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Terms modified by NW Selected AbstractsGrowth of tin oxide nanocrystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005L. Zanotti Abstract Functional oxides are presently much investigated as regards not only their basic properties, but also their actual and potential applications. Tin oxides appear particularly interesting when grown in nanowire shape (SnO2 -NW) because of their electronic- and sensor-device applications. In this paper the results of a systematic study on nucleation and growth of SnO2 -NWs, when an open-tube vapor-transport technique is employed, are reported and discussed. The vapor transport conditions have been investigated in greater detail and for the first time a growth model is proposed. Functional tests at different temperatures and gaseous compositions have proved that the SnO2 -NW are suitable for the preparation of highly-sensitive and stable gas sensors. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A CdSe Nanowire/Quantum Dot Hybrid Architecture for Improving Solar Cell PerformanceADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Yanghai Yu Abstract Incorporating colloidal CdSe quantum dots (QDs) into CdSe nanowire (NW)-based photoelectrochemical solar cells increases their incident-photon-to-carrier conversion efficiencies (IPCE) from 13% to 25% at 500,nm. While the effect could, in principle, stem from direct absorption and subsequent carrier generation by QDs, the overall IPCE increase occurs across the entire visible spectrum, even at wavelengths where the dots do not absorb light. This beneficial effect originates from an interplay between NWs and QDs where the latter fill voids between interconnected NWs, providing electrically accessible conduits, in turn, enabling better carrier transport to electrodes. The presence of QDs furthermore reduces the residual polarization anisotropy of random NW networks. Introducing QDs therefore addresses an important limiting constraint of NW photoelectrochemical solar cells. The effect appears to be general and may aid the future design and implementation of other NW-based photovoltaics. [source] Growth and Transfer of Monolithic Horizontal ZnO Nanowire Superstructures onto Flexible SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Sheng Xu A method of fabricating horizontally aligned ZnO nanowire (NW) arrays with full control over the width and length is demonstrated. A cross-sectional view of the NWs by transmission electron microscopy shows a "mushroom-like" structure. Novel monolithic multisegment superstructures are fabricated by making use of the lateral overgrowth. Ultralong horizontal ZnO NWs of an aspect ratio on the order of ten thousand are also demonstrated. These horizontal NWs are lifted off and transferred onto a flexible polymer substrate, which may have many great applications in horizontal ZnO NW-based nanosensor arrays, light-emitting diodes, optical gratings, integrated circuit interconnects, and high-output-power alternating-current nanogenerators. [source] Wet and Dry Adhesion Properties of Self-Selective Nanowire ConnectorsADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Hyunhyub Ko Abstract Here, the wet and dry adhesion properties of hybrid Ge/parylene nanowire (NW) connectors are examined. The ability of the NW connectors to bind strongly even under lubricating conditions, such as mineral oil, sheds light on the dominant role of van der Waals interactions in the observed adhesion. The superhydrophobic surface of the NW connectors enables the wet, self-cleaning of contaminant particles from the surface, similar to the lotus effect. In addition, the effect of NW length on the shear adhesion strength, repeated usability, and robustness of the connectors, all critical properties for applications that require reversible binding of components, is examined. [source] Template Deformation-Tailored ZnO Nanorod/Nanowire Arrays: Full Growth Control and Optimization of Field-EmissionADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Haibo Zeng Abstract Here, a facile and effective route toward full control of vertical ZnO nanorod (NR)/nanowire (NW) arrays in centimeter-scale areas and considerable improvement of field-emission (FE) performance is reported. Controlled deformation of colloidal crystal monolayer templates is introduced by heating near glass-transition temperature. The NR/NW density, uniformity, and tapering were all adjusted through selection of template size and deformation, and electrolyte composition. In line with the adjustments, the field-emission performance of the arrays is significantly improved. A low turn-on electric field of 1.8,V µm,1, a field-enhancement factor of up to 5,750, and an emitting current density of up to 2.5,mA cm,2 were obtained. These improved parameters would benefit their potential application in cold-cathode-based electronics. [source] Observation of a 2D Electron Gas and the Tuning of the Electrical Conductance of ZnO Nanowires by Controllable Surface Band-BendingADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Youfan Hu Abstract Direct experimental evidence for the existence of a 2D electron gas in devices based on ZnO nanowires (NWs) is presented. A two-channel core/shell model is proposed for the interpretation of the temperature-dependent current,voltage (I,V) characteristics of the ZnO NW, where a mixed metallic,semiconducting behavior is observed. The experimental results are quantitatively analyzed using a weak-localization theory, and suggest that the NW is composed of a "bulk" semiconducting core with a metallic surface accumulation layer, which is basically a 2D electron gas in which the electron,phonon inelastic scattering is much weaker than the electron,electron inelastic scattering. A series of I,V measurements on a single NW device are carried out by alternating the atmosphere (vacuum, H2, vacuum, O2), and a reversible change in the conductance from metallic to semiconducting is achieved, indicating the surface