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Sample records for active deformation front

  1. Space active optics: performance of a deformable mirror for in-situ wave-front correction in space telescopes

    NASA Astrophysics Data System (ADS)

    Laslandes, Marie; Hourtoule, Claire; Hugot, Emmanuel; Ferrari, Marc; Lopez, Céline; Devilliers, Christophe; Liotard, Arnaud; Chazallet, Frederic

    2012-09-01

    MADRAS (Mirror Active, Deformable and Regulated for Applications in Space) project aims at demonstrating the interest of Active Optics for space applications. We present the prototype of a 24 actuators, 100 mm diameter deformable mirror to be included in a space telescope's pupil relay to compensate for large lightweight primary mirror deformation. The mirror design has been optimized with Finite Element Analysis and its experimental performance characterized in representative conditions. The developed deformable mirror provides an efficient wave-front correction with a limited number of actuators and a design fitting space requirements.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. First paleoseismological assessment of active deformation along the eastern front of the southern Alps (NE Italy, Friuli). Insights on the 1511 earthquake causative fault.

    NASA Astrophysics Data System (ADS)

    Falcucci, Emanuela; Eliana Poli, Maria; Galadini, Fabrizio; Paiero, Giovanni; Scardia, Giancarlo; Zanferrari, Adriano

    2014-05-01

    The study area belongs to the Julian Prealps that represent the easternmost portion of the Plio-Quaternary front of the eastern Southalpine Chain (ESC), a south-verging polyphase fold and thrust belt, in evolution from the Middle Miocene to the Present. Here, the WSW-ENE trending, SW- verging thrusts of the ESC join the NW-SE trending, right-lateral strike slip Idrija fault system, which develops along the Italian-Slovenian boundary. The area is characterized by medium/high seismicity testified by both large historical and instrumental earthquakes. The DBMI11 (Locati et al., 2011) records the 1348 Carinzia earthquake (Mw= 7.02), the 1511 Idrija earthquake (Mw=6.98), and the 1976 Friuli earthquakes on May (Mw=6.46) and September (Mw=5.98) We studied a segment of the Susans-Tricesimo thrust system, namely the Colle Villano (CV) thrust, identified by means of geological and geophysical investigations (Galadini et al., 2005). New geological and geomorphological analyses allowed identifying the surficial geomorphic evidence of recent blind thrusting along the structure, represented by gentle scarps and surface warping. In order to characterise the Late Pleistocene-Holocene activity of this blind thrust, paleoseismological investigations were performed along one of CV thrust-related fault scarps. We dug three trenches ~1 km to the north of the Magredis village. The analysis of the trench walls allowed identifying deformation events induced by the fault activity. Two subsequent episodes of deformation are distinguished by localised warping (few metres in wave length) of the sedimentary sequences exposed by the excavations and secondary extrados faulting. One event occurred between 544-646 AD (radiocarbon cal. age, 2σ) and 526-624 AD the other - probably the last one - occurred close to 1485-1604 AD. The last displacement event is consistent with the aforementioned 1511 earthquake both in terms of chronology of the deformation and location of the causative fault. This

  7. 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.

  8. 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.

  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. 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.

  11. 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.

  12. 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

  13. Range-front deformation on the northern limb of the Manastash Anticline, Yakima Fold Belt, Washington

    NASA Astrophysics Data System (ADS)

    Ladinsky, T. C.; Kelsey, H. M.; Sherrod, B. L.; Pratt, T. L.

    2010-12-01

    The Manastash Ridge range front on the south edge of the Kittitas Valley near Ellensburg Washington is a prominent north-facing range front within the Yakima fold belt that hosts a suite of landforms that may reflect active faulting. Quaternary mapping on LiDAR imagery of the northern limb provides evidence for episodic uplift and/or base level lowering that may be associated with crustal shortening of the Manastash anticline. The geomorphic evolution of the Manastash front is preserved through terrace sequences and uplifted alluvial fan deposits. Abandoned terraces record prior positions of the Yakima River. Field verification of the LiDAR mapping corroborated a series of fan deposits that record periods of sedimentation from short, steep drainages issuing north off the Manastash range front. Subsequently, the fans were modified through erosion by the Yakima River. Therefore, terrace sequences locally are proximal to the mouths of the short, steep drainages. Field exposures indicate that the lower terraces are composed of alluvial fill, while higher terraces are incised into bedrock with a surficial cover. The sequence of Quaternary alluvial deposits and terraces suggest a minimum of three base level-lowering events adjacent to the Manastash front. From the lack of well developed loess cover on lowest terrace, we infer that the most recent base level lowering event was latest Pleistocene or Holocene. Abandoned terraces and fan deposits are consistent with the interpretation that the Manastash Ridge is translating upward relative to the Kittitas Valley. Each base level lowering event may be a manifestation of co-seismic slip on a blind fault underlying the range front. If such a blind fault is responsible for base level lowering, the sense of slip is unclear from abandoned terraces alone. However, bedrock exposures along Shushuskin Canyon, a valley that drains north out of the range front, exhibit a tight syncline within the northern limb of the anticline. This

  14. 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

  15. 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.

  16. 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

  17. Analysis of Faulting and Sediment Velocity Characteristics Outboard of the Cascadia Deformation Front from Multi-Channel Seismic Data.

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Faulting of the sediment section on the downgoing Juan de Fuca Plate (JdF) outboard of the Cascadia deformation front is explored using multi-channel seismic (MCS) data collected in 2012 during the JdF Ridge to Trench Survey (MGL1211). MCS data were collected along two full plate transects ("Oregon" (ORT) and "Washington" (WAT)) and one trench parallel line. Sediment velocity analysis is conducted via semblance spectrums on common mid-point super gathers spaced at a 625 m interval. Higher sediment velocities are found in the north, which may reflect the regional differences in sediment composition evident in existing drill holes located along our transects (DSDP site 174 - ORT and ODP site 1027 - WAT) that indicate higher smectite content along the ORT (bulk composition +44%). Accordingly, observations of fault frequency, dip, and throw along both transects show significant differences in faulting characteristics across the JdF plate. Faulting extends ~175 km (8.2 - 1.9 Ma plate age) from the deformation front along the WAT, and reaches a maximum fault density of ~0.48 fault/km in the region between 25 - 113 km (7.5 - 4 Ma plate age). Evidence of faulting extends ~300 km (8.9 - 2.6 Ma plate age) from the deformation front along the ORT and reaches a similar high fault density of ~0.48 fault/km in the region between 113 - 138 km (7.07 - 5.96 Ma plate age). Analysis of fault offset indicates growth faults along both transects. Along the ORT, maximum fault throws remain ~uniform at 10 - 15 m for crustal ages of 7.07 - 5.96 Ma and beginning ~75 km from the deformation front increase landward to maximum throws of 30 m, consistent with increasing fault strain due to flexural bending of the downgoing plate. In contrast, along the WAT, there is no evidence of increasing fault throw toward the deformation front. High fault dips (45 - 70°) are found in the region of highest fault density on both transects. Lower dips (35 - 60°) are measured in the region of increasing

  18. 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.

  19. 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

    2016-04-01

    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.

  20. Robust Wave-front Correction in a Small Scale Adaptive Optics System Using a Membrane Deformable Mirror

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Park, S.; Baik, S.; Jung, J.; Lee, S.; Yoo, J.

    A small scale laboratory adaptive optics system using a Shack-Hartmann wave-front sensor (WFS) and a membrane deformable mirror (DM) has been built for robust image acquisition. In this study, an adaptive limited control technique is adopted to maintain the long-term correction stability of an adaptive optics system. To prevent the waste of dynamic correction range for correcting small residual wave-front distortions which are inefficient to correct, the built system tries to limit wave-front correction when a similar small difference wave-front pattern is repeatedly generated. Also, the effect of mechanical distortion in an adaptive optics system is studied and a pre-recognition method for the distortion is devised to prevent low-performance system operation. A confirmation process for a balanced work assignment among deformable mirror (DM) actuators is adopted for the pre-recognition. The corrected experimental results obtained by using a built small scale adaptive optics system are described in this paper.

  1. Seismic Analysis across the Deformation Front: implications for channel migration in the upper reach of the Penghu Submarine Canyon, Offshore Southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Han, Wei-Chung; Liu, Char-Shine; Chi, Wu-Cheng; Wang, Yun-shuen

    2014-05-01

    This study analyzes both 2D and 3D seismic images in the upper reach of the Penghu Submarine Canyon to investigate sedimentary and structural processes in this tectonically active zone. The study area lies across the deformation front which separates the rifted South China Sea (SCS) continental slope to the west from the submarine Taiwan accretionary wedge to the east. Using 3D seismic images, several structural and sedimentary features have been identified: in the rifted SCS slope domain, besides the paleo-slope surface, buried submarine channels and mass transport deposits (MTDs), a reverse reactivated normal fault system is recognized, while in the accretionary wedge domain, the fold and thrust structures are dominate. The reverse fault system we interpreted in the rifted SCS slope domain was a normal fault in the past, and then reactivated to become a reverse fault through the arc-continent collision processes. Since the deformation front is defined as the location of the most frontal contractional structures along a convergent plate boundary, no contractional structures should appear west of it. We thus suggest to move the location of the previously mapped deformation front further west to where the reactivated fault lies. High resolution 2D seismic and bathymetry data reveal that the directions of the paleo-submarine channels ran in an across-slope direction, while the present submarine channels head down slope in the study area. The channel migration model we proposed suggests that this might be the result of the fault reactivation. The interactions of down-slope processes and active structural controls affect the channel paths in our study area.

  2. 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.

  3. 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).

  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. 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.

  6. Generalized internal model robust control for active front steering intervention

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Zhao, Youqun; Ji, Xuewu; Liu, Yahui; Zhang, Lipeng

    2015-03-01

    Because of the tire nonlinearity and vehicle's parameters' uncertainties, robust control methods based on the worst cases, such as H ∞, µ synthesis, have been widely used in active front steering control, however, in order to guarantee the stability of active front steering system (AFS) controller, the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control. In this paper, a generalized internal model robust control (GIMC) that can overcome the contradiction between performance and stability is used in the AFS control. In GIMC, the Youla parameterization is used in an improved way. And GIMC controller includes two sections: a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters' uncertainties and some external disturbances. Simulations of double lane change (DLC) maneuver and that of braking on split- µ road are conducted to compare the performance and stability of the GIMC control, the nominal performance PID controller and the H ∞ controller. Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle's parameters variations, H ∞ controller is conservative so that the performance is a little low, and only the GIMC controller overcomes the contradiction between performance and robustness, which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller. Therefore, the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system, that is, can solve the instability of PID or LQP control methods and the low performance of the standard H ∞ controller.

  7. Versatile Membrane Deformation Potential of Activated Pacsin

    PubMed Central

    Byrnes, Laura J.; Sondermann, Holger

    2012-01-01

    Endocytosis is a fundamental process in signaling and membrane trafficking. The formation of vesicles at the plasma membrane is mediated by the G protein dynamin that catalyzes the final fission step, the actin cytoskeleton, and proteins that sense or induce membrane curvature. One such protein, the F-BAR domain-containing protein pacsin, contributes to this process and has been shown to induce a spectrum of membrane morphologies, including tubules and tube constrictions in vitro. Full-length pacsin isoform 1 (pacsin-1) has reduced activity compared to its isolated F-BAR domain, implicating an inhibitory role for its C-terminal Src homology 3 (SH3) domain. Here we show that the autoinhibitory, intramolecular interactions in pacsin-1 can be released upon binding to the entire proline-rich domain (PRD) of dynamin-1, resulting in potent membrane deformation activity that is distinct from the isolated F-BAR domain. Most strikingly, we observe the generation of small, homogenous vesicles with the activated protein complex under certain experimental conditions. In addition, liposomes prepared with different methods yield distinct membrane deformation morphologies of BAR domain proteins and apparent activation barriers to pacsin-1's activity. Theoretical free energy calculations suggest bimodality of the protein-membrane system as a possible source for the different outcomes, which could account for the coexistence of energetically equivalent membrane structures induced by BAR domain-containing proteins in vitro. Taken together, our results suggest a versatile role for pacsin-1 in sculpting cellular membranes that is likely dependent both on protein structure and membrane properties. PMID:23236520

  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. Geological and geophysical evidences of late Quaternary activity of the range-front fault along the mid-segment of the Longmen Shan thrust belt

    NASA Astrophysics Data System (ADS)

    Ren, J.; Xu, X.; Sun, X.; Tan, X.; Li, K.; Kang, W.; Liu, B.

    2011-12-01

    The Longmen Shan fault zone consists of three main Longmen Shan faults and the blind fault in the Chengdu Basin. Along the range front of the middle segment of the Longmen Shan, there is the lithological border in published geological maps. The existence and the latest active time of the range-front fault along the mid-segment of the Longmen Shan thrust belts are controversial for a long period. Petroleum seismic reflection and high-resolution shallow seismic reflection profile discovered the existence of the range-front fault and the fault offset the Quaternary strata. Based on detailed field observation, we found that there is an obvious linear feature along the mid-segment of the Longmen Shan front and the range-front fault displaced the late Quaternary fluvial terrace. Trench log indicates that a surface-rupture event occurred before ~1500a along the range-front fault. Differential GPS surveying and dating of fluvial terrace show that the range-front fault during late Quaternary underwent a vertical slip rate of bigger than 0.36mm/a, approximately equivalent to that along the main faults of the longmen Shan thrust belts, which demonstrates that the range-front fault also took an important role in accommodating the deformation of the Longmen Shan thrust zone. This study not only provides the fundamental data for seismic hazard assessment of the Chengdu Plain, but is helpful for the overall understanding of uplift mechanism of east Tibet.

  10. 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., Jr.; 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

  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. 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

  13. The role of the Montello hill in the seismicity and active deformation of Southern Alps

    NASA Astrophysics Data System (ADS)

    Pondrelli, S.; Serpelloni, E.; Danesi, S.; Lovati, S.; Massa, M.; Mastrolembo Ventura, B.; Danecek, P.; Cavaliere, A.; Salimbeni, S.

    2013-12-01

    The most remarkable geomorphological feature of the eastern Southern Alps (northern Italy) is the Montello anticline, a ~15km long SSW-NNE elongated hill, sited ~40km north of Venice, and offset of ~15 km to the south from the main pede-Alpine thrust front. It has been generated by the uplift and the deformation produced by a S-verging blind thrust, constrained by morphotectonic analyses of uplifted river terraces and sub-surface data. Despite it is presently considered as one of the main S-verging seismogenic segments of the tectonically active Southern Alps thrust front, its real seismogenic potential is still matter of debate. Although the area has been hit in 1695 by a Mw 6.5 earthquake, the Montello is currently characterized by slower seismicity activity than its confining segments and geodetic deformation rates are at the mm/yr level. In order to study the present day crustal deformation at the fault-scale and to improve the detection of background seismicity associated to the 'seismically silent' Montello thrust and to understand its interseismic behavior, we have installed a temporary multi-parametric geophysical network, which integrates space geodetic (GPS) and seismological observations during the 2010-2011 time-interval, running semi-continuous GPS experiments from 2009 to 2013. We recorded 142 local events (compared to the 43 events located by the Italian Seismic Network), located with good reliability (rms < 0.5) with Ml between 1.5 and 3.5. The available continuous and semi-continuous GPS data show that ~2 mm/yr of N-S convergence are accommodated across this sector of the Southern Alps, but the deformation signal appears more complex than what expected by a single thrust fault. GPS, although preliminary and not sampling optimally possible lateral variations of the strain-rate field, show a remarkable change of the kinematics across the external Montello thrust front. The GPS and seismological data collected during the experiment suggest that 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. 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.

  17. 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.

  18. 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

  19. Learners' Evaluations of Teacher-Fronted and Student-Centred Classroom Activities.

    ERIC Educational Resources Information Center

    Garrett, Peter; Shortall, Terry

    2002-01-01

    Investigates language learners beliefs about their experiences with different types of classroom activities, specifically teacher-fronted activities and student-centered pairwork activities. Discusses the usefulness of studying learners' beliefs about their learning experiences, their perceptions of affective and learning outcomes from these…

  20. 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

  1. 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.

  2. 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).

  3. 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

  4. 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

  5. Space active optics: in situ compensation of lightweight primary mirrors' deformations

    NASA Astrophysics Data System (ADS)

    Laslandes, M.; Ferrari, M.; Hugot, E.; Lemaitre, G.

    2010-12-01

    The need for both high quality images and light structures is a constant concern in the conception of space telescopes. The goal here is to determine how an active optics system could be embarked on a satellite in order to correct the wave front deformations of the optical train. The optical aberrations appearing in a space environment are due to mirrors' deformations, with three main origins: the thermal variations, the weightlessness conditions and the use of large weightlighted primary mirrors. We are developing a model of deformable mirror as minimalist as possible, especially in term of number of actuators, which is able to correct the first Zernike polynomials in a specified range of amplitude and precision. Flight constraints as weight, volume and power consumption are considered. Firstly, such a system is designed according to the equations from the elasticity theory: we determine the geometrical and mechanical characteristics of the mirror, the location of the forces to be applied and the way to apply them. Then the concept is validated with a Finite Element Analysis, allowing to optimize the system by taking into account parameters absent from the theory. At the end, the mirror will be realized and characterized in a representative optical configuration.

  6. Coseismic deformation during the 1989 Loma Prieta earthquake and range-front thrusting along the southwestern margin of the Santa Clara Valley, California

    USGS Publications Warehouse

    Langenheim, V.E.; Schmidt, K.M.; Jachens, R.C.

    1997-01-01

    Damage patterns caused by the 1989 Loma Prieta earthquake along the southwestern margin of the Santa Clara Valley, California, form three zones that coincide with mapped and inferred traces of range-front thrust faults northeast of the San Andreas fault. Damage in these zones was largely contractional, consistent with past displacement associated with these faults. The damage zones coincide with gravity and aeromagnetic anomalies; modeling of the anomalies defines a southwest-dipping thrust fault that places the Franciscan Complex over Cenozoic sedimentary rocks to minimum depths of 2 km. Diffuse Loma Prieta earthquake aftershocks encompass the downward projection of this modeled thrust to depths of 9 km. Our results indicate that in this region the potential for concentrated damage arising from either primary deformation along the thrust faults themselves or by sympathetic motion triggered by earthquakes on the San Andreas fault may be higher than previously recognized.

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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. PMID:25920787

  12. Active deformation and seismicity in the Southern Alps (Italy): The Montello hill as a case study

    NASA Astrophysics Data System (ADS)

    Danesi, Stefania; Pondrelli, Silvia; Salimbeni, Simone; Cavaliere, Adriano; Serpelloni, Enrico; Danecek, Peter; Lovati, Sara; Massa, Marco

    2015-06-01

    The Montello anticline is a morphotectonic feature of the east pede-mountain of the South Alpine Chain in northern Italy, which lies ca. 40 km northwest of Venice, Italy. The purpose of this study is to characterize the present-day crustal deformation and seismotectonics of the Montello area through multi-parametric geophysical observations. We used new data obtained from the installation of a temporary network of 12 seismic stations and 6 GPS sites. The GPS observations indicate that there is ~ 1 mm/yr shortening across the Montello thrust. Sites located north of the Montello thrust front deviate from the ~ NNW-ward Adria-Eurasia convergence direction, as they are constrained by a relative rotation pole in northwestern Italy that has a NNE-ward motion trend. Over 18 months, seismographic recordings allowed us to locate 142 local seismic events with Ml 0.5-3.5 with good reliability (rms < 0.5). After cross-correlation analysis, we classified 42 of these events into six clusters, with cross-correlation thresholds > 0.80. The source focal solutions indicate that: (i) there is thrusting seismic activity on the basal, sub-horizontal, portion of the Montello structure; and (ii) strike-slip source kinematics prevail on the western edge of the Montello hill. Our observations on the source mechanisms and the measured crustal deformation confirm that the Montello thrust is tectonically active.

  13. Active Printed Materials for Complex Self-Evolving Deformations

    PubMed Central

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

    2014-01-01

    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. PMID:25522053

  14. 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

    2014-01-01

    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. PMID:25522053

  15. Discontinuous fluidization transition in dense suspensions of actively deforming particles

    NASA Astrophysics Data System (ADS)

    Tjhung, Elsen; Berthier, Ludovic

    Collective dynamics of self-propelled particles at high density have been shown to display a glass-like transition with a critical slowing down of 2 to 4 orders of magnitude. In this talk, we propose a new mechanism of injecting energy or activity via volume fluctuations. We show that the behaviour of actively deforming particles is strikingly different from that of self-propelled particles. In particular, we find a discontinuous non-equilibrium phase transition from a flowing state to an arrested state. Our minimal model might also explain the collective dynamics in epithelial tissues. In particular, without needing self-propulsion or cell-cell adhesion, volume fluctuations of individual cells alone might be sufficient to give rise to an active fluidization and collective dynamics in densely packed tissues.

  16. Cenozoic to active deformation in Western Yunnan (Myanmar China border)

    NASA Astrophysics Data System (ADS)

    Socquet, A.; Pubellier, M.

    2003-04-01

    The northward movement of India induces a right-lateral shear band from the Sunda trench to the easternmost Himalaya, where wrenching between India and Sunda plates, interfere with a clockwise flow of material around the Eastern Himalayan Syntaxis. We describe brittle and ductile deformation styles in Western Yunnan and Northern Myanmar, using field data and Landsat 7 imagery for Cenozoic structures as well as GPS and seismicity for active structures to unravel the Neogene to Present evolution. Western Yunnan is crossed by three continental-size ductile shear zones characterized by high mountain belts mainly composed of high-grade metamorphics and mylonitic rocks, and affected by active faulting. The easternmost metamorphic range, the Gaoligong Shan composed of verticalized foliated granites and mylonites is flattened westward and joins the Mogok metamorphic belt in Myanmar. East of the Gaoligong Shan, lie the Chong Shan and the Ailao / Diangcan Shan metamorphic ranges, which presents a vertical shistosity and a left-lateral motion. These three shear zones are separated by sedimentary fold-and-thrust-belts in the East, and , West of the Gaoligong, by Quaternary basins and volcanics. Preliminary results indicate that the Shan Scarp constituted the major strike-slip boundary between Indochina and India during Eocene to Miocene time, and accommodated deformation in right-lateral wrench. At the same time, the Ailao / Diangcan Shan and the Chong Shan zones were sheared left-laterally allowing the displacement toward the SE of Indochina block relative to south China. In the Miocene, ductile deformation migrated north along the Shan Scarp to the Mogok / Ruili metamorphic belt and the Gaoligong belt, dragging the Chong Shan right-laterally and superimposing a late right-lateral ductile deformation on its metamorphic rocks. The present-day relative motion between India and Sundaland, inferred from GPS processing, reaches 35 mm / yr in the Myanmar area. It is classically

  17. Using Digital Topography to Differentiate Erosionally Exhumed and Tectonically Active Mountains Fronts

    NASA Astrophysics Data System (ADS)

    Frankel, K. L.; Pazzaglia, F. J.

    2003-12-01

    Mountain ranges in the southern Rocky Mountains have departed on unique landscape evolutionary pathways in the late Cenozoic that are directly dependent upon the degree of post-orogenic tectonic activity they have experienced. The topography of Sierra Nacimiento, a Laramide uplift in west-central New Mexico lacking an active range-front fault, is shaped primarily by erosional exhumation that is continuous, but not steady, being driven by distal base level fall from Rio Grande incision and resultant south to north knickpoint migration. In contrast, the topography of the Taos Range, a rift flank uplift in north-central New Mexico is shaped by contrasting active stream incision and aggradation astride an active range front normal fault. The distinction between exhumation-dominated and tectonically-dominated mountain fronts is best quantified by analyses of a new metric we call the drainage basin volume to drainage basin area ratio (V-A ratio) as well as the gradients of first-order streams. Drainage basin volume and area are calculated by constructing topographic envelope maps from 10 m resolution digital elevation models (DEM). The envelope maps are pinned by the watershed divide and cover the maximum elevations in each drainage basin. Subtracting the original DEM from the maximum elevation envelope map produces a topographic residual map from which area and volume data can be obtained. The erosionally exhumed Sierra Nacimiento has a mean V-A ratio of 88 m while the tectonically active Taos Range has a mean V-A ratio of 140 m. Similarly, there are systematic differences in the gradients of first order streams measured both in the range block and approximately 5 km of adjacent piedmont. Streams were defined and subsequently Strahler ordered by a flow accumulation threshold of 250 water-equivalent grid cell units. First order stream channel long profiles were extracted from the DEM at 30 meter increments and gradients were calculated by a FORTRAN program. Gradients of

  18. Active deformation along the Andaman-Nicobar subduction zone from seismic reflection studies

    NASA Astrophysics Data System (ADS)

    Moeremans, R. E.; Singh, S. C.

    2013-12-01

    The Andaman-Sumatra subduction zone is one of the most seismically active regions on Earth and is a prime example of oblique subduction. It is the result of the oblique convergence between the downgoing Indo-Australian and the overriding Eurasian plates, leading to slip partitioning into a trench-normal thrust component along the plate interface and a trench-subparallel strike-slip component along a sliver fault. The direction of convergence is 90° with respect to the trench near Java, reduces to 45° off of northern Sumatra, and becomes almost parallel to the trench along the Andaman-Nicobar portion of the subduction. Rates of subduction vary from 63 mm/yr off of Java, 50 mm/yr near Nias Island, 45 mm/yr northwest of Sumatra, and 39 mm/yr near the Andaman Islands. After the great December 2004 earthquake, the Sumatran section of the subduction zone was heavily investigated using marine geophysical studies, but the deformation processes in the Andaman-Nicobar region remain poorly understood due to the lack of data. Here, we present seismic reflection profiles from the Andaman-Nicobar region that cover the deformation front, the forearc high, and the forearc basin. We find that the presence of thick (> 3 s TWT) sediments lead to slip taking place predominantly along landward vergent frontal faults. The frontal fault vergence changes to seaward due to the thinning (< 2 s TWT) of the sediments in the region where the Ninetyeast ridge subducts. The presence of a thick (> 3 s TWT) 20 km-long unit of undeformed sediments, possibly resulting from the landward vergence of the frontal thrusts, suggests that ~40 km of the Ninetyeast ridge has subducted beneath the Andaman forearc. The forearc is widest between the Andaman and Nicobar Islands, likely due to the subduction of thick sediments. The forearc basin is bounded in the west by a series of backthrusts and is underlain by a continental crust, which was once a part of the Malay Peninsula. The forearc basin is crescent

  19. 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

  20. 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

  1. Active control of a large deformable mirror for future E-ELT

    NASA Astrophysics Data System (ADS)

    Gasmi, R.; Le Bihan, D.; Dournaux, J. L.; Sinquin, J. C.; Jagourel, P.

    2010-07-01

    Increasing dimensions of ground based telescopes and adaptive optics needs for these instruments require wide deformable mirrors with a high number of actuators to compensate the effects of the atmospheric turbulence on the wave fronts. The new dimensions and characteristics of these deformable mirrors lead to the apparition of structural vibrations, which may reduce the rejection band width of the adaptive optics control loop. The aim of this paper is the study of the dynamic behavior of a 1-meter prototype of E-ELT's deformable mirror in order to identify its eigenmodes and to propose some ways to control its vibrations. We first present the first eigenmodes of the structure determined by both finite element analysis and experimental modal analysis. Then we present the frequency response of the prototype to a tilt excitation to estimate the effects of its vibrations on the adaptive optics loop. Finally we suggest a method to control the dynamics of the deformable mirror.

  2. Microseismicity and active deformation of Messinia, SW Greece

    NASA Astrophysics Data System (ADS)

    Papoulia, J.; Makris, J.

