cm{sup 2}. It is the constant absorption front velocity that leads to the dependence of laser damage site size on pulse duration. We show that these absorption fronts are driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport, and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. In addition to the practical application of selecting an optimal laser for pre-initiation of large aperture optics, this work serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

  8. Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

    USGS Publications Warehouse

    Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

    2010-01-01

    This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

  9. PMCA activity and membrane tubulin affect deformability of erythrocytes from normal and hypertensive human subjects.

    PubMed

    Monesterolo, Noelia E; Nigra, Ayelen D; Campetelli, Alexis N; Santander, Verónica S; Rivelli, Juan F; Arce, Carlos A; Casale, Cesar H

    2015-11-01

    Our previous studies demonstrated formation of a complex between acetylated tubulin and brain plasma membrane Ca(2+)-ATPase (PMCA), and the effect of the lipid environment on structure of this complex and on PMCA activity. Deformability of erythrocytes from hypertensive human subjects was reduced by an increase in membrane tubulin content. In the present study, we examined the regulation of PMCA activity by tubulin in normotensive and hypertensive erythrocytes, and the effect of exogenously added diacylglycerol (DAG) and phosphatidic acid (PA) on erythrocyte deformability. Some of the key findings were that: (i) PMCA was associated with tubulin in normotensive and hypertensive erythrocytes, (ii) PMCA enzyme activity was directly correlated with erythrocyte deformability, and (iii) when tubulin was present in the erythrocyte membrane, treatment with DAG or PA led to increased deformability and associated PMCA activity. Taken together, our findings indicate that PMCA activity is involved in deformability of both normotensive and hypertensive erythrocytes. This rheological property of erythrocytes is affected by acetylated tubulin and its lipid environment because both regulate PMCA activity.

  10. The role of mechanical heterogeneities in evaporite sequence during deformation initiated by basement fault activity

    NASA Astrophysics Data System (ADS)

    Adamuszek, Marta; Dabrowski, Marcin; Burliga, Stanisław

    2016-04-01

    Kłodawa Salt Structure (KSS) situated in the centre of the Polish Zechstein Basin started to rise above a basement fault in the Early Triassic. Geological studies of the KSS revealed significant differences in the deformation patterns between the PZ1-PZ2 (intensely deformed) and PZ3-PZ4 (less deformed) cycle evaporites. These two older and two younger cycle evaporite complexes are separated by the thick Main Anhydrite (A3) bed. We use numerical simulations to assess the impact of a thick anhydrite bed on intrasalt deformation. In our models, the overburden consists of clastic sediments. A normal fault located in the rigid basement beneath the salt is activated due to model extension. At the same time, the sedimentation process takes place. The evaporites consist of a salt bed intercalated with a thick anhydrite layer of varying position and geometry. To understand the role of anhydrite layer, we run comparative simulations, in which no anhydrite layer is present. In the study, we use our own numerical codes implemented in MATLAB combined with the MILAMIN and MUTILS numerical packages. Our investigations revealed a significant influence of the anhydrite on deformation style in the evaporate series. The supra-anhydrite domain is characterized by weaker deformation and lower rates of salt flow in comparison to the sub-anhydrite domain. The highest contrast in the rate of salt flow between the two domains is observed in the case of the anhydrite layer situated close to the bottom of the salt complex. The thick anhydrite layer additionally diminishes the deformation rate in the supra-anhydrite domain and can lead to detachment of the basement deformation from its overlay. Our numerical simulations showed that the presence of the A3 Main Anhydrite bed could be the dominant factor responsible for the decoupling of deformation in the KSS salt complex.

  11. Constraining deformation history and recent activity along the Tuz Gölü fault zone, Central Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Krystopowicz, N. J.; Schoenbohm, L. M.; Cosca, M. A.

    2013-12-01

    The 200 km long, dextral, transtensive Tuz Gölü fault zone is a prominent northwest-striking feature in Central Anatolia. It is one of the most significant structures in Central Anatolia in that it lies within the transition zone between the Western Anatolian Extensional Province and the Eastern Anatolian Contractional Province; its study therefore offers valuable insight into how Central Anatolia is affected by lateral extrusion related to collision in the east, and gravitational pull forces associated with subduction in the west. Proposals for the initiation of the Tuz Gölü fault zone range from Cretaceous to Neogene times, and the amount of recent activity along this fault system remains poorly constrained. Furthermore, potential basinward migration of deformation into the Tuz Gölü basin poses the question as to whether or not this fault system is active in the Holocene. Previous work suggests that migration of deformation towards the basin interior may be related to lithospheric-scale processes such as plateau development, microplate extrusion, or the onset of crustal thinning associated with slab-tear propagation in subducting African lithosphere. In this study, we use a combination of paleostress and morpho-tectonic analysis to further delineate the segmentation and present activity of the Tuz Gölü fault zone. Paleostress analysis offers insight into the deformation history of the region as well as the modern-day stress regime. We conducted a morphometric analysis of over 300 drainage basins along the range-front, which reveal variations that characterize the unique development of numerous fault strands in the region. Statistical analysis of hypsometric curves, systematic variation in basin morphology and orientation, as well as changes in mountain-front sinuosity reveal fault segmentation. Additionally, field mapping and Ar-Ar dating of offset lava flows from the Hasan Dag Volcano quantitatively constrain slip-rates in the southeastern portion of the

  12. Identification and Active Exploration of Deformable Object Boundary Constraints through Robotic Manipulation

    PubMed Central

    Boonvisut, Pasu; Cavusoglu, M. Cenk

    2014-01-01

    Robotic motion planning algorithms for manipulation of deformable objects, such as in medical robotics applications, rely on accurate estimations of object deformations that occur during manipulation. An estimation of the tissue response (for off-line planning or real-time on-line re-planning), in turn, requires knowledge of both object constitutive parameters and boundary constraints. In this paper, a novel algorithm for estimating boundary constraints of deformable objects from robotic manipulation data is presented. The proposed algorithm uses tissue deformation data collected with a vision system, and employs a multi-stage hill climbing procedure to estimate the boundary constraints of the object. An active exploration technique, which uses an information maximization approach, is also proposed to extend the identification algorithm. The effects of uncertainties on the proposed methods are analyzed in simulation. The results of experimental evaluation of the methods are also presented. PMID:25684836

  13. Detection and Analysis of Deep Seated Gravitational Slope Deformation and Relations with the Active Tectonics

    NASA Astrophysics Data System (ADS)

    Moro, M.; Saroli, M.; Lancia, M.; Albano, M.; Lo Sardo, L.; Stramondo, S.

    2015-12-01

    Modern geomorphological investigations focused on the definition of major factors conditioning the landscape evolution. The interaction of some of these factors as the litho-structural setting, the local relief, the tectonic activity, the climatic conditions and the seismicity plays a key-role in determining large scale slope instability phenomena which display the general morphological features of deep seated gravitational deformations (DSGD). The present work aims to detect the large scale gravitational deformation and relations with the active tectonics affecting the Abruzzo Region and to provide a description of the morphologic features of the deformations by means of aerial photograph interpretation, geological/geomorphological field surveys and DInSAR data. The investigated areas are morphologically characterized by significant elevation changes due to the presence of high mountain peaks, separated from surrounding depressed areas by steep escarpments, frequently represented by active faults. Consequently, relief energy favours the development of gravity-driven deformations. These deformations seem to be superimposed on and influenced by the inherited structural and tectonic pattern, related to the sin- and post-thrusting evolution. The morphological evidences of these phenomena, are represented by landslides, sackungen or rock-flows, lateral spreads and block slides. DInSAR analysis measured deformation of the large scale gravitative phenomena previously identified through aerial-photo analysis. DSGD may evolve in rapid, catastrophic mass movements and this paroxistic evolution of the deformations may be triggered by high magnitude seismic events. These assumptions point out the great importance of mapping in detail large scale slope instability phenomena in relation to the active faults, in a perspective of land-use planning such as the Abruzzo Region characterized by a high magnitude historical seismicity.

  14. Active zone impact on deformation state of non-rigid pavement

    NASA Astrophysics Data System (ADS)

    Mandula, Ján

    2014-06-01

    The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper

  15. Cyclic mechanical deformation stimulates human lung fibroblast proliferation and autocrine growth factor activity.

    PubMed

    Bishop, J E; Mitchell, J J; Absher, P M; Baldor, L; Geller, H A; Woodcock-Mitchell, J; Hamblin, M J; Vacek, P; Low, R B

    1993-08-01

    Cellular hypertrophy and hyperplasia and increased extracellular matrix deposition are features of tissue hypertrophy resulting from increased work load. It is known, for example, that mechanical forces play a critical role in lung development, cardiovascular remodeling following pressure overload, and skeletal muscle growth. The mechanisms involved in these processes, however, remain unclear. Here we examined the effect of mechanical deformation on fibroblast function in vitro. IMR-90 human fetal lung fibroblasts grown on collagen-coated silastic membranes were subjected to cyclical mechanical deformation (10% increase in culture surface area; 1 Hz) for up to 5 days. Cell number was increased by 39% after 2 days of deformation (1.43 +/- .01 x 10(5) cells/membrane compared with control, 1.03 +/- 0.02 x 10(5) cells; mean +/- SEM; P < 0.02) increasing to 163% above control by 4 days (2.16 +/- 0.16 x 10(5) cells compared with 0.82 +/- 0.03 x 10(5) cells; P < 0.001). The medium from mechanically deformed cells was mitogenic for IMR-90 cells, with maximal activity in the medium from cells mechanically deformed for 2 days (stimulating cell replication by 35% compared with media control; P < 0.002). These data suggest that mechanical deformation stimulates human lung fibroblast replication and that this effect is mediated by the release of autocrine growth factors.

  16. Muscle activation characteristics of the front leg during baseball swings with timing correction for sudden velocity decrease.

    PubMed

    Ohta, Yoichi; Nakamoto, Hiroki; Ishii, Yasumitsu; Ikudome, Sachi; Takahashi, Kyohei; Shima, Norihiro

    2014-01-01

    This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions. The type of muscle activation during swings in response to decreased velocity condition was both monophasic and biphasic. When biphasic activation appeared in response to decreased velocity, the impact time and the time to peak EMG amplitude were significantly prolonged and the timing error was significantly smaller than that of monophasic activation. However, the EMG onset from the target start was consistent both monophasic and biphasic activation in response to conditions of decreased velocity. In addition, batters with small timing errors in response to decreased velocity were more likely to generate biphasic EMG activation. These findings indicated that timing correction for a sudden decrease in the velocity of an oncoming target is achieved by modifying the muscle activation characteristics of the vastus lateralis muscle of front leg from monophasic to biphasic to delay reaching peak muscle activation and thus prolong impact time. Therefore, the present findings suggests that the extent of timing errors in response to decreased velocity is influenced by the ability to correct muscle activation after its initiation rather than by delaying the initiation timing of muscle activation during baseball swings.

  17. Muscle activation characteristics of the front leg during baseball swings with timing correction for sudden velocity decrease.

    PubMed

    Ohta, Yoichi; Nakamoto, Hiroki; Ishii, Yasumitsu; Ikudome, Sachi; Takahashi, Kyohei; Shima, Norihiro

    2014-01-01

    This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions. The type of muscle activation during swings in response to decreased velocity condition was both monophasic and biphasic. When biphasic activation appeared in response to decreased velocity, the impact time and the time to peak EMG amplitude were significantly prolonged and the timing error was significantly smaller than that of monophasic activation. However, the EMG onset from the target start was consistent both monophasic and biphasic activation in response to conditions of decreased velocity. In addition, batters with small timing errors in response to decreased velocity were more likely to generate biphasic EMG activation. These findings indicated that timing correction for a sudden decrease in the velocity of an oncoming target is achieved by modifying the muscle activation characteristics of the vastus lateralis muscle of front leg from monophasic to biphasic to delay reaching peak muscle activation and thus prolong impact time. Therefore, the present findings suggests that the extent of timing errors in response to decreased velocity is influenced by the ability to correct muscle activation after its initiation rather than by delaying the initiation timing of muscle activation during baseball swings. PMID:25918848

  18. Muscle Activation Characteristics of the Front Leg During Baseball Swings with Timing Correction for Sudden Velocity Decrease

    PubMed Central

    Ohta, Yoichi; Nakamoto, Hiroki; Ishii, Yasumitsu; Ikudome, Sachi; Takahashi, Kyohei; Shima, Norihiro

    2015-01-01

    This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions. The type of muscle activation during swings in response to decreased velocity condition was both monophasic and biphasic. When biphasic activation appeared in response to decreased velocity, the impact time and the time to peak EMG amplitude were significantly prolonged and the timing error was significantly smaller than that of monophasic activation. However, the EMG onset from the target start was consistent both monophasic and biphasic activation in response to conditions of decreased velocity. In addition, batters with small timing errors in response to decreased velocity were more likely to generate biphasic EMG activation. These findings indicated that timing correction for a sudden decrease in the velocity of an oncoming target is achieved by modifying the muscle activation characteristics of the vastus lateralis muscle of front leg from monophasic to biphasic to delay reaching peak muscle activation and thus prolong impact time. Therefore, the present findings suggests that the extent of timing errors in response to decreased velocity is influenced by the ability to correct muscle activation after its initiation rather than by delaying the initiation timing of muscle activation during baseball swings. PMID:25918848

  19. Laboratory experiments on fronts

    NASA Astrophysics Data System (ADS)

    Chia, F.; Griffiths, R. W.; Linden, P. F.

    We describe a laboratory model of an upwelling front in a two-layer stratification. In the model the interface between the two layers slopes upwards toward a vertical boundary (or coastline) and can intersect the free surface to produce a front. Fluid motion in each layer is density driven and, in the undisturbed state, is in quasi-geostrophic balance. The front is observed to be unstable to (ageostrophic) disturbances with an along-front wavelength proportional to the Rossby radius of deformation. At very large amplitudes these unstable waves form closed circulations. However, in contrast to the behaviour of fronts far from vertical boundaries, where cyclone-anticyclone vortex pairs are formed, the presence of the coastline inhibits formation of anticyclonic eddies in the upper layer and enhances cyclonic rings of upper layer fluid which lie above cyclonic eddies in the lower layer. The cyclones move away from the vertical boundary and (as is also the case when no vertical boundary is present) they appear at the surface as eddies containing lower layer fluid on the seaward side of the mean frontal position.

  20. Fronts, fish, and predators

    NASA Astrophysics Data System (ADS)

    Belkin, Igor M.; Hunt, George L.; Hazen, Elliott L.; Zamon, Jeannette E.; Schick, Robert S.; Prieto, Rui; Brodziak, Jon; Teo, Steven L. H.; Thorne, Lesley; Bailey, Helen; Itoh, Sachihiko; Munk, Peter; Musyl, Michael K.; Willis, Jay K.; Zhang, Wuchang

    2014-09-01

    Ocean fronts play a key role in marine ecosystems. Fronts shape oceanic landscapes and affect every trophic level across a wide range of spatio-temporal scales, from meters to thousands of kilometers, and from days to millions of years. At some fronts, there is an elevated rate of primary production, whereas at others, plankton is aggregated by advection and by the behavior of organisms moving against gradients in temperature, salinity, light irradiance, hydrostatic pressure and other physico-chemical and biological factors. Lower trophic level organisms - phytoplankton and zooplankton - that are aggregated in sufficient densities, attract organisms from higher trophic levels, from planktivorous schooling fish to squid, large piscivorous fish, seabirds and marine mammals. Many species have critical portions of their life stages or behaviors closely associated with fronts, including spawning, feeding, ontogenetic development, migrations, and other activities cued to frontal dynamics. At different life stages, an individual species or population might be linked to different fronts. The nature and strength of associations between fronts and biota depend on numerous factors such as the physical nature and spatio-temporal scales of the front and the species and their life stages in question. In other words, fronts support many different niches and micro/macro-habitats over a wide range of spatial and temporal scales.

  1. Estimating Active Layer Thickness from Remotely Sensed Surface Deformation

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Zhang, T.; Wahr, J. M.

    2010-12-01

    We estimate active layer thickness (ALT) from remotely sensed surface subsidence during thawing seasons derived from interferometric synthetic aperture radar (InSAR) measurements. Ground ice takes up more volume than ground water, so as the soil thaws in summer and the active layer deepens, the ground subsides. The volume of melted ground water during the summer thaw determines seasonal subsidence. ALT is defined as the maximum thaw depth at the end of a thawing season. By using InSAR to measure surface subsidence between the start and end of summer season, one can estimate the depth of thaw over a large area (typically 100 km by 100 km). We developed an ALT retrieval algorithm integrating InSAR-derived surface subsidence, observed soil texture, organic matter content, and moisture content. We validated this algorithm in the continuous permafrost area on the North Slope of Alaska. Based on InSAR measurements using ERS-1/2 SAR data, our estimated values match in situ measurements of ALT within 1--10 cm at Circumpolar Active Layer Monitoring (CALM) sites within the study area. The active layer plays a key role in land surface processes in cold regions. Current measurements of ALT using mechanical probing, frost/thaw tubes, or inferred from temperature measurements are of high quality, but limited in spatial coverage. Using InSAR to estimate ALT greatly expands the spatial coverage of ALT observations.

  2. A deformable lung tumor tracking method in fluoroscopic video using active shape models: a feasibility study.

    PubMed

    Xu, Qianyi; Hamilton, Russell J; Schowengerdt, Robert A; Jiang, Steve B

    2007-09-01

    A dynamic multi-leaf collimator (DMLC) can be used to track a moving target during radiotherapy. One of the major benefits for DMLC tumor tracking is that, in addition to the compensation for tumor translational motion, DMLC can also change the aperture shape to conform to a deforming tumor projection in the beam's eye view. This paper presents a method that can track a deforming lung tumor in fluoroscopic video using active shape models (ASM) (Cootes et al 1995 Comput. Vis. Image Underst. 61 38-59). The method was evaluated by comparing tracking results against tumor projection contours manually edited by an expert observer. The evaluation shows the feasibility of using this method for precise tracking of lung tumors with deformation, which is important for DMLC-based real-time tumor tracking.

  3. Active range of motion outcomes after reconstruction of burned wrist and hand deformities.

    PubMed

    Afifi, Ahmed M; Mahboub, Tarek A; Ibrahim Fouad, Amr; Azari, Kodi; Khalil, Haitham H; McCarthy, James E

    2016-06-01

    This works aim is to evaluate the efficacy of skin grafts and flaps in reconstruction of post-burn hand and wrist deformities. A prospective study of 57 burn contractures of the wrist and dorsum of the hand was performed. Flaps were used only if there was a non-vascularized structure after contracture release, otherwise a skin graft was used. Active range of motion (ROM) was used to assess hand function. The extension deformity cohort uniformly underwent skin graft following contracture release with a mean improvement of 71 degrees (p<0.0001). The flexion deformity cohort was treated with either skin grafts (8 patients) or flaps (9 patients) with a mean improvement of 44 degrees (p<0.0001). Skin grafts suffice for dorsal hand contractures to restore functional wrist ROM. For flexion contractures, flaps were more likely for contractures >6 months. Early release of burn contracture is advisable to avoid deep structure contracture.

  4. Measuring seeing with a Shack-Hartmann wave-front sensor during an active-optics experiment.

    PubMed

    Zhang, Yong; Yang, Dehua; Cui, Xiangqun

    2004-02-01

    We describe the measurement of atmospheric enclosure seeing along a 120-m light path by use of a Shack-Hartmann wave-front sensor (S-H WFS) for the first time to our knowledge in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) outdoor active-optics experiment system, based on the differential image motion method and a S-H WFS. Seeing estimates that were gained with the S-H WFS were analyzed and found to be in close agreement with the actual seeing conditions, the estimates of refractive-index structure constant, and the thin-mirror active optics results, which usually include the shape sensing precision and the active correction precision of the experimental system. Finally, some countermeasures against poor seeing conditions were considered and adopted.

  5. Use of polyurethane foam deformation sensor to record respiratory activity

    NASA Astrophysics Data System (ADS)

    Bredov, V. I.; Baranov, V. S.

    1980-05-01

    The sensor developed has some substantial advantages over other known types. It is highly sensitive over a wide range of strain loads. The level of the output signal is linearly related to the force exerted on it, and it is sufficient for direct recording without using amplifiers of electric signals. The sensor is based on elastic, spongy material, polyurethane foam (porolon) with current-conducting material on the pore surface, current-conducting carbon black or electrode paste. The elastic properties of the sensor are built in the actual base of the strain-sensitive element, which simplifies the construction substantially and increases the reliability of the unit. In order to test the possibility of using this sensor to examine respiratory function, human pneumograms were recorded with the subject in a calm state along with the respiratory activity of experimental animals (dogs). Samples of the respiratory curve are shown. The simplicity of design of the sensor makes it possible to use it in various physiological experiments.

  6. Deformation of the Calabrian Arc subduction complex and its relation to STEP activity at depth.

    NASA Astrophysics Data System (ADS)

    Polonia, Alina; Wortel, Rinus; Nijholt, Nicolai; Govers, Rob; Torelli, Luigi

    2015-04-01

    Propagating tear faults at the edge of subducted slabs ("Subduction transform edge propagator", STEP) are an intrinsic part of lithospheric plate dynamics. The surface expression of a STEP is generally not known yet, and is expected to vary significantly from one region to the other. We choose the Sicily -Calabria-Ionian Sea region, of which the lithosphere-upper mantle structure has the characteristics of a STEP zone, as a study area. The area has a very prominent accretionary wedge, the formation and subsequent deformation of which presumably were affected by the STEP activity at depth. In this contribution, we use seismic data on the near surface structure and deformation in combination with numerical model results to investigate the relation between deep STEP activity and near surface expression. Prominent features in the surface tectonics are the Malta escarpment (with predominantly normal faulting), the newly identified Ionian Fault and Alfeo-Etna fault system, and a distinct longitudinal division of the wedge into a western and an eastern lobe (Polonia et al., Tectonics, 2011). The two lobes are characterized by different structural style, deformation rates and basal detachment depths. Numerical model results indicate that the regional lithospheric structure, such as the orientation of the eastern passive (albeit subsequently activated) margin of Sicily relative to the Calabrian subduction zone, has a profound effect on possible fault activity along the Malta escarpment. Fault activity along the above primary fault structures may have varied in time, implying the possibility of intermittent activity. Interpreting seismicity in the context of a possible STEP, and the accompanying deformation zone at or near the surface, is not (yet) straightforward. Although direct evidence for recognizing all aspects of STEP activity is - as usual - lacking, a comparison with two well-known STEP regions, the northern part of the Tonga subduction zone and southern part of the

  7. Hydrodynamic Instabilities of Acid-Base Reaction Fronts: Active Role of a Color Indicator

    NASA Astrophysics Data System (ADS)

    Riolfo, L. A.; Almarcha, C.; Trevelyan, P. M. J.; El Hasi, C.; Zalts, A.; D'Onofrio, A.; de Wit, A.

    2010-11-01

    Chemical reactions are able to trigger hydrodynamic flows by, for example changing the density of the solutions across the reactive interfaces. In this work we present an experimental and theoretical study of the buoyancy-driven hydrodynamic instabilities that can occur when two miscible reactive solutions of an acid-base system are put in contact in the gravity field. We compare situations where a hydrochloric acid aqueous solution is put on top of a sodium hydroxide aqueous solution with or without a color indicator (Bromocresol Green). We also analyze the situation where a hydrochloric acid is put on top of an aqueous solution of a color indicator without any base. We show that the patterns observed and the instabilities taking place strongly depend on the presence of a color indicator. Using a reaction-diffusion model for the concentrations of all species (including the color indicator) we analyze the different possible sources of destabilization of the acid-base front and explain the various instabilities observed in each experimental system.

  8. Joint influence of transmural heterogeneities and wall deformation on cardiac bioelectrical activity: A simulation study.

    PubMed

    Colli Franzone, P; Pavarino, L F; Scacchi, S

    2016-10-01

    The aim of this work is to investigate, by means of numerical simulations, the influence of myocardial deformation due to muscle contraction and relaxation on the cardiac repolarization process in presence of transmural intrinsic action potential duration (APD) heterogeneities. The three-dimensional electromechanical model considered consists of the following four coupled components: the quasi-static transversely isotropic finite elasticity equations for the deformation of the cardiac tissue; the active tension model for the intracellular calcium dynamics and cross-bridge binding; the anisotropic Bidomain model for the electrical current flow through the deforming cardiac tissue; the membrane model of ventricular myocytes, including stretch-activated channels. The numerical simulations are based on our finite element parallel solver, which employs Multilevel Additive Schwarz preconditioners for the solution of the discretized Bidomain equations and Newton-Krylov methods for the solution of the discretized non-linear finite elasticity equations. Our findings show that: (i) the presence of intrinsic transmural cellular APD heterogeneities is not fully masked by electrotonic current flow or by the presence of the mechanical deformation; (ii) despite the presence of transmural APD heterogeneities, the recovery process follows the activation sequence and there is no significant transmural repolarization gradient; (iii) with or without transmural APD heterogeneities, epicardial electrograms always display the same wave shape and discordance between the polarity of QRS complex and T-wave; (iv) the main effects of the mechanical deformation are an increase of the dispersion of repolarization time and APD, when computed over the total cardiac domain and over the endo- and epicardial surfaces, while there is a slight decrease along the transmural direction. PMID:27545966

  9. A spiral wave front beacon for underwater navigation: basic concept and modeling.

    PubMed

    Hefner, Brian T; Dzikowicz, Benjamin R

    2011-06-01

    A spiral wave front source produces an acoustic field that has a phase that is proportional to the azimuthal angle about the source. The concept of a spiral wave front beacon is developed by combining this source with a reference source that has a phase that is constant with the angle. The phase difference between these sources contains information about the receiver's azimuthal angle relative to the beacon and can be used for underwater navigation. To produce the spiral wave front, two sources are considered: a "physical-spiral" source, which produces the appropriate phase by physically deforming the active element of the source into a spiral, and a "phased-spiral" source, which uses an array of active elements, each driven with the appropriate phase, to produce the spiral wave front. Using finite element techniques, the fields produced by these sources are examined in the context of the spiral wave front beacon, and the advantages of each source are discussed.

  10. In-use measurement of the activity, fuel use, and emissions of front-loader refuse trucks

    NASA Astrophysics Data System (ADS)

    Sandhu, Gurdas S.; Frey, H. Christopher; Bartelt-Hunt, Shannon; Jones, Elizabeth

    2014-08-01

    Field measurements were made for six front-loader refuse trucks for over 560 miles (901 km) and 47 h of operation using a portable emissions measurement system, electronic control unit data logger, and global positioning system receivers. Daily activity, fuel use rates, and emission rates are quantified in terms of operating mode bins defined by the U.S. Environmental Protection Agency for the MOVES emission factor model. On average, 44 (±4) percent of time was spent at idle, 5 (±1) percent braking or decelerating, 11 (±2) percent coasting, 23 (±3) percent cruising or accelerating at low speed (up to 25 mph, 40.2 kmph), 10 (±2) percent cruising or accelerating at moderate speed (25-50 mph, 40.2 to 80.4 kmph), and 7 (±3) percent cruising or accelerating at high speed (50 mph, 80.4 kmph or higher). Fuel use and emission rates varied among operating modes by factors of 6-24. The estimated daily activity cycle average fuel economy ranges from 2.3 to 3.2 mpg (0.98-1.4 kmpl). The PM emission rates for trucks with diesel particulate filters are 98 percent lower compared to those without. Variation in truck weight lead to differences in average fuel use and emission rates of 20 percent or less, except for hydrocarbons. The variation in the empirically-based daily activity cycle average rates were highly correlated with MOVES estimates, except for hydrocarbons. The data collected here are useful for quantifying daily activity specific to front-loaders, and for developing fuel use and emission estimates and models for this type of vehicle.

  11. Active deformation analysis and evaluation of earthquake hazard in Gafsa region (Southern Atlas of Tunisia)

    NASA Astrophysics Data System (ADS)

    Bahrouni, Nejib; Bouaziz, Samir; Soumaya, Abdelkader; Ben Ayed, Noureddine; Attafi, Khereddine

    2013-04-01

    The Southern Atlas of Tunisia constitutes the transition between Atlas fold and the Northern edge of the Saharan platform. The general direction is near to E-W deflected to N060 whose structural style and geometry of deformation still complex. This domain is Southern part of the seismic zone bordering the Northern African plate as indicated by the large seismic events that occurred periodically. The Gafsa area, more particularly concerned by seismic risk, is bordered to the North by the NW-SE trending "Gafsa Fault" and has significant seismic. The most active tectonic are related to the reactivating of pre-existing NW-SE and E-W trending strike-slip faulting. We will set up the network in the active zone of Gafsa surroundings, in order to cover the area of aftershocks (co-seismic surface rupture) of May 22, 1972 and December 27, 1985 (Ms=4.2) in Gafsa and November 7, 1989 (Ms=4.4) in Metlaoui, December 8, 2010 and in Sidi Aich (Ms=3.66). Paleostress and calculated focal mechanism solutions for the earthquakes show that the active stress field is a NW-SE trending compression. Damage and surface effects of land and urban areas caused by these events demonstrate the vulnerability of cities in the region of Gafsa to seismic activities. The analyses of recent and active deformation in this region has allowed the assessment of urban seismic hazard and take stock seismic zones embedded in a distorted geographic information system (GIS) in close relationship with the regional tectonic setting. This assessment has provided crucial information on the neotectonic deformation and seismotectonics of Gafsa region and its surrounding which affects remote orogenic dynamics and the current state of the North African margin. In particular, the comparison between the deformations and quantified seismic activity has also assessed the risk and the regional seismic hazard and develop a seismotectonic zoning.

  12. Evidence of ongoing crustal deformation related to magmatic activity near Socorro, New Mexico

    NASA Technical Reports Server (NTRS)

    Larsen, S.; Brown, L.; Reilinger, R.

    1986-01-01

    Leveling measurements conducted in 1980-1981 by the National Geodetic Survey in the Socorro area of the Rio Grande rift are analyzed. Crustal uplift related to magma inflation in the midcrustal magma body is detected; an uplift of 0.18 cm/yr is measured for the time between 1951-1980. The survey data of 1911 and 1959 are compared to the present data and good correlation is observed. The systematic leveling errors including height-dependence and refraction errors are studied. The 30-km-wide subsidence in the area is examined. The spatial correlation between seismic activity, the Socorro magma body, and crustal deformation in Socorro is investigated. The crustal movement from magma reservior activities is modeled using the formulations of Dieterich and Decker (1975). The modeling of the deformation reveals that the movement in the Socorro area is associated with the 19-km deep Socorro magma body.

  13. Isolating active orogenic wedge deformation in the southern Subandes of Bolivia

    NASA Astrophysics Data System (ADS)

    Weiss, Jonathan R.; Brooks, Benjamin A.; Foster, James H.; Bevis, Michael; Echalar, Arturo; Caccamise, Dana; Heck, Jacob; Kendrick, Eric; Ahlgren, Kevin; Raleigh, David; Smalley, Robert; Vergani, Gustavo

    2016-08-01

    A new GPS-derived surface velocity field for the central Andean backarc permits an assessment of orogenic wedge deformation across the southern Subandes of Bolivia, where recent studies suggest that great earthquakes (>Mw 8) are possible. We find that the backarc is not isolated from the main plate boundary seismic cycle. Rather, signals from subduction zone earthquakes contaminate the velocity field at distances greater than 800 km from the Chile trench. Two new wedge-crossing velocity profiles, corrected for seasonal and earthquake affects, reveal distinct regions that reflect (1) locking of the main plate boundary across the high Andes, (2) the location of and loading rate at the back of orogenic wedge, and (3) an east flank velocity gradient indicative of décollement locking beneath the Subandes. Modeling of the Subandean portions of the profiles indicates along-strike variations in the décollement locked width (WL) and wedge loading rate; the northern wedge décollement has a WL of ~100 km while accumulating slip at a rate of ~14 mm/yr, whereas the southern wedge has a WL of ~61 km and a slip rate of ~7 mm/yr. When compared to Quaternary estimates of geologic shortening and evidence for Holocene internal wedge deformation, the new GPS-derived wedge loading rates may indicate that the southern wedge is experiencing a phase of thickening via reactivation of preexisting internal structures. In contrast, we suspect that the northern wedge is undergoing an accretion or widening phase primarily via slip on relatively young thrust-front faults.

  14. Comparative analysis of active drag using the MAD system and an assisted towing method in front crawl swimming.

    PubMed

    Formosa, Daniel P; Toussaint, Huub M; Mason, Bruce R; Burkett, Brendan

    2012-12-01

    The measurement of active drag in swimming is a biomechanical challenge. This research compared two systems: (i) measuring active drag (MAD) and (ii) assisted towing method (ATM). Nine intermediate-level swimmers (19.7 ± 4.4 years) completed front crawl trials with both systems during one session. The mean (95% confidence interval) active drag for the two systems, at the same maximum speed of 1.68 m/s (1.40-1.87 m/s), was significantly different (p = .002) with a 55% variation in magnitude. The mean active drag was 82.3 N (74.0-90.6 N) for the MAD system and 148.3 N (127.5-169.1 N) for the ATM system. These differences were attributed to variations in swimming style within each measurement system. The inability to measure the early catch phase and kick, along with the fixed length and depth hand place requirement within the MAD system generated a different swimming technique, when compared with the more natural free swimming ATM protocol. A benefit of the MAD system was the measurement of active drag at various speeds. Conversely, the fixed towing speed of the ATM system allowed a natural self-selected arm stroke (plus kick) and the generation of an instantaneous force-time profile.

  15. Monitoring Hippocampus Electrical Activity In Vitro on an Elastically Deformable Microelectrode Array

    PubMed Central

    Yu, Zhe; Graudejus, Oliver; Tsay, Candice; Lacour, Stéphanie P.; Wagner, Sigurd

    2009-01-01

    Abstract Interfacing electronics and recording electrophysiological activity in mechanically active biological tissues is challenging. This challenge extends to recording neural function of brain tissue in the setting of traumatic brain injury (TBI), which is caused by rapid (within hundreds of milliseconds) and large (greater than 5% strain) brain deformation. Interfacing electrodes must be biocompatible on multiple levels and should deform with the tissue to prevent additional mechanical damage. We describe an elastically stretchable microelectrode array (SMEA) that is capable of undergoing large, biaxial, 2-D stretch while remaining functional. The new SMEA consists of elastically stretchable thin metal films on a silicone membrane. It can stimulate and detect electrical activity from cultured brain tissue (hippocampal slices), before, during, and after large biaxial deformation. We have incorporated the SMEA into a well-characterized in vitro TBI research platform, which reproduces the biomechanics of TBI by stretching the SMEA and the adherent brain slice culture. Mechanical injury parameters, such as strain and strain rate, can be precisely controlled to generate specific levels of damage. The SMEA allowed for quantification of neuronal function both before and after injury, without breaking culture sterility or repositioning the electrodes for the injury event, thus enabling serial and long-term measurements. We report tests of the SMEA and an initial application to study the effect of mechanical stimuli on neuron function, which could be employed as a high-content, drug-screening platform for TBI. PMID:19594385

  16. A review about the mechanisms associated with active deformation, regional uplift and subsidence in southern South America

    NASA Astrophysics Data System (ADS)

    Folguera, Andrés; Gianni, Guido; Sagripanti, Lucía; Rojas Vera, Emilio; Novara, Iván; Colavitto, Bruno; Alvarez, Orlando; Orts, Darío; Tobal, Jonathan; Giménez, Mario; Introcaso, Antonio; Ruiz, Francisco; Martínez, Patricia; Ramos, Victor A.

    2015-12-01

    A broad range of processes acted simultaneously during the Quaternary producing relief in the Andes and adjacent foreland, from the Chilean coast, where the Pacific Ocean floor is being subducted beneath South American, to the Brazilian and the Argentinean Atlantic platform area. This picture shows to be complex and responds to a variety of processes. The Geoid exemplifies this spectrum of uplift mechanisms, since it reflects an important change at 35°S along the Andes and the foreland that could be indicating the presence of dynamic forces modeling the topography with varying intensity through the subduction margin. On the other hand, mountains uplifted in the Atlantic margin, along a vast sector of the Brazilian Atlantic coast and inland regions seem to be created at the area where the passive margin has been hyper-extended and consequently mechanically debilitated and the forearc region shifts eastwardly at a similar rate than the westward advancing continent. Therefore the forearc at the Arica latitudes can be considered as relatively stationary and dynamically sustained by a perpendicular-to-the-margin asthenospheric flow that inhibits trench roll back, determining a highly active orogenic setting at the eastern Andes in the Subandean region. To the south, the Pampean flat subduction zone creates particular conditions for deformation and rapid propagation of the orogenic front producing a high-amplitude orogen. In the southern Central and Patagonian Andes, mountain (orogenic) building processes are attenuated, becoming dominant other mechanisms of exhumation such as the i) impact of mantle plumes originated in the 660 km mantle transition, ii) the ice-masse retreat from the Andes after the Pleistocene producing an isostatic rebound, iii) the dynamic topography associated with the opening of an asthenospheric window during the subduction of the Chile ridge and slab tearing processes, iv) the subduction of oceanic swells linked to transform zones and v) the

  17. Interseismic deformations along Ecuador active fault systems: Contribution of space-borne SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Champenois, J.; Audin, L.; Baize, S.; Nocquet, J.; Alvarado, A.

    2013-05-01

    Located in the Northern Andes along the active subduction zone of the Nazca plate beneath the South American continent, Ecuador is highly exposed to seismic hazard. Up to now, numerous multidisciplinary studies for the last ten years focused on the seismicity related to the subduction, whereas few investigations concentrated on the crustal seismicity in the upper plate (through few strong events like the 1797 Riobamba earthquake, ML 8.3, 12.000 deaths). The faults that are responsible of these earthquakes are poorly known in term of slip rate and in some cases are even not identified yet. To address this issue and compare the interseismic data to the geomorphological long term signature of active faulting we propose to use multi-temporal Synthetic Aperture Radar Interferometry (InSAR) methods.Using these cost-effective techniques, we are able to investigate surface interseismic deformation with an unprecedented spatial density of measurements (highly superior to Global Positioning System network density). This study presents preliminary results of tectonic surface deformation using ERS (1993-2000) and Envisat (2002-2010) SAR data in the Inter Andean Valley and along the eastern border of the North Andean Block, where is accommodated the relative displacement between the North Andean Block and South America plate (~ 8 mm/yr). We generated average velocity maps and consistent time-series of displacements with values measured along the line of sight of the radar. Resulting maps of ground displacements are calibrated by GPS data in order to provide a homogeneous database. These preliminary results show large scale deformation localized on some major fault systems in the Inter Andean Valley (from Quito to north of Cuenca) and allow an updating of the active faults map. Moreover, these InSAR results permit detecting and quantifying ground deformation due to volcanic unrest.

  18. Comparison of epicardial deformation in passive and active isolated rabbit hearts

    NASA Astrophysics Data System (ADS)

    Ho, Andrew; Tang, Liang; Chiang, Fu-Pen; Lin, Shien-Fong

    2007-02-01

    Mechanical deformation of isolated rabbit hearts through passive inflation techniques have been a viable form of replicating heart motion, but its relation to the heart's natural active contractions remain unclear. The mechanical properties of the myocardium may show diverse characteristics while in tension and compression. In this study, epicardial strain was measured with the assistance of computer-aided speckle interferometry (CASI)1. CASI tracks the movement of clusters of particles for measuring epicardial deformation. The heart was cannulated and perfused with Tyrode's solution. Silicon carbide particles were applied onto the myocardium to form random speckle pattern images while the heart was allowed to actively contract and stabilize. High resolution videos (1000x1000 pixels) of the left ventricle were taken with a complementary metal oxide semiconductor (CMOS) camera as the heart was actively contracting through electrical pacing at various cycle lengths between 250-800 ms. A latex balloon was then inserted into the left ventricle via left atrium and videos were taken as the balloon was repeatedly inflated and deflated at controlled volumes (1-3 ml/cycle). The videos were broken down into frames and analyzed through CASI. Active contractions resulted in non-uniform circular epicardial and uniaxial contractions at different stages of the motion. In contrast, the passive heart demonstrated very uniform expansion and contraction originating from the source of the latex balloon. The motion of the active heart caused variations in deformation, but in comparison to the passive heart, had a more enigmatic displacement field. The active heart demonstrated areas of large displacement and others with relatively no displacement. Application of CASI was able to successfully distinguish the motions between the active and passive hearts.

  19. Projection Moire Interferometry for Rotorcraft Applications: Deformation Measurements of Active Twist Rotor Blades

    NASA Technical Reports Server (NTRS)

    Fleming, Gary A.; Soto, Hector L.; South, Bruce W.

    2002-01-01

    Projection Moire Interferometry (PMI) has been used during wind tunnel tests to obtain azimuthally dependent blade bending and twist measurements for a 4-bladed Active Twist Rotor (ATR) system in simulated forward flight. The ATR concept offers a means to reduce rotor vibratory loads and noise by using piezoelectric active fiber composite actuators embedded in the blade structure to twist each blade as they rotate throughout the rotor azimuth. The twist imparted on the blades for blade control causes significant changes in blade loading, resulting in complex blade deformation consisting of coupled bending and twist. Measurement of this blade deformation is critical in understanding the overall behavior of the ATR system and the physical mechanisms causing the reduction in rotor loads and noise. PMI is a non-contacting, video-based optical measurement technique capable of obtaining spatially continuous structural deformation measurements over the entire object surface within the PMI system field-of-view. When applied to rotorcraft testing, PMI can be used to measure the azimuth-dependent blade bending and twist along the full span of the rotor blade. This paper presents the PMI technique as applied to rotorcraft testing, and provides results obtained during the ATR tests demonstrating the PMI system performance. PMI measurements acquired at select blade actuation conditions generating minimum and maximum rotor loads are provided to explore the interrelationship between rotor loads, blade bending, and twist.

  20. On interrelation between seismic activity and the Earth crust deformations of Vrancea zone

    NASA Astrophysics Data System (ADS)

    Dultsev, A.; Pronyshyn, R.; Siejka, Z.; Serant, O.; Tretyak, K.; Zablotskyj, F.

    2009-04-01

    An investigated territory covers the whole seismically active zone of Vrancea mountains (Romania). It is located between 43° and 47° parallels in latitude and 23° and 29° meridians in longitude. The weekly solutions of coordinates of six permanent stations (BACA, BAIA, BUCU, COST, DEVA, IGEO) allocated on the territories of Romania and Moldova have been used as the initial data for carrying out of the investigations. These initial data were obtained during 2007-2008. The results of determination of the earthquake parameters (coordinates, focal depth, magnitude and energy) have been obtained from a network of seismic stations. An analysis of the temporal earthquake distribution in 2007-2008 showed the alternation of the periods of seismic activity and its absence. The duration of these periods ranges from one to three weeks. The Earth crust deformation parameters between the recurrent periods of seismic activity and its absence have been calculated on basis of weekly solutions for the territory bounded by GPS-permanent stations. The accumulative values of the earthquake energy and magnitude were calculated for the periods of seismic activity. It had been ascertained that the territory of Vrancea zone undergoes the permanent stretching into northeast and southwest directions as well as the compressing into northwest and southeast ones. In fact, the more fast attenuation of the seismic waves occurs in the direction of the contraction axis and the slowest attenuation of ones occurs in the direction of the axis of elongation. The parameters of total amplitude and earthquake energy in the periods of seismic activity have high-degree correlation with difference of the deformations of next periods of seismic activity and its absence. It enables to predict a change of the deformation increment in the zone of earthquake focuses of Vrancea territory by means of the earthquake total force.

  1. Active faults in the deformation zone off Noto Peninsula, Japan, revealed by high- resolution seismic profiles

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Okamura, Y.; Murakami, F.; Kimura, H.; Ikehara, K.

    2008-12-01

    Recently, a lot of earthquakes occur in Japan. The deformation zone which many faults and folds have concentrated exists on the Japan Sea side of Japan. The 2007 Noto Hanto Earthquake (MJMA 6.9) and 2007 Chuetsu-oki Earthquake (MJMA 6.8) were caused by activity of parts of faults in this deformation zone. The Noto Hanto Earthquake occurred on 25 March, 2007 under the northwestern coast of Noto Peninsula, Ishikawa Prefecture, Japan. This earthquake is located in Quaternary deformation zone that is continued from northern margin of Noto Peninsula to southeast direction (Okamura, 2007a). National Institute of Advanced Industrial Science and Technology (AIST) carried out high-resolution seismic survey using Boomer and 12 channels short streamer cable in the northern part off Noto Peninsula, in order to clarify distribution and activities of active faults in the deformation zone. A twelve channels short streamer cable with 2.5 meter channel spacing developed by AIST and private corporation is designed to get high resolution seismic profiles in shallow sea area. The multi-channel system is possible to equip on a small fishing boat, because the data acquisition system is based on PC and the length of the cable is short and easy to handle. Moreover, because the channel spacing is short, this cable is very effective for a high- resolution seismic profiling survey in the shallow sea, and seismic data obtained by multi-channel cable can be improved by velocity analysis and CDP stack. In the northern part off Noto Peninsula, seismic profiles depicting geologic structure up to 100 meters deep under sea floor were obtained. The most remarkable reflection surface recognized in the seismic profiles is erosion surface at the Last Glacial Maximum (LGM). In the western part, sediments about 30 meters (40 msec) thick cover the erosional surface that is distributed under the shelf shallower than 100m in depth and the sediments thin toward offshore and east. Flexures like deformation in

  2. The surface geometry of inherited joint and fracture trace patterns resulting from active and passive deformation

    NASA Technical Reports Server (NTRS)

    Podwysocki, M. H.; Gold, D. P.

    1974-01-01

    Hypothetical models are considered for detecting subsurface structure from the fracture or joint pattern, which may be influenced by the structure and propagated to the surface. Various patterns of an initially orthogonal fracture grid are modeled according to active and passive deformation mechanisms. In the active periclinal structure with a vertical axis, fracture frequency increased both over the dome and basin, and remained constant with decreasing depth to the structure. For passive periclinal features such as a reef or sand body, fracture frequency is determined by the arc of curvature and showed a reduction over the reefmound and increased over the basin.

  3. Removal of daytime thermal deformations in the GBT active surface via out-of-focus holography

    NASA Astrophysics Data System (ADS)

    Hunter, T. R.; Mello, M.; Nikolic, B.; Mason, B. S.; Schwab, F. R.; Ghigo, F. D.; Dicker, S. R.

    2009-01-01

    The 100-m diameter Green Bank Telescope (GBT) was built with an active surface of 2209 actuators in order to achieve and maintain an accurate paraboloidal shape. While much of the large-scale gravitational deformation of the surface can be described by a finite element model, a significant uncompensated gravitational deformation exists. In recent years, the elevation-dependence of this residual deformation has been successfully measured during benign nighttime conditions using the out-of-focus (OOF) holography technique (Nikolic et al, 2007, A&A 465, 685). Parametrized by a set of Zernike polynomials, the OOF model correction was implemented into the active surface and has been applied during all high frequency observations since Fall 2006, yielding a consistent gain curve that is constant with elevation. However, large-scale thermal deformation of the surface has remained a problem for daytime high-frequency observations. OOF holography maps taken throughout a clear winter day indicate that surface deformations become significant whenever the Sun is above 10 degrees elevation, but that they change slowly while tracking a single source. In this paper, we describe a further improvement to the GBT active surface that allows an observer to measure and compensate for the thermal surface deformation using the OOF technique. In order to support high-frequency observers, "AutoOOF" is a new GBT Astrid procedure that acquires a quick set of in-focus and out-of-focus on-the-fly continuum maps on a quasar using the currently active receiver. Upon completion of the maps, the data analysis software is launched automatically which produces and displays the surface map along with a set of Zernike coefficients. These coefficients are then sent to the active surface manager which combines them with the existing gravitational Zernike terms and FEM in order to compute the total active surface correction. The end-to-end functionality has been tested on the sky at Q-Band and Ka

  4. Deformation across the seismic cycle in tectonically active regions: Imaging, modeling, and interpretations

    NASA Astrophysics Data System (ADS)

    Barnhart, William Douglas

    Images of surface displacements in response to tectonic forces can provide independent, spatially dense observations that assist in understanding sub-surface processes. When considered independently or augmented with more traditional observations of active tectonics such as seismicity and ground mapping, these measurements provide constraints on spatially and temporally variable fault behavior across the seismic cycle. Models of fault behavior inferred from these observations in turn allow us to address topics in geologic hazards assessment, the long- and short-term character of strain in deforming regions, and the interactions between faults throughout the crust. In this dissertation, I use remotely sensed observations of ground displacements from interferometric synthetic aperture radar (InSAR) to approach several problems related to earthquake and aseismic fault slip. I establish image processing and inverse methods for better detailing subsurface fault slip and apply these to the 2010-2011 Canterbury, New Zealand sequence. Then, I focus on the active tectonics of the Zagros Mountains in southern Iran. There, I show through orogen-wide InSAR time series analysis that active strain is accommodated across the width of the mountain belt. I also use a combination of InSAR, local seismicity, and structural modeling to demonstrate that strain is vertically partitioned within the Zagros fold-and-thrust belt, with earthquakes controlling deformation in the underlying basement while the overlying sedimentary section shortens in transient, earthquake-triggered aseismic slip events. In certain examples, these aseismic slip events directly contribute to the growth of fault-bend folds. I use these inferences to explore a previously noted discrepancy between observed shortening and that which is expected from known earthquakes. I show that the earthquakes and short-term aseismic slip cannot account for this discrepancy, and that additional deformation mechanisms must be

  5. Failure and deformation mechanisms at macro- and nano-scales of alkali activated clay

    NASA Astrophysics Data System (ADS)

    Sekhar Das, Pradip; Bhattacharya, Manjima; Chanda, Dipak Kr; Dalui, Srikanta; Acharya, Saikat; Ghosh, Swapankumar; Mukhopadhyay, Anoop Kumar

    2016-06-01

    Here we report two qualitative models on failure and deformation mechanisms at macro- and nano-scales of alkali activated clay (AACL), a material of extraordinary importance as a low cost building material. The models were based on experimental data of compressive failure and nanoindentation response of the AACL materials. A 420% improvement in compressive strength (σ c) of the AACL was achieved after 28 days (d) of curing at room temperature and it correlated well with the decrements in the residual alkali and pH concentrations with the increase in curing time. Based on extensive post-mortem FE-SEM examinations, a schematic model for the compressive failure mechanism of AACL was proposed. In addition, the nanoindentation results of AACL provided the first ever experimental evidence of the presence of nano-scale plasticity and a nano-scale contact deformation resistance that increased with the applied load. These results meant the development of a unique strain tolerant microstructure in the AACL of Indian origin. The implications of these new observations were discussed in terms of a qualitative model based on the deformation of layered clay structure.

  6. Assessment of Tungsten Content on Tertiary Creep Deformation Behavior of Reduced Activation Ferritic-Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Vanaja, J.; Laha, Kinkar

    2015-10-01

    Tertiary creep deformation behavior of reduced activation ferritic-martensitic (RAFM) steels having different tungsten contents has been assessed. Creep tests were carried out at 823 K (550 °C) over a stress range of 180 to 260 MPa on three heats of the RAFM steel (9Cr-W-0.06Ta-0.22V) with tungsten content of 1, 1.4, and 2.0 wt pct. With creep exposure, the steels exhibited minimum in creep rate followed by progressive increase in creep rate until fracture. The minimum creep rate decreased, rupture life increased, and the onset of tertiary stage of creep deformation delayed with the increase in tungsten content. The tertiary creep behavior has been assessed based on the relationship, , considering minimum creep rate () instead of steady-state creep rate. The increase in tungsten content was found to decrease the rate of acceleration of tertiary parameter ` p.' The relationships between (1) tertiary parameter `p' with minimum creep rate and time spent in tertiary creep deformation and (2) the final creep rate with minimum creep rate revealed that the same first-order reaction rate theory prevailed in the minimum creep rate as well as throughout the tertiary creep deformation behavior of the steel. A master tertiary creep curve of the steels has been developed. Scanning electron microscopic investigation revealed enhanced coarsening resistance of carbides in the steel on creep exposure with increase in tungsten content. The decrease in tertiary parameter ` p' with tungsten content with the consequent decrease in minimum creep rate and increase in rupture life has been attributed to the enhanced microstructural stability of the steel.

  7. Adenosine: front and center in linking nutrition and metabolism to neuronal activity

    PubMed Central

    Greene, Robert W.

    2011-01-01

    Many individuals with epilepsy benefit from consuming a ketogenic diet, which is similar to the more commonly known Atkins diet. The underlying molecular reason for this has not been determined. However, in this issue of the JCI, Masino et al. have elucidated the mechanism responsible for the antiepileptic effects of the ketogenic diet in mice. The diet is shown to decrease expression of the enzyme adenosine kinase (Adk), which is responsible for clearing the endogenous antiepileptic agent adenosine (Ado) from the extracellular CNS space. Decreased expression of Adk results in increased extracellular Ado, activation of inhibitory Ado A1 receptors, and decreased seizure generation, the desired therapeutic effect. The authors’ work serves to emphasize the importance of controlling Adk expression, not only as the mechanism of action of the ketogenic diet, but also as a potential target of future therapies. PMID:21701073

  8. A hybrid active optical system for wave front preservation and variable focal distance

    NASA Astrophysics Data System (ADS)

    Cocco, Daniele; Bortoletto, Gianluca; Sergo, Rudi; Sostero, Giovanni; Cudin, Ivan

    2010-05-01

    A new Free Electron Laser (FEL) user facility, named FERMI@Elettra, is under construction at Sincrotrone Trieste (Italy). It is based on a seeded scheme to provide an almost perfect transform limited beam with fully spatial coherence. The wavelength range will be 100-3 nm with fundamental and will go down to 1 nm by using higher harmonics. It will be operative by autumn 2010. The exceptional characteristics of the source must be preserved until the experimental chamber, where a large set of different experiments will be performed. This condition poses very tight requirements to the design of the beamlines and, in particular, to the focusing optics. Here we will present the active optics system developed for Fermi but intended to be used also on the Elettra beamlines. It is based on the adoption of a hybrid active system composed by UHV compatible stepping motors and piezo ceramic actuators. These mirrors are supposed to provide focal distances from 0.8 m to infinity with an angle of incidence up to a few degrees and residual shape errors below 10 or 5 nm (depending on the wavelength). In this way it is possible to work with an almost perfect focused coherent beam as well as with a uniform defocused or unfocused image. The metrology results on the first 400 mm long mirror will be shown and the actuator system described. A strain gauge assembly, calibrated in Elettra by means of a long trace profiler, and controlled by a custom made electronic system developed by us, is used as a direct in situ encoder.

  9. Active deformation in the northern Sierra de Valle Fértil, Sierras Pampeanas, Argentina

    NASA Astrophysics Data System (ADS)

    Ortiz, Gustavo; Alvarado, Patricia; Fosdick, Julie C.; Perucca, Laura; Saez, Mauro; Venerdini, Agostina

    2015-12-01

    The Western Sierras Pampeanas region in the San Juan Province is characterized by thick-skinned deformation with approximately N-S trending ranges of average heights of 2500 m and a high frequency occurrence of seismic activity. Its location to the east of the mainly thin-skinned tectonics of the Argentine Precordillera fold-and-thrust belt suggests that at 30°S, deformation is concentrated in a narrow zone involving these two morphostructural units. In this paper, we present new apatite (U-Th)/He results (AHe) across the northern part of the Sierra de Valle Fértil (around 30°S) and analyze them in a framework of thermochronologic available datasets. We found Pliocene AHe results for Carboniferous and Triassic strata in the northern Sierra de Valle Fértil consistent with the hypothesis of recent cooling and inferred erosional denudation concentrated along the northern end of this mountain range. Our analysis shows that this northern region may have evolved under different conditions than the central part of the Sierra de Valle Fértil. Previous studies have observed AHe ages consistent with Permian through Cretaceous cooling, indicating the middle part of the Sierra de Valle Fértil remained near surface before the Pampean slab subduction flattening process. Those studies also obtained ˜5 My cooling ages in the southern part of the Sierra de Valle Fértil, which are similar to our results in the northern end of the range. Taken together, these results suggest a pattern of young deformation in the northern and southern low elevation ends of the Sierra de Valle Fértil consistent with regions of high seismic activity, and Quaternary active faulting along the western-bounding thrust fault of the Sierra de Valle Fértil.