accumulation layer is likely hydroxide-induced. Such results strongly support the two-channel model and demonstrate the controllable tuning of the ZnO NW electrical behavior via surface band-bending. [source] Structural and Room-Temperature Transport Properties of Zinc Blende and Wurtzite InAs NanowiresADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Shadi A. Dayeh Abstract Here, direct correlation between the microstructure of InAs nanowires (NWs) and their electronic transport behavior at room temperature is reported. Pure zinc blende (ZB) InAs NWs grown on SiO2/Si substrates are characterized by a rotational twin along their growth-direction axis while wurtzite (WZ) InAs NWs grown on InAs (111)B substrates have numerous stacking faults perpendicular to their growth-direction axis with small ZB segments. In transport measurements on back-gate field-effect transistors (FETs) fabricated from both types of NWs, significantly distinct subthreshold characteristics are observed (Ion/Ioff,,,2 for ZB NWs and ,104 for WZ NWs) despite only a slight difference in their transport coefficients. This difference is attributed to spontaneous polarization charges at the WZ/ZB interfaces, which suppress carrier accumulation at the NW surface, thus enabling full depletion of the WZ NW FET channel. 2D Silvaco-Atlas simulations are used for ZB and WZ channels to analyze subthreshold current flow, and it is found that a polarization charge density of ,1013,cm,2 leads to good agreement with experimentally observed subthreshold characteristics for a WZ InAs NW given surface-state densities in the 5,×,1011,5,×,1012,cm,2 range. [source] Palsas in Härjedalen, Sweden: 1910 and 1998 ComparedGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2000Tomas Nihlén In 1998 an area near Helagsfjället in Härjedalen was investigated in an attempt to relocate palsas discovered by the botanist Harry Smith in 1910. Several small palsa-like features with ice cores were detected. The palsas were found on an almost flat peat bog at 950 m, 3 km NW of Helagsfjället. Five clearly elevated mounds and some indistinct ones with palsa-like features were traced. The five mounds were about 0.6 m high and had an area of about 2 × 3 m. One of the mounds was examined in more detail. At a depth of 0.3 m in the peat an ice body with a hard ice core was found. This location is the most southerly area known with occurrence of palsa-like forms in Sweden at the present time. In spite of a warmer climate towards the latter part of this century, palsa-like features have survived in this area. The mean annual temperature barely fits the criterion for palsa formation while the mean annual precipitation is too high as compared with the general assumptions. The palsa formation is probably dependent on strong winds thinning out the snowcover. [source] Extensional development of the Fundy rift basin, southeastern CanadaGEOLOGICAL JOURNAL, Issue 6 2009Martha O. Withjack Abstract The Fundy rift basin of Nova Scotia and New Brunswick, Canada, is part of the Eastern North American rift system that formed during the breakup of Pangaea. Integrated seismic-reflection, field, digital-elevation and aeromagnetic data indicate that the Fundy rift basin underwent two phases of deformation: syn-rift extension followed by post-rift basin inversion. Inversion significantly modified the geometries of the basin and its rift-related structures. In this paper, we remove the effects of inversion to examine the basin's extensional development. The basin consists of three structural subbasins: the Fundy and Chignecto subbasins are bounded by low-angle, NE-striking faults; the Minas subbasin is bounded by E- to ENE-striking faults that are steeply dipping at the surface and gently dipping at depth. Together, these linked faults form the border,fault system of the Fundy rift basin. Most major faults within the border,fault system originated as Palaeozoic contractional structures. All syn-rift units imaged on seismic profiles thicken towards the border,fault system, reflecting extensional movement from Middle Triassic (and possibly Permian) through Early Jurassic time. Intra-rift unconformities, observed on seismic profiles and in the field, indicate that uplift and erosion occurred, at least locally, during rifting. Based on seismic data alone, the displacement direction of the hanging wall of the border,fault system of the Fundy rift basin ranged from SW to SE during rifting. Field data (i.e. NE-striking igneous dykes, sediment-filled fissures and normal faults) indicate NW,SE extension during Early Jurassic time, supporting a SE-displacement direction. With a SE-displacement direction, the NE-striking border,fault zones of the Fundy and Chignecto subbasins had predominantly normal dip slip during rifting, whereas the E-striking border,fault zone of the Minas subbasin had oblique slip with left-lateral and normal components. Sequential restorations of seismic-reflection profiles (coupled with projections from onshore geology) show that the Fundy rift basin underwent 10,20,km of extension, most of which was accommodated by the border,fault system, and was considerably wider and deeper prior to basin inversion. Post-rift deformation tilted the eastern side of the basin to the northwest/north, producing significant uplift and erosion. Copyright © 2009 John Wiley & Sons, Ltd. [source] Stratigraphic and structural evolution of the Blue Nile Basin, Northwestern Ethiopian PlateauGEOLOGICAL JOURNAL, Issue 1 2009N. DS. Abstract The Blue Nile Basin, situated in the Northwestern Ethiopian Plateau, contains ,1400,m thick Mesozoic sedimentary section underlain by Neoproterozoic basement rocks and overlain by Early,Late Oligocene and Quaternary volcanic rocks. This study outlines the stratigraphic and structural evolution of the Blue Nile Basin based on field and remote sensing studies along the Gorge of the Nile. The Blue Nile Basin has evolved in three main phases: (1) pre-sedimentation phase, include pre-rift peneplanation of the Neoproterozoic