    By deploying a 30 3-component digital seismic array in the Messiniakos gulf and the surrounding region, we recorded for a period of 45 days the microseismic activity. With a minimum of six records per event, we located 1121 earthquakes corresponding to an average of 20 events per day. For the hypocenter location we used a local velocity model adopted to two controlled source seismic experiments. Within the array, traveltime residuals were within ± 0.2 s and the epicentral accuracy in the order of ± 2 km, while the hypocentral one is twice this value. Correlation of the seismicity with the tectonic elements indicated that most of the NW-SE oriented faults are active with strike-slip movement along this orientation and extension perpendicular to it. The neogene basins of Messini, Meligalas and Megalopolis are seismically very active and their eastern flanks are delineated by higher seismic activity than their western ones. This indicates that the basins are asymmetric with master faults defining their eastern-northeastern flanks. This hypothesis is supported by the asymmetric structure mapped at the offshore Messiniakos basin as densely spaced high resolution reflection seismic profiles have revealed. The western margins of the basins are less deformed and the seismic activity is dispersed over several minor NW-SE faults. Since the NW-SE striking faults onshore are truncated by major NE-SW oriented ones, their overall length is shortened, reducing their seismic potential and capacity to store large stresses that could produce events above Ms6.1. Offshore western Messinia, in the Ionian Sea, the size and activity of the faults is significantly larger and prone to develop events of larger magnitudes. Subcrustal seismicity indicates a deepening of the foci to the east-northeast.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  9. Water flow based geometric active deformable model for road network

    NASA Astrophysics Data System (ADS)

    Leninisha, Shanmugam; Vani, Kaliaperumal

    2015-04-01

    A width and color based geometric active deformable model is proposed for road network extraction from remote sensing images with minimal human interception. Orientation and width of road are computed from a single manual seed point, from which the propagation starts both right and left hand directions of the starting point, which extracts the interconnected road network from the aerial or high spatial resolution satellite image automatically. Here the propagation (like water flow in canal with defined boundary) is restricted with color and width of the road. Road extraction is done for linear, curvilinear (U shape and S shape) roads first, irrespective of width and color. Then, this algorithm is improved to extract road with junctions in a shape of L, T and X along with center line. Roads with small break or disconnected roads are also extracts by a modified version of this same algorithm. This methodology is tested and evaluated with various remote sensing images. The experimental results show that the proposed method is efficient and extracting roads accurately with less computation time. However, in complex urban areas, the identification accuracy declines due to the various sizes of obstacles, over bridges, multilane etc.

  10. Molecular dynamics simulations of transducin: interdomain and front to back communication in activation and nucleotide exchange.

    PubMed

    Ceruso, Marc A; Periole, Xavier; Weinstein, Harel

    2004-04-30

    The dynamic events that underlie the nucleotide exchange process for the Galpha subunit of transducin (Galpha(t)) were studied with nanosecond time-scale molecular dynamics simulations. The modeled systems include the active and inactive forms of the wild-type Galpha(t) and three of its mutants (GDP-bound form only): F332A, A322S, and Q326A that are known to exhibit various degrees of enhancement of their basal and receptor-catalyzed rates of nucleotide exchange (150-fold, 70-fold and WT-like, respectively). The results of these computational experiments reveal a number of nucleotide-dependent structural and dynamic changes (involving the alpha(B)-alpha(C) loop, the inter-domain orientation of the helical and GTPase domains and the alpha(5) helix) that were not observed in the various crystal structures of Galpha(t). Notably, the results show the existence of a front to back communication device (involving the beta(2)-beta(3) hairpin, the alpha(1) helix and the alpha(5) helix), strategically located near all elements susceptible to be involved in receptor-mediated activation/nucleotide exchange. The wild-type simulations suggest that the dynamic interplay between the elements of this device would be critical for the activation of the Galpha(t) subunit. This inference is confirmed by the results of the computational experiments on the mutants that show that even in their GDP-bound forms, the A322S and F332A mutants acquire an "active-like" structure and dynamics phenotype. The same is not true for the Q326A mutant whose structural and dynamic properties remain similar to those of the GDP-bound WT. Taken together the results suggest a nucleotide exchange mechanism, analogous to that found in the Arf family GTPases, in which a partially activated state, achievable from a receptor-mediated action of the front to back communication device either by displacement of the C-terminal alpha(5) helix, of the N-terminal alpha(N) helix, or of the Gbetagamma subunit, could

  11. Decadal to millennial deformation in the Pamir - Tian Shan collision zone, NW China and surface expression of active tectonics

    NASA Astrophysics Data System (ADS)

    Bufe, A.; Bookhagen, B.; Burbank, D. W.; Bekaert, D. P.; Hussain, E.

    2013-12-01

    The collision between the Pamir and the Tian Shan is a type example of intracontinental collision. GPS studies show that in Northwest China, at the junction between the Tarim basin, the Pamir and the Tian Shan, 7-9 mm/y of north-south shortening are presently accommodated across the boundary between the two orogens. Here, the deformation has mostly stepped out from the high mountain front into the foreland and has formed a complex array of compressional structures. We compare rates of decadal deformation in the area with 104- to 106-year estimates and investigate the extent to which stream profiles and topography reflect the active tectonics in this setting. A dataset of decadal deformation rates around the Tarim-Tian Shan-Pamir junction in Northwest China is obtained from Interferometric Synthetic Aperture Radar (InSAR) time-series analysis. We use the StaMPS/MTI package to combine small-baseline and persistent-scatterer techniques and obtain results that show no significant residual topographic phase correlation. Our data show that deformation has stepped away from the high mountain front and is concentrated on a few structures in the foreland of the Pamir and Tian Shan. Line-of-sight deformation of up to 2-4 mm/y on the Pamir Frontal Thrust (PFT) and the Kashi detachment anticline are observed. No significant displacement of the Main Pamir Thrust can be detected. Within error, the modern deformation rates agree with previously published millennial to million-year estimates along the PFT. However, decadal deformation rates deviate from million-year shortening and rock-uplift rates of anticlines in the foreland of the Tian Shan. It remains unclear whether the discrepancy arises from a recent change to a new persistent uplift rate, or merely from short timescale fluctuation of uplift rate, for example within an earthquake cycle. In an additional step, we extract stream profiles and normalized steepness index (ksn) values for rivers with drainage areas larger than 9

  12. 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

  13. 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).

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

    USGS Publications Warehouse

    Battaglia, Maurizio; Cervelli; 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. State of Hydration of the Juan de Fuca Plate Along the Cascadia Deformation Front from Controlled-Source Wide-Angle Seismic Data

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Understanding the structure and state of hydration of the young Juan de Fuca (JdF) Plate prior to being subducted beneath Cascadia is important because water incorporated into the downgoing plate plays a critical role in many subduction zone processes. Here we present the structure of the JdF plate along a ~400-km-long wide-angle seismic profile extending from offshore Northern WA to offshore Central OR, ~10 km seaward from the Cascadia deformation front (CDF). Vp in the lower crust decreases from north to south: 7.0-7.1 km/s north of 46°N, and 6.85-6.95 km/s south of 45°30'N. Vp in the upper 2.5 km of the mantle is highest north of 46°50N (7.85-7.95 km/s) and south of the 45°N (7.85-8.1 km/s). In between these latitudes, mantle Vp is 7.75-7.85 km/s north of 45°45'N, and reaches a minimum value of 7.55 km/s at 45°15'N. MCS images across the southern part of the plate show evidence for faulting in the lower crust and upper mantle while images across the northern part of the plate do not [Han et al., this meeting]. Therefore we interpret the along-CDF variations in lower crustal and upper mantle velocity largely resulting from the increasing north-to-south effect of bending-related faulting. Taking into account plate age, inferred thermal structure, and expected mantle anisotropy, we explore end-member scenarios on the amount of fracturing and water stored in the lower crust and uppermost mantle of the JdF plate off the CDF. Assuming that Vp variations are due to fractures containing free H2O, we estimate that lower crust/upper mantle porosity increases from <0.1% north of 46°N to 0.15-0.25% to the south of this latitude, with free H2O content at these depths reaching a maximum of 0.08 wt% between 45°15'-30'N. At the other end of the spectrum, Vp variations may be explained by fractures filled-in with hydration products such as serpentine; in which case we estimate a porosity south of 46°N as large as 5-9%, with chemically-bounded H2O content reaching a

  17. 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

  18. Extremely Reduced Motion in Front of Screens: Investigating Real-World Physical Activity of Adolescents by Accelerometry and Electronic Diary

    PubMed Central

    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

  19. 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

  20. 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.

  1. Active Fibers: Matching Deformable Tract Templates to Diffusion Tensor Images

    PubMed Central

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

    2009-01-01

    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. PMID:19457360

  2. On the initial stage of plastic deformation of metal alloys

    SciTech Connect

    Zuev, L.B.; Danilov, V.I.; Zavodchikov, S.Y.

    2000-04-01

    Plastic deformation has been studied for a range of metal alloys using speckle interferometry. It has been found that, in the initial stage, the process of plastic flow occurs by the propagation of a deformation front, which divides the deforming material into two regions differing with respect to the material's state. The flow exhibits regular features that can be described in terms of a self-excited wave process manifesting itself in an active medium under external mechanical action.

  3. 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

  4. 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.

  5. Inspiratory muscle fatigue affects latissimus dorsi but not pectoralis major activity during arms only front crawl sprinting.

    PubMed

    Lomax, Mitch; Tasker, Louise; Bostanci, Ozgur

    2014-08-01

    The purpose of this study was to determine whether inspiratory muscle fatigue (IMF) affects the muscle activity of the latissimus dorsi and pectoralis major during maximal arms only front crawl swimming. Eight collegiate swimmers were recruited to perform 2 maximal 20-second arms only front crawl sprints in a swimming flume. Both sprints were performed on the same day, and IMF was induced 30 minutes after the first (control) sprint. Maximal inspiratory and expiratory mouth pressures (PImax and PEmax, respectively) were measured before and after each sprint. The median frequency (MDF) of the electromyographic signal burst was recorded from the latissimus dorsi and pectoralis major during each 20-second sprint along with stroke rate and breathing frequency. Median frequency was assessed in absolute units (Hz) and then referenced to the start of the control sprint for normalization. After IMF inducement, stroke rate increased from 56 ± 4 to 59 ± 5 cycles per minute, and latissimus dorsi MDF fell from 67 ± 11 Hz at the start of the sprint to 61 ± 9 Hz at the end. No change was observed in the MDF of the latissimus dorsi during the control sprint. Conversely, the MDF of the pectoralis major shifted to lower frequencies during both sprints but was unaffected by IMF. As the latter induced fatigue in the latissimus dorsi, which was not otherwise apparent during maximal arms only control sprinting, the presence of IMF affects the activity of the latissimus dorsi during front crawl sprinting. PMID:24402450

  6. 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.

  7. 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

  8. 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

  9. Active Deformation Along the Algerian Margin (MARADJA Cruise): Framework of the May 21, 2003, Mw-6.8 Boumerdes Earthquake

    NASA Astrophysics Data System (ADS)

    Deverchère, J.; Yelles, K.; Calais, E.

    2003-12-01

    The May 21, 2003, Mw=6.8 Boumerdes earthquake (Algeria) ruptured a ˜60 km long fault, previously unknown, located a few km off the coast of Algeria, causing major damage and casualties on land. The MARADJA cruise (Suroit R/V, Aug.-Sept. 2003), dedicated to a survey of the Algerian margin in order to determine its present-day tectonic regime and identify potentially active faults, allowed for a detailed study of the Boumerdes earthquake rupture area. From a high-resolution multibeam bathymetry and back-scattering data, 3.5 kHz profiles (Chirp), 6 and 24-channel seismic reflection lines, we produced the first detailed morpho-tectonic map of the central Algerian margin and deep basin. The margin and the proximal part of the deep basin show a series of north-verging reverse faults and folds, probably developping over south-dipping ramps. The northern front of this compressional deformation zone reaches ˜20 km into the deep basin, where it interacts with salt-related deformation of the Messinian evaporites, possibly gravity driven in part, widespread in the deep basin. In the area of the May 21, 2003, earthquake, we found active fault scarps delineating a ˜60 km long fault zone at the bottom of the continental slope and at midslope, ˜17 km offshore and roughly parallel to the coast. The fault consists of at least two major segments striking N65 and N71. It might represent the place of rupture of the Boumerdes earthquake. Its location is consistent with the aftershock distribution and with preliminary dislocation models based on GPS data and uplfit observations onland. The MARADJA Scientific Party: Bouillin J-P., Bracene R., Gaullier V., Kherroubi A., Mercier de Lepinay B., Le Roy P., Pauc H., Savoye B.

  10. Evolution of Deformation Studies on Active Hawaiian Volcanoes

    NASA Astrophysics Data System (ADS)

    Decker, R.; Okamura, A.

    2004-12-01

    Summarizing 1600 years of observations and interpretations into a brief presentation forces some difficult choices on highlighting the following techniques that are presented chronologically: Visual Observations, 400 AD to present: Missionary William Ellis' Hawaiian Guides told him that Kilauea "had been burning from time immemorial, or, to use their own words, `mai ka po mai', from chaos till now...that in earlier ages it used to boil up, overflow its banks, and inundate the adjacent country...and on occasions they supposed Pele went by a road under ground from her house in the crater to the shore". Observations of the nearly-continuous lava lake in Kilauea Caldera from 1823 until 1924 established that its surface level fluctuated from about 700 to 1100 m above sea level in 10 up-and-down episodes. Tilt Measurements, 1914 to present: Horizontal-seismometer drift and water-tube tiltmeters show that the range of long-term, ground-surface tilt radial to Halemaumau Crater exceeds 500 microradians. Triangulation and Leveling, 1920: R. M. Wilson measured deformation changes related to major Kilauea summit subsidence in 1924. The caldera area around Halemaumau subsided concentrically as much as 4 m relative to the Volcano House benchmark, and triangulation points moved toward Halemaumau by as much as 1.6 m in the caldera area. K. Mogi in 1958 modeled Kilauea leveling data and inferred 3-4 km-deep magma reservoirs. Gravity Measurements, 1959 to present: Changes were first measured during Kilauea summit subsidence related to the lower-east-rift Kapoho eruption. Surveys made before and after the 1975 M7.2 Kalapana Earthquake show that gravity changes are not a simple proxy for elevation changes. Electronic Distance Measurements (EDM), 1964 to present: D. A. Swanson, W. A. Duffield, and R. S. Fiske use EDM for trilateration proving movement of the south flank of Kilauea toward the sea. EDM show displacements as large as 8.7 m of Kilauea's south flank toward the sea related

  11. Deformation Microstructure of a Reduced-Activation Ferritic/Martensitic Steel Irradiated in HFIR

    SciTech Connect

    Hashimoto, N.; Klueh, R.L.; Ando, M.; Tanigawa, H.; Sawai, T.; Shiba, K.

    2003-09-15

    In order to determine the contributions of different microstructural features to strength and to deformation mode, microstructure of deformed flat tensile specimens of irradiated reduced activation F82H (IEA heat) base metal (BM) and its tungsten inert-gas (TIG) weldments (weld metal and weld joint) were investigated by transmission electron microscopy (TEM), following fracture surface examination by scanning electron microscopy (SEM). After irradiation, the fracture surfaces of F82H BM and TIG weldment showed a martensitic mixed quasi-cleavage and ductile-dimple fracture. The microstructure of the deformed region of irradiated F82H BM contained dislocation channels. This suggests that dislocation channeling could be the dominant deformation mechanism in this steel, resulting in the loss of strain-hardening capacity. While, the necked region of the irradiated F82H TIG, where showed less hardening than F82H BM, showed deformation bands only. From these results, it is suggested that the pre-irradiation microstructure, especially the dislocation density, could affect the post-irradiation deformation mode.

  12. 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.

  13. Active optics experiments. II - Measurement of mirror deformation by holographic method

    NASA Astrophysics Data System (ADS)

    Itoh, Noboru; Mikami, Izumi; Miyawaki, Keizou; Sasaki, Aki; Tabata, Masao

    An active optics experiment was performed to study the feasibility of using an active correction system for the Japanese National Large Telescope (Wilson, 1986). A thin mirror was deformed with an active support mechanism and the mirror surface was measured by a holographic method. The experiment is performed for several cases of excess force distributions assigned at the supporting points. The results show good agreement with predictions from FEM analysis.

  14. Asymmetric counterpropagating fronts without flow.

    PubMed

    Andrade-Silva, I; Clerc, M G; Odent, V

    2015-06-01

    Out-of-equilibrium systems exhibit domain walls between different states. These walls, depending on the type of connected states, can display rich spatiotemporal dynamics. In this Rapid Communication, we investigate the asymmetrical counterpropagation of fronts in an in-plane-switching cell filled with a nematic liquid crystal. Experimentally, we characterize the different front shapes and propagation speeds. These fronts present dissimilar elastic deformations that are responsible for their asymmetric speeds. Theoretically, using a phenomenological model, we describe the observed dynamics with fair agreement. PMID:26172647

  15. Modern Tectonic Deformation in the Active Basin-And Province Northwest of Beijing, China

    NASA Astrophysics Data System (ADS)

    Mi, S.; Wen, X.

    2012-12-01

    Our study region is the northwest of Beijing, northern north China. The most typical extensional active tectonic area of the China continent, called the active basin-and-range province northwest of Beijing, exist there. This active tectonic province is made up of several NE-trending Quaternary graben basins and horst ranges between basins. An about 1500-year-long written historical record has suggested that there have been no major earthquakes with magnitude 7 or greater occurred in most of the study region since AD 512. So, the characteristic of modern tectonic deformation of the study region and its implication for the future seismic potential of major earthquakes are important scientific issues. In this study, based on data of regional GPS station velocities and active tectonics, combining relocated earthquake distribution, we make a preliminary analysis on the characteristic of the modern tectonic deformation of the study region. We design three zones across deferent segments of the active basin-and-range province to analyze both the present tectonic deformation from the GPS velocity profiles and the major fault's downward-extents from the relocated hypocenters. Our analyses reveal that: (1) Significant NNW-ward and SSE-ward horizontal extension exists on different segments of the active basin-and-range province northwest of Beijing at rates of 2 to 3mm /yr, accompanied with right-lateral shear deformation at 1 to 2mm/yr. (2) On the present tectonic deformation, the southeastern margin of the Datong-Yangyuan basin, the biggest graben basin of the active tectonic province, shows as a turning belt of the extensional rates, suggesting that relatively high tensile strain accumulation could exist there. (3)On the northeastern segment of the studied active basin-and-range province, both the Zhangjiakou-Yanhui graben basin and the Beijing graben basin have also been being in significant extensional and shear deformation. (4) The relocated hypocenter distribution have

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Coherence between geodetic and seismic deformation in a context of slow tectonic activity (SW Alps, France)

    NASA Astrophysics Data System (ADS)

    Walpersdorf, A.; Sue, C.; Baize, S.; Cotte, N.; Bascou, P.; Beauval, C.; Collard, P.; Daniel, G.; Dyer, H.; Grasso, J.-R.; Hautecoeur, O.; Helmstetter, A.; Hok, S.; Langlais, M.; Menard, G.; Mousavi, Z.; Ponton, F.; Rizza, M.; Rolland, L.; Souami, D.; Thirard, L.; Vaudey, P.; Voisin, C.; Martinod, J.

    2015-04-01

    A dense, local network of 30 geodetic markers covering a 50 × 60 km2 area in the southwestern European Alps (Briançon region) has been temporarily surveyed in 1996, 2006 and 2011 by GPS. The aim is to measure the current deformation in this seismically active area. The study zone is characterized by a majority of extensional and dextral focal mechanisms, along north-south to N160 oriented faults. The combined analysis of the three measurement campaigns over 15 years and up to 16 years of permanent GPS data from the French RENAG network now enables to assess horizontal velocities below 1 mm/year within the local network. The long observation interval and the redundancy of the dense campaign network measurement help to constrain a significant local deformation pattern in the Briançon region, yielding an average E-W extension of 16 ± 11 nanostrain/year. We compare the geodetic deformation field to the seismic deformation rate cumulated over 37 years, and obtain good coherencies both in amplitude and direction. Moreover, the horizontal deformation localized in the Briançon region represents a major part of the Adriatic-European relative plate motion. However, the average uplift of the network in an extensional setting needs the presence of buoyancy forces in addition to plate tectonics.

  18. Crustal Deformation around Zhangjiakou-Bohai Seismically Active Belt

    NASA Astrophysics Data System (ADS)

    Jin, H.; Fu, G.; Kato, T.

    2011-12-01

    Zhangjiakou-Bohai belt is a seismically active belt located in Northern China around Beijing, the capital of China. Near such a belt many great earthquakes occurred in the past centuries (e.g. the 1976 Tanshan Ms7.8 earthquake, the 1998 Zhangbei Ms6.2 earthquake, etc). Chinese Government established dense permanent and regional Global Positioning System (GPS) stations in and near the area. We collected and analyzed all the GPS observation data between 1999 and 2009 around Zhangjiakou-Bohai seismic belt, and obtained velocities at 143 stations. At the same time we investigated Zhangjiakou-Bohai belt slip rate for three profiles from northwest to southeast, and constructed a regional strain field on the Zhangjiakou-Bohai seismic belt region by least-square collocation. Based on the study we found that: 1) Nowadays the Zhangjiakou-Bohai seismic belt is creeping with left-lateral slip rate of 2.0mm~2.4mm/a, with coupling depth of 35~50km; 2) In total, the slip and coupling depth of the northwestern seismic belt is less than the one of southeast side; 3) The maximum shear strain is about 3×10-8 at Beijing-Tianjin-Tangshan area.

  19. 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.

  20. 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

  1. Chemopreventive activity of sesquiterpene lactones (SLs) from yacon against TPA-induced Raji cells deformation.

    PubMed

    Siriwan, D; Miyawaki, C; Miyamoto, T; Naruse, T; Okazaki, K; Tamura, H

    2011-05-15

    Yacon is a medicinal plant used as a traditional medicine by the natives in South America. In Japan, it becomes popular as a health food. Sesquiterpene Lactones (SLs) from yacon leaves were investigated and the active SLs such as enhydrin, uvedalin and sonchifolin, bearing alpha-methylene-gamma-lactone and epoxides as the active functional groups, were identified by 1H-6000 MHz-NMR. Chemopreventive and cytotoxic activities were determined using different primary screening methods. In this study, all tested SLs strongly inhibited TPA-induced deformed of Raji cells. The IC50 values of yacon SLs from anti-deforming assay were 0.04-0.4 microM. Interestingly, yacon SLs showed more potential of chemo preventive activity than both curcumin and parthenolide. However, the cytotoxicity on Raji cells was observed at high concentration of yacon SLs. The degree of anti-deformation was ranked in order: enhydrin >uvedalin >sonchifolin >parthenolide >curcumin. As according to structure-activity relationship, the high activities of enhydrin, uvedalin and sonchifolin may be due to the 2-methyl-2-butenoate and its epoxide moiety. PMID:22097098

  2. An adaptive integrated algorithm for active front steering and direct yaw moment control based on direct Lyapunov method

    NASA Astrophysics Data System (ADS)

    Ding, Nenggen; Taheri, Saied

    2010-10-01

    In this article, an adaptive integrated control algorithm based on active front steering and direct yaw moment control using direct Lyapunov method is proposed. Variation of cornering stiffness is considered through adaptation laws in the algorithm to ensure robustness of the integrated controller. A simple two degrees of freedom (DOF) vehicle model is used to develop the control algorithm. To evaluate the control algorithm developed here, a nonlinear eight-DOF vehicle model along with a combined-slip tyre model and a single-point preview driver model are used. Control commands are executed through correction steering angle on front wheels and braking torque applied on one of the four wheels. Simulation of a double lane change manoeuvre using Matlab®/Simulink is used for evaluation of the control algorithm. Simulation results show that the integrated control algorithm can significantly enhance vehicle stability during emergency evasive manoeuvres on various road conditions ranging from dry asphalt to very slippery packed snow road surfaces.

  3. Nocturnal activity in the cathemeral red-fronted lemur (Eulemur fulvus rufus), with observations during a lunar eclipse.

    PubMed

    Donati, G; Lunardini, A; Kappeler, P M; Borgognini Tarli, S M

    2001-02-01

    Several ecological and physiological factors have been suggested to structure circadian activity in cathemeral primates, i.e., those that are regularly active both day and night, but their relative importance remains controversial. We studied the nocturnal activity of a group of cathemeral redfronted lemurs (Eulemur fulvus rufus) in Kirindy Forest in Western Madagascar to examine its relationship with one environmental factor, ambient light levels, in detail. To this end, nightly travel distances and moon luminosity were determined between March and June 1996. During this transitional period between the wet and dry seasons these red-fronted lemurs were regularly active at night, and traveled significantly larger distances during full-moon nights compared to new-moon nights. The importance of ambient luminosity for nocturnal activity was highlighted by observations during a total lunar eclipse (i.e., during a full-moon night), which caused abrupt cessation of the animal's activity. Our results support the hypothesis that nocturnal activity of these cathemeral lemurs is regulated also by changes in ambient light levels. PMID:11170168

  4. Modern Tectonic Deformation in the Active Basin-and-Range Province Northwest of Beijing, China

    NASA Astrophysics Data System (ADS)

    Mi, Suting; Wen, Xueze

    2013-04-01

    Our study region is the northwest of Beijing, northern north China. The most typical extensional active tectonic area of the China continent, called the active basin-and-range province northwest of Beijing, exist there. This active tectonic province is made up of several NE-trending Quaternary graben basins and horst ranges between basins. An about 1500-year-long written historical record has suggested that there have been no major earthquakes with magnitude 7 or greater occurred in most of the study region since AD 512. So, the characteristic of modern tectonic deformation of the study region and its implication for the future seismic potential of major earthquakes are important scientific issues. In this study, based on data of regional GPS station velocities and active tectonics, combining relocated earthquake distribution, we make a preliminary analysis on the characteristic of the modern tectonic deformation of the study region. We design three zones across deferent segments of the active basin-and-range province to analyze both the present tectonic deformation from the GPS velocity profiles and the major fault's downward-extents from the relocated hypocenters. Our analyses reveal that: (1) Significant NNW-ward and SSE-ward horizontal extension exists on different segments of the active basin-and-range province northwest of Beijing at rates of 2 to 3mm /yr, accompanied with right-lateral shear deformation at 1 to 2mm/yr. (2) On the western and middle segments of the active basin and range province, most of the total horizontal extension and shear deformation happen in the width from the Huangqihai basin to the Datong-Yanggao basin , suggesting that some major faults in this width could have had relatively-high strain build-up. (3) It is possible that one or more basement detachment belts exist under the active basins, and it or they possibly dip(s) southeastern-ward. (4) The modern tectonic extensional rate is up to 2 to 3mm /yr in the study region. However

  5. Characterization of micro-scale creep deformation of an electro-active paper actuator

    NASA Astrophysics Data System (ADS)

    Lee, Sangwoo; Kim, Joo-Hyung; Kang, Kwangseon; Kim, Jaehwan; Kim, Heung Soo; Yang, Chulho

    2009-09-01

    The creep deformation process of an electro-active paper (EAPap) actuator was investigated by adapting stepwise dead-weight loading. To understand the deformation mechanism of the EAPap film, including morphological and structural changes, various loading conditions below yield strength were applied to cellophane EAPap. From the structural observation, micro-dimples and micro-cracks were detected at applied load lower than 10% of yield strength, while they were not found in higher load conditions. It is hypothesized that only short and random fibers in the amorphous region may respond to the applied stress at the low loading condition, not the fibers in the crystalline area. As a result, deformation energy at the localized spot accumulated and created micro-defects at the surface. Meanwhile, fibers in the crystalline region may sustain most of the loads as creep load increases to a high level. Molecular chains in the fiber may rotate and elongate with high load. Elongated fibers were observed only at a high level of load. From the structural change as a function of applied load, a peak shift of crystal orientation was observed only in high load conditions by wide angle x-ray measurement. This may confirm that creep deformation could give rise to structure changes in EAPap.