  10. GPS constraints on active deformation in the Isparta Angle region of SW Turkey

    NASA Astrophysics Data System (ADS)

    Tiryakioğlu, İbrahim; Floyd, Michael; Erdoğan, Saffet; Gülal, Engin; Ergintav, Semih; McClusky, Simon; Reilinger, Robert

    2013-12-01

    We use survey and continuous GPS observations during the period 1997-2010 to investigate active deformation in the Isparta Angle region of SW Anatolia, Turkey. This region, bordered by the Fethiye Burdur Fault Zone (FBFZ) in the west and the SE extension of the Aksehir Simav Fault Zone (AKSFZ) in the east, accommodates a part of the active deformation of W Turkey. Our results show that the Isparta Angle region rotates counter-clockwise (CCW) with respect to Anatolia. Both the FBFZ and the AKSFZ are predominantly transtensional boundaries that accommodate southward motion of the Isparta region with respect to Anatolia. The FBFZ has left-lateral strike-slip behaviour along its SW segment that changes to right-lateral strike-slip along its NE extension. This change in the sense of strike-slip motion is accommodated by extension on a NW-SE striking normal fault system that is associated with the Menderes Graben system. Transtensional fault systems along the boundaries of the Isparta Angle with Anatolia are inconsistent with extrusion models for present-day southward motion. An increase in motion rates towards the Hellenic and Cyprus arc subduction systems, and CCW of the Isparta region, supports dynamic models involving active rollback of the subducting African Plate, toroidal mantle flow around the eastern edge of the subducting African slab near the Hellenic arc/Florence Rise junction, and/or gravitational collapse of the overriding Anatolia Plate.

  11. Attenuation Properties of Fontainebleau Sandstone During True-Triaxial Deformation using Active and Passive Ultrasonics

    NASA Astrophysics Data System (ADS)

    Goodfellow, S. D.; Tisato, N.; Ghofranitabari, M.; Nasseri, M. H. B.; Young, R. P.

    2015-11-01

    Active and passive ultrasonic methods were used to study the evolution of attenuation properties in a sample of Fontainebleau sandstone during true-triaxial deformation. A cubic sample of Fontainebleau sandstone (80 mm × 80 mm × 80 mm) was deformed under true-triaxial stresses until failure. From the stress state: σ _3 = 5 MPa and σ _1 = σ _2 = 35 MPa, σ _1 was increased at a constant displacement rate until the specimen failed. Acoustic emission (AE) activity was monitored by 18 piezoelectric sensors and bandpass filtered between 100 kHz and 1 MHz. A source location analysis was performed on discrete AE data harvested from the continuous record where 48,502 events were locatable inside the sample volume. AE sensors were sequentially pulsed during periodic P-wave surveys among 135 raypaths. Analytical solutions for Biot, squirt flow, viscous shear, and scattering attenuation were used to discuss to observed attenuation at various stages of the experiment. We concluded that initial attenuation anisotropy was stress induced and resulted from friction and squirt flow. Later attenuation of the high-frequency spectrum was attributed to scattering as a result of the formation of large macroscopic vertical fractures. Passive (AE) ultrasonic data produced similar information to that from active data but with enhanced temporal and spacial resolution.

  12. Distribution of deformation on an active normal fault network, NW Corinth Rift

    NASA Astrophysics Data System (ADS)

    Ford, Mary; Meyer, Nicolas; Boiselet, Aurélien; Lambotte, Sophie; Scotti, Oona; Lyon-Caen, Hélène; Briole, Pierre; Caumon, Guillaume; Bernard, Pascal

    2013-04-01

    Over the last 20-25 years, geodetic measurements across the Gulf of Corinth have recorded high extension rates varying from 1.1 cm/a in the east to a maximum of 1.6 cm/a in the west. Geodetic studies also show that current deformation is confined between two relatively rigid blocks defined as Central Greece (to the north) and the Peloponnesus to the south. Active north dipping faults (<1 Ma) define the south coast of the subsiding Gulf, while high seismicity (major earthquakes and micro-seismicity) is concentrated at depth below and to the north of the westernmost Gulf. How is this intense deformation distributed in the upper crust? Our objectives here are (1) to propose two models for the distribution of deformation in the upper crust in the westernmost rift since 1 Ma, and (2) to place the tectonic behaviour of the western Gulf in the context of longer term rift evolution. Over 20 major active normal faults have been identified in the CRL area based specific characteristics (capable of generating earthquakes M> 5.5, active in the last 1 M yrs, slip rate >0.5 mm/a). Because of the uncertainty related to fault geometry at depth two models for 3D fault network geometry in the western rift down to 10 km were constructed using all available geophysical and geological data. The first model assumes planar fault geometries while the second uses listric geometries for major faults. A model for the distribution of geodetically-defined extension on faults is constructed along five NNE-SSW cross sections using a variety of data and timescales. We assume that the role of smaller faults in accommodating deformation is negligible so that extension is fully accommodated on the identified major faults. Uncertainties and implications are discussed. These models provide estimates of slip rate for each fault that can be used in seismic hazard models. A compilation of onshore and offshore data shows that the western Gulf is the youngest part of the Corinth rift having initiated

  13. Integrated chassis control of active front steering and yaw stability control based on improved inverse nyquist array method.

    PubMed

    Zhu, Bing; Chen, Yizhou; Zhao, Jian

    2014-01-01

    An integrated chassis control (ICC) system with active front steering (AFS) and yaw stability control (YSC) is introduced in this paper. The proposed ICC algorithm uses the improved Inverse Nyquist Array (INA) method based on a 2-degree-of-freedom (DOF) planar vehicle reference model to decouple the plant dynamics under different frequency bands, and the change of velocity and cornering stiffness were considered to calculate the analytical solution in the precompensator design so that the INA based algorithm runs well and fast on the nonlinear vehicle system. The stability of the system is guaranteed by dynamic compensator together with a proposed PI feedback controller. After the response analysis of the system on frequency domain and time domain, simulations under step steering maneuver were carried out using a 2-DOF vehicle model and a 14-DOF vehicle model by Matlab/Simulink. The results show that the system is decoupled and the vehicle handling and stability performance are significantly improved by the proposed method.

  14. Integrated Chassis Control of Active Front Steering and Yaw Stability Control Based on Improved Inverse Nyquist Array Method

    PubMed Central

    2014-01-01

    An integrated chassis control (ICC) system with active front steering (AFS) and yaw stability control (YSC) is introduced in this paper. The proposed ICC algorithm uses the improved Inverse Nyquist Array (INA) method based on a 2-degree-of-freedom (DOF) planar vehicle reference model to decouple the plant dynamics under different frequency bands, and the change of velocity and cornering stiffness were considered to calculate the analytical solution in the precompensator design so that the INA based algorithm runs well and fast on the nonlinear vehicle system. The stability of the system is guaranteed by dynamic compensator together with a proposed PI feedback controller. After the response analysis of the system on frequency domain and time domain, simulations under step steering maneuver were carried out using a 2-DOF vehicle model and a 14-DOF vehicle model by Matlab/Simulink. The results show that the system is decoupled and the vehicle handling and stability performance are significantly improved by the proposed method. PMID:24782676

  15. Investigation of the Deformation Activation Volume of an Ultrafinegrained Ti50Ni50 Alloy

    NASA Astrophysics Data System (ADS)

    Gunderov, D. V.; Churakova, A. A.; Lukianov, A. V.; Prokofiev, E. A.; Prokoshkin, S. D.; Kreizberg, A. Yu.; Raab, G. I.; Sabirov, I. N.

    2015-10-01

    The mechanical properties, strain rate sensitivity (m) and deformation activation volume (ΔV) are investigated at the experimental temperatures from 20 to 400°C in a Ti50Ni50 alloy in a coarse-grained (CG) state with the austenite grain size D = 200 μm and in an ultrafine-grained (UFG) state with D = 700 μm following an ECAP treatment. It is observed that this treatment improves the yield strength of the alloy compared to its CG-state. The strain rate sensitivity, m, is found to be by a factor of 1.5-2 higher than that of CG-specimens; it increases with the temperature in both states of the material. As the temperature of the material in tension increases up to Т = 150-250°C, parameter ΔV increases to its maximum and with a further growth of the experimental temperature to 400°C, parameter ΔV decreases. The deformation activation volume of the alloy in the UFG-state is by a factor of 2-4 larger than that in the CG-state for the same experimental temperatures.

  16. Active salt deformation and rapid, transient incision along the Colorado River near Moab, Utah

    NASA Astrophysics Data System (ADS)

    Jochems, Andrew P.; Pederson, Joel L.

    2015-04-01

    In certain settings, erosion is driven by and balanced with tectonic uplift, but the evolution of many landscapes is dominated by other factors such as geologic substrate, drainage history, and transient incision. The Colorado Plateau is an example where these controls are debated and where salt deformation is hypothesized to be locally active and driven by differential unloading, although this is unconfirmed and unquantified in most places. We use luminescence-dated Colorado River terraces upstream of Moab, Utah, to quantify rates of salt-driven subsidence and uplift at the local scale. Active deformation in the study area is also supported by patterns of concavity along tributary drainages crossing salt structures. Subsidence in Professor Valley at a time-averaged rate of ~500 m/Myr (meters/million years) is superimposed upon rapid bedrock incision rates that increase from ~600 to ~900 m/Myr upstream through the study area. Such high rates are unexpected given the absence of sources of regional tectonic uplift here. Instead, the incision rate pattern across the greater area is consistent with a transient signal, perhaps still from ancient drainage integration through Grand Canyon far downstream, and then amplified by unloading at both the broad regional scale and at the local canyon scale.

  17. Cloud Front

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02171 Cloud Front

    These clouds formed in the south polar region. The faintness of the cloud system likely indicates that these are mainly ice clouds, with relatively little dust content.

    Image information: VIS instrument. Latitude -86.7N, Longitude 212.3E. 17 meter/pixel resolution.

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

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

  18. The structure of mountain fronts

    NASA Astrophysics Data System (ADS)

    Vann, I. R.; Graham, R. H.; Hayward, A. B.

    Commonly the part of a mountain front which is visible at the surface consists of foreland-dipping thrust belt rocks elevated above their regional structural position and overlain more or less conformably by molasse. Several explanations for their geometry are possible. (1) Major detachments exist within or beneath the molasse resulting in transport of the foreland basin. Examples of this geometry come from the Swiss Molasse Plain, the Southern Pyrenees and the Mackenzie Mountains of Canada. (2) Displacement is lost on major backthrusts beneath the frontal monocline. Examples cited here are the Rockies of Alberta, the Sulaiman Ranges of Pakistan, the Mackenzies, and the Andes in Peru. (3) Thrust sheets travelled over an old land surface and syntectonic molasse contemporaneously offlaps the topographic high of the thrust front. This phenomenon occurs along the Alpine thrust front in Haute Provence. (4) The frontal fold represents deformation above a large-scale thrust tip. No unequivocal example of tip line strain at this scale has been recorded although this type of deformation may occur in the Brooks Range of Alaska. In many areas mountain fronts show a combination of these idealized geometries.

  19. The interplay between deformation and volcanic activity: new data from the central sector of the Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Isaia, Roberto; Sabatino, Ciarcia; Enrico, Iannuzzi; Ernesto, Prinzi; D'Assisi, Tramparulo Francesco; Stefano, Vitale

    2016-04-01

    The new excavation of a tunnel in the central sector of the Campi Flegrei caldera allowed us to collect new stratigraphic and structural data shedding light on the volcano-tectonic evolution of the last 10 ka. The analyzed sequences are composed by an alternation of volcanic, lacustrine, fluvial and marine sediments hosting several deformation structures such as faults, sedimentary dykes and fractures. A review of available well log togheter with the new data were used to perform a 3D reconstruction of paleo-surfaces resulted after the main volcanic and deformation episodes. Results show as the paleo-morphology was strictly controlled by faults and fractures that formed meso-scale channels and depressions subsequently filled by tephra and volcanoclastic sediments. The measured structures indicate an extensional deformation accompanying the ground uplift occurred in various stages of the caldera evolution. Stratigraphic relationships between structures and volcanic deposits further constrain the timing of the deformation phases. Presently an unrest phase of the Campi Flegrei caldera is marked by variations of different parameters such as ground deformation activities well recorded by GPS data, topographic leveling and satellite surveys. The results of this study provide further insight into the long term deformation pattern of the caldera and provide a key to interpret the ground deformation scenarios accompanying a possible resumption of volcanism.

  20. Active and long-lived permanent forearc deformation driven by the subduction seismic cycle

    NASA Astrophysics Data System (ADS)

    Aron Melo, Felipe Alejandro

    I have used geological, geophysical and engineering methods to explore mechanisms of upper plate, brittle deformation at active forearc regions. My dissertation particularly addresses the permanent deformation style experienced by the forearc following great subduction ruptures, such as the 2010 M w8.8 Maule, Chile and 2011 Mw9.0 Tohoku, Japan earthquakes. These events triggered large, shallow seismicity on upper plate normal faults above the rupture reaching Mw7.0. First I present new structural data from the Chilean Coastal Cordillera over the rupture zone of the Maule earthquake. The study area contains the Pichilemu normal fault, which produced the large crustal aftershocks of the megathrust event. Normal faults are the major neotectonic structural elements but reverse faults also exist. Crustal seismicity and GPS surface displacements show that the forearc experiences pulses of rapid coseismic extension, parallel to the heave of the megathrust, and slow interseismic, convergence-parallel shortening. These cycles, over geologic time, build the forearc structural grain, reactivating structures properly-oriented respect to the deformation field of each stage of the interplate cycle. Great subduction events may play a fundamental role in constructing the crustal architecture of extensional forearc regions. Static mechanical models of coseismic and interseismic upper plate deformation are used to explore for distinct features that could result from brittle fracturing over the two stages of the interplate cycle. I show that the semi-elliptical outline of the first-order normal faults along the Coastal Cordillera may define the location of a characteristic, long-lived megathrust segment. Finally, using data from the Global CMT catalog I analyzed the seismic behavior through time of forearc regions that have experienced great subduction ruptures >Mw7.7 worldwide. Between 61% and 83% of the cases where upper plate earthquakes exhibited periods of increased seismicity

  1. On the energy conservation during the active deformation in molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Zhong, Zheng

    2015-04-01

    In this paper, we examined the energy conservation for the current schemes of applying active deformation in molecular dynamics (MD) simulations. Specifically, two methods are examined. One is scaling the dimension of the simulation box and the atom positions via an affine transformation, suitable for the periodic system. The other is moving the rigid walls that interact with the atoms in the system, suitable for the non-periodic system. Based on the calculation of the external work and the internal energy change, we present that the atom velocities also need to be updated in the first deformation method; otherwise the energy conservation cannot be satisfied. The classic updating scheme is examined, in which any atom crossing the periodic boundary experiences a velocity delta that is equal to the velocity difference between the opposite boundaries. In addition, a new scheme which scales the velocities of all the atoms according to the strain increment is proposed, which is more efficient and realistic than the classic scheme. It is also demonstrated that the Virial stress instead of its interaction part is the correct stress definition that corresponds to Cauchy stress in the continuum mechanics.

  2. Kinematics of active deformation in the Sulaiman Lobe and Range, Pakistan

    NASA Astrophysics Data System (ADS)

    Bernard, M.; Shen-Tu, B.; Holt, W. E.; Davis, D. M.

    2000-06-01

    The western margin of the Indian plate is highly oblique to the direction of convergence between India and Asia and represents an excellent example of large-scale oblique continent-continent collision. Determining the strain field in western Pakistan and how it relates to the plate motion and plate margin geometry affords an exceptional opportunity for understanding oblique margin processes in general. Through the inversion of regional and teleseismic body waves, we have determined the source parameters of 10 moderate-sized earthquakes that occurred between 1964 and 1985 in and around the Sulaiman Range, Pakistan. The earthquakes are dominantly thrust events with slip vectors that are approximately perpendicular to the lobate Sulaiman mountain front. Slip vector orientations rotate 60°-70° from a N-S to a WNW-ESE direction of compression, consistent with the geometries of the complex, festoon-shaped mountain belts of this margin. We have estimated the spatial variation of the horizontal strain rate and velocity fields within Sulaiman using vertically averaged models that accommodate plate motion constraints within a deforming layer. The most important factors determining the style of strain rotation in the Sulaiman Lobe and Range are the presence of pure strike-slip motion along the Chaman Fault, and the relatively rigid and undeformed Katawaz Basin that is therefore allowed to translate obliquely relative to India. This same conclusion is obtained using either a three-dimensional, frictional, analogue model with significant basal tractions or a thin sheet viscous numerical model without basal tractions. Thrusting in a predominantly NW-SE direction in the Sulaiman Range accommodates 5-14 mm/yr of N-S motion between India-Eurasia and 3-6 mm/yr of E-W shortening. Seismic moment release this century within the India-Eurasia plate boundary zone, west of the western Himalayan Syntaxis, constitutes roughly 40% of the expected total seismic moment release for this time

  3. Quaternary grabens in southernmost Illinois: Deformation near an active intraplate seismic zone

    USGS Publications Warehouse

    Nelson, W.J.; Denny, F.B.; Follmer, L.R.; Masters, J.M.

    1999-01-01

    Narrow grabens displace Quaternary sediments near the northern edge of the Mississippi Embayment in extreme southern Illinois, east-central United States. Grabens are part of the Fluorspar Area Fault Complex (FAFC), which has been recurrently active throughout Phanerozoic time. The FAFC strikes directly toward the New Madrid Seismic Zone (NMSZ), scene of some of the largest intra-plate earthquakes in history. The NMSZ and FAFC share origin in a failed Cambrian rift (Reelfoot Rift). Every major fault zone of the FAFC in Illinois exhibits Quaternary displacement. The structures appear to be strike-slip pull-apart grabens, but the magnitude and direction of horizontal slip and their relationship to the current stress field are unknown. Upper Tertiary strata are vertically displaced more than 100 m, Illinoian and older Pleistocene strata 10 to 30 m, and Wisconsinan deposits 1 m or less. No Holocene deformation has been observed. Average vertical slip rates are estimated at 0.01 to 0.03 mm/year, and recurrence intervals for earthquakes of magnitude 6 to 7 are on the order of 10,000s of years for any given fault. Previous authors remarked that the small amount of surface deformation in the New Madrid area implies that the NMSZ is a young feature. Our findings show that tectonic activity has shifted around throughout the Quaternary in the central Mississippi Valley. In addition to the NMSZ and southern Illinois, the Wabash Valley (Illinois-Indiana), Benton Hills (Missouri), Crowley's Ridge (Arkansas-Missouri), and possibly other sites have experienced Quaternary tectonism. The NMSZ may be only the latest manifestation of seismicity in an intensely fractured intra-plate region.

  4. Managing Contradictions from the Middle: A Cultural Historical Activity Theory Investigation of Front-Line Supervisors' Learning Lives

    ERIC Educational Resources Information Center

    Lord, Ramo J.

    2009-01-01

    This study focused on front-line supervisors in a union shop, steel-production plant and how they learn to successfully negotiate their role with in the corporation's division of labor. Negotiating their role means continued practice in how issues of standpoint, agency, power, oppression, habits, knowledge, related business concerns, mediating…

  5. Influence of thermally activated processes on the deformation behavior during low temperature ECAP

    NASA Astrophysics Data System (ADS)

    Fritsch, S.; Scholze, M.; F-X Wagner, M.

    2016-03-01

    High strength aluminum alloys are generally hard to deform. Therefore, the application of conventional severe plastic deformation methods to generate ultrafine-grained microstructures and to further increase strength is considerably limited. In this study, we consider low temperature deformation in a custom-built, cooled equal channel angular pressing (ECAP) tool (internal angle 90°) as an alternative approach to severely plastically deform a 7075 aluminum alloy. To document the maximum improvement of mechanical properties, these alloys are initially deformed from a solid solution heat-treated condition. We characterize the mechanical behavior and the microstructure of the coarse grained initial material at different low temperatures, and we analyze how a tendency for the PLC effect and the strain-hardening rate affect the formability during subsequent severe plastic deformation at low temperatures. We then discuss how the deformation temperature and velocity influence the occurrence of PLC effects and the homogeneity of the deformed ECAP billets. Besides the mechanical properties and these microstructural changes, we discuss technologically relevant processing parameters (such as pressing forces) and practical limitations, as well as changes in fracture behavior of the low temperature deformed materials as a function of deformation temperature.

  6. Injury Risk for Children in Rear Impacts: Role of the Front Seat Occupant

    PubMed Central

    Jermakian, Jessica Steps; Arbogast, Kristy B.; Durbin, Dennis R.; Kallan, Michael J.

    2008-01-01

    As more children move to the rear rows, there is a need to understand the rear impact environment for children to guide future regulatory and due care activities in this impact direction. A probability sample of 1,035 restrained child occupants, aged 0–12 years, seated in a second row outboard position in rear impact tow-away crashes, weighted to represent 10,079 children, was collected from an on-going child specific crash surveillance system between 3/1/00 and 12/31/06. These data were analyzed to quantify the overall injury risk and the influence of both front seat occupant presence and reported front seat back deformation on injury risk. Overall risk of AIS 2+ injury for restrained child occupants seated in the rear row outboard position in rear impact crashes was 2.3%. Occupants were seated in front of these children in 71% of cases and deformation of the front seat back into the child’s space was reported in 8% of cases. For those children with seatback deformation occurring directly in front of them, there was a doubling of the injury risk (4.8% vs. 2.1%, adjusted OR=2.4, 95% CI=1.2–4.8). This paper provides the first population-based estimates of the injury risk of rear row-seated children in rear impact crash events and points to the importance of understanding the role of front seat back design on rear impact injury risk for both the front seat and rear seat occupants. PMID:19026228

  7. Injury risk for children in rear impacts: role of the front seat occupant.

    PubMed

    Jermakian, Jessica Steps; Arbogast, Kristy B; Durbin, Dennis R; Kallan, Michael J

    2008-10-01

    As more children move to the rear rows, there is a need to understand the rear impact environment for children to guide future regulatory and due care activities in this impact direction. A probability sample of 1,035 restrained child occupants, aged 0-12 years, seated in a second row outboard position in rear impact tow-away crashes, weighted to represent 10,079 children, was collected from an on-going child specific crash surveillance system between 3/1/00 and 12/31/06. These data were analyzed to quantify the overall injury risk and the influence of both front seat occupant presence and reported front seat back deformation on injury risk. Overall risk of AIS 2+ injury for restrained child occupants seated in the rear row outboard position in rear impact crashes was 2.3%. Occupants were seated in front of these children in 71% of cases and deformation of the front seat back into the child's space was reported in 8% of cases. For those children with seatback deformation occurring directly in front of them, there was a doubling of the injury risk (4.8% vs. 2.1%, adjusted OR=2.4, 95% CI=1.2-4.8). This paper provides the first population-based estimates of the injury risk of rear row-seated children in rear impact crash events and points to the importance of understanding the role of front seat back design on rear impact injury risk for both the front seat and rear seat occupants. PMID:19026228

  8. Active deformation processes of the Northern Caucasus deduced from the GPS observations

    NASA Astrophysics Data System (ADS)

    Milyukov, Vadim; Mironov, Alexey; Rogozhin, Eugeny; Steblov, Grigory; Gabsatarov, Yury

    2015-04-01

    The Northern Caucasus, as a part of the Alpine-Himalayan mobile belt, is a zone of complex tectonics associated with the interaction of the two major tectonic plates, Arabian and Eurasian. The first GPS study of the contemporary geodynamics of the Caucasus mountain system were launched in the early 1990s in the framework of the Russia-US joint project. Since 2005 observations of the modern tectonic motion of the Northern Caucasus are carried out using the continuous GPS network. This network encompasses the territory of three Northern Caucasian Republics of the Russian Federation: Karachay-Cherkessia, Kabardino-Balkaria, and North Ossetia. In the Ossetian part of the Northern Caucasus the network of GPS survey-mode sites has been deployed as well. The GPS velocities confirm weak general compression of the Northern Caucasus with at the rate of about 1-2 mm/year. This horizontal motion at the boundary of the Northern Caucasus with respect to the Eurasian plate causes the higher seismic and tectonic activity of this transition zone. This result confirms that the source of deformation of the Northern Caucasus is the sub-meridional drift of the Arabian plate towards the adjacent boundary of the Eastern European part of the Eurasian lithospheric plate. The concept of such convergence implies that the Caucasian segment of the Alpine-Himalayan mobile belt is under compression, the layers of sedimentary and volcanic rocks are folded, the basement blocks are subject to shifts in various directions, and the upper crust layers are ruptured by reverse faults and thrusts. Weak deviation of observed velocities from the pattern corresponding to homogeneous compression can also be revealed, and numerical modeling of deformations of major regional tectonic structures, such as the Main Caucasus Ridge, can explain this. The deformation tensor deduced from the velocity field also exhibits the sub-meridional direction of the major compressional axes which coincides with the direction of

  9. Structural deformation measurement via efficient tensor polynomial calibrated electro-active glass targets

    NASA Astrophysics Data System (ADS)

    Gugg, Christoph; Harker, Matthew; O'Leary, Paul

    2013-03-01

    This paper describes the physical setup and mathematical modelling of a device for the measurement of structural deformations over large scales, e.g., a mining shaft. Image processing techniques are used to determine the deformation by measuring the position of a target relative to a reference laser beam. A particular novelty is the incorporation of electro-active glass; the polymer dispersion liquid crystal shutters enable the simultaneous calibration of any number of consecutive measurement units without manual intervention, i.e., the process is fully automatic. It is necessary to compensate for optical distortion if high accuracy is to be achieved in a compact hardware design where lenses with short focal lengths are used. Wide-angle lenses exhibit significant distortion, which are typically characterized using Zernike polynomials. Radial distortion models assume that the lens is rotationally symmetric; such models are insufficient in the application at hand. This paper presents a new coordinate mapping procedure based on a tensor product of discrete orthogonal polynomials. Both lens distortion and the projection are compensated by a single linear transformation. Once calibrated, to acquire the measurement data, it is necessary to localize a single laser spot in the image. For this purpose, complete interpolation and rectification of the image is not required; hence, we have developed a new hierarchical approach based on a quad-tree subdivision. Cross-validation tests verify the validity, demonstrating that the proposed method accurately models both the optical distortion as well as the projection. The achievable accuracy is e <= +/-0.01 [mm] in a field of view of 150 [mm] x 150 [mm] at a distance of the laser source of 120 [m]. Finally, a Kolmogorov Smirnov test shows that the error distribution in localizing a laser spot is Gaussian. Consequently, due to the linearity of the proposed method, this also applies for the algorithm's output. Therefore, first

  10. Active anthropogenic and surface salt deformation measured by InSAR, northwestern China

    NASA Astrophysics Data System (ADS)

    Colon, C.; Webb, A. G.; Lasserre, C.; Doin, M. P.

    2014-12-01

    Despite the global occurrence of salt, very few salt bodies outcrop and are presently preserved at the surface. Because of this much of our knowledge on salt structures is sourced from subsurface imaging and modeling and less from field based studies. Using interferometry of synthetic aperture radar (InSAR) we monitor surface displacements across four surface salt outcrops in the western margin of the Kuqa fold-thrust belt of Xinjiang Province, China. An InSAR time series was constructed from 40 Envisat ASAR C-band images between June 2003 and October 2010. Interferometric processing was completed using the New Small Baseline Algorithm Subset (NSBAS). These poorly studied salt structures provide a fresh opportunity to study how salt behaves on the surface. The salt bodies outcrop along an active intracontinental thrust system between the Tian Shan and Tarim basin to the south. The four surface namakiers (salt glaciers) were analyzed in this study include: the Quele, Awate, Bozidun, and an unnamed structure referred to as the Western namakier. The ~35 km long Quele namakier is a line-sourced structure advancing along the Quele salt thrust. The other three namakiers range between ~1-3 km long and are point-sourced structures. The namakiers studied display non-steady deformation with rates of displacement varying between uplifts of up to +4 cm/yr and subsidence rates of -4 cm/yr. Additionally, the Kuqa fold-thrust belt hosts a number of hydrocarbon fields and InSAR measurements detect significant anthropogenic deformation associated with hydrocarbon extraction and fluid injection.

  11. Quaternary deformation

    SciTech Connect

    Brown, R.D. Jr.

    1990-01-01

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

  12. Deformation twinning activated α --> ω transformation in titanium under shock compression

    NASA Astrophysics Data System (ADS)

    Zong, Hongxiang; Lookman, Turab

    Materials dynamics, especially the behavior of solids under extreme compression, is a topic of broad scientific and technological interest. However, less is known of the role of grain boundary structures on the shock response of hexagonal-close-packed metals. We use molecular dynamics simulations to study deformation mechanisms in shock compressed Ti bicrystals containing three types of grain boundary (GB) microstructures, i.e., coherent twin boundaries (CTBs), symmetric incoherent twin boundaries (ITB) and {1-210}asymmetric tilt grain boundaries. Our results show that both dislocation activity and the α -> ω phase transformation in Ti are sensitive to the GB characteristics. In particular, we find that the elastic shock wave can readily trigger the α -> ω transformation at CTBs but not at the other two GBs, and the activation of the α -> ω transformation at CTBs leads to considerable wave attenuation (i.e., the elastic precursor decay). Combined with first principle calculations, we find that CTBs can facilitate the overcoming of the energy barrier for the α -> ω transformation. Our findings have potential implications for interface engineering and materials design under extreme conditions.

  13. Microearthquake activity, lithospheric structure, and deformation modes at an amagmatic ultraslow spreading Southwest Indian Ridge segment

    NASA Astrophysics Data System (ADS)

    Schmid, Florian; Schlindwein, Vera

    2016-07-01

    While nascent oceanic lithosphere at slow to fast spreading mid-ocean ridges (MOR) is relatively well studied, much less is known about the lithospheric structure and properties at ultraslow MORs. Here we present microearthquake data from a 1 year ocean bottom seismometer deployment at the amagmatic, oblique supersegment of the ultraslow spreading Southwest Indian Ridge. A refraction seismic experiment was performed to constrain upper lithosphere P-velocities and results were used to construct a 1D velocity model for earthquake location. Earthquake foci were located individually and subsequently relocated relative to each other to sharpen the image of seismically active structures. Frequent earthquake activity extends to 31 km beneath the seafloor, indicating an exceptionally thick brittle lithosphere and an undulating brittle-ductile transition that implies significant variations in the along-axis thermal structure of the lithosphere. We observe a strong relation between petrology, microseismicity distribution, and topography along the ridge axis: Peridotite-dominated areas associate with deepest hypocenters, vast volumes of lithosphere that deforms aseismically as a consequence of alteration, and the deepest axial rift valley. Areas of basalt exposure correspond to shallower hypocenters, shallower and more rugged axial seafloor. Focal mechanisms deviate from pure extension and are spatially variable. Earthquakes form an undulating band of background seismicity and do not delineate discrete detachment faults as common on slow spreading ridges. Instead, the seismicity band sharply terminates to the south, immediately beneath the rift boundary. Considering the deep alteration, large steep boundary faults might be present but are entirely aseismic.

  14. Active deformation of the Congo intracratonic basin and its eastern margin

    NASA Astrophysics Data System (ADS)

    Everaerts, Michel; Delvaux, Damien; Beoka, Ateba

    2015-04-01

    The Congo basin, one of the largest intracontinental sedimentary basin in the world, developed in Central Africa since the early Neoproterozoic during successive tectonically controlled stages. It formed over an heterogeneous basement as highlighted by aeromagnetic data, composed of Archean cores welded by Proterozoic mobile belts. It contains an average of 4 km and locally up to 8 km of Neoproterozoic to Mesozoic sediments. Since late Mesozoic (Cenomanian), it was submitted to intraplate stresses due to the action of ridge-push forces related to the spreading of the South Atlantic. As a result, most part of the basin entered in an erosional stage while only a small part is still accumulating sediments. Active deformation of this vast region (5°N-11°S and 12-27°E) is indicated by a certain level of seismic activity, with about 270 earthquakes instrumentally recorded with magnitudes ranging from 2.2 to 5.5 inside the basin and up to up to 6.3 along its NW (Gabon) and NW (Katanga) margins. The dozen available focal mechanisms indicate that the basin is under ENE-WSW horizontal compression, under a compressional regime in its center and strike-slip regime along its northern and western margins. Low-angle slickensided fault planes are observed in the Samba cored well, constraining the onset of the recent compressional setting in the late Albian, at a time when South America was already separated from Africa and the South Atlantic Ridge was already functioning. Although subtle, recent tectonic deformations (faulting and buckling undulations) can also be inferred from the reflection seismic profiles and the topography and river network. The overall neotectonic picture is inferred as reflecting the development of compressional tectonic instabilities in the basin fill and its margins under the action of intraplate stress field and the control of the basement heterogeneity. This is a contribution to preparation of the Seismotectonic Map of Africa by the working group of

  15. Faults Activities And Crustal Deformation near Hualien City, eastern Taiwan Analysed By Persistent Scatterer InSAR

    NASA Astrophysics Data System (ADS)

    Lu, C.; Lin, M.; Yen, J.; Chang, C.

    2008-12-01

    Hualien is located in eastern part of Taiwan, and is the collision boundary in the northern of Huatung Longitudinal Valley between the Philippine Sea tectonic plate and Eurasian tectonic plate(Biq, 1981; Barrier and Angelier, 1986). There are several active faults, such as Milun fault, Beipu fault and Minyi fault, pass through the Hualien city, and create many crustal deformation. According to previous researches (Hsu, 1956; Lin, 1962; Yu, 1997) we know Milun fault is a thrust and left lateral fault, and the fault plane incline to east. Minyi fault also is a left lateral and a slight reverse fault, but it's fault plane incline to west. (Chang, 1994; Yu, 1997) We applied the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR, Hooper, 2007) to observe temporally-variable processes of Hualien city between 2004 to 2008. At the same time, precise leveling and GPS data were taken for the auxiliary data to verify the deformation rate and pattern in this area. In the Hualien city area, our observation showed that the active faults separate this area into several distinct blocks. Most of the blocks moved slowly, but the hanging wall of the Milun fault decreases 5- 8mm in line of sight (LOS) direction between 15 May 2004 to 24 Feb 2007, then increases 3-6mm in LOS between 1 Dec 2007 to 5 Jan 2008. The deformation reversed its direction in 2007. The western surface of Hualien City displays continuous deformation about 1.5-2mm/yr , which spread along the Beipu fault. Our preliminary investigation indicated that between late 2004 and middle 2005 there had been an abrupt increase in seismicity, which coincided with PSInSAR observation of a large displacement. The distribution of shallow source earthquakes correlate with the area with large deformation. Our following works include continuing observation of the Hualien City, and decipher the relationship between earthquakes and surface deformation, and model the fault action in Hualien City with time series.

  16. Front-line ownership: imagine.

    PubMed

    Matlow, Anne

    2013-01-01

    When used in a military context, the term front line refers to the interface between enemies in action on the battlefield. In a non-military context, the front line is the site where the core activity defining a particular industry takes place, and those working there are key to successful operations. In healthcare, the need to improve patient safety has become a global imperative, and an armamentarium of strategies, tools and technological approaches have been adapted or developed for this context. Often neglected, however, have been strategies to engage the healthcare workers, those at the front line, in the cause.In order for healthcare to function error free, we must assume the characteristics of high-reliability organizations. In particular, the ability to bounce back, to be resilient in the face of a catastrophe, is of paramount importance. Those working at the front line may have the answers. We need to create an opportunity for them to be heard.`

  17. Front matter.

    PubMed

    2015-01-01

    has defined four basic areas to be managed in the new care model: address the big data challenges; foster meaningful innovation; understand and address the potential new risks; and support concerted effort to un-silo communities for a virtual care future. The multilateral benefits of pHealth technologies for all stakeholder communities including patients, citizens, health professionals, politicians, healthcare establishments, and companies from the biomedical technology, pharmaceutical, and telecommunications domain gives enormous potential, not only for medical quality improvement and industrial competitiveness, but also for managing health care cost. The pHealth 2015 Conference thankfully benefits from the experience and the lessons learned from the organizing committees of previous pHealth events, particularly 2009 in Oslo, 2010 in Berlin, 2011 in Lyon, 2012 in Porto, 2013 in Tallinn, and 2014 Vienna. The 2009 conference brought up the interesting idea of having special sessions, focusing on a particular topic, and being organized by a mentor/moderator. The Berlin event in 2010 initiated workshops on particular topics prior to the official kick-off of the conference. Lyon in 2011 initiated the launch of socalled dynamic demonstrations allowing the participants to dynamically show software and hardware solutions on the fly without needing a booth. Implementing preconference events, the pHealth 2012 in Porto gave attendees a platform for presenting and discussing recent developments and provocative ideas that helped to animate the sessions. Highlight of pHealth 2013 in Tallinn was the special session on European projects' success stories, but also presentations on the newest paradigm changes and challenges coming up with Big Data, Analytics, Translational and Nano Medicine, etc. Vienna in 2014 focused on lessons learned from international and national R&D activities and practical solutions, and especially from the new EU Framework Program for Research and Innovation

  18. Front matter.

    PubMed

    2015-01-01

    has defined four basic areas to be managed in the new care model: address the big data challenges; foster meaningful innovation; understand and address the potential new risks; and support concerted effort to un-silo communities for a virtual care future. The multilateral benefits of pHealth technologies for all stakeholder communities including patients, citizens, health professionals, politicians, healthcare establishments, and companies from the biomedical technology, pharmaceutical, and telecommunications domain gives enormous potential, not only for medical quality improvement and industrial competitiveness, but also for managing health care cost. The pHealth 2015 Conference thankfully benefits from the experience and the lessons learned from the organizing committees of previous pHealth events, particularly 2009 in Oslo, 2010 in Berlin, 2011 in Lyon, 2012 in Porto, 2013 in Tallinn, and 2014 Vienna. The 2009 conference brought up the interesting idea of having special sessions, focusing on a particular topic, and being organized by a mentor/moderator. The Berlin event in 2010 initiated workshops on particular topics prior to the official kick-off of the conference. Lyon in 2011 initiated the launch of socalled dynamic demonstrations allowing the participants to dynamically show software and hardware solutions on the fly without needing a booth. Implementing preconference events, the pHealth 2012 in Porto gave attendees a platform for presenting and discussing recent developments and provocative ideas that helped to animate the sessions. Highlight of pHealth 2013 in Tallinn was the special session on European projects' success stories, but also presentations on the newest paradigm changes and challenges coming up with Big Data, Analytics, Translational and Nano Medicine, etc. Vienna in 2014 focused on lessons learned from international and national R&D activities and practical solutions, and especially from the new EU Framework Program for Research and Innovation

  19. Active oil-water interfaces: buckling and deformation of oil drops by bacteria

    NASA Astrophysics Data System (ADS)

    Juarez, Gabriel; Stocker, Roman

    2014-11-01

    Bacteria are unicellular organisms that seek nutrients and energy for growth, division, and self-propulsion. Bacteria are also natural colloidal particles that attach and self-assemble at liquid-liquid interfaces. Here, we present experimental results on active oil-water interfaces that spontaneously form when bacteria accumulate or grow on the interface. Using phase-contrast and fluorescence microscopy, we simultaneously observed the dynamics of adsorbed Alcanivorax bacteria and the oil-water interface within microfluidic devices. We find that, by growing and dividing, adsorbed bacteria form a jammed monolayer of cells that encapsulates the entire oil drop. As bacteria continue to grow at the interface, the drop buckles and the interface undergoes strong deformations. The bacteria act to stabilize non-equilibrium shapes of the oil-phase such wrinkling and tubulation. In addition to presenting a natural example of a living interface, these findings shape our understanding of microbial degradation of oil and may have important repercussions on engineering interventions for oil bioremediation.

  20. Tectonic history and thrust-fold deformation style of seismically active structures near Coalinga

    SciTech Connect

    Namson, J.S. ); Davis, T.L.; Lagoe, M.B.

    1990-01-01

    The stratigraphy of the Coalinga region can be divided into tectostratigraphic facies whose boundaries delineate two major tectonic events - one in the mid-Cenozoic (38-17 Ma) and one in the late Cenozoic (less than 3 Ma). The succession of these tectostratigraphic facies, and an integration of geology, subsurface well data, a seismic-reflection profile, and earthquake seismicity on a retrodeformable cross section, yield a model for the tectonic evolution of the Coalinga region. This model suggests that the structural style of both deformational events is characteristic of fold and thrust belts. The model also indicates that the causative fault of the May 2 earthquake is a ramped thrust. The results of this study, in combination with regional geologic relations, suggest that the Coalinga region is part of an active fold and thrust belt which borders the west and south sides of the San Joaquin Valley. The potential for future earthquakes due to movement of other blind thrust faults within this belt should be evaluated.

  1. Front Matter.

    PubMed

    2016-01-01

    On behalf of the Scientific Program Committee, I extend a warm welcome to the IMIA-NI members, students, practitioners, informatics researchers, industry partners, and others interested in health and nursing informatics who have come to attend the NI 2016, 13th International Congress on Nursing Informatics. NI 2016 is a biennial conference of the IMIA-NI and the leading scientific meeting for health and nursing informatics research and practice. NI 2016 presents work not only from the discipline of nursing but also from many other disciplines and specialties including both basic and applied informatics. The theme of NI 2016 is eHealth for all: Every level collaboration - From project to realization. The theme reflects the major challenges we face in healthcare today, that is, the need to collaborate at every level to achieve our goal of Health For All. NI 2016 offers a variety of topics on the conference theme. The mission of the Scientific Program Committee is to solicit for, evaluate and schedule NI 2016 conference program to be consistent with the goal of the IMIA-NI. We received 445 submissions for papers, posters, short communications, panels, workshops, demonstrations, student competitions and tutorials from more than 40 countries. Each submission was reviewed by three reviewers selected from a panel of more than 963 experts. Reviewers' feedback was provided to the authors and every effort was made to ensure the best submissions given the constraints of the conference timetable. In the end, a total of 332 submissions were selected. The result of the Scientific Program Committee's activity is reflected in the Conference Program and Proceedings. The proceedings contain OA full papers, indexed in MEDLINE, and also workshops, panels and posters summaries. The Scientific Program Committee has prepared a wonderful program. We have six keynote speakers addressing the state-of-the-art for health and nursing informatics ranging from data, to healthcare delivery to the

  2. Front Matter.

    PubMed

    2016-01-01

    On behalf of the Scientific Program Committee, I extend a warm welcome to the IMIA-NI members, students, practitioners, informatics researchers, industry partners, and others interested in health and nursing informatics who have come to attend the NI 2016, 13th International Congress on Nursing Informatics. NI 2016 is a biennial conference of the IMIA-NI and the leading scientific meeting for health and nursing informatics research and practice. NI 2016 presents work not only from the discipline of nursing but also from many other disciplines and specialties including both basic and applied informatics. The theme of NI 2016 is eHealth for all: Every level collaboration - From project to realization. The theme reflects the major challenges we face in healthcare today, that is, the need to collaborate at every level to achieve our goal of Health For All. NI 2016 offers a variety of topics on the conference theme. The mission of the Scientific Program Committee is to solicit for, evaluate and schedule NI 2016 conference program to be consistent with the goal of the IMIA-NI. We received 445 submissions for papers, posters, short communications, panels, workshops, demonstrations, student competitions and tutorials from more than 40 countries. Each submission was reviewed by three reviewers selected from a panel of more than 963 experts. Reviewers' feedback was provided to the authors and every effort was made to ensure the best submissions given the constraints of the conference timetable. In the end, a total of 332 submissions were selected. The result of the Scientific Program Committee's activity is reflected in the Conference Program and Proceedings. The proceedings contain OA full papers, indexed in MEDLINE, and also workshops, panels and posters summaries. The Scientific Program Committee has prepared a wonderful program. We have six keynote speakers addressing the state-of-the-art for health and nursing informatics ranging from data, to healthcare delivery to the

  3. Front Matter.

    PubMed

    2016-01-01

    Can bad health informatics kill? A similar question has been asked a decade ago by one of the editors of this book on evidence-based health informatics [1]. And indeed, when informatics methodology and information and communication technology (ICT) are used inappropriately this can cause severe negative effects. On the other hand we will probably all agree with her, when she writes in the same article that it "is evident that the use of modern ICT offers tremendous opportunities to support health care professionals and to increase efficiency, effectiveness and appropriateness of care" [1]. Even earlier, more than 15 years ago, the other editor stated that it "is unfortunately a truism in health care informatics… that evaluation is undertaken rarely and inadequately" and he concludes, among others, that "integrated information systems also give new opportunity to provide effective health care service evaluation, and thus a much more robust future evidence base" [2]. As perspective he writes that "a deeper and longer-term evaluation philosophy is needed which does not stop after the initial confirmation of system functioning, but continues on with a deepening into the effects on the individual clinical services, and then on the host user organisation" [2]. Both colleagues worked during recent years continuously and intensively on how to better evaluate health care processes and outcomes in the context of health information systems, so that informatics tools and information management strategies are not 'just' applied in this context, but that their evidence has also been evaluated according to current good scientific practice. It is probably no surprise to find later joint papers of them on evidence-based health informatics, reporting about their international activities there [3]. Today there is indeed still a discrepancy in making decisions on health information system architectures, infrastructures and tools, related to considerable investments for health care

  4. Structural deformation and sedimentation in an active Caldera, Rabaul, Papua New Guinea

    USGS Publications Warehouse

    Greene, H. Gary; Tiffin, D.L.; McKee, C.O.

    1986-01-01

    Recent seismic and tectonic activity in Rabaul Caldera, Papua New Guinea, suggests that magma is accumulating at a shallow depth beneath this partially submerged structure and that a new volcano may be developing. Changes in onshore elevation since 1971 (as much as 2 m on south Matupit Island) indicate that rapid and large-scale uplifts have occurred on the seafloor near the center of the caldera. The frequency of seismic events within the caldera has also increased during this period. Earthquake locations define an elliptical ring surrounding the center of this uplift within the caldera. A marine geophysical survey in 1982 by the U.S. Geological Survey's R/V "S.P. Lee" in Rabaul Caldera shows the development of a bulge in the seafloor near the center of the caldera. High-resolution seismic reflection profiles show that this bulge consists of two domal uplifts bounded and separated by two major north-south-trending fault zones. Deformed sediments overlie these zones; a prominent slump flanks the area of the bulge. Five major acoustic units were identified in the seismic reflection profiles: an acoustic basement and four sedimentary units consisting of irregularly layered, cross-layered, contorted, and well-layered sequences. The acoustic basement is probably composed of crystalline volcanic rocks, and the layered acoustic units are probably sediments, primarily ash deposited in different environments. The cross-layered, irregularly layered, and contorted units appear to have been deposited in a dynamic environment subjected to strong currents, seismicity, and/or mass wasting, while the well-layered units were deposited in a low-energy environment. Locally, well-layered sequences interfinger with the other sedimentary units, indicating a transitional environment that alternated between high-energy and low-energy depositional processes. A submarine channel cuts most of the acoustic units and appears to be the conduit for sediment transport out of the caldera; it

  5. A High-Performance Deformable Mirror with Integrated Driver ASIC for Space Based Active Optics

    NASA Astrophysics Data System (ADS)

    Shelton, Chris

    Direct imaging of exoplanets is key to fully understanding these systems through spectroscopy and astrometry. The primary impediment to direct imaging of exoplanets is the extremely high brightness ratio between the planet and its parent star. Direct imaging requires a technique for contrast suppression, which include coronagraphs, and nulling interferometers. Deformable mirrors (DMs) are essential to both of these techniques. With space missions in mind, Microscale is developing a novel DM with direct integration of DM and its electronic control functions in a single small envelope. The Application Specific Integrated Circuit (ASIC) is key to the shrinking of the electronic control functions to a size compatible with direct integration with the DM. Through a NASA SBIR project, Microscale, with JPL oversight, has successfully demonstrated a unique deformable mirror (DM) driver ASIC prototype based on an ultra-low power switch architecture. Microscale calls this the Switch-Mode ASIC, or SM-ASIC, and has characterized it for a key set of performance parameters, and has tested its operation with a variety of actuator loads, such as piezo stack and unimorph, and over a wide temperature range. These tests show the SM-ASIC's capability of supporting active optics in correcting aberrations of a telescope in space. Microscale has also developed DMs to go with the SM-ASIC driver. The latest DM version produced uses small piezo stack elements in an 8x8 array, bonded to a novel silicon facesheet structure fabricated monolithically into a polished mirror on one side and mechanical linkage posts that connect to the piezoelectric stack actuators on the other. In this Supporting Technology proposal we propose to further develop the ASIC-DM and have assembled a very capable team to do so. It will be led by JPL, which has considerable expertise with DMs used in Adaptive Optics systems, with high-contrast imaging systems for exoplanet missions, and with designing DM driver

  6. Automatic corpus callosum segmentation using a deformable active Fourier contour model

    NASA Astrophysics Data System (ADS)

    Vachet, Clement; Yvernault, Benjamin; Bhatt, Kshamta; Smith, Rachel G.; Gerig, Guido; Cody Hazlett, Heather; Styner, Martin

    2012-03-01

    The corpus callosum (CC) is a structure of interest in many neuroimaging studies of neuro-developmental pathology such as autism. It plays an integral role in relaying sensory, motor and cognitive information from homologous regions in both hemispheres. We have developed a framework that allows automatic segmentation of the corpus callosum and its lobar subdivisions. Our approach employs constrained elastic deformation of flexible Fourier contour model, and is an extension of Szekely's 2D Fourier descriptor based Active Shape Model. The shape and appearance model, derived from a large mixed population of 150+ subjects, is described with complex Fourier descriptors in a principal component shape space. Using MNI space aligned T1w MRI data, the CC segmentation is initialized on the mid-sagittal plane using the tissue segmentation. A multi-step optimization strategy, with two constrained steps and a final unconstrained step, is then applied. If needed, interactive segmentation can be performed via contour repulsion points. Lobar connectivity based parcellation of the corpus callosum can finally be computed via the use of a probabilistic CC subdivision model. Our analysis framework has been integrated in an open-source, end-to-end application called CCSeg both with a command line and Qt-based graphical user interface (available on NITRC). A study has been performed to quantify the reliability of the semi-automatic segmentation on a small pediatric dataset. Using 5 subjects randomly segmented 3 times by two experts, the intra-class correlation coefficient showed a superb reliability (0.99). CCSeg is currently applied to a large longitudinal pediatric study of brain development in autism.

  7. Measuring active deformation of the Yakima fold and thrust belt using GPS and InSAR

    NASA Astrophysics Data System (ADS)

    Schmalzle, G. M.; Baker, M. S.; McCaffrey, R.; King, R. W.; Osmanoglu, B.

    2011-12-01

    The Yakima fold-thrust belt (YFTB; also known as Yakima Fold Belt), forming the distinct geomorphology of northernmost Oregon and south-central Washington, is one of the few actively deforming fold and thrust belts in the conterminous United States. Although controversial, currently available data suggest that the YFTB is "thick-skinned", i.e., its faults penetrate the seismogenic layer, allowing for large (~M7) earthquakes. The YFTB is bisected by the Olympic-Wallowa Lineament (OWL) that runs from eastern Washington into the highly populated Puget Sound. Together, the YFTB and OWL make up the boundary between the clockwise rotating Oregon block and eastern Washington, which is largely moving with the North American plate. Paleomagnetic data suggest that Oregon has been rotating at its present (GPS-derived) rate for more than 15 million years with the predicted consequence of a long history of shortening across the YFTB. GPS data obtained over the past ~20 years indicate a NE-directed shortening strain rate of about 9 x 10^-9 /yr, but how this strain is partitioned across the YFTB is unclear due to the sparse locations of GPS sites. We use Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data to examine the degree to which strain rates are localized or distributed within this continental thrust belt, shedding light on the controversy regarding the behavior of the continental lithosphere under contraction. These data are compared to local seismicity, gravity surveys, recent high-resolution aeromagnetic work and paleoseismic studies.

  8. MAGNETIC LIQUID DEFORMABLE MIRRORS FOR ASTRONOMICAL APPLICATIONS: ACTIVE CORRECTION OF OPTICAL ABERRATIONS FROM LOWER-GRADE OPTICS AND SUPPORT SYSTEM

    SciTech Connect

    Borra, E. F.

    2012-08-01

    Deformable mirrors are increasingly used in astronomy. However, they still are limited in stroke for active correction of high-amplitude optical aberrations. Magnetic liquid deformable mirrors (MLDMs) are a new technology that has the advantages of high-amplitude deformations and low costs. In this paper, we demonstrate extremely high strokes and interactuator strokes achievable by MLDMs which can be used in astronomical instrumentation. In particular, we consider the use of such a mirror to suggest an interesting application for the next generation of large telescopes. We present a prototype 91 actuator deformable mirror made of a magnetic liquid (ferrofluid). This mirror uses a technique that linearizes the response of such mirrors by superimposing a large and uniform magnetic field on the magnetic field produced by an array of small coils. We discuss experimental results that illustrate the performance of MLDMs. A most interesting application of MLDMs comes from the fact they could be used to correct the aberrations of large and lower optical quality primary mirrors held by simple support systems. We estimate basic parameters of the needed MLDMs, obtaining reasonable values.

  9. Railway deformation detected by DInSAR over active sinkholes in the Ebro Valley evaporite karst, Spain

    NASA Astrophysics Data System (ADS)

    Galve, J. P.; Castañeda, C.; Gutiérrez, F.

    2015-11-01

    Subsidence was measured for the first time on railway tracks in the central sector of Ebro Valley (NE Spain) using Differential Synthetic Aperture Radar Interferometry (DInSAR) techniques. This area is affected by evaporite karst and the analysed railway corridors traverse active sinkholes that produce deformations in these infrastructures. One of the railway tracks affected by slight settlements is the Madrid-Barcelona high-speed line, a form of transport infrastructure highly vulnerable to ground deformation processes. Our analysis based on DInSAR measurements and geomorphological surveys indicates that this line shows dissolution-induced subsidence and compaction of anthropogenic deposits (infills and embankments). Significant sinkhole-related subsidence was also measured by DInSAR techniques on the Castejón-Zaragoza conventional railway line. This study demonstrates that DInSAR velocity maps, coupled with detailed geomorphological surveys, may help in the identification of the railway track sections that are affected by active subsidence.

  10. Perceptual transparency from image deformation.

    PubMed

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

    2015-08-18

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

  11. Experimental Deformation of Olivine Single Crystal at Mantle P and T: Pressure Effect on Olivine Dislocation Slip-System Activities

    NASA Astrophysics Data System (ADS)

    Paul, R.; Girard, J.; Chen, J.; Amiguet, E.