basement rocks, possibly during Palaeozoic time; (2) sedimentation phase from Triassic to Early Cretaceous, including: (a) Triassic,Early Jurassic fluvial sedimentation (Lower Sandstone, ,300,m thick); (b) Early Jurassic marine transgression (glauconitic sandy mudstone, ,30,m thick); (c) Early,Middle Jurassic deepening of the basin (Lower Limestone, ,450,m thick); (d) desiccation of the basin and deposition of Early,Middle Jurassic gypsum; (e) Middle,Late Jurassic marine transgression (Upper Limestone, ,400,m thick); (f) Late Jurassic,Early Cretaceous basin-uplift and marine regression (alluvial/fluvial Upper Sandstone, ,280,m thick); (3) the post-sedimentation phase, including Early,Late Oligocene eruption of 500,2000,m thick Lower volcanic rocks, related to the Afar Mantle Plume and emplacement of ,300,m thick Quaternary Upper volcanic rocks. The Mesozoic to Cenozoic units were deposited during extension attributed to Triassic,Cretaceous NE,SW-directed extension related to the Mesozoic rifting of Gondwana. The Blue Nile Basin was formed as a NW-trending rift, within which much of the Mesozoic clastic and marine sediments were deposited. This was followed by Late Miocene NW,SE-directed extension related to the Main Ethiopian Rift that formed NE-trending faults, affecting Lower volcanic rocks and the upper part of the Mesozoic section. The region was subsequently affected by Quaternary E,W and NNE,SSW-directed extensions related to oblique opening of the Main Ethiopian Rift and development of E-trending transverse faults, as well as NE,SW-directed extension in southern Afar (related to northeastward separation of the Arabian Plate from the African Plate) and E,W-directed extensions in western Afar (related to the stepping of the Red Sea axis into Afar). These Quaternary stress regimes resulted in the development of N-, ESE- and NW-trending extensional structures within the Blue Nile Basin. Copyright © 2008 John Wiley & Sons, Ltd. [source] Evidence for two episodes of volcanism in the Bigadiç borate basin and tectonic implications for western TurkeyGEOLOGICAL JOURNAL, Issue 5 2005Fuat Erkül Abstract Western Turkey has been dominated by N,S extension since the Early Miocene. The timing and cause of this N,S extension and related basin formation have been the subject of much debate, but new data from the Bigadiç borate basin provide insights that may solve this controversy. The basin is located in the Bornova Flysch Zone, which is thought to have formed as a major NE-trending transform zone during Late Cretaceous-Palaeocene collisional Tethyan orogenesis and later reactivated as a transfer zone of weakness, and which separates two orogenic domains having different structural evolutions. Volcanism in the Bigadiç area is characterized by two rock units that are separated by an angular unconformity. These are: (1) the Kocaiskan volcanites that gives K/Ar ages of 23,Ma, and (2) the Bigadiç volcano-sedimentary succession that yields ages of 20.6 to 17.8,Ma. Both units are unconformably overlain by Upper Miocene-Pliocene continental deposits. The Kocaiskan volcanites are related to the first episode of volcanic activity and comprise thick volcanogenic sedimentary rocks derived from subaerial andesitic intrusions, domes, lava flows and pyroclastic rocks. The second episode of volcanic activity, represented by basaltic to rhyolitic lavas and pyroclastic rocks, accompanied lacustrine,evaporitic sedimentation. Dacitic to rhyolitic volcanic rocks, called the S,nd,rg, volcanites, comprise NE-trending intrusions producing lava flows, ignimbrites, ash-fall deposits and associated volcanogenic sedimentary rocks. Other NE-trending olivine basaltic (Gölcük basalt) and trachyandesitic (Kay,rlar volcanites) intrusions and lava flows were synchronously emplaced into the lacustrine sediments. The intrusions typically display peperitic rocks along their contacts with the sedimentary rocks. It is important to note that the Gölcük basalt described here is the first recorded Early Miocene alkali basalt in western Turkey. The oldest volcanic episode occurred in the NE-trending zone when the region was still experiencing N,S compression. The angular unconformity between the two volcanic episodes marks an abrupt transition from N,S collision-related convergence to N,S extension related to retreat of the Aegean subduction zone to the south along an extensional detachment. Thrust faults with top-to-the-north sense of shear and a series of anticlines and synclines with subvertical NE-striking axial planes observed in the Bigadiç volcano-sedimentary succession suggest that NW,SE compression was reactivated following sedimentation. Geochemical data from the Bigadiç area also support the validity of the extensional regime, which was characterized by a bimodal volcanism related to extrusion of coeval alkaline and calc-alkaline volcanic rocks during the second volcanic episode. The formation of alkaline volcanic rocks dated as 19.7,±,0.4,Ma can be related directly to the onset of the N,S extensional regime in western Turkey. Copyright © 2005 John Wiley & Sons, Ltd. [source] K-Ar age determination, whole-rock and oxygen isotope geochemistry of the post-collisional Bizmi,en and Çalt, plutons, SW Erzincan, eastern Central Anatolia, TurkeyGEOLOGICAL JOURNAL, Issue 4 2005Ayten Önal Abstract Post-collisional granitoid plutons intrude obducted Neo-Tethyan ophiolitic rocks in central and eastern Central Anatolia. The Bizmi,en and Çalt, plutons and the ophiolitic rocks that they intrude are overlain by fossiliferous and flyschoidal sedimentary rocks of the early Miocene Kemah Formation. These sedimentary rocks were deposited in basins that developed at the same time as tectonic unroofing of the plutons along E,W and NW,SE trending faults in Oligo-Miocene time. Mineral separates from the Bizmi,en and Çalt, plutons yield K-Ar ages ranging from 42 to 46,Ma, and from 40 to 49,Ma, respectively. Major, trace, and rare-earth element geochemistry as well as mineralogical and textural evidence reveals