  6. Root Hair Deformation Activity of Nodulation Factors and Their Fate on Vicia sativa.

    PubMed Central

    Heidstra, R.; Geurts, R.; Franssen, H.; Spaink, H. P.; Van Kammen, A.; Bisseling, T.

    1994-01-01

    We used a semiquantitative root hair deformation assay for Vicia sativa (vetch) to study the activity of Rhizobium leguminosarum bv viciae nodulation (Nod) factors. Five to 10 min of Nod factor-root interaction appears to be sufficient to induce root hair deformation. The first deformation is visible within 1 h, and after 3 h about 80% of the root hairs in a small susceptible zone of the root are deformed. This zone encompasses root hairs that have almost reached their maximal size. The Nod factor accumulates preferentially to epidermal cells of the young part of the root, but is not restricted to the susceptible zone. In the interaction with roots, the glucosamine backbone of Nod factors is shortened, presumably by chitinases. NodRlv-IV(C18:4,Ac) is more stable than NodRlv-V(C18:4,Ac). No correlation was found between Nod factor degradation and susceptibility. Degradation occurs both in the susceptible zone and in the mature zone. Moreover, degradation is not affected by NH4NO3 and is similar in vetch and in the nonhost alfalfa (Medicago sativa). PMID:12232242

  7. Correction of an active space telescope mirror using a gradient approach and an additional deformable mirror

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    High development cost is a challenge for space telescopes and imaging satellites. One of the primary reasons for this high cost is the development of the primary mirror, which must meet diffraction limit surface figure requirements. Recent efforts to develop lower cost, lightweight, replicable primary mirrors include development of silicon carbide actuated hybrid mirrors and carbon fiber mirrors. The silicon carbide actuated hybrid mirrors at the Naval Postgraduate School do not meet the surface quality required for an optical telescope due to high spatial frequency residual surface errors. A technique under investigation at the Naval Postgraduate School is to correct the residual surface figure error using a deformable mirror in the optical path. We present a closed loop feedback gradient controller to actively control a SMT active segment and an additional deformable mirror to reduce residual wavefront error. The simulations and experimental results show that the gradient controller reduces the residual wavefront error more than an integral controller.

  8. 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.

  9. 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

  10. Crustal-scale active deformation along the Ecuadorian Andes using Persistent Scatterers SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Champenois, J.; Baize, S.; Audin, L.; Pinel, V.; Alvarado, A.; Jomard, H.; Yepes, H. A.

    2013-12-01

    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. For the last ten years, numerous multidisciplinary studies focused on major seismicity related to the subduction, whereas few investigations concentrated on M>7 crustal seismicity in the upper plate (like 1797 Riobamba earthquake, ML 8.3, 12.000 deaths). The active faults producing these earthquakes are poorly known in term of slip rate and for some cases are even not identified yet. Additionnally, Ecuador is one of the most active volcanic areas of the northern Andean volcanic zone. Three among the nine active volcanoes are actually erupting (Reventador, Tungurahua, and Sangay). For the last 5 years, geodetic networks have been deployed in Ecuador to enhance crustal deformation monitoring, but these point-wise techniques cannot provide spatially dense maps of ground deformation and are quite expensive methods. To address this issue, we applied the Persistent Scatterers SAR Interferometry technique (StaMPS/MTI freeware developed by A. Hooper) to ENVISAT SAR data between 2003 and 2009. Using these cost-effective techniques, we are able to investigate both tectonic and volcanic surface deformations with an unprecedented spatial density of measurements. This study presents new PS-InSAR results along the Ecuadorian Andes, close to the area of Riobamba. We generated average velocity maps and consistent time-series of displacements measured along the radar line of sight. These results evidence large scale deformation localized on the Pallatanga fault system (locked fault) compatible with a model of locked strike slip fault. Moreover, these results show an important growth of the Tungurahua volcanic complex (maximum rate about 9 mm/yr) with a rapid uplift prior and post 2006 explosive eruption. We investigate the time-series of displacement for 22 images. Our results permitted to propose two crustal source

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Mirror actively deformed and regulated for applications in space: design and performance

    NASA Astrophysics Data System (ADS)

    Laslandes, Marie; Hugot, Emmanuel; Ferrari, Marc; Hourtoule, Claire; Singer, Christian; Devilliers, Christophe; Lopez, Céline; Chazallet, Frédéric

    2013-09-01

    The need for both high quality images and lightweight structures is one of the main drivers in space telescope design. An efficient wavefront control system will become mandatory in future large observatories, retaining performance while relaxing specifications in the global system's stability. We present the mirror actively deformed and regulated for applications in space project, which aims to demonstrate the applicability of active optics for future space instrumentation. It has led to the development of a 24-actuator, 90-mm-diameter active mirror, able to compensate for large lightweight primary mirror deformations in the telescope's exit pupil. The correcting system has been designed for expected wavefront errors from 3-m-class lightweight primary mirrors, while also taking into account constraints for space use. Finite element analysis allowed an optimization of the system in order to achieve a precision of correction better than 10 nm rms. A dedicated testbed has been designed to fully characterize the integrated system performance in representative operating conditions. It is composed of: a telescope simulator, an active correction loop, a point spread function imager, and a Fizeau interferometer. All conducted tests demonstrated the correcting mirror performance and has improved this technology maturity to a TRL4.

  18. Active deformation in the frontal part of the Northern Apennines: insights from the lower Metauro River basin area (northern Marche, Italy) and adjacent Adriatic off-shore

    NASA Astrophysics Data System (ADS)

    Di Bucci, D.; Mazzoli, S.; Nesci, O.; Savelli, D.; Tramontana, M.; De Donatis, M.; Borraccini, F.

    2003-09-01

    scattered, and depths are generally comprised within the first 20 km of the crust, clustering between 0 and 15 km. Most of the events have magnitude <3.0, while only a few of them (12) have magnitude between 3.0 and 4.2. Focal mechanisms were obtained for eight events. The results are complex, showing fault plane solutions of "normal fault", "thrust fault" and "unknown" types, according to commonly used stress categories. The low level of seismicity and the inhomogeneity of fault plane solutions confirm that, in the study area, this kind of data cannot provide clear constraints with respect to the problem of the occurrence or lack of activity along the thrust front. Finally, the Quaternary marine succession was studied in the northern Adriatic off-shore. Lower Pleistocene deposits appear to be slightly involved in the deformation associated with the frontal thrust of the Apennine chain. In contrast, the upper part of the Quaternary succession is clearly undeformed, showing planar and horizontal reflectors, which seal the most external thrusts of the belt. These data suggest that thrusting at the front of the Northern Apennines ended in Early Pleistocene times. Our integrated results indicate that, since Middle Pleistocene times, the external front of the northern Marche Apennines has been inactive. A generalised uplift has taken place, with subordinate tectonic activity being characterised by ENE-WSW extension and NNW-SSE compression. These main features of the stress field, although with spatial permutations of the principal stress axes, also characterise most of the external Northern Apennines during the whole Middle Pleistocene-Holocene time span.

  19. 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. PMID:24782676

  20. 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

  1. 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.

  2. Low resistivity and permeability in actively deforming shear zones on the San Andreas Fault at SAFOD

    NASA Astrophysics Data System (ADS)

    Morrow, C.; Lockner, D. A.; Hickman, S.

    2015-12-01

    The San Andreas Fault Observatory at Depth (SAFOD) scientific drill hole near Parkfield, California, crosses the San Andreas Fault at a depth of 2.7 km. Downhole measurements and analysis of core retrieved from Phase 3 drilling reveal two narrow, actively deforming zones of smectite-clay gouge within a roughly 200 m wide fault damage zone of sandstones, siltstones, and mudstones. Here we report electrical resistivity and permeability measurements on core samples from all of these structural units at effective confining pressures up to 120 MPa. Electrical resistivity (~10 Ω-m) and permeability (10-21 to 10-22 m2) in the actively deforming zones were 1 to 2 orders of magnitude lower than the surrounding damage zone material, consistent with broader-scale observations from the downhole resistivity and seismic velocity logs. The higher porosity of the clay gouge, 2 to 8 times greater than that in the damage zone rocks, along with surface conduction were the principal factors contributing to the observed low resistivities. The high percentage of fine-grained clay in the deforming zones also greatly reduced permeability to values low enough to create a barrier to fluid flow across the fault. Together, resistivity and permeability data can be used to assess the hydrogeologic characteristics of the fault, key to understanding fault structure and strength. The low resistivities and strength measurements of the SAFOD core are consistent with observations of low resistivity clays that are often found in the principal slip zones of other active faults making resistivity logs a valuable tool for identifying these zones.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Research on the Calculated Methods of Active Control Value for Antenna Panel Deformations under Gravity

    NASA Astrophysics Data System (ADS)

    Fu, L.; Zhong, W. Y.; Qiao, H. H.; Liu, G. X.; Qian, H. L.

    2015-07-01

    The methods of ideal reflector surface, two-parameter, five-parameter, and six-parameter best-fit paraboloid are presented in this paper. Based on these methods, the adjustment values of gravity deformations are calculated for the main reflector of large-scale Cassegrain antenna. Accordingly, the positions of subreflector are corrected, and the effects of offset-focus on electric performance are also analyzed. Taking Shanghai 65 m antenna as a research object, the adjustment values of actuator and hexapod, the accuracy of the main reflector surface, and the pointing error after offsetting the focus are contrasted. As a result, the method of six-parameter best-fit paraboloid is ideal to calculate active control value for antenna panels after the effects of feed defocus have been adjusted and modified. The results offer data for the active control of antenna.

  8. 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.

  9. 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

  10. 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.

  11. Seismic Reflection Images of Deep Lithospheric Faults and Thin Crust at the Actively Deforming Indo-Australian Plate Boundary in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Singh, S. C.; Carton, H.; Chauhan, A.; Dyment, J.; Cannat, M.; Hananto, N.; Hartoyo, D.; Tapponnier, P.; Davaille, A.

    2007-12-01

    Recently, we acquired deep seismic reflection data using a state-of-the-art technology of Schlumberger having a powerful source (10,000 cubic inch) and a 12 km long streamer along a 250 km long trench parallel line offshore Sumatra in the Indian Ocean deformation zone that provides seismic reflection image down to 40 km depth over the old oceanic lithosphere formed at Wharton spreading centre about 55-57 Ma ago. We observe deep penetrating faults that go down to 37 km depth (~24 km in the oceanic mantle), providing the first direct evidence for full lithospheric-scale deformation in an intra-plate oceanic domain. These faults dip NE and have dips between 25 and 40 degrees. The majority of faults are present in the mantle and are spaced at about 5 km, and do not seem cut through the Moho. We have also imaged active strike-slip fault zones that seem to be associated with the re-activation of ancient fracture zones, which is consistent with previous seismological and seafloor observations. The geometries of the deep penetrating faults neither seem to correspond to faulting associated with the plate bending at the subduction front nor with the re-activation of fracture zone that initiated about 7.5 Ma ago, and therefore, we suggest that these deep mantle faults were formed due to compressive stress at the beginning of the hard collision between India and Eurasia, soon after the cessation of seafloor spreading in the Wharton basin. We also find that the crust generated at the fast Wharton spreading centre 55-57 Ma ago is only 3.5-4.5 km thick, the thinnest crust ever observed in a fast spreading environment. We suggest that this extremely thin crust is due to 40-50°C lower than normal mantle temperature in this part of the Indian Ocean during its formation.

  12. 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…

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. Active deformation in the inner western Alps inferred from comparison between 1972-classical and 1996-GPS geodetic surveys

    NASA Astrophysics Data System (ADS)

    Sue, Christian; Martinod, Joseph; Tricart, Pierre; Thouvenot, François; Gamond, Jean-François; Fréchet, Julien; Marinier, Delphine; Glot, Jean-Paul; Grasso, Jean-Robert

    2000-04-01

    Eighteen geodetic points surveyed in 1972 by the French National Geographic Institute (IGN) were remeasured by GPS in 1996 in the Briançonnais and Piémont Zones, east of the Pelvoux massif (French Western Alps). A displacement vector set was determined for the two surveys' common points. Calculations of the strain-rate tensors associated with 15 triangular cells of the network have been performed. Only four of them show a strain rate significant at a 95% level of confidence. These data suggest an E-W extension of about 2-4 mm/yr between the western and eastern part of the network (Pelvoux external crystalline massif and Queyras blueschists, respectively) associated with N-S shortening. This active deformation agrees with neotectonic and seismotectonic data. The measured tectonic motion seems to be distributed throughout the central part of the Briançonnais zone, where the seismic activity is concentrated. The local seismicity has been precisely surveyed since 1989. It is moderate ( Ml<4.7) and no larger earthquake occured in the 1972-1989 period. The seismic deformation of the 1972-1996 period, extrapolated from the 1989-1996 local seismicity, accounts for less than 10% of the geodetic deformation. Thus, aseismic processes accommodated more than 90% of the observed deformation during this period. This could correspond to accumulation of elastic strain on locked faults, creep on faults or plastic deformation in a large crustal volume.

  19. 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.

  20. Characterization of actin filament deformation in response to actively driven microspheres propagated through entangled actin networks

    NASA Astrophysics Data System (ADS)

    Falzone, Tobias; Blair, Savanna; Robertson-Anderson, Rae

    2014-03-01

    The semi-flexible biopolymer actin is a ubiquitous component of nearly all biological organisms, playing an important role in many biological processes such as cell structure and motility, cancer invasion and metastasis, muscle contraction, and cell signaling. Concentrated actin networks possess unique viscoelastic properties that have been the subject of much theoretical and experimental work. However, much is still unknown regarding the correlation of the applied stress on the network to the induced filament strain at the molecular level. Here, we use dual optical traps alongside fluorescence microscopy to carry out active microrheology measurements that link mechanical stress to structural response at the micron scale. Specifically, we actively drive microspheres through entangled actin networks while simultaneously measuring the force the surrounding filaments exert on the sphere and visualizing the deformation and subsequent relaxation of fluorescent labeled filaments within the network. These measurements, which provide much needed insight into the link between stress and strain in actin networks, are critical for clarifying our theoretical understanding of the complex viscoelastic behavior exhibited in actin networks.

  1. 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.

  2. Rates and kinematics of active shortening along the eastern Qilian Shan, China, inferred from deformed fluvial terraces

    NASA Astrophysics Data System (ADS)

    Hu, Xiaofei; Pan, Baotian; Kirby, Eric; Gao, Hongshan; Hu, Zhenbo; Cao, Bo; Geng, Haopeng; Li, Qingyang; Zhang, Guoliang

    2015-12-01

    In the eastern Qilian Shan, a flight of fluvial terraces developed along the Jinta River valley are deformed across the Nanying anticline. Four individual fluvial terraces are preserved at different elevations above the river, and higher terrace treads are draped by systematically thicker aeolian loess. Optically stimulated luminescence dating of deposits at the base of the loess provides constraints on the timing of surface abandonment; terraces were abandoned at 69 ± 4 ka B.P. (T4), 57 ± 4 ka B.P. (T3), and between 34 ± 3 ka B.P. (T2), respectively. Differential GPS measurement of the terrace profile across the anticline allows reconstruction of subsurface fault geometry; we model terrace deformation above a listric thrust fault with a tip line at 2.2 ± 0.1 km depth and whose dip shallows systematically to 23 ± 3° at depth of 5.8 ± 1.1 km. Combining terrace ages with this model of fault geometry, we estimate a shortening rate of 0.8 ± 0.2 mm/a across the Nanying fold and a shortening rate of ~0.1 mm/a across the mountain front fault since ~70 ka B.P. This rate suggests that the frontal fault system along the eastern Qilian Shan accomplishes crustal shortening at rates of approximately 0.9 ± 0.3 mm/a during late Pleistocene time.

  3. Tectonic and gravity-induced deformation along the active Talas-Fergana Fault, Tien Shan, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Tibaldi, A.; Corazzato, C.; Rust, D.; Bonali, F. L.; Pasquarè Mariotto, F. A.; Korzhenkov, A. M.; Oppizzi, P.; Bonzanigo, L.

    2015-08-01

    This paper shows, by field palaeoseismological data, the Holocene activity of the central segment of the intracontinental Talas-Fergana Fault (TFF), and the relevance of possible future seismic shaking on slope stability around a large water reservoir. The fault, striking NW-SE, is marked by a continuous series of scarps, deflected streams and water divides, and prehistoric earthquakes that offset substrate and Holocene deposits. Fault movements are characterised by right-lateral strike-slip kinematics with a subordinate component of uplift of the NE block. Structural, geological and geomorphological field data indicate that shallow and deep landslides are aligned along the TFF, and some of them are active. Where the TFF runs close to the reservoir, the fault trace is obscured by a series of landslides, affecting rock and soil materials and ranging in size from small slope instabilities to deep-seated gravity-induced slope deformations (DGSDs). The largest of these, which does not show clear evidence of present-day activity, involves a volume of about 1 km3 and is associated with smaller but active landslides in its lower part, with volumes in the order of 2.5 × 104 m3 to 1 × 106 m3. Based on the spatial and temporal relations between landslides and faults, we argue that at least some of these slope failures may have a coseismic character. Stability analyses by means of limit equilibrium methods (LEMs), and stress-strain analysis by finite difference numerical modelling (FDM), were carried out to evaluate different hazard scenarios linked to these slope instabilities. The results indicate concern for the different threats posed, ranging from the possible disruption of the M-41 highway, the main transportation route in central Asia, to the possible collapse of huge rock masses into the reservoir, possibly generating a tsunami.

  4. 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

  5. TerraSAR InSAR Investigation of Active Crustal Deformation

    NASA Astrophysics Data System (ADS)

    Lei, L.; Burgmann, R.

    2009-12-01

    We aim to utilize advanced analysis of TerraSAR-X data to investigate the dynamics and interactions of solid Earth deformation processes, such as earthquakes and fault creep, and Earth surface processes, such as land subsidence and groundwater movements, in a densely populated, urban region, the San Francisco Bay Area. Ongoing deformation imaging reveals a number of natural hazards including elastic strain accumulation about seismologic faults, active landsliding, land subsidence and rebound, and settling of unconsolidated sediments that are highly susceptible to liquefaction. Up to now, we have ordered and received 20 more TerraSAR-X Spotlight Single Look Complex (SLC) images and a few Stripmap SLC images delivered by DLR and got a few preliminary results. The TerraSAR-X images were acquired over the San Francisco Bay Area particularly around an area of active landsliding, coastal subsidence and shallow Hayward fault creep near the city of Berkeley. Berkeley is situated between latitude 37.45 and 38.00, longitude 237.30 and 238.00. The data acquisition interval is from November, 2008 to now. Four types of Spotlight images and one type of Stripmap images in time sequence were ordered and acquired: spot_012, spot_038, spot_049, spot_075 and strip_003, having different look angles and pass directions. Access to the SAR data is via ftp about 10 days after acquisition date. The data is supplied in TerraSAR-X standard SLC COSAR (COmplex SAR) format with orbital information in an Extensible Markup Language (XML) header. The file contains integer real-complex components with double sampling and calibration constants for values. I am using ROI_PAC to do the interferograms. But ROI_PAC was designed to process the raw data rather SLC images. So there are some problems in azimuth processing with TerraSAR SLC data especially the Spotlight data. We now have some preliminary results of Stripmap interferograms and Spotlight interferograms but still work on those problems and

  6. 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

  7. 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

  8. 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

  9. Front Matter.

    PubMed

    2016-01-01

    requirements for supporting holistic, person-centred, integrated care systems in the Netherlands, and beyond. STC Programme The call for papers has resulted in 70 submissions from 30 countries, which were peer-reviewed by over 160 highly appreciated experts of the EFMI biomedical informatics network. Over 400 authors and co-authors are involved in the accepted contributions that shape the programme. The conference starts with a key contribution from Bernard Benhamou entitled Internet of Things & Medicine: A European Perspective. Then, Peter Pharrow explains how 'We are entering the era of the Internet of (every)-Thing'. Christian Lovis, as the third keynote speaker, ends the conference by addressing the key to 'Moving from a care-driven system to a health-centred paradigm: active objects, data, and information'. The reviewing process has demonstrated that, up to now, the scientific work related to the IoT in healthcare has been focused on a mix of technologically-driven issues, but the potential to reform the health and social care systems is still underexploited. This can be seen as a positive sign, as the scientific world first wants to understand and prove the potential of the IoT before widely implementing it within the healthcare system. Accepted contributions reflect the scientific work on the impact of the IoT and the societal dimensions of the IoT in the sessions related to the transformation of healthcare, while the sessions on ontologies, decision support, clinical information systems, and data reuse complete the programme. To enrich the scientific sessions, the conference also offers tutorials, workshops, posters, short communications, demonstrations and a plenary panel. From Sunday 17th to Tuesday 19th April 2016, Paris will not only be the city of light, but also the centre for world-citizens involved in the changing of traditional health care. It is with respect for the history of French medicine that the LIMICS chose the "Ecole de médecine" (created in 1794

  10. Gravity and deformation changes at two persistently active volcanoes: Insights into magmatic processes

    NASA Astrophysics Data System (ADS)

    Williams-Jones, G.; Rymer, H.

    2004-05-01

    Insights on some of the mechanisms responsible for persistent volcanism can be best achieved through the synergy of temporal geophysical and geochemical data sets. Gravity changes combined with ground deformation have been shown to provide important information on magma reservoir mass changes while measurements of gas flux have been influential in determining the rate of magma emplacement. The integration of long-term micro-gravity and ground deformation data with SO2 flux and total sulphur budgets collected at Poás and Masaya volcanoes (since 1983 and 1993, respectively) now allows for the identification of significant cycles of activity. Recent eruptive activity at Poás volcano (Costa Rica) has been characterised by the disappearance and subsequent reappearance of the summit crater lake following intrusive episodes in 1980 and 1986-1989. Magma approached the surface on both occasions and was detected by the observation of concurrent increases in micro-gravity. These increases can be best modelled in terms of brittle fracturing of a shallow magma carapace allowing magma ascent through the conduit system to beneath the crater. This process allows for the vertical transfer of heat and gas and is driven by convection of buoyant, volatile-rich magma displacing colder, degassed magma. As magma pressure drops, the connection between the deeper magma reservoir and shallow conduit system is severed allowing the hydrothermal system to resume its role as a cooling mechanism. In contrast, recent activity at Masaya volcano (Nicaragua) has been characterised by repeated periods of significant passive degassing (>2000 t/d SO2) with the eruption of only negligible amounts of juvenile material. The resulting cycle gravity and gas flux variations is clearly not driven by intrusion of additional magma into the shallow system. Rather, it may be due in part to blocking and gas accumulation caused by restrictions in the shallow volcano substructure. However, as with Poás, this

  11. Earthquake relocations, crustal rheology, and active deformation in the central-eastern Alps (N Italy)

    NASA Astrophysics Data System (ADS)

    Viganò, Alfio; Scafidi, Davide; Ranalli, Giorgio; Martin, Silvana; Della Vedova, Bruno; Spallarossa, Daniele

    2015-10-01

    A revised seismic catalogue (1994-2007) for the central-eastern Alps (N Italy) is presented. 396 earthquake relocations, for local magnitudes in the 1.2-5.3 range, are performed using a 3D crustal velocity structure and probabilistic locations. The location procedure is validated by computing a set of 41 quarry shot solutions and all the results, both about shots and seismic events, are compared with those obtained using the routine location procedure. Results are shown for five contiguous seismotectonic domains, as supported by geological and geophysical evidence (e.g., fault systems, crustal tomography, focal mechanisms types). Earthquake hypocentres are mostly located in the upper crust (0-15 km of depth), in good agreement with thermo-rheological models about the brittle-ductile transitions (8-9 km of depth) and total crustal strengths (1.0-2.0 TN m- 1). Epicentres are clustered and/or aligned along present-day active geological structures. The proposed seismotectonic model shows dominant compression along the Giudicarie and Belluno-Bassano-Montello thrusts, with strain partitioning along the dominant right-lateral strike-slip faults of the Schio-Vicenza domain. The present-day deformation of the Southern Alps and the internal Alpine chain is compatible with Adria indentation and the related crustal stress distribution.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  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.

    2015-11-01

    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.

  19. 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

  20. 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.

  1. 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

  2. Perceptual transparency from image deformation

    PubMed Central

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

    2015-01-01

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

  3. Characterising Seismicity at Alutu, an Actively Deforming Volcano in the Main Ethiopian Rift

    NASA Astrophysics Data System (ADS)

    Wilks, M.; Nowacki, A.; Kendall, J. M.; Wookey, J. M.; Biggs, J.; Bastow, I. D.; Ayele, A.; Bedada, T.

    2013-12-01

    The Main Ethiopian Rift (MER) provides a unique example of the tectonic and volcanic processes occuring during the transition from continental rifting to oceanic spreading. Situated 100 km south of Addis Ababa along the eastern rift margin, Alutu is a silicic stratovolcano that geodetic measurements (InSAR and GPS) have shown is actively deforming. Though the volcano has received relatively little scientific attention it is also a site of economic significance as a geothermal power plant resides within the caldera. As part of ARGOS (Alutu Research Geophysical ObservationS), a multi-disciplinary project aiming to investigate the magmatic and hydrothermal processes occuring at Alutu, a seismic network of 12 broadband seismometers was deployed in January 2012. Other components of ARGOS include InSAR, GPS, geologic mapping and magnetotellurics. From the seismic dataset, P- and S-wave arrivals across the array were manually picked and used to locate events using a non-linear earthquake location algorithm (NonLinLoc) and a predefined 1D velocity model. Perturbations were later applied to this velocity model to investigate the sensitivity of the locations and evaluate the true uncertainties of the solutions. Over 1000 events were successfully located during 2012, where picks were possible at 4 or more stations. Seismicity clusters at both shallow depths (z<2 km) beneath the caldera and at deeper depths of 5-15 km. There is a significant increase in seismicity during the rainy months, suggesting the shallow events may be related to the hydrothermal system. We interpret the deeper events as being magmatic in origin. Events are also located along the eastern border faults that bound the outer edges of the MER and highlights that seismicity arises concurrently via tectonic processes. An adapted version of Richter's original local magnitude scale (ML) to account for attenuation within the MER (Keir et al., 2006) was then used to compute magnitudes for the best located events

  4. 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

  5. Pulse front adaptive optics in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The accurate focusing of ultrashort laser pulses is extremely important in multiphoton microscopy. Using adaptive optics to manipulate the incident ultrafast beam in either the spectral or spatial domain can introduce significant benefits when imaging. Here we introduce pulse front adaptive optics: manipulating an ultrashort pulse in both the spatial and temporal domains. A deformable mirror and a spatial light modulator are operated in concert to modify contours of constant intensity in space and time within an ultrashort pulse. Through adaptive control of the pulse front, we demonstrate an enhancement in the measured fluorescence from a two photon microscope.

  6. Pulse front control with adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  7. 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

  8. 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.

  9. Earthquake Cycle Deformation and GPS: A Quantitative Computer-Based Activity for Undergraduate Students

    NASA Astrophysics Data System (ADS)

    Marshall, S. T.