    2008-12-01

    Seismic velocity anisotropies observed in the upper mantle are interpreted from lattice preferred orientations (LPO) produced experimentally in olivine, which depends on the dominant dislocation slip systems. At low pressure P<3 GPa, mantle temperature (T) and in dry conditions, olivine [100] dislocation slip dominates the less active [001] slip. This tends to align crystal fast velocity [100] axis with the principal shear direction. Yet recent high-pressure deformation experiments (Couvy et al., 2004, EJM, 16, 877; Raterron et al., 2007, Am. Min., 92, 1436; Raterron et al., 2008, Phys. Earth Planet. Int., doi:10.1016/j.pepi.2008.07.026) show that [001](010) slip system dominates [100](010) system in the (P,T) range of the deep upper mantle. This may promote a shear-parallel slow-velocity [001] axis and may explain the seismic-velocity attenuation observed at depth >200 km (Mainprice et al., 2005, Nature, 433, 731). In order to further constrain the effect of P on olivine slip system activities, which is classically quantified by the activation volume V* in power creep laws, deformation experiments were carried out in poor water condition, at P>5 GPa and T=1400°C, on pure forsterite (Fo100) and San Carlos olivine crystals, using the Deformation-DIA apparatus at the X17B2 beamline of the NSLS (Upton, NY). Ten crystals were oriented in order to active either [100] slip alone or [001] slip alone in (010) plane, or both [100](001) and [001](100) systems together. Constant applied stress σ <300 MPa and specimen strain rates were monitored in situ using time-resolved x-ray diffraction and radiography, respectively, for a total of 27 investigated steady state conditions. The obtained rheological data were compared with data previously obtained in comparable T and σ conditions, but at room P, by Darot and Gueguen (1981, JGR, 86, 6219) for Fo100 and by Bai et al. (1991, JGR, 96, 2441) for San Carlos olivine. This new set of data confirms previous deformation data

  12. Decrease in red blood cell deformability is associated with a reduction in RBC-NOS activation during storage.

    PubMed

    Grau, Marijke; Friederichs, Petra; Krehan, Sebastian; Koliamitra, Christina; Suhr, Frank; Bloch, Wilhelm

    2015-07-16

    During storage, red blood cells (RBC) become more susceptible to hemolysis and it has also been shown that RBC deformability, which is influenced by RBC nitric oxide synthase (RBC-NOS) activity, decreases during blood storage while a correlation between these two parameters under storage conditions has not been investigated so far. Therefore, blood from 15 male volunteers was anticoagulated, leuko-reduced and stored as either concentrated RBC or RBC diluted in saline-adenine-glucose-mannitol (SAGM) for eight weeks at 4°C and results were compared to data obtained from freshly drawn blood. During storage, decrease of RBC deformability was related to increased mean cellular volume and increased cell lysis but also to a decrease in RBC-NOS activation. The changes were more pronounced in concentrated RBC than in RBC diluted in SAGM suggesting that the storage method affects the quality of blood. These data shed new light on mechanisms underlying the phenomenon of storage lesion and reveal that RBC-NOS activation and possibly nitric oxide production in RBC are key elements that are influenced by storage and in turn alter deformability. Further studies should therefore also focus on improving these parameters during storage to improve the quality of stored blood with respect to blood transfusion.

  13. Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front

    USGS Publications Warehouse

    Sohn, M.F.; Mahan, S.A.; Knott, J.R.; Bowman, D.D.

    2007-01-01

    Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

  14. Observations of Seafloor Deformation and Methane Venting within an Active Fault Zone Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Lundsten, E. M.; Paull, C. K.; Caress, D. W.; Thomas, H. J.; Brewer, P. G.; Vrijenhoek, R.; Lundsten, L.

    2013-12-01

    Detailed mapping surveys of the floor and flanks of the Santa Monica Basin, San Pedro Basin, and San Diego Trough were conducted during the past seven years using an Autonomous Underwater Vehicle (AUV) built and operated by MBARI specifically for seafloor mapping. The AUV collected data provide up to 1 m resolution multibeam bathymetric grids with a vertical precision of 0.15 m. Along with high-resolution multibeam, the AUV also collects chirp seismic reflection profiles. Structures within the uppermost 10-20 m of the seafloor, which in the surveys presented here is composed of recent sediment drape, can typically be resolved in the sub-bottom reflectors. Remotely operated vehicle (ROV) dives allowed for ground-truth observations and sampling within the surveyed areas. The objectives of these dives included finding evidence of recent seafloor deformation and locating areas where chemosynthetic biological communities are supported by fluid venting. Distinctive seafloor features within an active fault zone are revealed in unprecedented detail in the AUV generated maps and seismic reflection profiles. Evidence for recent fault displacements include linear scarps which can be as small as 20 cm high but traceable for several km, right lateral offsets within submarine channels and topographic ridges, and abrupt discontinuities in sub-bottom reflectors, which in places appear to displace seafloor sediments. Several topographic highs that occur within the fault zone appear to be anticlines related to step-overs in these faults. These topographic highs are, in places, topped with circular mounds that are up to 15 m high and have ~30° sloping sides. The crests of the topographic highs and the mounds both have distinctive rough morphologies produced by broken pavements of irregular blocks of methane-derived authigenic carbonates, and by topographic depressions, commonly more than 2 m deep. These areas of distinctive rough topography are commonly associated with living

  15. Active deformations of the Jura arc inferred by GPS and seismotectonics

    NASA Astrophysics Data System (ADS)

    Rabin, Mickael; Sue, Christian; Walpersdorf, Andrea

    2016-04-01

    The Jura Mountain is the most recent expression of the alpine orogeny. At the northern end of the western Alps, its recent deformation is still a matter of debates. GPS data available in the Jura bear witness of disagreement between studies, as interpretations vary from uplifted belt to arc-parallel extension (Walpersdorf, et al., 2006) and very slow horizontal movements. Moreover, the traditionally accepted model of an active collisional activity of the Jura, in the dynamic continuity of the Alps, rises up the matter of its geodynamic origin. Indeed, the European Alps are in a post-collisional regime characterized by isostatic-related extension and uplift driven by interaction between buoyancy forces and erosional dynamics (e.g. Sue et al. 2007; Champagnac, et al., 2007; Vernant, et al., 2013.). We present a reappraisal of published focal mechanisms combined with a new GPS solution over the entire arc and surrounding areas. Although the Jura presents a low seismic activity, 53 focal mechanisms over the Jura have been inverted in order to infer the current stress field. Anyhow, we tested several combinations of f.m. inversions, by structural zones, in order to test the regional stress stability. It appears that the current stress field is very stable all over the arc, and following our different sub-datasets. Indeed, the stress field shows a stable near horizontal NW-SE-oriented s1, associated to a NE-SW-oriented s3. Therefore, the structural arc of the Jura seems to have very low or no impact in terms of current stress. Complementarily, we present preliminary velocity and strain fields from a GPS network composed of 25 permanent stations implemented between 1998 and 2014 all around the Jura arc. Indeed, we also integrated the recent GPS-JURA station (OSU THETA Besançon), but they are still too young to accurately constrain the strain of the belt. Preliminary results exhibit very slow velocities across the arc in term of baselines evolution, with infra

  16. Crustal deformation

    NASA Astrophysics Data System (ADS)

    Larson, Kristine M.

    1995-07-01

    Geodetic measurements of crustal deformation provide direct tests of geophysical models which are used to describe the dynamics of the Earth. Although geodetic observations have been made throughout history, only in the last several hundred years have they been sufficiently precise for geophysical studies. In the 19th century, these techniques included leveling and triangulation. Approximately 25 years ago, trilateration measurements were initiated by the USGS (United States Geological Survey) to monitor active faults in the United States. Several years later, NASA (National Aeronautics and Space Administration) begin an effort to measure plate tectonic motions on a global scale, using space geodetic techniques, VLBI (Very Long Baseline Interferometry) and SLR (Satellite Laser Ranging). The period covered by this report to the IUGG, 1991-1994, was a transition period in the field of crustal deformation. Trilateration measurements (previously the backbone of measurements across plate boundaries in the western United States and Alaska) have been abandoned. This system was labor-intensive, involved highly trained crews to carry out the observations, and only measured the length between sites. In addition, NASA drastically cut the budgets for VLBI and SLR during this period. Fixed site VLBI systems are still operational, but mobile VLBI measurements in North America have ceased. SLR measurements continue on a global scale, but the remaining crustal deformation measurements are now being made with the Global Positioning System (GPS). Nonetheless, because of the time scales involved, older geodetic data (including leveling, triangulation, and trilateration) continue to be important for many geophysical studies.

  17. Volumetric deformation of live cells induced by pressure-activated cross-membrane ion transport.

    PubMed

    Hui, T H; Zhou, Z L; Qian, J; Lin, Y; Ngan, A H W; Gao, H

    2014-09-12

    In this work, we developed a method that allows precise control over changes in the size of a cell via hydrostatic pressure changes in the medium. Specifically, we show that a sudden increase, or reduction, in the surrounding pressure, in the physiologically relevant range, triggers cross-membrane fluxes of sodium and potassium ions in leukemia cell lines K562 and HL60, resulting in reversible volumetric deformation with a characteristic time of around 30 min. Interestingly, healthy leukocytes do not respond to pressure shocks, suggesting that the cancer cells may have evolved the ability to adapt to pressure changes in their microenvironment. A model is also proposed to explain the observed cell deformation, which highlights how the apparent viscoelastic response of cells is governed by the microscopic cross-membrane transport.

  18. Volumetric Deformation of Live Cells Induced by Pressure-Activated Cross-Membrane Ion Transport

    NASA Astrophysics Data System (ADS)

    Hui, T. H.; Zhou, Z. L.; Qian, J.; Lin, Y.; Ngan, A. H. W.; Gao, H.

    2014-09-01

    In this work, we developed a method that allows precise control over changes in the size of a cell via hydrostatic pressure changes in the medium. Specifically, we show that a sudden increase, or reduction, in the surrounding pressure, in the physiologically relevant range, triggers cross-membrane fluxes of sodium and potassium ions in leukemia cell lines K562 and HL60, resulting in reversible volumetric deformation with a characteristic time of around 30 min. Interestingly, healthy leukocytes do not respond to pressure shocks, suggesting that the cancer cells may have evolved the ability to adapt to pressure changes in their microenvironment. A model is also proposed to explain the observed cell deformation, which highlights how the apparent viscoelastic response of cells is governed by the microscopic cross-membrane transport.

  19. Preliminary results of ESA Category-1 Project 5834 "Application of DInSAR technique to areas of active ground deformations"

    NASA Astrophysics Data System (ADS)

    Massa, B.; D'Auria, L.

    2009-04-01

    We have established a processing chain of Synthetic Aperture Radar (SAR) data for identification and parametrisation of deformation sources in areas of active ground deformation (e.g. seismogenic areas, volcanic districts). SAR data from European Space Agency (ESA) satellites ERS-2 and ENVISAT are used. SAR and InSAR data processing LEVEL 0 SAR data are focussed to Single Look Complex (SLC) through ROI_PAC (Copyright 2002-2008, Caltech/Jet Propulsion Laboratory). We perform an advanced data processing using Doris (Kampes and Usai, 1999) a single program that can do most common steps of the interferometric radar processing starting from SLC data to generation of interferometric products and geocoding. Unwrapping of interferometric phase is performed using the public domain software snaphu (Chen and Zebker, 2001). Modeling of deformation sources We propose a novel inversion approach base on non-linear inversion. The forward modeling is provided by the semi-analytic deformation model for point sources and finite faults. The parameters of the fault (center position, width, height, rake and seismic moment) are inverted using a combination of non-linear optimization algorithms (as Monte-Carlo, Nelder&Mead Simplex and Simulated Annealing). The misfit function defined for the optimization is based on the L2 norm of the error weighted by the coherence of the considered spatial point. Test datasets To test our modeling procedure we chose three different study areas, refer to mainly strike-slip seismogenic sources with different orientation to respect satellite Line Of Sight (LOS): December 26 2003 Iranian earthquake (Bam e.), data from both ascending and descending passes of ENVISAT ASAR narrow swath IS2 (RAW and SLCs); August 17 1999 Turkey earthquake (Izmit e.), data from both ascending and descending passes of ERS-2 AMI SAR (SLCs); June 17-21 2000 Iceland earthquakes, data from both ascending and descending passes of ERS-2 AMI SAR (SLCs). Tests carried over real

  20. Persistent inflation at Aira caldera accompanying explosive activity at Sakurajima volcano: Constraining deformation source parameters from Finite Element inversions

    NASA Astrophysics Data System (ADS)

    Hickey, James; Gottsmann, Jo; Iguchi, Masato; Nakamichi, Haruhisa

    2015-04-01

    Aira caldera is located within Kagoshima Bay at the southern end of Kyushu, Japan. Sakurajima is an active post-caldera andesitic stratovolcano that sits on the caldera's southern rim. Despite frequent Vulcanian-type explosive activity, the area is experiencing continued uplift at a maximum rate of approximately 1.5 cm/yr with a footprint of 40 km, indicating that magma is being supplied faster than it is erupted. This is of particular concern as the amplitude of deformation is approaching the level inferred prior to the 1914 VEI 4 eruption. Using GPS data from 1996 - 2007 we explore causes for the uplift. To solve for the optimum deformation source parameters we use an inverse Finite Element method accounting for three-dimensional material heterogeneity (inferred from seismic tomography) and the surrounding topography of the region. The same inversions are also carried out using Finite Element models that incorporate simplified homogeneous or one-dimensional subsurface material properties, with and without topography. Results from the comparison of the six different models show statistically significant differences in the inferred deformation sources. This indicates that both subsurface heterogeneity and surface topography are essential in geodetic modelling to extract the most realistic deformation source parameters. The current best-fit source sits within a seismic low-velocity zone in the north-east of the caldera at a depth of approximately 14 km with a volume increase of 1.2 x 108 m3. The source location underlies a region of active underwater fumaroles within the Wakamiko crater and differs significantly from previous analytical modelling results. Seismic data further highlights areas of high seismic attenuation as well as large aseismic zones, both of which could allude to inelastic behaviour and a significant heat source at depth. To integrate these observations, subsequent forward Finite Element models will quantify the importance of rheology and

  1. Active intraplate deformation as geodynamic responses to oblique shallow subduction of a flat slab: example from central and southwest Japan

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tatsuya; Sato, Hiroshi

    2015-04-01

    Subduction of a flat slab has been recognized as one of the primary driving mechanism of wide intracontinental subsidence farther away from the subduction leading edge in many subduction margins. In most cases, however, quantitative and qualitative limitations on chronological constraints prevent comprehensive understanding of these geodynamic linkages. In this study, we show distinct, geologic and seismic evidence for spatial and temporal correlation between plate subduction and intercontinental deformation, mainly driven by dynamic interaction between subducting Philippine Sea (PHS) plate and overriding continental crusts of central and southwest Japan (Eurasian plate) along the Nankai-Tonankai subduction zone since Pliocene. Based on analyses of Pliocene to Pleistocene tectonic histories by use of rich dataset of Neogene stratigraphy, drainage network evolution, and shallow to deep seismic reflection profiles, depocenters of wide sedimentary basins and active thrusting have migrated northward since ca. 5 Ma to present from forearc to backarc of the southwest Japan arc. Median tectonic line, active dextral strike-slip fault as a forearc sliver along the Nankai, is located north of the upward extension of the downdip limit of the interseismic locked zone. Southwest Japan north of the MTL, underlain by the subducting slab with steady state slip (Nakanishi et al., 2002; Kodaira et al., 2004), appears tectonically less inactive than central Japan and has behaved as a less deformed rigid block. Contrastingly, Quaternary active intraplate deformation has been prominent north of the inactive MTL above a shallow flat segment of the PHS plate along the Tonankai. Deep seismic reflection profile images upward corrugated very shallow PHS slab being contact with continental lower crust beneath actively deforming area. We interpreted temporal and spatial correlation of oblique subduction of the shallow and flat, corrugated PHS slab as an essential mechanical role to enhance

  2. Correction of an active space telescope mirror using a deformable mirror in a woofer-tweeter configuration

    NASA Astrophysics Data System (ADS)

    Allen, Matthew R.; Kim, Jae Jun; Agrawal, Brij N.

    2016-04-01

    The Naval Postgraduate School's segmented mirror telescope (SMT) was developed using prototype silicon carbide active hybrid mirror technology to demonstrate lower cost and rapid manufacture of primary mirror segments for a space telescope. The developmental mirror segments used too few actuators limiting the ability to adequately correct the surface figure error. To address the unintended shortfall of the developmental mirrors, a deformable mirror is added to the SMT and control techniques are developed. The control techniques are similar to woofer-tweeter adaptive optics, where the SMT segment represents the woofer and the deformable mirror represents the tweeter. The optical design of an SMT woofer-tweeter system is presented, and the impacts of field angle magnification on the placement and size of the deformable mirror are analyzed. A space telescope woofer-tweeter wavefront control technique is proposed using a global influence matrix and closed-loop constrained minimization controller. The control technique simultaneously manipulates the woofer and tweeter mirrors. Simulation and experimental results demonstrate a significant improvement in wavefront error of the primary mirror and the control technique shows significant wavefront error improvement compared to sequentially controlling the woofer and tweeter mirrors.

  3. dMODELS: A MATLAB software package for modeling crustal deformation near active faults and volcanic centers

    NASA Astrophysics Data System (ADS)

    Battaglia, Maurizio; Cervelli, Peter F.; Murray, Jessica R.

    2013-03-01

    We have developed a MATLAB software package for the most common models used to interpret deformation measurements near faults and active volcanic centers. The emphasis is on analytical models of deformation that can be compared with data from the Global Positioning System (GPS), InSAR, tiltmeters and strainmeters. Source models include pressurized spherical, ellipsoidal and sill-like magma chambers in an elastic, homogeneous, flat half-space. Dikes and faults are described following the mathematical notation for rectangular dislocations in an elastic, homogeneous, flat half-space. All the expressions have been checked for typographical errors that might have been present in the original literature, extended to include deformation and strain within the Earth's crust (as opposed to only the Earth's surface) and verified against finite element models. A set of GPS measurements from the 2006 eruption at Augustine Volcano (Alaska) is used to test the software package. The results show that the best fit source to the GPS data is a spherical intrusion (ΔV=5×10 km3), about 880 m beneath the volcano's summit.

  4. Evaluation of stiffness and plastic deformation of active ceramic self-ligating bracket clips after repetitive opening and closure movements

    PubMed Central

    Carneiro, Grace Kelly Martins; Roque, Juliano Alves; Segundo, Aguinaldo Silva Garcez; Suzuki, Hideo

    2015-01-01

    OBJECTIVE: The aim of this study was to assess whether repetitive opening and closure of self-ligating bracket clips can cause plastic deformation of the clip. METHODS: Three types of active/interactive ceramic self-ligating brackets (n = 20) were tested: In-Ovation C, Quicklear and WOW. A standardized controlled device performed 500 cycles of opening and closure movements of the bracket clip with proper instruments and techniques adapted as recommended by the manufacturer of each bracket type. Two tensile tests, one before and one after the repetitive cycles, were performed to assess the stiffness of the clips. To this end, a custom-made stainless steel 0.40 x 0.40 mm wire was inserted into the bracket slot and adapted to the universal testing machine (EMIC DL2000), after which measurements were recorded. On the loading portion of the loading-unloading curve of clips, the slope fitted a first-degree equation curve to determine the stiffness/deflection rate of the clip. RESULTS: The results of plastic deformation showed no significant difference among bracket types before and after the 500 cycles of opening and closure (p = 0.811). There were significant differences on stiffness among the three types of brackets (p = 0.005). The WOW bracket had higher mean values, whereas Quicklear bracket had lower values, regardless of the opening/closure cycle. CONCLUSION: Repetitive controlled opening and closure movements of the clip did not alter stiffness or cause plastic deformation. PMID:26352844

  5. Effect of Tungsten on Primary Creep Deformation and Minimum Creep Rate of Reduced Activation Ferritic-Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Vanaja, J.; Laha, Kinkar; Mathew, M. D.

    2014-10-01

    Effect of tungsten on transient creep deformation and minimum creep rate of reduced activation ferritic-martensitic (RAFM) steel has been assessed. Tungsten content in the 9Cr-RAFM steel has been varied between 1 and 2 wt pct, and creep tests were carried out over the stress range of 180 and 260 MPa at 823 K (550 °C). The tempered martensitic steel exhibited primary creep followed by tertiary stage of creep deformation with a minimum in creep deformation rate. The primary creep behavior has been assessed based on the Garofalo relationship, , considering minimum creep rate instead of steady-state creep rate . The relationships between (i) rate of exhaustion of transient creep r' with minimum creep rate, (ii) rate of exhaustion of transient creep r' with time to reach minimum creep rate, and (iii) initial creep rate with minimum creep rate revealed that the first-order reaction-rate theory has prevailed throughout the transient region of the RAFM steel having different tungsten contents. The rate of exhaustion of transient creep r' and minimum creep rate decreased, whereas the transient strain ɛ T increased with increase in tungsten content. A master transient creep curve of the steels has been developed considering the variation of with . The effect of tungsten on the variation of minimum creep rate with applied stress has been rationalized by invoking the back-stress concept.

  6. Active deformation and engineering analysis of CFRP mirror of various lay-up sequences within quasi-isotropic laminates

    NASA Astrophysics Data System (ADS)

    Zeng, Chunmei; Yu, Xia; Guo, Peiji

    2014-08-01

    A regularization stiffness coefficient method was verified further to optimize lay-up sequences of quasi-isotropic laminates for carbon fiber reinforced polymer (CFRP) composite mirrors. Firstly, the deformation due to gravity of 1G and temperature difference of 20-100°C and the modal were analyzed by finite element method (FEM). Secondly, the influence of angle error of ply stacking on quasi-isotropic of bending stiffness was evaluated. Finally, an active support system of 49 actuators in circular arrangement is designed for a 500mm CFRP mirror, and its goal is to deform the spherical CFRP mirror to a parabolic. Therefore, the response functions of the actuators were gotten, and the surface form errors and stresses were calculated and analyzed. The results show that the CFRP mirrors designed by the method have a better symmetrical bending deformation under gravity and thermal load and a higher fundamental frequency, and the larger n the better symmetry (for π/n quasi-isotropic laminates); the method reduces the sensitivity to misalignment of ply orientation for symmetric bending, and the mirror's maximum von Mises stress and maximum shear stress are less compared to those laminates not optimized in lay-up sequence.

  7. Mechanics of Magnetostrictive Thin Film Deformation and its Application in Active X-ray Optics

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli

    High quality imaging system of telescopes in astronomy requires innovations to remove or correct the mid-spatial frequency (MSF) ripples on the mirror surface of lightweight optics. When the telescope is sent to the space, its launch mass is the key point to limit its collecting area. Therefore, the lightweight optics (100-150 mum thick electroplated nickel/cobalt, or 200-400 mum thick glass) is considered to be employed. However, the surface profile of the thin optical surface can't be polished to extremely high accuracy. Instead, the profile is expected to be corrected by applying voltage or magnetic field to drive the coating of smart materials (piezo or magnetostrictive materials) on the back side of the mirrors. During the process, the surface profile correction by the local stress on the 2-d surface is challenging. Both the measurements and the theoretical prediction of the surface profiles after correction are investigated. As a first step in the development of tools to predict the deformation of the coated glass strip samples (20x5x0.1 mm), one commercial magnetically smart material (MSM) was deposited on the samples by the magnetron sputtering method. One experimental setup was established to measure the deflections of these coated samples under an external magnetic field by Zygo NewView white light interferometry (WLI). These deflections agreed well with the results from the developed analytical and numerical analysis under various magnetic field strengths. In the further research, more efforts were made to analyze the full three-dimensional deformation behavior of MSM thin films on a square glass sample (50x50x0.2 mm). With the magnetic field applied, the 2-d surface profile of the coated glass sample was measured by WLI. To better study the deformation of the sample coated with MSMs, a finite element method (FEM) and a theoretical model were developed to predict the deformation of the sample with local misfit strains. The results calculated form the FEM

  8. Sequential growth of deformation bands in carbonate grainstones in the hangingwall of an active growth fault: Implications for deformation mechanisms in different tectonic regimes

    NASA Astrophysics Data System (ADS)

    Rotevatn, Atle; Thorsheim, Elin; Bastesen, Eivind; Fossmark, Heidi S. S.; Torabi, Anita; Sælen, Gunnar

    2016-09-01

    Deformation bands in porous sandstones have been extensively studied for four decades, whereas comparatively less is known about deformation bands in porous carbonate rocks, particularly in extensional settings. Here, we investigate porous grainstones of the Globigerina Limestone Formation in Malta, which contain several types of deformation bands in the hangingwall of the Maghlaq Fault: (i) bed-parallel pure compaction bands (PCB); (ii) pressure solution-dominated compactive shear bands (SCSB) and iii) cataclasis-dominated compactive shear bands (CCSB). Geometric and kinematic analyses show that the bands formed sequentially in the hangingwall of the evolving Maghlaq growth fault. PCBs formed first due to fault-controlled subsidence and vertical loading; a (semi-)tectonic control on PCB formation is thus documented for the first time in an extensional setting. Pressure solution (dominating SCSBs) and cataclasis (dominating CCSBs) appear to have operated separately, and not in concert. Our findings therefore suggest that, in some carbonate rocks, cataclasis within deformation bands may develop irrespective of whether pressure solution processes are involved. We suggest this may be related to stress state, and that whereas pressure solution is a significant facilitator of grain size reduction in contractional settings, grain size reduction within deformation bands in extensional settings is less dependent on pressure solution processes.

  9. Front Matter: Volume 8454

    NASA Astrophysics Data System (ADS)

    SPIE, Proceedings of

    2012-05-01

    This PDF file contains the front matter associated with SPIE Proceedings Volume 8454, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

  10. Imaging active faults in a region of distributed deformation from joint focal mechanism and hypocenter clustering: Application to western Iberia

    NASA Astrophysics Data System (ADS)

    Custodio, S.; Lima, V.; Vales, D.; Carrilho, F.; Cesca, S.

    2015-12-01

    Mainland Portugal, on the SW edge of the European continent, is located directly north of the boundary between the Eurasian and Nubian plates. It lies in a region of slow lithospheric deformation, which has generated some of the largest earthquakes in Europe, both intraplate (mainland) and interplate (offshore). The seismicity of mainland Portugal and its adjacent offshore has been repeatedly classified as diffuse. We analyse the instrumental earthquake catalog for western Iberia, enriched with data from recent dense broadband deployments. We show that although the plate boundary south of Portugal is diffuse, in that deformation is accommodated along several distributed faults rather than along one long linear plate boundary, the seismicity itself is not diffuse. Rather, when located using high quality data, earthquakes collapse into well-defined clusters and lineations. We then present a new joint focal mechanism and hypocenter cluster algorithm that is able to extract coherent information between hypocenter locations and focal mechanisms. We apply the method to the Azores-western Mediterranean region, with emphasis on western Iberia. In addition to identifying well-known seismo-tectonic features, the joint clustering algorithm identifies eight new clusters of earthquakes with a good match between the directions of epicentre lineations and focal mechanism fault planes. These clusters may signal single active faults or wider fault zones accommodating a consistent type of faulting. Mainland Portugal is dominated by strike-slip faulting, consistent with the NNE-SSW and WNW-ESE oriented lineations. The region offshore SW Iberia displays clusters that are either predominantly strike-slip or reverse, indicating slip partitioning. This work shows that the study of low-magnitude earthquakes using dense seismic deployments is a powerful tool to study lithospheric deformation in slowly deforming regions, where high-magnitude earthquakes occur with long recurrence intervals.

  11. Active crustal deformation of the El Salvador Fault Zone (ESFZ) using GPS data: Implications in seismic hazard assessment

    NASA Astrophysics Data System (ADS)

    Staller, Alejandra; Benito, Belen; Jesús Martínez-Díaz, José; Hernández, Douglas; Hernández-Rey, Román; Alonso-Henar, Jorge

    2014-05-01

    El Salvador, Central America, is part of the Chortis block in the northwestern boundary of the Caribbean plate. This block is interacting with a diffuse triple junction point with the Cocos and North American plates. Among the structures that cut the Miocene to Pleistocene volcanic deposits stands out the El Salvador Fault Zone (ESFZ): It is oriented in N90º-100ºE direction, and it is composed of several structural segments that deform Quaternary deposits with right-lateral and oblique slip motions. The ESFZ is seismically active and capable of producing earthquakes such as the February 13, 2001 with Mw 6.6 (Martínez-Díaz et al., 2004), that seriously affected the population, leaving many casualties. This structure plays an important role in the tectonics of the Chortis block, since its motion is directly related to the drift of the Caribbean plate to the east and not with the partitioning of the deformation of the Cocos subduction (here not coupled) (Álvarez-Gómez et al., 2008). Together with the volcanic arc of El Salvador, this zone constitutes a weakness area that allows the motion of forearc block toward the NW. The geometry and the degree of activity of the ESFZ are not studied enough. However their knowledge is essential to understand the seismic hazard associated to this important seismogenic structure. For this reason, since 2007 a GPS dense network was established along the ESFZ (ZFESNet) in order to obtain GPS velocity measurements which are later used to explain the nature of strain accumulation on major faults along the ESFZ. The current work aims at understanding active crustal deformation of the ESFZ through kinematic model. The results provide significant information to be included in a new estimation of seismic hazard taking into account the major structures in ESFZ.

  12. The Plio-Pleistocene evolution of the Southern Middle Atlas Fault Zone (SMAFZ) front of Morocco

    NASA Astrophysics Data System (ADS)

    Laville, E.; Delcaillau, B.; Charroud, M.; Dugué, O.; Ait Brahim, L.; Cattaneo, G.; Deluca, P.; Bouazza, A.

    2007-06-01

    The South Middle Atlas front constitutes a northeast-trending shear zone, located north of the Neogene Missour basin and east of the Taza Guercif basin. This paper analyses the Southern Middle Atlas Fault Zone (SMAFZ) deformation since the Pliocene. The set of structures observed suggests that reverse and thrust faulting along the central part of the SMAFZ are combined with left-lateral slip along N S striking faults of its south-western termination and right-lateral faulting along E NE striking faults of the east northeast termination. Thrusts and oblique thrust-related anticlines of the two lateral ramps partly accommodate north-west directed motion of the African plate. The Thrusts probably resulted from rejuvenation of Jurassic normal faults; they were active during the Upper Miocene Pliocene and the Pleistocene. The geometries of positive inversion structures and buttressing effects are clearly dependent on the geometry and sedimentology of the original basin-controlling fault system and on the presence of a décollement level. Field mapping is integrated with Landsat imagery and a digital elevation model to investigate the morphotectonic evolution of the south-eastern range front of the Middle Atlas. Geomorphological features provide significant information on the processes that govern lateral propagation of active anticlines. Both suggest that the deformation front may have been active since Pliocene.

  13. Unimorph deformable mirror for space telescopes: design and manufacturing.

    PubMed

    Rausch, Peter; Verpoort, Sven; Wittrock, Ulrich

    2015-07-27

    Large space telescopes made of deployable and lightweight structures suffer from aberrations caused by thermal deformations, gravitational release, and alignment errors which occur during the deployment procedure. An active optics system would allow on-site correction of wave-front errors, and ease the requirements on thermal and mechanical stability of the optical train. In the course of a project funded by the European Space Agency we have developed and manufactured a unimorph deformable mirror based on piezoelectric actuation. The mirror is able to work in space environment and is designed to correct for large aberrations of low order with high surface fidelity. This paper discusses design, manufacturing and performance results of the deformable mirror. PMID:26367605

  14. Unimorph deformable mirror for space telescopes: design and manufacturing.

    PubMed

    Rausch, Peter; Verpoort, Sven; Wittrock, Ulrich

    2015-07-27

    Large space telescopes made of deployable and lightweight structures suffer from aberrations caused by thermal deformations, gravitational release, and alignment errors which occur during the deployment procedure. An active optics system would allow on-site correction of wave-front errors, and ease the requirements on thermal and mechanical stability of the optical train. In the course of a project funded by the European Space Agency we have developed and manufactured a unimorph deformable mirror based on piezoelectric actuation. The mirror is able to work in space environment and is designed to correct for large aberrations of low order with high surface fidelity. This paper discusses design, manufacturing and performance results of the deformable mirror.

  15. High resolution deformation measurements at active volcanoes: a new remote sensing technology

    NASA Astrophysics Data System (ADS)

    Hort, M. K.; Scharff, L.; Gerst, A.; Meier, K.; Falk, S.; Peters, G.; Ripepe, M.

    2013-12-01

    It is known from observations at different volcanoes using ULP seismic observations that the volcanic edifice deforms slightly prior to an eruption. It can be expected that immediately prior to an eruption the largest deformation should occur in the vicinity of the vent. However, placing instruments at the vent is impossible as they will be destroyed during an eruption. Here we present new, high temporal resolution (up to 300Hz) deformation measurement that utilizes the phase information of a frequency modulated Doppler radar system. We decompose the Doppler signal into two parts, one part which allows us to measure speeds significantly above 0.5m/s (i.e. the movement of volcanic ash and clasts). The other part utilizes the slow phase changes of the signal reflected from non-moving objects, i.e. the volcanic edifice. This signal is used to measure very slow and longer term deformations, which are the main subject of this study. The method has been tested measuring the displacement of high rise buildings during strong winds. It can be shown that displacements down to 50 μm can be resolved without a problem. We apply this method to different data sets collected at Stromboli volcano, Italy, as well as Santiaguito volcano, Guatemala. At Stromboli we observed the NE crater once in 2008 and once in 2011. During both campaigns we observe on average a displacement between 1 and 5mm before different eruptions. This displacement can be interpreted as a widening of the conduit prior to an eruption. In a couple of cases even an oscillatory movement is observed with frequencies of about 0.5Hz. Finite element modeling of the rise of a pressurized slug indicates that deformations at the crater rim on the order of a 1mm or less are certainly reasonable. In the case of Santiaguito volcano prior to an eruption we observe a pre eruptive displacement 5-15mm and after the end of an eruption a displacement of up to 1m before the next eruption occurs. This can be interpreted as in

  16. Numerical simulation and experimental validation of the large deformation bending and folding behavior of magneto-active elastomer composites

    NASA Astrophysics Data System (ADS)

    Sheridan, Robert; Roche, Juan; Lofland, Samuel E.; vonLockette, Paris R.

    2014-09-01

    This work seeks to provide a framework for the numerical simulation of magneto-active elastomer (MAE) composite structures for use in origami engineering applications. The emerging field of origami engineering employs folding techniques, an array of crease patterns traditionally on a single flat sheet of paper, to produce structures and devices that perform useful engineering operations. Effective means of numerical simulation offer an efficient way to optimize the crease patterns while coupling to the performance and behavior of the active material. The MAE materials used herein are comprised of nominally 30% v/v, 325 mesh barium hexafarrite particles embedded in Dow HS II silicone elastomer compound. These particulate composites are cured in a magnetic field to produce magneto-elastic solids with anisotropic magnetization, e.g. they have a preferred magnetic axis parallel to the curing axis. The deformed shape and/or blocked force characteristics of these MAEs are examined in three geometries: a monolithic cantilever as well as two- and four-segment composite accordion structures. In the accordion structures, patches of MAE material are bonded to a Gelest OE41 unfilled silicone elastomer substrate. Two methods of simulation, one using the Maxwell stress tensor applied as a traction boundary condition and another employing a minimum energy kinematic (MEK) model, are investigated. Both methods capture actuation due to magnetic torque mechanisms that dominate MAE behavior. Comparison with experimental data show good agreement with only a single adjustable parameter, either an effective constant magnetization of the MAE material in the finite element models (at small and moderate deformations) or an effective modulus in the minimum energy model. The four-segment finite element model was prone to numerical locking at large deformation. The effective magnetization and modulus values required are a fraction of the actual experimentally measured values which suggests a

  17. Haglund's Deformity

    MedlinePlus

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

  18. Railway deformation detected by DInSAR over active sinkholes in the Ebro Valley evaporite karst, Spain

    NASA Astrophysics Data System (ADS)

    Galve, J. P.; Castañeda, C.; Gutiérrez, F.

    2015-06-01

    Previously not measured subsidence on railway tracks was detected using DInSAR displacement maps produced for the central sector of Ebro Valley (NE Spain). This area is affected by evaporite karst and the analyzed railway corridors traverse active sinkholes that produce deformations in these infrastructures. One of the railway tracks affected by slight settlements corresponds to the Madrid-Barcelona high-speed line, a transport infrastructure highly vulnerable to ground deformation processes. Our analysis based on DInSAR measurements and geomorphological surveys indicate that this line show dissolution-induced subsidence and compaction of anthropogenic deposits (infills and embankments). By using DInSAR techniques, it was also measured the significant subsidence related to the activity of sinkholes in the Castejón-Zaragoza conventional railway line. Thus, this study demonstrate that DInSAR velocity maps coupled with detailed geomorphological surveys may help in the identification of the sectors of railway tracks that may compromise the safety of travellers.

  19. Active deformation in Zagros-Makran transition zone inferred from GPS measurements

    NASA Astrophysics Data System (ADS)

    Bayer, R.; Chery, J.; Tatar, M.; Vernant, Ph.; Abbassi, M.; Masson, F.; Nilforoushan, F.; Doerflinger, E.; Regard, V.; Bellier, O.

    2006-04-01

    The Bandar Abbas-Strait of Hormuz zone is considered as a transition between the Zagros collision and the Makran oceanic subduction. We used GPS network measurements collected in 2000 and 2002 to better understand the distribution of the deformation between the collision zone and the Makran subduction. Analysing the GPS velocities, we show that transfer of the deformation is mainly accommodated along the NNW-SSE-trending reverse right-lateral Zendan-Minab-Palami (ZMP) fault system. The rate is estimated to 10 +/- 3 mm yr-1 near the faults. Assuming that the ZMP fault system transfers the motion between the Makran-Lut Block and the Arabian plate, we estimate to 15 mm yr-1 and 6 mm yr-1, respectively, the dextral strike-slip and shortening components of the long-term transpressive displacement. Our geodetic measurements suggest also a 10-15 km locking depth for the ZMP fault system. The radial velocity pattern and the orientation of compressive strain axes around the straight of Hormuz is probably the consequence of the subducting Musandam promontory. The N-S Jiroft-Sabzevaran (JS) fault system prolongates southwards the dextral shear motion of the Nayband-Gowk (NG) fault system at an apparent rate of 3.1 +/- 2.5 mm yr-1. The change from strong to weak coupling for underthrusting the Arabian plate beneath the Zagros (strong) and the Makran (weak) may explain the dextral motion along the ZMP, JS/NG and Neh-Zahedan fault systems which transfer the convergence from a broad zone in the western Iran (Zagros, Tabriz fault system, Alborz, Caucasus and Caspian sea surroundings) to Makran subduction.

  20. Fluvial Record of Active Deformation Along the Canyon River Fault in the Wynoochee River Valley, WA

    NASA Astrophysics Data System (ADS)

    Delano, J.; Amos, C. B.; Loveless, J. P.; Rittenour, T. M.

    2015-12-01

    Ongoing uplift of the Olympic Peninsula of Washington State represents unknown contributions from Cascadia subduction zone processes, including earthquakes, interseismic deformation, aseismic slow slip events, and north-south shortening of the North American plate focused on upper plate faults. The relationship between upper plate faults and Cascadia subduction is poorly understood, as is the seismic hazard posed by these structures to the greater Puget Sound region. The Wynoochee River is a south-flowing drainage in the southern Olympic Mountains bisected by a previously uncharacterized section of the Canyon River reverse fault. In this study we utilize high-resolution aerial lidar and optically stimulated luminescence (OSL) dating of offset fluvial terraces to determine the kinematics and slip rate of the Canyon River fault over the late Quaternary. In combination with surficial geologic mapping and differential GPS surveys of terrace straths observed in the field, we also determine incision rates along the Wynoochee River from OSL dates. Our mapping reveals eight generations of fluvial and glaciofluvial terraces, with twenty-one pending ages from OSL sampling of fluvial sands intercalated with outwash and river gravels. Additionally, we compare our slip rate results with a boundary element model, estimating the stress on the Canyon River fault over the recent decades, as constrained by GPS data from the Cascadia subduction zone. Preliminary results indicate that the Canyon River fault is a long-lived feature with south-side-up and left-lateral displacement. Taken together, our results enable comparison of deformation rates constrained by short-term, geodetic data with those acting over longer-term geologic time scales.

  1. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  2. Observing active deformation of volcanoes in North America: Geodetic data from the Plate Boundary Observatory and associated networks

    NASA Astrophysics Data System (ADS)

    Puskas, C. M.; Phillips, D. A.; Mattioli, G. S.; Meertens, C. M.; Hodgkinson, K. M.; Crosby, C. J.; Enders, M.; Feaux, K.; Mencin, D.; Baker, S.; Lisowski, M.; Smith, R. B.

    2013-12-01

    The EarthScope Plate Boundary Observatory (PBO), operated by UNAVCO, records deformation of the geologically diverse North America western plate boundary, with subnetworks of instruments concentrated at selected active and potentially active volcanoes. These sensors record deformation and earthquakes and allow monitoring agencies and researchers to analyze changes in ground motion and seismicity. The intraplate volcanoes at Yellowstone and Long Valley are characterized by uplift/subsidence cycles, high seismicity, and hydrothermal activity but there have been no historic eruptions at either volcano. PBO maintains dense GPS networks of 20-25 stations at each of these volcanoes, with an additional 5 boreholes at Yellowstone containing tensor strainmeters, short-period seismometers, and borehole tiltmeters. Subduction zone volcanoes in the Aleutian Arc have had multiple historic eruptions, and PBO maintains equipment at Augustine (8 GPS), Akutan (8 GPS, 4 tiltmeters), and Unimak Island (14 GPS, 8 tiltmeters). The Unimak stations are at the active Westdahl and Shishaldin edifices and the nearby, inactive Isanotski volcano. In the Cascade Arc, PBO maintains networks at Mount St. Helens (15 GPS, 4 borehole strainmeters and seismometers, 8 borehole tiltmeters), Shasta (7 GPS, 1 borehole strainmeter and seismometer), and Lassen Peak (8 GPS). Data from many of these stations in the Pacific Northwest and California are also provided as realtime streams of raw and processed data. Real-time GPS data, along with high-rate GPS data, will be an important new resource for detecting and studying future rapid volcanic deformation events and earthquakes. UNAVCO works closely with the USGS Volcano Hazards Program, archiving data from USGS GPS stations in Alaska, Cascadia, and Long Valley. The PBO and USGS networks combined provide more comprehensive coverage than PBO alone, particularly of the Cascade Arc, where the USGS maintains a multiple instruments near each volcano. Ground

  3. Creep Deformation and Rupture Behavior of Single- and Dual-Pass 316LN Stainless-Steel-Activated TIG Weld Joints

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Vasudevan, M.; Ganesan, V.; Parameswaran, P.; Laha, K.; Bhaduri, A. K.

    2016-06-01

    Creep deformation and rupture behavior of single-pass and dual-pass 316LN stainless steel (SS) weld joints fabricated by an autogenous activated tungsten inert gas welding process have been assessed by performing metallography, hardness, and conventional and impression creep tests. The fusion zone of the single-pass joint consisted of columnar zones adjacent to base metals with a central equiaxed zone, which have been modified extensively by the thermal cycle of the second pass in the dual-pass joint. The equiaxed zone in the single-pass joint, as well as in the second pass of the dual-pass joint, displayed the lowest hardness in the joints. In the dual-pass joint, the equiaxed zone of the first pass had hardness comparable to the columnar zone. The hardness variations in the joints influenced the creep deformation. The equiaxed and columnar zone in the first pass of the dual-pass joint was more creep resistant than that of the second pass. Both joints possessed lower creep rupture life than the base metal. However, the creep rupture life of the dual-pass joint was about twofolds more than that of the single-pass joint. Creep failure in the single-pass joint occurred in the central equiaxed fusion zone, whereas creep cavitation that originated in the second pass was blocked at the weld pass interface. The additional interface and strength variation between two passes in the dual-pass joint provides more restraint to creep deformation and crack propagation in the fusion zone, resulting in an increase in the creep rupture life of the dual-pass joint over the single-pass joint. Furthermore, the differences in content, morphology, and distribution of delta ferrite in the fusion zone of the joints favors more creep cavitation resistance in the dual-pass joint over the single-pass joint with the enhancement of creep rupture life.

  4. Active crustal deformation in the Jalisco block, Mexico: evidence for a great historical earthquake in the 16th century

    NASA Astrophysics Data System (ADS)

    Suárez, Gerardo; García-Acosta, Virginia; Gaulon, Roland

    1994-06-01

    On December 27th, 1568, a large earthquake occurred to the southwest of Guadalajara, Mexico, near the northeastern corner of the Jalisco block, in an area where no great earthquakes have been reported before. It caused heavy damage in the region where the Colima and Tepic-Zacoalco grabens intersect. Many churches, houses and convents in the neighboring towns collapsed and severe deformation of the ground was observed in the area. Landslides apparently dammed the Ameca River for several days and the opening of large cracks was reported in the lowlands. The flow of natural springs and the level of Lake Zacoalco changed dramatically after the earthquake. All of these reports strongly suggest that a local fault was the source of this large and destructive earthquake. Based on the intensity data inferred from the historical reports, the 1568 event is perhaps the largest earthquake to date in the Trans-Mexican Volcanic Belt. Compared to other well documented, large earthquakes that occurred in the volcanic belt in 1875, 1912 and 1920, the magnitude appears to be greater than 7.0 ( MW). The Jalisco block is presumed to be rifting away from the North American plate. The Colima and Tepic-Zacoalco grabens, which bound the Jalisco block to the east and north, respectively, are apparently the boundaries where rifting is taking place in a complex and highly faulted environment. Based on the data available, it is impossible to identify the specific fault ruptured during the earthquake unequivocally. However, the occurrence of this large event in 1568 confirms that active deformation is still taking place in the Jalisco block. The apparently long recurrence times of these large events suggest that tectonic deformation is slow.

  5. Observation and interpretation of thermal instabilities at the front face of actively cooled limiters in TORE-SUPRA

    SciTech Connect

    Guilhem, D.; Hogan, J.T.; Mitteau, R.; Phillips, V.

    1995-12-01

    In TORE-SUPRA, actively cooled modular limiters (time constant = 2 s) covered with carbon have been used to exhaust the convective heat flux continuously up to 700 kW steady state (design value) without thermal instability, i.e., 4.5 MW/m{sup 2} on average. Steady state surface temperatures in the range 600 C (with 1.45 MW of Lower Hybrid waves) were routinely obtained. However, sudden surface temperature excursions from 600 C to 1,900 C, called ``super-brilliances``, were observed during ohmic or heated plasmas, taking place locally over 20 ms, which led to a new equilibrium. This new equilibrium correspond to a local increased power flux density to the limiter as confirmed by calorimetric measurements. Shot after shot, an increasing number of independent overheated zones (up to 4) were observed on the limiter ridge, the closest location to Last Closed Flux Surface (LCFS). The power extracted by the limiter then was {approximately} 1.1 MW (6.9 MW/m{sup 2} average and 15 MW/m{sup 2} maximum). Experimental data and possible mechanisms leading to a finite increased heat flux to the limiter surface are reviewed and comparisons with modelization are made.

  6. Effects of fluctuations on propagating fronts

    NASA Astrophysics Data System (ADS)

    Panja, Debabrata

    Propagating fronts are seen in varieties of nonequilibrium pattern forming systems in Physics, Chemistry and Biology. In the last two decades, many researchers have contributed to the understanding of the underlying dynamics of the propagating fronts. Of these, the deterministic and mean-field dynamics of the fronts were mostly understood in late 1980s and 1990s. On the other hand, although the earliest work on the effect of fluctuations on propagating fronts dates back to early 1980s, the subject of fluctuating fronts did not reach its adolescence until the mid 1990s. From there onwards the last few years witnessed a surge in activities in the effect of fluctuations on propagating fronts. Scores of papers have been written on this subject since then, contributing to a significant maturity of our understanding, and only recently a full picture of fluctuating fronts has started to emerge. This review is an attempt to collect all the works on fluctuating (propagating) fronts in a coherent and cogent manner in proper perspective. It is based on the idea of making our knowledge in this field available to a broader audience, and it is also expected to help to collect bits and pieces of loose thread-ends together for possible further investigation.

  7. Role of prokaryotic biomasses and activities in carbon and phosphorus cycles at a coastal, thermohaline front and in offshore waters (Gulf of Manfredonia, Southern Adriatic Sea).

    PubMed

    Monticelli, L S; Caruso, G; Decembrini, F; Caroppo, C; Fiesoletti, F

    2014-04-01

    The Western areas of the Adriatic Sea are subjected to inputs of inorganic nutrients and organic matter that can modify the trophic status of the waters and consequently, the microbiological processes involved in the carbon and phosphorus biogeochemical cycles, particularly in shallow coastal environments. To explore this topic, a survey was carried out during the spring of 2003 in a particular hydrodynamic area of the Gulf of Manfredonia, where the potential (P) and real (R) rates of four different microbial exoenzymatic activities (EEA) (α [αG] and ß glucosidases [ßG], leucine aminopeptidase [LAP], and alkaline phosphatase [AP]) as well as the P and R rates of prokaryotic heterotrophic production (PHP), AP as well as the P and R rates of PHP, primary production (PPnet), the prokaryotic and phototrophic stocks and basic hydrological parameters were examined. Three different water masses were found, with a thermohaline front (THF) being detected between the warmer and less saline coastal waters and colder and saltier offshore Adriatic waters. Under the general oligotrophic conditions of the entire Gulf, a decreasing gradient from the coastal toward the offshore areas was detected, with PHP, PPnet, stocks and EEA (αG, ßG, AP) being directly correlated with the temperature and inversely correlated with the salinity, whereas opposite relationships were observed for LAP activity. No enhancement of microbiological activities or stocks was observed at the THF. The use of P or R rates of microbiological activities, which decrease particularly for EEA, could result in discrepancies in interpreting the efficiency of several metabolic processes.

  8. Light-front view of the axial anomaly

    SciTech Connect

    Ji, Chueng-Ryong |; Rey, Soo-Jong

    1995-07-01

    Motivated by an apparent puzzle of the light-front vacua incompatible with the axial anomaly, we have considered the two-dimensional massless Schwinger model for an arbitrary interpolating angle of the quantization surface. By examining spectral deformation of the Dirac sea under an external electric field semiclassically, we have found that the axial anomaly is quantization angle independent. This indicates an intricate nontrivial vacuum structure present even in the light-front limit.

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

    NASA Astrophysics Data System (ADS)

    Penney, Camilla; Copley, Alex; Oveisi, Benham

    2016-04-01

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

  10. Active Deformation in the Zagros-Makran Transition Zone Inferred From GPS, Tectonic and Seismological Measurements

    NASA Astrophysics Data System (ADS)

    Bayer, R.; Shabanian, E.; Regard, V.; Yaminifard, F.; Vernant, P.; Nilforoushan, F.; Abbassi, M.; Chery, J.; Tatar, M.; Doerflinger, E.; Peyret, M.; Daignières, M.; Bellier, O.; Hatzfeld, D.; Mokhtari, M.

    2002-12-01

    The present-day N-S convergence between the Arabian and the Eurasian plates is accommodated in Southern Iran along the Zagros fold and thrust belt (with a shortening of ~8 mm/yr)and by the subduction of the Oman oceanic lithosphere beneath the Makran (with a rate of 18mm/yr). The Bandar Abbas-Strait of Hormuz zone is considered as a transition between the Zagros continental collision and the Makran oceanic subduction. In this area, the strain is mainly accommodated along the NNW-SSE trending reverse right lateral Minab-Zendan-Palami faults and along the N-S trending faults of Sarduiyeh, Jiroft and Sabzevaran. We used GPS network measurements (carried out in 2000 and 2002) to better understand how the deformation is distributed between between the Zagros continental collision and the Makran oceanic subduction. The analysis of the velocities (together with the measurements of the global network of Iran) leads to the following conclusions : - The rate of shortening in the Eastern Zagros is < 8mm/yr. It is < 5 mm/yr between the coast and the Main Zagros Thrust. - The horizontal residual velocities of the coastal sites in Zagros relative to Musandan are < 3mm/yr, evidencing for a small deformation in the Persian Gulf. - Across the Minab-Zendan-Palami faults system GPS measurements are consistent with a N-S trending reverse right lateral motion at rate of ~ 10 mm/yr. - West of the Lut block at the latitude of Khanuj, the N-S trending Sarduiyeh-Jiroft-Sabzevaran fault system is characterized by a 2 mm/yr right strike slip motion. Local seismicity is located at an unusual depth down to 35 km. Little is associated with the Minab-Zendan-Palami faults strike slip faults. They rather suggest that they are associated with a complex transition between the Zagros collision and the Makran subduction. Times delays also suggest a large heterogeneity in the crust across the fault system. These measurements support the model that the convergence from the collision to the subduction is

  11. The variety of subaerial active salt deformations in the Kuqa fold-thrust belt (China) constrained by InSAR

    NASA Astrophysics Data System (ADS)

    Colón, Cindy; Webb, A. Alexander G.; Lasserre, Cécile; Doin, Marie-Pierre; Renard, François; Lohman, Rowena; Li, Jianghai; Baudoin, Patrick F.

    2016-09-01

    Surface salt bodies in the western Kuqa fold-thrust belt of northwestern China allow study of subaerial salt kinematics and its possible correlations with weather variations. Ephemeral subaerial salt exposure during the evolution of a salt structure can greatly impact the subsequent development and deformation of its tectonic setting. Here, we present a quantitative time-lapse survey of surface salt deformation measured from interferometric synthetic aperture radar (InSAR) using Envisat radar imagery acquired between 2003 and 2010. Time series analysis and inspection of individual interferograms confirm that the majority of the salt bodies in western Kuqa are active, with significant InSAR observable displacements at 3 of 4 structures studied in the region. Subaerial salt motion toward and away from the satellite at rates up to 5 mm/yr with respect to local references. Rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) and temperature from a local weather station are used to test the relationship between seasonality and surface salt motion. We observe decoupling between surface salt motion and seasonality and interpret these observations to indicate that regional and local structural regimes exert primary control on surface salt displacement rates.

  12. Control and network system of force actuators for deformable mirror active optics in LAMOST

    NASA Astrophysics Data System (ADS)

    Zhang, Shengtao; Zhang, Zhenchao; Wang, You

    2007-12-01

    The reflecting Schmidt plate M A of LAMOST consists of 24 segmented hexagonal sub-mirrors. Each sub-mirror is 25mm thick and 1.1m in diagonal. There are 34 force actuators on the back of one sub-mirror which need to be controlled to offer precise load to create correct mirror deformation. This paper presents the control method and network configuration of force actuators for one sub-mirror. Master computer running Windows NT operation system and slave controllers running DOS operation system are connected together via Ethernet local area network (ELAN) by means of TCP/IP protocol. Adopting five slave controllers, 34 force actuators are combined into a distributed system. Master computer controls five slave controllers and five slave controllers operate 34 force actuators. Master computer communicates with slave controllers normally, which receives state of each force actuator from slave controllers and sends instructions to slave controllers via Ethernet LAN. Each slave controller operates 8 force actuators to offer correct load. Axial load capacity of force actuator is +/-150N (pull and push) with accuracy RMS <=0.05N. Force sensor is used as close-loop feedback apparatus to detect the micro load of the actuator.

  13. Partially segmented deformable mirror

    DOEpatents

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

    1991-05-21

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

  14. Partially segmented deformable mirror

    DOEpatents

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

    1991-01-01

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

  15. Influence of a moderate physical activity intervention on red cell deformability in patients suffering from chronic obstructive pulmonary disease (COPD).

    PubMed

    Ahmad, Basit; Ferrari, Nina; Montiel, Georgina; Bloch, Wilhelm; Raabe-Oetker, Anke; Skrobala, Nina; Brixius, Klara

    2013-07-01

    The present study investigates whether a moderate physical activity intervention may alter red cell deformability (RCD) of patients suffering from chronic obstructive pulmonary disease (COPD). Subjects (n = 10; age: 62 ± 4; body-mass index (BMI): 25.8 ± 7.5) performed a training regimen for 10 weeks. In the beginning of the study and after the training period, COPD patients underwent a WHO cycle ergometry test. Venous blood samples were taken before (T0), immediately after (T1) and 30 min after (T2) the intervention. RCD was measured with the laser-assisted optical rotational cell analyzer (LORCA). Significant improvements of the RCD were detected. The semi-maximal shear stress increased significantly. Acute exhaustion had no effect on RCD. Thus, the training period of 10 weeks influenced RCD.

  16. Sixty Years of Anisotropy of Magnetic Susceptibility in deformed sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Pares, Josep

    2015-02-01

    The use of the Anisotropy of Magnetic Susceptibility (AMS) has become a rather common practice in Earth Sciences since the pioneer note by Graham (1954). The versatility of the technique, and the rapidness in obtaining and processing AMS data largely improved in the past thirty years, and has generated a wealth of literature, notably on mudrock fabrics. The assessment of the current trends in magnetic fabric studies reveals that AMS has one of its largest potential in sedimentary rocks from structural settings where the ductile component of deformation is cryptic or hindered by the brittle component. Abundant evidence provided by AMS data reveal that deformation extents beyond the deformation or cleavage front in contractional settings, including fold-and-thrust belts and active accretionary prisms, configuring magnetic fabrics as a standard method for fabric quantification in deformed sedimentary rocks.