that the Bizmi,en pluton crystallized first, followed at shallower depth by the Çalt, pluton from a medium-K calcalkaline, I-type hybrid magma which was generated by magma mixing of coeval mafic and felsic magmas. Delta 18O values of both plutons fall in the field of I-type granitoids, although those of the Çalt, pluton are consistently higher than those of the Bizmi,en pluton. This is in agreement with field observations, petrographic and whole-rock geochemical data, which indicate that the Bizmi,en pluton represents relatively uncontaminated mantle material, whereas the Çalt, pluton has a significant crustal component. Structural data indicating the middle Eocene emplacement age and intrusion into already obducted ophiolitic rocks, suggest a post-collisional extensional origin. However, the pure geochemical discrimination diagrams indicate an arc origin which can be inherited either from the source material or from an upper mantle material modified by an early subduction process during the evolution of the Neo-Tethyan ocean. Copyright © 2005 John Wiley & Sons, Ltd. [source] Present-day stress in the surroundings of 2009 L'Aquila seismic sequence (Italy)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2010Maria Teresa Mariucci SUMMARY The axial zone of the Apenninic belt in central Italy is a tectonically active region affected by post-orogenic Quaternary extension. The present-day stress field is characterized by a minimum horizontal stress (Shmin) , NE,SW oriented, derived mainly from earthquake focal mechanisms and secondarily from borehole breakouts and fault data. The paper describes the computation of the Shmin orientation along two deep boreholes located in the vicinity of the area hit by the 2009 April 6, Mw 6.3 L'Aquila earthquake. The analysed wells show breakout zones at a depth range between 1.4 and 4.6 km, giving precious information on a depth interval usually not investigated by any other data. The results show an Shmin N81 ± 22° and N74 ± 10° oriented for Varoni 1 and Campotosto 1 wells, respectively. The comparison among the breakouts, the 2009 seismic sequence, the past seismicity and the Quaternary faults indicates a small rotation of Shmin orientation from , NE, in the southern, to , ENE in the northern sector of the study area, where the wells are located. These differences are linked both to the natural variations of data and to the orientation of the main tectonic structures varying from NW,SE in the Abruzzi region to , N,S moving toward the Umbro-Marchean Apennines. The identification of constant Shmin orientations with depth derived from all the examined active stress data, confirms the breakouts as reliable stress indicators also for aseismic areas. [source] Spatiotemporal characterization of interswarm period seismicity in the focal area Nový Kostel (West Bohemia/Vogtland) by a short-term microseismic studyGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2009Martin Häge SUMMARY The West Bohemia/Vogtland region is one of the seismically most interesting areas in Europe because of its swarm-like occurrence of seismicity. The installation of the local West Bohemian seismological network (WEBNET) has made the recording of small magnitude seismicity (detection threshold ML,,0.5) possible. We investigated if microseismicity exists below the detection threshold of WEBNET. A microseismic field campaign was carried out in the focal area Nový Kostel. The measurement was performed with three small arrays lasting for 6 d in a seismically quiet, interswarm period. We were able to detect and locate 13 microearthquakes in the magnitude range ,1.5 ,ML,,0.1 and achieved a detection threshold about one magnitude lower than the local network. A relative location suggests that the recorded seismicity is rather related to a specific fault segment than randomly distributed. The determined fault zone is aligned NW,SW and confirms the viability of mapping active faults with short-term measurements. The results demonstrate that a linear extrapolation of the b -value, determined by the network bulletin, down to ML=,0.5 fits well with the amount of our recorded events. [source] 2001 August earthquake swarm at Shadwan Island, Gulf of Suez, EgyptGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2006Ahmed Badawy SUMMARY The earthquake swarm that struck Shadwan Island at the entrance of the Gulf of Suez in 2001 August included 408 events. Almost all of these events (94 per cent) were microearthquakes and only 6 per cent had small measurable magnitudes (5.0 > ML, 3.0). Most of the earthquakes were weak and followed each other so closely in time that they could not be identified at more distant stations. The fault plane solutions of the strongest events of the swarm show almost identical focal mechanisms, predominately normal faulting with a significant sinistral strike-slip component for nodal planes trending NW,SE. A comparison with the mechanisms of the 1969 and 1972 events which took place 20 km north of the swarm epicentral region shows similarities in faulting type and orientation of nodal planes. The azimuths of T -axes determined from focal mechanisms in this study are oriented in the NNE,SSW direction. This direction is consistent with the present-day stress field derived from borehole breakouts in the southern Gulf of Suez and the last phase of stress field changes in the Late Pleistocene, as well as with recent GPS results. The source parameters of the largest (ML, 3.0) events of the 2001 August Shadwan swarm have been estimated from the P -wave spectra of the Egyptian National Seismograph Network (ENSN). Averaging of the values obtained at different stations shows relatively similar source parameters, including a fault length of 0.65 ,L, 2 km, a seismic moment of 7.1 × 1012,Mo, 3.0 × 1014 N m and a stress drop of 0.4 ,,,, 10 bar. [source] The Geysers geothermal field: results from shear-wave splitting analysis in a fractured reservoirGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2005Maya Elkibbi SUMMARY Clear shear-wave