    2012-12-01

    Earthquake cycle deformation and geodetic measurements of tectonic strain are well represented in recent peer-reviewed literature; however, because of the quantitative nature of these topics, students are often given only a conceptual description of these processes and techniques at the undergraduate level. Here, I present a computer-based assignment appropriate for Sophomore-level undergraduate students in either a structural geology, tectonics, or geophysics course. The assignment introduces students to the classic analytical earthquake cycle equations for a vertical strike-slip fault. While the equations alone are relatively non-intuitive for understanding earthquake cycle deformation, modern computer applications (e.g Maple, Excel, Matlab, Mathematica, etc…) can be used to easily produce graphs of the equations that are much more meaningful for understanding tectonics. The advantage of having students create their own plots is that once the plots have been created, students can tweak model parameters (locking depth and slip rate) to see how the resultant deformation would change. Thus, the students can effectively create their own earthquake cycle deformation tool that can be tweaked to fit real or hypothetical data. The assignment ends by having students determine the interseismic slip rate and locking depth on the San Andreas fault given actual Plate Boundary Observatory Data that is provided to them. The overarching goals of the assignment are to encourage students to make their own tools and graphics for learning new concepts and to encourage the next generation of geologists to pursue quantitative tectonic studies in their academic and/or professional futures.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Feedback between erosion and active deformation: geomorphic constraints from the frontal Jura fold-and-thrust belt (eastern France)

    NASA Astrophysics Data System (ADS)

    Madritsch, Herfried; Fabbri, Olivier; Hagedorn, Eva-Marie; Preusser, Frank; Schmid, Stefan M.; Ziegler, Peter A.

    2010-10-01

    A regional tectono-geomorphic analysis indicates a Pliocene to recent rock uplift of the outermost segment of the Jura fold-and-thrust belt, which spatially coincides with the intra-continental Rhine-Bresse Transfer Zone. Elevated remnants of the partly eroded Middle Pliocene Sundgau-Forêt de Chaux Gravels identified by heavy mineral analyses allow for a paleo-topographic reconstruction that yields minimum regional Latest Pliocene to recent rock uplift rates of 0.05 ± 0.02 mm/year. This uplift also affected the Pleistocene evolution of the Ognon and Doubs drainage basins and is interpreted as being tectonically controlled. While the Ognon River was deflected from the uplifted region the Doubs deeply incised into it. Focused incision of the Doubs possibly sustained ongoing deformation along anticlines which were initiated during the Neogene evolution of the thin-skinned Jura fold-and-thrust belt. At present, this erosion-related active deformation is taking place synchronously with thick-skinned tectonics, controlling the inversion of the Rhine-Bresse Transfer Zone. This suggests local decoupling between seismogenic basement faulting and erosion-related deformation of the Mesozoic cover sequences.

  18. 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

  19. 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.

  20. 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.

  1. Study of the active deformation of Mitidja (Tell Atlas, Algeria) by GPS

    NASA Astrophysics Data System (ADS)

    Bacha, Wahab; Masson, Frederic; Yelles-Chaouche, Abdelkrim; Lammali, Kamel; Bellik, Amar; Hamai, Lamine

    2013-04-01

    A network was created in the Mitidja region around the capital Algiers (Algeria). It has been established to study the deformation of the region and the slow operation of flaws in it. The network was installed by a distribution of GPS stations according to structural domains existing in the region. Twelve bases spread across the study area, have been installed. The measurements were acquired by performing four measurement campaigns in 2006, 2007, 2009 and 2010, with sessions over a month of action. This work allowed the installation of a geodetic network of regional monitoring by methodology GPS in the zone of Mitidja (Tellian Atlas, Algeria). Four observation campaigns were carried out on this area with session's superiors in one month of measurements. The treatment was carried out with software GAMIT-GLOBK, the network is attached to several world stations IGS treated between 2000-2010, indexed in a precise frame of reference ITRF05. The results presented in this memory show a deformation in shortening ≤ 0.5 mm/an in the plain of Mitidja and the surrounding Solid masses.

  2. The three-dimensional pattern of crustal deformation associated with active normal fault systems observed using continuous GPS geodesy

    NASA Astrophysics Data System (ADS)

    Bennett, R. A.; Hreinsdottir, S.

    2009-12-01

    Geological examples of shallow dipping normal faults with large displacements are exposed at numerous locations throughout the world and it is widely recognized that extensional deformation at brittle crustal levels is most efficiently accomplished by slip across such structures. It has previously been shown that lower dip angles reduce the regional stresses required to drive large horizontal displacements. Nevertheless, the traditional theory of fault mechanics—based on Anderson’s classification of stress regimes, the Coulomb failure criterion, and Byerlee’s friction law—precludes such faults from slipping at low angle. Observational support for this traditional theory includes the absence of large unequivocally low-angle normal fault earthquakes in the global catalog; all well-determined normal fault earthquakes appear to have occurred on moderate to steeply dipping planes. However, precise measurements of 3D crustal motions based on continuous GPS in central Italy and Utah reveal deformation patterns across active normal fault systems that are inconsistent with active slip across steeply dipping planes. Instead, the combination of observed horizontal and vertical surface motions are consistent with slip across low angle surfaces independently imaged in the subsurface by seismic reflection and other geophysical data. For the Alto Tiberina fault in central Italy, active aseismic creep occurs at shallow crustal levels, most likely within the brittle-frictional regime at which Andersonian-Byerlee fault mechanics should be applicable. The actively creeping portion of the fault inferred using GPS geodesy correlates well with the observed pattern of micro-seismicity, which concentrates along the inferred subsurface fault plane. GPS measurements across the greater Wasatch fault zone in the vicinity of Salt Lake City, Utah, reveal crustal motions consistent with aseismic displacement across a shallow dipping fault or sub-horizontal shear zone at mid

  3. 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

  4. 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

  5. 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

  6. 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.

  7. Estimation of active faulting in a slow deformation area: Culoz fault as a case study (Jura-Western Alps junction).

    NASA Astrophysics Data System (ADS)

    de La Taille, Camille; Jouanne, Francois; Crouzet, Christian; Jomard, Hervé; Beck, Christian; de Rycker, Koen; van Daele, Maarten; Lebourg, Thomas

    2014-05-01

    The north-western Alps foreland is considered as still experiencing distal effects of Alpine collision, resulting in both horizontal and vertical relative displacements. Based on seismological and geodetic surveys, detailed patterns of active faulting (including subsurface décollements, blind ramps and deeper crustal thrusts have been proposed (Thouvenot et al., 1998), underlining the importance of NW-SE left-lateral strike-slip offsets as along the Vuache and Culoz faults (cf. the 1996 Epagny event: M=5.4; Thouvenot et al., 1998 and the 1822 Culoz event I=VII-VIII; Vogt, 1979). In parallel to this tectonic evolution, the last glaciation-deglaciation cycles contributed to develop large and over-deepened lacustrine basins, such as Lake Le Bourget (Perrier, 1980). The fine grain, post LGM (ie post 18 ky), sedimentary infill gives a good opportunity to evidence late quaternary tectonic deformations. This study focuses on the Culoz fault, extending from the Jura to the West, to the Chautagne swamp and through the Lake Le Bourget to the East. Historical earthquakes are known nearby this fault as ie the 1822 Culoz event. The precise location and geometry of the main fault is illustrated but its Eastern termination still needs to be determined. High resolution seismic sections and side-scan sonar images performed in the 90's (Chapron et al., 1996) showed that the Col du Chat and Culoz faults have locally deformed the quaternary sedimentary infill of the lake. These studies, mainly devoted to paleo-climate analysis were not able to determine neither the geometry of the fault, or to quantify the observed deformations. A new campaign devoted to highlight the fault geometry and associated deformation, has been performed in October 2013. Very tight profiles were performed during this high resolution seismic survey using seistec boomer and sparker sources. In several places the rupture reaches the most recent seismic reflectors underlying that these faults were active during

  8. New GPS constraints on active deformation along the Africa-Iberia plate boundary

    NASA Astrophysics Data System (ADS)

    Koulali, A.; Ouazar, D.; Tahayt, A.; King, R. W.; Vernant, P.; Reilinger, R. E.; McClusky, S.; Mourabit, T.; Davila, J. M.; Amraoui, N.

    2011-08-01

    We use velocities from 65 continuous stations and 31 survey-mode GPS sites as well as kinematic modeling to investigate present day deformation along the Africa-Iberia plate boundary zone in the western Mediterranean region. The GPS velocity field shows southwestward motion of the central part of the Rif Mountains in northern Morocco with respect to Africa varying between 3.5 and 4.0 mm/yr, consistent with prior published results. Stations in the southwestern part of the Betic Mountains of southern Spain move west-southwest with respect to Eurasia (˜ 2-3 mm/yr). The western component of Betics motion is consistent with partial transfer of Nubia-Eurasia plate motion into the southern Betics. The southward component of Betics motion with respect to Iberia is kinematically consistent with south to southwest motion of the Rif Mountains with respect to Africa. We use block modeling, constrained by mapped surface faults and seismicity to estimate the geometry and rates of strain accumulation on plate boundary structures. Our preferred plate boundary geometry includes one block between Iberia and Africa including the SW Betics, Alboran Sea, and central Rif. This geometry provides a good fit to the observed motions, suggesting a wide transpressive boundary in the westernmost Mediterranean, with deformation mainly accommodated by the Gloria-Azores fault system to the West and the Rif-Tell lineament to the East. Block boundaries encompass aspects of earlier interpretations suggesting three main deformation styles: (i) extension along the NE-SW trending Trans-Alboran shear zone, (ii) dextral strike-slip in the Betics corresponding to a well defined E-W seismic lineament, and (iii) right lateral strike-slip motion extending West to the Azores and right-lateral motion with compression extending East along the Algerian Tell. We interpret differential motion in the Rif-Alboran-Betic system to be driven both by surface processes related the Africa-Eurasia oblique convergence and

  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.

    2015-06-01

    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.

  10. 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 ...

  11. 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.

  12. Active Dehydration, Delamination and Deformation of Transitional Continental Crust in an Arc-Continent Collision, Taiwan

    NASA Astrophysics Data System (ADS)

    Byrne, T. B.; Rau, R. J.; Chen, K. H.; Huang, H. H.; Wang, Y. J.; Ouimet, W. B.

    2014-12-01

    A new study of the 3-D velocity structure of Taiwan, using a new tomographic model (Vp and Vs; Huang et al., 2014), suggests that subducted continental crust is delaminated from the subducting mantle of the Eurasia plate and progressively deformed by the subducting Philippine Sea plate. In southern Taiwan, vertical sections show an east-dipping, asymmetric lobe of low velocity that projects down dip to a band of seismicity interpreted as the Wadati-Benioff zone of the subducting Eurasian plate. Seismic tremors in the mid-crust also suggest dehydration (Chuang et al., 2014), consistent with prograde metamorphism of crustal materials. In central Taiwan, however, the seismicity of the W-B zone progressively disappears and the low velocity lobe shallows and broadens. The velocity structure of the lower and middle crust (represented by the 7.5 and 6.5 km/sec isovelocity surfaces, respectively) also appear distinctly out-of-phase, with the lower crust forming a broad, smooth synformal structure that contrasts with the higher amplitude undulations of the middle crust. These mid-crust structures appear as smaller irregular lobes separated by patches of higher velocity. In northern Taiwan, the velocity structure of the lower and middle crust again appear "in phase" and form a symmetrical crustal root centered beneath the Central Range. Seismicity patterns and 3-D analysis of the velocity structure also show the western edge of the PSP subducting beneath the eastern Central Range. We interpret these south-to-north changes to reflect the partial subduction (southern Taiwan), delamination (central Taiwan) and deformation (northern Taiwan) of continental-like crust. Support for these interpretation comes from: 1) unusually high rates of surface uplift (up to 15 mm/yr; Ching et al., 2011); 2) Vp and Vs attenuation studies that suggest anomalously high temperatures; 3) evidence for NE-SW extension; and 4) anomalous areas of low topographic relief.

  13. 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. PMID:24402364

  14. 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

  15. Madelung Deformity.

    PubMed

    Kozin, Scott H; Zlotolow, Dan A

    2015-10-01

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

  16. 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.

  17. 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.

    2016-03-01

    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.

  18. 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.

  19. Fault Activity, Seismicity and GPS Deformation of the Seismic Gap along the Red River Fault Zone (RRFZ) in Yunnan, China

    NASA Astrophysics Data System (ADS)

    Xue-Ze, Wen; Shengli, Ma; Fang, Du; Feng, Long

    2016-04-01

    Along the middle segment of the NW-trending and dextral-slip Red River fault zone (RRFZ), also the Honghe fault zone, Yunnan, China, there has been little of modern seismicity since the 1970's. Some Chinese researchers believed that this fault segment is inactive in the late Quaternary. However, more and more evidence shows that the middle segment of RRFZ is geologically-active in the late Quaternary, even is a Holocene-active one with evidence of paleo-earthquakes occurring. Our study suggests that along the fault segment there has been no any major earthquake occurring for over 500 years at least, and a large-scale seismic gap, the Honghe seismic gap, have formed there. On the modern seismicity, the middle segment of RRFZ has presented as a fault portion without or with very few small earthquakes occurring since the 1980's, but surrounded by several areas with low b-values, suggesting relatively high stress having built-up there. Also, GPS deformation analysis suggests that this fault segment has tightly locked already. Such tight locking would be associated with the fault geometry: A large-scale restraining bend of about 30°over a distance of ~100 km exists along the main fault trace along RRFZ between Yuanjiang and Yuanyang. However, how such a restraining bend makes the middle segment of RRFZ have tightly locked? How much strain has built up there? Moreover, how about the long-term seismic potential of major earthquake on the middle segment of RRFZ, and on some secondary active faults of the two sides of the segment, especially on the parallel faults Chuxiong, Qujiang and Shiping. All these are issues we want to study further. Keywords: Red River Fault Zone, Seismic Gap, Fault Activity, Seismicity, GPS Deformation

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Active deformation and shallow structure of the Wagner, Consag, and Delfín Basins, northern Gulf of California, Mexico

    NASA Astrophysics Data System (ADS)

    Persaud, Patricia; Stock, Joann M.; Steckler, Michael S.; MartíN-Barajas, Arturo; Diebold, John B.; GonzáLez-FernáNdez, Antonio; Mountain, Gregory S.

    2003-07-01

    Oblique rifting began synchronously along the length of the Gulf of California at 6 Ma, yet there is no evidence for the existence of oceanic crust or a spreading transform fault system in the northern Gulf. Instead, multichannel seismic data show a broad shallow depression, ˜70 × 200 km, marked by active distributed deformation and six ˜10-km-wide segmented basins lacking well-defined transform faults. We present detailed images of faulting and magmatism based on the high resolution and quality of these data. The northern Gulf crust contains a dense (up to 18 faults in 5 km) complex network of mainly oblique-normal faults, with small offsets, dips of 60-80° and strikes of N-N30°E. Faults with seafloor offsets of tens of meters bound the Lower and two Upper Delfín Basins. These subparallel basins developed along splays from a transtensional zone at the NW end of the Ballenas Transform Fault. Twelve volcanic knolls were identified and are associated with the strands or horsetails from this zone. A structural connection between the two Upper Delfín Basins is evident in the switching of the center of extension along axis. Sonobuoy refraction data suggest that the basement consists of mixed igneous sedimentary material, atypical of mid-ocean ridges. On the basis of the near-surface manifestations of active faulting and magmatism, seafloor spreading will likely first occur in the Lower Delfín Basin. We suggest the transition to seafloor spreading is delayed by the lack of strain-partitioned and focused deformation as a consequence of shear in a broad zone beneath a thick sediment cover.

  6. Interrogating the activities of conformational deformed enzyme by single-molecule fluorescence-magnetic tweezers microscopy.

    PubMed

    Guo, Qing; He, Yufan; Lu, H Peter

    2015-11-10

    Characterizing the impact of fluctuating enzyme conformation on enzymatic activity is critical in understanding the structure-function relationship and enzymatic reaction dynamics. Different from studying enzyme conformations under a denaturing condition, it is highly informative to manipulate the conformation of an enzyme under an enzymatic reaction condition while monitoring the real-time enzymatic activity changes simultaneously. By perturbing conformation of horseradish peroxidase (HRP) molecules using our home-developed single-molecule total internal reflection magnetic tweezers, we successfully manipulated the enzymatic conformation and probed the enzymatic activity changes of HRP in a catalyzed H2O2-amplex red reaction. We also observed a significant tolerance of the enzyme activity to the enzyme conformational perturbation. Our results provide a further understanding of the relation between enzyme behavior and enzymatic conformational fluctuation, enzyme-substrate interactions, enzyme-substrate active complex formation, and protein folding-binding interactions. PMID:26512103

  7. Interrogating the activities of conformational deformed enzyme by single-molecule fluorescence-magnetic tweezers microscopy

    PubMed Central

    Guo, Qing; He, Yufan; Lu, H. Peter

    2015-01-01

    Characterizing the impact of fluctuating enzyme conformation on enzymatic activity is critical in understanding the structure–function relationship and enzymatic reaction dynamics. Different from studying enzyme conformations under a denaturing condition, it is highly informative to manipulate the conformation of an enzyme under an enzymatic reaction condition while monitoring the real-time enzymatic activity changes simultaneously. By perturbing conformation of horseradish peroxidase (HRP) molecules using our home-developed single-molecule total internal reflection magnetic tweezers, we successfully manipulated the enzymatic conformation and probed the enzymatic activity changes of HRP in a catalyzed H2O2–amplex red reaction. We also observed a significant tolerance of the enzyme activity to the enzyme conformational perturbation. Our results provide a further understanding of the relation between enzyme behavior and enzymatic conformational fluctuation, enzyme–substrate interactions, enzyme–substrate active complex formation, and protein folding–binding interactions. PMID:26512103

  8. The Nisi Fault as a key structure for understanding the active deformation of the NW Peloponnese, Greece

    NASA Astrophysics Data System (ADS)

    Zygouri, V.; Koukouvelas, I. K.; Kokkalas, S.; Xypolias, P.; Papadopoulos, G. A.

    2015-05-01

    The previously unknown Nisi Fault in NW Peloponnese was ruptured during the 2008 Movri Mountain earthquake attaining a maximum offset of 25 cm. The fault is interpreted as a branch of a flower structure above a blind strike-slip fault. We investigate the Nisi Fault seismotectonic evolution using morphotectonic analysis in order to determine whether the landscape is affected by tectonic forcing and paleoseismology to determine earthquake recurrence interval and fault slip rates. We applied several geomorphic indices, such as the asymmetry factor (AF), the stream length-gradient index (SL), the valley floor width to valley height ratio (Vf), the mountain-front sinuosity (Smf), the drainage basin shape (Bs) and the hypsometric curve (Hc), in four large drainage basins of the study area. The results show that fault-related vertical motions and the associated tilting influenced the drainage geometry and the landscape development. Values of stream-gradient indices (SL) are relatively high close to the fault trace. Mountain-front sinuosity (Smf) mean values along the fault zones range from 1.12 to 1.23. Valley floor width to valley height ratios (Vf) mean values along the studied fault range between 0.21 and 2.50. Drainage basin shape (BS) mean values along the fault range from 1.04 to 3.72. Lateral fault growth was likely achieved by propagation primarily towards north-northwestward. The paleoseismic history of the fault, investigated by a trench and 14C dating of seven samples, indicates two morphogenic earthquakes in the last 1 kyr. Therefore, we suggest that the Nisi Fault displays a slip rate on the order of 1 mm/yr and a recurrence interval ranging between 300 and 600 years. From a seismotectonic point of view, the fault is classified as high activity rate, with abundant but discontinuous geomorphic evidence of its activity. Other similar faults affecting the western Peloponnese can be envisaged with a similar procedure. Additionally, the seismic history and surface

  9. The Tyrrhenian Basin: fault activity migration, focusing of deformation, break up, magmatism and fast mantle exhumation

    NASA Astrophysics Data System (ADS)

    Ranero, Cesar R.; Sallarés, Valenti; Vendrell, Montserrat G.; Prada, Manuel; Grevemeyer, Ingo; Zitellini, Nevio

    2015-04-01

    We present a new interpretation of the creation of the geological domains and the processes forming the Tyrrhenian basin by rifting of Cratonic Variscan lithosphere. The basin is not presently extending, but its crustal structure preserves information of the temporal evolution of rifting processes. Our work is based on the tectonic structure and stratigraphy of over 3000 km of calibrated multichannel seismic data and full coverage multibeam bathymetry of the basin. From these data circa 2000 km are new and about 1000 are vintage data. The seismic data are used to understand the formation of the domains (continental, backarc magmatism, exhumed mantle) defined with our recently published, under review, or submitted 5 across-the-basin wide-angle reflection and refraction transects. The 5 transects provide the Vp distribution of the crust and upper mantle. This information has allowed defining the petrological nature and distribution of the geological domains, and to infer the importance of magmatism in the rifting process, to constrain the location of break up and the expanse of the region of mantle exhumation. The seismic reflection images have been interpreted to map in time and space the evolution of the deformation across the basin. We analyzed the tectonic structure and mapped the calibrated stratigraphy across the basin to understand the temporal evolution and styles of faulting processes. The stratigraphy provides also constraints on the rates at which the different processes of extension, magmatism, break up and mantle exhumation have occurred. The basin has opened with different extension factors from north to south. The northern region stopped opening after a relatively low extension factors. Towards the south extension increased up to full crustal separation. Here extension in some areas was coeval with abundant magmatism. Changing in the locus of faulting and rates of extension led to break up and to a surprisingly fast mantle exhumation. Subsequent

  10. Measurement of short-base deformations in one of the regions of active fracturing in the Hanoi depression (the Socialist Republic of Vietnam)

    NASA Astrophysics Data System (ADS)

    Karmaleeva, R. M.; Yem, Nguyen Trong; Tu, Nguyen Dinh; Quoc, Le Minh; Chan Quoc, Hung

    1992-02-01

    Observations of deformation processes were carried out in one of the regions of active fracturing in the territory of the Hanoi depression, with the purpose of determining the rates of recent crustal movements during time intervals of about 1 yr to several years. The measurements were conducted with deformometers and hydrostatic levellers installed in a 5 m deep trench. The observation data for the 1985-1988 period indicate a high tectonic activity in the region studied. The horizontal deformation rates are (1-10) 10 -5/yr, and the vertical rates are 10 -4-10 -3/yr. Spectral characteristics of recorded processes have been obtained as well as meteorological effects.

  11. Stories from the Front.

    ERIC Educational Resources Information Center

    Melnick, Blake

    2002-01-01

    Shares some of the author's personal experiences from the "front line" to illustrate the potential of computer-supported learning environments. Concludes that technology, if used in conjunction with sound pedagogy, allows students to tep outside the confines of the traditional classroom and school structure and take responsibility for both their…

  12. 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.

  13. 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.

  14. Activation and deformation of immobilized lipase on self-assembled monolayers with tailored wettability.

    PubMed

    Chen, Peng-Cheng; Huang, Xiao-Jun; Xu, Zhi-Kang

    2015-05-28

    In this work, lipase from Candida rugosa (CRL) was immobilized on self-assembled monolayers (SAMs) with various wettabilities ranging from highly hydrophilic to highly hydrophobic by adsorption in order to clearly elucidate the interfacial activation character of lipases. The SAMs were made of 11-hydroxyundecane-1-thiol and 1-dodecanethiol. The adsorption behavior was monitored in situ by quartz crystal microbalance with dissipation (QCM-D), and the enzyme binding constants indicated a stronger affinity between CRL and more hydrophobic surfaces. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the morphologies of the adsorbed lipases. Amide I band attenuated total reflection/Fourier transformed infrared (ART/FTIR) spectroscopy showed an increasing fraction of intermolecular β-sheet content on surfaces with higher hydrophilicities. Moreover, liquid chromatography (LC) verified that the activity of CRL adsorbed on a hydrophobic surface was higher than that of CRL adsorbed on a hydrophilic surface. This work related the enzyme activity to the substrate properties, adsorption behavior, distribution, and morphology of lipases, helping to achieve the external control of both the immobilization process and enzyme utilization. PMID:25929434

  15. 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

  16. Swim stress, motion, and deformation of active matter: effect of an external field.

    PubMed

    Takatori, Sho C; Brady, John F

    2014-12-21

    We analyze the stress, dispersion, and average swimming speed of self-propelled particles subjected to an external field that affects their orientation and speed. The swimming trajectory is governed by a competition between the orienting influence (i.e., taxis) associated with the external (e.g., magnetic, gravitational, thermal, nutrient concentration) field versus the effects that randomize the particle orientations (e.g., rotary Brownian motion and/or an intrinsic tumbling mechanism like the flagella of bacteria). The swimmers' motion is characterized by a mean drift velocity and an effective translational diffusivity that becomes anisotropic in the presence of the orienting field. Since the diffusivity yields information about the micromechanical stress, the anisotropy generated by the external field creates a normal stress difference in the recently developed "swim stress" tensor [Takatori, Yan, and Brady, Phys. Rev. Lett., 2014]. This property can be exploited in the design of soft, compressible materials in which their size, shape, and motion can be manipulated and tuned by loading the material with active swimmers. Since the swimmers exert different normal stresses in different directions, the material can compress/expand, elongate, and translate depending on the external field strength. Such an active system can be used as nano/micromechanical devices and motors. Analytical solutions are corroborated by Brownian dynamics simulations. PMID:25330273

  17. 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

  18. 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

  19. View of portion of the front entry on the front ...

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

    View of portion of the front entry on the front (west) side of the Mueller house, looking northeast. Sheds are in the background. - Ernst Mueller House, 6563 East Avenue, Rancho Cucamonga, San Bernardino County, CA

  20. 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

  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. 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.

  3. 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.

  4. Front Range Report, Abstracts

    NASA Astrophysics Data System (ADS)

    Spence, William

    The second regional conference of the Front Range Branch, AGU, was attended by more than 80 professionals and some 20 outstanding high school students. The conference included 2 days of interdisciplinary talks, and lots of discussion, that primarily were keyed to geophysical studies of Colorado, Wyoming, and New Mexico. Other talks reported on nonregional, and sometimes global, studies being done by geophypsicists of the Front Range region.Topics included tectonics of the Front Range and the Colorado Plateau, pollution of the Arkansas and Mississippi rivers, and a supreme polluting event that caused the late-Cretaceous extinctions. Other notable talks were on toxic cleanup, microburst (wind shear) detection at U.S. airports, and other meteorological studies. Several talks treated the audience to the excitement of new work and surprise discoveries. The meeting was multimedia, including the playing of two videos through a projection TV and the playing of a fascinating tape between an airport control tower and incoming pilots during a severe microburst event.

  5. 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.

  6. 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.

  7. Radiative thermal conduction fronts

    NASA Astrophysics Data System (ADS)

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

    1990-07-01

    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.

  8. 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.

  9. Active Deformation along the Southern End of the Tosco-Abreojos Fault System: New Insights from Multibeam Swath Bathymetry

    NASA Astrophysics Data System (ADS)

    Michaud, François; Calmus, Thierry; Ratzov, Gueorgui; Royer, Jean-Yves; Sosson, Marc; Bigot-Cormier, Florence; Bandy, William; Mortera Gutiérrez, Carlos

    2011-08-01

    The relative motion of the Pacific plate with respect to the North America plate is partitioned between transcurrent faults located along the western margin of Baja California and transform faults and spreading ridges in the Gulf of California. However, the amount of right lateral offset along the Baja California western margin is still debated. We revisited multibeam swath bathymetry data along the southern end of the Tosco-Abreojos fault system. In this area the depths are less than 1,000 m and allow a finer gridding at 60 m cell spacing. This improved resolution unveils several transcurrent right lateral faults offsetting the seafloor and canyons, which can be used as markers to quantify local offsets. The seafloor of the southern end of the Tosco-Abreojos fault system (south of 24°N) displays NW-SE elongated bathymetric highs and lows, suggesting a transtensional tectonic regime associated with the formation of pull-apart basins. In such an active tectonic context, submarine canyon networks are unstable. Using the deformation rate inferred from kinematic predictions and pull-apart geometry, we suggest a minimum age for the reorganization of the canyon network.