  17. Front Range Branch Officers

    NASA Astrophysics Data System (ADS)

    The Front Range Branch of AGU has installed officers for 1990: Ray Noble, National Center for Atmospheric Research, chair; Sherry Oaks, U.S. Geological Survey, chair-elect; Howard Garcia, NOAA, treasurer; Catharine Skokan, Colorado School of Mines, secretary. JoAnn Joselyn of NOAA is past chair. Members at large are Wallace Campbell, NOAA; William Neff, USGS; and Stephen Schneider, NCAR.

  18. Nanoparticle Oscillations and Fronts

    SciTech Connect

    Lagzi, Istvan; Kowalczyk, Bartlomiej; Wang, Dawei; Grzybowski, Bartosz A.

    2010-09-30

    Chemical oscillations can be coupled to the dynamic self-assembly of nanoparticles. Periodic pH changes translate into protonation and deprotonation of the ligands that stabilize the nanoparticles, thus altering repulsive and attractive interparticle forces. In a continuous stirred-tank reactor, rhythmic aggregation and dispersion is observed; in spatially distributed media, propagation of particle aggregation fronts is seen.

  19. INTEGRATION OF SHORT-TERM CO-SEISMIC DEFORMATION (InSAR) IN THE GEOMORPHIC DEVELOPMENT OF AN ACTIVELY UPLIFTING FOOTWALL, L’AQUILA EARTHQUAKE (06 APRIL, 2009), ITALY

    NASA Astrophysics Data System (ADS)

    Berti, C.; Pazzaglia, F. J.; Ramage, J. M.; Miccadei, E.; Piacentini, T.

    2009-12-01

    Central Italy is a well know region of frequent seismic activity focused along the topographic axis of the Apennines, with several, damaging > M. 5 events in the past decade. Conversely, the integrated effect of these earthquakes in shaping the long term development of the landscape is a poorly understood, but potentially powerful process in describing the region’s paleoseismicity and steadiness of hazardous earthquakes. The recent M. 6.3 L’Aquila earthquake of 06 April, 2009 ruptured a fault in a region of well-known geologic, geomorphic, and geodetic constraining data including hanging wall continental basin Quaternary deposits, footwall stream networks with distinct knickpoints, a dense GPS network, and InSAR interferometry. Collectively, the geodetic data describe the short-term, co- and immediately post-seismic behavior of the earthquake, whereas the geologic and geomorphic data record how discrete rupture events are encoded in the landscape and reflected in processes actively shaping the topography. Envisat and ALOS derived interferograms generated using ROI PAC show close spatial overlap of the InSAR-determined rupture and the Paganica fault, separating a deeply incised, uplifted carbonate footwall block and an actively subsiding Quaternary continental basin. Deposition in the continental basin has been unsteady and is commonly attributed to climate-modulated sediment flux from the uplifted footwall. We note however, that the longitudinal profiles of streams in the footwall are marked by distinct knickpoints that do not correspond to known or obvious lithologic or structural controls. Rather, the knickpoints are located a linear distance from the Paganica fault and at a topographic elevation consistent with detachment-limited stream-power erosional retreat processes instigated by instantaneous base level fall at the mountain front. Furthermore, the magnitude of river incision and elevation of the knickpoints scales with the co-seismic deformation pattern

  20. Slip-rate Estimation of Active Fault by Luminescence Dating on Deformed River Terraces at Tsaotun, Central Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Chen, W.; Lee, C.

    2003-12-01

    This study carried out luminescence ages of the deformed terraces located at Tsaotun in central Taiwan. These terraces are considered as a result of crustal deformation caused by recent activity of the Chelungpu fault, 1999 surface rupture. Since this active fault runs through urban area, it is urgently needed to figure out its neotectonic behavior, including slip-rate and recurrence interval. Based on new ages, we also discuss the terrace correlation and its related structures. The study terraces are all strath terraces with only a few meters of veneered fluvial deposits on top. Due to the strong stream-power, nearly all the outcrops are dominated by fluvial cobbles, which is worst condition to preserve the syndepositional carbonaceous materials. Alternatively, optical stimulated luminescence (OSL) dating uses sandy quartz as the material and even has longer dating upper limit (up to several hundreds of years). Fortunately, sandy layer are found intercalated within the fluvial cobbles in studying terraces. We adopted the Single-Aliquot Regenerative (SAR) dose protocol on large aliquots of 90-150μ m quartz, which were cleaned using HCL, H2O2 and HF in the usual way. In case of incomplete bleaching during quick deposition, the OSL/TL ratio was adopted to approach the true De. Dosimetry is derived by ICP-MS and XRF analyses. For ascertainment of the initial bleaching of fluvial sediment, the modern samples collected in river bed of Wuhsi were also measured. Based on the results of modern samples, we believe that the residuals are inevitable in younger sediments, especially along the upper stream. On the contrary, the samples older than 10 kyr are little influenced due to the larger age error than the younger ones. The OSL age of the terrace samples in the hanging wall is dated ca. 13 kyr, which has been corrected for poorly-bleaching problem. Comparing to the ages collected down hole in the footwalls, we found out vertical displacements of ca. 67 and 37 m, has been

  1. Experimental and numerical investigation on the motorcycle front frame flexibility and its effect on stability

    NASA Astrophysics Data System (ADS)

    Cossalter, V.; Doria, A.; Massaro, M.; Taraborrelli, L.

    2015-08-01

    It is well known that front fork flexibility may have a significant effect on motorcycle stability. This work addresses the problem of developing lumped element models of the front fork from experimental results. The front forks of an enduro motorcycle and of a super sport motorcycle are characterized performing static, dynamic and modal tests by means of specific testing equipment. The concept of wheel twisting axis is proposed to characterize static and dynamic deformability of the front fork. Modal analysis results show the presence of two important modes of vibration of the front assembly in the low frequency range: the lateral mode and the longitudinal mode. Different lumped models are discussed and a new model that takes into account information obtained from static and dynamic tests is proposed. Simulations are carried out by means of a multibody code and show the effect of the front assembly deformability on the weave and wobble vibration modes.

  2. 9. DETAIL OF INTERIOR OF FRONT PORCH SHOWING FRONT ENTRY ...

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

    9. DETAIL OF INTERIOR OF FRONT PORCH SHOWING FRONT ENTRY (LEFT) AND BLANK WALL (CENTER) CORRESPONDING TO LOCATION OF INTERIOR VAULTS. VIEW TO SOUTHEAST. - Boise Project, Boise Project Office, 214 Broadway, Boise, Ada County, ID

  3. 35. EAST FRONT OF POWERHOUSE AND CAR BARN: East front ...

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

    35. EAST FRONT OF POWERHOUSE AND CAR BARN: East front of powerhouse and car barn. 'Annex' is right end of building. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

  4. 4. BARRACKS, WITH PARKING LOT IN FRONT, FRONT AND RIGHT ...

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

    4. BARRACKS, WITH PARKING LOT IN FRONT, FRONT AND RIGHT SIDES, LOOKING SOUTH. - NIKE Missile Base SL-40, Barracks No. 2, North end of base, southeast of Barracks No. 1 & northeast of Mess Hall, Hecker, Monroe County, IL

  5. 1. BARRACKS, WITH PARKING LOT IN FRONT, FRONT, LOOKING SOUTHWEST. ...

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

    1. BARRACKS, WITH PARKING LOT IN FRONT, FRONT, LOOKING SOUTHWEST. - NIKE Missile Base SL-40, Barracks No. 2, North end of base, southeast of Barracks No. 1 & northeast of Mess Hall, Hecker, Monroe County, IL

  6. 3. VIEW NORTH, SOUTHWEST FRONT, SOUTHEAST SIDE Front and side ...

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

    3. VIEW NORTH, SOUTHWEST FRONT, SOUTHEAST SIDE Front and side elevation. Note gasoline sign post added. Flush store window not altered, 1900 clapboard siding and panelling remaining. - 510 Central Avenue (Commercial Building), Ridgely, Caroline County, MD

  7. Spinal deformity.

    PubMed

    Bunnell, W P

    1986-12-01

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

  8. Analysis of slip activity and heterogeneous deformation in tension and tension-creep of Ti-5Al-2.5Sn (wt %) using in-situ SEM experiments

    NASA Astrophysics Data System (ADS)

    Li, H.; Boehlert, C. J.; Bieler, T. R.; Crimp, M. A.

    2012-08-01

    The deformation behavior of a Ti-5Al-2.5Sn (wt %) near-α alloy was investigated during in-situ deformation inside a scanning electron microscope. Tensile experiments were performed at 296 K and 728 K (≈0.4 T m), while tensile-creep experiments were performed at 728 K and 763 K. Active deformation systems were identified using electron backscattered diffraction-based slip trace analysis. Both basal and prismatic slip systems were active during the tensile experiments. Basal slip was observed for grains clustered around high Schmid factor orientations, while prismatic slip exhibited less dependence on the crystallographic orientation. The tension-creep experiments revealed less slip but more development of grain boundary ledges than in the higher strain rate tensile experiments. Some of the grain boundary ledges evolved into grain boundary cracks, and grain boundaries oriented nearly perpendicular to the tensile axis formed ledges earlier in the deformation process. Grain boundaries with high misorientations also tended to form ledges earlier than those with lower misorientations. Most of the grain boundary cracks formed in association with grains displaying hard orientations, where the c-axis was nearly perpendicular to the tensile direction. For the tension-creep experiments, pronounced basal slip was observed in the lower-stress creep regime and the activity of prismatic slip increased with increasing creep stress and temperature.

  9. Quaternary hinterland evolution of the active Banda Arc: Surface uplift and neotectonic deformation recorded by coral terraces at Kisar, Indonesia

    NASA Astrophysics Data System (ADS)

    Major, Jonathan; Harris, Ron; Chiang, Hong-Wei; Cox, Nicole; Shen, Chuan-Chou; Nelson, Stephen T.; Prasetyadi, Carolus; Rianto, Arif

    2013-09-01

    Coral terrace surveys and U-series ages of coral yield a surface uplift rate of ∼0.5 m/ka for Kisar Island, which is an emergent island in the hinterland of the active Banda arc-continent collision. Based on this rate, Kisar first emerged from the ocean as recently as ∼450 ka. These uplifted terraces are gently warped in a pattern of east-west striking folds. These folds are strike parallel to more developed thrust-related folds of similar wavelength imaged by a seismic reflection profile just offshore. This deformation shows that the emergence of Kisar is influenced by forearc closure along the south-dipping Kisar Thrust. However, the pinnacle shape of Kisar and the protrusion of its metamorphic rocks through the forearc basin sediments also suggest a component of extrusion along shear zones or active doming. Coral encrusts the island coast in many locations over 100 m above sea level. Terrace morphology and coral ages are best explained by recognizing major surfaces as mostly growth terraces and minor terraces as mostly erosional into older terraces. All reliable and referable coral U-series ages determined by MC-ICP-MS correlate with marine isotope stage (MIS) 5e (118-128 ka). The only unaltered coral samples are found below 6 m elevation; however an unaltered Tridacna (giant clam) shell in growth position at 95 m elevation yields a U-series age of 195 ± 31 ka, which corresponds to MIS 7. This age agrees with the best-fit uplift model for the island. Loose deposits of unaltered coral fragments found at elevations between 8 and 20 m yield U-series ages of <100 years and may represent paleotsunami deposits from previously undocumented tectonic activity in the region.

  10. Thermomechanics of shallow magma chamber pressurization: Implications for the assessment of ground deformation data at active volcanoes

    NASA Astrophysics Data System (ADS)

    Gregg, P. M.; de Silva, S. L.; Grosfils, E. B.

    2013-12-01

    In this study, we utilize thermomechanical models to investigate how magma chambers overpressurize as the result of either magmatic recharge or volatile exsolution. By implementing an adaptive reservoir boundary condition we are able to track how overpressure dissipates as the magma chamber expands to accommodate internal volume changes. We find that the size of the reservoir greatly impacts the resultant magma chamber overpressure. In particular, overpressure estimates for small to moderate-sized reservoirs (1-10 km3) are up to 70% lower than previous analytical predictions. We apply our models to Santorini volcano in Greece where recent seismic activity and ground deformation observations suggested the potential for eruption. The incorporation of an adaptive boundary condition reproduces Mogi flux estimates and suggests that the magma reservoir present at Santorini may be quite large. Furthermore, model results suggest that if the magma chamber is >100 km3, overpressures generated due to the high magma flux may not exceed the strength of the host rock, thus requiring an additional triggering mechanism for eruption. Although the adaptive boundary condition approach does not calculate the internal evolution of the magma reservoir, it represents a fundamental step forward from elastic Mogi models and fixed boundary solutions on which future investigations of the evolution of the magma can be built.

  11. Remote ischemia preconditioning increases red blood cell deformability through red blood cell-nitric oxide synthase activation.

    PubMed

    Grau, Marijke; Kollikowski, Alexander; Bloch, Wilhelm

    2016-09-12

    Remote ischemia preconditioning (rIPC), short cycles of ischemia (I) and reperfusion (R) of a region remote from the heart, protects against myocardial I/R injury. This effect is triggered by endothelial derived nitric oxide (NO) production. Red blood cells (RBC) are also capable of NO production and it is hypothesized that the beneficial effect of rIPC in terms of cardioprotection is strengthened by increased RBC dependent NO production and improved RBC function after rIPC maneuver. For this purpose, twenty male participants were subjected to four cycles of no-flow ischemia with subsequent reactive hyperemia within the forearm. Blood sampling and measurement of blood pressures and heart rate were carried out pre intervention, after each cycle and 15 min post intervention at both the non-treated and treated arm. These are the first results that show improved RBC deformability in the treated arm after rIPC cycles 1- 4 caused by significantly increased RBC-NO synthase activation. This in turn was associated to increased NO production in both arms after rIPC cycles 3 + 4. Also, systolic and diastolic blood pressures were decreased after rIPC. The findings lead to the conclusion that the cardioprotective effects associated with rIPC include improvement of the RBC-NOS/NO signaling in RBC.

  12. Active tectonic deformation along rejuvenated faults in tropical Borneo: Inferences obtained from tectono-geomorphic evaluation

    NASA Astrophysics Data System (ADS)

    Mathew, Manoj Joseph; Menier, David; Siddiqui, Numair; Kumar, Shashi Gaurav; Authemayou, Christine

    2016-08-01

    active folding of the Rajang Group fold-thrust belt to present and these events reactivated old major faults and minor related dislocations. From geomorphic analysis associated with sedimentary record, we posit that the terrain could have undergone high uplift rates since 5 Ma or multi-phased uplift with periodic intermittent pulses of high and low uplift rates.

  13. ARIEL front end

    NASA Astrophysics Data System (ADS)

    Marchetto, M.; Baartman, R. A.; Laxdal, R. E.

    2014-01-01

    The ARIEL project at TRIUMF will greatly expand the variety and availability of radioactive ion beams (RIBs) (Laxdal, Nucl Inst Methods Phys Res B 204:400-409, 2003). The ARIEL front end connects the two ARIEL target stations to the existing ISAC facility to expand delivery to two and eventually three simultaneous RIB beams with up to two simultaneous accelerated beams (Laxdal et al. 2008). The low-energy beam transport lines and mass separators are designed for maximum flexibility to allow a variety of operational modes in order to optimize the radioactive ion beam delivery. A new accelerator path is conceived for high mass delivery from an EBIS charge state breeder. The front-end design utilizes the experience gained in 15 years of ISAC beam delivery.

  14. Investigation of remnant versus active deformation in the lithosphere beneath south Africa from shear-wave splitting

    NASA Astrophysics Data System (ADS)

    emuh, M.; Nyblade, A.; Weeraratne, D. S.

    2012-12-01

    South Africa is comprised of several continental blocks formed during previous collisional events, which date back 2-3 Ga. The three main blocks known as the Pietersburg, Kimberley, and Witwatersrand blocks are delineated by ancient subduction boundaries such as the Colesberg lineament. We consider whether these continental blocks retain remnant deformation at lithospheric depths from ancient collisional events or are governed by stresses due to current plate motion and mantle flow. We use shear-wave splitting methods to study seismic anisotropy from teleseismic phases. Splitting measurements are obtained by minimizing the smallest eigenvalue, maximizing the ratio of the smallest and largest eigenvalues, and rotation correlation, using the graphical user interface Splitlab. We only consider results that show consistency between multiple methods. The seismic data was collected from a new deployment of AfricaArray stations in south Africa and consists of 28 earthquake events. Earthquakes used in this study have a good azimuthal distribution with the poorest coverage only in the NW and S directions. Stations located within the Witwatersrand block display consistent results with a NE fast direction and an average delay time of 1.01 +/- 0.4 s. One station west of the Colesberg lineament in the Kimberley block yields a NW-SE fast direction for all measurements and is nearly perpendicular to results from stations east of this boundary. Stations south of Kaapvaal craton show dependence on the back azimuth of earthquake arrivals. Paths which travel through the Namaqua-Natal fold belt all produce N-S fast directions with average delay times of 0.9 s. Raypaths that travel through the southern Saldania fold belt produce NW-SE fast directions. We suggest that seismic anisotropy in this region represents active deformation in the Witwatersrand block dictated by current tectonic stresses and absolute plate motion. Remnant fabric from ancient tectonic collisional events may still

  15. Active Deformation in the Greater Himalayan Zone in Western Nepal from Inversion of New (U-Th)/He Cooling Ages

    NASA Astrophysics Data System (ADS)

    Harvey, J. E.; Burbank, D.

    2015-12-01

    Much of the central Himalaya features an abrupt rise in mean elevation from ~1.5 km in the Lesser Himalaya to ~4-5 km Greater Himalaya and Tibetan Plateau. This physiographic transition is known as PT2, and is often interpreted as the surface expression of transport over a ramp in the Main Himalayan Thrust (MHT). In western Nepal, however, the same rise in elevation occurs over two distinct topographic steps (PT2-N and PT2-S). In previous work, Harvey et al. (2015) argue that this anomalous topography is the result of recent southward-migration of mid-crustal deformation along the MHT. Due to the seismogenic potential of the MHT it is important to constrain its geometry in the western Nepal seismic gap, which has not had a large earthquake in over 600 years. To test the above hypothesis, we perform [U-Th]/He dating on 39 apatite and 47 zircon samples collected along seven relief transects throughout western Nepal. We constrain exhumation histories by inverting these new cooling ages with the 3-D thermo-kinematic model Pecube. Five transects collected from the Greater Himalaya north of PT2-N are best fit by relatively rapid exhumation rates (~1-2 km/Myr) since ~4 Ma. The other two, collected from farther south near PT2-S, require rapid (~1-2 km/Myr) exhumation until around 8-11 Ma, followed by much slower (~0.1-0.2 km/Myr) exhumation until at least the late Pliocene. Assuming that exhumation rates reflect uplift rates, the rapid Plio-Pleistocene exhumation in the Greater Himalaya north of PT2-N suggest that this physiographic transition is similar to that at the foot of the Greater Himalaya in central Nepal. It follows that active deformation is occurring along a NW-trend as much as 100 km farther north than would be expected if simply projecting PT2 across western Nepal. This finding is consistent with transport over a more northerly MHT ramp or perhaps oblique slip along the recently identified, surface-breaking WNFZ. Although the geomorphology and microseismicity

  16. Theory of pinned fronts

    NASA Astrophysics Data System (ADS)

    Weissmann, Haim; Shnerb, Nadav M.; Kessler, David A.

    2016-01-01

    The properties of a front between two different phases in the presence of a smoothly inhomogeneous external field that takes its critical value at the crossing point is analyzed. Two generic scenarios are studied. In the first, the system admits a bistable solution and the external field governs the rate in which one phase invades the other. The second mechanism corresponds to a continuous transition that, in the case of reactive systems, takes the form of a transcritical bifurcation at the crossing point. We solve for the front shape and for the response of competitive fronts to external noise, showing that static properties and also some of the dynamical features cannot discriminate between the two scenarios. A reliable indicator turns out to be the fluctuation statistics. These take a Gaussian form in the bifurcation case and a double-peaked shape in a bistable system. Our results are discussed in the context of biological processes, such as species and communities dynamics in the presence of a resource gradient.

  17. Radiative thermal conduction fronts

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

  18. On the use of the activation energy concept to investigate analyte and network deformations in entangled polymer solution capillary electrophoresis of synthetic polyelectrolytes.

    PubMed

    Cottet, H; Gareil, P

    2001-01-01

    The activation energy associated with the electrophoretic migration of an analyte under given electrolyte conditions can be accessed through the determination of the analyte electrophoretic mobility at various temperatures. In the case of the electrophoretic separation of polyelectrolytes in the presence of an entangled polymer network, activation energy can be regarded as the energy needed by the analyte to overcome the obstacles created by the separating network. Any deformation undergone by the analyte or the network is expected to induce a decrease in the activation energy. In this work, the electrophoretic mobilities of poly(styrenesulfonates) (PSSs) of various molecular weights (Mr 16 x 10(3) to 990 x 10(3)) were determined in entangled polyethylene oxide (PEO) solutions as a function of temperature (in the 17-60 degrees C range) and the PSS activation energies were calculated. The influences of the PSS molecular weight, blob sizes zetab of the separating network (related to the PEO concentration), ionic strength of the electrolyte and electric field strength (75-600 V/cm) were investigated. The results were interpreted in terms of analyte and network deformations and were confronted with those previously obtained for DNA migration in polymer solutions and chemical gels. For a radius of gyration Rgactivation energy increases with the PSS molecular mass, while the reverse is true for Rg>zetab, suggesting PSS and network deformations in the latter case. Increasing ionic strength resulted in an increase in the PSS activation energy, because of the decrease of their radii of gyration, which makes them less deformable. Finally, the activation energies of all the PSSs are a decreasing function of field strength and at high field strength tend to reach a constant value close to that for a small molecule.

  19. Transcriptional responses, metabolic activity and mouthpart deformities in natural populations of Chironomus riparius larvae exposed to environmental pollutants.

    PubMed

    Planelló, Rosario; Servia, María J; Gómez-Sande, Pablo; Herrero, Óscar; Cobo, Fernando; Morcillo, Gloria

    2015-04-01

    Biomarkers are an important tool in laboratory assays that link exposure or effect of specific toxicants to key molecular and cellular events, but they have not been widely used in invertebrate populations exposed to complex mixtures of environmental contaminants in their natural habitats. The present study focused on a battery of biomarkers and their comparative analysis in natural populations of the benthic larvae of Chironomus riparius (Diptera), sampled in three differentially polluted rivers (the Con, Sar, and Louro in Galicia, Spain). In our study, some parameters were identified, such as hsp70 gene activity, GST enzymatic activity, total glycogen content and mouthpart deformities, which showed significant differences among populations from the three rivers that differed in the levels and types of sedimentary contaminants analyzed (metals, organic-chlorine pesticides, alkylphenols, pharmaceutical, and personal care products). In contrast to these sensitive biomarkers, other parameters showed no significant differences (hsc70 gene, EcR gene, P450 gene, RNA:DNA ratio, total protein content), and were stable even when comparing field and nonexposed laboratory populations. The hsp70 gene seems to be particularly sensitive to conditions of pollutant exposure, while its constitutive counterpart hsc70 showed invariable expression, suggesting that the hsc70/hsp70 ratio may be a potential indicator of polluted environments. Although further studies are required to understand the correlation between molecular responses and the ecological effects of pollutants on natural populations, the results provide new data about the biological responses to multiple-stressor environments. This field study adds new molecular endpoints, including gene expression, as suitable tools that, complementing other ecotoxicological parameters, may help to improve the methodologies of freshwater monitoring under the increasing burden of xenobiotics. PMID:23893657

  20. Transcriptional responses, metabolic activity and mouthpart deformities in natural populations of Chironomus riparius larvae exposed to environmental pollutants.

    PubMed

    Planelló, Rosario; Servia, María J; Gómez-Sande, Pablo; Herrero, Óscar; Cobo, Fernando; Morcillo, Gloria

    2015-04-01

    Biomarkers are an important tool in laboratory assays that link exposure or effect of specific toxicants to key molecular and cellular events, but they have not been widely used in invertebrate populations exposed to complex mixtures of environmental contaminants in their natural habitats. The present study focused on a battery of biomarkers and their comparative analysis in natural populations of the benthic larvae of Chironomus riparius (Diptera), sampled in three differentially polluted rivers (the Con, Sar, and Louro in Galicia, Spain). In our study, some parameters were identified, such as hsp70 gene activity, GST enzymatic activity, total glycogen content and mouthpart deformities, which showed significant differences among populations from the three rivers that differed in the levels and types of sedimentary contaminants analyzed (metals, organic-chlorine pesticides, alkylphenols, pharmaceutical, and personal care products). In contrast to these sensitive biomarkers, other parameters showed no significant differences (hsc70 gene, EcR gene, P450 gene, RNA:DNA ratio, total protein content), and were stable even when comparing field and nonexposed laboratory populations. The hsp70 gene seems to be particularly sensitive to conditions of pollutant exposure, while its constitutive counterpart hsc70 showed invariable expression, suggesting that the hsc70/hsp70 ratio may be a potential indicator of polluted environments. Although further studies are required to understand the correlation between molecular responses and the ecological effects of pollutants on natural populations, the results provide new data about the biological responses to multiple-stressor environments. This field study adds new molecular endpoints, including gene expression, as suitable tools that, complementing other ecotoxicological parameters, may help to improve the methodologies of freshwater monitoring under the increasing burden of xenobiotics.

  1. Dynamic performance of MEMS deformable mirrors for use in an active/adaptive two-photon microscope

    NASA Astrophysics Data System (ADS)

    Zhang, Christian C.; Foster, Warren B.; Downey, Ryan D.; Arrasmith, Christopher L.; Dickensheets, David L.

    2016-03-01

    Active optics can facilitate two-photon microscopic imaging deep in tissue. We are investigating fast focus control mirrors used in concert with an aberration correction mirror to control the axial position of focus and system aberrations dynamically during scanning. With an adaptive training step, sample-induced aberrations may be compensated as well. If sufficiently fast and precise, active optics may be able to compensate under-corrected imaging optics as well as sample aberrations to maintain diffraction-limited performance throughout the field of view. Toward this end we have measured a Boston Micromachines Corporation Multi-DM 140 element deformable mirror, and a Revibro Optics electrostatic 4-zone focus control mirror to characterize dynamic performance. Tests for the Multi-DM included both step response and sinusoidal frequency sweeps of specific Zernike modes. For the step response we measured 10%-90% rise times for the target Zernike amplitude, and wavefront rms error settling times. Frequency sweeps identified the 3dB bandwidth of the mirror when attempting to follow a sinusoidal amplitude trajectory for a specific Zernike mode. For five tested Zernike modes (defocus, spherical aberration, coma, astigmatism and trefoil) we find error settling times for mode amplitudes up to 400nm to be less than 52 us, and 3 dB frequencies range from 6.5 kHz to 10 kHz. The Revibro Optics mirror was tested for step response only, with error settling time of 80 μs for a large 3 um defocus step, and settling time of only 18 μs for a 400nm spherical aberration step. These response speeds are sufficient for intra-scan correction at scan rates typical of two-photon microscopy.

  2. Faults Activities And Crustal Deformation Along The Arc-Continent Collision Boundary, Eastern Taiwan - Observed From Persistent Scatterer SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Yen, Jiun-Yee; Chang, Chung-Pai; Hooper, Andrew; Chang, Yo-Ho; Liang, Wen-Tzong; Chang, Tsui-Yu

    2010-05-01

    Located in the southeastern periphery of the Eurasian plate, eastern Taiwan marks the collional boundary between the Eurasian plate and the Philippine Sea plate. These two plates converge at about 8 cm/yr near Taiwan and nearly half of the shortening is consumed in eastern Taiwan. There have been many studies in this area about the dynamics of the plate convergence, however, most of the geodetic studies focused on small area (strainmeter), with very few data points (GPS), or only gather data along a specific profile (leveling). We applied the Persistent Scatterer SAR Interferometry in the Longitudinal Valley of eastern Taiwan to observe temporally-variable processes using both ERS and Envisat data. At the same time, leveling and GPS data were measured for the auxiliary tool to verify the deformation rate in this area. Our result indicated that although the area is under active collision, faults do not move in the same fashion along the boundary. In the very northern part of the collided arc, small subsidence has been detected, while in the north-central part very few activity is observed. In the central and southern part of the collisional boundary, patches of faults are moving as rapidly as 15 mm/yr along radar line-of-sight. In addition. between late 2004 and middle 2005 there had been an earthquake swarm consists of shallow earthquakes, which coincided with PSI observation of a large vertical displacement. The comparison between our leveling data and PS results indicated PSI is a reliable tool even in the highly vegetated area in eastern Taiwan.

  3. Morphological studies of front limb deformities in lambs.

    PubMed

    Uhthoff, H K; Liskova-Kiar, M; Hidiroglou, M

    1980-05-01

    Long bones of 16 3- to 6-month-old lambs with bowed forelimbs underwent radiologic, microradiographic and histologic examinations. The distal ends of the radii showed a combination of valgus, flexion and internal rotation. There were thin cortical bone and large marrow cavity adjacent to the growth plate in the radii and metacarpi. Histological studies showed increased numbers of osteoclasts adjacent to the zone of calcified cartilage of the growth plate. The trabeculae of primary and secondary spongiosa were fewer and thinner than those of controls. The length of secondary spongiosa were greatly reduced and the lateral compaction of the metaphysis was defective. The growth plate was normal. The predominant finding was osteoporosis resulting from increased osteoclastic resorption of bone trabeculae.

  4. THERMAL FRONTS IN SOLAR FLARES

    SciTech Connect

    Karlický, Marian

    2015-12-01

    We studied the formation of a thermal front during the expansion of hot plasma into colder plasma. We used a three-dimensional electromagnetic particle-in-cell model that includes inductive effects. In early phases, in the area of the expanding hot plasma, we found several thermal fronts, which are defined as a sudden decrease of the local electron kinetic energy. The fronts formed a cascade. Thermal fronts with higher temperature contrast were located near plasma density depressions, generated during the hot plasma expansion. The formation of the main thermal front was associated with the return-current process induced by hot electron expansion and electrons backscattered at the front. A part of the hot plasma was trapped by the thermal front while another part, mainly with the most energetic electrons, escaped and generated Langmuir and electromagnetic waves in front of the thermal front, as shown by the dispersion diagrams. Considering all of these processes and those described in the literature, we show that anomalous electric resistivity is produced at the location of the thermal front. Thus, the thermal front can contribute to energy dissipation in the current-carrying loops of solar flares. We estimated the values of such anomalous resistivity in the solar atmosphere together with collisional resistivity and electric fields. We propose that the slowly drifting reverse drift bursts, observed at the beginning of some solar flares, could be signatures of the thermal front.

  5. Thermal Fronts in Solar Flares

    NASA Astrophysics Data System (ADS)

    Karlický, Marian

    2015-12-01

    We studied the formation of a thermal front during the expansion of hot plasma into colder plasma. We used a three-dimensional electromagnetic particle-in-cell model that includes inductive effects. In early phases, in the area of the expanding hot plasma, we found several thermal fronts, which are defined as a sudden decrease of the local electron kinetic energy. The fronts formed a cascade. Thermal fronts with higher temperature contrast were located near plasma density depressions, generated during the hot plasma expansion. The formation of the main thermal front was associated with the return-current process induced by hot electron expansion and electrons backscattered at the front. A part of the hot plasma was trapped by the thermal front while another part, mainly with the most energetic electrons, escaped and generated Langmuir and electromagnetic waves in front of the thermal front, as shown by the dispersion diagrams. Considering all of these processes and those described in the literature, we show that anomalous electric resistivity is produced at the location of the thermal front. Thus, the thermal front can contribute to energy dissipation in the current-carrying loops of solar flares. We estimated the values of such anomalous resistivity in the solar atmosphere together with collisional resistivity and electric fields. We propose that the slowly drifting reverse drift bursts, observed at the beginning of some solar flares, could be signatures of the thermal front.

  6. Levelling profiles and a GPS network to monitor the active folding and faulting deformation in the Campo de Dalias (Betic Cordillera, southeastern Spain).

    PubMed

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Gil, Antonio José; Borque, María Jesús; de Lacy, María Clara; Pedrera, Antonio; López-Garrido, Angel Carlos; Alfaro, Pedro; García-Tortosa, Francisco; Ramos, Maria Isabel; Rodríguez-Caderot, Gracia; Rodríguez-Fernández, José; Ruiz-Constán, Ana; de Galdeano-Equiza, Carlos Sanz

    2010-01-01

    The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. PMID:22319309

  7. Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)

    PubMed Central

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Gil, Antonio José; Borque, María Jesús; de Lacy, María Clara; Pedrera, Antonio; López-Garrido, Angel Carlos; Alfaro, Pedro; García-Tortosa, Francisco; Ramos, Maria Isabel; Rodríguez-Caderot, Gracia; Rodríguez-Fernández, José; Ruiz-Constán, Ana; de Galdeano-Equiza, Carlos Sanz

    2010-01-01

    The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. PMID:22319309

  8. Coseismic Faulting and Folding in an Active Thrust Sheet over Multiple Rupture Cycles Resolved by Integrating Surface and Subsurface Records of Earthquake Deformation

    NASA Astrophysics Data System (ADS)

    Stockmeyer, J. M.; Shaw, J. H.; Brown, N.; Rhodes, E. J.; Wang, M.; Lavin, L. C.; Guan, S.

    2015-12-01

    Many recent thrust fault earthquakes have involved coseismic surface faulting and folding, revealing the complex nature of surface deformation in active thrust sheets. In this study, we characterize deformation along the active Southern Junggar Thrust (SJT) in the Junggar basin, NW China - which sourced the 1906 M8 Manas earthquake - to gain insight into how fault slip at depth is partitioned between faulting and folding strains at Earth's surface by integrating deformed terrace records, subsurface geophysical data, and luminescence geochronology. Using a 1-m digital elevation model and field surveys, we have mapped the precise geometries of fluvial terraces across the entire Tugulu anticline, which lies in the hanging wall of the SJT. These profiles reveal progressive uplift of several terraces along prominent fault scarps where the SJT is surface-emergent. Similarly aged terraces are folded in the backlimb of the Tugulu fold, providing a sequential record of surface folding. These folded terraces are progressively rotated such that the oldest terraces are dipping much steeper than younger terraces within the same fold limb. Using 2- and 3-D seismic reflection data, we integrate subsurface deformation constraints with records of surface strain. Structural interpretations of these seismic data define the geometry of the SJT and reveal that folding is localized across synclinal bends along the SJT. We evaluate a range of distinct fault-related fold models (e.g. fault-bend folding, shear fault-bend folding) to assess which structural style best describes the geometries of the subsurface and surface fold patterns. By doing so, we have the opportunity to directly relate surface fault slip measures from terrace folding and uplift to total fault slip at depth. This integration of surface and subsurface deformation - combined with constraints on terrace ages from post-IR IRSL geochronology - allows us to characterize how fault slip and seismic moment are partitioned

  9. Gravity changes and deformation at Kīlauea Volcano, Hawaii, associated with summit eruptive activity, 2009-2012

    USGS Publications Warehouse

    Bagnardi, Marco; Poland, Michael P.; Carbone, Daniele; Baker, Scott; Battaglia, Maurizio; Amelung, Falk

    2014-01-01

    Analysis of microgravity and surface displacement data collected at the summit of Kīlauea Volcano, Hawaii (USA), between December 2009 and November 2012 suggests a net mass accumulation at ~1.5 km depth beneath the northeast margin of Halema‘uma‘u Crater, within Kīlauea Caldera. Although residual gravity increases and decreases are accompanied by periods of uplift and subsidence of the surface, respectively, the volume change inferred from the modeling of interferometric synthetic aperture radar deformation data can account for only a small portion (as low as 8%) of the mass addition responsible for the gravity increase. We propose that since the opening of a new eruptive vent at the summit of Kīlauea in 2008, magma rising to the surface of the lava lake outgasses, becomes denser, and sinks to deeper levels, replacing less dense gas-rich magma stored in the Halema‘uma‘u magma reservoir. In fact, a relatively small density increase (<200 kg m−3) of a portion of the reservoir can produce the positive residual gravity change measured during the period with the largest mass increase, between March 2011 and November 2012. Other mechanisms may also play a role in the gravity increase without producing significant uplift of the surface, including compressibility of magma, formation of olivine cumulates, and filling of void space by magma. The rate of gravity increase, higher than during previous decades, varies through time and seems to be directly correlated with the volcanic activity occurring at both the summit and the east rift zone of the volcano.

  10. Left-lateral active deformation along the Mosha-North Tehran fault system (Iran): Morphotectonics and paleoseismological investigations

    NASA Astrophysics Data System (ADS)

    Solaymani Azad, Shahryar; Ritz, Jean-François; Abbassi, Mohammad Reza

    2011-01-01

    The Mosha and North Tehran faults correspond to the nearest seismic sources for the northern part of the Tehran megacity. The present-day structural relationships and the kinematics of these two faults, especially at their junction in Lavasanat region, is still a matter of debate. In this paper, we present the results of a morphotectonic analysis (aerial photos and field investigations) within the central part of the Mosha and eastern part of the North Tehran faults between the Mosha valley and Tehran City. Our investigations show that, generally, the traces of activity do not follow the older traces corresponding to previous long-term dip-slip thrusting movements. The recent faulting mainly occurs on new traces trending E-W to ENE-WSW affecting Quaternary features (streams, ridges, risers, and young glacial markers) and cutting straight through the topography. Often defining en-echelon patterns (right- and left-stepping), these new traces correspond to steep faults with either north- or south-dipping directions, along which clear evidences for left-lateral strike-slip motion are found. At their junction zone, the two sinistral faults display a left-stepping en-echelon pattern defining a positive flower structure system clearly visible near Ira village. Further west, the left-lateral strike-slip motion is transferred along the ENE-WSW trending Niavaran fault and other faults. The cumulative offsets associated with this left-lateral deformation is small compared with the topography associated with the previous Late Tertiary thrusting motion, showing that it corresponds to a recent change of kinematics.

  11. Ongoing Active Deformation Processes at Fernandina Volcano (Galapagos) Detected via Multi-Orbit COSMO-SkyMed SAR Data Analysis

    NASA Astrophysics Data System (ADS)

    Pepe, Susi; Castaldo, Raffaele; De Luca, Claudio; Casu, Francesco; Tizzani, Pietro; Sansosti, Eugenio

    2014-05-01

    Fernandina Volcano, Galápagos (Ecuador), has experienced several uplift and eruption episodes over the last twenty-two years. The ground deformation between 2002 and 2006 was interpreted as the effect of an inflation phenomenon of two separate magma reservoirs beneath the caldera. Moreover, the uplift deformation occurred during the 2005 eruption was concentrated near the circumferential eruptive fissures, while being superimposed on a broad subsidence centred on the caldera. The geodetic studies emphasized the presence of two sub volcanic lateral intrusions from the central storage system in December 2006 and August 2007. The latest eruption in 2009 was characterized by lava flows emitted from the SW radial fissures. We analyze the spatial and temporal ground deformation between March 2012 and July 2013, by using data acquired by COSMO-SkyMed X-band constellation along both ascending and descending orbits and by applying advanced InSAR techniques. In particular, we use the SBAS InSAR approach and combine ascending and descending time series to produce vertical and East-West components of the mean deformation velocity and deformation time series. Our analysis revealed a new uplift phenomenon due to the stress concentration inside the shallow magmatic system of the volcano. In particular, the vertical mean velocity map shows that the deformation pattern is concentrated inside caldera region and is characterized by strongly radial symmetry with a maximum displacement of about 20 cm in uplift; an axial symmetry is also observed in the EW horizontal mean velocity map, showing a maximum displacement of about +12 cm towards East for the SE flank, and -12 cm towards West for the NW flank of the volcano. Moreover, the deformation time series show a rather linear uplift trend from March to September 2012, interrupted by a low deformation rate interval lasting until January 2013. After this stage, the deformation shows again a linear behaviour with an increased uplift rate

  12. Simple front tracking

    SciTech Connect

    Glimm, J.; Grove, J.W.; Li, X.; Zhao, N.

    1999-04-01

    A new and simplified front tracking algorithm has been developed as an aspect of the extension of this algorithm to three dimensions. Here the authors emphasize two main results: (1) a simplified description of the microtopology of the interface, based on interface crossings with cell block edges, and (2) an improved algorithm for the interaction of a tracked contact discontinuity with an untracked shock wave. For the latter question, they focus on the post interaction jump at the contact, which is a purely 1D issue. Comparisons to other methods, including the level set method, are included.

  13. Determination of the activation enthalpy for migration of dislocations in plastically deformed 8006 Al-alloy by positron annihilation lifetime technique

    NASA Astrophysics Data System (ADS)

    Salah, Mohammed; Abdel-Rahman, M.; Badawi, Emad A.; Abdel-Rahman, M. A.

    2016-06-01

    The activation enthalpy for migration of dislocations of plastically deformed 8006 Al-alloy was investigated by positron annihilation lifetime technique. Plastic deformation using a hydraulic press produces mainly dislocations and may produce point defects. The type of defect was studied by isochronal annealing which determines the temperature range of recovery of each type. Only one type of defect (dislocations) was observed for the investigated sample and was found to be recovered within the range 455-700 K. Isothermal annealing by slow cooling was performed through this range and used in determination of the activation enthalpy of migration of dislocations which was found to be 0.26 ± 0.01 eV.

  14. New Front End Technology

    SciTech Connect

    Pennington, D; Jovanovic, I; Comaskey, B J

    2001-02-01

    The next generation of Petawatt class lasers will require the development of new laser technology. Optical parametric chirped pulse amplification (OPCPA) holds a potential to increase the peak power level to >10 PW with existing grating technology through ultrashort pulses. Furthermore, by utilizing a new type of front-end system based on optical parametric amplification, pulses can be produced with substantially higher contrast than with Ti:sapphire regenerative amplifier technology. We performed extensive study of OPCPA using a single crystal-based OPA. We developed a replacement for Ti:sapphire regenerative amplifier for high peak power lasers based on OPCPA, with an output of 30 mJ, at 10 Hz repetition rate and 16.5 nm spectral bandwidth. We developed a 3D numerical model for OPCPA and we performed a theoretical study of influences of pump laser beam quality on optical parametric amplification. Our results indicate that OPCPA represents a valid replacement for Ti:sapphire in the front end of high energy short pulse lasers.

  15. Vehicle front wheel assist drive overspeed control system

    SciTech Connect

    Riehl, D.C.

    1987-01-13

    This patent describes a front wheel drive speed control system for a vehicle having a rear wheel drive and an assisting front wheel drive, comprising: (a) a hydraulic pump means operably connected by a hydraulic circuit to a hydraulic motor at each driven front wheel to cause rotation of that wheel; (b) an overrunning clutch assembly interposed between the motor and each associated wheel, engageable to facilitate rotation of the driven front wheel in both forward and reverse directions; (c) a speed sensing means has main rear wheel drive sensor mounted with a vehicle transmission output to the driven rear wheels thereof operable to provide pulse signals indicative of the speed of rotation of the driven rear wheels; (d) a driven front wheel sensor mounted with the vehicle and operable to provide pulse signals indicative of the speed of rotation of the driven front wheel; (e) a comparator means operable to compare the rate of rear wheel pulse signals with a first predetermined rate to produce a front wheel enabling signal when the rear wheel pulse signals are below the first predetermined rate; and (f) a front wheel drive operating circuit means connected to the comparator means to receive the front wheel enabling signal and operable to activate the hydraulic pump means to cause rotation of the front wheel.

  16. From the front

    SciTech Connect

    Price, Stephen

    2009-01-01

    The causes of recent dynamic thinning of Greenland's outlet glaciers have been debated. Realistic simulations suggest that changes at the marine fronts of these glaciers are to blame, implying that dynamic thinning will cease once the glaciers retreat to higher ground. For the last decade, many outlet glaciers in Greenland that terminate in the ocean have accelerated, thinned, and retreated. To explain these dynamic changes, two hypotheses have been discussed. Atmospheric warming has increased surface melting and may also have increased the amount of meltwater reaching the glacier bed, increasing lubrication at the base and hence the rate of glacier sliding. Alternatively, a change in the delicate balance of forces where the glacier fronts meet the ocean could trigger the changes. Faezeh Nick and colleagues5 present ice-sheet modeling experiments that mimic the observations on Helheim glacier, East Greenland, and suggest that the dynamic behaviour of outlet glaciers follows from perturbations at their marine fronts. Greenland's ice sheet loses mass partly through surface melting and partly through fast flowing outlet glaciers that connect the vast plateau of inland ice with the ocean. Earlier ice sheet models have failed to reproduce the dynamic variability exhibited by ice sheets over time. It has therefore not been possible to distinguish with confidence between basal lubrication from surface meltwater and changes at the glaciers' marine fronts as causes for the observed changes on Greenland's outlet glaciers. But this distinction bears directly on future sea-level rise, the raison d'etre of much of modern-day glaciology: If the recent dynamic mass loss Greenland's outlet glaciers is linked to changing atmospheric temperatures, it may continue for as long as temperatures continue to increase. On the other hand, if the source of the dynamic mass loss is a perturbation at the ice-ocean boundary, these glaciers will lose contact with that perturbation after a finite

  17. Structure and evolution of the northern Potwar deformed zone, Pakistan

    SciTech Connect

    Jaswal, T.M.; Lillie, R.J.; Lawrence, R.D.

    1997-02-01

    The northern Potwar deformed zone (NPDZ) is part of the active foreland fold and thrust belt of the Salt Range and Potwar Plateau in northern Pakistan. About 500 km of seismic reflection profiles are integrated with surface geologic and drilling data to examine the deformation style and structure of the NPDZ with particular emphasis on history of deformation of the Dhurnal oil field. The seismic lines suggest that the overall structure of the eastern NPDZ is a duplex structure developed beneath a passive roof thrust. The roof thrust is generated from a tipline in the Miocene Murree Formation, and the sole thrust is initiated from the same Eocambrian evaporate zone that extends 80 km southward beneath the Soan syncline and Salt Range. The Dhurnal oil field structure is a pop-up at the southern margin of the NPDZ, and developed beneath the passive roof thrust. The passive roof thrust crops out just north of Dhurnal on the steep, northern limb of the Soan syncline. An overstep passive roof thrust (Sakhwal fault) is interpreted west of Dhurnal; this fault developed due to southward progression of the deformation front beneath the earlier passive roof thrust. Very gentle basement dip and almost zero topographic slope in the NPDZ suggest that the Eocambrian salt provides effective decoupling at the present position of the NPDZ. The strong deformation in the NPDZ appears to have developed farther north, in an area where the evaporates may be lacking. Since 2 Ma, the NPDZ moved farther south over the evaporates without further deformation, whereas erosion removed any former topographic slope. Restoring a balanced cross section suggests that the minimum shortening across the NPDZ is more than 55 km. Assuming that this shortening occurred between 5.1 and 2 Ma, the shortening rate is about 18 mm/yr.

  18. Time Line Visualization of Research Fronts.

    ERIC Educational Resources Information Center

    Morris, Steven A.; Yen, G.; Wu, Zheng; Asnake, Benyam

    2003-01-01

    Research fronts, defined as clusters of documents that tend to cite a fixed, time invariant set of base documents, are plotted as time lines for visualization and exploration. Illustrates the construction, exploration, and interpretation of time lines for identifying and visualizing temporal changes in research activity through journal articles.…

  19. Laramide to Holocene structural development of the northern Colorado Front Range

    USGS Publications Warehouse

    Erslev, Eric A.; Kellogg, Karl S.; Bryant, Bruce; Ehrlich, Timothy K.; Holdaway, Steven M.; Naeser, Charles W.; Lageson, David R.; Lester, Alan

    1999-01-01

    The Rocky Mountain province of the United States is a classic basement-involved foreland orogen. Deformation during the Late Cretaceous to Eocene Laramide orogeny created an anastomosing system of basement-cored arches that bound the northern and eastern margins of the Colorado Plateau and the elliptical sedimentary basins of the Rockies. The tectonic mechanism for Laramide deformation remains controversial, with proposed mechanisms ranging from subcrustal shear during low-angle subduction (Bird, 1988, 1998; Hamilton, 1988) to detachment of the upper crust during plate collision to the west (Oldow and others, 1990; Erslev, 1993). The Rocky Mountains south of Wyoming have the additional complication of a period of mid-Tertiary igneous activity and sedimentation that coincides with Neogene extension along the Rio Grande rift. This field trip (Fig. 1) will explore the Laramide to Holocene structural development of the southern Rocky Mountains by examining the geologic record exposed in the northern Front Range of Colorado. The Front Range starts north of Canon City, Colorado, and trends north-northwest to Golden, Colorado. North of Golden, the range takes a more northerly trend toward the Wyoming border where it bifurcates into the north-trending Laramie Range (Brewer and others, 1982) and the north-northwest-trending Medicine Bow Range.

  20. Evolution of fault activity reflecting the crustal deformation: Insights from crustal stress and fault orientations in the northeast-southwest Japan

    NASA Astrophysics Data System (ADS)

    Miyakawa, A.; Otsubo, M.

    2015-12-01

    We evaluated fault activity in northeast- southwest Japan based on the regional stress and the fault orientation field for both active faults and inactive faults (here, an inactive fault is a fault which activity has not been identified in Quaternary). The regional stress field was calculated using the stress inversion method [Hardebeck and Michael, 2006] applied to earthquake focal mechanisms in the northeast-southwest Japan. The locations and orientations (i.e., strike and dip, assuming a planar fault geometry) of active faults in the study area were obtained from the Active Fault Database of Japan and inactive faults from a database compiled by Kosaka et al. [2011]. We employed slip tendency analysis [Morris et al., 1996] to evaluate the likelihood of fault slip. The values of the slip tendency is generally higher along active faults than along inactive faults. The difference between the slip tendencies of active and inactive faults reflects the difference in their activities. Furthermore the high slip tendency observed for some inactive faults suggests their high activity. These high slip tendencies imply that they have potential to be active. We propose the temporal evolution from inactive to active faulting during long-term crustal deformation to explain the potential for fault activity along inactive faults. When a region undergoes the transition from inactive to active faulting, potential active faults are observed as inactive faults with a high Part of this findig have been submitted to Tectonics (AGU Journal) (2015-07-27). We will presentate some new findings.slip tendency. The average slip tendency of inactive faults gradually increases from northeast to southwest Japan, because a relatively large number of inactive faults in southwest Japan have a high slip tendency. The representative deformation zones in Japan shows a relationship with the observed spatial variations in the evolution from inactive to active faulting. This study was supported by MEXT

  1. Bioconvection and front formation of Paramecium tetraurelia

    NASA Astrophysics Data System (ADS)

    Kitsunezaki, So; Komori, Rie; Harumoto, Terue

    2007-10-01

    We have investigated the bioconvection of Paramecium tetraurelia in high-density suspensions made by centrifugal concentration. When a suspension is kept at rest in a Hele-Shaw cell, a crowded front of paramecia is formed in the vicinity of the bottom and it propagates gradually toward the water-air interface. Fluid convection occurs under this front, and it is driven persistently by the upward swimming of paramecia. The roll structures of the bioconvection become turbulent with an increase in the depth of the suspension; they also change rapidly as the density of paramecia increases. Our experimental results suggest that lack of oxygen in the suspension causes the active individual motions of paramecia to induce the formation of this front.

  2. Nanoscale Deformable Optics

    NASA Technical Reports Server (NTRS)

    Strauss, Karl F.; Sheldon, Douglas J.

    2011-01-01

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

  3. On a front line.

    PubMed Central

    Jones, L.

    1995-01-01

    Like the patients, doctors in Sarajevo depend largely on humanitarian aid; everyone in the public sector has worked without pay for almost three years. The hospital is on a front line; yet the psychiatric department continues to function, even conducting large scale studies of psychosocial aspects of war in Bosnia-Hercegovina. The type of inpatient morbidity and treatment patterns have changed. A plethora of psychosocial rehabilitation programmes has emerged, including counselling, drop in centres, and attending to special needs of elderly people, schoolchildren, and women. The most prominent psychological symptoms were exhaustion at the prospect of a third winter of war and bewilderment at the Western stereotype of Bosnians as Muslim fundamentalists. Images p1052-a p1053-a PMID:7728062

  4. Paleoseismologic and geomorphic constraints to the deformation style and activity of the Cittanova Fault (southern Calabria, Italy)

    NASA Astrophysics Data System (ADS)

    Peronace, Edoardo; Della Seta, Marta; Fredi, Paola; Galli, Paolo; Giaccio, Biagio; Messina, Paolo; Troiani, Francesco

    2016-04-01

    The western side of Southern Calabria is the epicentral region of the strongest earthquakes of Italy. These are mainly generated by extensional faults which are still poorly investigated and/or parameterized. In this study, we explore the potential of the combined analysis of geomorphic markers, stream network morphometry and paleosimological investigations, aimed at identifying and time-constraining the surface effects of the Calabrian seismogenic faults. In this perspective, we presents results from i) plano-altimetric analysis of geomorphic markers related to active tectonics (such as marine and fluvial terraces), ii) paleoseismological investigations, and iii) time-dependent river basin and long-profile metrics of the Cittanova Fault (CF). The CF, responsible for the catastrophic Mw 7.0 earthquake of 5 February 1783, is a N220° striking, 30 km-long normal fault that downthrows the crystalline-metamorphic basement of the Aspromonte massif (~1000 m asl) below the Gioia Tauro Plain, to elevations of ~500-800 m bsl. Radiocarbon dating allowed us to ascribe the depostion of a major terraced alluvial fan (Cittanova-Taurianova terrace, TAC) to the early Last Glacial Maximum (LGM) and to date the avulsion of the depositional top surface of TAC to 28 ka. As we have found remnants of the TAC also in the CF footwall offset by 12-17 m, we estimate a vertical slip rate of 0.6 ± 0.1 mm/yr for the past 28 ka. Paleoseismological data across the fault scarp evidenced at least three surface ruptures associated to ~Mw 7.0 paleoearthquakes prior to the 1783 event. The recurrence time (~3.2 kyr) is rather longer than other Apennine normal faults (0.3-2.4 kyr), whereas it is consistent with the low slip rate of CF for the late Upper Pleistocene (0.6 mm/yr). On a longer time scale, the spatial configuration of river basin morphometry evidenced the morphodynamic rensponse to the higher slip in the central sector of CF. Furthermore, long-profile metrics, and in particular the spatial

  5. Holocene soft-sediment deformation of the Santa Fe-Sopetrán Basin, northern Colombian Andes: Evidence for pre-Hispanic seismic activity?

    NASA Astrophysics Data System (ADS)

    Suter, F.; Martínez, J. I.; Vélez, M. I.

    2011-04-01

    The detailed study of four deformed intervals from the Holocene fluvio-lacustrine deposits of the Santa Fe-Sopetrán Basin in northern Colombia shows 17 types of soft-sediment deformation (SSD) structures. Evidence indicates that seismic activity was responsible for the SSD structures, a conclusion reached after considering the environmental conditions at the time of sediment deposition and shortly after, and the detailed analysis of the driving force systems. Other triggers (i.e. overloading and rapid sedimentation), however, are not discarded. Intervals showing SSD structures occurred at centennial frequencies and apparently resulted from Mw 6-7 earthquakes. The Holocene age of these major shaking events should be seriously considered when evaluating the seismic hazard and risk for the middle Cauca Valley and the nearby city of Medellín with 3 million inhabitants.