splitting (SWS) is observed in 1757 high signal-to-noise ratio microearthquake seismograms recorded by two high density seismic arrays in the NW and the SE Geysers geothermal fields in California. The Geysers reservoir rocks within the study area are largely composed of lithic, low-grade metamorphism, well-fractured metagraywackes which commonly lack schistosity, warranting the general assumption that shear-wave splitting here is induced solely by stress-aligned fracturing in an otherwise isotropic medium. The high quality of observed shear-wave splitting parameters (fast shear-wave polarization directions and time delays) and the generally good data spatial coverage provide an unprecedented opportunity to demonstrate the applicability and limitations of the shear-wave splitting approach to successfully detect fracture systems in the shallow crust based on SWS field observations from a geothermal reservoir. Results from borehole stations in the NW Geysers indicate that polarization orientations range between N and N60E; while in the SE Geysers, ground surface stations show polarization directions that are generally N5E, N35E-to-N60E, N75E-to-N85E, and N20W-to-N55W. Crack orientations obtained from observed polarization orientations are in good agreement with independent field evidence, such as cracks in geological core data, tracer tests, locally mapped fractures, and the regional tectonic setting. Time delays range typically between 8 and 40 ms km,1, indicating crack densities well within the norm of fractured reservoirs. The sizeable collection of high resolution shear-wave splitting parameters shows evidence of prevalent vertical to nearly vertical fracture patterns in The Geysers field. At some locations, however, strong variations of SWS parameters with ray azimuth and incident angle within the shear-wave window of seismic stations indicate the presence of more complex fracture patterns in the subsurface. [source] Fault interactions and subduction tectonics: a re-examination of the Weber, New Zealand, earthquake sequence of 1990GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2003Russell Robinson SUMMARY Two moderate magnitude (Mw= 6.2 and 6.4) earthquakes in the Hikurangi subduction margin, North Island, New Zealand, occurred 3 months apart in 1990. The epicentres are nearly coincident, but the first (Weber 1, primarily normal faulting) occurred within the subducting Pacific Plate (depth about 28 km) and the second (Weber 2, a mix of thrusting and right-lateral motion) occurred within the overlying Australian Plate (depth about 13 km), the plate interface in between. The plate interface is interpreted to be locked trenchward (SE) from about the position of these events, with a transition to aseismic slip further down-dip to the NW. Several stress interaction questions are examined. First, to see whether Weber 1 triggered Weber 2, a range of possible mainshock parameters are used to calculate induced changes in the static Coulomb failure stress (,CFS). In most cases the results are consistent with triggering. Secondly, previous work showed that the rate of aftershock occurrence for Weber 1 decreased markedly about 35 days before Weber 2, recovering afterwards. To see whether aseismic pre-slip on the Weber 2 fault, as predicted by rate and state friction, could be the cause of the decrease, the same fault parameters have been used in reverse. The results are ambiguous, some fault parameters giving results consistent with the hypothesis and others not. The amount of pre-slip required for significant inhibition, however, is about equal to that in the mainshock and distributed over the entire fault plane. Thirdly, observations of episodic, aseismic slip down-dip from locked sections of other plate interfaces are becoming more common. Could such slip have triggered both Weber events? The induced changes in CFS for such slip are uniformly positive on the Weber 1 fault plane, and mostly positive on the Weber 2 fault plane, so the answer is yes. Although there is no independent evidence for aseismic slip prior to the Weber sequence, this case shows that such slip may trigger events on other nearby faults, besides loading the locked section of the plate interface. Static stress triggering considerations are thus likely to be important in subduction environments. [source] Seismic evidence for a mantle plume oceanwards of the Kamchatka,Aleutian trench junctionGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2001A. Gorbatov Summary A non-linear iterative P- wave traveltime tomography has revealed a mantle plume originating at a depth of nearly 1000 km, rising across the 600 km discontinuity, and deflecting subhorizontally in the uppermost mantle presumably by shear flow due to the overlying moving plate. Data from the Geophysical Survey of Russia (1955,1997) were inverted jointly with the catalogues of International Seismological Centre and USGS National Earthquake Information Centre (1964, 1998). The result shows a 300,500 km-wide cylindrical low-velocity anomaly (, , 2 per cent) that extends from a depth of greater than 900 km to shallower than 200 km. The anomaly is almost vertical at depths up to ,400 km and rises obliquely to the north up to ,200 km under the ocean floor near the northern end of Emperor seamounts. Above ,300 km depth a subsidiary anomaly extends subhorizontally to the NW in fair agreement with the direction of movement of the Pacific Plate. The overlying seafloor is characterized by anomalously high heat flow, which may be attributed to the thermal effect of the mantle plume. [source] Seismic activity triggered by the 1999 Izmit earthquake and its implications for the assessment of future seismic riskGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2001Ali Pinar Summary A serious question has remained as to the location of the western end of the main rupture zone associated with the 1999 Izmit, Turkey, earthquake. A clear answer to this question is extremely important for the assessment of future seismic risk in