  10. 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

  11. 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

  12. 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

  13. Late Quaternary deformation rates in the Pamir-Tian Shan collision zone, NW China

    NASA Astrophysics Data System (ADS)

    Thompson, J. A.; Li, T.; Burbank, D. W.; Chen, J.; Bookhagen, B.; Bufe, A.; Yang, H.

    2014-12-01

    Deformation of the Pamir and Tian Shan orogens initiated during the Neogene as a result of the Indo-Eurasian colision. The arid landscape in the western Tarim Basin, NW China, preserves suites of fluvial terraces crossing many of the Late Neogene active structures, creating fault and fold scarps. We present new deformation rates on five faults and folds, which in combination with previous studies, highlight the spatial and temporal patterns of deformation during the Late Quaternary. Suites of terraces spanning ~130 ka to ~8 ka document the basinward propagation of deformation, with the fastest rates currently located on actively deforming structures at the interface of the Pamir-Tian Shan orogens. During the last ~6 ka, the Pamir deformation front has stepped north, creating the Mingyaole South Thrust, which produced the 1985 M7.4 Wuqia Earthquake. Trenching on several sections of this fault reveal an earthquake reoccurence interval of ~1.0 ky. The Late Quaternary deformation rates on faults and folds along the Pamir-Tian Shan collision zone indicate that the locus of deformation was not concentrated on a single structure, but rather was concurrently distributed across a zone of structures. Despite numerous structures accommodating the shortening and the locus of deformation shifting throughout the Late Quaternary, the total shortening across the Pamir-Tian Shan collision zone since ~0.35 Ma has remained steady and is approximately equal to the current geodetic rate of 6-9 mm/a, as well as broadly similar to preliminary InSAR-derived deformation rates across the region.

  14. 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.

  15. Crustal thickening drives arc front migration

    NASA Astrophysics Data System (ADS)

    Karlstrom, L.; Lee, C.; Manga, M.

    2012-12-01

    The position of active volcanism relative to the trench in arcs depends on melt focusing processes within the mantle wedge and the geometric parameters of subduction. Arc front migration has been observed in relic (Sierra Nevada, Andes) as well as active (Cascades) arcs, sometimes with cycles of retreat and return of the front towards the trench over millions of years. Other arcs, particularly where backarc extension dominates, exhibit a more stationary front in time relative to the trench. In addition, crustal indices of magmatism as measured by the ratio of trace elements La/Yb or isotopes 87}Sr/{86Sr covary with arc front migration (e.g., Haschke et al., 2002). Arc front migration is commonly attributed to variation in dip angle of the downgoing slab, delamination of overthickened crust, or to subduction erosion. Here we present an alternative hypothesis. Assuming mantle wedge melting is a largely temperature-dependant process, the maximum isotherm in the wedge sets arc front location. Isotherm location depends on slab angle, subduction velocity and wedge thermal diffusivity (England and Katz, 2010). It also depends on crustal thickness, which evolves as melt is transferred from the wedge to the crust. Arc front migration can thus occur purely through magmatic thickening of crust. Thickening proceeds through intrusive as well as extrusive volcanism, modulated by tectonics and surface erosion. Migration rate is set by the mantle melt flux into the crust, which decreases as thickening occurs. Thus slab angle need not change, and in the absence of other contribution processes front location and crustal thickness have long-time steady state values. We develop an analytic model of this process that produces migration rates consistent with published data and explains arc fronts that do not move (dominated by extension, such as in the case of intra-oceanic arcs). We present new geochemical and age data from the Peninsular Ranges Batholith that are also consistent with

  16. Crustal thickening drives arc front migration

    NASA Astrophysics Data System (ADS)

    Karlstrom, Leif; Lee, Cin-Ty; Manga, Michael

    2014-05-01

    The location of volcanic arcs, relative to the trench evolves over time. Arc front migration has been observed in relic (Sierra Nevada, Andes) as well as active (Cascades) arcs, sometimes with cycles of retreat and return of the front towards the trench over millions of years. Other arcs, particularly where back-arc extension dominates, migrate more slowly, if at all. Coupled with arc migration there are systematic changes in the geochemistry of magmas such as the ratio of trace elements La/Yb and 87Sr/86Sr isotopes (e.g., Haschke et al., 2002). The position of active volcanic arcs relative to the trench is controlled by the location where melt is generated in the mantle wedge, in turn controlled by the geometry of subduction, and the processes that focus rising melt. Arc front migration is commonly attributed to variation in dip angle of the downgoing slab, delamination of overthickened crust, or to subduction erosion. Here we present an alternative hypothesis. Assuming mantle wedge melting is a largely temperature-dependant process, the maximum isotherm in the wedge sets arc front location. Isotherm location depends on slab angle, subduction velocity and wedge thermal diffusivity (England and Katz, 2010). It also depends on crustal thickness, which evolves as melt is transferred from the wedge to the crust. Arc front migration can thus occur purely through magmatic thickening of crust and lithosphere. Thickening rate is determined by the mantle melt flux into the crust, modulated by tectonics and surface erosion. It is not steady in time, as crustal thickening progressively truncates the mantle melt column and eventually shuts it off. Thus slab angle need not change, and in the absence of other contribution processes front location and crustal thickness have long-time steady state values. We develop a quantitative model for arc front migration that is consistent with published arc front data, and explains why arc fronts do not move when there is extension, such

  17. 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.

  18. 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

  19. 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

  20. 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

  1. Combustion front propagation in underground coal gasification

    SciTech Connect

    Dobbs, R.L. II; Krantz, W.B.

    1990-10-01

    Reverse Combustion (RC) enhances coal seam permeability prior to Underground Coal Gasification. Understanding RC is necessary to improve its reliability and economics. A curved RC front propagation model is developed, then solved by high activation energy asymptotics. It explicitly incorporates extinction (stoichiometric and thermal) and tangential heat transport (THT) (convection and conduction). THT arises from variation in combustion front temperature caused by tangential variation in the oxidant gas flux to the channel surface. Front temperature depends only weakly on THT; front velocity is strongly affected, with heat loss slowing propagation. The front propagation speed displays a maximum with respect to gas flux. Combustion promoters speed front propagation; inhibitors slow front propagation. The propagation model is incorporated into 2-D simulations of RC channel evolution utilizing the boundary element method with cubic hermetian elements to solve the flow from gas injection wells through the coal to the convoluted, temporally evolving, channel surface, and through the channel to a gas production well. RC channel propagation is studied using 17 cm diameter subbituminous horizontally drilled coal cores. Sixteen experiments at pressures between 2000 and 3600 kPa, injected gas oxygen contents between 21% and 75%, and flows between 1 and 4 standard liters per minute are described. Similarity analysis led to scaling-down of large RC ({approx}1 m) to laboratory scale ({approx}5 cm). Propagation velocity shows a strong synergistic increase at high levels of oxygen, pressure, and gas flow. Char combustion is observed, leaving ash-filled, irregularly shaped channels. Cracks are observed to penetrate the char zone surrounding the channel cores. 69 refs., 54 figs., 4 tabs.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. About Shape of an Interplanetary Shock Front.

    NASA Astrophysics Data System (ADS)

    Petukhov, Ivan; Petukhov, Stanislav

    The form of an interplanetary shock front has been investigated by the statistical method. Results of determination the components of normals to the interplanetary shock fronts obtained from data of ACE experiment during from 1998 to 2003 years (about 200 measurements) are used. North-south asymmetry of shock amount about 15% is revealed. Possibly, it is caused by more activity of the north semi-sphere of the Sun. East-west asymmetry of shock area are obtained. At probability 95% values of asymmetry more 0.53 and less 0.65 at most probability 0.59. Here asymmetry is ratio west part of area to whole area of shock front. Possibly, it is formed at propagation of a shock in interplanetary space. The reason of asymmetry may be self-generation turbulence by the accelerated particles which influences on velocity of shock propagation.

  9. Madelung deformity.

    PubMed

    Ghatan, Andrew C; Hanel, Douglas P

    2013-06-01

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

  10. Surface Deformation Analysis of the Active Faults revealed by InSAR Observations and Geodetic Data in Southern Part of the Taitung Longitudinal Valley, Eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Tung, H.; Chen, H. Y.; Hu, J. C.

    2009-04-01

    The NNE-striking Longitudinal Valley Fault (LVF) in eastern Taiwan is an extremely active inverse fault, which is considered as a collision boundary between the Eurasian and the Philippine Sea plates. The fault segments of the LVF demonstrate different slip behaviors, especially in the southern segment of the LVF. The deformation is partitioned by the strike-slip (Lichi fault segment) and the reverse faulting (Luyeh segment). Thus we investigate crustal deformation pattern along the southern LVF by using SAR interferometry and precise leveling data. The SAR data of the Longitudinal Valley area were collected by ERS-1, ERS-2 and Envisat satellite of the European Space Agency in both descending (track: 232; frame: 3141) and ascending (track: 311; frame: 459) orbits. However, this area is so heavily vegetated that high coherence area is limited in the Taitung City and good interfergrams with better coherence are limited to short time span and small perpendicular baseline pairs. Therefore we made three stacking image from the higher coherence interferograms representing deformation interval from 1995-1996, 1996-1998 and 2006-2008 separately. These three results show a same relative subsidence between Luyeh fault and Lichi fault, which is consistent with leveling data measured that time. Besides, we also used the PSInSAR technique to trace the discrete points that were minimally affected by the decorrelation of radar signals through time. Finally we constrain the deformation map based on PSInSAR with leveling data for better understanding the deformation patterns in the southern Longitudinal Valley area.

  11. Ground deformation associated with post-mining activity at the French-German border revealed by novel InSAR time series method

    NASA Astrophysics Data System (ADS)

    Samsonov, Sergey; d'Oreye, Nicolas; Smets, Benoît

    2013-08-01

    We present a novel methodology for integration of multiple InSAR data sets for computation of two dimensional time series of ground deformation. The proposed approach allows combination of SAR data acquired with different acquisition parameters, temporal and spatial sampling and resolution, wavelength and polarization. Produced time series have combined coverage, improved temporal resolution and lower noise level. We apply this methodology for mapping coal mining related ground subsidence and uplift in the Greater Region of Luxembourg along the French-German border. For this we processed 167 Synthetic Aperture Radar ERS-1/2 and ENVISAT images acquired between 1995 and 2009 from one ascending (track 29) and one descending (track 337) tracks and created over five hundred interferograms that were used for time series analysis. Derived vertical and east-west linear deformation rates show with remarkable precision a region of localized ground deformation located above and caused by mining and post-mining activities. Time series of ground deformation display temporal variability: reversal from subsidence to uplift and acceleration of subsidence in the vertical component, and horizontal motion toward the center of the subsidence on the east-west component. InSAR results are validated by leveling measurements collected by the French Geological Survey (BRGM) during 2006-2008. We determined that deformation rate changes are mainly caused by water level variations in the mines. Due to higher temporal and spatial resolution the proposed space-borne method detected a larger number of subsidence and uplift areas in comparison to leveling measurements restricted to annual monitoring of benchmark points along roads. We also identified one deformation region that is not precisely located above the mining sites. Comparison of InSAR measurements with the water levels measured in the mining pits suggest that part of the water that filled the galleries after termination of the

  12. Ground Deformation Associated With Post-Mining Activity at the French-German Border Revealed by Multidimensional Time Series Analysis of SAR Data Acquired in Various Orbital Geometries

    NASA Astrophysics Data System (ADS)

    Smets, B.; Samsonov, S. V.; d'Oreye, N.

    2012-12-01

    We present the application of an innovative methodology for producing multidimensional time series of ground deformation from satellite radar data acquired by sensors with various acquisition geometry, ground resolution, and wave band (Samsonov and d'Oreye, Resubmitted). This technique is based on the Small Baseline Subset (SBAS) method that is modified to produce horizontal and vertical time series of ground deformation. Produced time series have combined coverage, improved temporal resolution and lower noise level. We apply this methodology for mapping coal mining related ground subsidence and heave in the Greater Region of Luxembourg along the French-German border. For this we processed 167 Synthetic Aperture Radar ERS-1/2 and ENVISAT images acquired between 1995 and 2009 from one ascending (track 29) and one descending (track 337) tracks and created over five hundred interferograms that were used for time series analysis. Produced vertical and east-west linear deformation rates show with remarkable precision region of localized ground deformation located above and caused by mining and post-mining activities. Time series of ground de- formation display temporal variability: reversal from subsidence to uplift and acceleration of subsidence on the vertical component and horizontal motion towards the center of the subsidence on the east-west component. InSAR results are successfully validated by leveling measurements performed by the French Geological Survey (BRGM) during 2006-2008. We determined that deformation rate changes are mainly caused by water level variations in the mines. Due to higher temporal and spatial resolution the proposed space-born method detected a larger number of subsidence and uplift areas in comparison to leveling measurements restricted to annual monitoring of benchmark points along roads. We also identified deformation regions that are not precisely located above the mining sites. Comparison of InSAR measurements with the water levels

  13. 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

  14. FACILITY 209, SINGLESTORY DUPLEX, FRONT OBLIQUE VIEW OF FRONT FROM ...

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

    FACILITY 209, SINGLE-STORY DUPLEX, FRONT OBLIQUE VIEW OF FRONT FROM CENTER DRIVE, FACING SW. - U.S. Naval Base, Pearl Harbor, Housing Area 1, Single Story Duplex Type, Bounded by Kamehameha Highway, Plantation Drive, South Avenue, Pearl City, Honolulu County, HI

  15. 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

  16. Experimental Deformation of Magnetite

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  17. 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

  18. 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

  19. 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

  20. 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.

  1. MMS Observations of Dipolarization Fronts

    NASA Astrophysics Data System (ADS)

    Hwang, K. J.; Goldstein, M. L.; Sibeck, D. G.; Ashour-Abdalla, M.; Nakamura, R.; Burch, J. L.; Torbert, R. B.; Moore, T. E.; Ergun, R. E.; Pollock, C. J.; Mauk, B.; Fuselier, S. A.

    2015-12-01

    We present MMS observations of dipolarization fronts. Dipolarization fronts commonly observed in Earth's plasma sheet are characterized by intense gradients in the current sheet-normal component of the magnetic field and plasma/magnetic pressure across the front. These fronts are often embedded within fast earthward flows, i.e., bursty bulk flows. Analysis using data from all four spacecraft shows the presence of both typical and atypical dipolarization fronts. Typically dipolarization fronts propagate earthward and their normals point radially inward, however, we have identified dipolarization fronts propagating tailward with normals pointing significantly away from the radial direction. Atypical dipolarization fronts observed on 7 May 2015 and 21 July 2015 are preceded or accompanied by a rapid decrease in the Bx or By components of the magnetic field. These decreases indicate that the magnetotail is first thinning and then thickening. The resulting magnetic pile-up can cause the local Bz to increase rapidly, indicating propagation tailward, as observed. These new high time resolution field and plasma observations from MMS provide exciting new insights about the dynamical changes of magnetotail topology.

  2. 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.

  3. 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.

  4. 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.

  5. The sequence of moderate-size earthquakes at the junction of the Ligurian basin and the Corsica margin (western Mediterranean): The initiation of an active deformation zone revealed?

    NASA Astrophysics Data System (ADS)

    Larroque, Christophe; Delouis, Bertrand; Sage, Françoise; Régnier, Marc; Béthoux, Nicole; Courboulex, Françoise; Deschamps, Anne

    2016-04-01

    A new seismically active zone is found in the southern part of the Ligurian basin, 80-km west of Corsica (western Mediterranean). The activity began in February 2011 with a foreshock (ML 4) and a mainshock (ML 5.3) 5 days later, followed by numerous aftershocks. We first analyze the fore- and mainshock in detail. We compare the results obtained using classical methods (linear location in a 1D medium and focal mechanisms from P and S polarities) and new approaches (non-linear location in a 3D medium and waveform modeling for determining the seismic moment and the focal mechanism). Both methods provided similar results for location, depth (in the range of 6-13 km) and focal mechanisms, which reveal reverse faulting with nodal planes oriented N-S and NE-SW. We then locate 27 of the aftershocks in the 3D model and find a 10-km-long NE-SW alignment with a depth between 7 and 16 km. In 2012 and 2013, three other moderate-size events (ML 3.8, 4 and 4.5) occurred and confirm that this zone is still active. The epicentral area is located in the oceanic domain of the Ligurian Basin. From analysis of the bathymetry and high-resolution multi-channel seismic profiles, no morphologic anomaly at surface and no inherited fault in the shallow ~ 4 km depth were imaged, which suggest that no significant deformation occurred in the area since 5 Ma. Thus, the structure(s) activated during the 2011-2013 sequence remain unknown. In light of these results, we point out a notable difference on both sides of the Ligurian Basin: the northern margin, close to the alpine chain, suffered strong earthquakes and large cumulated deformation since 5 Ma, while the southern margin, close to the Corsica-Sardinia continental block, is poorly deformed since 5 Ma.

  6. New Perspectives on Intermountain Cyclones and Cold Fronts

    NASA Astrophysics Data System (ADS)

    Steenburgh, W. J.; West, G.; Neuman, C.; Shafer, J.; Jeglum, M.; Bosart, L. F.; Lee, T.

    2011-12-01

    The topography in and around the Intermountain West strongly affects the genesis, migration, and lysis of extratropical cyclones and cold fronts. In this presentation, we summarize new perspectives on Intermountain cyclone and cold-front evolution derived from recent climatological, observational, and modeling studies based on high-density observations and high-resolution reanalyses and numerical simulations. Recent high-resolution reanalyses show that Intermountain cyclone activity is greatest in two distinct regions. The first, which we call the Great Basin cyclone region, extends northeastward from the southern high Sierra to the Great Salt Lake Basin of northwest Utah. The second, which we call the Canyonlands cyclone region, lies over the upper Colorado River Basin of southeast Utah, a lowland region between the mountains and plateaus of central Utah and the Colorado Rockies. Composites of strong Intermountain cyclones generated in cross-Sierra (210-300°) 500-hPa flow show that cyclogenesis is preceeded by the development of the Great Basin Confluence Zone (GBCZ), a regional airstream boundary that extends downstream from the Sierra Nevada. Cyclogenesis occurs along the GBCZ as large-scale ascent develops over the Intermountain West in advance of an approaching upper-level trough. Flow splitting around the high Sierra and the presence of low-level baroclinity along the GBCZ suggest that Intermountain Cyclogenesis might be better conceptualized from a potential vorticity perspective than from traditional quasigeostrophic models of lee cyclogenesis. Surface observations indicate that the frequency of strong cold-frontal passages increases dramatically from the Cascade-Sierra Mountains to northern Utah, suggesting that the Intermountain West is a frequent cold-frontal breeding ground. Two case studies help illustrate the mechanisms contributing to these strong cold-frontal passages. During the 2002 Tax Day Cyclone, strong contraction (i.e., deformation and

  7. Long- and short-term deformation along the active northern margin of the hyblean plateau (se sicily) from multidisciplinary data: evidence for a new potential seismogenic source

    NASA Astrophysics Data System (ADS)

    Bonforte, Alessandro; Catalano, Stefano; Maniscalco, Rosanna; Pavano, Francesco; Romagnoli, Gino; Sturiale, Giovanni; Tortorici, Giuseppe

    2014-05-01

    A geologic and geodetic integrated analysis of the northern margin of the Hyblean Plateau (SE Sicily) has been carried out in order to test the relation of the active deformation, recorded by GPS data, and the long-term tectonic evolution, recorded by structural and morphological data, with potential seismogenic sources of the region, where high level (MCS I0 = X - XI) historical seismicity occurred. To date, seismotectonic models have alternatively related the main seismogenic sources to the incipient rifting that reactivated the Malta Escarpment in the Ionian off-shore or to the still active NW-SE trending Nubia-Eurasia convergence, that remobilized the northern tectonic boundary of the Hyblean Plateau. In this region, the new data reveal that the active deformation can be framed in the flexural tectonics developed during the late stages of the Nubia-Eurasia plate convergence. Geodetic and geological data provide a coherent kinematic picture that is compatible with the occurrence of a blind ramp thrust along the NW margin of the Hyblean Plateau. This study demonstrates that the onshore seismicity of the Hyblean region can be confidently referred to active compressional dynamics. Additionally, our data candidate the inferred blind thrust, located to the south of the Scordia-Lentini graben, as a major potential seismogenic source that might be considered in interpreting the historical seismicity of the region.

  8. 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

  9. Flame front as hydrodynamic discontinuity

    NASA Astrophysics Data System (ADS)

    Fukumoto, Yasuhide; Abarzhi, Snezhana

    2012-11-01

    We applied generalized Rankine-Hugoniot conditions to study the dynamics of unsteady and curved fronts as a hydrodynamic discontinuity. It is shown that the front is unstable and Landau-Darrieus instability develops only if three conditions are satisfied (1) large-scale vorticity is generated in the fluid bulk; (2) energy flux across the front is imbalanced; (3) the energy imbalance is large. The structure of the solution is studied in details. Flows with and without gravity and thermal diffusion are analyzed. Stabilization mechanisms are identified. NSF 1004330.

  10. Qu'est-ce que le front des orogènes? L'exemple de l'orogène pyrénéen

    NASA Astrophysics Data System (ADS)

    Lacombe, Olivier; Mouthereau, Frédéric

    1999-12-01

    The concept of 'orogenic front' is discussed theoretically and on the basis of the Pyrenees example. Depending on the geological criterion, a morphologic front (mountain front), a thrust-wedge front, a reactivation front and a deformation front can be distinguished. The classical, critical thrust wedge made of cover material, moving above a shallow décollement, is considered as the upper part of a larger, steady-state wedge above a shallow basal décollement connected to a deeper one (lower crust?) and where both sedimentary and basement units are involved: its front corresponds to both the mountain front and the thrust-wedge front, that is the front of the allochthonous nappes. Transmission of orogenic stresses (which decrease exponentially with increasing distance to the belt), responsible for intraplate deformations, especially inversion of preexisting extensional features, over a distance greater than 1 000 km away from the belt, require both a relatively rigid lithosphère and a crustal decoupling far in the foreland. The outermost reactivated and/or inverted structure thus locates the reactivation front, which limits a low-slope and low-strength foreland area that is not yet at steady-state and therefore cannot be discussed in terms of critical taper wedge. An outermost deformation front, limiting the part of the foreland where orogenic stresses have only been recorded by microstructures without significant displacements, can also be considered.

  11. 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

  12. 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.

  13. Deformation textures in Fe{sub 3}Al alloys: An assessment of dominant slip system activity in the 900--1325 K temperature range of hot working

    SciTech Connect

    Kad, B.K.; Schoenfeld, S.E.; Asaro, R.J.; McKamey, C.G.; Sikka, V.K.

    1997-04-01

    A combination of numerical and experimental methodologies have been employed to study deformation textures in Fe{sub 3}Al alloys produced entirely by crystallographic shears on the <111>{l_brace}110{r_brace} + <111>{l_brace}112{r_brace}, <100>{l_brace}011{r_brace} and <100>{l_brace}001{r_brace} slip systems, respectively. Numerical simulations indicate that both <111>{l_brace}110{r_brace} + <111>{l_brace}112{r_brace} and <100>{l_brace}011{r_brace} slip systems produce a reasonably strong texture, while <100>{l_brace}001{r_brace} induces no texture over the initial random configuration. Experimental texture measurements on samples deformed at deformation rates of 10{sup {minus}3}--10{sup 1} s{sup {minus}1} by forging, rolling and extrusion in the 925--1325 K temperature range, of the B2 structure regime, agree well with the predicted textures for the <111>{l_brace}110{r_brace} + <111>{l_brace}112{r_brace} slip system activation. These results appear to be in disagreement with prior transmission electron microscopy (TEM) observations that support the activation of <100>{l_brace}011{r_brace} and <100>{l_brace}001{r_brace} slip systems. Possible sources of discrepancies are elucidated. Finally, the loss of ductility in fully recrystallized microstructures is explained by textural reorganizations that are likely to impose larger normal stresses on the dominant {l_brace}100{r_brace} fracture planes.

  14. 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

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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, WSTZ, calculated using the cooperative shear model, is equivalent to the activation energy for β-relaxation, Eβ. This result suggested that the fundamental process for STZ activation is the mechanically activated β-relaxation. Since the Eβ value and the glass transition temperature Tg of BMGs have a linear relation, that is, because Eβ ≈ 26RTg, the composition of the BMG determines the ease with which the STZ can be activated. Enthalpy relaxation experiments revealed that the BMG Zr50Cu40Al10 when deformed by high-pressure torsion (HPT) has a lower Eβ 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 WSTZ 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 Eβ (or WSTZ) and result in improvements in the mechanical properties of the BMG.

  17. 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.

  18. 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

  19. Deformation rates and localization of an active fault system in relation with rheological and frictional slip properties: The Corinth Rift case

    NASA Astrophysics Data System (ADS)

    El Arem, S.; Lyon-Caen, H.; Bernard, P.; Garaud, J. D.; Rolandone, F.; Briole, P.

    2012-04-01

    The Gulf of Corinth in Greece has attracted increasing attention because of its seismically active complex fault system and considerable seismic hazard. It is one of the most active extensional regions in the Mediterranean area. However, there are still open questions concerning the role and the geometry of the numerous active faults bordering the basin, as well as the mechanisms governing the seismicity. The Corinth Rift Laboratory (CRL http://crlab.eu) project is based on the cooperation of various European institutions that merge their efforts to study fault mechanics and related hazards in this natural laboratory with 10 destructive earthquakes per century (Magnitude > 6), among which 4 in the selected region of CRL. This active rift continues to open over 10-12 Km of width at a rate of 1:5 cm=yr. Most of the faults of the investigated area are in their latest part of cycle, so that the probability of at least one moderate to large earthquake (Magnitude = 6 to 6:7) is very high within a few decades. In the first part of this work, two-dimensional finite element models of a fault system is considered to estimate the effects of the crust rheological parameters on the stress distribution, the horizontal and vertical deformation in the vicinity of the faults, and the plastic deformation localization. We consider elasto-visco-plastic rheology with a power law viscosity for dislocation creep modelling and the Drucker-Prager yield criterion for plasticity. We investigate the rheological properties of the crust and examine their compatibility with both horizontal and vertical GPS observations recorded during campaigns conducted in the last twenty years. The second part is devoted to simulations involving rate and slip history friction laws for earthquake occurence prediction and seismogenic depth approximation. The case of a single fault is examined first, then two active faults are considered to highlight the effect of their interactions on the seismic cycle

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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)

  5. Active tectonics of the Binalud Mountains, a key puzzle segment to describe Quaternary deformations at the northeastern boundary of the Arabia-Eurasia collision

    NASA Astrophysics Data System (ADS)

    Shabanian, Esmaeil; Bellier, Olivier; Siame, Lionel L.; Abbassi, Mohammad R.; Leanni, Laetitia; Braucher, Régis; Farbod, Yassaman; Bourlès, Didier L.