  6. Imaging active faulting in a region of distributed deformation from the joint clustering of focal mechanisms and hypocentres: Application to the Azores-western Mediterranean region

    NASA Astrophysics Data System (ADS)

    Custódio, Susana; Lima, Vânia; Vales, Dina; Cesca, Simone; Carrilho, Fernando

    2016-04-01

    The matching between linear trends of hypocentres and fault planes indicated by focal mechanisms (FMs) is frequently used to infer the location and geometry of active faults. This practice works well in regions of fast lithospheric deformation, where earthquake patterns are clear and major structures accommodate the bulk of deformation, but typically fails in regions of slow and distributed deformation. We present a new joint FM and hypocentre cluster algorithm that is able to detect systematically the consistency between hypocentre lineations and FMs, even in regions of distributed deformation. We apply the method to the Azores-western Mediterranean region, with particular emphasis on western Iberia. The analysis relies on a compilation of hypocentres and FMs taken from regional and global earthquake catalogues, academic theses and technical reports, complemented by new FMs for western Iberia. The joint clustering algorithm images both well-known and new seismo-tectonic features. The Azores triple junction is characterised by FMs with vertical pressure (P) axes, in good agreement with the divergent setting, and the Iberian domain is characterised by NW-SE oriented P axes, indicating a response of the lithosphere to the ongoing oblique convergence between Nubia and Eurasia. Several earthquakes remain unclustered in the western Mediterranean domain, which may indicate a response to local stresses. The major regions of consistent faulting that we identify are the mid-Atlantic ridge, the Terceira rift, the Trans-Alboran shear zone and the north coast of Algeria. In addition, other smaller earthquake clusters present a good match between epicentre lineations and FM fault planes. These clusters may signal single active faults or wide zones of distributed but consistent faulting. Mainland Portugal is dominated by strike-slip earthquakes with fault planes coincident with the predominant NNE-SSW and WNW-ESE oriented earthquake lineations. Clusters offshore SW Iberia are

  7. Interactions between thin- and thick-skinned tectonics at the northwestern front of the Jura fold-and-thrust belt (eastern France)

    NASA Astrophysics Data System (ADS)

    Madritsch, Herfried; Schmid, Stefan M.; Fabbri, Olivier

    2008-10-01

    This study investigates spatial and temporal interactions of thin- and thick-skinned tectonics in a classical foreland setting located at the front of the Jura fold-and-thrust belt in eastern France. The working area coincides with the intracontinental Rhine-Bresse Transfer Zone and represents the most external front of the deformed Alpine foreland. The investigation combines analyses of largely unpublished and newly available subsurface information with our own structural data, including an exhaustive paleostress analysis and geomorphologic observations. Results are provided in the form of a new tectonic map and a series of regional cross sections through the study area. The Besançon Zone, forming the most external part of the thin-skinned fold-and-thrust belt, encroached onto the Eo-Oligocene Rhine-Bresse Transfer Fault System until early Pliocene times. Thrust propagation was largely controlled by the Late Paleozoic to Paleogene preexisting fault pattern that characterizes the Rhine-Bresse Transfer Zone. Thick-skinned deformation, dominant throughout the Avant-Monts Zone located farther to the west, was associated with compressional to transpressional reactivation of such faults. Overprinting and crosscutting criteria of fault slip data allow distinguishing between systematically fanning maximum horizontal stress axes that define the front of the thin-skinned Jura fold-and-thrust belt and consistently NW-SE directed maximum horizontal stress axes that characterize deformation of the autochthonous cover of the foreland, which is affected by thick-skinned tectonics. Tectonic and geomorphic analyses indicate that thick-skinned tectonics started at a very late stage of foreland deformation (post-early Pliocene). Geomorphic observations imply that deformation between Mesozoic cover and basement is locally still decoupled. However, overprinting relationships and recent seismicity suggest that present-day tectonic activity is thick skinned, which probably reflects

  8. FACILITY 1042. FRONT OBLIQUE SHOWING ROYAL PALMS LINING FRONT WALK. ...

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

    FACILITY 1042. FRONT OBLIQUE SHOWING ROYAL PALMS LINING FRONT WALK. VIEW FACING SOUTHEAST - U.S. Naval Base, Pearl Harbor, Naval Housing Area Hale Alii, Junior Officers' Quarters Type, 9-10 Hale Alii Avenue, 1-2 Eighth Street, Pearl City, Honolulu County, HI

  9. Plate description of active deformation in the Africa (AF)-Arabia (AR)-Eurasia (EU) zone of plate interaction

    NASA Astrophysics Data System (ADS)

    Vernant, P.; McClusky, S.; Reilinger, R.

    2006-12-01

    We present the results of 17 years of GPS monitoring in this zone of plate interaction and show that to the resolution of our observations (i.e., ~1-2 mm/yr; ~ ±10 % of relative plate motions), deformation is consistent with plate-block models with relative motion between adjacent plates/blocks accommodated by elastic strain accumulation. Relative plate motions are consistent with geologically recent (~ 3 Ma) plate motions where geologic estimates of relative plate motion have been determined (AR- Nubia: Red Sea; AR-Somalia: Gulf of Aden; AF-EU; AR-EU). Furthermore, fault slip rates derived from the GPS block motions are mostly equal to geologic slip rates determined for long enough time intervals to average out earthquake cycle effects. We conclude that a plate description (i.e., relative Euler vectors) is appropriate to describe the kinematics of continental deformation during the past few Myr in this zone of plate interaction.

  10. Volcano Deformation and Modeling on Active Volcanoes in the Philippines from ALOS InSAR Time Series

    NASA Astrophysics Data System (ADS)

    Morales Rivera, Anieri M.; Amelung, Falk; Eco, Rodrigo

    2015-05-01

    Bulusan, Kanlaon, and Mayon volcanoes have erupted over the last decade, and Taal caldera showed signs of volcanic unrest within the same time range. Eruptions at these volcanoes are a threat to human life and infrastructure, having over 1,000,000 people living within 10 km from just these 4 volcanic centers. For this reason, volcano monitoring in the Philippines is of extreme importance. We use the ALOS-1 satellite from the Japanese Aerospace Exploration Agency (JAXA) to make an InSAR time series analysis over Bulusan, Kanlaon, Mayon, and Taal volcanoes for the 2007-2011 period. Time-dependent deformation was detected at all of the volcanoes. Deformation related to changes in pressurization of the volcanic systems was found on Taal caldera and Bulusan volcanoes, with best fitting Mogi sources located at half-space depths of 3.07 km and 0.5 km respectively.

  11. Active crustal deformation across the Basin and Range province, western United States, measured with the Global Positioning System, 1992-2002

    NASA Astrophysics Data System (ADS)

    Hammond, W.; Thatcher, W.

    2003-04-01

    The Basin and Range province of the western United States is a region of active tectonic extension and dextral shear, accommodating roughly 25% of the motion between non-deforming North America (NA) and the Pacific Plate (PA). The orientation of dextral shear is consistent with that of NA/PA relative plate motion, suggesting that this high elevation interior province is an important part of the plate boundary system. We present an analysis of Global Positioning System (GPS) data collected from 1992 to 2002. An 800 km long network of campaign-style geodetic benchmarks extends from east of the Wasatch fault zone (WFZ) in central Utah to west of the Genoa fault zone and Lake Tahoe in the northern Sierra Nevada mountains. From the new data collected in September 2002 and from data collected in 1992, 1996, and 1998, velocities have been estimated at 92 GPS sites, nearly double the number previously presented by Thatcher et al. [1999]. This new data reduces the uncertainty in site velocities and increases the spatial detail compared to earlier results, and now allows resolution of distinct domains in the tensor strain rate field. To process the data we use the GIPSY/OASIS and Quasi-Observation Combination Analysis (Dong et al. [1998]) software packages and incorporate data from continuously recording GPS stations in California and Nevada. The results show that most of the approximately 12 mm/yr of Sierra Nevada block motion is accommodated by right lateral shear and extensional deformation concentrated in the westernmost 200 km of Nevada, in the vicinity of the Walker Lane (WL). A lesser amount of velocity variation (roughly 3 mm/yr) is localized at the easternmost edge of the network, in the vicinity of the Wasatch Fault Zone (WFZ). Estimates of tensor strain rates show transitions in the style of deformation. Near the WFZ only uniaxial, roughly east-west extension can be resolved. Between longitude -112 and -117.5 no deformation is resolvable. Near longitude -118, in

  12. Shack Hartmann wave-front measurement with a large F-number plastic microlens array

    NASA Astrophysics Data System (ADS)

    Yoon, Geun Young; Jitsuno, Takahisa; Nakatsuka, Masahiro; Nakai, Sadao

    1996-01-01

    A new plastic microlens array, consisting of 900 lenslets, has been developed for the Shack Hartmann wave-front sensor. The individual lens, is 300 mu m \\times 300 mu m and has a focal length of 10 mm, which provides the same focal size, 60 mu m in diameter, with a constant peak intensity. One can improve the wave-front measurement accuracy by reducing the spot centroiding error by averaging a few frame memories of an image processor. A deformable mirror for testing the wave-front sensor gives an appropriate defocus and astigmatism, and the laser wave front is measured with a Shack Hartmann wave-front sensor. The measurement accuracy and reproducibility of our wave-front sensor are better than lambda /20 and lambda /50 ( lambda = 632.8 nm), respectively, in rms.

  13. Surface properties of ocean fronts

    NASA Technical Reports Server (NTRS)

    Wolff, P. M.; Hubert, W. E.

    1976-01-01

    Background information on oceanic fronts is presented and the results of several models which were developed to study the dynamics of oceanic fronts and their effects on various surface properties are described. The details of the four numerical models used in these studies are given in separate appendices which contain all of the physical equations, program documentation and running instructions for the models.

  14. Snowplow Injection Front Effects

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Chandler, M. O.; Buzulukova, N.; Collinson, G. A.; Kepko, E. L.; Garcia-Sage, K. S.; Henderson, M. G.; Sitnov, M. I.

    2013-01-01

    As the Polar spacecraft apogee precessed through the magnetic equator in 2001, Polar encountered numerous substorm events in the region between geosynchronous orbit and 10 RE geocentric distance; most of them in the plasma sheet boundary layers. Of these, a small number was recorded near the neutral sheet in the evening sector. Polar/Thermal Ion Dynamics Experiment provides a unique perspective on the lowest-energy ion plasma, showing that these events exhibited a damped wavelike character, initiated by a burst of radially outward flow transverse to the local magnetic field at approximately 80 km/s. They then exhibit strongly damped cycles of inward/outward flow with a period of several minutes. After one or two cycles, they culminated in a hot plasma electron and ion injection, quite similar to those observed at geosynchronous orbit. Cold plasmaspheric plasmas comprise the outward flow cycles, while the inward flow cycles contain counterstreaming field-parallel polar wind-like flows. The observed wavelike structure, preceding the arrival of an earthward moving substorm injection front, suggests an outward displacement driven by the inward motion at local times closer to midnight, that is, a "snowplow" effect. The damped in/out flows are consistent with interchange oscillations driven by the arrival at the observed local time by an injection originating at greater radius and local time.

  15. Fronts in Large Marine Ecosystems

    NASA Astrophysics Data System (ADS)

    Belkin, Igor M.; Cornillon, Peter C.; Sherman, Kenneth

    2009-04-01

    Oceanic fronts shape marine ecosystems; therefore front mapping and characterization are among the most important aspects of physical oceanography. Here we report on the first global remote sensing survey of fronts in the Large Marine Ecosystems (LME). This survey is based on a unique frontal data archive assembled at the University of Rhode Island. Thermal fronts were automatically derived with the edge detection algorithm of Cayula and Cornillon (1992, 1995, 1996) from 12 years of twice-daily, global, 9-km resolution satellite sea surface temperature (SST) fields to produce synoptic (nearly instantaneous) frontal maps, and to compute the long-term mean frequency of occurrence of SST fronts and their gradients. These synoptic and long-term maps were used to identify major quasi-stationary fronts and to derive provisional frontal distribution maps for all LMEs. Since SST fronts are typically collocated with fronts in other water properties such as salinity, density and chlorophyll, digital frontal paths from SST frontal maps can be used in studies of physical-biological correlations at fronts. Frontal patterns in several exemplary LMEs are described and compared, including those for: the East and West Bering Sea LMEs, Sea of Okhotsk LME, East China Sea LME, Yellow Sea LME, North Sea LME, East and West Greenland Shelf LMEs, Newfoundland-Labrador Shelf LME, Northeast and Southeast US Continental Shelf LMEs, Gulf of Mexico LME, and Patagonian Shelf LME. Seasonal evolution of frontal patterns in major upwelling zones reveals an order-of-magnitude growth of frontal scales from summer to winter. A classification of LMEs with regard to the origin and physics of their respective dominant fronts is presented. The proposed classification lends itself to comparative studies of frontal ecosystems.

  16. Pulsed Episodes of Shortening Within the Tian Shan Foreland: Implications for Deformation Rate Interpretations Throughout Central Asia

    NASA Astrophysics Data System (ADS)

    Heermance, R. V.; Burbank, D. W.; Chen, J.

    2007-12-01

    Unsteadiness in short-term deformation, such as earthquake clustering or development of new faults in lieu of deformation on older structures, poses problems when trying to develop an appropriate context (e.g. regional tectonic rates and active structures) for assessing seismic risk. Here we show that a similar unsteadiness can be found on an orogen scale at million-year time scales, and suggest spatial heterogeneity of deformation rates are a fundamental part of mountain-building in central Asia. The Tian Shan are an intracontinental mountain range that formed north of the Himalayan orogen but in response to the ongoing Indo-Asian collision. Although continuous since the early Miocene, deformation has occurred in an erratic sequence that suggests deformation rates are not constant within the foreland. In order to reconstruct a detailed history of foreland deformation bounding the southern Tian Shan in western China, we have synthesized extensive mapping, analysis of seismic sections, magnetostratigraphy of the foreland fill and associated growth strata, apatite fission-track dating, and changes in sediment-accumulation rates from the >6500 km2 Kashi basin. Three cross-sections spaced along a 55-km-wide, E-W section of the range-front document variable shortening from 11 to 31 km since the initiation of uplift, of which 7-12 km occurred since ~4 Ma. Both overall shortening and total shortening rates throughout the Miocene decrease towards the east, but match the expected differences in magnitude due to 0.7°/M.y clockwise rotation of the Tarim basin around a pole at 93°E, 37°N (Thatcher, W., 2007, JGR 112: B01401). Temporal constraints on individual structures, however, document at least four distinct stages of deformation. Initial uplift (stage 1) of hinterland structures began at 20-25 Ma. Stage 2 occurred at ~16.3 Ma when the basement-involved deformation front stepped south to the Kashi Basin thrust that bounds the foredeep strata. Stage 3 occurred from ~14

  17. Constraining fault activity by investigating tectonically-deformed Quaternary palaeoshorelines using a synchronous correlation method: the Capo D'Orlando Fault as a case study (NE Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Meschis, Marco; Roberts, Gerald P.; Robertson, Jennifer

    2016-04-01

    Long-term curstal extension rates, accommodated by active normal faults, can be constrained by investigating Late Quaternary vertical movements. Sequences of marine terraces tectonically deformed by active faults mark the interaction between tectonic activity, sea-level changes and active faulting throughout the Quaternary (e.g. Armijo et al., 1996, Giunta et al, 2011, Roberts et al., 2013). Crustal deformation can be calculated over multiple seismic cycles by mapping Quaternary tectonically-deformed palaeoshorelines, both in the hangingwall and footwall of active normal faults (Roberts et al., 2013). Here we use a synchronous correlation method between palaeoshorelines elevations and the ages of sea-level highstands (see Roberts et al., 2013 for further details) which takes advantage of the facts that (i) sea-level highstands are not evenly-spaced in time, yet must correlate with palaeoshorelines that are commonly not evenly-spaced in elevation, and (ii) that older terraces may be destroyed and/or overprinted by younger highstands, so that the next higher or lower paleoshoreline does not necessarily correlate with the next older or younger sea-level highstand. We investigated a flight of Late Quaternary marine terraces deformed by normal faulting as a result of the Capo D'Orlando Fault in NE Sicily (e.g. Giunta et al., 2011). This fault lies within the Calabrian Arc which has experienced damaging seismic events such as the 1908 Messina Straits earthquake ~ Mw 7. Our mapping and previous mapping (Giunta et al. (2011) demonstrate that the elevations of marine terraces inner edges change along the strike the NE - SW oriented normal fault. This confirms active deformation on the Capo D'Orlando Fault, strongly suggesting that it should be added into the Database of Individual Seismogenic Sources (DISS, Basili et al., 2008). Giunta et al. (2011) suggested that uplift rates and hence faults lip-rates vary through time for this examples. We update the ages assigned to

  18. 6. OVERALL VIEW OF THE FRONT AND THE TOWER, LOOKING ...

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

    6. OVERALL VIEW OF THE FRONT AND THE TOWER, LOOKING WEST FROM THE ACTIVE PIER OF BAY SHIP AND YACHT COMPANY. COAST GUARD CUTTER SHERMAN AT RIGHT. - United Engineering Company Shipyard, Crane, 2900 Main Street, Alameda, Alameda County, CA

  19. Convective dynamics of traveling autocatalytic fronts in a modulated gravity field.

    PubMed

    Horváth, Dezső; Budroni, Marcello A; Bába, Péter; Rongy, Laurence; De Wit, Anne; Eckert, Kerstin; Hauser, Marcus J B; Tóth, Ágota

    2014-12-21

    When traveling in thin solution layers, autocatalytic chemical fronts may be deformed and accelerated by convective currents that develop because of density and surface tension gradients related to concentration and thermal gradients across the front. On earth, both buoyancy and Marangoni related flows can act in solution layers open to the air while only buoyancy effects operate in covered liquid layers. The respective effects of density and surface tension induced convective motions are analysed here by studying experimentally the propagation of autocatalytic fronts in uncovered and covered liquid layers during parabolic flights in which the gravity field is modulated periodically. We find that the velocity and deformation of the front are increased during hyper-gravity phases and reduced in the micro-gravity phase. The experimental results compare well with numerical simulations of the evolution of the concentration of the autocatalytic product coupled to the flow field dynamics described by Navier-Stokes equations.

  20. Improving the mechanical properties of Zr-based bulk metallic glass by controlling the activation energy for β-relaxation through plastic deformation

    SciTech Connect

    Adachi, Nozomu; Todaka, Yoshikazu Umemoto, Minoru; Yokoyama, Yoshihiko

    2014-09-29

    The mechanism of plastic deformation in bulk metallic glasses (BMGs) is widely believed to be based on a shear transformation zone (STZ). This model assumes that a shear-induced atomic rearrangement occurs at local clusters that are a few to hundreds of atoms in size. It was recently postulated that the potential energy barrier for STZ activation, W{sub STZ}, calculated using the cooperative shear model, is equivalent to the activation energy for β-relaxation, E{sub β}. This result suggested that the fundamental process for STZ activation is the mechanically activated β-relaxation. Since the E{sub β} value and the glass transition temperature T{sub g} of BMGs have a linear relation, that is, because E{sub β} ≈ 26RT{sub g}, the composition of the BMG determines the ease with which the STZ can be activated. Enthalpy relaxation experiments revealed that the BMG Zr{sub 50}Cu{sub 40}Al{sub 10} when deformed by high-pressure torsion (HPT) has a lower E{sub β} of 101 kJ/mol. The HPT-processed samples accordingly exhibited tensile plastic elongation (0.34%) and marked decreases in their yield strength (330 MPa). These results suggest that mechanically induced structural defects (i.e., the free volume and the anti-free volume) effectively act to reduce W{sub STZ} and increase the number of STZs activated during tensile testing to accommodate the plastic strain without requiring a change in the composition of the BMG. Thus, this study shows quantitatively that mechanically induced structural defects can overcome the compositional limitations of E{sub β} (or W{sub STZ}) and result in improvements in the mechanical properties of the BMG.

  1. Can deep seated gravitational slope deformations be activated by regional tectonic strain: First insights from displacement measurements in caves from the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Baroň, Ivo; Plan, Lukas; Grasemann, Bernhard; Mitroviċ, Ivanka; Lenhardt, Wolfgang; Hausmann, Helmut; Stemberk, Josef

    2016-04-01

    Tectonic elastic strain and ground deformations are documented as the most remarkable environmental phenomena occurring prior to local earthquakes in tectonically active areas. The question arises if such strain would be able to trigger mass movements. We discuss a directly observed fault slip and a subsequent minor activation of a deep-seated gravitational slope deformation prior to the M = 3 Bad Fischau earthquake between end of November and early December 2013 in NE Austria. The data originate from two faults in the Emmerberg and Eisenstein Caves in the transition zone between the Eastern Alps and the Vienna Basin, monitored in the framework of the FWF "Speleotect" project. The fault slips have been observed at the micrometer-level by means of an opto-mechanical 3D crack gauge TM-71. The discussed event started with the fault activation in the Emmerberg Cave on 25 November 2013 recorded by measurements of about 2 μm shortening and 1 μm sinistral parallel slip, which was fully in agreement with the macroscopically documented past fault kinematics. One day later, the mass (micro) movement activated on the opposite side of the mountain ridge in the Eisenstein Cave and it continued on three consecutive days. Further, the fault in the Emmerberg Cave experienced also a subsequent gravitational relaxation on 2/3 December 2013, when the joint opened and the southern block subsided towards the valley, while the original sinistral displacement remained irreversible. The process was followed by the M = 3 earthquake in Bad Fischau on 11 December 2013. Our data suggest that tectonic strain could play a higher role on the activation of slow mass movements in the area than expected. Although we cannot fully exclude the co-activation of the mass movement in the Eisenstein Cave by water saturation, the presented data bring new insight into recent geodynamics of the Eastern Alps and the Vienna Basin. For better interpretations and conclusions however, we need a much longer

  2. An explanation of unstable wetting fronts in soils

    NASA Astrophysics Data System (ADS)

    Steenhuis, Tammo; Parlange, Jean-Yves; Kung, Samuel; Stoof, Cathelijne; Baver, Christine

    2016-04-01

    Despite the findings of Raats on unstable wetting front almost a half a century ago, simulating wetting fronts in soils is still an area of active research. One of the critical questions currently is whether Darcy law is valid at the wetting front. In this talk, we pose that in many cases for dry soils, Darcy's law does not apply because the pressure field across the front is not continuous. Consequently, the wetting front pressure is not dependent on the pressure ahead of the front but is determined by the radius of water meniscuses and the dynamic contact angle of the water. If we further assume since the front is discontinuous, that water flows at one pore at the time, then by using the modified Hoffman relationship - relating the dynamic contact angle to the pore water velocity - we find the elevated pressures at the wetting front typical for unstable flows that are similar to those observed experimentally in small diameter columns. The theory helps also explain the funnel flow phenomena observed in layered soils.

  3. Distribution of the Late-Quaternary deformation in Northwestern Himalaya

    NASA Astrophysics Data System (ADS)

    Vassallo, R.; Mugnier, J.-L.; Vignon, V.; Malik, M. A.; Jayangondaperumal, R.; Srivastava, P.; Jouanne, F.; Carcaillet, J.

    2015-02-01

    Three main Cenozoic thrusts at the front of Northwestern Himalaya have accommodated most of the India-Eurasia convergence across the belt over the last million years and produced the present relief. Their recent tectonic activity is poorly known because of the long period of inaccessibility of the Jammu and Kashmir state, and because the latest and only large earthquake recorded in the region occurred in 1555 AD. We show where the deformation is localized during the Late-Quaternary, and determine shortening rates across the structures by analyzing the geometry and chronology of geomorphic markers. The Main Boundary Thrust in this region ceased moving at least ∼30 ka ago. On the contrary, the more external Medlicott-Wadia Thrust and Main Frontal Thrust, both merging at depth on the sub-flat detachment of the Main Himalayan Thrust, exhibit hectometric-scale deformations accumulated during the last thousands of years. The total shortening rate absorbed by these faults over the last 14-24 ka is between 13.2 and 27.2 mm/yr (11.2 ± 3.8 and 9.0 ± 3.2 mm /yr, respectively). Part of this deformation may be associated to the geometry of the Chenab reentrant, which could generate an extra oblique component. However, the lower bound of our shortening rates is consistent with previously determined geodetic rates. Active deformation on these structures follows an in-sequence/out-of-sequence pattern, with breaking of both ramps being possible for earthquakes triggered on the main detachment.

  4. Radiative magnetized thermal conduction fronts

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The evolution of plane-parallel magnetized thermal conduction fronts in the interstellar medium (ISM) was studied. Separating the coronal ISM phase and interstellar clouds, these fronts have been thought to be the site of the intermediate-temperature regions whose presence was inferred from O VI absorption-line studies. The front evolution was followed numerically, starting from the initial discontinuous temperature distribution between the hot and cold medium, and ending in the final cooling stage of the hot medium. It was found that, for the typical ISM pressure of 4000 K/cu cm and the hot medium temperature of 10 to the 6th K, the transition from evaporation to condensation in a nonmagnetized front occurs when the front thickness is 15 pc. This thickness is a factor of 5 smaller than previously estimated. The O VI column densities in both evaporative and condensation stages agree with observations if the initial hot medium temperature Th exceeds 750,000 K. Condensing conduction fronts give better agreement with observed O VI line profiles because of lower gas temperatures.

  5. Restless rays, steady wave fronts.

    PubMed

    Godin, Oleg A

    2007-12-01

    Observations of underwater acoustic fields with vertical line arrays and numerical simulations of long-range sound propagation in an ocean perturbed by internal gravity waves indicate that acoustic wave fronts are much more stable than the rays comprising these wave fronts. This paper provides a theoretical explanation of the phenomenon of wave front stability in a medium with weak sound-speed perturbations. It is shown analytically that at propagation ranges that are large compared to the correlation length of the sound-speed perturbations but smaller than ranges at which ray chaos develops, end points of rays launched from a point source and having a given travel time are scattered primarily along the wave front corresponding to the same travel time in the unperturbed environment. The ratio of root mean square displacements of the ray end points along and across the unperturbed wave front increases with range as the ratio of ray length to correlation length of environmental perturbations. An intuitive physical explanation of the theoretical results is proposed. The relative stability of wave fronts compared to rays is shown to follow from Fermat's principle and dimensional considerations. PMID:18247745

  6. The Front of the Aar Massif: A Crustal-Scale Ramp Anticline?

    NASA Astrophysics Data System (ADS)

    Herwegh, Marco; Mock, Samuel; Wehrens, Philip; Baumberger, Roland; Berger, Alfons; Wangenheim, Cornelia; Glotzbach, Christoph; Kissling, Edi

    2015-04-01

    The front of the Aar Massif (Swiss Central Alps) is characterized by Paleozoic basement rocks exposed at altitudes of more than 4600m above sea level, followed by a steeply north dipping Mesozoic sedimentary cover and overlying Helvetic nappes. The sediments turn into subhorizontal orientations just few kilometers to the N, where the top of the basement is situated at depths of about 7000m below sea level. What is the origin of this vertical jump of about 12000m of the basement rocks over such short horizontal distances? Recent structural investigations at the Basement-Cover contact indicate a complex structural evolution involving reactivation of extensional faults and inversion of half-grabens during early compressional stages. In the internal parts of the Aar Massif a general steepening of the faults resulted with progressive compression. In the northern frontal part, however, a new spaced cleavage evolved, which is dipping with 20-30° to the SE. In places, the new cleavage in the basement rocks is intense and pervasive and correlates with a steepening of the basement-cover contact and its offsets of several tens to hundreds of meters. Hence strain is strongly partitioned in a large number of high strain zones, which cover a cumulative thickness of at least 2000m, eventually even much more considering subsurface continuation. The Mesozoic sediments affected by this large-scale deformation zone are either intensely ductile folded in the case of limestones or faulted and imbricated in the case of dolomites. These differences in deformation style result from the deformation conditions of about < 250-300°C, where calcite still deforms in a ductile manner, while dolomite and crystalline basement preferentially undergo brittle deformation in combination of dissolution-precipitation processes. In a large-scale point of view, we suggest that the high strain domain in the crystalline basement in fact represents a crustal-scale several kilometers wide shear zone, which

  7. Io in Front of Jupiter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope.

    Images from Cassini that will be released over the next several days capture each of the four Galilean satellites in their orbits around the giant planet.

    This true-color composite frame, made from narrow angle images taken on Dec. 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers (12.1 million miles). The image scale is 117 kilometers (73 miles) per pixel.

    The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks.

    Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

  8. Pentan isomers compound flame front structure

    SciTech Connect

    Mansurov, Z.A.; Mironenko, A.W.; Bodikov, D.U.; Rachmetkaliev, K.N.

    1995-08-13

    The fuels (hexane, pentane, diethyl ether) and conditions investigated in this study are relevant to engine knock in spark- ignition engines. A review is provided of the field of low temperature hydrocarbon oxidation. Studies were made of radical and stable intermediate distribution in the front of cool flames: Maximum concentrations of H atoms and peroxy radicals were observed in the luminous zone of the cool flame front. Peroxy radicals appear before the luminous zone at 430 K due to diffusion. H atoms were found in cool flames of butane and hexane. H atoms diffuses from the luminous zone to the side of the fresh mixture, and they penetrate into the fresh mixture to a small depth. Extension of action sphear of peroxy radicals in the fresh mixture is much greater than that of H atoms due to their small activity and high concentrations.

  9. Electromagnetic energy conversion at reconnection fronts.

    PubMed

    Angelopoulos, V; Runov, A; Zhou, X-Z; Turner, D L; Kiehas, S A; Li, S-S; Shinohara, I

    2013-09-27

    Earth's magnetotail contains magnetic energy derived from the kinetic energy of the solar wind. Conversion of that energy back to particle energy ultimately powers Earth's auroras, heats the magnetospheric plasma, and energizes the Van Allen radiation belts. Where and how such electromagnetic energy conversion occurs has been unclear. Using a conjunction between eight spacecraft, we show that this conversion takes place within fronts of recently reconnected magnetic flux, predominantly at 1- to 10-electron inertial length scale, intense electrical current sheets (tens to hundreds of nanoamperes per square meter). Launched continually during intervals of geomagnetic activity, these reconnection outflow flux fronts convert ~10 to 100 gigawatts per square Earth radius of power, consistent with local magnetic flux transport, and a few times 10(15) joules of magnetic energy, consistent with global magnetotail flux reduction. PMID:24072917

  10. Electromagnetic energy conversion at reconnection fronts.

    PubMed

    Angelopoulos, V; Runov, A; Zhou, X-Z; Turner, D L; Kiehas, S A; Li, S-S; Shinohara, I

    2013-09-27

    Earth's magnetotail contains magnetic energy derived from the kinetic energy of the solar wind. Conversion of that energy back to particle energy ultimately powers Earth's auroras, heats the magnetospheric plasma, and energizes the Van Allen radiation belts. Where and how such electromagnetic energy conversion occurs has been unclear. Using a conjunction between eight spacecraft, we show that this conversion takes place within fronts of recently reconnected magnetic flux, predominantly at 1- to 10-electron inertial length scale, intense electrical current sheets (tens to hundreds of nanoamperes per square meter). Launched continually during intervals of geomagnetic activity, these reconnection outflow flux fronts convert ~10 to 100 gigawatts per square Earth radius of power, consistent with local magnetic flux transport, and a few times 10(15) joules of magnetic energy, consistent with global magnetotail flux reduction.

  11. Deformable mirror with combined piezoelectric and electrostatic actuators

    NASA Astrophysics Data System (ADS)

    Merkle, F.; Freischlad, K.; Reischmann, H.-L.

    1982-10-01

    An adaptive optics system with modal phase correction for reconstituting astronomical images passing through the atmosphere is described. An active mirror in a gimbal mount houses an electrostatic deformable membrane for the modal corrections. Piezoelectric actuators are attached behind the mirror for tilt correction. Wavefronts triggering the electrode detectors in the mirror also result in generation of a map of the wave-front errors. Compensating phase distributions for successive waves are calculated automatically by an expansion of the phase distortions into modes of a set of basis functions. Turbulence compensation is accomplished with Zernike polynomials if only a small number of modes is present, while Karhunen-Loeve functions serve for any number of modes. Phase aberrations are detected by diode arrays connected to amplifier tubes. Actual measurement of the wavefront phase is performed by a shearing interferometer and by use of an iterative algorithm to assay the intensity distribution of the image.

  12. The Front Line.

    ERIC Educational Resources Information Center

    Unks, Gerald

    1979-01-01

    The author draws an analogy between today's school system and an assembly line, deploring the notion that all children are taught the same thing at the same time, ending in humiliation, disgrace, and failure for some, and nonchallenging academic activities for others. (KC)

  13. Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.; Cortés, José M.; Terrizzano, Carla M.

    2016-05-01

    Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to ~450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene-lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N-S stretching direction, subparallel to the strike of the main fault.

  14. Instability of evaporation fronts in the interstellar medium

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae E-mail: wkim@astro.snu.ac.kr

    2013-12-10

    The neutral component of the interstellar medium is segregated into the cold neutral medium (CNM) and warm neutral medium (WNM) as a result of thermal instability. It was found that a plane-parallel CNM-WNM evaporation interface, across which the CNM undergoes thermal expansion, is linearly unstable to corrugational disturbances, in complete analogy with the Darrieus-Landau instability (DLI) of terrestrial flames. We perform a full linear stability analysis as well as nonlinear hydrodynamic simulations of the DLI of such evaporation fronts in the presence of thermal conduction. We find that the DLI is suppressed at short length scales by conduction. The length and time scales of the fastest growing mode are inversely proportional to the evaporation flow speed of the CNM and its square, respectively. In the nonlinear stage, the DLI saturates to a steady state where the front deforms to a finger-like shape protruding toward the WNM, without generating turbulence. The evaporation rate at nonlinear saturation is larger than the initial plane-parallel value by a factor of ∼2.4 when the equilibrium thermal pressure is 1800 k {sub B} cm{sup –3} K. The degrees of front deformation and evaporation-rate enhancement at nonlinear saturation are determined primarily by the density ratio between the CNM and WNM. We demonstrate that the Field length in the thermally unstable medium should be resolved by at least four grid points to obtain reliable numerical outcomes involving thermal instability.

  15. Active microrheology of entangled blends of DNA and Actin link polymer flexibility to induced molecular deformations and stress propagation

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Robert; Robertson-Anderson, Rae; Anderson Research Team

    Actin is a ubiquitous structural protein in the cytoskeleton that gives cells shape and rigidity, and plays important roles in mechanical processes such as cell motility and division. Actin's diverse roles stem from its ability to polymerize into semiflexible filaments that are less than one persistence length (17 µm) in length, and form entangled networks that display unique viscoelastic properties. We previously found that entangled actin networks propagate microscale forces over several persistence lengths (>60 m) and takes minutes to relax. DNA, oppositely, has thousands of persistence lengths (50 nm) per chain, exhibits minimal force propagation, and takes only seconds to re-equilibrate. To directly determine the role of flexibility in mechanical response and force propagation of entangled networks, we use optical tweezers and fluorescence microscopy to investigate blends of actin and DNA. We use optically driven microspheres to perturb the network far from equilibrium and measure the force the network creates in response to the induced force. We simultaneously track partially labeled actin filaments during the perturbation and subsequent relaxation period. We characterize filament deformation and show explicitly how induced microscale forces propagate through the network.

  16. An array method for detection, location and characterization of multi-scale seismic energy release associated to the deformation processes of active subduction zones

    NASA Astrophysics Data System (ADS)

    Poiata, N.; Satriano, C.; Bernard, P.; Vilotte, J.; Obara, K.

    2013-12-01

    Detection, location and characterization of the seismic energy release associated to deformation processes in active subduction zones are fundamental for understanding the dynamics of active deformation and the mechanisms of generation and rupturing of large subduction earthquakes. The statistical analysis of this seismic energy release, spanning a wide range of space and time scales, as well as phenomena, (e.g., earthquakes, seismic repeaters, low and very low-frequency earthquakes, tectonic tremors) can provide original insides to the problem. We developed a new methodology exploiting the frequency selective coherence of the wave field at dense seismic arrays and local antennas that leads to stable and reliable detection, blind source separation, and location of distributed non-stationary sources. The methodology consist of: (1) a signal processing scheme yielding a simplified representation of a seismic signal by an adaptive time-frequency characterization of its statistical properties; (2) a fully probabilistic detection and location algorithm based on back projection of stacked local cross-correlations of the simplified signals. This new approach has been developed and tested on the Shikoku region in Japan, which is an exceptional field laboratory, due to its high seismic activity comprising a wide variety of phenomena observed by the dense Hi-net seismic network operated by NIED. We evaluate the capability and potential of the proposed methodology to detect, locate and characterize the energy release associated to possibly overlapping seismic radiation from earthquakes and low-frequency tectonic tremors. As future direction we also discuss an application to the International Maule Aftershock Deployment (IMAD) in Chile.

  17. An array method for detection, location and characterization of multi-scale seismic energy release associated to the deformation processes of active subduction zones

    NASA Astrophysics Data System (ADS)

    Poiata, N.; Satriano, C.; Bernard, P.; Vilotte, J.; Obara, K.

    2011-12-01

    Detection, location and characterization of the seismic energy release associated to deformation processes in active subduction zones are fundamental for understanding the dynamics of active deformation and the mechanisms of generation and rupturing of large subduction earthquakes. The statistical analysis of this seismic energy release, spanning a wide range of space and time scales, as well as phenomena, (e.g., earthquakes, seismic repeaters, low and very low-frequency earthquakes, tectonic tremors) can provide original insides to the problem. We developed a new methodology exploiting the frequency selective coherence of the wave field at dense seismic arrays and local antennas that leads to stable and reliable detection, blind source separation, and location of distributed non-stationary sources. The methodology consist of: (1) a signal processing scheme yielding a simplified representation of a seismic signal by an adaptive time-frequency characterization of its statistical properties; (2) a fully probabilistic detection and location algorithm based on back projection of stacked local cross-correlations of the simplified signals. This new approach has been developed and tested on the Shikoku region in Japan, which is an exceptional field laboratory, due to its high seismic activity comprising a wide variety of phenomena observed by the dense Hi-net seismic network operated by NIED. We evaluate the capability and potential of the proposed methodology to detect, locate and characterize the energy release associated to possibly overlapping seismic radiation from earthquakes and low-frequency tectonic tremors. As future direction we also discuss an application to the International Maule Aftershock Deployment (IMAD) in Chile.

  18. Late Cenozoic deformation of the Da'an-Dedu Fault Zone and its implications for the earthquake activities in the Songliao basin, NE China

    NASA Astrophysics Data System (ADS)

    Zhongyuan, Yu; Peizhen, Zhang; Wei, Min; Qinghai, Wei; Limei, Wang; Bin, Zhao; Shuang, Liu; Jian, Kang

    2015-08-01

    The Da'an-Dedu Fault Zone is a major tectonic feature cutting through the Songliao Basin from south to north in NE China. Five earthquakes with magnitudes over 5 that occurred during the past 30 years suggest the fault zone is a seismogenic structure with future seismic potential. The structural pattern, tectonic history, Quaternary activity and seismic potential have previously been unknown due to the Quaternary sedimentary coverage and lack of large historic earthquakes (M > 7). In this paper, we use seismic reflection profiles and drilling from petroleum explorations and shallow-depth seismic reflections to study those problems. The total length of the Da'an-Dedu Fault Zone is more than 400 km; modern seismicity delineates it into 4 segments each with a length of 90-100 km. In cross-section view, the folds and associated faults form a complex structural belt with a width of more than 10 km. Shallow-level seismic reflection across the Da'an-Dedu Fault Zone reveals that the Late Quaternary sediments were folded and faulted, indicating its present tectonic activity. The Da'an-Dedu Fault Zone and Songliao Basin have been subjected to three stages of tectonic evolution: a rifting stage characterized by normal faulting and extension (∼145-112 Ma), a prolonged stage of thermal subsidence (∼112-65 Ma), and a tectonic reversal that has been taking place since ∼65 Ma. Our shallow-level reflection profiles show that the folding and reverse faulting have influenced the Late Quaternary sediments. The seismicity and moderate earthquakes suggest that the tectonic activity persists today. The deformation rate across the Da'an-Dedu Fault Zone, however, is measured to be very slow. In conjunction with the inference that most deformation in NE China may be taken up by the Yilan-Yitong Fault Zone bounding the Songliao Basin to the east, we suggest moderate earthquake potential and thus moderate seismic hazards along the Da'an-Dedu Fault Zone. The geological structures, which

  19. Age of the Dawson Arkose, southwestern Air Force Academy, Colorado, and implications for the uplift history of the Front Range

    SciTech Connect

    Kluth, C.F.; Nelson, S.N. )

    1988-01-01

    An angular unconformity within the synorogenic Dawson Arkose (Late Cretaceous-Eocene) is preserved and exposed in areas south of Denver, Colorado, along the eastern side of the Front Range uplift. In the southwestern part of the Air Force Academy, the basal Dawson is concordant with the underlying Laramie and Fox Hills formations and dips 72-84{degree} eastward. Above an intraformational angular unconformity, younger units of the Dawson dip 24{degree}-46{degree} eastward. Smaller angular unconformities (10{degree}{plus minus}), and beds with gradually decreasing dip occur higher in the Dawson section. Rocks above the largest unconformity contain a rich palynomorph assemblage of Late Maestrichtain age. These data indicate that approximately 30{degree}-40{degree}, and possibly as much as approximately 70{degree}, of tilting of the underlying rocks occurred during the Late Maestrichtian (66-70 Ma). It is also possible that approximately 30{degree}-40{degree} of the tilting of the Late Cretaceous rocks occurred between latest Maestrichtian and Eocene (approximately 45 Ma). These results suggest that the transition from a tectonically quiet marine environment to a non-marine, tectonically active condition took place rapidly, probably within a few million years. When combined with published data, the authors study indicates that the Front Range has different tectonic histories on its eastern and its western side, and that the deformation is diachronous along the strike of the eastern side of the Front Range.

  20. The dynamics of oceanic fronts. Part 1: The Gulf Stream

    NASA Technical Reports Server (NTRS)

    Kao, T. W.

    1970-01-01

    The establishment and maintenance of the mean hydrographic properties of large scale density fronts in the upper ocean is considered. The dynamics is studied by posing an initial value problem starting with a near surface discharge of buoyant water with a prescribed density deficit into an ambient stationary fluid of uniform density. The full time dependent diffusion and Navier-Stokes equations for a constant Coriolis parameter are used in this study. Scaling analysis reveals three independent length scales of the problem, namely a radius of deformation or inertial length scale, Lo, a buoyance length scale, ho, and a diffusive length scale, hv. Two basic dimensionless parameters are then formed from these length scales, the thermal (or more precisely, the densimetric) Rossby number, Ro = Lo/ho and the Ekman number, E = hv/ho. The governing equations are then suitably scaled and the resulting normalized equations are shown to depend on E alone for problems of oceanic interest. Under this scaling, the solutions are similar for all Ro. It is also shown that 1/Ro is a measure of the frontal slope. The governing equations are solved numerically and the scaling analysis is confirmed. The solution indicates that an equilibrium state is established. The front can then be rendered stationary by a barotropic current from a larger scale along-front pressure gradient. In that quasisteady state, and for small values of E, the main thermocline and the inclined isopycnics forming the front have evolved, together with the along-front jet. Conservation of potential vorticity is also obtained in the light water pool. The surface jet exhibits anticyclonic shear in the light water pool and cyclonic shear across the front.

  1. Distribution of active faulting along orogenic wedges: Minimum-work models and natural analogue

    NASA Astrophysics Data System (ADS)

    Yagupsky, Daniel L.; Brooks, Benjamin A.; Whipple, Kelin X.; Duncan, Christopher C.; Bevis, Michael

    2014-09-01

    Numerical 2-D models based on the principle of minimum work were used to examine the space-time distribution of active faulting during the evolution of orogenic wedges. A series of models focused on thin-skinned thrusting illustrates the effects of arid conditions (no erosion), unsteady state conditions (accretionary influx greater than erosional efflux) and steady state conditions (accretionary influx balances erosional efflux), on the distribution of fault activity. For arid settings, a general forward accretion sequence prevails, although a significant amount of internal deformation is registered: the resulting fault pattern is a rather uniform spread along the profile. Under fixed erosional efficiency settings, the frontal advance of the wedge-front is inhibited, reaching a steady state after a given forward propagation. Then, the applied shortening is consumed by surface ruptures over a narrow frontal zone. Under a temporal increase in erosional efficiency (i.e., transient non-steady state mass balance conditions), a narrowing of the synthetic wedge results; a rather diffuse fault activity distribution is observed during the deformation front retreat. Once steady balanced conditions are reached, a single long-lived deformation front prevails. Fault activity distribution produced during the deformation front retreat of the latter scenario, compares well with the structural evolution and hinterlandward deformation migration identified in southern Bolivian Subandes (SSA) from late Miocene to present. This analogy supports the notion that the SSA is not in steady state, but is rather responding to an erosional efficiency increase since late Miocene. The results shed light on the impact of different mass balance conditions on the vastly different kinematics found in mountain ranges, suggesting that those affected by growing erosion under a transient unbalanced mass flux condition tend to distribute deformation along both frontal and internal faults, while others

  2. Design of an Ultra-Efficient GaN High Power Amplifier for Radar Front-Ends Using Active Harmonic Load-Pull

    NASA Technical Reports Server (NTRS)

    Thrivikraman, Tushar; Hoffman, James

    2012-01-01

    This work presents a new measurement technique, mixed-signal active harmonic load-pull (MSALP) developed by Anterverta-mw in partnership with Maury Microwave, that allows for wide-band ultra-high efficiency amplifiers to be designed using GaN technology. An overview of the theory behind active load-pull is presented and why load-pull is important for high-power device characterization. In addition, an example procedure is presented that outlines a methodology for amplifier design using this measurement system. Lastly, measured results of a 10W GaN amplifier are presented. This work aims to highlight the benefit of using this sophisticated measurement systems for to optimize amplifier design for real radar waveforms that in turn will simplify implementation of space-based radar systems

  3. Feeding ecology and activity pattern of black-fronted titi monkeys (Callicebus nigrifrons) in a semideciduous tropical forest of southern Brazil.

    PubMed

    Caselli, Christini Barbosa; Setz, Eleonore Zulnara Freire

    2011-10-01

    Most aspects of the ecology and behavior of Callicebus nigrifrons are still unknown. The information available about this species is mainly based on a few studies that also focused on other Callicebus. We examined the feeding behavior and activity pattern of a free-ranging pair of C. nigrifrons between March and November 2007 in an area of semideciduous tropical forest of southeastern Brazil. The study site is located at the southern limit of the Tropical Zone and is characterized by pronounced seasonality. As observed for other Callicebus monkeys, fruits were the most consumed food resource, accounting for 53% of the diet, which was complemented mainly by leaves (16%) but also by invertebrates and flowers (10% of each). A great variety of plant families (28) and species (62) were included in the diet. The titis spent 35% of their time feeding, distributing the remaining time between resting (30%) and traveling (24%). Data presented here indicate that C. nigrifrons prefer high-quality food items (fruit pulp), adding low-quality food items (such as leaves) as the availability of the higher-quality foods decreases. The amount of time spent traveling and resting did not change between seasons, but the time invested in feeding increased during the lean period. The activity pattern was not related to fruit availability, but in months with lower temperatures, monkeys spent more time feeding. We suggest that the feeding ecology and activity pattern of C. nigrifrons reflect adaptations related to annual fluctuations in food availability and temperature, respectively.

  4. Lagrangian fronts in the ocean

    NASA Astrophysics Data System (ADS)

    Prants, S. V.; Budyansky, M. V.; Uleysky, M. Yu.

    2014-05-01

    We introduce the concept of Lagrangian fronts (LFs) in the ocean and describe their importance for analyzing water mixing and transport and the specific features and differences from hydrological fronts. A method of calculating LFs in a given velocity field is proposed. Based on altimeter velocity fields from AVISO data in the northwestern Pacific, we calculate the Lagrangian synoptic maps and identify LFs of different spatial and temporal scales. Using statistical analysis of saury catches in different years according to the Goskomrybolovstvo (State Fisheries Committee of the Russian Federation), we show that LFs can serve as good indicators of places that are favorable for fishing.

  5. Front tracking for gas dynamics

    SciTech Connect

    Chern, I.L.; Glimm, J.; McBryan, O.; Plohr, B.; Yaniv, S.

    1984-05-01

    Front tracking is an adaptive computational method in which a lower dimensional moving grid is fitted to and follows the dynamical evolution of distinguished waves in a fluid flow. The method takes advantage of known analytic solutions, derived from the Rankine-Hugoniot relations, for idealized discontinuities. In this paper the method is applied to the Euler equations describing compressible gas dynamics. The main thrust here is validation of the front tracking method: we present results on a series of test problems for which comparison answers can be obtained by independent methods.

  6. Front tracking for gas dynamics

    SciTech Connect

    Chern, I.; Glimm, J.; McBryan, O.; Plohr, B.; Yaniv, S.

    1986-01-01

    Front tracking is an adaptive computational method in which a lower dimensional moving grid is fitted to and follows the dynamical evolution of distinguished waves in a fluid flow. The method takes advantage of known analytic solutions, derived from the Rankine-Hugoniot relations, for idealized discontinuities. In this paper the method is applied to the Euler equations describing compressible gas dynamics. The main thrust here is validation of the front tracking method: we present results on a series of test problems for which comparison answers can be obtained by independent methods.

  7. Propagating substorm injection fronts

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Arnoldy, R. L.; Feynman, J.; Hardy, D. A.

    1981-01-01

    It is argued that a series of two-satellite observations leads to a clarification of substorm plasma injection, in which boundary motion plays a major role. Emphasis is put on a type of event characterized by abrupt, dispersionless changes in electron intensity and a coincident perturbation that consists of both a field magnitude increase and a small rotation toward more dipolar orientation. Comparing plasma observations at two points, it is found that in active, preinjection conditions the two most important features of the plasma sheet are: (1) the low-energy convection boundary for near-zero energy particles, determined by the magnitude of the large-scale convection electric field; and (2) the precipitation-flow boundary layer between the hot plasma sheet and the atmospherically contaminated inner plasma sheet.

  8. Active Fault Deformation Along the South Boundary of the Western Transverse Ranges Province, Point Dume to the Northern Channel Islands, Southern California

    NASA Astrophysics Data System (ADS)

    Fisher, M. A.; Langenheim, V. E.; Sorlien, C. C.; Nicholson, C.; Sliter, R. W.

    2005-12-01

    The regional fault system forming the south boundary of the Western Transverse Ranges Province (WTRP) extends for about 200 km, from near the city of Los Angeles westward along the south flank of the Santa Monica Mountains and through the northern Channel Islands. Multichannel seismic-reflection data show that fault strands within the province-bounding system are active, and some have dip-slip displacements measured in kilometers. The left-oblique Dume fault is active and shows large displacement as far west as Sycamore knoll, but farther west, the fault tip and a superjacent fold are deeply buried. Thus during future earthquakes, the structural transition near the knoll could represent a boundary between earthquake-rupture segments. The east-west province-bounding fault system strikes at a high angle across and terminates the northwest-trending faults, basins and ridges of the California Continental Borderland. Borderland structures considered here form the western limit of intense middle Miocene oblique extension that accompanied rotation of the WTRP. The transition between extended and intact crust lies along the northwest-trending Santa Cruz-Catalina and Santa Rosa-Cortes Ridges. After the Miocene rotation, structures within these ridges became involved in regional transpression, such that northwestward along the Santa Cruz-Catalina Ridge, thrust faulting becomes increasingly more intense, and adjacent to the province boundary, thrust-faulted rocks completely override Miocene extensional structures. In contrast, rocks making up the Santa Rosa-Cortez Ridge are little deformed. The difference in deformation of the two ridges could result from a combination of: 1) eastward crustal thinning and consequent weakening that developed during the Miocene extension; 2) a difference in horizontal strain across the right-slip San Clemente fault near its termination at the WTRP boundary; 3) strain partitioning along this boundary; and 4) a contrast in bulk rheological

  9. The Mw4.8 Norris Geyser Basin Earthquake of 30 March, 2014 and its Relationship to Crustal Deformation and Seismic Activity of the Yellowstone Volcanic System

    NASA Astrophysics Data System (ADS)

    Farrell, J.; Shelly, D. R.; Smith, R. B.; Puskas, C. M.; Chang, W. L.

    2014-12-01

    The largest earthquake to be recorded in Yellowstone in over 30 years, a magnitude 4.8 earthquake, occurred on March 30, 2014 near the Norris Geyser Basin on the NW side of the 0.64 Ma Yellowstone caldera. The earthquake was felt throughout Yellowstone and the surrounding region. We analyze this unusual event using data from the Yellowstone Seismic and Geodetic networks in the context of active volcanic-tectonic processes of the Yellowstone volcanic system and its relationship to regional swarm seismicity and crustal deformation. Moment tensor analysis of the March 30 earthquake revealed a strike-slip, double-couple source mechanism with no isotropic contribution. This earthquake was part of a larger sequence of earthquake swarm activity in the Norris Geyser Basin area that began in September 2013 and continued into June 2014. During that period, 50-60% of the total seismicity recorded in Yellowstone, including nearly all of the swarm seismicity (earthquakes clustered in time and space), occurred in the Norris Geyser Basin area. In addition, GPS derived deformation data revealed unusually high uplift rates at ~15 cm/yr in the Norris area prior to the MW4.8 event, while a dramatic reversal to subsidence at rates of ~20 cm/yr occurred after the event. Regionally, the much larger Yellowstone caldera had experienced subsidence since January 2010 at rates of ~1.5 cm/yr prior to the MW4.8 event. After March 30, 2014 the caldera reversed to regional uplift at rates of ~10 cm/yr, similar to accelerated uplift rates observed in mid-2004.

  10. Nanomechanical properties of facial sutures and sutural mineralization front.

    PubMed

    Radhakrishnan, P; Mao, J J

    2004-06-01

    The mechanical properties of craniofacial sutures have rarely been investigated. Three facial sutures-the pre-maxillomaxillary (PMS), the nasofrontal (NFS), and the zygomaticotemporal (ZTS)-and their corresponding sutural mineralization fronts in 8 young New Zealand White rabbits were subjected to nano-indentation with atomic force microscopy as a test of the hypothesis that they have different mechanical properties. The average elastic modulus of the PMS was 1.46 +/- 0.24 MPa (mean +/- SD), significantly higher than both the ZTS (1.20 +/- 0.20) and NFS (1.16 +/- 0.18). The average elastic moduli of sutural mineralization fronts 30 micro m away were significantly higher than their corresponding sutures and had the same distribution pattern: the PMS (2.07 +/- 0.24 MPa) significantly higher than both the ZTS (1.56 +/- 0.29) and NFS (1.71 +/- 0.22). Analysis of these data suggests that facial sutures and their immediately adjacent sutural mineralization fronts have different capacities for mechanical deformation. The elastic properties of sutures and sutural mineralization fronts are potentially useful for improving our understanding of their roles in development.

  11. [Front Block distraction].

    PubMed

    Esnault, Olivier

    2015-03-01

    The contribution of the segmental osteotomies in the ortho-surgical protocols is no longer to demonstrate and found a new lease of life thanks to the combination with the bone distraction techniques. The osteotomy of Köle, initially described to close infraclusies, and then used to level very marked curves of Spee has more recently been used to correct anterior crowding. This support is therefore aimed at patients with an incisor and canine Class 2 but molar Class 1 with an isolated mandibular footprint. With minimal orthodontic preparation we can create in two weeks bilateral diastemas that will then be used to align the incisivocanin crowding without stripping or bicuspid extractions. Dental orthodontic movements can be resumed one month after the end of the distraction. This technique is therefore likely to avoid bicuspid extraction and replace some sagittal osteotomy advancement by correction of the overjet. It also helps to correct a incisors labial or lingual tipping playing on differential activation of the cylinders and the distractor. This segmental surgery can be combined with Le Fort 1 surgeries with correction of the transverse and associated meanings, but in a second time, to a mandibular advancement and/or a genioplasty. PMID:25888045

  12. Compliant deformable mirror approach for wavefront improvement

    NASA Astrophysics Data System (ADS)

    Clark, James H.; Penado, F. Ernesto

    2016-04-01

    We describe a compliant static deformable mirror approach to reduce the wavefront concavity at the Navy Precision Optical Interferometer (NPOI). A single actuator pressing on the back surface of just one of the relay mirrors deforms the front surface in a correcting convex shape. Our design uses the mechanical advantage gained from a force actuator sandwiched between a rear flexure plate and the back surface of the mirror. We superimpose wavefront contour measurements with our finite element deformed mirror model. An example analysis showed improvement from 210-nm concave-concave wavefront to 51-nm concave-concave wavefront. With our present model, a 100-nm actuator increment displaces the mirror surface by 1.1 nm. We describe the need for wavefront improvement that arises from the NPOI reconfigurable array, offer a practical design approach, and analyze the support structure and compliant deformable mirror using the finite element method. We conclude that a 20.3-cm-diameter, 1.9-cm-thick Zerodur® mirror shows that it is possible to deform the reflective surface and cancel out three-fourths of the wavefront deformation without overstressing the material.