the eastern Marmara Sea region, Turkey. In this paper we show an effective approach to answering this important question, unifying different kinds of information such as seismic activity, focal mechanism solutions and stress changes caused by the main shock into a clear image. We first point out that the major moment release is 1.6 × 1020 N m and covered the area between 29.7°E and 30.5°E and we then claim that the enhanced seismic activity after the main shock in the eastern Marmara Sea region should be regarded as activity triggered by the increase of stress, rather than as aftershock activity along the ruptured zone. We propose three fault segments with an average stress increase on each in the western extension of the main-shock rupture zone as potential sites for future large earthquakes, namely (i) the 50 km long Yalova,Hersek segment (0.45 MPa), (ii) the NW,SE-trending right-lateral strike-slip fault known as the Princes Islands segment (0.18 MPa), and (iii) the Çinarcik,Yalova segment (0.09 MPa) characterized by normal faulting, which was subject to rupture in 1963. [source] The 1994 Sefidabeh earthquakes in eastern Iran: blind thrusting and bedding-plane slip on a growing anticline, and active tectonics of the Sistan suture zoneGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2000M. Berberian Summary In 1994 a sequence of five earthquakes with Mw 5.5,6.2 occurred in the Sistan belt of eastern Iran, all of them involving motion on blind thrusts with centroid depths of 5,10 km. Coseismic ruptures at the surface involved bedding-plane slip on a growing hanging-wall anticline displaying geomorphological evidence of uplift and lateral propagation. The 1994 earthquakes were associated with a NW-trending thrust system that splays off the northern termination of a major N,S right-lateral strike-slip fault. Elevation changes along the anticline ridge suggest that displacement on the underlying thrust dies out to the NW, away from its intersection with the strike-slip fault. This is a common fault configuration in eastern Iran and accommodates oblique NE,SW shortening across the N,S deforming zone, probably by anticlockwise rotations about a vertical axis. This style of fault kinematics may be transitional to a more evolved state that involves partitioning of the strike-slip and convergent motion onto separate subparallel faults. [source] Mass mortality in Northwestern Mediterranean rocky benthic communities: effects of the 2003 heat waveGLOBAL CHANGE BIOLOGY, Issue 5 2009J. GARRABOU Abstract Late in summer 2003, extensive mass mortality of at least 25 rocky benthic macro-invertebrate species (mainly gorgonians and sponges) was observed in the entire Northwestern (NW) Mediterranean region, affecting several thousand kilometers of coastline. We were able to characterize the mortality event by studying six areas covering the main regions of the NW Mediterranean basin. The degree of impact on each study area was quantified at 49 sites by estimating the proportion of colonies affected in populations of several gorgonian species compared with reference data obtained in years without mortality signs. According to these data, the western areas (Catalan coast and Balearic Islands) were the least affected, while the central areas (Provence coast and Corsica-Sardinia) showed a moderate impact. The northernmost and eastern areas (Gulf of Genoa and Gulf of Naples) displayed the highest impact, with almost 80% of gorgonian colonies affected. The heat wave of 2003 in Europe caused an anomalous warming of seawater, which reached the highest temperatures ever recorded in the studied regions, between 1 and 3 °C above the climatic values (mean and maximum). Because this exceptional warming was observed in the depth ranges most affected by the mortality, it seems likely that the 2003 anomalous temperature played a key role in the observed mortality event. A correlation analysis between temperature conditions and degree of impact seems to support this hypothesis. Under the present climate warming trend, new mass mortality events may occur in the near future, possibly driving a major biodiversity crisis in the Mediterranean Sea. [source] Hierarchical Shelled ZnO Structures Made of Bunched Nanowire Arrays,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2007P. Jiang Abstract The size- and morphology-controlled growth of ZnO nanowire (NW) arrays is potentially of interest for the design of advanced catalysts and nanodevices. By adjusting the reaction temperature, shelled structures of ZnO made of bunched ZnO NW arrays are prepared, grown out of metallic Zn microspheres through a wet-chemical route in a closed Teflon reactor. In this process, ZnO NWs are nucleated and subsequently grown into NWs on the surfaces of the microspheres as well as in strong alkali solution under the condition of the pre-existence of zincate (ZnO22,) ions. At a higher temperature (200,°C), three different types of bunched ZnO NW or sub-micrometer rodlike (SMR) aggregates are observed. At room temperature, however, the bunched ZnO NW arrays are found only to occur on the Zn microsphere surface, while double-pyramid-shaped or rhombus-shaped ZnO particles are formed in solution. The ZnO NWs exhibit an ultrathin structure with a length of ca.,,500,nm and a diameter of ca.,10,nm. The phenomenon may be well understood by the temperature-dependent growth process involved in different nucleation sources. A growth mechanism has been proposed in which the degree of ZnO22,saturation in the reaction solution plays a key role in controlling the nucleation and growth of the ZnO NWs or SMRs as well as in oxidizing the metallic Zn microspheres. Based on this consideration, ultrathin ZnO NW cluster arrays on the Zn microspheres are successfully obtained. Raman spectroscopy and photoluminescence measurements of the ultrathin ZnO NW cluster arrays have also been performed. [source] Single-InN-Nanowire Nanogenerator with Upto 1 V Output VoltageADVANCED MATERIALS, Issue 36 2010Chi-Te Huang Piezoelectric