    2010-05-01

    In northeast Iran, the Binalud Mountains accommodate part of active convergence between the Arabian and Eurasian plates. This fault-bounded mountain range has been considered a key region to describe Quaternary deformations at the northeastern boundary of the Arabia-Eurasia collision. But, the lack of knowledge on active faulting hampered evaluating the geological reliability of tectonic models describing the kinematics of deformation in northeast Iran. Morphotectonic investigations along both sides of the Binalud Mountains allowed us to characterize the structural and active faulting patterns along the Neyshabur and Mashhad fault systems on the southwest and northeast sides of the mountain range, respectively. We applied combined approaches of morphotectonic analyses based on satellite imageries (SPOT5 and Landsat ETM+), STRM and site-scale digital topographic data, and field surveys complemented with in situ-produced 10Be exposure dating to determine the kinematics and rate of active faulting. Three regional episodes of alluvial surface abandonments were dated at 5.3±1.1 kyr (Q1), 94±5 kyr (Q3), and 200±14 kyr (S3). The geomorphic reconstruction of both vertical and right-lateral fault offsets postdating these surface abandonment episodes yielded Quaternary fault slip rates on both sides of the Binalud Mountains. On the Neyshabur Fault System, thanks to geomorphic reconstructions of cumulative offsets recorded by Q3 fan surfaces, slip rates of 2.7±0.8 mm/yr and 2.4±0.2 mm/yr are estimated for right-lateral and reverse components of active faulting, respectively. Those indicate a total slip rate of 3.6±1.2 mm/yr for the late Quaternary deformation on the southwest flank of the Binalud Mountains. Reconstructing the cumulative right-lateral offset recorded by S3 surfaces, a middle-late Quaternary slip rate of 1.6±0.1 mm/yr is determined for the Mashhad Fault System. Altogether, our geomorphic observations reveal that, on both sides of the Binalud Mountains

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. Self-turbulizing flame fronts

    NASA Astrophysics Data System (ADS)

    Clavin, P.; Searby, G.

    A heuristic derivation of a flame front model is presented that takes into account the effects of gravity, nonlinear effects introduced by advection of the front, and gradients in the tangential component of the flow. A local equation is defined to relate the normal flame speed to the upstream gas flow characteristics. Jump conditions are obtained from an asymptotic analysis of the local structure of the wrinkled flame in order to address the hydrodynamic problem possed by the front being treated as a free boundary between fresh and burnt gases. The expression for the jump conditions is defined in Fourier space. The model extends the equations defined in Fourier space. The model extends the equations defined by Sivashinsky (1977) to cover the effects of gas expansion.

  13. 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.

  14. The influence of stepwise deformation of aluminum-magnesium alloy upon its electrical conduction

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Zolotov, A. E.; Gasanov, M. F.; Zheltov, M. A.; Greben'kov, O. V.

    2016-04-01

    The influence of stepwise deformation upon the electrical conduction of the AlMg6 aluminum-magnesium alloy is investigated experimentally. It is found that the nucleation and development of single deformation bands causing stepwise deformation increase the specific electric resistance of the alloy on average by 2-3%. It is supposed that the main mechanism of an increase in the electric resistance in the deformation band is growth of the deformation vacancy concentration, which is connected with intensive dislocation multiplication in the deformation band front.

  15. 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.

  16. 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.

  17. 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.

  18. [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

  19. Late Quaternary slip rates and paleoearthquakes along the Yabrai range-front fault in the southern Gobi-Alashan block

    NASA Astrophysics Data System (ADS)

    Yu, Jingxing; Zheng, Wenjun; Lei, Qiyun; Shao, Yanxiu; Ge, Weipeng

    2014-05-01

    Study on the active faults of the southern Gobi-Alashan block is significant to understand the tectonic deformation processes associated with the Tibetan Plateau and Ordos block. With this knowledge in mind, the present study aims to answer what the major process is governing the tectonic deformation and the structural relationships between Gobi-Alashan and adjacent regions. Since this area was featured by late Quaternary active tectonics, the activities and paleoearthquakes around the block need be studied and reconciled. So, we will focus on one of those active structures, the ranger-front fault along Yabrai Shan, to address some basic problems. Three aspects are analyzed, i.e., geomorphology, kinematic characteristics and paleoearthquakes of the range-front fault along the Yabrai Shan. By combining previous studies and Differential GPS measurements, implications of the fault for the regional tectonics has been discussed. The main conclusions are summarized as follows: This fault consists of three segments. The most active segment is in the southwest. The southwest segment is about 35 km long. Its scarp, about 1-2 m high, might be the result of the most recent event (MRE) and stretches NE60° almost the full segment. Existence of free surface indicates that the elapsed time of the last event must be not long. The middle segment is about 31 km in length. Just a single fault plane was identified along the main bounds of the Yabrai Shan, but the fault consists of several splays in the north. In contrast to the simple geometric structure of the middle segment, the northeast segment comprises several faults. Scarps of the most recent earthquake event are clear but tend not to be continued. Field investigation reveals about 0.5-1.5 m up to 2 m height. This work determined slip rates by combining fault-scarp measurements and cosmogenic exposure age dating. Study on slip rates shows that the Holocene dip-slip rate of the Yabrai fault is 0.11±0.03 mm/a. Scarp vertical

  20. Different Phases of Earthquake Cycle Reflected in GPS Measured Crustal Deformations along the Andes

    NASA Astrophysics Data System (ADS)

    Khazaradze, G.; Klotz, J.

    2001-12-01

    The South American Geodynamic Activities (SAGA) project was initiated in 1993 by the GeoForschungsZentrum together with host organizations in Argentina and Chile with the main objective of studying the kinematics and dynamics of present-day deformation processes along the central and southern Andes. Currently the SAGA network consists of 230 geodetic markers spanning more than 2000 km long distance from Peru/Chile border in the north to Cape Horn in the south. The majority of the observed crustal deformation field is relatively homogenous: roughly parallel to the plate convergence direction and decreasing in magnitude away from the deformation front. This pattern is characteristic for the \\textit{inter-seismic} phase of earthquake deformation cycle and can be explained by the elastic strain accumulation due to locking of the thrust interface between the subducting Nazca and the overriding South America plates. However, in addition to the dominant inter-seismic signal, close examination of the observed velocity field also reveals significant spatial and temporal variations, contrary to the commonly used assumption of constant deformation rates. This variation is especially pronounced for the measurements in the vicinity of the 1995 Mw8.0 Antofagasta earthquake (22{° }S-26{° }S). Here, after capturing up to 1 meters of \\textit{co-seismic} displacements associated with this event, the analysis of data obtained during the three following field campaigns (1996-1999), reveals highly time dependent deformation pattern. This can be explained by the decreasing importance of \\textit{post-seismic} effects of the Antofagasta event relative to the increasing dominance of the inter-seismic phase of subduction. Perhaps, even more interesting time dependent observations have been detected in the southern part the SAGA network (38{° }S-43{° }S).Here, after 35 years of the occurrence of the 1960 Mw9.5 Chile earthquake, we still see the continuing post-seismic effects of this

  1. 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.

  2. 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.

  3. 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)

  4. Teaching the French Popular Front.

    ERIC Educational Resources Information Center

    Wall, Irwin M.

    1987-01-01

    Examines the French Popular Front of 1936 as a vehicle to investigate the turbulent decade of the 1930s. Reviews current historiography and discusses various facets of Leon Blum's government, examining the interrelationship of major economic and political forces. Concludes that the French Left still faces Blum's dilemma of implementing socialism…

  5. Fluctuation-controlled front propagation

    NASA Astrophysics Data System (ADS)

    Ridgway, Douglas Thacher

    1997-09-01

    A number of fundamental pattern-forming systems are controlled by fluctuations at the front. These problems involve the interaction of an infinite dimensional probability distribution with a strongly nonlinear, spatially extended pattern-forming system. We have examined fluctuation-controlled growth in the context of the specific problems of diffusion-limited growth and biological evolution. Mean field theory of diffusion-limited growth exhibits a finite time singularity. Near the leading edge of a diffusion-limited front, this leads to acceleration and blowup. This may be resolved, in an ad hoc manner, by introducing a cutoff below which growth is weakened or eliminated (8). This model, referred to as the BLT model, captures a number of qualitative features of global pattern formation in diffusion-limited aggregation: contours of the mean field match contours of averaged particle density in simulation, and the modified mean field theory can form dendritic features not possible in the naive mean field theory. The morphology transition between dendritic and non-dendritic global patterns requires that BLT fronts have a Mullins-Sekerka instability of the wavefront shape, in order to form concave patterns. We compute the stability of BLT fronts numerically, and compare the results to fronts without a cutoff. A significant morphological instability of the BLT fronts exists, with a dominant wavenumber on the scale of the front width. For standard mean field fronts, no instability is found. The naive and ad hoc mean field theories are continuum-deterministic models intended to capture the behavior of a discrete stochastic system. A transformation which maps discrete systems into a continuum model with a singular multiplicative noise is known, however numerical simulations of the continuum stochastic system often give mean field behavior instead of the critical behavior of the discrete system. We have found a new interpretation of the singular noise, based on maintaining

  6. New aspects of deformed cross-strata in fluvial sandstones: Examples from Neoproterozoic formations in northern Norway

    NASA Astrophysics Data System (ADS)

    Røe, Signe-Line; Hermansen, Marita

    2006-05-01

    Extensive (20-200 m long) exposures of tabular cross-sets in Neoproterozoic fluvial sandstone in Northern Norway demonstrate that deformed cross-strata, in the form of recumbently folded cross-strata with associated massive sand, are localized features passing in both up- and down-current direction into undeformed, concave-upward or sigmoidal cross-strata. The deformation occurs in down-current inclined, tangential wedge-shaped zones beneath reactivation surfaces, and less commonly as flat-topped lenticular zones. The localized nature of the sediment deformation is attributed to local liquefaction below the top of the bed in the case of the flat-topped lenses and at the dune front in the case of the more common tangential wedges. The position of the flat-topped lenses suggests deformation by the shear stress of high-velocity, suspension-laden currents. Although liquefaction of the dune front implies the action of gravity forces, it is argued that the fluvial currents were the main driving force at the instant of bed liquefaction. Post-folding gravitational shearing probably enhanced the deformation within the upper part of the wedges, with their long, flat-lying toeset resulting from redeposition of downslope-moving liquefied sand. The down-current alternation of deformed tangential wedges and undeformed cross-strata suggests that the mechanism that triggered the liquefaction of the dune lee side was related to the fluvial system itself and hence was of autokinetic origin. The tabular cross-sets have previously been interpreted as a product of the dune upper-stage plane-bed flow regime. In this flow context, it can be speculated that the liquefaction and deformation occurred when the flow conditions approached the plane-bed phase, probably inducing a highly differential turbulent pattern and pressure fluctuations sufficient to liquefy the fine/medium sand. The small flat-topped deformation lenses also suggest liquefaction by cyclic loading, whereas the solitary

  7. Anatomy of collapsed and re-established delta front in lower Cretaceous of eastern Spitsbergen: gravitational sliding and sedimentation processes

    SciTech Connect

    Nemec, W.; Steel, R.J.; Gjelberg, J.; Collinson, J.D.; Prestholm, E.; Oxnevad, I.E.

    1988-04-01

    Spectacular coastal cliff exposures in an early Cretaceous deltaic succession near Kvalvagen in eastern Spitsbergen, Norwegian Arctic, show a variety of styles of gravity-driven deformation and resedimentation associated with delta-front progradation and instability. The large-scale collapse involved a distributary-channel sand unit, some 20 m thick, and the underlying delta slope/prodelta shaly heterolithics. The deformation was essentially brittle, whereby large blocks of the delta-front succession slid and rotated. Its gross style involved two large cuspate tear-away scars, at least 1-1.5 km wide and 50-60 m deep, separated by narrow remnant buttresses of in-situ strata. The basement in the region was tectonically active, and the delta-front failure was most likely seismically triggered. Initial infill of the collapse scars involved slumps and debris-flows, derived from scar walls and, locally, from the sliding blocks themselves. These deposits partly smoothed the local topography created by the slide blocks. This early infill was followed by deposition of thin, mainly muddy turbidites, probably shed from the scar walls by small localized failure. Renewal of fluvial supply of sand led to the main infill of the scar depressions. This stage involved effluent-generated turbidites (heterolithic), and increasingly sandier turbidites and liquefied sandflows derived from unstable, oversteepened distributary mouthbars. The mouth-bar systems eventually achieved stability and prograded across the infilled scars. They were affected by periodic storm-wave attack and sudden increases of water depth. The scar infill at that stage was subject to minor growth faulting, possibly related to new seismic tremors. 18 figures.

  8. Biphasic Investigation of Tissue Mechanical Response During Freezing Front Propagation

    PubMed Central

    Wright, Jamie; Han, Bumsoo; Chuong, Cheng-Jen

    2012-01-01

    Cryopreservation of engineered tissue (ET) has achieved limited success due to limited understanding of freezing-induced biophysical phenomena in ETs, especially fluid-matrix interaction within ETs. To further our understanding of the freezing-induced fluid-matrix interaction, we have developed a biphasic model formulation that simulates the transient heat transfer and volumetric expansion during freezing, its resulting fluid movement in the ET, elastic deformation of the solid matrix and the corresponding pressure redistribution within. Treated as a biphasic material, the ET consists of a porous solid matrix fully saturated with interstitial fluid. Temperature-dependent material properties were employed and phase change was included by incorporating the latent heat of phase change into an effective specific heat term. Model-predicted temperature distribution, the location of the moving freezing front, and the ET deformation rates through the time course compare reasonably well with experiments reported previously. Results from our theoretical model show that behind the marching freezing front, the ET undergoes expansion due to phase change of its fluid contents. It compresses the region preceding the freezing front leading to its fluid expulsion and reduced regional fluid volume fractions. The expelled fluid is forced forward and upward into the region further ahead of the compression zone causing a secondary expansion zone; which then compresses the region further downstream with much reduced intensity. Overall, it forms an alternating expansion-compression pattern which moves with the marching freezing front. The present biphasic model helps us to gain insights into some facets of the freezing process and cryopreservation treatment that could not be gleaned experimentally. Its resulting understanding will ultimately be useful to design and improve cryopreservation protocols for ETs. PMID:22757502

  9. 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.

  10. 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.

  11. 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.

  12. A numerical model of deformation and fluid-flow in an evolving thrust wedge

    NASA Astrophysics Data System (ADS)

    Strayer, Luther M.; Hudleston, Peter J.; Lorig, Loren J.

    2001-06-01

    focusing of fluid-flow in areas of active deformation. In non-dilational simulations, these zones are quite localized and are a result of the contrasting stresses in and adjacent to a brittle shear zone. In simulations with dilation, the zones of head and pressure difference are broad and regional in extent. They are ten times greater in magnitude than in non-dilation simulations, and they track a rock-damage front that moves through the wedge.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Firing up the front line.

    PubMed

    Katzenbach, J R; Santamaria, J A

    1999-01-01

    For many organizations, achieving competitive advantage means eliciting superior performance from employees on the front line--the burger flippers, hotel room cleaners, and baggage handlers whose work has an enormous effect on customers. That's no easy task. Front line workers are paid low wages, have scant hope of advancement, and--not surprisingly--often care little about the company's performance. But then how do some companies succeed in engaging the emotional energy of rank-and-file workers? A team of researchers at McKinsey & Company and the Conference Board recently explored that question and discovered that one highly effective route is demonstrated by the U.S. Marine Corps. The Marines' approach to motivation follows the "mission, values, and pride" path, which researchers say is practical and relevant for the business world. More specifically, the authors say the Marines follow five practices: they over-invest in cultivating core value; prepare every person to lead, including front line supervisors; learn when to create teams and when to create single-leader work groups; attend to all employees, not just the top half; and encourage self-discipline as a way of building pride. The authors admit there are critical differences between the Marines and most businesses. But using vivid examples from companies such as KFC and Marriott International, the authors illustrate how the Marines' approach can be translated for corporate use. Sometimes, the authors maintain, minor changes in a company's standard operating procedure can have a powerful effect on front line pride and can result in substantial payoffs in company performance. PMID:10387573

  18. 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

  19. 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

  20. 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

  1. 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

  2. Fabrication of a 3D active mixer based on deformable Fe-doped PDMS cones with magnetic actuation

    NASA Astrophysics Data System (ADS)

    Riahi, Mohammadreza; Alizadeh, Elaheh

    2012-11-01

    In this paper an active 3D mixer for lab-on-chip applications is presented. The micrometer size cone shape holes are ablated on a PMMA sheet utilizing a CO2 laser. The holes are filled with Fe micro-particles and the whole structure is molded with PDMS which cause the Fe micro-particles to be trapped in a PDMS cone structure. These Fe-doped PDMS cones are placed in a PMMA micro-channel structure fabricated by CO2 laser machining. By applying an external periodic magnetic field, the cones periodically bend in the micro-channel and stir the fluid. The fabrication method and the effect of the magnetic field on the bending of the cones with different aspect ratios is also discussed utilizing computer simulation. Doping the polymers with micro- and nano-metallic particles has been carried out by different research groups before, but according to our knowledge, application of such structures for the fabrication of a 3D active mixer has not been presented before.

  3. Slow slip and the transition from fast to slow fronts in the rupture of frictional interfaces

    PubMed Central

    Trømborg, Jørgen Kjoshagen; Sveinsson, Henrik Andersen; Scheibert, Julien; Thøgersen, Kjetil; Amundsen, David Skålid; Malthe-Sørenssen, Anders

    2014-01-01

    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

  4. 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

  5. Pulse front adaptive optics: a new method for control of ultrashort laser pulses.

    PubMed

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-07-27

    Ultrafast lasers enable a wide range of physics research and the manipulation of short pulses is a critical part of the ultrafast tool kit. Current methods of laser pulse shaping are usually considered separately in either the spatial or the temporal domain, but laser pulses are complex entities existing in four dimensions, so full freedom of manipulation requires advanced forms of spatiotemporal control. We demonstrate through a combination of adaptable diffractive and reflective optical elements - a liquid crystal spatial light modulator (SLM) and a deformable mirror (DM) - decoupled spatial control over the pulse front (temporal group delay) and phase front of an ultra-short pulse was enabled. Pulse front modulation was confirmed through autocorrelation measurements. This new adaptive optics technique, for the first time enabling in principle arbitrary shaping of the pulse front, promises to offer a further level of control for ultrafast lasers. PMID:26367595

  6. 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.

  7. 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

  8. 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.

  9. An active extensional deformation example: 19 May 2011 Simav earthquake (Mw = 5.8), Western Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Demirci, Alper; Özden, Süha; Bekler, Tolga; Kalafat, Doğan; Pınar, Ali

    2015-08-01

    The Simav Earthquake that occurred on 19 May 2011 in western Turkey was investigated on the basis of seismological data and geological observations. Approximately WNW-ESE trending surface ruptures were observed on the Simav Fault. The focal mechanism parameters of the earthquake (Mw = 5.8) and its aftershocks (Mw  >  3.5) were estimated using time-domain moment tensor inversion. A total of 2245 events were located with Geiger’s conventional absolute location method then relocated using the double difference (DD) algorithm. The calculated locations at a depths between 2 and 16 km were found to be consistent with Coulomb stress variation in the area. Average variance reduction (VR) of the solutions was calculated as ~70%. The focal parameters of strike dip and slip of the main shock, occurring at a depth of 11 km dipping towards the NNE, were estimated at 277, 62 and -92, respectively. The most striking indication of the study is that the area is dominated by normal faults with mainly WNW-ESE trends. It is also concluded that earthquakes in the region are caused by an active and regional NNE-SSW (N 12° E) trending (σ3 axis) extension regime. The mean stress ratio is 0.80, indicating a triaxial stress state. This extension is probably associated with a slab-pull force and /or roll-back due to the complex subduction process of the African Plate beneath Anatolian block along both the Hellenic and Cyprus arcs in the eastern Mediterranean region.

  10. Shock-front broadening in polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Barber, J. L.; Kadau, K.

    2008-04-01

    We analyze a model for the evolution of shock fronts in polycrystalline materials. This model is based on the idea of Meyers and Carvalho [Mater. Sci. Eng. 24, 131 (1976)] that the shock velocity anisotropy within the polycrystal is the most important factor in shock front broadening. Our analysis predicts that the shock front width increases as the 1/2 power of the front penetration distance into the crystal. Our theoretical prediction is in plausible agreement with previous experimental results for the elastic precursor rise time, and it should therefore provide a useful shock width estimate. Furthermore, our theoretical framework is also applicable to other problems involving front propagation in heterogeneous media.

  11. Dynamical and statistical properties of high-temperature self-propagating fronts: an experimental study.

    PubMed

    Rogachev, A S; Baras, F

    2009-02-01

    We present a detailed experimental study of high-temperature self-propagating fronts using image processing techniques. The intrinsic features of the wave propagation are investigated as a function of the combustion temperature TC for a model system made of titanium and silicon powders. Different front behavior is realized by changing the molar ratio x of the mixture Ti+xSi. Outside the range x=[0.3,1.5], no thermal front is propagating while inside, three regimes are observed: steady-state combustion which is characterized by a flat front propagating at constant velocity and two unsteady regimes. The combustion temperature (or the corresponding ratio x) is thus playing the role of bifurcation parameter leading from stationary state to complex behavior. In the titanium-rich mixture, the position of the front oscillates and hot spots propagate along the external border of the sample. At lower amounts of Ti, localized bright regions appear randomly and deform the front profile. The associated dynamical behavior is a relay-race mechanism which becomes more pronounced close to the combustion limit. Methods are developed to characterize the structural and dynamical properties of thermal waves near instabilities, with a special emphasis on the statistical aspects. It is clearly demonstrated that the mesoscopic scale phenomena interfere significantly with the macroscopic behavior. The experiments reveal front behaviors that cannot be described using the usual macroscopic theories. PMID:19391827

  12. 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

  13. 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

  14. Deformations in VLBI antennas

    NASA Technical Reports Server (NTRS)

    Clark, T. A.; Thomsen, P.

    1988-01-01

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

  15. Drying Mechanisms in Plasticized Latex Films: Role of Horizontal Drying Fronts.

    PubMed

    Divry, V; Gromer, A; Nassar, M; Lambour, C; Collin, D; Holl, Y

    2016-07-14

    This article presents studies on the drying kinetics of latexes with particles made progressively softer by adding increasing amounts of a plasticizer, in relation to speeds of horizontal drying fronts and particle deformation mechanisms. Global drying rates were measured by gravimetry, and speeds of the horizontal fronts were recorded using a video camera and image processing. Particle deformation mechanisms were inferred using the deformation map established by Routh and Russel (RR). This required precise measurements of the rheological properties of the polymers using a piezorheometer. The results show that latexes with softer particles dry slowly, but in our systems, this is not due to skin formation. A correlation between global drying rates and speeds of horizontal fronts could be established and interpreted in terms of the evolution of mass transfer coefficients of water in different areas of the drying system. The speeds of the horizontal drying fronts were compared with the RR model. A remarkable qualitative agreement of the curve shapes was observed; however, the fit could not be considered good. These results call for further research efforts in modeling and simulation. PMID:27244562

  16. 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

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

    NASA Astrophysics Data System (ADS)

    Blachowski, Jan; Milczarek, Wojciech; Grzempowski, Piotr

    2014-05-01

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

  18. Morphometric analysis of the thrust front of the Lucanian Apennine, southern Italy

    NASA Astrophysics Data System (ADS)

    Ivo Giano, Salvatore; Mecca, Luciana; Pascale, Stefania; Schiattarella, Marcello

    2016-04-01

    The thrust front of the southern Apennines, Italy, is formed by a north-east verging imbricate fan, transversally cut by several major rivers draining to the Ionian Sea. In the Lucanian segment of this orogen, the tectonic stack is composed by Cretaceous-Oligocene deep-sea water clayey successions and Miocene siliciclastic units, emplaced during Pliocene and Pleistocene times. It is still debated if the contractional deformation of this external part of the south-Italian orogen continues until now, because clear field evidences of recent shortening does not overcome the Middle Pleistocene. On the other hand, geomorphological features clearly indicate that the whole area suffered a significant uplift in more recent times. The present study will try to discriminate the different components of the recent and active tectonic deformation in the light of an accurate morphotectonic analysis, based on both the study of terraced surfaces and morphometric indices. The analysis of fluvial terraces arrangement and their longitudinal profiles revealed that the study area underwent a diffused rising during the Late Pleistocene. In the Holocene, the same area seems to be affected by differential uplift due to tectonic tilting toward south-east, as also supported by the increasing of the sinuosity index of the Bradano River. The tectonic mobility has been adequately proved by other indices such as the asymmetry index and the stream length-gradient index. The mapping of the SLk values has also shown that the anomalies follow NW-SE trends, suggesting a very recent activity of the ridges previously produced by contractional tectonics. Similar results have been obtained by swath profile analysis, showing peaks in coincidence of the main outcropping thrust and of more external buried structures located in the foredeep. In conclusion, all the data and geomorphic parameters led to consider the frontal portion of the Lucanian Apennines as still tectonically active, even if its recent

  19. Double-Front Detonation Waves

    NASA Astrophysics Data System (ADS)

    Gubin, S. A.; Sumskoi, S. I.; Victorov, S. B.

    According to the theory of detonation, in a detonation wave there is a sound plane, named Chapman-Jouguet (CJ) plane. There are certain stationary parameters for this plane. In this work the possibility of the second CJ plane is shown. This second CJ plane is stationary as well. The physical mechanism of non-equilibrium transition providing the existence of the second CJ plane is presented. There is a non-equilibrium state, when the heat is removed from the reaction zone and the heat capacity decreases sharply. As a result of this non-equilibrium state, the sound velocity increases, and the local supersonic zone with second sonic plane (second CJ plane) appears. So the new mode of detonation wave is predicted. Equations describing this mode of detonation are presented. The exact analytical solution for the second CJ plane parameters is obtained. The example of double-front detonation in high explosive (TNT) is presented. In this double-front structure "nanodiamond-nanographite" phase transition takes place in condensed particles of detonation products.

  20. Dipolarization Fronts from Reconnection Onset

    NASA Astrophysics Data System (ADS)

    Sitnov, M. I.; Swisdak, M. M.; Merkin, V. G.; Buzulukova, N.; Moore, T. E.

    2012-12-01

    Dipolarization fronts observed in the magnetotail are often viewed as signatures of bursty magnetic reconnection. However, until recently spontaneous reconnection was considered to be fully prohibited in the magnetotail geometry because of the linear stability of the ion tearing mode. Recent theoretical studies showed that spontaneous reconnection could be possible in the magnetotail geometries with the accumulation of magnetic flux at the tailward end of the thin current sheet, a distinctive feature of the magnetotail prior to substorm onset. That result was confirmed by open-boundary full-particle simulations of 2D current sheet equilibria, where two magnetotails were separated by an equilibrium X-line and weak external electric field was imposed to nudge the system toward the instability threshold. To investigate the roles of the equilibrium X-line, driving electric field and other parameters in the reconnection onset process we performed a set of 2D PIC runs with different initial settings. The investigated parameter space includes the critical current sheet thickness, flux tube volume per unit magnetic flux and the north-south component of the magnetic field. Such an investigation is critically important for the implementation of kinetic reconnection onset criteria into global MHD codes. The results are compared with Geotail visualization of the magnetotail during substorms, as well as Cluster and THEMIS observations of dipolarization fronts.

  1. Cluster Observations of Multiple Dipolarization Fronts

    NASA Technical Reports Server (NTRS)

    Hwang, Kyoung-Joo; Goldstein, Melvyn L.; Lee, Ensang; Pickett, Jolene S.