  13. Active deformation in the Zagros-Makran transition zone inferred from GPS measurements in the interval 2000-2002

    NASA Astrophysics Data System (ADS)

    Bayer, R.; Shabanian, E.; Regard, V.; Doerflinger, E.; Abbassi, M.; Chery, J.; Nilforoushan, F.; Tatar, M.; Vernant, Ph.; Bellier, O.

    2003-04-01

    The actual N-S convergence between the Arabian and the Eurasian plates is partly accommodated in Iran along the Zagros fold and thrust belt with a shortening of 8 mm/yr in the central part (Vernant et al., 2003). To the east of the Musandam peninsula and the strait of Hormuz, the convergence is associated with the subduction of the Oman oceanic lithosphere beneath the Makran with a rate of 18 mm/yr (Vernant et al., 2003). The Bandar Abbas-Strait of Hormuz zone is considered as a transition between the Zagros continental collision and the Makran oceanic subduction. The strain is mainly accommodated along the NNW-SSE trending reverse right lateral Minab-Zendan-Palami faults and along the N-S trending faults of Sarduiyeh, Jiroft and Sabzevaran, south-west of the Lut block (Regard et al ; ? 200). In this study, we used GPS network monitoring to better understand how the current strain regime is distributed from the Zagros continental collision to the Makran oceanic subduction. A regional GPS network was set up and measured in 2000 and 2002 in order to quantify the velocity and the strain-rate field. The data were processed using GAMIT/GLOBK software. Velocities obtained from other GPS measurements (Iran Global Network (Vernant et al., 2003) were added to densify the the velocity field. We conclude that the deformation in the collision/subduction transition zone is accommodated within a transpressional regime along the Minab-Zendan-Palami faults system. The rate of convergence in the Eastern Zagros belt is <8mm/yr. With respect to the stable Musandam peninsula, the horizontal residual velocities of the coastal sites in Zagros are less than 3 mm/yr, evidencing for a weak convergence component below the Persian Gulf. West of the Minab-Zendan-Palami faults, from the coast to the Main Zagros thrust, the N-S shortening within the Zagros belt is associated with rates <5 mm/yr. The GPS results evidence for a N-S global reverse right lateral motion at rate of 10 mm/yr along the

  14. Advanced RF Front End Technology

    NASA Technical Reports Server (NTRS)

    Herman, M. I.; Valas, S.; Katehi, L. P. B.

    2001-01-01

    The ability to achieve low-mass low-cost micro/nanospacecraft for Deep Space exploration requires extensive miniaturization of all subsystems. The front end of the Telecommunication subsystem is an area in which major mass (factor of 10) and volume (factor of 100) reduction can be achieved via the development of new silicon based micromachined technology and devices. Major components that make up the front end include single-pole and double-throw switches, diplexer, and solid state power amplifier. JPL's Center For Space Microsystems - System On A Chip (SOAC) Program has addressed the challenges of front end miniaturization (switches and diplexers). Our objectives were to develop the main components that comprise a communication front end and enable integration in a single module that we refer to as a 'cube'. In this paper we will provide the latest status of our Microelectromechanical System (MEMS) switches and surface micromachined filter development. Based on the significant progress achieved we can begin to provide guidelines of the proper system insertion for these emerging technologies. Additional information is contained in the original extended abstract.

  15. Align the Front End First.

    ERIC Educational Resources Information Center

    Perry, Jim

    1995-01-01

    Discussion of management styles and front-end analysis focuses on a review of Douglas McGregor's theories. Topics include Theories X, Y, and Z; leadership skills; motivational needs of employees; intrinsic and extrinsic rewards; and faulty implementation of instructional systems design processes. (LRW)

  16. Front instability in stratified media

    NASA Astrophysics Data System (ADS)

    Beltrame, Philippe

    2013-04-01

    Preferential flow in unsaturated soil may due to local heterogeneities like worm burrows but also to front instability leading to unstable finger flow (fingered pattern) in sandy textured soils. This last spontaneous preferential flow cannot be described by the standard Richards equation. Cueto-Felgueroso and Juanes proposed recently a phase field model in order to take into account a macroscopic surface tension effect at the front [1]. Their model simulates successfully the interface instability of an advancing front. We aim at simulating and understanding front instability passing a textural soil discontinuity for which the finger flow is particularly visible. We consider sand layers with different characteristics such as granulometry. Moreover, the wettability is taken into account by adding a hydrophobic term in the free energy of the phase field model. The hydrophobicity part is not only relevant for repellent soil but also to model the ultra-thin films [2]. Therefore, in our framework, this may have an influence at the front because the water saturation is nearly zero. Such a wettability influence on infiltration in porous media has recently been measured in [3]. The governing equation is analogous to the lubrication equation for which we pointed out the specific numerical difficulties [4]. A numerical code to perform time integration and bifurcation analysis was developed in [4] allowing to determine the onset of instability and its resulting dynamics in the parameter space [5]. We compute the parameter range for which the front stops when reaching the layers interface. As in [4], there is two main mechanisms that allow water to cross over the discontinuity. A first mechanism, called «depinning», leads to an intermittent flow and the second one, to a front instability and then to a finger flow. There is a parameter domain where both instabilities are present leading to a complex spatio-temporal dynamics. Finally, it is noteworthy that the wettability

  17. Oscillations and uniaxial mechanochemical waves in a model of an active poroelastic medium: Application to deformation patterns in protoplasmic droplets of Physarum polycephalum

    NASA Astrophysics Data System (ADS)

    Alonso, Sergio; Strachauer, Ulrike; Radszuweit, Markus; Bär, Markus; Hauser, Marcus J. B.

    2016-04-01

    Self-organization in cells often manifests itself in oscillations and waves. Here, we address deformation waves in protoplasmic droplets of the plasmodial slime mould Physarum polycephalum by modelling and experiments. In particular, we extend a one-dimensional model that considered the cell as a poroelastic medium, where active tension caused mechanochemical waves that were regulated by an inhibitor (Radszuweit et al., 2013). Our extension consists of a simple, qualitative chemical reaction-diffusion model (Brusselator) that describes the regulation of the inhibitor by another biochemical species. The biochemical reaction enhances the formation of mechanochemical waves if the reaction rates and input concentrations are near or inside an oscillatory regime. The period of the waves is found to be controlled by the characteristic oscillation period, whereas their wavelength is set by mechanical parameters. The model also allows for a systematic study of the chemical activity at the onset of mechanochemical waves. We also present examples for pattern formation in protoplasmic droplets of Physarum polycephalum including global oscillations where the central region of the droplets is in antiphase to the boundary zone, as well as travelling and standing wave-like uniaxial patterns. Finally, we apply our model to reproduce these experimental results by identifying the active tension inhibitor with the intracellular calcium concentration in the Physarum droplets and by using parameter values from mechanical experiments, respectively knowledge about the properties of calcium oscillations in Physarum. The simulation results are then found to be in good agreement with the experimental observations.

  18. Active upper crust deformation pattern along the southern edge of the Tyrrhenian subduction zone (NE Sicily): Insights from a multidisciplinary approach

    NASA Astrophysics Data System (ADS)

    Palano, Mimmo; Schiavone, Domenico; Loddo, Mariano; Neri, Marco; Presti, Debora; Quarto, Ruggiero; Totaro, Cristina; Neri, Giancarlo

    2015-08-01

    Using a multidisciplinary dataset based on gravimetric, seismic, geodetic and geological observations, we provide an improved picture of the shallow structure and dynamics of the southern edge of the Tyrrhenian subduction zone. With a local earthquake tomography we clearly identify two main crustal domains in the upper 15 km characterized by different P-wave velocity values: a high-velocity domain comprising southeasternmost Tyrrhenian Sea, NE Sicily and Messina Straits, and a low-velocity domain comprising Mt. Etna and eastern Sicily. The transition between the two domains shows a good spatial correspondence with a wider set of faults including the Taormina Fault System (TFS) and the Aeolian-Tindari-Letojanni Fault System (ATLFS), two nearly SE-striking fault systems crossing northeastern Sicily and ending on the Ionian shoreline of Sicily according to many investigators. Within this set of faults, most of the deformation/seismicity occurs along the northern and central segments of ATLFS, compared to low activity along TFS. A lack of seismicity (both recent and historical) is observed in the southern sector of ATLFS where, however, geodetic data reveal significant deformation. Our multidisciplinary dataset including offshore observations suggests the southeastward continuation of the ATLFS into the Ionian Sea until joining with the faults cutting the Ionian accretionary wedge described in the recent literature. Our findings imply the existence of a highly segmented crustal shear zone extending from the Aeolian Islands to the Ionian Abyssal plain, that we believe plays the role of accommodating differential motion between the Southern Tyrrhenian unit and the western compressional domain of Sicily. The ATLFS, which is a main part of the inferred shear zone, behaves similarly to what often observed at the edges of retreating subduction slabs, where the overriding plate drifts with a highly non-uniform transform motion along the lateral borders.

  19. Mechanism of activation of TiFe intermetallics for hydrogen storage by severe plastic deformation using high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Edalati, Kaveh; Matsuda, Junko; Arita, Makoto; Daio, Takeshi; Akiba, Etsuo; Horita, Zenji

    2013-09-01

    TiFe, a potential candidate for solid-state hydrogen storage, does not absorb hydrogen without a sophisticated activation process because of severe oxidation. This study shows that nanostructured TiFe becomes active by high-pressure torsion (HPT) and is not deactivated even after storage for several hundred days in the air. Surface segregation and formation of Fe-rich islands and cracks occur after HPT. The Fe-rich islands are suggested to act as catalysts for hydrogen dissociation and cracks and nanograin boundaries act as pathways to transport hydrogen through the oxide layer. Rapid atomic diffusion by HPT is responsible for enhanced surface segregation and hydrogen transportation.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Kjøll, H. J.; Viola, G.; Menegon, L.; Sørensen, B. E.

    2015-01-01

    A coarse grained, statically crystallized quartz vein, embedded in a phyllonitic matrix, was studied by EBSD and optical microscopy to gain insights into the processes of strain localization in quartz deformed under low-grade conditions, broadly coincident with the frictional-viscous transition. The vein is from a high strain zone at the front of the Porsa Imbricate Stack in the Paleoproterozoic Repparfjord Tectonic Window in northern Norway. The vein was deformed under lower greenschist facies conditions during deformation along a large out-of-sequence phyllonitic thrust of Caledonian age. The host phyllonite formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation was initially accommodated by basal ⟨a⟩ slip of quartz during the development of a mesoscopic pervasive extensional crenulation cleavage. Under the prevailing boundary conditions, however, dislocation glide-accommodated deformation of quartz resulted inefficient and led to dislocation tangling and strain hardening of the vein. In response to hardening, to the progressive increase of fluid pressure and the increasing competence contrast between the vein and the weak foliated host phyllonite, quartz crystals began to deform frictionally along specific, optimally oriented lattice planes, creating microgouges along microfractures. These were, however, rapidly sealed by nucleation of new grains as transiently over pressured fluids penetrated the deforming system. The new nucleated grains grew initially by solution-precipitation and later by grain boundary migration. Due to the random initial orientation of the vein crystals, strain was accommodated differently in the individual crystals, leading to the development of remarkably different microstructures. Crystals

  2. Regularities of bainitic steel deformation transition

    NASA Astrophysics Data System (ADS)

    Gromov, V. E.; Nikitina, E. N.; Ivanov, Yu F.; Aksenova, K. V.

    2016-09-01

    Quantitative analysis of defect and carbide subsystems evolution in medium-carbon bainitic steel subjected to compressive strain up to 36% was performed by means of transmission electron diffraction microscopy. Dislocation substructure and carbide phase parameters dependence on degree of deformation are identified, possible reasons of staging in their changes are discussed. It is suggested that the reason for bainitic steel softening at high (over 15%) degrees of deformation is activation of deformation microtwinning process.

  3. Reaction front formation in contaminant plumes

    NASA Astrophysics Data System (ADS)

    Cribbin, Laura B.; Winstanley, Henry F.; Mitchell, Sarah L.; Fowler, Andrew C.; Sander, Graham C.

    2014-12-01

    The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front.

  4. In situ TEM straining of nanograined free-standing thin films reveals various unexpected deformation mechanisms.

    SciTech Connect

    Follstaedt, David Martin; Knapp, James Arthur; Clark, Blythe G.; Hattar, Khalid M.; Robertson, Ian M.

    2010-04-01

    In-situ transmission electron microscopy (TEM) straining experiments provide direct detailed observation of the deformation and failure mechanisms active at a length scale relevant to nanomaterials. This presentation will detail continued investigations into the active mechanisms governing high purity nanograined pulsed-laser deposited (PLD) nickel, as well as recent work into dislocation-particle interactions in nanostructured PLD aluminum-alumina alloys. Straining experiments performed on nanograined PLD free-standing nanograined Ni films with an engineered grain size distribution revealed that the addition of ductility with limited decrease in strength, reported in such metals, can be attributed to the simultaneous activity of three deformation mechanisms in front of the crack tip. At the crack tip, a grain agglomeration mechanism occurs where several nanograins appear to rotate, resulting in a very thin, larger grain immediately prior to failure. In the classical plastic zone in front of the crack tip, a multitude of mechanisms were found to operate in the larger grains including: dislocation pile-up, twinning, and stress-assisted grain growth. The region outside of the plastic zone showed signs of elasticity with limited indications of dislocation activity. The insight gained from in-situ TEM straining experiments of nanograined PLD Ni provides feedback for models of the deformation and failure in nanograined FCC metals, and suggests a greater complexity in the active mechanisms. The investigation into the deformation and failure mechanisms of FCC metals via in-situ TEM straining experiments has been expanded to the effect of hard particles on the active mechanisms in nanograined aluminum with alumina particles. The microstructures investigated were developed with varying composition, grain size, and particle distribution via tailoring of the PLD conditions and subsequent annealing. In order to develop microstructures suitable for in-situ deformation testing

  5. Deformation verification and surface improvement of active stressed lap for 4  m-class primary mirror fabrication.

    PubMed

    Zhao, Hongshen; Li, Xiaojin; Fan, Bin; Zeng, Zhige

    2015-04-01

    The surface shape accuracy of the active stressed lap impacts the performance of grinding and polishing in the fabrication of large mirrors. We introduce a model of active stressed lap for the fabrication of a 4 m f/1.5 mirror based on finite element analysis (FEA), and the lap surface accuracy achieves RMS<1.8  μm in the FEA method. Using the lap surface measurement system, experimental verification is put forward, and the RMS of the measured lap surface is within 2 μm in practice. A general improvement in lap surface accuracy using the Zernike polynomial is shown. After compensating the calculation errors, the lap surface accuracy is improved by 8%-23%, and achieves RMS<1.5  μm, which is appropriate for practical grinding and polishing. PMID:25967173

  6. Growth and gravitational collapse of a mountain front of the Eastern Cordillera of Colombia

    NASA Astrophysics Data System (ADS)

    Kammer, Andreas; Montana, Jorge; Piraquive, Alejandro

    2016-04-01

    The Eastern Cordillera of Colombia is bracketed between the moderately east-dipping flank of the Central Cordillera on its western and the gently bent Guayana shield on its eastern side. It evolved as a response to a considerable displacement transfer from the Nazca to the Southamerican plate since the Oligocene break-up of the Farallon plate. One of its distinctive traits refers to its significant shortening by penetrative strain at lower and folding at higher structural levels, approximating a wholesale pure-shear in analogy to a vice model or a crustal welt sandwiched between rigid buttresses. This contrasting behavior may be explained by the spatial coincidence between Neogene mountain belt and a forebulge that shaped the foreland trough during a Cretaceous subduction cycle and was very effective in localizing a weakening of the backarc region comprised between two basin margin faults. In this paper we examine a two-phase evolution of the Eastern mountain front. Up to the late Miocene deformation was restrained by the inherited eastern basin margin fault and as the cordilleran crust extruded, a deformation front with an amplitude similar the present structural relief of up to 10.000 m may have built up. In the Pliocene convergence changed from a roughly strike-perpendicular to an oblique E-W direction and caused N-S trending faults to branch off from the deformation front. This shortening was partly driven by a gravitational collapse of the Miocene deformation front, that became fragmented by normal faults and extruded E on newly formed Pliocene thrust faults. Normal faults display displacements of up to 3000 m and channelized hydrothermal fluids, leading to the formation of widely distributed fault breccias and giving rise to a prolific Emerald mineralization. In terms of wedge dynamics, the Pliocene breaching of the early formed deformation front helped to establish a critical taper.

  7. Weather fronts and acute myocardial infarction

    NASA Astrophysics Data System (ADS)

    Kveton, Vit

    1991-03-01

    Some methodological aspects are discussed of the investigation of acute infarct myocarditis (AIM) in relation to weather fronts. Results of a new method of analysis are given. Data were analysed from about the hour of the onset of symptoms, and led to the diagnosis of AIM either immediately or within a few hours or days (3019 cases observed over 4.5 years during 1982 1986 in Plzen, Czechoslovakia). Weather classification was based on three factors (the type of the foregoing front, the type of the subsequent front, the time section of the time interval demarcated by the passage of the surfaces of the fronts). AIM occurrence increased in particular types of weather fronts: (i) by 30% during 7 12 h after a warm front, if the time span between fronts exceeded 24 h; (ii) by 10% in time at least 36 h distant from the foregoing cold or occlusion front and from the succeeding warm or occlusion front; (iii) by 20% during 0 2 h before the passage of the front, provided the foregoing front was not warm and the interval between fronts exceeded 5 h. AIM occurrence decreased by 15% 20% for time span between fronts > 24 h at times 6 11, 6 23 and 6 35 h before a coming warm or occlusion front (for interfrontal intervals 25 48, 49 72 and possibly > 72 h), and also at 12 23 and possibly 12 35 h before a cold front (for intervals 49 72 and possibly > 72 h), if the foregoing front was cold or an occlusion front.

  8. InSAR analysis of surface deformation over permafrost to estimate active layer thickness based on one-dimensional heat transfer model of soils.

    PubMed

    Li, Zhiwei; Zhao, Rong; Hu, Jun; Wen, Lianxing; Feng, Guangcai; Zhang, Zeyu; Wang, Qijie

    2015-01-01

    This paper presents a novel method to estimate active layer thickness (ALT) over permafrost based on InSAR (Interferometric Synthetic Aperture Radar) observation and the heat transfer model of soils. The time lags between the periodic feature of InSAR-observed surface deformation over permafrost and the meteorologically recorded temperatures are assumed to be the time intervals that the temperature maximum to diffuse from the ground surface downward to the bottom of the active layer. By exploiting the time lags and the one-dimensional heat transfer model of soils, we estimate the ALTs. Using the frozen soil region in southern Qinghai-Tibet Plateau (QTP) as examples, we provided a conceptual demonstration of the estimation of the InSAR pixel-wise ALTs. In the case study, the ALTs are ranging from 1.02 to 3.14 m and with an average of 1.95 m. The results are compatible with those sparse ALT observations/estimations by traditional methods, while with extraordinary high spatial resolution at pixel level (~40 meter). The presented method is simple, and can potentially be used for deriving high-resolution ALTs in other remote areas similar to QTP, where only sparse observations are available now. PMID:26480892

  9. InSAR analysis of surface deformation over permafrost to estimate active layer thickness based on one-dimensional heat transfer model of soils

    PubMed Central

    Li, Zhiwei; Zhao, Rong; Hu, Jun; Wen, Lianxing; Feng, Guangcai; Zhang, Zeyu; Wang, Qijie

    2015-01-01

    This paper presents a novel method to estimate active layer thickness (ALT) over permafrost based on InSAR (Interferometric Synthetic Aperture Radar) observation and the heat transfer model of soils. The time lags between the periodic feature of InSAR-observed surface deformation over permafrost and the meteorologically recorded temperatures are assumed to be the time intervals that the temperature maximum to diffuse from the ground surface downward to the bottom of the active layer. By exploiting the time lags and the one-dimensional heat transfer model of soils, we estimate the ALTs. Using the frozen soil region in southern Qinghai-Tibet Plateau (QTP) as examples, we provided a conceptual demonstration of the estimation of the InSAR pixel-wise ALTs. In the case study, the ALTs are ranging from 1.02 to 3.14 m and with an average of 1.95 m. The results are compatible with those sparse ALT observations/estimations by traditional methods, while with extraordinary high spatial resolution at pixel level (~40 meter). The presented method is simple, and can potentially be used for deriving high-resolution ALTs in other remote areas similar to QTP, where only sparse observations are available now. PMID:26480892

  10. Multi Front-End Engineering

    NASA Astrophysics Data System (ADS)

    Botterweck, Goetz

    Multi Front-End Engineering (MFE) deals with the design of multiple consistent user interfaces (UI) for one application. One of the main challenges is the conflict between commonality (all front-ends access the same application core) and variability (multiple front-ends on different platforms). This can be overcome by extending techniques from model-driven user interface engineering.We present the MANTRA approach, where the common structure of all interfaces of an application is modelled in an abstract UI model (AUI) annotated with temporal constraints on interaction tasks. Based on these constraints we adapt the AUI, e.g., to tailor presentation units and dialogue structures for a particular platform. We use model transformations to derive concrete, platform-specific UI models (CUI) and implementation code. The presented approach generates working prototypes for three platforms (GUI, web, mobile) integrated with an application core via web service protocols. In addition to static evaluation, such prototypes facilitate early functional evaluations by practical use cases.

  11. Geomorphic and paleoseismic evidence for late Quaternary deformation in the southwest Kashmir Valley, India: Out-of-sequence thrusting, or deformation above a structural ramp?

    NASA Astrophysics Data System (ADS)

    Madden, C.; Ahmad, S.; Meigs, A.

    2011-12-01

    In the northwest Himalaya, partitioning of Indian-Eurasian convergence across multiple active structures, including a fold at the deformation front, and the Riasi thrust 60 km to the north, suggests that strain is partially accommodated by out-of-sequence thrusting. Deformation of the Plio-Pleistocene Karawa deposits (KD) and latest Pleistocene fluvial terraces on the southwest side of the Kashmir Valley (KV) indicate that deformation also occurs 100 km north of the deformation front. A historical record of 13 earthquakes in the valley over the last millennium, including damaging earthquakes in 1555 and 1885, further suggests that the KV is a locus of active deformation. We use geomorphic mapping, terrace profiling, paleoseismic trenching, and radiometric dating to constrain the extent, timing, rate and style of deformation in the KV. Tectonic geomorphic mapping on high-resolution satellite imagery reveals a series of discontinuous scarps, which we call the Balapora fault (BF), cutting the KD and younger terraces over 45-60 km south of the Jehlum River. Near the north end of the BF, only the highest three of six strath terraces that cross the fault along the Shaliganaga River are deformed, and optically stimulated luminescence (OSL) ages on the highest undeformed terrace show that the fault has not moved there in 50 +/-3 ka. To the south, a flight of five strath terraces along the Sasara River have been uplifted by the BF. Correlating soil and loess stratigraphy from the youngest deformed terrace dated terraces in nearby drainages suggests that deformation has occurred since ~50 ka. Further south, along the Rembiara River (RR), the BF deforms two regionally extensive terraces. Using an OSL age of 51 +/-11 ka collected from fluvial deposits a few meters above the lower strath, and a measured strath elevation above the river of 19 +/- 1 m at the fault, we calculate an average incision rate of 0.3-0.5 mm/yr. An exposure on the left bank of the RR reveals that the BF

  12. Slow slip and the transition from fast to slow fronts in the rupture of frictional interfaces.

    PubMed

    Trømborg, Jørgen Kjoshagen; Sveinsson, Henrik Andersen; Scheibert, Julien; Thøgersen, Kjetil; Amundsen, David Skålid; Malthe-Sørenssen, Anders

    2014-06-17

    The failure of the population of microjunctions forming the frictional interface between two solids is central to fields ranging from biomechanics to seismology. This failure is mediated by the propagation along the interface of various types of rupture fronts, covering a wide range of velocities. Among them are the so-called slow fronts, which are recently discovered fronts much slower than the materials' sound speeds. Despite intense modeling activity, the mechanisms underlying slow fronts remain elusive. Here, we introduce a multiscale model capable of reproducing both the transition from fast to slow fronts in a single rupture event and the short-time slip dynamics observed in recent experiments. We identify slow slip immediately following the arrest of a fast front as a phenomenon sufficient for the front to propagate further at a much slower pace. Whether slow fronts are actually observed is controlled both by the interfacial stresses and by the width of the local distribution of forces among microjunctions. Our results show that slow fronts are qualitatively different from faster fronts. Because the transition from fast to slow fronts is potentially as generic as slow slip, we anticipate that it might occur in the wide range of systems in which slow slip has been reported, including seismic faults. PMID:24889640

  13. Unimorph-type deformable mirror for cryogenic telescopes

    NASA Astrophysics Data System (ADS)

    Reinlein, Claudia; Goy, Matthias; Lange, Nicolas; Kinast, Jan

    2014-07-01

    Deformable mirrors can be used in cryogenic instruments to compensate for temperature-induced deformations. A unimorph-type deformable mirror consists of a mirror substrate and a piezoelectric layer bonded on substrates rear surface. A challenge in the design of the deformable mirror is the lack of knowledge about material properties. Therefore, we measured the coefficient of thermal expansion (CTE) of the substrate material TiAl6V4 between 295 K and 86 K. The manufactured mirror is characterized by an adaptive optical measurement setup in front of a test cryostat. The measured mirror deformations are feedback into a finite element model to calculate the CTE of the piezoelectric layer. We compare our obtained results to other published CTE-values for the piezoelectric material PIC151.

  14. Thermocapillary motion of deformable drops

    NASA Technical Reports Server (NTRS)

    Haj-Hariri, Hossein; Shi, Qingping; Borhan, Ali

    1994-01-01

    The thermocapillary motion of initially spherical drops/bubbles driven by a constant temperature gradient in an unbounded liquid medium is simulated numerically. Effects of convection of momentum and energy, as well as shape deformations, are addressed. The method used is based on interface tracking on a base cartesian grid, and uses a smeared color or indicator function for the determination of the surface topology. Quad-tree adaptive refinement of the cartesian grid is implemented to enhance the fidelity of the surface tracking. It is shown that convection of energy results in a slowing of the drop, as the isotherms get wrapped around the front of the drop. Shape deformation resulting from inertial effects affect the migration velocity. The physical results obtained are in agreement with the existing literature. Furthermore, remarks are made on the sensitivity of the calculated solutions to the smearing of the fluid properties. Analysis and simulations show that the migration velocity depends very strongly on the smearing of the interfacial force whereas it is rather insensitive to the smearing of other properties, hence the adaptive grid.

  15. Observations of gravity waves at atmospheric fronts

    NASA Astrophysics Data System (ADS)

    Abusamah, Azizan B. Hj

    1990-09-01

    An observational study of pressure perturbations associated with the passage of atmospheric fronts over the British Isles using a triangular array of sensitive microbarographs reveals the preponderance of gravity wave activities in the vicinity of the surface cold front (SCF). Examination of the time series of these pressure perturbations in the frequency domain shows an enhancement for frequencies less than the local buoyancy frequency N after the passage of the SCF. The spectral analysis also shows two predominant frequency peaks usually located near N and N/2 s(exp -1). Isolating these frequencies shows that there is a systematic amplitude modulation with an amplification near the SCF and at a region 2-3 hours before and after the SCF passage. The cross-correlation analysis reveals that the gravity waves in the post SCF region propagate towards the SCF. As these waves approach the SCF, the across front component of the phase speed decreases and the direction of propagation of the wave rotates in an anticlockwise manner. It is found that a consistent description of the gravity waves can only be made if first the waves are assumed to be ducted, i.e. there is a reflecting layer aloft, and second that as these waves propagate through the frontal environment, due to the inhomogeneity, they are refracted. A number of conceptual models are then developed to account for the observed wave behavior in a frontal region. In this investigation it is shown that the stable layer associated with the frontal zone can form a good upper reflector for non-hydrostatic gravity waves. It is also argued that the slope of this layer plays an important role in the refraction of the observed gravity waves. A model of wave propagation in a wedge is then used to account for this slope.

  16. Active faulting and deformation of the Coalinga anticline as interpreted from three-dimensional velocity structure and seismicity

    USGS Publications Warehouse

    Eberhart-Phillips, D.

    1989-01-01

    This work gives a clear picture of the geometry of aftershock seismicity in a large thrust earthquake. Interpretation of hypocenters and fault plane solutions, from the 1983 Coalinga, Coast Range California, earthquake sequence, in combination with the three-dimensional velocity structure shows that the active faulting beneath the fold primarily consists of a set of southwest dipping thrusts uplifting blocks of higher-velocity material. With the three-dimensional velocity model each individual hypocenter moved slightly (0-2km) in accord with the details of the surrounding velocity structure, so that secondary features in the seismicity pattern are more detailed than with a local one-dimensional model and station corrections. The overall character of the fault plane solutions was not altered by the three-dimensional model, but the more accurate ray paths did result in distinct changes. In particular, the mainshock has a fault plane dipping 30?? southwest instead of the 23?? obtained with the one-dimensional model. -from Author

  17. Deformation of redox-active polymer gel based on polysiloxane backbone and bis(benzodithiolyl)bithienyl scaffold.

    PubMed

    Ohtake, Toshihiro; Tanaka, Hideki; Matsumoto, Tetsuro; Ohta, Akira; Kimura, Mutsumi

    2014-12-01

    Redox-active polymer gels consisting of polysiloxane backbone and bis(benzodithiolyl)bithienyl units have been designed and synthesized. The bis(benzodithiolyl)bithienyl units, which undergo interconversion between cyclic form and opened dicationic form, have been incorporated into polysiloxane backbone via hydrosilylation of vinyl-terminated bis(benzodithiolyl)bithienyl derivative and poly(methylhydrosiloxane) (PMHS) or poly(dimethylsiloxane-co-hydrogenmethylsiloxane) (PDMS-co-PMHS), resulting in polymer gels cross-linked with bis(benzodithiolyl)bithienyl units. After the incorporation of M1 into polysiloxane backbone, these polymer gels (P1 and P2) also exhibit redox responses associated with the electrochemical interconversion of the bis(benzodithiolyl)bithienyl moieties. The polymer gels show swelling behavior upon chemical oxidization, and bending behavior has been observed for the polymer gel immobilized poly(vinylidene difluoride) (PVdF) film. These results provide a useful perspective for fabricating redox-triggered polymer gel actuators based on the conformational change of the functional molecular unit. PMID:25400032

  18. Dynamic Strain Aging and Oxidation Effects on the Thermomechanical Fatigue Deformation of Reduced Activation Ferritic-Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Nagesha, A.; Kannan, R.; Srinivasan, V. S.; Sandhya, R.; Choudhary, B. K.; Laha, K.

    2016-03-01

    Thermomechanical fatigue (TMF) behavior of a reduced activation ferritic-martensitic steel was investigated under in-phase (IP) and out-of-phase (OP) conditions under different mechanical strain amplitudes and temperature regimes. OP TMF was generally observed to result in the lowest cyclic lives compared to both IP TMF and isothermal low cycle fatigue (IF) at the maximum temperature ( T max). The stress-strain hysteresis loops under TMF were marked by extensive serrations associated with dynamic strain aging (DSA) at the strain amplitudes of ±0.4 and ±0.6 pct. The serrations were noticed during the downward ramp of temperature that resulted in IP and OP TMF exhibiting jerky flow in the compressive and tensile portions, respectively. However, no evidence of serrated flow was seen under IF cycling at any of the temperatures within the TMF cycle. The stress response during IP TMF was marked by a near-saturation regime over 65 to 70 pct of life in contrast to continuous cyclic softening in the case of OP TMF. The marked life reduction observed under OP cycling at the strain amplitudes of ±0.4 and ±0.6 pct was attributed to the deleterious influence associated with oxidation, DSA, and tensile mean stress. The findings assume importance in the context of elevated temperature fatigue design, considering the fact that the IF data at T max are deemed adequately conservative in traditional design approaches.

  19. Late Quaternary Deformation along the North Wuitaishan Fault of the Shanxi Graben System: Active Intracontinental Rifting in North China

    NASA Astrophysics Data System (ADS)

    Corley, J.; Cochran, W. J.; Hinrichs, N.; Ding, R.; Zhang, S.; Gomez, F.

    2012-12-01

    The Shanxi rift system in north China is an intracontinental rift zone which has been active since the late Tertiary. and has produced many destructive earthquakes in recorded history. This area is of particular interest for earthquake research because of the high seismicity levels in an intraplate setting. The Shanxi rift system is composed of NNE-oriented en-echelon half-graben basins controlled by normal faults. This study focuses on the north Wutaishan fault, which bounds the Wutai Mountains and the Xingding basin, located in the northern part of the Shanxi rift system. Quaternary tectonism is investigated using remotely-sensed imagery for mapping of large tectonically-influenced landforms, field investigations for ground truth, and structural analyses. Initial neotectonic mapping utilized stereoscopic Corona satellite imagery to differentiate between fluvial and agricultural terraces; Cartosat-based DEMs were used to correct altitude measurements of terrace heights and to analyze streams and other landforms for morphometric analysis. Fluvial terraces are used to reconstruct paleo-stream profiles of the Yangyan River and nearby tributaries to determine mountain uplift rates inferred from fluvial incision, basin extension rates, and possible warping of the footwall basin block. Field work provided ground truth for fluvial terrace altitude, type of terrace, and thicknesses of alluvial and loess deposits. Another aspect of the study involves development of structural cross-section to relate fault slip to regional tectonic strain. Fault kinematic analysis of micro-fault features found in bedrock were used to assess the Quaternary stress field. Results of this study have implications in the understanding of earthquake recurrence intervals and basin evolution in the Shanxi rift system and more generally, can improve the understanding of spatial and temporal variations of seismic events in intraplate settings.

  20. Active tectonic morphology and submarine deformation of the northern Gulf of Eilat/Aqaba from analyses of multibeam data

    NASA Astrophysics Data System (ADS)

    Tibor, Gideon; Niemi, Tina M.; Ben-Avraham, Zvi; Al-Zoubi, Abdallah; Sade, Ronnie A.; Hall, John K.; Hartman, Gal; Akawi, Emad; Abueladas, Abdelrahmem; Al-Ruzouq, Rami

    2010-12-01

    A high-resolution marine geophysical study was conducted during October-November 2006 in the northern Gulf of Aqaba/Eilat, providing the first multibeam imaging of the seafloor across the entire gulf head spanning both Israeli and Jordanian territorial waters. Analyses of the seafloor morphology show that the gulf head can be subdivided into the Eilat and Aqaba subbasins separated by the north-south-trending Ayla high. The Aqaba submarine basin appears starved of sediment supply, apparently causing erosion and a landward retreat of the shelf edge. Along the eastern border of this subbasin, the shelf is largely absent and its margin is influenced by the Aqaba Fault zone that forms a steep slope partially covered by sedimentary fan deltas from the adjacent ephemeral drainages. The Eilat subbasin, west of the Ayla high, receives a large amount of sediment derived from the extensive drainage basins of the Arava Valley (Wadi ’Arabah) and Yutim River to the north-northeast. These sediments and those entering from canyons on the south-western border of this subbasin are transported to the deep basin by turbidity currents and gravity slides, forming the Arava submarine fan. Large detached blocks and collapsed walls of submarine canyons and the western gulf margin indicate that mass wasting may be triggered by seismic activity. Seafloor lineaments defined by slope gradient analyses suggest that the Eilat Canyon and the boundaries of the Ayla high align along north- to northwest-striking fault systems—the Evrona Fault zone to the west and the Ayla Fault zone to the east. The shelf-slope break that lies along the 100 m isobath in the Eilat subbasin, and shallower (70-80 m isobaths) in the Aqaba subbasin, is offset by approx. 150 m along the eastern edge of the Ayla high. This offset might be the result of horizontal and vertical movements along what we call the Ayla Fault on the east side of the structure. Remnants of two marine terraces at 100 m and approx. 150 m water

  1. Active tectonic morphology and submarine deformation of the northern Gulf of Eilat/Aqaba from analyses of multibeam data

    NASA Astrophysics Data System (ADS)

    Tibor, Gideon; Niemi, Tina; Ben-Avraham, Zvi; Al-Zoubi, Abdallah; Sade, Ronnie; Hall, John; Hartman, Gal; Akawi, Emad; Abueladas, Abed; Al-Ruzouq, Rami

    2010-05-01

    A high-resolution marine geophysical study was conducted during October-November 2006 in the northern Gulf of Aqaba/Eilat (gulf head). The gulf head can be subdivided into the Eilat and Aqaba subbasins separated by the north-south-trending Ayla high. The Aqaba submarine basin appears starved of sediment supply, apparently causing erosion and a landward retreat of the shelf edge. Along the eastern border of this subbasin, the shelf is largely absent and its margin is influenced by the Aqaba fault zone that forms a steep slope partially covered by sedimentary fan deltas from the adjacent ephemeral drainages. The Eilat subbasin, west of the Ayla high, receives a large amount of sediment derived from the extensive drainage basins of the Arava Valley (Wadi 'Arabah) and Yutim River to the north-northeast. These sediments and those entering from canyons on the south-western border of this subbasin are transported to the deep basin by turbidity currents and gravity slides, forming the Arava submarine fan. Large detached blocks and collapsed walls of submarine canyons and the western gulf margin indicate that mass wasting may be triggered by seismic activity. Seafloor lineaments defined by slope gradient analyses suggest that the Eilat Canyon and the boundaries of the Ayla high align along north- to northwest-striking fault systems—the Evrona Fault Zone to the west and the Ayla Fault Zone to the east. The shelf-slope break that lies along the 100 m isobath in the Eilat subbasin, and shallower (70-80 m isobaths) in the Aqaba subbasin, is offset by approx. 150 m along the eastern edge of the Ayla high. This offset might be the result of horizontal and vertical movements along what we call the Ayla Fault on the east side of the structure. Remnants of two marine terraces at 100 m and approx. 150 m water depths line the southwest margin of the gulf. These terraces are truncated by faulting along their northern end. Fossil coral reefs, which have a similar

  2. Stability of a directional solidification front in subdiffusive media.

    PubMed

    Hamed, Mohammad Abu; Nepomnyashchy, Alexander A

    2014-01-01

    The efficiency of crystal growth in alloys is limited by the morphological instability, which is caused by a positive feedback between the interface deformation and the diffusive flux of solute at the front of the phase transition. Usually this phenomenon is described in the framework of the normal diffusion equation, which stems from the linear relation between time and the mean squared displacement of molecules 〈x2(t)〉∼K1t (K1 is the classical diffusion coefficient) that is characteristic of Brownian motion. However, in some media (e.g., in gels and porous media) the random walk of molecules is hindered by obstacles, which leads to another power law, 〈x2(t)〉∼Kαtα, where 0<α≤1. As a result, the diffusion is anomalous, and it is governed by an integro-differential equation including a fractional derivative in time variable, i.e., a memory. In the present work, we investigate the stability of a directional solidification front in the case of an anomalous diffusion. Linear stability of a moving planar directional solidification front is studied, and a generalization of the Mullins-Sekerka stability criterion is obtained. Also, an asymptotic nonlinear long-wave evolution equation of Sivashinsky's type, which governs the cellular structures at the interface, is derived.

  3. Stability of a directional solidification front in subdiffusive media

    NASA Astrophysics Data System (ADS)

    Hamed, Mohammad Abu; Nepomnyashchy, Alexander A.

    2014-01-01

    The efficiency of crystal growth in alloys is limited by the morphological instability, which is caused by a positive feedback between the interface deformation and the diffusive flux of solute at the front of the phase transition. Usually this phenomenon is described in the framework of the normal diffusion equation, which stems from the linear relation between time and the mean squared displacement of molecules ˜K1t (K1 is the classical diffusion coefficient) that is characteristic of Brownian motion. However, in some media (e.g., in gels and porous media) the random walk of molecules is hindered by obstacles, which leads to another power law, ˜Kαtα, where 0<α≤1. As a result, the diffusion is anomalous, and it is governed by an integro-differential equation including a fractional derivative in time variable, i.e., a memory. In the present work, we investigate the stability of a directional solidification front in the case of an anomalous diffusion. Linear stability of a moving planar directional solidification front is studied, and a generalization of the Mullins-Sekerka stability criterion is obtained. Also, an asymptotic nonlinear long-wave evolution equation of Sivashinsky's type, which governs the cellular structures at the interface, is derived.

  4. Intraplate deformation due to continental collisions: A numerical study of deformation in a thin viscous sheet

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.; Morgan, R. C.

    1985-01-01

    A model of crustal deformation from continental collision that involves the penetration of a rigid punch into a deformable sheet is investigated. A linear viscous flow law is used to compute the magnitude and rate of change of crustal thickness, the velocity of mass points, strain rates and their principal axes, modes of deformation, areal changes, and stress. In general, a free lateral boundary reduces the magnitude of changes in crustal thickening by allowing material to more readily escape the advancing punch. The shearing that occurs diagonally in front of the punch terminates in compression or extension depending on whether the lateral boundary is fixed or free. When the ratio of the diameter of the punch to that of the sheet exceeds one-third, the deformation is insenstive to the choice of lateral boundary conditions. When the punch is rigid with sharply defined edges, deformation is concentrated near the punch corners. With non-rigid punches, shearing results in deformation being concentrated near the center of the punch. Variations with respect to linearity and nonlinearity of flow are discussed.

  5. Coupling of Activity at Neighbouring Volcanoes in Iceland: Ground Deformation and Activity at the Bárðarbunga-Tungnafellsjökull and Eyjafjallajökull-Katla Volcano Pairs

    NASA Astrophysics Data System (ADS)

    Parks, M.; Heimisson, E. R.; Sigmundsson, F.; Hooper, A. J.; Ofeigsson, B.; Vogfjord, K. S.; Arnadottir, T.; Dumont, S.; Drouin, V.; Bagnardi, M.; Spaans, K.; Hreinsdottir, S.; Friðriksdóttir, H. M.; Jonsdottir, K.; Guðmundsson, G.; Hensch, M.; Hjaltadottir, S.; Hjartardottir, A. R.; Einarsson, P.; Gudmundsson, M. T.; Hognadottir, T.; Lafemina, P.; Geirsson, H.; Sturkell, E.; Magnússon, E.

    2015-12-01

    Interferometric Synthetic Aperture Radar (InSAR) techniques are used to generate a time series of high-resolution deformation measurements, in the vicinity of two pairs of closely spaced volcanoes in Iceland: Bárðarbunga and Tungnafellsjökull, as well as Eyjafjallajökull and Katla. Following the declaration of Icelandic Volcanoes as a Permanent Geohazard Supersite in 2013, a considerable amount of SAR data was made available for both past and future satellite acquisitions, including new X-band images and historic C-band images. InSAR time series have been formed using these data and compared to other geodetic and microseismic measurements to determine the most likely processes responsible for recently observed deformation and/or seismicity. A comprehensive network of seismometers and continuous GPS stations are already deployed at these volcanoes and a series of campaign GPS measurements have been undertaken since 2010. We present an overview of the temporal variation in InSAR observations and these complementary field based measurements at Bárðarbunga and Tungnafellsjökull from 2014-2015 (covering the recent eruption at Holuhraun and contemporaneous slow collapse of the Bárðarbunga caldera), and Eyjafjallajökull and Katla volcanoes from 2010 onwards, after the 2010 explosive eruption of Eyjafjallajökull. We undertake a joint InSAR-GPS inversion using a Markov-chain Monte Carlo approach. The best-fit source geometries responsible for both the inflation of a 50 km long dyke and simultaneous deflation of the Bárðarbunga central volcano during the 2014-2015 unrest and eruption are found. Using these we calculate the stress changes associated with the Bárðarbunga deformation events and compare our results to the location of earthquake swarms in the vicinity of neighbouring Tungnafellsjökull, where seismic activity increased significantly following the onset of unrest at Bárðarbunga in August 2014. We also determine the optimal source parameters for

  6. Hydrothermal quartz formation during fluctuations of brittle shear-zone activity and fluid flow: grain growth and deformation structures of the Pfahl shear zone (Germany)

    NASA Astrophysics Data System (ADS)

    Yilmaz, T.; Prosser, G.; Liotta, D.; Kruhl, J. H.

    2012-12-01

    , crosscutting the first generations of fine-grained quartz mass and the wall rocks, in connection to intense fracturing and brecciation. The complex geometry of the vein sets points to multiple fluid injections and brecciation, as additionally indicated by coarse quartz with different inclusion and CL intensity. Temporal changes of strain rate are indicated by crystal plastic deformation structures in quartz, which overprint brittle structures. (iv) The fourth quartz generation occurs in mm- to dm-thick quartz veins, partly open as geodes, filling N-S oriented cm- to dm-spaced fractures that crosscut the earlier quartz masses and veins and extend at least several meters into the wall rock. They indicate the last activity of the shear-zone in a constant kinematic framework. Summarizing, the Pfahl shear zone shows brittle-ductile deformation during the long-term activity of a large-scale hydrothermal system. Consequently, it represents an excellent example where different generations of quartz precipitation can be connected to fluctuations of fluid flow and strain rate.

  7. Seabird diving behaviour reveals the functional significance of shelf-sea fronts as foraging hotspots

    NASA Astrophysics Data System (ADS)

    Cox, S. L.; Miller, P. I.; Embling, C. B.; Scales, K. L.; Bicknell, A. W. J.; Hosegood, P. J.; Morgan, G.; Ingram, S. N.; Votier, S. C.

    2016-09-01

    Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and cross-front gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems.

  8. Seabird diving behaviour reveals the functional significance of shelf-sea fronts as foraging hotspots

    PubMed Central

    Miller, P. I.; Embling, C. B.; Bicknell, A. W. J.; Hosegood, P. J.; Morgan, G.; Ingram, S. N.

    2016-01-01

    Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and cross-front gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems. PMID:27703698

  9. Deformation twinning: Influence of strain rate

    SciTech Connect

    Gray, G.T. III

    1993-11-01

    Twins in most crystal structures, including advanced materials such as intermetallics, form more readily as the temperature of deformation is decreased or the rate of deformation is increased. Both parameters lead to the suppression of thermally-activated dislocation processes which can result in stresses high enough to nucleate and grow deformation twins. Under high-strain rate or shock-loading/impact conditions deformation twinning is observed to be promoted even in high stacking fault energy FCC metals and alloys, composites, and ordered intermetallics which normally do not readily deform via twinning. Under such conditions and in particular under the extreme loading rates typical of shock wave deformation the competition between slip and deformation twinning can be examined in detail. In this paper, examples of deformation twinning in the intermetallics TiAl, Ti-48Al-lV and Ni{sub 3}A as well in the cermet Al-B{sub 4}C as a function of strain rate will be presented. Discussion includes: (1) the microstructural and experimental variables influencing twin formation in these systems and twinning topics related to high-strain-rate loading, (2) the high velocity of twin formation, and (3) the influence of deformation twinning on the constitutive response of advanced materials.

  10. Orogenic front propagation in the basement involved Malargüe fold and thrust belt, Neuquén Basin, (Argentina)

    NASA Astrophysics Data System (ADS)

    Branellec, Matthieu; Nivière, Bertrand; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2015-04-01

    The Malargüe fold and thrust belt (MFTB) and the San Rafael Block (SRB) are located in the northern termination of the Neuquén basin in Argentina. This basin is a wide inverted intracratonic sag basin with polyphased evolution controlled at large scale by the dynamic of the Pacific subduction. By late Triassic times, narrow rift basins developed and evolved toward a sag basin from middle Jurassic to late Cretaceous. From that time on, compression at the trench resulted in various shortening pulses in the back-arc area. Here we aim to analyze the Andean system at 35°S by comparing the Miocene structuration in the MFTB and the current deformation along the oriental border or the San Rafael Block. The main structuration stage in the MFTB occurred by Miocene times (15 to 10 Ma) producing the principal uplift of the Andean Cordillera. As shown by new structural cross sections, Triassic-early Jurassic rift border faults localized the Miocene compressive tectonics. Deformation is compartmentalized and does not exhibit a classical propagation of homogeneous deformation sequence expected from the critical taper theory. Several intramontane basins in the hangingwall of the main thrusts progressively disconnected from the foreland. In addition, active tectonics has been described in the front of the MFTB attesting for the on-going compression in this area. 100 km farther to the east, The San Rafael Block, is separated from the MFTB by the Rio Grande basin. The SRB is mostly composed of Paleozoic terranes and Triassic rift-related rocks, overlain by late Miocene synorogenic deposits. The SRB is currently uplifted along its oriental border along several active faults. These faults have clear morphologic signatures in Quaternary alluvial terraces and folded Pleistocene lavas. As in the MFTB, the active deformation localization remains localized by structural inheritance. The Andean system is thus evolving as an atypical orogenic wedge partly by frontal accretion at the front

  11. A HIGH FIDELITY SAMPLE OF COLD FRONT CLUSTERS FROM THE CHANDRA ARCHIVE

    SciTech Connect

    Owers, Matt S.; Nulsen, Paul E. J.; Markevitch, Maxim; Couch, Warrick J.

    2009-10-20

    This paper presents a sample of 'cold front' clusters selected from the Chandra archive. The clusters are selected based purely on the existence of surface brightness edges in their Chandra images which are modeled as density jumps. A combination of the derived density and temperature jumps across the fronts is used to select nine robust examples of cold front clusters: 1ES0657 - 558, Abell 1201, Abell 1758N, MS1455.0+2232, Abell 2069, Abell 2142, Abell 2163, RXJ1720.1+2638, and Abell 3667. This sample is the subject of an ongoing study aimed at relating cold fronts to cluster merger activity, and understanding how the merging environment affects the cluster constituents. Here, temperature maps are presented along with the Chandra X-ray images. A dichotomy is found in the sample in that there exists a subsample of cold front clusters which are clearly mergers based on their X-ray morphologies, and a second subsample of clusters which harbor cold fronts, but have surprisingly relaxed X-ray morphologies, and minimal evidence for merger activity at other wavelengths. For this second subsample, the existence of a cold front provides the sole evidence for merger activity at X-ray wavelengths. We discuss how cold fronts can provide additional information which may be used to constrain merger histories, and also the possibility of using cold fronts to distinguish major and minor mergers.

  12. Structural and erosional controls on exhumation across the southern Himalayan front, NW India

    NASA Astrophysics Data System (ADS)

    Thiede, R. C.; Ehlers, T. A.; Strecker, M. R.

    2006-12-01

    One of the premier research questions in the study active orogens is the role of climate and its potential influence on tectonic processes. The Himalayan orogen comprises well developed topographic, climatic, and erosional gradients, as well as a distinct zonation of physiographic provinces. These characteristics, active faulting, uplift, and superposed extreme climatic gradients associated with high monsoonal rainfall impinging on the southern mountain front make this region an ideal setting to evaluate the interaction between tectonics and surface processes at the scale of the orogen. Since the Indian/Eurasian collision began about 50 Ma ago, deformation in the Himalaya has been concentrated within a 200-km-wide zone. This zone is composed of three major tectonic, climatic, and topographic regions where: (1) the northern and internal part are characterized by high elevation (3-6 km a.s.l), moderate to steep relief and arid climate; (2) the High Himalaya, which constitutes high elevations (1.0-7 km a.s.l), steep relief and a humid climate; and (3) the Lesser Himalaya, with moderate elevation (0.5-3 km a.s.l), moderate relief, and a humid climate. We quantify the distribution of exhumation along the southern front of the Himalaya between the Bhagirati River (upper Ganges) in the east and the Sutlej River in the west. Twenty-five new and 103 previously published apatite fission track (AFT) samples are integrated to quantify spatial variations in exhumation within a 200 (E- W) x 100 (N-S) km wide segment of the southern Himalayan mountain front. The new ages range between 18 and <1 Ma and clusters in two age groups with a specific regional distribution: (a) AFT ages ranging between 10 and 5 Ma are characteristic for the Lesser Himalaya, whereas (b) ages along the southern front of the High Himalaya cluster between 3 and 0.5 Ma. The very young, and elevation-independent AFT cooling ages (<3 Ma) indicate a distinct and laterally extensive region of rapid rock uplift

  13. Shortening rates at the mountain front of the Andean Precordillera (Argentina) on timescales of millions, thousands and a few years

    NASA Astrophysics Data System (ADS)

    Salomon, E.; Mechernich, S.; Hetzel, R.; Mingorance, F.; Ramos, V. A.

    2012-12-01

    The eastern margin of the Andean Precordillera between 30 and 33°S is one of the most seismically active regions in the world and indicated several destructive earthquakes, e.g. a MS ~7.0 event destroyed Mendoza city in 1861. Modeled GPS data revealed a short-term shortening rate of ~2-5 mm/a at the wider Andean mountain front at 32-33°S (Brooks et al., 2003; Kendrick et al., 2006). Using only GPS stations directly east and west of the mountain front near Mendoza (33°S) results in a shortening of 2.8 ± 1.3 mm/a (Salomon et al., in rev.), implying that this rate is accommodated by the respective active frontal thrust. To investigate the significance of this GPS rate on longer timescales and to account for its accommodation on specific faults, we studied two range-bounding thrust faults near Mendoza, the 48-km-long Peñas and the 31-km-long Cal thrust, using fault scarp profiles, paleoseismic trenching and age determinations of the deformed terraces T1-T4. Fault scarps on the lowest terrace level T1 reveal vertical offsets of 0.8-1.0 m for both faults, which are interpreted as coseismic displacements during the last earthquakes (Mw~6.9). Older terraces show stepwise increasing cumulative offsets, indicating that elastic strain energy was repeatedly released during strong earthquakes. For example at the Peñas thrust the ~3.3-ka-old terrace T2 is offset by ~1.9 m and the ~12-ka-old terrace T3 is displaced by ~11 m (Schmidt et al., 2011). Thus, shortening along the Peñas thrust occurred at a rather constant rate of ~2.0 mm/a during the past ~12 ka; i.e. at a similar value as the present-day shortening at the mountain front. In contrast, the Cal thrust fault, which extends into Mendoza, indicates a shortening rate that accelerated recently from ≥0.9 mm/a to ~5.4 mm/a since three terraces vertically offset by ~2.6, ~3.6, and ~7.0 m, yielded ages of ~0.8 ka (OSL), ~3.9 ka (14C), and ≤12 ka (10Be) (Schmidt et al., 2011). However, caution is needed when regarding

  14. 1. VIEW SOUTHWARD FROM SOUTHWEST CORNER FRONT AND ARCH STREETS ...

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

    1. VIEW SOUTHWARD FROM SOUTHWEST CORNER FRONT AND ARCH STREETS (2. N. Front Street starts at left) - North Front Street Area Study, 2-66 North Front Street (Commercial Buildings), Philadelphia, Philadelphia County, PA

  15. Front and backside processed thin film electronic devices

    DOEpatents

    Evans, Paul G.; Lagally, Max G.; Ma, Zhenqiang; Yuan, Hao-Chih; Wang, Guogong; Eriksson, Mark A.

    2012-01-03

    This invention provides thin film devices that have been processed on their front- and backside. The devices include an active layer that is sufficiently thin to be mechanically flexible. Examples of the devices include back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

  16. Marangoni instability in the iodate-arsenous acid reaction front

    NASA Astrophysics Data System (ADS)

    Pópity-Tóth, Éva; Pótári, Gábor; Erdős, István; Horváth, Dezső; Tóth, Ágota

    2014-07-01

    Horizontally propagating chemical fronts leading to the formation of a single stable convection roll are investigated in the iodate-arsenous acid reaction with arsenous acid stoichiometrically limiting, leaving the surface active iodine present in the product mixture. In sufficiently thin solution layers with open upper surface, the contribution of Marangoni instability is significantly enhanced. Acting in the same direction as buoyancy driven instability, it distorts the entire tilted reaction front that becomes 50% more elongated. The corresponding three-dimensional calculations based on the empirical rate-law of the reaction corroborate the experimental findings.