potential of a InN nanowire (NW) growing along [0110] can be positive, negative, and zero depending on the direction of the applied transverse force. By measuring the output voltage of a InN-NW-based nanogenerator, about 40% to 55% of output voltages are within the range of -1 and -20 mV, and 25% to 30% of output voltages would exceed -100 mV. Some output voltages could reach the magnitude of -1000 mV, showing its great potential for fabricating high-output nanogenerators. [source] Vertical Epitaxial Co5Ge7 Nanowire and Nanobelt Arrays on a Thin Graphitic Layer for Flexible Field Emission DisplaysADVANCED MATERIALS, Issue 48 2009Hana Yoon Vertically aligned single-crystalline Co5Ge7 nanowire (NW) and nanobelt arrays are grown on a very thin graphite layer as well as a curved graphite layer with a good epitaxial lattice match. Co5Ge7 NW arrays, thus grown, show very efficient field emission properties comparable to those of carbon nanotubes and may be used for flexible field emission displays in the future. [source] Bottom-Imprint Method for VSS Growth of Epitaxial Silicon Nanowire Arrays with an Aluminium CatalystADVANCED MATERIALS, Issue 46 2009Zhang Zhang A bottom-imprint method to fabricate high-quality Si [100] nanowire arrays is described (see figure). This new approach combines the functions of a highly ordered anodic aluminum oxide (AAO) template that acts as both a stamp and a template. Vertically aligned, Al-catalyzed Si nanowire (NW) arrays are grown epitaxially on the Si substrate with a narrow size distribution. [source] Toward the Development of Printable Nanowire Electronics and SensorsADVANCED MATERIALS, Issue 37 2009Zhiyong Fan Abstract In recent years, there has been tremendous progress in the research and development of printable electronics on mechanically flexible substrates based on inorganic active components, which provide high performances and stable device operations at low cost. In this regard, various approaches have been developed for the direct transfer or printing of micro- and nanoscale, inorganic semiconductors on substrates. In this review article, we focus on the recent advancements in the large-scale integration of single crystalline, inorganic-nanowire (NW) arrays for electronic and sensor applications, specifically involving the contact printing of NWs at defined locations. We discuss the advantages, limitations, and the state-of-the-art of this technology, and present an integration platform for future printable, heterogeneous-sensor circuitry based on NW parallel arrays. [source] Functional characterization of human natural killer cells responding to Mycobacterium bovis bacille Calmette-GuérinIMMUNOLOGY, Issue 1 2004Semih Esin Summary The kinetics of activation and induction of several effector functions of human natural killer (NK) cells in response to Mycobacterium bovis bacille Calmette-Guérin (BCG) were investigated. Owing to the central role of monocytes/macrophages (MM) in the initiation and maintenance of the immune response to pathogens, two different experimental culture conditions were analysed. In the first, monocyte-depleted nylon wool non-adherent (NW) cells from healthy donors were stimulated with autologous MM preinfected with BCG (intracellular BCG). In the second, the NW cells were directly incubated with BCG, which was therefore extracellular. In the presence of MM, CD4+ T lymphocytes were the cell subset mainly expressing the activation marker, CD25, and proliferating with a peak after 7 days of culture. In contrast, in response to extracellular BCG, the peak of the proliferative response was observed after 6 days of stimulation, and CD56+ CD3, cells (NK cells) were the cell subset preferentially involved. Such proliferation of NK cells did not require a prior sensitization to mycobacterial antigens, and appeared to be dependent upon contact between cell populations and bacteria. Following stimulation with extracellular BCG, the majority of interferon-, (IFN-,)-producing cells were NK cells, with a peak IFN-, production at 24,30 hr. Interleukin (IL)-2 and IL-4 were not detectable in NK cells or in CD3+ T lymphocytes at any time tested. IL-12 was not detectable in the culture supernatant of NW cells stimulated with extracellular BCG. Compared to the non-stimulated NW cells, the NW cells incubated for 16,20 hr with BCG induced the highest levels of expression of apoptotic/death marker on the NK-sensitive K562 cell line. BCG also induced expression of the activation marker, CD25, and proliferation, IFN-, production and cytotoxic activity, on negatively selected CD56+ CD3, cells. Altogether, the results of this study demonstrate that extracellular mycobacteria activate several NK-cell functions and suggest a possible alternative mechanism of NK-cell activation as the first line of defence against mycobacterial infections. [source] HISTALP,historical instrumental climatological surface time series of the Greater Alpine RegionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2007Ingeborg Auer This paper describes the HISTALP database, consisting of monthly homogenised records of temperature, pressure, precipitation, sunshine and cloudiness for the ,Greater Alpine Region' (GAR, 4,19°E, 43,49°N, 0,3500m asl). The longest temperature and air pressure series extend back to 1760, precipitation to 1800, cloudiness to the 1840s and sunshine to the 1880s. A systematic QC procedure has been applied to the series and a high number of inhomogeneities (more than 2500) and outliers (more than 5000) have been detected and removed. The 557 HISTALP series are kept in different data modes: original and homogenised, gap-filled and outlier corrected station mode series, grid-1 series (anomaly fields at 1° × 1°, lat × long) and Coarse Resolution Subregional (CRS) mean series according to an EOF-based regionalisation. The leading climate variability features within the GAR are discussed through selected examples and a concluding linear trend analysis for 100, 50 and 25-year subperiods for the four horizontal and two altitudinal CRSs. Among the key findings of the trend analysis is the parallel centennial decrease/increase of both temperature and air pressure in the 19th/20th century. The 20th century increase (+1.2 °C/+ 1.1 hPa for annual GAR-means) evolved stepwise with a first peak near 1950 and the second increase (1.3 °C/0.6hPa per 25 years) starting in the 1970s. Centennial and decadal scale temperature trends were identical for all subregions. Air pressure, sunshine and cloudiness show significant differences between low versus high elevations. A long-term increase of the high-elevation series relative to the low-elevation series is given for sunshine and air pressure. Of special interest is the exceptional high correlation near 0.9 between the series on mean temperature and air pressure difference (high-minus low-elevation). This, further developed via some atmospheric statics and thermodynamics, allows the creation of ,barometric temperature series' without use of the measures of temperature. They support the measured temperature trends in the region. Precipitation shows the most significant regional and seasonal differences with, e.g., remarkable opposite 20th century evolution for NW (9% increase) versus SE (9% decrease). Other long- and short-term features are discussed and indicate the promising potential of the new database for further analyses and applications. Copyright © 2006 Royal Meteorological Society. [source] Changes in spring weather conditions and atmospheric circulation in Estonia (1955,95)INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2003Sirje Keevallik Abstract An analysis has been undertaken at Tiirikoja Meteorological Station to investigate changes in the main weather elements in late winter and spring during the period 1955,95. The relationship between these changes and the trends in the atmospheric circulation above Estonia have also been analysed. The latter was estimated from wind speed and direction data recorded at Tallinn Aerological Station at two isobaric levels (500 and 850 hPa). These data permitted the analysts to calculate zonal and meridional components of wind velocity at both levels. Linear trends were fitted to time series of monthly averages of all parameters under consideration. The results indicate that significant changes in meteorological parameters took place in March. These changes are statistically related to the changes in the average airflow in the free atmosphere above Estonia. In March the wind speed at the 500 and 850 hPa isobaric levels increased and the average airflow turned from WNW or NW to SW or WSW. Such changes in the atmospheric circulation can only partly be attributed to the intensification of the North Atlantic oscillation. Copyright © 2003 Royal Meteorological Society [source] Linear and non-linear optimization models for allocation of a limited water supply,IRRIGATION AND DRAINAGE, Issue 1 2004Bijan Ghahraman optimisation de l'irrigation; déficit d'irrigation; Iran Abstract One partial solution to the problem of ever-increasing demands on our water resources is optimal allocation of available water. A non-linear programming (NLP) optimization model with an integrated soil water balance was developed. This model is the advanced form of a previously developed one in which soil water balance was not included. The model also has the advantage of low computer run-time, as compared to commonly used dynamic programming (DP) models that suffer from dimensionality. The model can perform over different crop growth stages while taking into account an irrigation time interval in each stage. Therefore, the results are directly applicable to real-world conditions. However, the time trend of actual evapotranspiration (AET) for individual time intervals fluctuates more than that for growth-stage AETs. The proposed model was run for the Ardak area (45,km NW of the city of Mashhad, Iran) under a single cropping cultivation (corn) as well as a multiple cropping pattern (wheat, barley, corn, and sugar beet). The water balance equation was manipulated with net applied irrigation water to overcome the difficulty encountered with incorrect deep percolation. The outputs of the model, under the imposed seasonal irrigation water shortages, were compared with the results obtained from a simple NLP model. The differences between these two models (simple and integrated) became more significant as irrigation water shortage increased. Oversimplified assumptions in the previous simple model were the main causes of these differences. Copyright © 2004 John Wiley & Sons, Ltd. L'allocation optimale des ressources d'eau disponibles est une réponse partielle au problème de la demande sans cesse croissante de consommation d'eau. Un modèle d'optimisation à programmation non linéaire (NLP) qui intègre un bilan hydrique a été développé. Ce modèle est une version avancée d'un modéle précédent qui n'intégrait pas ce bilan hydrique. Il présente l'avantage de nécessiter moins de puissance informatique en comparaison des modèles à programmation dynamique (DP) généralement utilisés. Le modèle peut s'appliquer à différentes étapes de la croissance des cultures et prend en compte des fréquences d'irrigation variables. Ainsi, les résultats sont directement applicables aux conditions réelles. Le modèle proposé a été utilisé sur une seule culture (maïs) dans la région d'Ardak à 45,km nord-ouest de Mashad, Iran, et sur de multiples cultures (blé, orge, maïs, betterave sucrière). L'équation de bilan hydrique a été calibrée pour maîtriser les difficultés rencontrées avec des mesures d'infiltration incorrectes. Les résultats du modèle, dans le cadre de restrictions d'irrigation saisonnière imposées, ont été comparés avec ceux obtenus par un modèle simple NLP. Les différences entre ces deux modèles (simple et intégré) deviennent plus significatives à mesure que les restrictions d'irrigation augmentent. Les hypothèses trop simplistes du modèle simple sont la cause de ces différences. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||