    2011-01-01

    We present Cluster observations of a series of dipolarization fronts (DF 1 to 6) at the central current sheet in Earth's magnetotail. The velocities of fast earthward flow following behind each DF 1-3, are comparable to the Alfven velocity, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multi-spacecraft timing analysis, DF normals are found to propagate mainly earthward at $160-335$ km/s with a thickness of 900-1500 km, which corresponds to the ion inertial length or gyroradius scale. Each DF is followed by significant fluctuations in the $x$ and $y$ components of the magnetic field whose peaks are found 1-2 minutes after the DF passage. These $(B_{x},B_{y} )$-fluctuations propagate dawnward (mainly) and earthward. Strongly enhanced field-aligned beams are observed coincidently with $(B_{x},B_{y})$ fluctuations, while an enhancement of cross-tail currents is associated with the DFs. From the observed pressure imbalance and flux-tube entropy changes between the two regions separated by the DF, we speculate that interchange instability destabilizes the DFs and causes the deformation of the mid-tail magnetic topology. This process generates significant field-aligned currents, and might power the auroral brightening in the ionosphere. However, this event is neither associated with the main substorm auroral breakup nor the poleward expansion, which might indicate that the observed multiple DFs have been dissipated before they reach the inner plasma sheet boundary.

  2. Cluster Observations of Multiple Dipolarization Fronts

    NASA Technical Reports Server (NTRS)

    Hwang, K.-J.; Goldstein, M. L.; Lee, E.; Pickett, J. S.

    2011-01-01

    We present Cluster observations of a series of dipolarization fronts (DF 1 to 6) at the central current sheet in Earth's magnetotail. The velocities of fast earthward flow following behind each DF 1.3 are comparable to the Alfven velocity, indicating that the flow bursts might have been generated by bursty reconnection that occurred tailward of the spacecraft. Based on multispacecraft timing analysis, DF normals are found to propagate mainly earthward at 160.335 km/s with a thickness of 900-1500 km, which corresponds to the ion inertial length or gyroradius scale. Each DF is followed by significant fluctuations in the x and y components of the magnetic field whose peaks are found 1.2 min after the DF passage. These (B(sub x), B(sub y)) fluctuations propagate dawnward (mainly) and earthward. Strongly enhanced field-aligned beams are observed coincidently with (B(sub x), B(sub y)) fluctuations, while an enhancement of cross-tail currents is associated with the DFs. From the observed pressure imbalance and flux tube entropy changes between the two regions separated by the DF, we speculate that interchange instability destabilizes the DFs and causes the deformation of the midtail magnetic topology. This process generates significant field-aligned currents and might power the auroral brightening in the ionosphere. However, this event is associated with neither the main substorm auroral breakup nor the poleward expansion, which might indicate that the observed multiple DFs have been dissipated before they reach the inner plasma sheet boundary.

  3. 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.

  4. The filamentary structure of mixing fronts and its control on reaction kinetics in porous media flows

    NASA Astrophysics Data System (ADS)

    de Anna, Pietro; Dentz, Marco; Tartakovsky, Alexandre; Le Borgne, Tanguy

    2014-07-01

    The mixing dynamics resulting from the combined action of diffusion, dispersion, and advective stretching of a reaction front in heterogeneous flows leads to reaction kinetics that can differ by orders of magnitude from those measured in well-mixed batch reactors. The reactive fluid invading a porous medium develops a filamentary or lamellar front structure. Fluid deformation leads to an increase of the front length by stretching and consequently a decrease of its width by compression. This advective front deformation, which sharpens concentration gradients across the interface, is in competition with diffusion, which tends to increase the interface width and thus smooth concentration gradients. The lamella scale dynamics eventually develop into a collective behavior through diffusive coalescence, which leads to a disperse interface whose width is controlled by advective dispersion. We derive a new approach that quantifies the impact of these filament scale processes on the global mixing and reaction kinetics. The proposed reactive filament model, based on the elementary processes of stretching, coalescence, and fluid particle dispersion, provides a new framework for predicting reaction front kinetics in heterogeneous flows.

  5. 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

  6. Deformable Nanolaminate Optics

    SciTech Connect

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

    2006-05-12

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

  7. 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

  8. 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.

  9. 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

  10. HINS Linac front end focusing system R&D

    SciTech Connect

    Apollinari, G.; Carcagno, R.H.; Dimarco, J.; Huang, Y.; Kashikhin, V.V.; Orris, D.F.; Page, T.M.; Rabehl, R.; Sylvester, C.; Tartaglia, M.A.; Terechkine, I.; /Fermilab /Argonne

    2008-08-01

    This report summarizes current status of an R&D program to develop a focusing system for the front end of a superconducting RF linac. Superconducting solenoids will be used as focusing lenses in the low energy accelerating sections of the front end. The development of focusing lenses for the first accelerating section is in the production stage, and lens certification activities are in preparation at FNAL. The report contains information about the focusing lens design and performance, including solenoid, dipole corrector, and power leads, and about cryogenic system design and performance. It also describes the lens magnetic axis position measurement technique and discusses scope of an acceptance/certification process.

  11. 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.

  12. Super-heated flooding fronts on tidal flats

    NASA Astrophysics Data System (ADS)

    Rinehimer, J. P.; Thomson, J. M.; Chickadel, C.

    2012-12-01

    The flooding tide over a tidal flat is a thin fluid flow with complex dynamics and relation to benthic activity. Temperature observations (Figure 1) on the Skagit Bay, WA, USA tidal flats during the summer suggest that the leading edge of the flooding front is up to 5 °C warmer than the exposed sediment and 15 °C warmer than the bulk tide water. Using a numerical model, we evaluate the thermodynamic budget of this thin layer in a Lagrangian frame following the flood tide. Both local and flux heating terms are significant. The local heating is modulated by the turbidity of the flooding front, which controls the uptake of solar radiation, and by the exchange of heat between the flooding front and the sediment. The flux mechanisms include horizontal diffusion and advection due to net circulation within the frontal control volume. Due to the no-slip condition at the bed, circulation of warmer water near the surface moves toward the front while cooler water leaves the volume near the bed.Airborne infrared imagery taken during the flood tide at Skagit Bay, WA, USA on 23 June 2009 starting at 3:00 PM PDT. Cooler surface temperatures are darker The exposed tidal flats are warmer than the Skagit Bay water due to solar heating while exposed. The leading edge of the flood front is indicated and is up to 5 °C warmer than the exposed sediment. The airborne imagery was taken over 50 minutes and mosaicked together.

  13. 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

  14. 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.

  15. Learning Deformable Shape Manifolds

    PubMed Central

    Rivera, Samuel; Martinez, Aleix

    2011-01-01

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

  16. 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.

  17. 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.

  18. 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.

  19. Front pinning in single vortex flows

    NASA Astrophysics Data System (ADS)

    Mahoney, John; Mitchell, Kevin

    2014-11-01

    We study fronts propagating in 2D fluid flows and show that there exist stable invariant front configurations for fairly generic flows. Here we examine the simple flow which combines a single vortex with an overall ``wind.'' We discuss how the invariant front can be derived from a simple 3D ODE. Existence of this front can then be understood in terms of bifurcations of fixed points, and the behavior of the invariant ``sliding front'' submanifold. Interestingly, the front bifurcation precedes the saddle-node bifurcation which gives rise to the vortex. This elementary structure has application in chemical reactor beds and laminar combustion in well-mixed fluids. We request that this talk follow the related talks by our collaborators Tom Solomon, Savannah Gowen, and Sarah Holler.

  20. Reaction front formation in contaminant plumes.

    PubMed

    Cribbin, Laura B; Winstanley, Henry F; Mitchell, Sarah L; Fowler, Andrew C; Sander, Graham C

    2014-12-15

    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. PMID:25461883

  1. 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.

  2. Summit Explosive Activity and Deformation: Constraints On The Etna SE Crater Through Tilt Variations During The 1998-2000 Lava Fountains

    NASA Astrophysics Data System (ADS)

    Bonaccorso, A.

    We investigate the relationships between the strain expected from the explosive action of a volcanic conduit, the paroxystic lava fountain events occurring recently at Etna, and the high precision continuous tilt signals recorded during such events with refer- ence to the ones occurring at the SE crater. Using both the inclusion and dislocation theories, it has been shown that the displacements expected from the explosive action of the volcanic conduits are defined by an equation which includes a term proportional to a line dilatation integral plus an integral that subtracts the effects proportional to a line of vertical double forces. Then, from these equations, it is possible to obtain the expected tilt. We conducted a comparison and an analysis with the tilt signals recorded at the Pizzi Deneri (PDN) volcanological observatory located in the high north-eastern flank of Mt. Etna. Here, an 80 m long-base mercury tiltmeter is installed along two partially underground tunnels. The instrument, utilising optical laser sensors for mea- suring the level changes at the extremities, is very stable with a real precision of 0.01 microradians. At the PDN distance from crater, as expected from the conduit theory, deformation effects can be very small and difficult to detect even if provoked by strong explosions. Nevertheless, in particular situations during the paroxystic activity of the June 24, 2000 (violent explosive phase with only 30 minutes duration, instrumental sampling of 1 data/minute) we recorded small (0.1-0.2 microradians) but very clear and significant tilt variations on the radial component. On the basis of the theoreti- cal equations, these variation allow us to fix constraints on the SE conduit geometry (diameter) and the characteristics of the surrounding medium (rigidity coefficient).

  3. 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.

  4. Juan de Fuca Plate Ridge-to-Trench Experiment: initial results from active source seismic imaging of the Juan de Fuca plate and Cascadia fore-arc (Invited)

    NASA Astrophysics Data System (ADS)

    Carbotte, S. M.; Canales, J.; Carton, H. D.; Han, S.; Gibson, J. C.; Janiszewski, H. A.; Horning, G.; Nedimovic, M. R.; Abers, G. A.; Trehu, A. M.

    2013-12-01

    Active source seismic data were acquired during the Juan de Fuca Ridge-to-Trench experiment (June-July 2012) to characterize the evolution and structure of the Juan de Fuca plate from formation at the ridge, through evolution in the plate interior, to subduction at the Cascadia trench. The survey provides plate-scale images of the sediments, crust, and shallowest mantle along two ridge-perpendicular transects, one extending from Axial seamount to the Oregon margin near Hydrate Ridge and the other from near Endeavour segment to Grays Harbor offshore Washington. In addition, a 450 km long trench-parallel line ~10 km seaward of the Cascadia deformation front was acquired to characterize variations in plate structure along the margin. Coincident long-streamer (8 km) multi-channel seismic (MCS) and wide-angle ocean bottom seismometer (OBS) data were collected along each transect. Using these data, our current investigations focus on the properties of the thick sediment blanket covering the Juan de Fuca plate and evidence for fluid flow at the deformation front, crustal structure within the plate interior and near the deformation front, and tracking the downgoing plate beneath the margin. Highlights include the discovery of numerous pockmarks on the seafloor providing evidence of active fluid flow up to 60 km west of the deformation front. Along the Oregon transect, a bright decollement horizon is imaged at ~1sec twtt above basement whereas at the Washington margin, protothrusts of the deformation front reach to the top of the oceanic crust. Variations in sediment properties are documented within the margin-parallel transect with changes in the stratigraphic level of decollement. While crustal thickness is quite uniform along the margin (~ 6 km), variations in crustal reflectivity and in shallowest mantle velocities are observed over ~30-50 km length scales that could be related to structural variations in the Cascadia subduction zone. Further landward, the top of the

  5. Colorado Front Range Surface Ozone Analysis

    NASA Astrophysics Data System (ADS)

    McClure-Begley, A.; Petropavlovskikh, I. V.; Oltmans, S. J.; Kofler, J.; Petron, G.; Cothrel, H.

    2014-12-01

    The Colorado Front Range is a unique geographical region for air quality studies, including research of surface level ozone. Not only does surface ozone play a critical role in regulating the oxidation capacity of the atmosphere, but is a primary contributor to local smog and leads to public health complications and altered ecosystem functioning. The high frequency of sunny days, increasing population and pollution, and Mountain/Valley air dynamics of this region provide atmospheric conditions suitable for production and accumulation of ozone at the surface. This region of Colorado is currently in an ozone non-attainment status due to an assortment of contributing factors. Precursor emissions from pollution, wild-fires, and gas and oil production; along with stratosphere-troposphere exchange, can all result in high ozone episodes over the Colorado Front Range. To understand the dynamics of ozone accumulation in this region, Thermo-Scientific ozone monitors have been continuously sampling ozone from 4 different altitudes since the early 2000s. Analysis of ozone data in relation to Nitrogen Oxides (NOx), Methane (CH4), Carbon Monoxide (CO), wind-conditions and back-trajectory air mass origins help to address local ozone precursor emissions and resulting high ozone episodes. Increased ozone episodes are scrutinized with regards to dominant wind direction to determine main precursor emission sources. Analysis of this data reveals a strong influence of precursor emissions from the North-East wind sector, with roughly 50% of ozone exceedances originating from winds prevailing from this direction. Further, correlation with methane is enhanced when prevailing winds are from the North-East; indicative of influence from natural gas processes and feedlot activity. Similar analysis is completed for the North-West wind sector exceedances, with strong correlation to carbon monoxide; likely related to emissions from biomass burning events and forest fires. In depth analysis of

  6. Segmentation and kinematics of the Kazerun fault system (southern Iran): Implications for active deformation partitioning within the Zagros fold-and-thrust belt

    NASA Astrophysics Data System (ADS)

    Authemayou, C. A.; Bellier, O. B.; Chardon, D. C.; Malekzade, Z. M.; Abbassi, M. A.

    2003-04-01

    right-lateral fault located south of-, and running parallel to the Main Reverse Fault that accommodates the orogen-parallel, strike-slip component of oblique plate convergence (max 10-17 mm/yr) at the rear of the Zagros fold-and-thrust belt. Slip transfer from the Main Recent fault to the KFS leads to the southeastward extrusion of a crustal wedge pinched off between the Main Reverse Fault and the KFS. Our preliminary results therefore suggest that the KFS plays a key role in partitioning active deformation in the fold-and-thrust belt by distributing active orogen-parallel, right-lateral slip from along the Main Recent fault throughout the Zagros fold and thrust belt.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. Fluctuations as stochastic deformation.

    PubMed

    Kazinski, P O

    2008-04-01

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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. Stability of cosmological detonation fronts

    NASA Astrophysics Data System (ADS)

    Mégevand, Ariel; Membiela, Federico Agustín

    2014-05-01

    The steady-state propagation of a phase-transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very close to the Jouguet point, where our approach breaks down.

  19. Stability of cosmological deflagration fronts

    NASA Astrophysics Data System (ADS)

    Mégevand, Ariel; Membiela, Federico Agustín

    2014-05-01

    In a cosmological first-order phase transition, bubbles of the stable phase nucleate and expand in the supercooled metastable phase. In many cases, the growth of bubbles reaches a stationary state, with bubble walls propagating as detonations or deflagrations. However, these hydrodynamical solutions may be unstable under corrugation of the interface. Such instability may drastically alter some of the cosmological consequences of the phase transition. Here, we study the hydrodynamical stability of deflagration fronts. We improve upon previous studies by making a more careful and detailed analysis. In particular, we take into account the fact that the equation of motion for the phase interface depends separately on the temperature and fluid velocity on each side of the wall. Fluid variables on each side of the wall are similar for weakly first-order phase transitions, but differ significantly for stronger phase transitions. As a consequence, we find that, for large enough supercooling, any subsonic wall velocity becomes unstable. Moreover, as the velocity approaches the speed of sound, perturbations become unstable on all wavelengths. For smaller supercooling and small wall velocities, our results agree with those of previous works. Essentially, perturbations on large wavelengths are unstable, unless the wall velocity is higher than a critical value. We also find a previously unobserved range of marginally unstable wavelengths. We analyze the dynamical relevance of the instabilities, and we estimate the characteristic time and length scales associated with their growth. We discuss the implications for the electroweak phase transition and its cosmological consequences.

  20. Geometrical shock dynamics, formation of singularities and topological bifurcations of converging shock fronts

    NASA Astrophysics Data System (ADS)

    Suramlishvili, Nugzar; Eggers, Jens; Fontelos, Marco

    2014-11-01

    We are concerned with singularities of the shock fronts of converging perturbed shock waves. Our considerations are based on Whitham's theory of geometrical shock dynamics. The recently developed method of local analysis is applied in order to determine generic singularities. In this case the solutions of partial differential equations describing the geometry of the shock fronts are presented as families of smooth maps with state variables and the set of control parameters dependent on Mach number, time and initial conditions. The space of control parameters of the singularities is analysed, the unfoldings describing the deformations of the canonical germs of shock front singularities are found and corresponding bifurcation diagrams are constructed. Research is supported by the Leverhulme Trust, Grant Number RPG-2012-568.

  1. Shock front broadening in polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Barber, John; Kadau, Kai

    2008-03-01

    We analyze a model for the evolution of weak shock fronts (or elastic precursor waves) in polycrystalline materials. This model is based on the idea of Meyers and Carvalho [Mater. Sci. Eng. 24, 131 (1976)] that the shock velocity anisotropy within the polycrystal is the most important factor in shock front broadening. Our analysis predicts that the shock front width increases as the 1/2 power of the front penetration distance into the crystal. Our theoretical prediction is in plausible agreement with previous experimental results for the elastic precursor rise time, and it should therefore provide a useful shock width estimate. Furthermore, our theoretical framework is also applicable to other problems involving front propagation in heterogeneous media.

  2. 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.

  3. 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.

  4. 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.

  5. 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).

  6. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

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

  7. High-aspect-ratio line focus for an x-ray laser by a deformable mirror

    SciTech Connect

    Yoon, G.; Jitsuno, T.; Kato, Y.; Nakatsuka, M.

    1997-02-01

    A high-aspect-ratio line focus is required on a plane target in x-ray laser experiments for obtaining a high gain-length product. Inherent wave-front aberrations in line-focusing optics, which consist of a cylindrical lens and a spherical lens, are discussed with respect to beam diameter. The nonuniformity of the linewidth that is due to the aberrations is also calculated by the ABCD matrix method. A deformable mirror of a continuous plate type with a diameter of 185 mm provides an adequate wave-front distribution for compensating for the wave-front aberration. The wave-front control by the deformable mirror realizes a fine linewidth of 25 {mu}m and 18.2 mm long, corresponding to the aspect ratio of 728. The linewidth is three times the diffraction limit. The intensity distribution along the line focus is also improved. {copyright} 1997 Optical Society of America

  8. High-aspect-ratio line focus for an x-ray laser by a deformable mirror.

    PubMed

    Yoon, G Y; Jitsuno, T; Kato, Y; Nakatsuka, M

    1997-02-01

    A high-aspect-ratio line focus is required on a plane target in x-ray laser experiments for obtaining a high gain-length product. Inherent wave-front aberrations in line-focusing optics, which consist of a cylindrical lens and a spherical lens, are discussed with respect to beam diameter. The nonuniformity of the linewidth that is due to the aberrations is also calculated by the ABCD matrix method. A deformable mirror of a continuous plate type with a diameter of 185 mm provides an adequate wave-front distribution for compensating for the wave-front aberration. The wave-front control by the deformable mirror realizes a fine linewidth of 25 microm and 18.2 mm long, corresponding to the aspect ratio of 728. The linewidth is three times the diffraction limit. The intensity distribution along the line focus is also improved. PMID:18250748

  9. 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.

  10. Front Range of the Rockies

    NASA Technical Reports Server (NTRS)

    2001-01-01

    These MISR images from May 12, 2001 (Terra orbit 7447) include portions of southern Wyoming, central Colorado, and western Nebraska. The top view is from the instrument's vertical-viewing (nadir) camera. The bottom image is a stereo 'anaglyph' generated using data from the nadir and 46-degree-forward cameras. Viewing the anaglyph with red/blue glasses (red filter over your left eye) gives a 3-D effect. To facilitate stereo viewing, the images have been oriented with north at the left. Each image measures 422 kilometers x 213 kilometers.

    The South Platte River enters just to the right of center at the top of the images. It wends its way westward (down), then turns southward (right) where it flows through the city of Denver. Located at the western edge of the Great Plains, Denver is nicknamed the 'Mile High City', a consequence of its 1609-meter (5280-foot) elevation above sea level. It shows up in the imagery as a grayish patch surrounded by numerous agricultural fields to the north and east. Denver is situated just east of the Front Range of the Rocky Mountains, located in the lower right of the images. The Rockies owe their present forms to tectonic uplift and sculpting by millions of years of erosion. Scattered cumulus clouds floating above the mountain peaks are visible in these images, and stand out most dramatically in the 3-D stereo view.

    To the north of Denver, other urban areas included within these images are Boulder, Greeley, Longmont, and Fort Collins, Colorado; Cheyenne and Laramie, Wyoming; and Scottsbluff, Nebraska.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  11. 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. PMID:8186726

  12. Spatial and temporal variability of deformation in the Northern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Gunderson, Kellen L.

    Knowing the spatial and temporal variabilty of deformation in mountain belts is essential for understanding discrepancies between geodetic and geologic measurements of deformation and for accurately assessing seismic hazards. High-resolution deformational histories for three transects of the Northern Apennine mountain front, Italy, obtained from dated synorogenic growth strata, elucidate the spatial and temporal variabilty of thrust fault deformation in the Apennines since 3.0 Ma. Inverse and forward modeling of growth strata exposed in the Stirone River section shows the Salsomaggiore thrust exhibits a high frequency slip rate variability at 40-500 kyr timescales that is likely related to strain partitioning on connected imbricate thrusts. A high-resolution age model for the Pleistocene Enza growth strata section, which contains sedimentary facies spanning both marine and terrestrial environments, shows that the growth strata exposed at the Apennine mountain front not only record unsteady deformation but also record variable surface processes that can obscure true deformational behavior. A comparison of mountain front deformation at all three transects shows that unsteady deformation was asynchronous along orogenic strike between 1.0-3.0 Ma. A shift to synchronized deformation at all three transects is observed after 1.0 Ma. This shift also corresponds to a kinematic reorganization of the Apennine wedge and the initiation of thick-skinned thrusting. This kinematic reorganization was driven by climatically-driven overfilling of the Po foreland beginning at ~1.4 Ma, which had the effect of lowering the Apennine orogenic wedge taper and causing the wedge to respond by initiating out-of-sequence, basement involved reverse faulting localized at the present day Apennine mountain front.

  13. 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.

  14. Meandering and unstable reentrant wave fronts induced by acetylcholine in isolated canine right atrium.

    PubMed

    Ikeda, T; Wu, T J; Uchida, T; Hough, D; Fishbein, M C; Mandel, W J; Chen, P S; Karagueuzian, H S

    1997-07-01

    The mechanism(s) by which acetylcholine (ACh) increases atrial vulnerability to reentry and maintains its activity for longer durations remains poorly defined. In the present study we used high-resolution activation maps to test the hypothesis that ACh promotes meandering of atrial reentrant wave fronts, resulting in breakup and the generation of new wave fronts that sustain the activity. Reentry was induced in 11 isolated canine right atrial tissues (3.8 x 3.2 cm) by a premature point stimulus (S2) before and after superfusion with ACh (15 x 10(-6) M). Endocardial isochronal activation maps were constructed with the use of 509 bipolar electrodes (1.6-mm spatial resolution), and the dynamics of the activation wave fronts were visualized with animation. A vulnerable period was found during which an S2 current strength > 4.4 +/- 2.5 mA [lower limit of vulnerability (LLV)] and < 26 +/- 13 mA [upper limit of vulnerability (ULV)] induced a single stationary reentrant wave front that lasted 3 +/- 2.5 s with a period of 159 +/- 17 ms (16 episodes). AC shortened the refractory period from 100 +/- 12 to 59 +/- 9 ms (P < 0.001) and increased vulnerability to reentry induction by simultaneous decrease in the LLV (0.7 +/- 0.2 mA, P < 0.001) and an increase in the ULV (82 +/- 24 mA, P < 0.01). ACh accelerated the rate (period of 110 +/- 16 ms, P < 0.001) and converted the stationary reentrant wave front to a nonstationary (meandering) reentrant wave front showing polymorphic electrograms, i.e., "fibrillation-like" activity (22 episodes). Rapid meandering of the reentry tip led to wave front breakup (18 episodes) and the generation of new wave fronts (19 episodes). These wave front dynamics also led to sustained (76 +/- 224 s, P < 0.001) fibrillation-like electrograms. We conclude that ACh increases the ULV and promotes meandering of a single reentrant wave front, leading to breakup and the generation of new wave fronts. Single meandering and complex wave front dynamics cause

  15. 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.

  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. Transpressional tectonics and nappe stacking along the Southern Variscan Front of Morocco

    NASA Astrophysics Data System (ADS)

    Cerrina Feroni, Andrea; Ellero, Alessandro; Malusà, Marco G.; Musumeci, Giovanni; Ottria, Giuseppe; Polino, Riccardo; Leoni, Leonardo

    2010-07-01

    The Southern Variscan Front in the Tinerhir area involves Palaeozoic allochthonous units (Ouaklim and Tilouine units) thrust onto the northern edge of the West African Craton during late Carboniferous time. Illite crystallinity data highlight an anchizonal grade for the Ouaklim Unit, and a diagenesis-anchizone transition for the Tilouine Unit during deformation phase D1. The tectonic stack is crosscut by major dextral reverse faults bounding E-W trending domains of dominant shortening deformation (central domain) and strike-slip deformation (northern and southern domains), later segmented by a network of post-Variscan faults. This complex deformation pattern is the result of kinematic partitioning of dextral transpression along the Southern Variscan Front, coeval with the Neovariscan (300-290 Ma) oblique convergence observed at the scale of the whole Moroccan Variscides. Partitioning of dextral transpression described in the Tinerhir area is consistent with dextral wrench faulting along the Tizi n’ Test Fault, and with Appalachian-style south-directed thrusting in the Tinerhir and Bechar-Bou Arfa areas.

  18. 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

  19. Time and space evolution of an active creeping zone: competition between brittle and ductile deformations, new insights from microstructure studies of SAFOD (San Andreas Fault Observatory at Depth) samples

    NASA Astrophysics Data System (ADS)

    Richard, J.; Gratier, J.; Doan, M.; Renard, F.; Boullier, A.

    2012-12-01

    Creep processes can relax an important part of the tectonic stresses in active faults, either by permanent steady-state creep or by episodic post-seismic creep. Here, our goal is to better constrain the micro-physical parameters that control this transition between seismic and aseismic behavior, both in time and in space. We present new results from microstructural studies on natural samples collected from the SAFOD (San Andreas Fault Observatory at Depth) drilling project, located on the Parkfield segment of the San Andreas Fault (SAF). Seven samples were collected from the main active creeping zone: the Central Deforming Zone at 3301-3303m depth. We performed chemical and mineralogical analyses and microscope observations on twenty thin sections cut from those samples. In a previous study (Gratier et al., Geology, 2011), we have already shown that pressure solution creep is an active deformation process in the SAF. We propose a model of microstructural evolution to characterize in which conditions pressure solution creep is efficient enough to relax stress and to prevent the nucleation of moderate to large earthquakes. We show that two crucial parameters may accelerate pressure solution: the presence of phyllosilicates and the degree of rock fracturing. The initial structure and composition of the rocks may explain why pressure solution creep is efficient or not. Moreover, both the content of phyllosilicates and the degree of fracture may evolve with time at various scales during the seismic cycle: - During interseismic periods (years to millennia): fracturing activates postseismic creep. However, the progressive healing of the fracture annihilates this effect. Meanwhile, growth of phyllosilicate minerals, associated with postseismic fluid flow may also activate the creep rate. - During much longer geological periods (hundred thousands to millions of years), the composition of gouge material deformed by pressure solution evolves by the passive concentration of

  20. 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 ...

  1. 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.

  2. 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.

  3. 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.

  4. Coarsening to chaos-stabilized fronts

    NASA Astrophysics Data System (ADS)

    Poon, Ka-Fai; Wittenberg, Ralf W.