  17. Marangoni instability in the iodate–arsenous acid reaction front

    SciTech Connect

    Pópity-Tóth, Éva; Pótári, Gábor; Erdős, István; Tóth, Ágota; Horváth, Dezső

    2014-07-28

    Horizontally propagating chemical fronts leading to the formation of a single stable convection roll are investigated in the iodate–arsenous acid reaction with arsenous acid stoichiometrically limiting, leaving the surface active iodine present in the product mixture. In sufficiently thin solution layers with open upper surface, the contribution of Marangoni instability is significantly enhanced. Acting in the same direction as buoyancy driven instability, it distorts the entire tilted reaction front that becomes 50% more elongated. The corresponding three-dimensional calculations based on the empirical rate-law of the reaction corroborate the experimental findings.

  18. Relating Global Precipitation to Atmospheric Fronts

    NASA Astrophysics Data System (ADS)

    Catto, J. L.; Jakob, C.; Nicholls, N.

    2012-12-01

    Atmospheric fronts are important for the day-to-day variability of weather in the midlatitudes, particularly during winter when extratropical storm-tracks are at their maximum intensity. Fronts are often associated with heavy rain, and strongly affect the local space-time distribution of rainfall. Although global climate models should be expected to represent the baroclinic systems within which the fronts are embedded, the fronts themselves and precipitation processes within them are of much smaller scale. As a consequence, models with the typical horizontal resolution of contemporary climate models do not necessarily accurately capture these features. A recently developed objective front identification method applied to reanalysis data is combined with global rainfall data to investigate how precipitation and extremes of precipitation around the globe are associated with atmospheric fronts. Having established the observed distribution of fronts and their role in producing precipitation and extremes, the occurrence of fronts and the associated precipitation can then be evaluated in state-of-the-art climate models. This provides a process-oriented method of model evaluation where the errors in the model can be decomposed into contributions from errors in front frequency and errors in frontal and non-frontal precipitation intensity. Finally, how fronts and their associated precipitation, may change in the future, especially the extremes, can be investigated.

  19. Laser-supported solid-state absorption fronts in silica

    NASA Astrophysics Data System (ADS)

    Carr, C. W.; Bude, J. D.; Demange, P.

    2010-11-01

    We develop a model based on simulation and extensive experimentation that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm2 ) laser exposure. Both experiments and simulations show that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. We show that these absorption fronts naturally result from the combination of high-temperature-activated deep subband-gap optical absorptivity, free-electron transport, and thermal diffusion in defect-free silica for temperatures up to 15000K and pressures <10GPa . The regime of parameter space critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

  20. Propagation failures, breathing fronts, and nonannihilation collisions in the ferroin-bromate-pyrocatechol system.

    PubMed

    Harati, Mohammad; Wang, Jichang

    2009-06-01

    The emergence of propagating pulses was investigated with the photosensitive ferroin-bromate-pyrocatechol reaction in capillary tubes, in which various interesting spatiotemporal behaviors such as propagation failure, breathing fronts, and transitions between propagating pulses and fronts have been observed. Rather than a mutual annihilation, the collision of a propagating pulse and a growing front forces the front to recede gradually. A phase diagram in the pyrocatechol-bromate concentration space shows that the pulse instabilities take place throughout the conditions at which the system generates wave activities, suggesting that the presence of coupled autocatalytic feedbacks may facilitate the onset of pulse instabilities.

  1. Light-Front Holographic QCD

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    The relation between the hadronic short-distance constituent quark and gluon particle limit and the long-range confining domain is yet one of the most challenging aspects of particle physics due to the strong coupling nature of Quantum Chromodynamics, the fundamental theory of the strong interactions. The central question is how one can compute hadronic properties from first principles; i.e., directly from the QCD Lagrangian. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time. Lattice numerical results follow from computation of frame-dependent moments of distributions in Euclidean space and dynamical observables in Minkowski spacetime, such as the time-like hadronic form factors, are not amenable to Euclidean lattice computations. The Dyson-Schwinger methods have led to many important insights, such as the infrared fixed point behavior of the strong coupling constant, but in practice, the analyses are limited to ladder approximation in Landau gauge. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. New theoretical tools are thus of primary interest for the interpretation of the results expected at the new mass scale and kinematic regions accessible to the JLab 12 GeV Upgrade Project. The AdS/CFT correspondence between gravity or string theory on a higher-dimensional anti-de Sitter (AdS) space and conformal field theories in physical space-time has led to a semiclassical approximation for strongly-coupled QCD, which provides physical insights into its nonperturbative dynamics. The correspondence is holographic in the sense that it determines a duality between theories in different number of space-time dimensions. This geometric approach leads in fact to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front

  2. Analysis of Slip Activity and Deformation Modes in Tension and Tension-Creep Tests of Cast Mg-10Gd-3Y-0.5Zr (Wt Pct) at Elevated Temperatures Using In Situ SEM Experiments

    NASA Astrophysics Data System (ADS)

    Wang, Huan; Boehlert, Carl J.; Wang, Qudong; Yin, Dongdi; Ding, Wenjiang

    2016-05-01

    The tension and tension-creep deformation behavior at elevated temperatures of a cast Mg-10Gd-3Y-0.5Zr (wt pct, GW103) alloy was investigated using in situ scanning electron microscopy. The tests were performed at temperatures ranging from 473 K to 598 K (200 °C to 325 °C). The active slip systems were identified using an EBSD-based slip trace analysis methodology. The results showed that for all of the tests, basal slip was the most likely system to be activated, and non-basal slip was activated to some extent depending on the temperature. No twinning was observed. For the tension tests, non-basal slip consisted of ~35 pct of the deformation modes at low temperatures (473 K and 523 K (200 °C and 250 °C)), while non-basal slip accounted for 12 and 7 pct of the deformation modes at high temperatures (573 K and 598 K (300 °C and 325 °C)), respectively. For the tension-creep tests, non-basal slip accounted for 31 pct of the total slip systems at low temperatures, while this value decreased to 10 to 16 pct at high temperatures. For a given temperature, the relative activity for prismatic slip in the tension-creep tests was slightly greater than that for the tension tests, while the activity for pyramidal slip was lower. Slip-transfer in neighboring grains was observed for the low-temperature tests. Intergranular cracking was the main cracking mode, while some intragranular cracks were observed for the tension-creep tests at high temperature and low stress. Grain boundary ledges were prevalently observed for both the tension and tension-creep tests at high temperatures, which suggests that besides dislocation slip, grain boundary sliding also contributed to the deformation.

  3. Deformable bearing seat

    NASA Technical Reports Server (NTRS)

    Moreman, O. S., III (Inventor)

    1977-01-01

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

  4. What's New in Severe Deformity Correction: The German Perspective.

    PubMed

    Schmitt, Sebastian; Peak, Anna C; Berrsche, Gregor; Wenz, Wolfram

    2016-06-01

    Foot deformities are found in several neurologic conditions, most typically, but not exclusively, Charcot-Marie-Tooth disease. Posttraumatic deformities and undercorrection or overcorrection of congenital talipes equinovarus are also encountered. A severely deformed foot that cannot fit into normal shoes presents a significant day-to-day challenge to the young and active patient. This article presents some basic principles for evaluating the deformity and a toolkit of procedures to deal with these complex cases. PMID:27261803

  5. Deformed discrete symmetries

    NASA Astrophysics Data System (ADS)

    Arzano, Michele; Kowalski-Glikman, Jerzy

    2016-09-01

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

  6. Fluctuations as stochastic deformation

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2008-04-01

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

  7. Fluctuations as stochastic deformation.

    PubMed

    Kazinski, P O

    2008-04-01

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

  8. Front propagation and rejuvenation in flipping processes

    SciTech Connect

    Ben-naim, Eli; Krapivsky, P I; Antal, T; Ben - Avrahm, D

    2008-01-01

    We study a directed flipping process that underlies the performance of the random edge simplex algorithm. In this stochastic process, which takes place on a one-dimensional lattice whose sites may be either occupied or vacant, occupied sites become vacant at a constant rate and simultaneously cause all sites to the right to change their state. This random process exhibits rich phenomenology. First, there is a front, defined by the position of the leftmost occupied site, that propagates at a nontrivial velocity. Second, the front involves a depletion zone with an excess of vacant sites. The total excess {Delta}{sub k} increases logarithmically, {Delta}{sub k} {approx_equal}ln k, with the distance k from the front. Third, the front exhibits ageing -- young fronts are vigorous but old fronts are sluggish. We investigate these phenomena using a quasi-static approximation, direct solutions of small systems and numerical simulations.

  9. Condensation Front Migration in a Protoplanetary Nebula

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.

    2004-01-01

    Condensation front dynamics are investigated in the mid-solar nebula region. A quasi-steady model of the evolving nebula is combined with equilibrium vapor pressure curves to determine evolutionary condensation fronts for selected species. These fronts are found to migrate inwards from the far-nebula to final positions during a period of 10(exp 7) years. The physical process governing this movement is a combination of local viscous heating and luminescent heating from the central star. Two luminescent heating models are used and their effects on the ultimate radial position of the condensation front are discussed. At first the fronts move much faster than the nebular accretion velocity, but after a time the accreting gas and dust overtakes the slowing condensation front.

  10. Progress in front propagation research

    NASA Astrophysics Data System (ADS)

    Fort, Joaquim; Pujol, Toni

    2008-08-01

    We review the progress in the field of front propagation in recent years. We survey many physical, biophysical and cross-disciplinary applications, including reduced-variable models of combustion flames, Reid's paradox of rapid forest range expansions, the European colonization of North America during the 19th century, the Neolithic transition in Europe from 13 000 to 5000 years ago, the description of subsistence boundaries, the formation of cultural boundaries, the spread of genetic mutations, theory and experiments on virus infections, models of cancer tumors, etc. Recent theoretical advances are unified in a single framework, encompassing very diverse systems such as those with biased random walks, distributed delays, sequential reaction and dispersion, cohabitation models, age structure and systems with several interacting species. Directions for future progress are outlined.

  11. The upgraded Tevatron front end

    NASA Astrophysics Data System (ADS)

    Glass, M.; Zagel, J.; Smith, P.; Marsh, W.; Smolucha, J.

    1990-08-01

    We are replacing the computers which support the CAMAC crates in the Fermilab accelerator control system. We want a significant performance increase, but we still want to be able to service scores of different varieties of CAMAC cards in a manner essentially transparent to console applications software. Our new architecture is based on symmetric multiprocessing. Several processors on the same bus, each running identical software, work simultaneously at satisfying different pieces of a console's request for data. We dynamically adjust the load between the processors. We can obtain more processing power by simply plugging in more processors cards and rebooting. We describe in this paper what we believe to be the interesting architectural features of the new front-end computers. We also note how we use some of the advanced features of the Multibus™ II bus and the Intel 80386 processor design to achieve reliability and expandability of both hardware and software.

  12. Developing a Virtual Rock Deformation Laboratory

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Ougier-simonin, A.; Lisabeth, H. P.; Banker, J. S.

    2012-12-01

    Experimental rock physics plays an important role in advancing earthquake research. Despite its importance in geophysics, reservoir engineering, waste deposits and energy resources, most geology departments in U.S. universities don't have rock deformation facilities. A virtual deformation laboratory can serve as an efficient tool to help geology students naturally and internationally learn about rock deformation. Working with computer science engineers, we built a virtual deformation laboratory that aims at fostering user interaction to facilitate classroom and outreach teaching and learning. The virtual lab is built to center around a triaxial deformation apparatus in which laboratory measurements of mechanical and transport properties such as stress, axial and radial strains, acoustic emission activities, wave velocities, and permeability are demonstrated. A student user can create her avatar to enter the virtual lab. In the virtual lab, the avatar can browse and choose among various rock samples, determine the testing conditions (pressure, temperature, strain rate, loading paths), then operate the virtual deformation machine to observe how deformation changes physical properties of rocks. Actual experimental results on the mechanical, frictional, sonic, acoustic and transport properties of different rocks at different conditions are compiled. The data acquisition system in the virtual lab is linked to the complied experimental data. Structural and microstructural images of deformed rocks are up-loaded and linked to different deformation tests. The integration of the microstructural image and the deformation data allows the student to visualize how forces reshape the structure of the rock and change the physical properties. The virtual lab is built using the Game Engine. The geological background, outstanding questions related to the geological environment, and physical and mechanical concepts associated with the problem will be illustrated on the web portal. In

  13. Muon front end for the neutrino factory

    NASA Astrophysics Data System (ADS)

    Rogers, C. T.; Stratakis, D.; Prior, G.; Gilardoni, S.; Neuffer, D.; Snopok, P.; Alekou, A.; Pasternak, J.

    2013-04-01

    In the neutrino factory, muons are produced by firing high-energy protons onto a target to produce pions. The pions decay to muons and pass through a capture channel known as the muon front end, before acceleration to 12.6 GeV. The muon front end comprises a variable frequency rf system for longitudinal capture and an ionization cooling channel. In this paper we detail recent improvements in the design of the muon front end.

  14. The 2006 Bahía Asunción Earthquake Swarm: Seismic Evidence of Active Deformation Along the Western Margin of Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Munguía, Luis; Mayer, Sergio; Aguirre, Alfredo; Méndez, Ignacio; González-Escobar, Mario; Luna, Manuel

    2015-10-01

    The study of the Bahía Asunción earthquake swarm is important for two reasons. First, the earthquakes are clear evidence of present activity along the zone of deformation on the Pacific margin of Baja California. The swarm, with earthquakes of magnitude M w of up to 5.0, occurred on the coastline of the peninsula, showing that the Tosco-Abreojos zone of deformation is wider than previously thought. Second, the larger earthquakes in the swarm caused some damage and much concern in Bahía Asunción, a small town located in the zone of epicenters. We relocated the larger earthquakes with regional and/or local seismic data. Our results put the earthquake sources below the urban area of Bahía Asunción, at 40-50 km to the north of the teleseismically determined epicenters. In addition, these new locations are in the area of epicenters of many smaller events that were located with data from local temporary stations. This area trends in an E-W direction and has dimensions of approximately 15 km by 10 km. Most earthquakes had sources at depths that are between 4 and 9 km. A composite focal mechanism for the smaller earthquakes indicated right-lateral strike-slip motion and pure-normal faulting occurred during this swarm. Interestingly, the ANSS earthquake catalog of the United States Geological Survey (USGS) reported each one of these faulting styles for two large events of the swarm, with one of these earthquakes occurring 2 days before the other one. We associate the earthquake with strike-slip mechanism with the San Roque Fault, and the earthquake with the normal faulting style with the Asunción Fault. However, there is need of further study to verify this possible relation between the faults and the earthquakes. In addition, we recorded peak accelerations of up to 0.63g with an accelerometer installed in Bahía Asunción. At this site, an earthquake of M w 4.9 produced those high values at a distance of 4.1 km. We also used the acceleration dataset from this site

  15. The 2006 Bahía Asunción Earthquake Swarm: Seismic Evidence of Active Deformation Along the Western Margin of Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Munguía, Luis; Mayer, Sergio; Aguirre, Alfredo; Méndez, Ignacio; González-Escobar, Mario; Luna, Manuel

    2016-10-01

    The study of the Bahía Asunción earthquake swarm is important for two reasons. First, the earthquakes are clear evidence of present activity along the zone of deformation on the Pacific margin of Baja California. The swarm, with earthquakes of magnitude M w of up to 5.0, occurred on the coastline of the peninsula, showing that the Tosco-Abreojos zone of deformation is wider than previously thought. Second, the larger earthquakes in the swarm caused some damage and much concern in Bahía Asunción, a small town located in the zone of epicenters. We relocated the larger earthquakes with regional and/or local seismic data. Our results put the earthquake sources below the urban area of Bahía Asunción, at 40-50 km to the north of the teleseismically determined epicenters. In addition, these new locations are in the area of epicenters of many smaller events that were located with data from local temporary stations. This area trends in an E-W direction and has dimensions of approximately 15 km by 10 km. Most earthquakes had sources at depths that are between 4 and 9 km. A composite focal mechanism for the smaller earthquakes indicated right-lateral strike-slip motion and pure-normal faulting occurred during this swarm. Interestingly, the ANSS earthquake catalog of the United States Geological Survey (USGS) reported each one of these faulting styles for two large events of the swarm, with one of these earthquakes occurring 2 days before the other one. We associate the earthquake with strike-slip mechanism with the San Roque Fault, and the earthquake with the normal faulting style with the Asunción Fault. However, there is need of further study to verify this possible relation between the faults and the earthquakes. In addition, we recorded peak accelerations of up to 0.63 g with an accelerometer installed in Bahía Asunción. At this site, an earthquake of M w 4.9 produced those high values at a distance of 4.1 km. We also used the acceleration dataset from this site

  16. Front blind spot crashes in Hong Kong.

    PubMed

    Cheng, Yuk Ki; Wong, Koon Hung; Tao, Chi Hang; Tam, Cheok Ning; Tam, Yiu Yan; Tsang, Cheuk Nam

    2016-09-01

    In 2012-2014, our laboratory had investigated a total of 9 suspected front blind spot crashes, in which the medium and heavy goods vehicles pulled away from rest and rolled over the pedestrians, who were crossing immediately in front of the vehicles. The drivers alleged that they did not see any pedestrians through the windscreens or the front blind spot mirrors. Forensic assessment of the goods vehicles revealed the existence of front blind spot zones in 3 out of these 9 accident vehicles, which were attributed to the poor mirror adjustments or even the absence of a front blind spot mirror altogether. In view of this, a small survey was devised involving 20 randomly selected volunteers and their goods vehicles and 5 out of these vehicles had blind spots at the front. Additionally, a short questionnaire was conducted on these 20 professional lorry drivers and it was shown that most of them were not aware of the hazards of blind spots immediately in front of their vehicles, and many did not use the front blind spot mirrors properly. A simple procedure for quick measurements of the coverage of front blind spot mirrors using a coloured plastic mat with dimensional grids was also introduced and described in this paper.

  17. Helices in the wake of precipitation fronts.

    PubMed

    Thomas, Shibi; Lagzi, István; Molnár, Ferenc; Rácz, Zoltán

    2013-08-01

    A theoretical study of the emergence of helices in the wake of precipitation fronts is presented. The precipitation dynamics is described by the Cahn-Hilliard equation and the fronts are obtained by quenching the system into a linearly unstable state. Confining the process onto the surface of a cylinder and using the pulled-front formalism, our analytical calculations show that there are front solutions that propagate into the unstable state and leave behind a helical structure. We find that helical patterns emerge only if the radius of the cylinder R is larger than a critical value R>R(c), in agreement with recent experiments. PMID:24032809

  18. Shear zone nucleation and deformation transient: effect of heterogeneities and loading conditions in experimentally deformed calcite

    NASA Astrophysics Data System (ADS)

    Morales, L. F. G.; Rybacki, E.; Dresen, G. H.; Kilian, R.

    2015-12-01

    In the Earth's middle to lower crust, strain is frequently localized along ductile shear zones, which commonly nucleate at structural and material heterogeneities. To investigate shear zone nucleation and development due to heterogeneities, we performed constant strain-rate (CSR) and constant stress (CS) simple shear (torsion) deformation experiments on Carrara marble samples containing weak (limestone) inclusions. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure and maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. In CS tests a narrow shear zone developed in front of the inclusion, whereas in CSR experiments the deformation is more heterogeneously distributed, up to g=3.. In the later, secondary foliations oblique to the process zone and alternating thin, high-strain layers are common. In samples deformed at the same shear strain (g=1), the average recrystallized grain size in the process zone is similar for CS and CSR conditions. Crystallographic preferred orientation (CPO) measurements shows that different grain sizes have slightly different CPO patterns. CPO strength varies for different grain sizes, with a CPO strength peak between 40-50 μm, decreasing progressively within smaller grain size, but with secondary peaks for different coarse-grained sizes. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  19. Resurgent deformation quantisation

    SciTech Connect

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

    2014-03-15

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

  20. PS-InSAR measurements at the most active volcanoes in Iceland: role of the GEO supersite initiative in deformation monitoring at Bárðarbunga, Askja, Hekla, Katla and Eyjafjallajökull volcanoes

    NASA Astrophysics Data System (ADS)

    Parks, Michelle; Dumont, Stéphanie; Drouin, Vincent; Sigmundsson, Freysteinn; Spaans, Karsten; Hooper, Andrew; Ófeigsson, Benedikt; Árnadóttir, Þóra; Hreinsdóttir, Sigrún; Michalczewska, Karolina; Hjaltadóttir, Sigurlaug; María Friðriksdóttir, Hildur; Rut Hjartardóttir, Ásta; Magnússon, Eyjólfur; Vogfjörd, Kristín; Jónsdóttir, Kristín; Hensch, Martin; Guðmundsson, Gunnar; Geirsson, Halldór; Sturkell, Erik

    2015-04-01

    Analysis of a time series of ground deformation measurements at active volcanoes can provide an improved understanding of sub-volcanic and sub-aerial processes; including those related to magmatic, hydrothermal and structural development. Interpreting a long time series may also help determine background behavior, and identify any deviations from this, including the migration of new melt. We use Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques to generate a time series of high-resolution deformation measurements, in the vicinity of the most active volcanoes in Iceland: Bárðarbunga, Askja, Hekla, Katla and Eyjafjallajökull and compare these to other geodetic measurements. A comprehensive network of continuous GPS stations is already deployed at these volcanoes and a series of campaign GPS measurements are routinely undertaken each summer. InSAR observations are complementary to these field based measurements and their high spatial resolution assists in resolving the geometry of the deformation field hence gaining improved constraints on the inferred source. The Committee on Earth Observation Satellites has recently declared Iceland a Permanent Geohazard Supersite, based on its propensity for relatively frequent eruptions and their potentially hazardous, long ranging effects. The recent Supersite award ensures a considerable amount of SAR data is made available for both past and future satellite acquisitions, including new X-band images (acquired by TerraSAR-X and Cosmo-SkyMed satellites), and historic C-band images from ERS and ENVISAT. We present a series of long-term deformation measurements for Hekla, Katla, Eyjafjallajökull and Askja volcanoes, derived using PS-InSAR techniques, and include recent interferograms spanning the 2014 unrest and eruption within the Bárðarbunga volcanic system. InSAR and tilt measurements at Hekla indicate renewed melt supply to a sub-volcanic reservoir after the last eruption in 2000. Recent

  1. Wave front fragmentation due to ventricular geometry in a model of the rabbit heart

    NASA Astrophysics Data System (ADS)

    Rogers, Jack M.

    2002-09-01

    The role of the heart's complex shape in causing the fragmentation of activation wave fronts characteristic of ventricular fibrillation (VF) has not been well studied. We used a finite element model of cardiac propagation capable of simulating functional reentry on curved two-dimensional surfaces to test the hypothesis that uneven surface curvature can cause local propagation block leading to proliferation of reentrant wave fronts. We found that when reentry was induced on a flat sheet, it rotated in a repeatable meander pattern without breaking up. However, when a model of the rabbit ventricles was formed from the same medium, reentrant wave fronts followed complex, nonrepeating trajectories. Local propagation block often occurred when wave fronts propagated across regions where the Gaussian curvature of the surface changed rapidly. This type of block did not occur every time wave fronts crossed such a region; rather, it only occurred when the wave front was very close behind the previous wave in the cycle and was therefore propagating into relatively inexcitable tissue. Close wave front spacing resulted from nonstationary reentrant propagation. Thus, uneven surface curvature and nonstationary reentrant propagation worked in concert to produce wave front fragmentation and complex activation patterns. None of the factors previously thought to be necessary for local propagation block (e.g., heterogeneous refractory period, steep action potential duration restitution) were present. We conclude that the complex geometry of the heart may be an important determinant of VF activation patterns.

  2. Shape memory composite deformable mirrors

    NASA Astrophysics Data System (ADS)

    Riva, M.; Bettini, P.; Di Landro, L.; Sala, G.

    2009-03-01

    This paper deals with some of the critical aspects regarding Shape Memory Composite (SMC) design: firstly some technological aspects concerning embedding technique and their efficiency secondarily the lack of useful numerical tools for this peculiar design. It has been taken into account as a possible application a deformable panel which is devoted to act as a substrate for a deformable mirror. The activity has been mainly focused to the study of embedding technologies, activation and authority. In detail it will be presented the "how to" manufacturing of some smart panels with embedded NiTiNol wires in order to show the technology developed for SMC structures. The first part of the work compares non conventional pull-out tests on wires embedded in composites laminates (real condition of application), with standard pull-out in pure epoxy resin blocks. Considering the numerical approach some different modeling techniques to be implemented in commercial codes (ABAQUS) have been investigated. The Turner's thermo-mechanical model has been adopted for the modeling of the benchmark: A spherical panel devoted to work as an active substrate for a Carbon Fiber Reinforced Plastic (CFRP) deformable mirror has been considered as a significant technological demonstrator and possible future application (f=240mm, r.o.c.=1996mm).

  3. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

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

  4. Fault-based PSHA of an active tectonic region characterized by low deformation rates: the case of the Lower Rhine Graben

    NASA Astrophysics Data System (ADS)

    Vanneste, Kris; Vleminckx, Bart; Camelbeeck, Thierry

    2016-04-01

    The Lower Rhine Graben (LRG) is one of the few regions in intraplate NW Europe where seismic activity can be linked to active faults, yet probabilistic seismic hazard assessments of this region have hitherto been based on area-source models, in which the LRG is modeled as a single or a small number of seismotectonic zones with uniform seismicity. While fault-based PSHA has become common practice in more active regions of the world (e.g., California, Japan, New Zealand, Italy), knowledge of active faults has been lagging behind in other regions, due to incomplete tectonic inventory, low level of seismicity, lack of systematic fault parameterization, or a combination thereof. The past few years, efforts are increasingly being directed to the inclusion of fault sources in PSHA in these regions as well, in order to predict hazard on a more physically sound basis. In Europe, the EC project SHARE ("Seismic Hazard Harmonization in Europe", http://www.share-eu.org/) represented an important step forward in this regard. In the frame of this project, we previously compiled the first parameterized fault model for the LRG that can be applied in PSHA. We defined 15 fault sources based on major stepovers, bifurcations, gaps, and important changes in strike, dip direction or slip rate. Based on the available data, we were able to place reasonable bounds on the parameters required for time-independent PSHA: length, width, strike, dip, rake, slip rate, and maximum magnitude. With long-term slip rates remaining below 0.1 mm/yr, the LRG can be classified as a low-deformation-rate structure. Information on recurrence interval and elapsed time since the last major earthquake is lacking for most faults, impeding time-dependent PSHA. We consider different models to construct the magnitude-frequency distribution (MFD) of each fault: a slip-rate constrained form of the classical truncated Gutenberg-Richter MFD (Anderson & Luco, 1983) versus a characteristic MFD following Youngs

  5. The APS beamline front end vacuum system

    SciTech Connect

    Nielsen, R.W.

    1993-10-15

    This report discusses the design of the vacuum system for the advanced photon source beamline front ends. Included in this report are discussions on: vacuum calculations, the differential pump; front end vacuum set points; cleaning methods and agents; and continuing and completed research and development.

  6. Fluid evolution at the Variscan front in the vicinity of the Aachen thrust

    NASA Astrophysics Data System (ADS)

    Sindern, S.; Meyer, F. M.; Lögering, M. J.; Kolb, J.; Vennemann, T.; Schwarzbauer, J.

    2012-01-01

    Quartz-carbonate-chlorite veins were studied in borehole samples of the RWTH-1 well in Aachen. Veins formed in Devonian rocks in the footwall of the Aachen thrust during Variscan deformation and associated fluid flow. Primary fluid inclusions indicate subsolvus unmixing of a homogenous H2O-CO2-CH4-(N2)-Na-(K)-Cl fluid into a H2O-Na-(K)-Cl solution and a vapour-rich CO2-(H2O, CH4, N2) fluid. The aqueous end-member composition resembles that of metamorphic fluids of the Variscan front zone with salinities ranging from 4 to 7% NaCl equiv. and maximum homogenisation temperatures of close to 400°C. Pressure estimates indicate a burial depth between 4,500 and 8,000 m at geothermal gradients between 50 and 75°C/26 MPa, but pressure decrease to sublithostatic conditions is also indicated, probably as a consequence of fracture opening during episodic seismic activity. A second fluid system, mainly preserved in pseudo-secondary and secondary fluid inclusions, is characterised by fluid temperatures between 200 and 250°C and salinities of <5% NaCl equiv. Bulk stable isotope analyses of fluids released from vein quartz, calcite, and dolomite by decrepitation yielded δDH2O values from -89 to -113 ‰, δ13CCH4 from -26.9 to -28.9‰ (VPDB) and δ13CCO2 from -12.8 to -23.3‰ (VPDB). The low δD and δ13C range of the fluids is considered to be due to interaction with cracked hydrocarbons. The second fluid influx caused partial isotope exchange and disequilibrium. It is envisaged that an initial short lived flux of hot metamorphic fluids expelled from the epizonal metamorphic domains of the Stavelot-Venn massif. The metamorphic fluid was focused along major thrust faults of the Variscan front zone such as the Aachen thrust. A second fluid influx was introduced from formation waters in the footwall of the Aachen thrust as a consequence of progressive deformation. Mixing of the cooler and lower salinity formation water with the hot metamorphic fluid during episodic fluid

  7. On a theory of the evolution of surface cold fronts

    NASA Technical Reports Server (NTRS)

    Levy, Gad; Bretherton, Christopher S.

    1987-01-01

    The governing vorticity and divergence equations in the surface layer are derived and the roles of the different terms and feedback mechanisms are investigated in semigeostrophic and nongeostrophic cold-frontal systems. A planetary boundary layer model is used to perform sensitivity tests to determine that in a cold front the ageostrophic feedback mechanism as defined by Orlanski and Ross tends to act as a positive feedback mechanism, enhancing vorticity and convergence growth. Therefore, it cannot explain the phase shift between convergence and vorticity as simulated by Orlanski and Ross. An alternative plausible, though tentative, explanation in terms of a gravity wave is offered. It is shown that when the geostrophic deformation increases, nonlinear terms in the divergence equation may become important and further destabilize the system.

  8. Observations of Gravity Waves at Atmospheric Fronts

    NASA Astrophysics Data System (ADS)

    Abu Samah, Azizan B. Hj.

    1990-01-01

    Available from UMI in association with The British Library. An observational study of pressure perturbations associated with the passage of atmospheric fronts over the British Isles using a triangular array of sensitive microbarographs reveals the preponderance of gravity wave activities in the vicinity of the surface cold front (SCF). Examination of the time series of these pressure perturbations in the frequency domain shows an enhancement for frequencies less than the local buoyancy frequency N after the passage of the SCF. The spectral analysis also shows two predominant frequency peaks usually located near N and N/2 s ^{-1}. Isolating these frequencies shows that there is a systematic amplitude modulation with an amplification near the SCF and at a region 2-3 hours before and after the SCF passage. The cross-correlation analysis reveals that the gravity waves in the post SCF region propagate towards the SCF. As these waves approach the SCF, the across front component of the phase speed decreases and the direction of propagation of the wave rotates in an anticlockwise manner. It is found that a consistent description of the gravity waves can only be made if first the waves are assumed to be ducted, i.e. there is a reflecting layer aloft, and second that as these waves propagate through the frontal environment, due to the inhomogeneity, they are refracted. A number of conceptual models are then developed to account for the observed wave behaviour in a frontal region. In this investigation it is shown that the stable layer associated with the frontal zone can form a good upper reflector for non-hydrostatic gravity waves. It is also argued that the slope of this layer plays an important role in the refraction of the observed gravity waves. A model of wave propagation in a wedge is then used to account for this slope. This model however predicts a clockwise rotation of the direction of propagation as the wave propagates toward the SCF. This rotation is the opposite

  9. Front end for GPS receivers

    NASA Technical Reports Server (NTRS)

    Thomas, Jr., Jess Brooks (Inventor)

    1999-01-01

    The front end in GPS receivers has the functions of amplifying, down-converting, filtering and sampling the received signals. In the preferred embodiment, only two operations, A/D conversion and a sum, bring the signal from RF to filtered quadrature baseband samples. After amplification and filtering at RF, the L1 and L2 signals are each sampled at RF at a high selected subharmonic rate. The subharmonic sample rates are approximately 900 MHz for L1 and 982 MHz for L2. With the selected subharmonic sampling, the A/D conversion effectively down-converts the signal from RF to quadrature components at baseband. The resulting sample streams for L1 and L2 are each reduced to a lower rate with a digital filter, which becomes a straight sum in the simplest embodiment. The frequency subsystem can be very simple, only requiring the generation of a single reference frequency (e.g. 20.46 MHz minus a small offset) and the simple multiplication of this reference up to the subharmonic sample rates for L1 and L2. The small offset in the reference frequency serves the dual purpose of providing an advantageous offset in the down-converted carrier frequency and in the final baseband sample rate.

  10. Relativistic ionization fronts in gas jets

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Dias, J. M.; Gallacher, J. G.; Issac, R. C.; Fonseca, R. A.; Lopes, N. C.; Silva, L. O.; Mendonça, J. T.; Jaroszynski, D. A.

    2006-10-01

    A high-power ultra-short laser pulse propagating through a gas jet, ionizes the gas by tunnelling ionization, creating a relativistic plasma-gas interface. The relativistic ionization front that is created can be used to frequency up-shift electromagnetic radiation either in co-propagation or in counter-propagation configurations. In the counter-propagation configuration, ionization fronts can act as relativistic mirrors for terahertz radiation, leading to relativistic double Doppler frequency up-shift to the visible range. In this work, we identified and explored, the parameters that optimize the key features of relativistic ionization fronts for terahertz radiation reflection. The relativistic ionization front generated by a high power laser (TOPS) propagating in a supersonic gas jet generated by a Laval nozzle has been fully characterized. We have also performed detailed two-dimensional relativistic particle-in-cell simulations with Osiris 2.0 to analyze the generation and propagation of the ionization fronts.

  11. Coherent structures for front propagation in fluids

    NASA Astrophysics Data System (ADS)

    Mitchell, Kevin; Mahoney, John

    2014-03-01

    Our goal is to characterize the nature of reacting flows by identifying important ``coherent'' structures. We follow the recent work by Haller, Beron-Vera, and Farazmand which formalized the notion of lagrangian coherent structures (LCSs) in fluid flows. In this theory, LCSs were derived from the Cauchy-Green strain tensor. We adapt this perspective to analogously define coherent structures in reacting flows. By this we mean a fluid flow with a reaction front propagating through it such that the propagation does not affect the underlying flow. A reaction front might be chemical (Belousov-Zhabotinsky, flame front, etc.) or some other type of front (electromagnetic, acoustic, etc.). While the recently developed theory of burning invariant manifolds (BIMs) describes barriers to front propagation in time-periodic flows, this current work provides an important complement by extending to the aperiodic setting. Funded by NSF Grant CMMI-1201236.

  12. Thin front propagation in random shear flows.

    PubMed

    Chinappi, M; Cencini, M; Vulpiani, A

    2006-01-01

    Front propagation in time-dependent laminar flows is investigated in the limit of very fast reaction and very thin fronts--i.e., the so-called geometrical optics limit. In particular, we consider fronts stirred by random shear flows, whose time evolution is modeled in terms of Ornstein-Uhlembeck processes. We show that the ratio between the time correlation of the flow and an intrinsic time scale of the reaction dynamics (the wrinkling time tw) is crucial in determining both the front propagation speed and the front spatial patterns. The relevance of time correlation in realistic flows is briefly discussed in light of the bending phenomenon--i.e., the decrease of propagation speed observed at high flow intensities.

  13. The dynamics of oceanic fronts. I - The Gulf Stream

    NASA Technical Reports Server (NTRS)

    Kao, T. W.

    1980-01-01

    The establishment and maintenance of the mean hydrographic properties of large-scale density fronts in the upper ocean is considered. The dynamics is studied by posing an initial value problem starting with a near-surface discharge of buoyant water with a prescribed density deficit into an ambient stationary fluid of uniform density; full time dependent diffusion and Navier-Stokes equations are then used with constant eddy diffusion and viscosity coefficients, together with a constant Coriolis parameter. Scaling analysis reveals three independent scales of the problem including the radius of deformation of the inertial length, buoyancy length, and diffusive length scales. The governing equations are then suitably scaled and the resulting normalized equations are shown to depend on the Ekman number alone for problems of oceanic interest. It is concluded that the mean Gulf Stream dynamics can be interpreted in terms of a solution of the Navier-Stokes and diffusion equations, with the cross-stream circulation responsible for the maintenance of the front; this mechanism is suggested for the maintenance of the Gulf Stream dynamics.

  14. Performance through Deformation and Instability

    NASA Astrophysics Data System (ADS)

    Bertoldi, Katia

    2015-03-01

    Materials capable of undergoing large deformations like elastomers and gels are ubiquitous in daily life and nature. An exciting field of engineering is emerging that uses these compliant materials to design active devices, such as actuators, adaptive optical systems and self-regulating fluidics. Compliant structures may significantly change their architecture in response to diverse stimuli. When excessive deformation is applied, they may eventually become unstable. Traditionally, mechanical instabilities have been viewed as an inconvenience, with research focusing on how to avoid them. Here, I will demonstrate that these instabilities can be exploited to design materials with novel, switchable functionalities. The abrupt changes introduced into the architecture of soft materials by instabilities will be used to change their shape in a sudden, but controlled manner. Possible and exciting applications include materials with unusual properties such negative Poisson's ratio, phononic crystals with tunable low-frequency acoustic band gaps and reversible encapsulation systems.

  15. Deforming the hippocampal map.

    PubMed

    Touretzky, David S; Weisman, Wendy E; Fuhs, Mark C; Skaggs, William E; Fenton, Andre A; Muller, Robert U

    2005-01-01

    To investigate conjoint stimulus control over place cells, Fenton et al. (J Gen Physiol 116:191-209, 2000a) recorded while rats foraged in a cylinder with 45 degrees black and white cue cards on the wall. Card centers were 135 degrees apart. In probe trials, the cards were rotated together or apart by 25 degrees . Firing field centers shifted during these trials, stretching and shrinking the cognitive map. Fenton et al. (2000b) described this deformation with an ad hoc vector field equation. We consider what sorts of neural network mechanisms might be capable of accounting for their observations. In an abstract, maximum likelihood formulation, the rat's location is estimated by a conjoint probability density function of landmark positions. In an attractor neural network model, recurrent connections produce a bump of activity over a two-dimensional array of cells; the bump's position is influenced by landmark features such as distances or bearings. If features are chosen with appropriate care, the attractor network and maximum likelihood models yield similar results, in accord with previous demonstrations that recurrent neural networks can efficiently implement maximum likelihood computations (Pouget et al. Neural Comput 10:373-401, 1998; Deneve et al. Nat Neurosci 4:826-831, 2001). PMID:15390166

  16. Acoustic emission of coal in the postlimiting deformation state

    SciTech Connect

    Voznesenskii, A.S.; Tavostin, M.N.

    2005-08-01

    The features of acoustic emission in coal samples in the state of pre- and postlimiting deformation are considered. It is shown that in the postlimiting deformation stages and in the transient period, a contrary change is observed in a correlation coefficient of the acoustic emission activity N{Sigma} recorded in the upper and lower portions of a sample; whereas in the prelimiting deformation stages, this change is consistent. It is proposed to recognize the stages of deformation by the correlation coefficient of N{Sigma} recorded in different zones: a positive coefficient corresponds to the prelimiting stage of deformation, and a negative one corresponds to the postlimiting stage.

  17. [Correction of complex deformities in infectious conditions].

    PubMed

    Suger, G; Schmelz, A; Kinzl, L; Liener, U

    2000-01-01

    Skeletal deformities do occur after conservative or operative fracture treatment, as a consequence of congenital growth disturbance and as sequlae after posttraumatic and haematogenous osteomyelitis. In postinfectious deformities the course of the bone and soft tissue infection plays a decisive role when choosing the appropriate operative technique. Even in non active situations with a closed soft tissues envelope and no draining sinus persistence of germs within the bone has to be anticipated. The biological quality of the bone and the soft tissue envelope is often reduced because of local changes and as a result of multiple local revisions. Consequently wide areas of scar tissue and sclerotic bone are often encountered. The apex of the deformity is in most cases identical with the focus of the active or non active infection. The correction of the deformity at the apex can therefore only be accomplished if the infectious bone is also resected. If a correction is not possible at the apex of the deformity, translation at the osteotomy site is necessary to achieve a correct mechanical axis. The later rather complex operative procedure necessitates intensive preoperative planning and an extensive experience with deformity corrections by external fixators. PMID:10663242

  18. Dipolarization front and current disruption

    NASA Astrophysics Data System (ADS)

    Lui, A. T. Y.

    2016-10-01

    The modification of current density on the dawn-dusk cross section of the magnetotail with the earthward approach of a dipolarization front (DF) is examined through the recently published results of a three-dimensional (3-D) particle-in-cell (PIC) simulation. It is found that the current density intensifies by 37% abruptly within 1.5 ion gyrotime as the DF approaches and shows localized regions with north-south extrusions. After reaching its peak value, it undergoes a drastic current reduction (DCR) by 65% within 2 ion gyrotime. Breakdown of the frozen-in condition occurs in the neutral sheet region in association with DCR, demonstrating the non-MHD behavior of the phenomenon. The evolution of current density from this 3-D PIC simulation bears several similarities to those observed for the current disruption (CD) phenomenon, such as explosive growth and disruption of the current density leading to a breakdown of the frozen-in condition. The evolution is also similar to those from a previous two-dimensional (2-D) PIC simulation specially designed to investigate the nonlinear evolution of the cross-field current instability for CD. One interpretation of these findings is that CD and substorm triggering can be associated with earthward intrusion of a DF into the near-Earth plasma sheet as indicated by previous Cluster and Time History of Events and Macroscale Interactions during Substorms observations. An alternative interpretation is that both DF and CD are consequences of a global evolution from an ion-tearing-like instability of the magnetotail.

  19. Life on the front lines.

    PubMed

    Hern, W M

    1994-01-01

    Warren Hern's reminiscences about his experiences as medical director of the Boulder (Colorado) Abortion Clinic and as an abortion provider in private practice provide support for his statement, "Every doctor in America who does abortions lives under a death threat." Shortly after the clinic was opened, a group of anti-abortion physicians pressured the Boulder County Medical Society to pass a resolution declaring the clinic a "clear and present danger" that should be shut down by local health boards. As the only freestanding abortion clinic in the state in the mid-1970's, the Boulder center was targeted by the Right-to-Life Committee picketers and Dr. Hern was harassed in his home and in public. When Dr. Hern left the clinic a year later to establish a private practice specializing in pregnancy termination, the picketers followed. After release of a textbook he prepared on abortion practice, the publisher was deluged with hate mail and threats of boycott, leading them to withdraw the text from its list. Violent attacks on abortion clinics accelerated after Reagan's election and bullets were fired into Hern's waiting room. Randall Terry, national head of Operation Rescue, prayed for Hern's death at a rally in front of his clinic. By the time Dr. David Gunn was assassinated by an anti-abortionist in March 1993, there had been over 1285 acts of violence against abortion facilities and more than 100 facilities had been completely destroyed. The transgression for which Dr. Gunn was murdered was that he sought to save the lives and futures of countless women and support their right to become full participants in society.

  20. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    NASA Astrophysics Data System (ADS)

    Jørgen Kjøll, Hans; Viola, Giulio; Menegon, Luca; Sørensen, Bjørn

    2015-04-01

    A coarse grained, statically crystallized quartz vein with a random CPO, embedded in a phyllonitic matrix, was studied by optical microscopy, SEM imaging and EBSD to gain insights into the processes of strain localization in quartz deformed under low greenschist facies conditions at the frictional-viscous transition. The vein is located in a high strain zone at the front of an imbricate stack of Caledonian age along the northwesternmost edge of the Repparfjord Tectonic Window in northern Norway. The vein was deformed within the Nussirjavrri Fault Zone (NFZ), an out-of-sequence thrust with a phyllonitic core characterized by a ramp-flat-ramp geometry, NNW plunging stretching lineations and top-to-the SSE thrusting kinematics. Deformation conditions are typical of the frictional-viscous transition. The phyllonitic core formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation, related to the development of a mesoscopic pervasive extensional crenulation cleavage, was accommodated within the vein initially by basal slip of suitably oriented quartz crystals, which produced e.g. undulose extinction, extinction bands and bulging grain boundaries. In the case of misoriented quartz crystals, however, glide-accommodated dislocation creep resulted soon inefficient and led to localized dislocation tangling and strain hardening. In response to 1) hardening, 2) progressive increase of fluid pressure within the actively deforming vein and 3) increasing competence contrast between the vein and the surrounding weak, foliated phyllonitic fault core, quartz crystals began to deform frictionally along specific lattice planes oriented optimally with respect to the imposed stress field. Microfaulting generated small volumes of gouge along

  1. Cold Fronts in Cold Dark Matter Clusters

    NASA Astrophysics Data System (ADS)

    Nagai, Daisuke; Kravtsov, Andrey V.

    2003-04-01

    Recently, high-resolution Chandra observations revealed the existence of very sharp features in the X-ray surface brightness and temperature maps of several clusters. These features, called cold fronts, are characterized by an increase in surface brightness by a factor >~2 over 10-50 kpc accompanied by a drop in temperature of a similar magnitude. The existence of such sharp gradients can be used to put interesting constraints on the physics of the intracluster medium (ICM) if their mechanism and longevity are well understood. Here, we present results of a search for cold fronts in high-resolution simulations of galaxy clusters in cold dark matter models. We show that sharp gradients with properties similar to those of observed cold fronts naturally arise in cluster mergers when the shocks heat gas surrounding the merging subcluster, while its dense core remains relatively cold. The compression induced by supersonic motions and shock heating during the merger enhance the amplitude of gas density and temperature gradients across the front. Our results indicate that cold fronts are nonequilibrium transient phenomena and can be observed for a period of less than a billion years. We show that the velocity and density fields of gas surrounding the cold front can be very irregular, which would complicate analyses aiming to put constraints on the physical conditions of the ICM in the vicinity of the front.

  2. Principles of rock deformation

    SciTech Connect

    Nicolas, A.

    1987-01-01

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

  3. Problems and solutions for drawing fronts objectively

    NASA Astrophysics Data System (ADS)

    McCann, Donald W.; Whistler, James P.

    2001-06-01

    A recent requirement charged to the Aviation Weather Center (AWC) is to produce significant weather charts for aviation users with, among other forecast products, forecast locations of significant fronts. To increase forecaster productivity, the AWC decided to evaluate the possibility that fronts should be first drawn objectively. Hewson (1998) describes the basic technique which uses a variation on the Renard & Clarke (1965) frontal locator function to find the fronts. The AWC had to overcome many problems in implementing Hewson's techniques. This paper illuminates the problems and describes the AWC solutions. As a result of the AWC's success, objective frontal analyses and forecasts are now a reality, and the productivity of forecasters increased.

  4. Collisionless ion dynamics in the shock front

    NASA Astrophysics Data System (ADS)

    Gedalin, Michael

    2016-07-01

    In the vicinity of the shock front the dynamics of ions is governed by the macroscopic regular electric and magnetic field of the shock. Upon crossing the shock the thermal ions form a non-gyrotropic distribution. The pressure of these non-gyrotropic ions shapes the downstream magnetic field. High-energy ions behave in the shock front as test particles under the influence on the macroscopic fields. The reflection and transmission coefficients of high-energy ions at an oblique shock front is not sensitive to the shock structure and depends only on the global magnetic field change at the shock.

  5. Polygonal deformation bands

    NASA Astrophysics Data System (ADS)

    Antonellini, Marco; Mollema, Pauline Nella

    2015-12-01

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

  6. Polygonal deformation bands

    NASA Astrophysics Data System (ADS)

    Antonellini, Marco; Mollema, Pauline Nella

    2015-12-01

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

  7. Geomorphic analysis in areas of low-rate neotectonic deformation: South Epirus (Greece) as a case study

    NASA Astrophysics Data System (ADS)

    Ntokos, Dimitrios; Lykoudi, Evdoxia; Rondoyanni, Theodora

    2016-06-01

    River morphology and the distribution of river deposits reliably reflect the neotectonic activity of a region in relation to rock resistance and climatic changes. Geomorphic indices have been used to identify landscape evolution and active faults, particularly in areas of high-rate tectonic deformation. In areas of low-rate deformation, the influence of neotectonic activity on landscape evolution is less apparent, although it is important. The aim of this study is to examine the region of south Epirus (Greece), a region where the rates of active tectonic processes are low. Because rock resistance is low and the sediment supply is intense in this region, the fault surfaces are either not well preserved or they are covered. For the purposes of this paper, geomorphic analysis (including the drainage basin asymmetry factor, the basin hypsometric curve and integral, the valley floor width-to-height ratio, longitudinal river profiles, the stream-length gradient index normalized by the graded river gradient, and the mountain front sinuosity index) was used to evaluate neotectonic activity and to identify covered, potentially active faults. In places where fault surfaces could be observed, geological mapping and tectonic analysis were applied to determine the fault characteristics. The first result of this work is that important active or potentially active faults extend for a significant distance into the alluvial plains of south Epirus. In this case study, we considered that geomorphic indices constitute a valuable tool for identifying neotectonic activity in regions of low-rate deformation. Furthermore, geomorphic analysis reveals the location of covered fault structures, contributes to evaluating fault capability, and therefore to estimating seismotectonic hazard.

  8. Deformation of Alaskan Volcanoes, Measured by Satellite Radar Inferometry

    NASA Technical Reports Server (NTRS)

    Freymueller, Jeff; Dean, Ken; Wyss, Max

    1999-01-01

    The purpose of this project was to determine the suitability of measuring active deformation of volcanoes in Alaska using Interferometric Synthetic Aperture Radar (INSAR) techniques. Work sponsored by this grant supported one graduate student (for almost 2 years) and one postdoc (for several months), and has resulted in two published peer-reviewed papers and a front-page article in EOS. An additional paper is in review and a fourth is in preparation. An additional paper in preparation was based in part on research supported by this grant and in part by a successor grant from NASA's Solid Earth Natural Hazards program. Over the course of this research, we documented measurable uplift of Trident volcano in the Katmai group, conducted a systematic study of the change in phase coherence over time on volcanic surfaces, and measured and modeled the spectacular 1.5 m deflation of Okmok caldera associated with its 1997 eruption. We also generated initial interferograms spanning the 1996 seismic swarm of Akutan volcano; however, during the period covered by this project we were not able to remove topography. That has been done under the subsequent funding and a paper is now in preparation. This report summarizes work done under two separate contracts because both were based on the same proposal to NASA's ADRO (Application Development and Research Opportunity) program. The first year was funded out of a grant from NASA Headquarters and the second and third years out of a grant through Goddard. The work, however, was a continuous three year effort.

  9. Consumer preferences for front-of-pack calories labelling

    PubMed Central

    van Kleef, Ellen; van Trijp, Hans; Paeps, Frederic; Fernández-Celemín, Laura

    2008-01-01

    Objective In light of the emerging obesity pandemic, front-of-pack calories labels may be an important tool to assist consumers in making informed healthier food choices. However, there is little prior research to guide key decisions on whether caloric content should be expressed in absolute terms or relative to recommended daily intake, whether it should be expressed in per serving or per 100 g and whether the information should be further brought alive for consumers in terms of what the extra calorie intake implies in relation to activity levels. The present study aimed at providing more insight into consumers’ appreciation of front-of-pack labelling of caloric content of food products and their specific preferences for alternative execution formats for such information in Europe. Design For this purpose, eight executions of front-of-pack calorie flags were designed and their appeal and information value were extensively discussed with consumers through qualitative research in four different countries (Germany, The Netherlands, France and the UK). Results The results show that calories are well-understood and that participants were generally positive about front-of-pack flags, particularly when flags are uniform across products. The most liked flags are the simpler flags depicting only the number of calories per serving or per 100 g, while more complex flags including references to daily needs or exercise and the flag including a phrase referring to balanced lifestyle were least preferred. Some relevant differences between countries were observed. Although participants seem to be familiar with the notion of calories, they do not seem to fully understand how to apply them. Conclusion From the results, managerial implications for the design and implementation of front-of-pack calorie labelling as well as important directions for future research are discussed. PMID:17601362

  10. Heat conduction fronts in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Soker, Noam

    1994-01-01

    We present arguments which suggest that many of the x-ray, some optical, and some UV observations of planetary nebulae, can be explained by the presence of heat conduction fronts. The heat flows from the hot bubble formed by the shocked fast wind to the cool shell and halo. Heat conduction fronts are likely to account for emission of x rays from plasma at lower temperature than the expected temperature of the hot bubble. In the presence of magnetic fields, only a small fraction of the fast wind luminosity emerges as radiation. Heat conduction fronts can naturally produce some unusual line flux ratios, which are observed in some planetary nebulae. Heat conduction fronts may heat the halo and cause some material at the inner surface of the shell to expand slower than the rest of the shell. In the presence of an asymmetrical magnetic field, this flow, the x-ray intensity, and the emission lines, may acquire asymmetrical structure as well.

  11. Optimizing emergency department front-end operations.

    PubMed

    Wiler, Jennifer L; Gentle, Christopher; Halfpenny, James M; Heins, Alan; Mehrotra, Abhi; Mikhail, Michael G; Fite, Diana

    2010-02-01

    As administrators evaluate potential approaches to improve cost, quality, and throughput efficiencies in the emergency department (ED), "front-end" operations become an important area of focus. Interventions such as immediate bedding, bedside registration, advanced triage (triage-based care) protocols, physician/practitioner at triage, dedicated "fast track" service line, tracking systems and whiteboards, wireless communication devices, kiosk self check-in, and personal health record technology ("smart cards") have been offered as potential solutions to streamline the front-end processing of ED patients, which becomes crucial during periods of full capacity, crowding, and surges. Although each of these operational improvement strategies has been described in the lay literature, various reports exist in the academic literature about their effect on front-end operations. In this report, we present a review of the current body of academic literature, with the goal of identifying select high-impact front-end operational improvement solutions. PMID:19556030

  12. Leap Day 2012 Severe Storm Front

    NASA Video Gallery

    This movie was created using GOES-13 visible and infrared satellite imagery from Feb. 28 at 1245 UTC (7:45 a.m. EST) through March 1, and shows the progression of the cold front and associated low ...

  13. Front-End Analysis Cornerstone of Logistics

    NASA Technical Reports Server (NTRS)

    Nager, Paul J.

    2000-01-01

    The presentation provides an overview of Front-End Logistics Support Analysis (FELSA), when it should be performed, benefits of performing FELSA and why it should be performed, how it is conducted, and examples.

  14. Nonperturbative light-front Hamiltonian methods

    NASA Astrophysics Data System (ADS)

    Hiller, J. R.

    2016-09-01

    We examine the current state-of-the-art in nonperturbative calculations done with Hamiltonians constructed in light-front quantization of various field theories. The language of light-front quantization is introduced, and important (numerical) techniques, such as Pauli-Villars regularization, discrete light-cone quantization, basis light-front quantization, the light-front coupled-cluster method, the renormalization group procedure for effective particles, sector-dependent renormalization, and the Lanczos diagonalization method, are surveyed. Specific applications are discussed for quenched scalar Yukawa theory, ϕ4 theory, ordinary Yukawa theory, supersymmetric Yang-Mills theory, quantum electrodynamics, and quantum chromodynamics. The content should serve as an introduction to these methods for anyone interested in doing such calculations and as a rallying point for those who wish to solve quantum chromodynamics in terms of wave functions rather than random samplings of Euclidean field configurations.

  15. On the stability of subsonic thermal fronts

    SciTech Connect

    Ibanez S, Miguel H.; Shchekinov, Yuri; Bessega L, Maria C.

    2005-08-15

    The stability of subsonic thermal fronts against corrugation is analyzed and an exact dispersion relation is obtained taking into account the compressibility of the gas. For heat fronts, this dispersion equation has an unstable root ({omega}{sub ex}) corresponding to the Landau-Darrieus unstable mode ({omega}{sub 0}) modified by the compressional effects. In particular, the exact solution shows a conspicuous maximum very close to the value of the intake Mach number M{sub 1} at which a Chapman-Jouguet deflagration wave behind the heat front is formed. Cooling fronts are stable for corrugation-like disturbances. A maximum damping as well as a maximum in the frequency occur at a value of M{sub 1} depending on the value of the normalized cooling q.

  16. Reverse Kirner's deformity: case report.

    PubMed

    Lau, Yeong J; Tonkin, Michael A

    2009-03-01

    Kirner's deformity is a rare congenital deformity, usually of the little finger, with volar and radial bowing of the distal phalanx. The etiology of this deformity is unclear. We describe a case of a 9-year-old girl with radiographic changes classic for Kirner's deformity but with the curvature and nail changes in the dorsal direction.

  17. Propelling efficiency of front-crawl swimming.

    PubMed

    Toussaint, H M; Beelen, A; Rodenburg, A; Sargeant, A J; de Groot, G; Hollander, A P; van Ingen Schenau, G J

    1988-12-01

    In this study the propelling efficiency (ep) of front-crawl swimming, by use of the arms only, was calculated in four subjects. This is the ratio of the power used to overcome drag (Pd) to the total mechanical power (Po) produced including power wasted in changing the kinetic energy of masses of water (Pk). By the use of an extended version of the system to measure active drag (MAD system), Pd was measured directly. Simultaneous measurement of O2 uptake (VO2) enabled the establishment of the relationship between the rate of the energy expenditure (PVO2) and Po (since when swimming on the MAD system Po = Pd). These individual relationships describing the mechanical efficiency (8-12%) were then used to estimate Po in free swimming from measurements of VO2. Because Pd was directly measured at each velocity studied by use of the MAD system, ep could be calculated according to the equation ep = Pd/(Pd + Pk) = Pd/Po. For the four top class swimmers studied, ep was found to range from 46 to 77%. Total efficiency, defined as the product of mechanical and propelling efficiency, ranged from 5 to 8%. PMID:3215850

  18. Speed of pulled fronts with a cutoff.

    PubMed

    Benguria, R D; Depassier, M C

    2007-05-01

    We study the effect of a small cutoff epsilon on the velocity of a pulled front in one dimension by means of a variational principle. We obtain a lower bound on the speed dependent on the cutoff, for which the two leading order terms correspond to the Brunet-Derrida expression. To do so we cast a known variational principle for the speed of propagation of fronts in different variables which makes it more suitable for applications. PMID:17677021

  19. Does Your Front Desk Staff Maximize Collections?

    PubMed

    Weinstock, Donna

    2015-01-01

    As collections become more difficult, practices need to use the front desk to help collect payments from patients when they are face to face. Training staff and giving them the tools to ask for money allows them to collect efficiently. Improve your collections by involving your front desk employees. Educate your patients to allow them to come to their visits prepared. It will save the practice time and money. PMID:26399028

  20. Does Your Front Desk Staff Maximize Collections?

    PubMed

    Weinstock, Donna

    2015-01-01

    As collections become more difficult, practices need to use the front desk to help collect payments from patients when they are face to face. Training staff and giving them the tools to ask for money allows them to collect efficiently. Improve your collections by involving your front desk employees. Educate your patients to allow them to come to their visits prepared. It will save the practice time and money.

  1. Turbulent transport model of wind shear in thunderstorm gust fronts and warm fronts

    NASA Technical Reports Server (NTRS)

    Lewellen, W. S.; Teske, M. E.; Segur, H. C. O.

    1978-01-01

    A model of turbulent flow in the atmospheric boundary layer was used to simulate the low-level wind and turbulence profiles associated with both local thunderstorm gust fronts and synoptic-scale warm fronts. Dimensional analyses of both type fronts provided the physical scaling necessary to permit normalized simulations to represent fronts for any temperature jump. The sensitivity of the thunderstorm gust front to five different dimensionless parameters as well as a change from axisymmetric to planar geometry was examined. The sensitivity of the warm front to variations in the Rossby number was examined. Results of the simulations are discussed in terms of the conditions which lead to wind shears which are likely to be most hazardous for aircraft operations.

  2. Life on the front lines.

    PubMed

    Hern, W M

    1993-01-01

    honor those who advanced the cause of women's rights. They honored the physician who had to shout over hecklers to make his remarks heard. After a year of operation, the physician encountered differences with the Board of Directors of the clinic. Soon after that, he resigned and opened his own clinic with a bank loan of $7000. Within 4 years, his clinic had expanded, and he purchased its building. The harassment from antiabortion protesters continued, with broken windows, pickets, and, in February 1988, bullets fired through the front windows of the waiting room. This necessitated the installation of bullet-proof glass and a security system which cost $17,000. As of March 1, 1993, there had been 1285 acts of violence towards abortion clinics, which led to the destruction of more than 100. On March 10 of that year, a physician who performed abortions in Florida was gunned down by an anti-abortion protestor. People who provide abortions hope for legal protection and respect for their civil liberties, but they will continue to provide this service even if conditions do not improve.

  3. Two-deformable-mirror concept for correcting scintillation effects in laser beam projection through the turbulent atmosphere.

    PubMed

    Roggemann, M C; Lee, D J

    1998-07-20

    A two-deformable-mirror concept for correcting scintillation effects in laser beam projection through the turbulent atmosphere is presented. This system uses a deformable mirror and a Fourier-transforming mirror to adjust the amplitude of the wave front in the telescope pupil, similar to kinoforms used in laser beam shaping. A second deformable mirror is used to correct the phase of the wave front before it leaves the aperture. The phase applied to the deformable mirror used for controlling the beam amplitude is obtained with a technique based on the Fienup phase-retrieval algorithm. Simulations of propagation through a single turbulent layer sufficiently distant from the beacon observation and laser beam transmission aperture to cause scintillation shows that, for an ideal deformable-mirror system, this field-conjugation approach improves the on-axis field amplitude by a factor of approximately 1.4 to 1.5 compared with a conventional phase-only correction system.

  4. Interaction of a cold front with a sea-breeze front Numerical simulations

    NASA Astrophysics Data System (ADS)

    Rhodin, A.

    1995-08-01

    This paper presents simulations of a front which passed the coast between the North Sea and northern Germany and thereby experienced some modifications of its mesoscale characteristics. The event was observed during the field experiment FRONTEX'89. The two-dimensional non-hydrostatic simulations presented in this paper resemble some of the observed characteristics and yield a detailed description of the evolution of the surface front. Over the sea several narrow frontal rain bands develop in the boundary layer which becomes unstable due to the increasing sea surface temperature near the coast. The rain bands move forward relative to the front due to the cross frontal circulation which is enhanced by the release of latent heat in the ascending warm air and by the cooling of the cold air below by evaporating precipitation. Over the heated land surface a sea-breeze front develops ahead of the synoptic-scale cold front. The strong frontal gradients of the sea-breeze front mask the broader frontal zone of the cold front at the ground. The sea-breeze front triggers deep convection ahead of the cold front in the afternoon and takes over all characteristics of the synoptic-scale front in the evening. The simulations show the mechanisms that caused the observed evolution and modification of the synoptic-scale cold front. They emphasize the strong influence of the surface heat fluxes on the characteristics of fronts on the mesoscale. The most important feature of the numerical model, necessary for the proper representation of the frontal characteristics on the mesoscale, is its high resolution. The simulations are restricted by the difficulties of finding an initial state and appropriate boundary conditions so that the results fit the observations for a long time period and that spin-up problems are avoided.

  5. Triggered deformation and seismic activity under Mammoth Mountain in long Valley caldera by the 3 November 2002 Mw 7.9 Denali fault earthquake

    USGS Publications Warehouse

    Johnston, M.J.S.; Prejean, S.G.; Hill, D.P.

    2004-01-01

    The 3 November 2002 Mw 7.9 Denali fault earthquake triggered deformational offsets and microseismicity under Mammoth Mountain (MM) on the rim of Long Valley caldera, California, some 3460 km from the earthquake. Such strain offsets and microseismicity were not recorded at other borehole strain sites along the San Andreas fault system in California. The Long Valley offsets were recorded on borehole strainmeters at three sites around the western part of the caldera that includes Mammoth Mountain - a young volcano on the southwestern rim of the caldera. The largest recorded strain offsets were -0.1 microstrain at PO on the west side of MM, 0.05 microstrain at MX to the southeast of MM, and -0.025 microstrain at BS to the northeast of MM with negative strain extensional. High sample rate strain data show initial triggering of the offsets began at 22:30 UTC during the arrival of the first Rayleigh waves from the Alaskan earthquake with peak-to-peak dynamic strain amplitudes of about 2 microstrain corresponding to a stress amplitude of about 0.06 MPa. The strain offsets grew to their final values in the next 10 min. The associated triggered seismicity occurred beneath the south flank of MM and also began at 22:30 UTC and died away over the next 15 min. This relatively weak seismicity burst included some 60 small events with magnitude all less than M = 1. While poorly constrained, these strain observations are consistent with triggered slip and intrusive opening on a north-striking normal fault centered at a depth of 8 km with a moment of l016 N m, or the equivalent of a M 4.3 earthquake. The cumulative seismic moment for the associated seismicity burst was more than three orders of magnitude smaller. These observations and this model resemble those for the triggered deformation and slip that occurred beneath the north side of MM following the 16 October 1999 M 7.1 Hector Mine, California, earthquake. However, in this case, we see little post-event slip decay reflected in

  6. Formation Flying and Deformable Instruments

    SciTech Connect

    Rio, Yvon

    2009-05-11

    Astronomers have always attempted to build very stable instruments. They fight all that can cause mechanical deformation or image motion. This has led to well established technologies (autoguide, active optics, thermal control, tip/tilt correction), as well as observing methods based on the use of controlled motion (scanning, micro scanning, shift and add, chopping and nodding). Formation flying disturbs this practice. It is neither possible to reduce the relative motion to very small amplitudes, nor to control it at will. Some impacts on Simbol-X instrument design, and operation are presented.

  7. Formation Flying and Deformable Instruments

    NASA Astrophysics Data System (ADS)

    Rio, Yvon

    2009-05-01

    Astronomers have always attempted to build very stable instruments. They fight all that can cause mechanical deformation or image motion. This has led to well established technologies (autoguide, active optics, thermal control, tip/tilt correction), as well as observing methods based on the use of controlled motion (scanning, micro scanning, shift and add, chopping and nodding). Formation flying disturbs this practice. It is neither possible to reduce the relative motion to very small amplitudes, nor to control it at will. Some impacts on Simbol-X instrument design, and operation are presented.

  8. COLD FRONTS AND GAS SLOSHING IN GALAXY CLUSTERS WITH ANISOTROPIC THERMAL CONDUCTION

    SciTech Connect

    ZuHone, J. A.; Markevitch, M.; Lee, D.

    2013-01-10

    Cold fronts in cluster cool cores should be erased on short timescales by thermal conduction, unless protected by magnetic fields that are 'draped' parallel to the front surfaces, suppressing conduction perpendicular to the sloshing fronts. We present a series of MHD simulations of cold front formation in the core of a galaxy cluster with anisotropic thermal conduction, exploring a parameter space of conduction strengths parallel and perpendicular to the field lines. Including conduction has a strong effect on the temperature distribution of the core and the appearance of the cold fronts. Though magnetic field lines are draping parallel to the front surfaces, preventing conduction directly across them, the temperature jumps across the fronts are nevertheless reduced. The geometry of the field is such that the cold gas below the front surfaces can be connected to hotter regions outside via field lines along directions perpendicular to the plane of the sloshing motions and along sections of the front that are not perfectly draped. This results in the heating of this gas below the front on a timescale of a Gyr, but the sharpness of the density and temperature jumps may nevertheless be preserved. By modifying the gas density distribution below the front, conduction may indirectly aid in suppressing Kelvin-Helmholtz instabilities. If conduction along the field lines is unsuppressed, we find that the characteristic sharp jumps seen in Chandra observations of cold front clusters do not form. Therefore, the presence of cold fronts in hot clusters is in contradiction with our simulations with full Spitzer conduction. This suggests that the presence of cold fronts in hot clusters could be used to place upper limits on conduction in the bulk of the intracluster medium. Finally, the combination of sloshing and anisotropic thermal conduction can result in a larger flux of heat to the core than either process in isolation. While still not sufficient to prevent a cooling

  9. Interfacial Bubble Deformations

    NASA Astrophysics Data System (ADS)

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

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

  10. Crustal deformation and earthquakes

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1984-01-01

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

  11. Marine fronts are important fishing areas for demersal species at the Argentine Sea (Southwest Atlantic Ocean)

    NASA Astrophysics Data System (ADS)

    Alemany, Daniela; Acha, Eduardo M.; Iribarne, Oscar O.

    2014-03-01

    The high primary and secondary production associated with frontal systems attract a diversity of organisms due to high prey availability; this is why a strong relationship between fronts and pelagic fisheries has been shown worldwide. In the Argentine Sea, demersal resources are the most important, both in economical and in ecological sense; so we hypothesize that fronts are also preferred fishing areas for demersal resources. We evaluated the relationship between spatial distribution of fishing effort and oceanographic fronts, analyzing three of the most important frontal systems located in the Argentine Sea: the shelf-break front, the southern Patagonia front and the mid-shelf front. Individual vessel satellite monitoring system data (VMS; grouped by fleet type: ice-trawlers, freezer-trawlers and jigging fleet) were studied and fishing events were identified. Fishing events per area were used as a proxy of fishing effort and its spatial distribution by fleet type was visualized and analyzed with Geographic Information Systems. Oceanographic fronts were defined using polygons based on satellite chlorophyll amplitude values, and the percentage of fishing events within each polygon was calculated. Results showed a positive association between fronts and fishing activities of the different fleets, which suggests the aggregation of target species in these zones. The coupling of the freezer-trawler and jigging fleets (that operate on lower trophic level species; Macruronus magellanicus and Illex argentinus respectively) with fronts was higher than the ice-trawler fleet, targeting species of higher trophic level (Merluccius hubbsi). Marine fronts represent important fishing areas, even for demersal resources, as the distribution of fishing fleets and fishing effort are positively associated with frontal zones.

  12. Deformation Survey of Volcanoes in Central America Using Japanese L-Band SAR Satellite ALOS-1

    NASA Astrophysics Data System (ADS)

    Amelug, F.; Lebowitz, J.

    2015-12-01

    The Japanese L-Band SAR satellite ALOS-1 has proven intself to be a useful tool for deformation monitoring of active volcanoes. Here we present a systematic deformation survey of volcanoes in Central America for the 2007-2011 time frame using the Small Baseline InSAR time-series approach. We present results for deforming volcanoes and non-deforming volcanoes, including simple elastic source models for the volcanoes that show surface deformation.

  13. Laser supported solid state absorption fronts in silica

    SciTech Connect

    Carr, C W; Bude, J D

    2010-02-09

    We develop a model based on simulation and experiment that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm{sup 2}) laser exposure. We find that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. This behavior is driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. The regime of parameter space critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

  14. Plate motion and deformation

    SciTech Connect

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

    1991-02-01

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

  15. Membranotropic photobiomodulation on red blood cell deformability

    NASA Astrophysics Data System (ADS)

    Luo, Gang-Yue; Zhao, Yan-Ping; Liu, Timon C.; Liu, Song-Hao

    2007-05-01

    To assess modulation of laser on erythrocyte permeability and deformability via cell morphology changes, healthy human echinocytes with shrinking size and high plasmic viscosity due to cellular dehydration were treated with 1 mW, 2 mW, 3 mW, and 5 mW laser power exposure respectively. Image analyzing system on single intact erythrocyte was applied for measuring comprehensive cell morphological parameters (surface area, external membrane perimeter, circle index and elongation index) that were determined by the modulation of erythrocyte water permeability and deformability to detect relationship between erythrocyte water permeability alteration and deformability. Our preliminary experiment showed that exposure under light dose of 5 mW for 5 min could induce more active erythrocyte swelling and deformation. water channel aquaporin-1(AQP-1) was inhibited by the incubation of HgCl II in the presence and absence of 5 mW laser irradiation. The result suggested that osmotic water permeability is a primary factor in the procedure of erythrocyte deformability. In addition, no modulation of laser(5mW) on erythrocyte deformability had been found when the echinocytes were cultured with GDP-β-S (G protein inhibitor).

  16. Preliminary deformation model for National Seismic Hazard map of Indonesia

    NASA Astrophysics Data System (ADS)

    Meilano, Irwan; Susilo, Gunawan, Endra; Sarsito, Dina; Prijatna, Kosasih; Abidin, Hasanuddin Z.; Efendi, Joni

    2015-04-01

    Preliminary deformation model for the Indonesia's National Seismic Hazard (NSH) map is constructed as the block rotation and strain accumulation function at the elastic half-space. Deformation due to rigid body motion is estimated by rotating six tectonic blocks in Indonesia. The interseismic deformation due to subduction is estimated by assuming coupling on subduction interface while deformation at active fault is calculated by assuming each of the fault`s segment slips beneath a locking depth or in combination with creeping in a shallower part. This research shows that rigid body motion dominates the deformation pattern with magnitude more than 15 mm/year, except in the narrow area near subduction zones and active faults where significant deformation reach to 25 mm/year.

  17. Preliminary deformation model for National Seismic Hazard map of Indonesia

    SciTech Connect

    Meilano, Irwan; Gunawan, Endra; Sarsito, Dina; Prijatna, Kosasih; Abidin, Hasanuddin Z.; Susilo,; Efendi, Joni

    2015-04-24

    Preliminary deformation model for the Indonesia’s National Seismic Hazard (NSH) map is constructed as the block rotation and strain accumulation function at the elastic half-space. Deformation due to rigid body motion is estimated by rotating six tectonic blocks in Indonesia. The interseismic deformation due to subduction is estimated by assuming coupling on subduction interface while deformation at active fault is calculated by assuming each of the fault‘s segment slips beneath a locking depth or in combination with creeping in a shallower part. This research shows that rigid body motion dominates the deformation pattern with magnitude more than 15 mm/year, except in the narrow area near subduction zones and active faults where significant deformation reach to 25 mm/year.

  18. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2010-04-06

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

  19. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2009-04-14

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

  20. Deformed Quantum Statistics

    NASA Astrophysics Data System (ADS)

    Inomata, Akira

    1997-03-01

    To understand possible physical consequences of quantum deformation, we investigate statistical behaviors of a quon gas. The quon is an object which obeys the minimally deformed commutator (or q-mutator): a a† - q a†a=1 with -1≤ q≤ 1. Although q=1 and q=-1 appear to correspond respectively to boson and fermion statistics, it is not easy to create a gas which unifies the boson gas and the fermion gas. We present a model which is able to interpolates between the two limits. The quon gas shows the Bose-Einstein condensation near the Boson limit in two dimensions.

  1. Lobster claw deformity.

    PubMed

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

    2014-01-01

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

  2. Lobster claw deformity.

    PubMed

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

    2014-01-01

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

  3. Pareto Fronts in Clinical Practice for Pinnacle

    SciTech Connect

    Janssen, Tomas; Kesteren, Zdenko van; Franssen, Gijs; Damen, Eugène; Vliet, Corine van

    2013-03-01

    Purpose: Our aim was to develop a framework to objectively perform treatment planning studies using Pareto fronts. The Pareto front represents all optimal possible tradeoffs among several conflicting criteria and is an ideal tool with which to study the possibilities of a given treatment technique. The framework should require minimal user interaction and should resemble and be applicable to daily clinical practice. Methods and Materials: To generate the Pareto fronts, we used the native scripting language of Pinnacle{sup 3} (Philips Healthcare, Andover, MA). The framework generates thousands of plans automatically from which the Pareto front is generated. As an example, the framework is applied to compare intensity modulated radiation therapy (IMRT) with volumetric modulated arc therapy (VMAT) for prostate cancer patients. For each patient and each technique, 3000 plans are generated, resulting in a total of 60,000 plans. The comparison is based on 5-dimensional Pareto fronts. Results: Generating 3000 plans for 10 patients in parallel requires on average 96 h for IMRT and 483 hours for VMAT. Using VMAT, compared to IMRT, the maximum dose of the boost PTV was reduced by 0.4 Gy (P=.074), the mean dose in the anal sphincter by 1.6 Gy (P=.055), the conformity index of the 95% isodose (CI{sub 95%}) by 0.02 (P=.005), and the rectal wall V{sub 65} {sub Gy} by 1.1% (P=.008). Conclusions: We showed the feasibility of automatically generating Pareto fronts with Pinnacle{sup 3}. Pareto fronts provide a valuable tool for performing objective comparative treatment planning studies. We compared VMAT with IMRT in prostate patients and found VMAT had a dosimetric advantage over IMRT.

  4. QCD and Light-Front Dynamics

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy F.; /SLAC /Southern Denmark U., CP3-Origins /Costa Rica U.

    2011-01-10

    AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its {beta}-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

  5. Light-Front Holography and the Light-Front Schrodinger Equation

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy

    2012-08-15

    One of the most important nonperturbative methods for solving QCD is quantization at fixed light-front time {tau} = t+z=c - Dirac's 'Front Form'. The eigenvalues of the light-front QCD Hamiltonian predict the hadron spectrum and the eigensolutions provide the light-front wavefunctions which describe hadron structure. More generally, we show that the valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schrodinger equation, with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. We outline a method for computing the required potential from first principles in QCD. The holographic mapping of gravity in AdS space to QCD, quantized at fixed light-front time, yields the same light front Schrodinger equation; in fact, the soft-wall AdS/QCD approach provides a model for the light-front potential which is color-confining and reproduces well the light-hadron spectrum. One also derives via light-front holography a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. The elastic and transition form factors of the pion and the nucleons are found to be well described in this framework. The light-front AdS/QCD holographic approach thus gives a frame-independent first approximation of the color-confining dynamics, spectroscopy, and excitation spectra of relativistic light-quark bound states in QCD.

  6. Concept for a laser guide beacon Shack-Hartmann wave-front sensor with dynamically steered subapertures.

    PubMed

    Baranec, Christoph J; Bauman, Brian J; Lloyd-Hart, Michael

    2005-04-01

    We describe an innovative implementation of the Shack-Hartmann wave-front sensor that is designed to correct the perspective elongation of a laser guide beacon in adaptive optics. Subapertures are defined by the segments of a deformable mirror rather than by a conventional lenslet array. A bias tilt on each segment separates the beacon images on the sensor's detector. One removes the perspective elongation by dynamically driving each segment with a predetermined open-loop signal that would, in the absence of atmospheric wave-front aberration, keep the corresponding beacon image centered on the subaperture's optical axis.

  7. Kinetics of Deformation of Alloys by Pulsed Pressure of an Electric Discharge

    NASA Astrophysics Data System (ADS)

    Chebotnyagin, L. M.; Potapov, V. V.; Lopatin, V. V.

    2015-05-01

    Stepped kinetics of deformation of alloys by pulsed pressure from an expanding plasma channel has been observed. On the deformation curves there are time intervals during which deformation does not vary, and these intervals shorten closer to the central cross sections of the wave source. This is explained by the shockwave nature of pressure transfer. A connection between the parameters of the discharge circuit and the pulsed pressure at the wave front of the expanding plasma channel is established enabling a quantitative estimate with allowance for the dynamic viscosity of the metal.

  8. Oblique-slip sedimentation and deformation in Nonacho basin (early Proterozoic), Northwest Territories, Canada

    SciTech Connect

    Aspler, L.B.; Donaldson, J.A.

    1984-04-01

    The Nonacho basin shares several traits with molassoid basins formed in oblique-slip settings: great thickness (about 9 km, 6 mi) of siliciclastic sediments deposited in alluvial fan, fan-delta, braided stream, beach, deltaic, and lacustrine environments; synsedimentary faults which activated nearby sources; rapid sedimentation and subsidence; telescoped facies transitions, particularly adjacent to active faults; extremely variable thickness of lithostratigraphic units; diachronous sedimentation resulting from the migration of source areas and sites of sedimentation along deformation fronts; mobility of deposition and deformation such that early sediments were uplifted, cannibalized, and redeposited; paleocurrents directed basinward near basin margins, and longitudinally in axial regions; lower greenschist facies metamorphism; paucity of volcanic rocks; and complicated structural geometries. However, these features alone are not diagnostic of qbique slip origin; all are compatible with rift, aulacogen, impactogen, retroarc, peripheral, intramontane, and broken foreland settings. More reliable indicators or an oblique-slip tectonic setting for the Nonacho basin are: anastomosing pattern of near-vertical, en echelon faults which delineate rhomb-, wedge, and rectangular-shaped semi-independent subbasins and basement uplifts; stretching lineations of shallow to moderate plunge along shear zones; folds and near-vertical penetrative fabrics, related to shear zones, but at angles of 20/sup 0/-30/sup 0/ to these zones. The Nonacho basin fill is interpreted as a foreland molasse of the Trans-Hudson orogene. Deposition and deformation probably occurred in response to convergence accommodated by oblique slip, analogous to the Tarim and Tsaidam basins of China, which developed in the late stages of India-Eurasia collision, north of the Tibetan Plateau.

  9. Front-end electronics for the LZ experiment

    NASA Astrophysics Data System (ADS)

    Morad, James; LZ Collaboration

    2016-03-01

    LZ is a second generation direct dark matter detection experiment with 5.6 tonnes of liquid xenon active target, which will be instrumented as a two-phase time projection chamber (TPC). The peripheral xenon outside the active TPC (``skin'') will also be instrumented. In addition, there will be a liquid scintillator based outer veto surrounding the main cryostat. All of these systems will be read out using photomultiplier tubes. I will present the designs for front-end electronics for all these systems, which have been optimized for shaping times, gains, and low noise. Preliminary results from prototype boards will also be presented.

  10. Light-Front Quantization of Gauge Theories

    SciTech Connect

    Brodskey, Stanley

    2002-12-01

    Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.

  11. MEMS Actuated Deformable Mirror

    SciTech Connect

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

    2005-11-10

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

  12. Transfer involving deformed nuclei

    SciTech Connect

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

    1985-03-01

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

  13. View of McKenzieRichey garage showing front opening, the false front, ...

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

    View of McKenzie-Richey garage showing front opening, the false front, metal roofing and horizontal plank siding, facing northeast - McKenzie Property, Garage, North Bank of Sailor Gulch, 750 feet northwest of intersection of U.S.F.S. Roads 651 & 349, Placerville, Boise County, ID

  14. Elasticity of adherent active cells on a compliant substrate

    NASA Astrophysics Data System (ADS)

    Banerjee, Shiladitya; Mertz, Aaron F.; Dufresne, Eric R.; Marchetti, M. Cristina

    2012-02-01

    We present a continuum mechanical model of rigidity sensing by livings cells adhering to a compliant substrate. The cell or cell colony is modeled as an elastic active gel, adapting recently developed continuum theories of active viscoelastic fluids. The coupling to the substrate enters as a boundary condition that relates the cell's deformation field to local stress gradients. In the presence of activity, the substrate induces spatially inhomogeneous contractile stresses and deformations, with a power law dependence of the total traction forces on cell or colony size. This is in agreement with recent experiments on keratinocyte colonies adhered to fibronectin coated surfaces. In the presence of acto-myosin activity, the substrate also enhances the cell polarization, breaking the cell's front-rear symmetry. Maximal polarization is observed when the substrate stiffness matches that of the cell, in agreement with experiments on stem cells.

  15. Grain-resolved analysis of localized deformation in nickel-titanium wire under tensile load.

    PubMed

    Sedmák, P; Pilch, J; Heller, L; Kopeček, J; Wright, J; Sedlák, P; Frost, M; Šittner, P

    2016-08-01

    The stress-induced martensitic transformation in tensioned nickel-titanium shape-memory alloys proceeds by propagation of macroscopic fronts of localized deformation. We used three-dimensional synchrotron x-ray diffraction to image at micrometer-scale resolution the grain-resolved elastic strains and stresses in austenite around one such front in a prestrained nickel-titanium wire. We found that the local stresses in austenite grains are modified ahead of the nose cone-shaped buried interface where the martensitic transformation begins. Elevated shear stresses at the cone interface explain why the martensitic transformation proceeds in a localized manner. We established the crossover from stresses in individual grains to a continuum macroscopic internal stress field in the wire and rationalized the experimentally observed internal stress field and the topology of the macroscopic front by means of finite element simulations of the localized deformation. PMID:27493178

  16. Grain-resolved analysis of localized deformation in nickel-titanium wire under tensile load

    NASA Astrophysics Data System (ADS)

    Sedmák, P.; Pilch, J.; Heller, L.; Kopeček, J.; Wright, J.; Sedlák, P.; Frost, M.; Šittner, P.

    2016-08-01

    The stress-induced martensitic transformation in tensioned nickel-titanium shape-memory alloys proceeds by propagation of macroscopic fronts of localized deformation. We used three-dimensional synchrotron x-ray diffraction to image at micrometer-scale resolution the grain-resolved elastic strains and stresses in austenite around one such front in a prestrained nickel-titanium wire. We found that the local stresses in austenite grains are modified ahead of the nose cone-shaped buried interface where the martensitic transformation begins. Elevated shear stresses at the cone interface explain why the martensitic transformation proceeds in a localized manner. We established the crossover from stresses in individual grains to a continuum macroscopic internal stress field in the wire and rationalized the experimentally observed internal stress field and the topology of the macroscopic front by means of finite element simulations of the localized deformation.

  17. Active thrusting within the Himalayan orogenic wedge in the Kashmir Himalayas

    NASA Astrophysics Data System (ADS)

    Gavillot, Y.

    2011-12-01

    Numerous lines of evidence indicate that significant distributed deformation occurs within the Himalayan fold-thrust belt. Active thrust faults lie as much as 100 km north of the active thrust front. Whereas geochemical and topographical data provide circumstantial evidence for internal deformation in Nepal, new mapping demonstrates that an active emergent thrust fault system extends stepwise from the Balakot-Bagh fault (source of the Mw 7.6 2005 Kashmir earthquake in Pakistan) more than 200 km to the southeast on the Riasi fault (RT). The RT with a fault length of ~70 km, is a ~50° northeast-dipping reverse fault system, which sits ~40 km north of the deformation front in the Kashmiri Himalaya of northwest India. Our mapping demonstrates that the Riasi thrust consists of two strands. The northern strand, Main Riasi thrust (MRT) strand, places Precambrian Sirban Limestone on folded unconsolidated (Pleistocene?) conglomerates. Undeformed younger alluvial deposits (Holocene?) overlyie the MRT, which implies no Holocene (?) surface rupture on this strand. To the south, the surface expression of the Riasi frontal thrust (RFT) includes a fault scarp and offset ~10 ka terrace deposits dated with 36CL depth profiles. OSL and 10Be depth profile dating indicate an age range between ~80 ka to ~30 ka for the Bidda terrace in the upper plate of the MRT, yielding estimates of long-term uplift rate of 5.0 ± 2.2 mm/yr, slip rate of 6.4 ± 2.9 mm/yr, and shortening rate of 4.1 ± 1.9mm/yr. Given a ~34 mm/yr India-Asia convergence rate in the NW Himalaya, our results indicate that internal deformation within the orogenic belt accounts for at least ~10% of the total India-Eurasia plate convergence, with remaining shortening absorbed mainly at the deformation front.

  18. Friction forces on phase transition fronts

    SciTech Connect

    Mégevand, Ariel

    2013-07-01

    In cosmological first-order phase transitions, the microscopic interaction of the phase transition fronts with non-equilibrium plasma particles manifests itself macroscopically as friction forces. In general, it is a nontrivial problem to compute these forces, and only two limits have been studied, namely, that of very slow walls and, more recently, ultra-relativistic walls which run away. In this paper we consider ultra-relativistic velocities and show that stationary solutions still exist when the parameters allow the existence of runaway walls. Hence, we discuss the necessary and sufficient conditions for the fronts to actually run away. We also propose a phenomenological model for the friction, which interpolates between the non-relativistic and ultra-relativistic values. Thus, the friction depends on two friction coefficients which can be calculated for specific models. We then study the velocity of phase transition fronts as a function of the friction parameters, the thermodynamic parameters, and the amount of supercooling.

  19. Optimal back-to-front airplane boarding.

    PubMed

    Bachmat, Eitan; Khachaturov, Vassilii; Kuperman, Ran

    2013-06-01

    The problem of finding an optimal back-to-front airplane boarding policy is explored, using a mathematical model that is related to the 1+1 polynuclear growth model with concave boundary conditions and to causal sets in gravity. We study all airplane configurations and boarding group sizes. Optimal boarding policies for various airplane configurations are presented. Detailed calculations are provided along with simulations that support the main conclusions of the theory. We show that the effectiveness of back-to-front policies undergoes a phase transition when passing from lightly congested airplanes to heavily congested airplanes. The phase transition also affects the nature of the optimal or near-optimal policies. Under what we consider to be realistic conditions, optimal back-to-front policies lead to a modest 8-12% improvement in boarding time over random (no policy) boarding, using two boarding groups. Having more than two groups is not effective. PMID:23848727

  20. Foam front propagation in anisotropic oil reservoirs.

    PubMed

    Grassia, P; Torres-Ulloa, C; Berres, S; Mas-Hernández, E; Shokri, N

    2016-04-01

    The pressure-driven growth model is considered, describing the motion of a foam front through an oil reservoir during foam improved oil recovery, foam being formed as gas advances into an initially liquid-filled reservoir. In the model, the foam front is represented by a set of so-called "material points" that track the advance of gas into the liquid-filled region. According to the model, the shape of the foam front is prone to develop concave sharply curved concavities, where the orientation of the front changes rapidly over a small spatial distance: these are referred to as "concave corners". These concave corners need to be propagated differently from the material points on the foam front itself. Typically the corner must move faster than those material points, otherwise spurious numerical artifacts develop in the computed shape of the front. A propagation rule or "speed up" rule is derived for the concave corners, which is shown to be sensitive to the level of anisotropy in the permeability of the reservoir and also sensitive to the orientation of the corners themselves. In particular if a corner in an anisotropic reservoir were to be propagated according to an isotropic speed up rule, this might not be sufficient to suppress spurious numerical artifacts, at least for certain orientations of the corner. On the other hand, systems that are both heterogeneous and anisotropic tend to be well behaved numerically, regardless of whether one uses the isotropic or anisotropic speed up rule for corners. This comes about because, in the heterogeneous and anisotropic case, the orientation of the corner is such that the "correct" anisotropic speed is just very slightly less than the "incorrect" isotropic one. The anisotropic rule does however manage to keep the corner very slightly sharper than the isotropic rule does.

  1. Foam front propagation in anisotropic oil reservoirs.

    PubMed

    Grassia, P; Torres-Ulloa, C; Berres, S; Mas-Hernández, E; Shokri, N

    2016-04-01

    The pressure-driven growth model is considered, describing the motion of a foam front through an oil reservoir during foam improved oil recovery, foam being formed as gas advances into an initially liquid-filled reservoir. In the model, the foam front is represented by a set of so-called "material points" that track the advance of gas into the liquid-filled region. According to the model, the shape of the foam front is prone to develop concave sharply curved concavities, where the orientation of the front changes rapidly over a small spatial distance: these are referred to as "concave corners". These concave corners need to be propagated differently from the material points on the foam front itself. Typically the corner must move faster than those material points, otherwise spurious numerical artifacts develop in the computed shape of the front. A propagation rule or "speed up" rule is derived for the concave corners, which is shown to be sensitive to the level of anisotropy in the permeability of the reservoir and also sensitive to the orientation of the corners themselves. In particular if a corner in an anisotropic reservoir were to be propagated according to an isotropic speed up rule, this might not be sufficient to suppress spurious numerical artifacts, at least for certain orientations of the corner. On the other hand, systems that are both heterogeneous and anisotropic tend to be well behaved numerically, regardless of whether one uses the isotropic or anisotropic speed up rule for corners. This comes about because, in the heterogeneous and anisotropic case, the orientation of the corner is such that the "correct" anisotropic speed is just very slightly less than the "incorrect" isotropic one. The anisotropic rule does however manage to keep the corner very slightly sharper than the isotropic rule does. PMID:27090239

  2. q-Deformed and c-Deformed Harmonic Oscillators

    NASA Astrophysics Data System (ADS)

    Sogami, I. S.; Koizumi, K.; Mir-Kasimov, R. M.

    2003-10-01

    Hamilton functions of classical deformed oscillators (c-deformed oscillators) are derived from Hamiltonians of q-deformed oscillators of the Macfarlane and Dubna types. A new scale parameter, lq, with the dimension of length, is introduced to relate a dimensionless parameter characterizing the deformation with the natural length of the harmonic oscillator. Contraction from q-deformed oscillators to c-deformed oscillators is accomplished by keeping lq finite while taking the limit hbar → 0. The c-deformed Hamilton functions for both types of oscillators are found to be invariant under discrete translations: the step of the translation for the Dubna oscillator is half of that for the Macfarlane oscillator. The c-deformed oscillator of the Macfarlane type has propagating solutions in addition to localized ones. Reinvestigation of the q-deformed oscillator carried out in the light of these findings for the c-deformed systems proves that the q-deformed systems are invariant under the same translation symmetries as the c-deformed systems and have propagating waves of the Bloch type.

  3. Front variability and surface ocean features of the presumed southern bluefin tuna spawning grounds in the tropical southeast Indian Ocean

    NASA Astrophysics Data System (ADS)

    Nieblas, Anne-Elise; Demarcq, Hervé; Drushka, Kyla; Sloyan, Bernadette; Bonhommeau, Sylvain

    2014-09-01

    The southern bluefin tuna (SBT, Thunnus maccoyii) is an ecologically and economically valuable fish. However, surprisingly little is known about its critical early life history, a period when mortality is several orders of magnitude higher than at any other life stage, and when larvae are highly sensitive to environmental conditions. Ocean fronts can be important in creating favourable spawning conditions, as they are a convergence of water masses with different properties that can concentrate planktonic particles and lead to enhanced productivity. In this study, we examine the front activity within the only region where SBT have been observed to spawn: the tropical southeast Indian Ocean between Indonesia and Australia (10°S-20°S, 105°E-125°E). We investigate front activity and its relationship to ocean dynamics and surface features of the region. Results are also presented for the entire Indian Ocean (30°N-45°S, 20°E-140°E) to provide a background context. We use an extension of the Cayula and Cornillon algorithm to detect ocean fronts from satellite images of sea surface temperature (SST) and chlorophyll-a concentration (chl-a). Front occurrence represents the probability of occurrence of a front at each pixel of an image. Front intensity represents the magnitude of the difference between the two water masses that make up a front. Relative to the rest of the Indian Ocean, both SST and chl-a fronts in the offshore spawning region are persistent in occurrence and weak in intensity. Front occurrence and intensity along the Australian coast are high, with persistent and intense fronts found along the northwest and west coasts. Fronts in the tropical southeast Indian Ocean are shown to have strong annual variability and some moderate interannual variability. SST front occurrence is found to lead the Southern Oscillation Index by one year, potentially linked to warming and wind anomalies in the Indian Ocean. The surface ocean characteristics of the offshore

  4. Light-front nuclear shell-model

    SciTech Connect

    Johnson, M.B.

    1990-01-01

    I examine the effects of nuclear structure on high-energy, high-momentum transfer processes, specifically the EMC effect. For pedagogical reasons, a fictitious but simple two-body system consisting of two equal-mass particles interacting in a harmonic oscillator potential has been chosen. For this toy nucleus, I utilize a widely-used link between instant-form and light-front dynamics, formulating nuclear structure and deep-inelastic scattering consistently in the laboratory system. Binding effects are compared within conventional instant-form and light-front dynamical frameworks, with appreciable differences being found in the two cases. 20 refs.

  5. Grain-scale processes in actively deforming magma mushes: New insights from electron backscatter diffraction (EBSD) analysis of biotite schlieren in the Jizera granite, Bohemian Massif

    NASA Astrophysics Data System (ADS)

    Žák, Jiří; Verner, Kryštof; Týcová, Patricie

    2008-12-01

    In the porphyritic Jizera granite, Bohemian Massif, three distinct types of lattice-preferred orientations of biotite grains were revealed in schlieren-delineated magmatic structures using the electron backscatter diffraction (EBSD) method. (1) Biotite basal planes (001) reorient from schlieren-subparallel near the schlieren base to schlieren-perpendicular in the upper part of the schlieren. Both orientations share subhorizontal ˜N-S to ˜NNE-SSW-trending a axes. (2) In some domains, the a axes are steep and at a high angle to the schlieren plane while the c axes plunge shallowly and rotate around an ill-defined a axis. (3) In other domains, the EBSD coincides with background magnetic fabric of the host granite revealed using the anisotropy of magnetic susceptibility (AMS) method: that is, the a axes plunge shallowly to the SE or NW while the c axes are subhorizontal and cluster around the ˜NE-SW trend. These multiple biotite orientations in the schlieren are interpreted to reflect (1) velocity-gradient in laminar magma flow along channel-like conduits, localized within the high-strength host phenocryst framework, (2) grain-scale gravity-driven constrictional deformation of the magma mush, and (3) overprinting background (tectonic?) deformation transmitted across large parts of the magma chamber prior to its final crystallization. The grain-scale mechanisms of biotite fabric acquisition in the schlieren presumably involved rotation of biotite crystals during flow, with the biotite alignment reflecting the flow geometry and kinematics, replaced after flow cessation by melt-aided grain-boundary sliding of those biotite crystals still enclosed in melt pockets within otherwise static, highly crystallized magma mush. The latter process was sufficient to reorient biotite grains but not to cause destruction of the schlieren. Using the Jizera granite as a case example, we argue that the lattice-preferred orientation of mineral grains in mafic schlieren is highly

  6. Thrusting and sedimentation along an emergent thrust front: an example from the External Sierras of the Southern Pyrenees, Spain

    SciTech Connect

    Anastasio, D.J.; De Paor, D.G.

    1985-01-01

    Depending on the relative rates of thrusting and erosion, emergent thrusts, like glaciers, may advance or retreat while continually moving forward. The relative rates of thrusting and erosion as a thrust ruptures the land surface also control the mountain front geometry. For listric thrusts, the high angle of intersection with the land surface results in primarily upward rather than horizontal movement. If thrust movement is much faster than the prevailing erosion a large emergent toe will develop as the thrust sheet advances over its synorogenic deposits. Alternatively, if the erosion rates are generally faster than thrusting, synorogenic deposits will progressively onlap onto a receding mountain front. Comparable rates of thrusting and erosion result in steady state uplift and denudation. In the External Sierras the thrust front reached the synorogenic surface during the Paleogene and resulted in the accumulation of thick synorogenic deposits. Relatively slow rates of thrusting (<1mm/a) and uplift (<0.5mm/a) of the External Sierras, coupled with moderate erosion rates resulted in a near stationary mountain front. Despite this, temporal and spatial fluctuations in the thrusting resulted in three different mountain front geometries. In places, the thrust front has been buried by molasse, elsewhere, the emergent thrust sheet has deformed its proximal molasse by bulldozing, producing deposits analogous to push moraines, and in other places the frontal thrust has overridden its molasse. Striated cobbles within the molasse immediately below the frontal thrust may have functioned like ball bearings, reducing the friction with the overriding thrust sheet.

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

    NASA Astrophysics Data System (ADS)

    Masson, Frédéric; Henrion, Eric; Ulrich, Patrice

    2016-04-01

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

  8. Geodetic networks in Al-Hoceima, Fez-Meknes and Ouarzazate regions (Morocco) to monitor local deformations

    NASA Astrophysics Data System (ADS)

    Gil, A. J.; Ruiz, A. M.; Lacy, M. C.; Galindo-Zaldívar, J.; Anahnah, F.; Ruano, P.; Álvarez-Lobato, P. Ayarza, F.; Arboleya, A. Teixel, M. L.; Azzouz, O.; Ahmamou, A. Chalouan, M.; Kchikach, A.

    2009-04-01

    In the framework of some interdisciplinary research projects, several geodetic studies have been initiated aiming to quantify ground deformation in some areas of Morocco: the Al-Hoceima region (Rif cordillera), the Fez-Meknes region and the Ouarzazate region (Atlas Mountains). The Al-Hoceima region, located in the central part of the Rif Cordilleras, has undergone an intense seismic activity, in which the most significant events occurred in 1994 and 2004 (M= 6.3). Although seismicity data support the presence of transcurrent faults, and available radar interferometry researches evidence surface deformations, geological data suggest that main seismogentic fault zone has not a surface expression. Anyway, a set of N-S oriented normal faults (Rouadi, Al-Hoceima, Trougout) determines the present-day geomorphology and seems to continue to be active in surface. In this area, a new non-permanent GPS network consisting of 6 sites has been installed and surveyed in June 2007 and September 2008. The repeated measurements of this network may allow to exactly determine the surface expression of deep tectonic deformations in this region, and to quantify the creep and the coseismic motions in the area, that will contribute to better understand the seismic hazard. The Prerif Ridges located in the Fez-Meknes region, constitute the active mountain front of the Rif cordillera that accommodates most of the recent convergence between Eurasia and African plates. South of the ridges, the Saïss foreland basin overlies the foreland rocks corresponding to the Middle Atlas. There are evidences of Quaternary uplift of the Prerif Ridges and deformation of recent sediments as consequence of the southwards propagation of reverse faults along the mountain front. In addition, the foreland basin undergoes a roughly N-S extensional regime. The region undergoes a moderate seismic activity, with catastrophic events like that occurred in 1755 which damaged Fez and Meknes. On September 2007, a non

  9. Paleocene deep basin coals related to a transpressional zone of the Laramide deformation front

    SciTech Connect

    Cavaroc, V.V.; Flores, R.M.

    1994-12-31

    Mining in the Hanna Coal Field of south-central Wyoming has concentrated in the relatively small (about 450 sq mi) Hanna Basin. The basin, which appears to have developed in response to transpressional stresses associated with Laramide tectonic development, accumulated at least two miles of fluvial dominated, coal-bearing continental detritus during the Paleocene Epoch. The stratigraphic sequence of the basin consists of two major, overall fining-upward detrital cycles which constitute the Ferris and overlying Hanna Formations. A major change in detrital source direction indicates these cycles are of tectonic origin. The base of both cycles is characterized by the prevalence of pebbly to conglomeratic sandstone; these become generally less abundant and finer grained upward. Conglomeratic sequences occur near faulted basin margins. Most coal, including at least fifty seams that are greater than five feet in thickness, are concentrated in the upper portion of the Ferris and lower to middle portion of the Hanna interval. Analyses of thirty coal samples indicate a Btu range of 10,630 to 11,670, an ash range of 3.9 to 34.7%, and sulfur content ranging from 0.3 to 6.2%. Palynologic analyses of organic-rich shales provide correlation across the field area.

  10. Deformation Front Development at the Northeast Margin of the Tainan Basin, Tainan-Kaohsiung Area, Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, Shiuh-Tsann; Yang, Kenn-Ming; Hung, Jih-Hao; Wu, Jong-Chang; Ting, Hsin-Hsiu; Mei, Wen-Wei; Hsu, Shiang-Horng; Lee, Min

    2004-03-01

    The geological setting south of the Tsengwen River and the Tsochen Fault is the transitional zone between the Tainan foreland basin and Manila accretionary wedge in Southwestern Taiwan. This transitional zone is characterized by the triangle zone geological model associated with back thrusts that is quite unique compared to the other parts of the Western foreland that are dominated by thrust imbrications. The Hsinhua structure, the Tainan anticline, and the offshore H2 anticline are the first group of major culminations in the westernmost part of the Fold-and-Thrust belt that formed during the Penglay Orogeny. Structures in the the Tainan and Kaohsiung areas provide important features of the initial mountain building stage in Western Taiwan. A deeply buried basal detachment with ramp-flat geometry existed in the constructed geological sections. A typical triangle is found by back thrusting, such as where the Hsinhua Fault cuts upsection of the Upper Pliocene and Pleistocene from a lower detachment along the lower Gutingkeng Formation. The Tainan structure is a southward extension of the Hinhua Fault and has an asymmetric geometry of gentle western and steep eastern limbs. Our studies suggest that the Tainan anticline is similar to the structure formed by the Hsinhua Fault. Both are characterized by back thrusts and rooted into a detachment about 5 km deep. The triangle zone structure stops at H2 anticline offshore Tainan and beyond the west of it, All the structures are replaced by rift tectonic settings developed in the passive continental margin. On the basal detachment, a major ramp interpreted as a tectonic discontinuity was found in this study. Above the northeastern end of the major ramp of basal detachment, the Lungchuan Fault is associated with a triangle system development, while at the southwestern end a thrust wedge is present. It could be deduced that a thrust wedge intrudes northwestward. The area below the major ramp, or equivalent to the trailing edge of the basal detachment, mud diapers often occur in relation to the thickest deposits of the Gutingkeng Formation and caused by the mechanism of detachment folding

  11. Development of a curvature wave-front sensor for the GUIELOA adaptive optics system

    NASA Astrophysics Data System (ADS)

    Chapa, Oscar; Cuevas, Salvador; Sánchez, Beatriz; Cantó, Jordi; Mendoza, Héctor

    2006-02-01

    GUIELOA is a Curvature type Adaptive Optics system for the 2.1 m San Pedro Martir Telescope. It performs a bimorph 19 actuators deformable mirror and a 19 lens-let array for the wave-front sensor (WFS). GUIELOA corrects effectively the first 8 Zernike polynomials of the aberrated wave-front produced by the atmospheric turbulence. For the closed loop control it performs two SPARC FORCE 5 SBC computers working in concert. The lens-let array + optical fibers send the light from defocused pupil images to 19 avalanche photo-diodes. In this work it is shown how the lens-let array was manufactured at IAUNAM with CIDESI and Centro de Investigaciones en Optica (CIO).

  12. A geometric deformable model for echocardiographic image segmentation

    NASA Technical Reports Server (NTRS)

    Hang, X.; Greenberg, N. L.; Thomas, J. D.

    2002-01-01

    Gradient vector flow (GVF), an elegant external force for parametric deformable models, can capture object boundaries from both sides. A new geometric deformable model is proposed that combines GVF and the geodesic active contour model. The level set method is used as the numerical method of this model. The model is applied for echocardiographic image segmentation.

  13. Plate Margin Deformation and Active Tectonics Along the Northern Edge of the Yakutat Terrane in the Saint Elias Orogen, Alaska and Yukon, Canada

    NASA Technical Reports Server (NTRS)

    Bruhn, Ronald L.; Sauber, Jeanne; Cotton, Michele M.; Pavlis, Terry L.; Burgess, Evan; Ruppert, Natalia; Forster, Richard R.

    2012-01-01

    The northwest directed motion of the Pacific plate is accompanied by migration and collision of the Yakutat terrane into the cusp of southern Alaska. The nature and magnitude of accretion and translation on upper crustal faults and folds is poorly constrained, however, due to pervasive glaciation. In this study we used high-resolution topography, geodetic imaging, seismic, and geologic data to advance understanding of the transition from strike-slip motion on the Fairweather fault to plate margin deformation on the Bagley fault, which cuts through the upper plate of the collisional suture above the subduction megathrust. The Fairweather fault terminates by oblique-extensional splay faulting within a structural syntaxis, allowing rapid tectonic upwelling of rocks driven by thrust faulting and crustal contraction. Plate motion is partly transferred from the Fairweather to the Bagley fault, which extends 125 km farther west as a dextral shear zone that is partly reactivated by reverse faulting. The Bagley fault dips steeply through the upper plate to intersect the subduction megathrust at depth, forming a narrow fault-bounded crustal sliver in the obliquely convergent plate margin. Since . 20 Ma the Bagley fault has accommodated more than 50 km of dextral shearing and several kilometers of reverse motion along its southern flank during terrane accretion. The fault is considered capable of generating earthquakes because it is linked to faults that generated large historic earthquakes, suitably oriented for reactivation in the contemporary stress field, and locally marked by seismicity. The fault may generate earthquakes of Mw <= 7.5.

  14. Control of Precambrian basement deformation zones on emplacement of the Laramide Boulder batholith and Butte mining district, Montana, United States

    USGS Publications Warehouse

    Berger, Byron R.; Hildenbrand, Thomas G.; O'Neill, J. Michael

    2011-01-01

    What are the roles of deep Precambrian basement deformation zones in the localization of subsequent shallow-crustal deformation zones and magmas? The Paleoproterozoic Great Falls tectonic zone and its included Boulder batholith (Montana, United States) provide an opportunity to examine the importance of inherited deformation fabrics in batholith emplacement and the localization of magmatic-hydrothermal mineral deposits. Northeast-trending deformation fabrics predominate in the Great Falls tectonic zone, which formed during the suturing of Paleoproterozoic and Archean cratonic masses approximately 1,800 mega-annum (Ma). Subsequent Mesoproterozoic to Neoproterozoic deformation fabrics trend northwest. Following Paleozoic through Early Cretaceous sedimentation, a Late Cretaceous fold-and-thrust belt with associated strike-slip faulting developed across the region, wherein some Proterozoic faults localized thrust faulting, while others were reactivated as strike-slip faults. The 81- to 76-Ma Boulder batholith was emplaced along the reactivated central Paleoproterozoic suture in the Great Falls tectonic zone. Early-stage Boulder batholith plutons were emplaced concurrent with east-directed thrust faulting and localized primarily by northwest-trending strike-slip and related faults. The late-stage Butte Quartz Monzonite pluton was localized in a northeast-trending pull-apart structure that formed behind the active thrust front and is axially symmetric across the underlying northeast-striking Paleoproterozoic fault zone, interpreted as a crustal suture. The modeling of potential-field geophysical data indicates that pull-apart?stage magmas fed into the structure through two funnel-shaped zones beneath the batholith. Renewed magmatic activity in the southern feeder from 66 to 64 Ma led to the formation of two small porphyry-style copper-molybdenum deposits and ensuing world-class polymetallic copper- and silver-bearing veins in the Butte mining district. Vein orientations

  15. Dislocation Mechanics of High-Rate Deformations

    NASA Astrophysics Data System (ADS)

    Armstrong, Ronald W.; Li, Qizhen

    2015-10-01

    Four topics associated with constitutive equation descriptions of rate-dependent metal plastic deformation behavior are reviewed in honor of previous research accomplished on the same issues by Professor Marc Meyers along with colleagues and students, as follow: (1) increasing strength levels attributed to thermally activated dislocation migration at higher loading rates; (2) inhomogeneous adiabatic shear banding; (3) controlling mechanisms of deformation in shock as compared with shock-less isentropic compression experiments and (4) Hall-Petch-based grain size-dependent strain rate sensitivities exhibited by nanopolycrystalline materials. Experimental results are reviewed on the topics for a wide range of metals.

  16. Strain localization during deformation of Westerly granite

    NASA Technical Reports Server (NTRS)

    Brodsky, N. S.; Spetzler, H. A.

    1984-01-01

    A specimen of Westerly granite was cyclically loaded to near failure at 50 MPa confining pressure. Holographic interferometry provided detailed measurements of localized surface deformations during loading and unloading. The data are consistent with deformation occurring primarily elastically at low differential stress; in conjunction with one incipient fault zone between approximately 350 and 520 MPa differential stress; and in conjunction with a second incipient fault zone above 580 MPa and/or during creep. During unloading only one fault zone, that which is active at the intermediate stress levels during loading, is seen to recede.

  17. [Babies with cranial deformity].

    PubMed

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

    2009-01-01

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

  18. Probing deformed quantum commutators

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  19. Deformed wing virus.

    PubMed

    de Miranda, Joachim R; Genersch, Elke

    2010-01-01

    Deformed wing virus (DWV; Iflaviridae) is one of many viruses infecting honeybees and one of the most heavily investigated due to its close association with honeybee colony collapse induced by Varroadestructor. In the absence of V.destructor DWV infection does not result in visible symptoms or any apparent negative impact on host fitness. However, for reasons that are still not fully understood, the transmission of DWV by V.destructor to the developing pupae causes clinical symptoms, including pupal death and adult bees emerging with deformed wings, a bloated, shortened abdomen and discolouration. These bees are not viable and die soon after emergence. In this review we will summarize the historical and recent data on DWV and its relatives, covering the genetics, pathobiology, and transmission of this important viral honeybee pathogen, and discuss these within the wider