    2011-01-01

    We investigate a model for pattern formation in the presence of Galilean symmetry proposed by Matthews and Cox [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.62.R1473 62, R1473 (2000)], which has the form of coupled generalized Burgers- and Ginzburg-Landau-type equations. With only the system size L as a parameter, we find distinct “small-L” and “large-L” regimes exhibiting clear differences in their dynamics and scaling behavior. The long-time statistically stationary state contains a single L-dependent front, stabilized globally by spatiotemporally chaotic dynamics confined away from the front. For sufficiently large domains, the transient dynamics include a state consisting of several viscous shocklike structures that coarsens gradually, before collapsing to a single front when one front absorbs the others.

  5. 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.

  6. 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.

  7. Deformations of 3-algebras

    SciTech Connect

    Figueroa-O'Farrill, Jose Miguel

    2009-11-15

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

  8. RF Front End Interface and AGC Modification

    NASA Technical Reports Server (NTRS)

    Yost, S. R.

    1982-01-01

    The latest RF front end built by Burhans (Mini-L-82) was successfully interfaced to the Ohio University LORAN-C receiver. In order for the front end to operate optimally, modifications were made to existing automatic gain control (AGC) circuitry already developed for the Ohio University LORAN-C receiver. The hardware modifications to the AGC and other interface circuitry, as well as some preliminary results are discussed.

  9. 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

  10. 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.

  11. 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.

  12. Electron acceleration in a wavy shock front

    NASA Astrophysics Data System (ADS)

    Vandas, M.; Karlický, M.

    2011-07-01

    Context. It is known that electrons are accelerated at nearly perpendicular shocks by the drift mechanism. And it is also known that energy gain of electrons caused by this mechanism is not very high. Therefore it was suggested in the past that the energy gain might be increased if shocks had wavy fronts. For instance, there were attempts to explain coronal type II burst and their fine structure by electron acceleration in a wavy shock front. Aims: We studied electron acceleration numerically at nearly perpendicular wavy shocks for coronal conditions and compared it with analytical results on electron acceleration at nearly perpendicular plane shocks. Methods: An analytical model of a wavy shock front was used and trajectories of electrons in it and around it were calculated numerically in a guiding centre approximation. Results: We found that energy gains of electrons at a wavy shock front and a corresponding smoothed-into-plane shock on the average were comparable. That is why they do not depend significantly on the shock thickness, magnetic field profile inside the shock, and shock wavy form. They do depend on the angle between the smoothed shock front and ambient magnetic field. Conclusions: On average, a wavy shock front does not significantly increase an acceleration efficiency. Energy gain remarkably exceeds an average level for some combinations of initial parameters. Distribution functions of accelerated electrons have a patchy structure, which is prone to inducing plasma instabilities that will generate plasma waves. This may have relevance to the problem of type II burst origin.

  13. IFA - INTELLIGENT FRONT ANNOTATION PROGRAM

    NASA Technical Reports Server (NTRS)

    Burke, G. R.

    1994-01-01

    An important aspect of an ASIC (Application Specific Integrated Circuit) design process is verification. The design must not only be functionally accurate, but it must also maintain the correct timing. After a circuit has been laid out, one can utilize the Back Annotation (BA) method to simulate the design and obtain an accurate estimate of performance. However, this can lead to major design changes. It is therefore preferable to eliminate potential problems early in this process. IFA, the Intelligent Front Annotation program, assists in verifying the timing of the ASIC early in the design process. Many difficulties can arise during ASIC design. In a synchronous design, both long path and short path problems can be present. In modern ASIC technologies, the delay through a gate is very dependent on loading. This loading has two main components, the capacitance of the gates being driven and the capacitance of the metal tracks (wires). When using GaAs gate arrays, the metal line capacitance is often the dominating factor. Additionally, the RC delay through the wire itself is significant in sub-micron technologies. Since the wire lengths are unknown before place and route of the entire chip, this would seem to postpone any realistic timing verification until towards the end of the design process, obviously an undesirable situation. The IFA program estimates the delays in an ASIC before layout. Currently the program is designed for Vitesse GaAs gate arrays and, for input, requires the expansion file which is output by the program GED; however, the algorithm is appropriate for many different ASIC types and CAE platforms. IFA is especially useful for devices whose delay is extremely dependent on the interconnection wiring. It estimates the length of the interconnects using information supplied by the user and information in the netlist. The resulting wire lengths are also used to constrain the Place and Route program, ensuring reasonable results. IFA takes locality into

  14. 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. PMID:8274868

  15. 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.

  16. 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.

  17. 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.

  18. DESIGN OF MEDICAL RADIOMETER FRONT-END FOR IMPROVED PERFORMANCE

    PubMed Central

    Klemetsen, Ø.; Birkelund, Y.; Jacobsen, S. K.; Maccarini, P. F.; Stauffer, P. R.

    2011-01-01

    We have investigated the possibility of building a singleband Dicke radiometer that is inexpensive, small-sized, stable, highly sensitive, and which consists of readily available microwave components. The selected frequency band is at 3.25–3.75 GHz which provides a reasonable compromise between spatial resolution (antenna size) and sensing depth for radiometry applications in lossy tissue. Foreseen applications of the instrument are non-invasive temperature monitoring for breast cancer detection and temperature monitoring during heating. We have found off-the-shelf microwave components that are sufficiently small (< 5 mm × 5 mm) and which offer satisfactory overall sensitivity. Two different Dicke radiometers have been realized: one is a conventional design with the Dicke switch at the front-end to select either the antenna or noise reference channels for amplification. The second design places a matched pair of low noise amplifiers in front of the Dicke switch to reduce system noise figure. Numerical simulations were performed to test the design concepts before building prototype PCB front-end layouts of the radiometer. Both designs provide an overall power gain of approximately 50 dB over a 500 MHz bandwidth centered at 3.5 GHz. No stability problems were observed despite using triple-cascaded amplifier configurations to boost the thermal signals. The prototypes were tested for sensitivity after calibration in two different water baths. Experiments showed superior sensitivity (36% higher) when implementing the low noise amplifier before the Dicke switch (close to the antenna) compared to the other design with the Dicke switch in front. Radiometer performance was also tested in a multilayered phantom during alternating heating and radiometric reading. Empirical tests showed that for the configuration with Dicke switch first, the switch had to be locked in the reference position during application of microwave heating to avoid damage to the active components

  19. 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

  20. 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.

  1. 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.

  2. 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

  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. Risk factors for vertebral deformities in men: relationship to number of vertebral deformities. European Vertebral Osteoporosis Study Group.

    PubMed

    Ismail, A A; O'Neill, T W; Cooper, C; Silman, A J

    2000-02-01

    Recent epidemiological studies suggest a similar overall prevalence of vertebral deformity in men to that in women, though the influence of increasing age on the prevalence of vertebral deformity is less marked in men. However, most affected men have only a single or two vertebral deformities, which may be unrelated to osteoporosis. The aim of this study was to examine the role of risk factors, previously demonstrated to be associated with vertebral osteoporosis in females, in men with single/dual deformities compared to those with multiple deformities. Age stratified random samples of men aged 50 years and over were recruited from population registers in 30 European centers as part of the European Vertebral Osteoporosis Study (EVOS). Subjects had a lateral spinal radiograph and the presence of vertebral deformity was determined using the McCloskey algorithm. Lifestyle and other risk factor data were obtained from an interviewer-administered questionnaire. In all 6937 men with a mean age of 64.4 (SD = 8.5) years were studied of whom 738 (10.6%) subjects had one or two deformities, and 109 (1.6%) subjects had three or more deformities. There was a marked increase in the prevalence of multiple vertebral deformities with increasing age, but only a modest effect of age on the prevalence of single deformities. Associations between various risk factors for osteoporosis and vertebral deformity were analyzed separately in men with single/dual vertebral deformity from those with three or more deformities using logistic regression. After adjustment for age, there were statistically significant associations between the following risk factors and multiple deformities: previous hip fracture (odds ratio [OR] 10.5), lack of regular physical activity (OR 2.9), low body mass (OR 2.5), and previous steroid use (OR 2.3). By contrast, there were only weak associations with these same variables in males with single/dual deformities and, apart from poor self-reported general health, all

  6. Pore invasion dynamics during fluid front displacement - an interfacial front model

    NASA Astrophysics Data System (ADS)

    Moebius, F.; Or, D.

    2013-12-01

    The dynamics of fluid fronts in porous media shape subsequent phase distribution and the transport properties of the partially saturated region with implications ranging from gaseous transport to plant roots to extraction or injection of fluids to petroleum reservoirs. What macroscopically seems as a smooth and continuous motion of a displacement fluid front, involves numerous rapid pore-scale interfacial jumps often resembling avalanches of invasion events. We present a 2D model for simulating interfacial front displacement that was developed to study details of invasion dynamics at the front and to systematically study effects of boundary conditions on the resulting macroscopic properties after passage of a front. The interfacial front is represented by hydraulically connected sinusoidal capillaries allowing for redistribution and capillary pressure relaxation through exchange with neighboring interfaces. The model focuses on processes at the front and neglects interfacial redistribution left behind the front as well as saturated fluid flow below the front. The description of the dynamics of the rapid non-wetting fluid invasions induced by constant wetting fluid withdrawal includes capillary, viscous and hydrostatic component and inertia. Results show that the additional inertial force (not considered in previous studies) does significantly affect invasion pathways such as the hypothesized 'consecutive jumps'. The menisci jump velocities show a strong relation to geometrical throat dimensions that reflect local capillary gradients. The front model further enables to link boundary conditions (macroscopic Capillary number, throat size distribution) effects on pore invasion sequences and impact on residual wetting phase entrapment and front morphology. A limited comparison of model predictions with experimental results from sintered glass-beads micro-models will be presented.

  7. 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.

  8. 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.

  9. Shocks and cold fronts in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Markevitch, Maxim; Vikhlinin, Alexey

    2007-05-01

    The currently operating X-ray imaging observatories provide us with an exquisitely detailed view of the Megaparsec-scale plasma atmospheres in nearby galaxy clusters. At z<0.05, the Chandra's 1 angular resolution corresponds to linear resolution of less than a kiloparsec, which is smaller than some interesting linear scales in the intracluster plasma. This enables us to study the previously unseen hydrodynamic phenomena in clusters: classic bow shocks driven by the infalling subclusters, and the unanticipated “cold fronts,” or sharp contact discontinuities between regions of gas with different entropies. The ubiquitous cold fronts are found in mergers as well as around the central density peaks in “relaxed” clusters. They are caused by motion of cool, dense gas clouds in the ambient higher-entropy gas. These clouds are either remnants of the infalling subclusters, or the displaced gas from the cluster's own cool cores. Both shock fronts and cold fronts provide novel tools to study the intracluster plasma on microscopic and cluster-wide scales, where the dark matter gravity, thermal pressure, magnetic fields, and ultrarelativistic particles are at play. In particular, these discontinuities provide the only way to measure the gas bulk velocities in the plane of the sky. The observed temperature jumps at cold fronts require that thermal conduction across the fronts is strongly suppressed. Furthermore, the width of the density jump in the best-studied cold front is smaller than the Coulomb mean free path for the plasma particles. These findings show that transport processes in the intracluster plasma can easily be suppressed. Cold fronts also appear less prone to hydrodynamic instabilities than expected, hinting at the formation of a parallel magnetic field layer via magnetic draping. This may make it difficult to mix different gas phases during a merger. A sharp electron temperature jump across the best-studied shock front has shown that the electron proton

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Vaporization of Deforming Droplets

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  15. 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.

  16. 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).

  17. 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.

  18. 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

  19. 1. View of south front of HiattStricklin House showing front ...

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

    1. View of south front of Hiatt-Stricklin House showing front porch, modern stairs and south porch entry alteration, facing north. - Hiatt Property, House, West bank of Woof Creek, 400 feet northwest of intersection of U.S.F.S. Roads 651 & 349, Placerville, Boise County, ID

  20. 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

  1. 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.

  2. 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.

  3. Nail Deformities and Injuries.

    PubMed

    Tucker, James Rory J

    2015-12-01

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

  4. 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.

  5. 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.

  6. Cold Fronts Research Programme: Progress, Future Plans, and Research Directions.

    NASA Astrophysics Data System (ADS)

    Ryan, B. F.; Wilson, K. J.; Garratt, J. R.; Smith, R. K.

    1985-09-01

    Following the analysis of data collected during Phases land II of the Cold Fronts Research Programme (CFRP) a conceptual model for the Australian summertime "cool change" has been proposed. The model provides a focus and a framework for the design of Phase III.The model is based on data gathered from a mesoscale network centered on Mount Gambier, South Australia, and includes the coastal waters to the west and relatively flat terrain to the east. The first objective of Phase III is to generalize the model so that it is applicable to the ocean waters to the far west of Mount Gambier and to the more rugged terrain farther to the east in the vicinity of Melbourne, Victoria. The remaining objectives concentrate on resolving unsatisfactory aspects of the model such as the evolution of convective lines and the relationship between the surface cold front and the upper-tropospheric cold pool and its associated jet stream.The integrated nature of the Cold Fronts Research Programme has meant that it has stimulated a wide range of research activities that extend beyond the field observations. The associated investigations include climatological, theoretical, and numerical modeling studies.

  7. Positronium in basis light-front quantization

    NASA Astrophysics Data System (ADS)

    Zhao, Xingbo; Wiecki, Paul; Li, Yang; Maris, Pieter; Vary, James

    2014-09-01

    Basis light-front quantization (BLFQ) has been recently developed as a first-principles nonperturbative approach for quantum field theory. Adopting the light-front quantization and Hamiltonian formalism, it solves for the mass eigenstates of quantum field theory as the eigenvalue problem of the associated light-front Hamiltonian. In this work we apply BLFQ to the positronium system in QED and solve for its eigenspectrum in the Fock space with the lowest two Fock sectors included. We explicitly demonstrate our nonperturbative renormalization procedure, in which we infer the various needed renormalization factors through solving a series of parallel single electron problems. We then compare our numerical results for the mass spectrum to the expected Bohr spectrum from nonrelativistic quantum mechanics. Basis light-front quantization (BLFQ) has been recently developed as a first-principles nonperturbative approach for quantum field theory. Adopting the light-front quantization and Hamiltonian formalism, it solves for the mass eigenstates of quantum field theory as the eigenvalue problem of the associated light-front Hamiltonian. In this work we apply BLFQ to the positronium system in QED and solve for its eigenspectrum in the Fock space with the lowest two Fock sectors included. We explicitly demonstrate our nonperturbative renormalization procedure, in which we infer the various needed renormalization factors through solving a series of parallel single electron problems. We then compare our numerical results for the mass spectrum to the expected Bohr spectrum from nonrelativistic quantum mechanics. Supported by DOE (under Grants DESC0008485 SciDAC/NUCLEI, DE-FG02-87ER40371) and NSF (under Grant 0904782).

  8. 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

  9. PIV tracer behavior on propagating shock fronts

    NASA Astrophysics Data System (ADS)

    Glazyrin, Fyodor N.; Mursenkova, Irina V.; Znamenskaya, Irina A.

    2016-01-01

    The present work was aimed at the quantitative particle image velocimetry (PIV) measurement of a velocity field near the front of a propagating shock wave and the study of the dynamics of liquid tracers crossing the shock front. For this goal, a shock tube with a rectangular cross-section (48  ×  24 mm) was used. The flat shock wave with Mach numbers M  =  1.4-2.0 propagating inside the tube channel was studied as well as an expanding shock wave propagating outside the channel with M  =  1.2-1.8 at its main axis. The PIV imaging of the shock fronts was carried out with an aerosol of dioctyl sebacate (DEHS) as tracer particles. The pressures of the gas in front of the shock waves studied ranged from 0.013 Mpa to 0.1 MPa in the series of experiments. The processed PIV data, compared to the 1D normal shock theory, yielded consistent values of wake velocity immediately behind the plain shock wave. Special attention was paid to the blurring of the velocity jump on the shock front due to the inertial particle lag and peculiarities of the PIV technique. A numerical algorithm was developed for analysis and correction of the PIV data on the shock fronts, based on equations of particle-flow interaction. By application of this algorithm, the effective particle diameter of the DEHS aerosol tracers was estimated as 1.03  ±  0.12 μm. A number of different formulations for particle drag were tested with this algorithm, with varying success. The results show consistency with previously reported experimental data obtained for cases of stationary shock waves.

  10. 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.

  11. Mechanism of branching in negative ionization fronts.

    PubMed

    Arrayás, Manuel; Fontelos, Marco A; Trueba, José L

    2005-10-14

    When a strong electric field is applied to nonconducting matter, narrow channels of plasma called streamers may form. Branchlike patterns of streamers have been observed in anode directed discharges. We explain a mechanism for branching as the result of a balance between the destabilizing effect of impact ionization and the stabilizing effect of electron diffusion on ionization fronts. The dispersion relation for transversal perturbation of a planar negative front is obtained analytically when the ratio D between the electron diffusion coefficient and the intensity of the externally imposed electric field is small. We estimate the spacing lambda between streamers and deduce a scaling law lambda approximately D(1/3). PMID:16241810

  12. 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

  13. Deformation twins in Hornblende

    USGS Publications Warehouse

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

    1970-01-01

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

  14. Transfer involving deformed nuclei

    SciTech Connect

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

    1985-03-01

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

  15. 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.

  16. Degenerative Spinal Deformity.

    PubMed

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

    2015-10-01

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

  17. Underwater Landslide Shape, Motion, Deformation, and Tsunami Generation

    NASA Astrophysics Data System (ADS)

    Grilli, S. T.; Watts, P.

    2003-04-01

    We represent underwater landslides with functional forms that describe the shape of an underwater landslide, or submarine mass failure. The chosen mathematical functions are able to reproduce most features of the more complicated landslide shapes output by the model BING. A canonical description of underwater landslide shape is proposed that remains valid throughout mass failure acceleration. The landslide motion is decomposed into center of mass motion and deformation about the center of mass, in traditional engineering fashion. The theoretical center of mass motion is compared to both experimental results of granular mass flows and numerical results from BING. Appropriate values of dynamical coefficients account for added mass effects, hydrodynamic drag, and Coulomb friction, whenever applicable. Landslide motion is scaled by landslide density, length and slope angle. This approach is readily extended to account for real bathymetric cross sections. Landslide deformation is treated as an overall landslide thinning, an overall landslide extension, and as an accumulation of bulk towards the front of the failure. The initial rates of deformation are found from both experimental and numerical work. The mean rates of deformation are found from the length of actual landslide deposits. In both cases, landslide deformation is scaled by the landslide density, length and slope angle. Tsunami generation is simulated with an efficient 2D Boundary Element Method fluid dynamic model. The model enables many different tsunami generation simulations with an absolute free surface accuracy of greater than 1%. A sensitivity analysis is performed for tsunamis generated by a substantial cross-section of the non-dimensional space described by landslide shape, motion, and deformation. Tsunami generation by the model is compared to various experimental results of solid and deforming landslides. In general, it is the center of mass motion that dominates tsunami generation, whereas

  18. Interfacial diffusion aided deformation during nanoindentation

    NASA Astrophysics Data System (ADS)

    Samanta, Amit; E, Weinan

    2016-07-01

    Nanoindentation is commonly used to quantify the mechanical response of material surfaces. Despite its widespread use, a detailed understanding of the deformation mechanisms responsible for plasticity during these experiments has remained elusive. Nanoindentation measurements often show stress values close to a material's ideal strength which suggests that dislocation nucleation and subsequent dislocation activity dominates the deformation. However, low strain-rate exponents and small activation volumes have also been reported which indicates high temperature sensitivity of the deformation processes. Using an order parameter aided temperature accelerated sampling technique called adiabatic free energy dynamics [J. B. Abrams and M. E. Tuckerman, J. Phys. Chem. B, 112, 15742 (2008)], and molecular dynamics we have probed the diffusive mode of deformation during nanoindentation. Localized processes such as surface vacancy and ad-atom pair formation, vacancy diffusion are found to play an important role during indentation. Our analysis suggests a change in the dominant deformation mode from dislocation mediated plasticity to diffusional flow at high temperatures, slow indentation rates and small indenter tip radii.

  19. 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

  20. 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.

  1. Active deformation in the Northern Walker Lane: a detailed geodetic study of the Mohawk Valley and Honey Lake/Warm Springs fault systems

    NASA Astrophysics Data System (ADS)

    Bormann, J. M.; Hammond, W. C.; Kreemer, C. W.; Blewitt, G.

    2012-12-01

    The Mohawk Valley and Honey Lake/Warm Springs faults are parallel, northwest striking, dextral fault systems separated by ~50 km in the westernmost part of the Northern Walker Lane. These two faults work as a cooperative pair to accommodate 3-5 mm/yr of the total 8 mm/yr of right-lateral deformation geodetically observed across the Northern Walker Lane, however it is unclear with fault is dominant. Geologic studies of the faults result in right-lateral slip rates of 1-2.5 mm/yr on the Honey Lake fault and a minimum of 0.3 mm/yr on the Mohawk Valley fault. In contrast, previous geodetic studies estimate slip rates of ~1 mm/yr on the Honey Lake fault and ~3 mm/yr on the Mohawk Valley fault. To reconcile the discrepancy between the distribution of slip on the faults and the differences between sums of the geologically and geodetically estimated slip rates, we use new GPS data to constrain an elastic block model developed specifically to study the Mohawk Valley and Honey Lake/Warm Springs fault systems. We present a dense GPS velocity solution (~10 km average station spacing) that incorporates new data from the semi-continuous Mobile Array of GPS for Nevada Transtension network (MAGNET, http://geodesy.unr.edu/networks) operated by the University of Nevada, Reno with continuous data from the EarthScope Plate Boundary Observatory and other networks. Data collected during the summer of 2012 bring many MAGNET GPS time series in the Northern Walker Lane to near 5 years in duration. The density of our velocity field and recent advances in data processing give us unprecedented precision in the measurement of contemporary deformation in the Northern Walker Lane. We use the velocity solution to solve for slip rates on the companion fault systems and explore the effects of block model geometry assumptions and tradeoffs. Our model predicts slip rates of 2.2±0.3 mm/yr for the Mohawk Valley fault and 1.1±0.2 mm/yr for the Honey Lake fault. Block model slip rate estimates are

  2. 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.

  3. New observations of the active deformation along the oblique collision/subduction boundary zone between the North American and Caribbean plates (northern Hispaniola offshore margin)

    NASA Astrophysics Data System (ADS)

    Carbó-Gorosabel, Andrés; Granja Bruña, José Luis; Rodríguez Zurrunero, Álvaro; Gómez de la Peña, Laura; Muñoz-Martín, Alfonso; Gómez Ballesteros, María; Gorosabel Araus, José Miguel; Espinosa, Salvador; Pazos, Anatonio; Catalán, Manuel; Yamil Rodríguez Asilis, Hector; Nuñez, José Luis; Muñoz, Santiago; ten Brink, Uri S.; Quijano, Jesús; Llanes Estrada, Pilar; Martín Dávila, José; Druet, María

    2015-04-01

    The Caribbean plate is moving relative to the North American plate at a rate of 20.0 ± 0.4 mm/y towards 074° ± 1°. This eastward motion has been taking place during most of the Cenozoic developing a 250 km-wide band of deformation, in which microplate and block tectonics take place. The eastward motion of the Hispaniola block is being impeded relative to the motion of the Caribbean plate's interior due to the collision with the Bahamas banks. This collision has resulted in the development of the Northern Hispaniola deformed belt along the northern Hispaniola offshore margin. A series of large (M6.2-M8.1) thrust earthquakes from 1943-1953, and two significant events in 1994 (M5.6) and 2003 (M6.4) occurred close to the city of Puerto Plata have been attributed to oblique collision/subduction of the North America plate and Bahamas banks beneath the northern Hispaniola. 300 km of 2D multi-channel seismic (MCS) reflection data and approximately 15000 km2 of high-resolution, systematic swath bathymetry data were recorded in the northern Hispaniola offshore margin as part of a larger survey carried out in November-December of 2013 aboard the Spanish R/V Sarmiento de Gamboa. MCS profiles were collected shooting a GI gun array (GGUN-II®) of 1750 ci. every 37.5 m and the signal recorded in a 3000 m-long streamer with 240 channels (Sentinel Sercel®). Differential GPS navigated high-resolution bathymetry data were collected using the hull-mounted Hydrosweep ATLAS DS echo-sounder system. Using new high-resolution multibeam bathymetry and MCS data, combined with previous 2D seismic data, we have studied the along- and across-strike variations of the geomorphology and shallower structure of the northern Hispaniola offshore margin. Here we present preliminary results focused on the identification and characterization of recent tectonic features in the region and provide well-defined targets to carry out future studies for seismic and tsunamigenic hazard assessment.

  4. Atypical occlusion process caused by the merger of a sea-breeze front and gust front

    NASA Astrophysics Data System (ADS)

    Abulikemu, Abuduwaili; Xu, Xin; Wang, Yuan; Ding, Jinfeng; Wang, Yan

    2015-10-01

    An atypical occlusion process that occurred in North China on 14 July 2011 is studied based on both observations and a real-data Weather Research and Forecasting (WRF) model simulation. The results show that this atypical occlusion process was significantly different from the traditional, synoptic-scale occlusion process that occurs within extratropical cyclones. It was caused by the merger of two cold-type mesoscale fronts. One of the fronts developed from the gust front of convective storms, while the other was a sea-breeze front. As the two fronts moved towards each other, the warm air between them was squeezed and separated from the surface. An atypical occluded front was formed when the two fronts merged, with the warm air forced aloft. This kind of occlusion is termed a "merger" process, different from the well-known "catch-up" and "wrap-up" processes. Moreover, local convection was found to be enhanced during the merger process, with severe convective weather produced in the merger area.

  5. 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.

  6. 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.

  7. Motivation and Front-End Analysis.

    ERIC Educational Resources Information Center

    Harless, Joe

    1978-01-01

    Relates Front-End Analysis (FEA) to motivation by categorizing it as either Diagnostic FEA or Planning FEA. The former is used to diagnose existing problems and prescribe motivational programs; the latter assumes that motivational programs must be implemented, along with other programs, to build the optimum environment to support the performance.…

  8. Advocacy on the Front Lines of CTE

    ERIC Educational Resources Information Center

    Reese, Susan

    2011-01-01

    Career and technical education (CTE) in the 21st century is more relevant and rigorous than ever before. It prepares students to compete in the global workplace, it inspires lifelong learning, and it helps prevent at-risk students from dropping out of school because it keeps them engaged in the learning process. Those who work on the front lines…

  9. Teaching Front Handsprings from a Developmental Approach

    ERIC Educational Resources Information Center

    Stork, Steve

    2006-01-01

    The front handspring is an important gymnastics skill that serves as a transition from beginner-level rolling and static balances to more advanced tumbling. It is, therefore, a skill highly desired by beginners. Early learning requires a great deal of effort during which students experience many failed attempts. Unless they are highly motivated,…

  10. QCD and Light-Front Holography

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.

    2010-10-27

    The soft-wall AdS/QCD model, modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics. The model predicts a zero-mass pion for zero-mass quarks and a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number N. Light-Front Holography maps the amplitudes which are functions of the fifth dimension variable z of anti-de Sitter space to a corresponding hadron theory quantized on the light front. The resulting Lorentz-invariant relativistic light-front wave equations are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. The result is to a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryon light-quark bound states, which in turn predict the behavior of the pion and nucleon form factors. The theory implements chiral symmetry in a novel way: the effects of chiral symmetry breaking increase as one goes toward large interquark separation, consistent with spectroscopic data, and the the hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenst