bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatiotemporal variations of the slow slip event between 2008 and 2013 in the southcentral Alaska subduction zone
Authors: Fu Yuning , Liu Zhen , Freymueller Jeffrey T.
Published: July 2015

We apply a Kalman filter‐based time‐dependent slip inversion method to model a long‐term Slow Slip Event (SSE) in the southcentral Alaska subduction zone from 2008 to 2013. This event occurred downdip of the asperity that ruptured in the 1964 earthquake, the same part of plate interface that slipped during a previous SSE between 1998 and 2001. Most of the slip deficit that accumulated during the steady period between 2001 and 2008 (8 years total) in the SSE source region was released by this SSE. Our results indicate both lateral and downdip propagation during this event. The SSE started at the end of 2008 at the upper section of the slip patch, and gradually propagated to the east and to the deeper part of the interface. Our results indicate no connection between this SSE in Upper Cook Inlet and another SSE in Lower Cook Inlet that started in 2010. Analysis of the earthquake catalog in the southcentral Alaska subduction zone shows a clear increase in seismicity associated with the 2008–2013 SSE. With the data from a newly available continuous GPS site, we now can better constrain the start time of the 1998–2001 SSE as ∼1998.58.
Rainfall thresholds for the precipitation of carbonate and evaporite minerals in modern lakes in northern China
Authors: Gu Ning , Jiang Wenying , Wang Luo , Zhang Enlou , Yang Shiling , Xiong Shangfa
Published: July 2015

Authigenic carbonate and evaporite minerals in lake sediments are widely used to qualitatively reconstruct climate. However, uncertainties still remain about their quantitative relationship to climate. Here we investigate 86 modern lakes in northern China to examine the relationships between mineral formation, lake water chemistry, and climate. The results show that from east to west, with increasing salinity and ionic concentration, calcite, dolomite, and evaporite minerals (gypsum and halite) occur in sequence. Their eastern boundaries approximate modern isohyets, and we define for the first time rainfall thresholds of 600 mm, 400 mm, and 350 mm for the formation of calcite, dolomite, and evaporite minerals, respectively. Since the 400 mm and 600 mm isohyets also coincide with vegetation boundaries, our findings enable a new approach for the quantitative reconstruction of paleoprecipitation and paleovegetation based on mineral analysis.
Evolution of unrest at Laguna del Maule volcanic field (Chile) from InSAR and GPS measurements, 2003 to 2014
Authors: Le Mével Hélène , Feigl Kurt L. , Córdova Loreto , DeMets Charles , Lundgren Paul
Published: July 2015

The Laguna del Maule (LdM) volcanic field in the southern volcanic zone of the Chilean Andes exhibits a large volume of rhyolitic material erupted during postglacial times (20–2 ka). Since 2007, LdM has experienced an unrest episode characterized by high rates of deformation. Analysis of new GPS and Interferometric Synthetic Aperture Radar (InSAR) data reveals uplift rates greater than 190 mm/yr between January 2013 and November 2014. The geodetic data are modeled as an inflating sill at depth. The results are used to calculate the temporal evolution of the vertical displacement. The best time function for modeling the InSAR data set is a double exponential model with rates increasing from 2007 through 2010 and decreasing slowly since 2010. We hypothesize that magma intruding into an existing silicic magma reservoir is driving the surface deformation. Modeling historical uplift at Yellowstone, Long Valley, and Three Sisters volcanic fields suggests a common temporal evolution of vertical displacement rates.
Observations of coincident EMIC wave activity and duskside energetic electron precipitation on 18–19 January 2013
Authors: Blum L. W. , Halford A. , Millan R. , Bonnell J. W. , Goldstein J. , Usanova M. , Engebretson M. , Ohnsted M. , Reeves G. , Singer H. , Clilverd M. , Li X.
Published: July 2015

Electromagnetic ion cyclotron (EMIC) waves have been suggested to be a cause of radiation belt electron loss to the atmosphere. Here simultaneous, magnetically conjugate measurements are presented of EMIC wave activity, measured at geosynchronous orbit and on the ground, and energetic electron precipitation, seen by the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) campaign, on two consecutive days in January 2013. Multiple bursts of precipitation were observed on the duskside of the magnetosphere at the end of 18 January and again late on 19 January, concurrent with particle injections, substorm activity, and enhanced magnetospheric convection. The structure, timing, and spatial extent of the waves are compared to those of the precipitation during both days to determine when and where EMIC waves cause radiation belt electron precipitation. The conjugate measurements presented here provide observational support of the theoretical picture of duskside interaction of EMIC waves and MeV electrons leading to radiation belt loss.
Time‐varying ionosonde trend: Case study of Sodankylä hmF2 data 1957–2014
Authors: Roininen Lassi , Laine Marko , Ulich Thomas
Published: July 2015

We discuss trend analysis of nonstationary ionosonde hmF2 time series measured at Sodankylä Geophysical Observatory (67.4∘N, 26.7∘E), Finland, 1957–2014. We model the hmF2 with a dynamic regression time series model with the following components: a slowly varying background level, seasonal variations, and solar effects. We analyze the time series with a dynamic linear state space model. Such an approach allows model components to vary in time, allowing us to study the dynamic stochastic nature of the underlying long‐term trend. This feature is lacking in most time series models used in atmospheric and environmental long‐term trend analyses. Our objective is to understand the long‐term hmF2 trend with respect to increased levels of carbon dioxide and methane in the atmosphere. Based on model estimates, this phenomenon is predicted to cool the thermosphere and leads to decrease of the altitude of the so‐called F2 layer peak. After accounting for the effects of solar activity variations on the data, we see that the estimated trend shows an almost 30 km decrease of the F2 layer peak during the observation period. The decrease of the peak during 1990–2010 is significantly greater than during earlier observation period.
Improving solar wind modeling at Mercury: Incorporating transient solar phenomena into the WSA‐ENLIL model with the Cone extension
Authors: Dewey Ryan M. , Baker Daniel N. , Anderson Brian J. , Benna Mehdi , Johnson Catherine L. , Korth Haje , Gershman Daniel J. , Ho George C. , McClintock William E. , Odstrcil Dusan , Philpott Lydia C. , Raines Jim M. , Schriver David , Slavin James A. , Solomon Sean C. , Winslow Reka M. , Zurbuchen Thomas H.
Published: July 2015

Coronal mass ejections (CMEs) and other transient solar phenomena play important roles in magnetospheric and exospheric dynamics. Although a planet may interact only occasionally with the interplanetary consequences of these events, such transient phenomena can result in departures from the background solar wind that often involve more than an order of magnitude greater ram pressure and interplanetary electric field applied to the planetary magnetosphere. For Mercury, an order of magnitude greater ram pressure combined with high Alfvén speeds and reconnection rates can push the magnetopause essentially to the planet's surface, exposing the surface directly to the solar wind flow. In order to understand how the solar wind interacts with Mercury's magnetosphere and exosphere, previous studies have used the Wang‐Sheeley‐Arge (WSA)‐ENLIL solar wind modeling tool to calculate basic and composite solar wind parameters at Mercury's orbital location. This model forecasts only the background solar wind, however, and does not include major transient events. The Cone extension permits the inclusion of CMEs and related solar wind perturbations and thus enables characterization of the effects of strong solar wind disturbances on the Mercury system. The Cone extension is predicated on the assumption of constant angular and radial velocities of CMEs to integrate these phenomena into the WSA‐ENLIL coupled model. Comparisons of the model results with observations by the MESSENGER spacecraft indicate that the WSA‐ENLIL+Cone model more accurately forecasts total solar wind conditions at Mercury and has greater predictive power for magnetospheric and exospheric processes than the WSA‐ENLIL model alone.
Latitudinal dependence of short timescale fluctuations during intense geomagnetic storms: A permutation entropy approach
Authors: De Michelis Paola , Consolini Giuseppe , Tozzi Roberta
Published: July 2015

The present study is focused on the analysis of the latitudinal dependence of complexity degree of the short timescale geomagnetic field fluctuations during four intense geomagnetic storms occurring between 2000 and 2003. The aim is that of investigating the qualitative and quantitative changes in the dynamical properties of the magnetospheric system during magnetically disturbed periods. We analyze the short timescale fluctuations (<120 min) of the horizontal component of the Earth's magnetic field at nine different geomagnetic observatories from 49°N magnetic latitude (MLat) to 87°N MLat, by filtering the signal via empirical mode decomposition and successively by applying the permutation entropy analysis to the filtered time series. We show that some properties of the geomagnetic fluctuations during the selected periods are the result of dynamical changes in the magnetospheric system response to the solar wind changes and that these geomagnetic fluctuations display a complex character during the geomagnetic storm development. This evidence supports the idea that the geomagnetic storm nature may be the result of a cooperative and collective dynamics. We also find that the permutation entropy values change with latitude suggesting a latitudinal dependence of the complexity degree of the signals.
Crustal deformation in the New Madrid seismic zone and the role of postseismic processes
Authors: Boyd Oliver S. , Smalley Robert , Zeng Yuehua
Published: July 2015

Global Navigation Satellite System data across the New Madrid seismic zone (NMSZ) in the central United States over the period from 2000 through 2014 are analyzed and modeled with several deformation mechanisms including the following: (1) creep on subsurface dislocations, (2) postseismic frictional afterslip and viscoelastic relaxation from the 1811–1812 and 1450 earthquakes in the NMSZ, and (3) regional strain. In agreement with previous studies, a dislocation creeping at about 4 mm/yr between 12 and 20 km depth along the downdip extension of the Reelfoot fault reproduces the observations well. We find that a dynamic model of postseismic frictional afterslip from the 1450 and February 1812 Reelfoot fault events can explain this creep. Kinematic and dynamic models involving the Cottonwood Grove fault provide minimal predictive power. This is likely due to the smaller size of the December 1811 event on the Cottonwood Grove fault and a distribution of stations better suited to constrain localized strain across the Reelfoot fault. Regional compressive strain across the NMSZ is found to be less than 3 × 10−9/yr. If much of the present‐day surface deformation results from afterslip, it is likely that many of the earthquakes we see today in the NMSZ are aftershocks from the 1811–1812 New Madrid earthquakes. Despite this conclusion, our results are consistent with observations and models of intraplate earthquake clustering. Given this and the recent paleoseismic history of the region, we suggest that seismic hazard is likely to remain significant.
Effects of healing on the seismogenic potential of carbonate fault rocks: Experiments on samples from the Longmenshan Fault, Sichuan, China
Authors: Chen Jianye , Verberne Berend A. , Spiers Christopher J.
Published: July 2015

Fault slip and healing history may crucially affect the fault seismogenic potential in the earthquake nucleation regime. Here we report direct shear friction tests on simulated gouges derived from a carbonate fault breccia, and from a clay/carbonate fault‐core gouge, retrieved from a surface exposure of the Longmenshan Fault Zone (LFZ) which hosted the 2008 Wenchuan earthquake. The experiments were conducted under dry and hydrothermal conditions, at temperatures up to 140°C, at an effective normal stress of 50 MPa, and involved sequential velocity‐stepping (VS), slide‐hold‐slide (SHS), and velocity‐stepping stages. Dry tests performed on breccia‐derived samples showed no dependence of (quasi) steady state friction (μss) on SHS or VS history, and a log linear relation between transient peak healing (Δμpk) and hold time, or classical “Dieterich‐type” healing behavior. By contrast, all experiments conducted under hydrothermal conditions were characterized by “non‐Dieterich” healing behavior. This included (1) an increase in μss upon resliding after a hold period and (2) an increase in friction rate parameter (a − b), after SHS testing. Comparison with previous results suggests that the healing behavior seen in our wet tests may be attributed to solution transfer processes occurring during hold periods. Our findings imply that the shallow portions of faults with carbonate/clay‐rich cores (e.g., the LFZ) can heal much faster than previously recognized, while the upper limit of the seismogenic zone may migrate to deeper levels during interseismic periods. These effects have important implications for understanding the seismic cycle in tectonically active carbonate terrains.
Resolution analysis by random probing
Authors: Fichtner Andreas , Leeuwen Tristan van
Published: July 2015

We develop and apply methods for resolution analysis in tomography, based on stochastic probing of the Hessian or resolution operators. Key properties of our methods are (i) low algorithmic complexity and easy implementation, (ii) applicability to any tomographic technique, including full‐waveform inversion and linearized ray tomography, (iii) applicability in any spatial dimension and to inversions with a large number of model parameters, (iv) low computational costs that are mostly a fraction of those required for synthetic recovery tests, and (v) the ability to quantify both spatial resolution and interparameter trade‐offs. Using synthetic full‐waveform inversions as benchmarks, we demonstrate that autocorrelations of random‐model applications to the Hessian yield various resolution measures, including direction‐ and position‐dependent resolution lengths and the strength of interparameter mappings. We observe that the required number of random test models is around five in one, two, and three dimensions. This means that the proposed resolution analyses are not only more meaningful than recovery tests but also computationally less expensive. We demonstrate the applicability of our method in a 3‐D real‐data full‐waveform inversion for the western Mediterranean. In addition to tomographic problems, resolution analysis by random probing may be used in other inverse methods that constrain continuously distributed properties, including electromagnetic and potential‐field inversions, as well as recently emerging geodynamic data assimilation.
Realizing a terrestrial reference frame using the Global Positioning System
Authors: Haines Bruce J. , Bar‐Sever Yoaz E. , Bertiger Willy I. , Desai Shailen D. , Harvey Nate , Sibois Aurore E. , Weiss Jan P.
Published: July 2015

We describe a terrestrial reference frame (TRF) realization based on Global Positioning System (GPS) data alone. Our approach rests on a highly dynamic, long‐arc (9 day) estimation strategy and on GPS satellite antenna calibrations derived from Gravity Recovery and Climate Experiment and TOPEX/Poseidon low Earth orbit receiver GPS data. Based on nearly 17 years of data (1997–2013), our solution for scale rate agrees with International Terrestrial Reference Frame (ITRF)2008 to 0.03 ppb yr−1, and our solution for 3‐D origin rate agrees with ITRF2008 to 0.4 mm yr−1. Absolute scale differs by 1.1 ppb (7 mm at the Earth's surface) and 3‐D origin by 8 mm. These differences lie within estimated error levels for the contemporary TRF.
Plankton dynamics in a cyclonic eddy in the Southern California Current System
Authors: Chenillat Fanny , Franks Peter J. S. , Rivière Pascal , Capet Xavier , Grima Nicolas , Blanke Bruno
Published: July 2015

The California Current System is an eastern boundary upwelling system (EBUS) with high biological production along the coast. Oligotrophic offshore waters create cross‐shore gradients of biological and physical properties, which are affected by intense mesoscale eddy activity. The influence of eddies on ecosystem dynamics in EBUS is still in debate. To elucidate the mechanisms that influence the dynamics of ecosystems trapped in eddies, and the relative contribution of horizontal and vertical advection in determining local production, we analyze a particular cyclonic eddy using Lagrangian particle‐tracking analyses of numerical Eulerian. The eddy formed in a coastal upwelling system; coastal waters trapped in the eddy enabled it to leave the upwelling region with high concentrations of plankton and nutrients. The ecosystem was initially driven mainly by recycling of biological material. As the eddy moved offshore, production in its core was enhanced compared to eddy exterior waters through Ekman pumping of nitrate from below the euphotic zone; this Ekman pumping was particularly effective due to the shallow nitracline in the eddy compared to eddy exterior waters. Both eddy trapping and Ekman pumping helped to isolate and maintain the ecosystem productivity in the eddy core. This study shows the importance of cyclonic eddies for biological production in EBUS: they contribute both to the redistribution of the coastal upwelling ecosystem and are local regions of enhanced new production. Together, these processes impact cross‐shore gradients of important biological properties.
Temporal and radiometric statistics on lightning flashes observed from space with the ISUAL spectrophotometer
Authors: Offroy Marc , Farges Thomas , Kuo Cheng Ling , Chen Alfred Bing‐Chih , Hsu Rue‐Ron , Su Han‐Tzong , Takahashi Yukihiro , Mende Stephen B. , Frey Harald U.
Published: July 2015

The Imager of Sprites and Upper Atmospheric Lightning (ISUAL) on the FORMOSAT‐2 satellite was launched in 2004 and records transient luminous events (TLEs). ISUAL is an instrument composed of an imager and a multichannel spectrophotometer which is able to measure the brightness from far ultraviolet to near infrared for TLEs and lightning flashes. Several types of TLEs have been identified, classified, and documented between 2004 and 2014. However, no statistical analyses on lightning have already been realized. In this paper, we focus on lightning flashes which did not induce TLEs. Statistics about brightness or temporal dynamic are presented from fitted waveforms from far ultraviolet to near infrared, after having corrected for atmospheric effects for each spectrophotometer channels. We demonstrate that the lightning/satellite distance and the altitude of the lightning need to be taken into account. The lightning waveforms from each spectrophotometer channel could be modeled as an exponential pulsed function which the shape could be explained by the photon propagation in the cloud. The median values at 777.4 nm are 1.63 × 10−6 W m−2 for the maximum brightness, 5.85 × 104 J for the total energy at the source, 414 µs for the full width half maximum, 620 µs for the full width at quarter of maximum, and 170 µs for the risetime. Results are compared with previous experiments performed from visible to near‐infrared domains. The median temporal variables for near‐infrared waveforms are shorter than the values of the UV waveforms.
A Thermodynamic, kinematic and microphysical analysis of a jet and gigantic jet‐producing Florida thunderstorm
Authors: Lazarus S. M. , Splitt M. E. , Brownlee James , Spiva Nicholas , Liu Ningyu
Published: July 2015

This paper presents a meteorological analysis of a storm that produced two jets, four gigantic jets (GJ), and a starter, which were observed by two radars as well as the Kennedy Space Center 4‐Dimensional Lightning Surveillance System on 3 August 2013 in Central Florida. The work is the first application of dual polarization data to a jet‐producing storm and is the fifth case related to a tropical disturbance. The storm environment is consistent with the moist tropical paradigm that characterizes about three quarters of the surface and aircraft observed jet and GJ events. The most unstable (MU) convective available potential energy is not unusual for Florida summer convection and is below the climatological mean for these events. An unusual speed shear layer is located near the storm equilibrium level (EL) and the storm exhibits a tilted structure with CGs displaced upshear. The turbulence, as measured by the eddy dissipation rate, is extreme near the storm top during the event window, consistent with the GJ mixing hypothesis. The individual events are collocated with, and track along, the center axis of the divergent outflow at the EL and occur within the region of the coldest GOES IR temperatures—placing the events within the overshoot. The dual polarization data indicate a deep graupel column, extending above the mixed phase layer, to a 13 km altitude.
Modeling the thermal and physical evolution of Mount Sharp's sedimentary rocks, Gale Crater, Mars: Implications for diagenesis on the MSL Curiosity rover traverse
Authors: Borlina Cauê S. , Ehlmann Bethany L. , Kite Edwin S.
Published: July 2015

Gale Crater, the Mars Science Laboratory (MSL) landing site, contains a central mound, named Aeolis Mons (informally Mount Sharp) that preserves 5 km of sedimentary stratigraphy. Formation scenarios include (1) complete filling of Gale Crater followed by partial sediment removal or (2) building of a central deposit with morphology controlled by slope winds and only incomplete sedimentary fill. Here we model temperature‐time paths for both scenarios, compare results with analyses provided by MSL Curiosity, and provide scenario‐dependent predictions of temperatures of diagenesis along Curiosity's future traverse. The effects of variable sediment thermal conductivity and historical heat flows are also discussed. Modeled erosion and deposition rates are 5–37 µm/yr, consistent with previously published estimates from other Mars locations. The occurrence and spatial patterns of diagenesis depend on sedimentation scenario and surface paleotemperature. For (1) temperatures experienced by sediments decrease monotonically along the traverse and up Mount Sharp stratigraphy, whereas for (2) temperatures increase along the traverse reaching maximum temperatures higher up in Mount Sharp's lower units. If early Mars surface temperatures were similar to modern Mars (mean: −50°C), only select locations under select scenarios permit diagenetic fluids. In contrast, if early Mars surface temperatures averaged 0°C or brines had lowered freezing points, diagenesis is predicted in most locations with temperatures < 225°C. Comparing our predictions with future MSL results on diagenetic textures, secondary mineral assemblages, and their spatial variability will constrain past heat flow, Mount Sharp's formation processes, the availability of liquid water on early Mars, and sediment organic preservation potential.
Tropical cyclone flow asymmetries induced by a uniform flow revisited
Authors: Thomsen Gerald L. , Smith Roger K. , Montgomery Michael T.
Published: July 2015

We investigate the hypothesized effects of a uniform flow on the structural evolution of a tropical cyclone using a simple idealized, three‐dimensional, convection‐permitting, numerical model. The study addresses three outstanding basic questions concerning the effects of moist convection on the azimuthal flow asymmetries and provides a bridge between the problem of tropical cyclone intensification in a quiescent environment and that in vertical shear over a deep tropospheric layer. At any instant of time, explicit deep convection in the model generates flow asymmetries that tend to mask the induced flow asymmetries predicted by the dry, slab boundary layer model of Shapiro, whose results are frequently invoked as a benchmark for characterizing the boundary layer‐induced vertical motion for a translating storm. In sets of ensemble experiments in which the initial low‐level moisture field is randomly perturbed, time‐averaged ensemble mean fields in the mature stage show a coherent asymmetry in the vertical motion rising into the eyewall and in the total (horizontal) wind speed just above the boundary layer. The maximum ascent occurs about 45° to the left of the vortex motion vector, broadly in support of Shapiro's results, in which it occurs ahead of the storm, and consistent with one earlier more complex numerical calculation by Frank and Ritchie. The total wind asymmetry just above the boundary layer has a maximum in the forward right sector, which is in contrast to the structure effectively prescribed by Shapiro based on an inviscid dry symmetric vortex translating in a uniform flow where, in an Earth‐relative frame, the maximum is on the right.
Wavelet‐based analogous phase scintillation index for high latitudes
Authors: Ahmed A. , Tiwari R. , Strangeways H. J. , Dlay S. , Johnsen M. G.
Published: July 2015

The Global Positioning System (GPS) performance at high latitudes can be severely affected by the ionospheric scintillation due to the presence of small‐scale time‐varying electron density irregularities. In this paper, an improved analogous phase scintillation index derived using the wavelet‐transform‐based filtering technique is presented to represent the effects of scintillation regionally at European high latitudes. The improved analogous phase index is then compared with the original analogous phase index and the phase scintillation index for performance comparison using 1 year of data from Trondheim, Norway (63.41°N, 10.4°E). This index provides samples at a 1 min rate using raw total electron content (TEC) data at 1 Hz for the prediction of phase scintillation compared to the scintillation monitoring receivers (such as NovAtel Global Navigation Satellite Systems Ionospheric Scintillation and TEC Monitor receivers) which operate at 50 Hz rate and are thus rather computationally intensive. The estimation of phase scintillation effects using high sample rate data makes the improved analogous phase index a suitable candidate which can be used in regional geodetic dual‐frequency‐based GPS receivers to efficiently update the tracking loop parameters based on tracking jitter variance.
Space Weather Concerns for All‐Electric Propulsion Satellites
Authors: Horne Richard B. , Pitchford David
Published: July 2015

The introduction of all‐electric propulsion satellites is a game changer in the quest for low‐cost access to space. It also raises new questions for satellite manufacturers, operators, and the insurance industry regarding the general risks and specifically the threat of adverse space weather. The issues surrounding this new concept were discussed by research scientists and up to 30 representatives from the space industry at a special meeting at the European Space Weather Week held in November 2014. Here we report on the discussions at that meeting. We show that for a satellite undergoing electric orbit raising for 200 days the radiation dose due to electrons is equivalent to approximately 6.7 year operation at geostationary orbit or approximately half the typical design life. We also show that electrons can be injected into the slot region (8000 km) where they pose a risk of satellite internal charging. The results highlight the importance of additional radiation protection. We also discuss the benefits, the operational considerations, the other risks from the Van Allen radiation belts, the new business opportunities for space insurance, and the need for space situation awareness in medium Earth orbit where electric orbit raising takes place.
The relative stability of salmon redds and unspawned streambeds
Authors: Buxton Todd H. , Buffington John M. , Yager Elowyn M. , Hassan Marwan A. , Fremier Alexander K.
Published: July 2015

Where female salmon build nests (“redds”), streambed material is mixed, fine sediment is winnowed, and bed material is moved into a tailspill mound resembling the shape of a dune. Completed redd surfaces are coarser and better sorted than unspawned beds, which is thought to increase redd stability because larger grains are heavier and harder to move, and sorting increases friction angles for mobility. However, spawning also loosens sediment and creates topography that accelerates flow, which can increase particle mobility. We address these factors controlling the relative stability of redds and unspawned beds in flume experiments where redds were constructed with a dynamic technique that mimics the nesting behavior of female salmon. Although redds exhibited relatively coarse surfaces, measured entrainment forces indicate particle loosening by spawning lowered grain resistance to motion by 12–37% on average compared to unspawned beds. In addition, for the same discharges, boundary shear stress was 13–41% higher on a redd due to flow convergence on the tailspill. Visual measurements of particle entrainment further indicated redd instability, as bed‐average shear stress was 22% lower at incipient motion and 29% lower at the discharge that mobilized all grain sizes on a redd. Overall, results demonstrate that redds are unstable compared to unspawned beds, which increases the risk of scour for buried eggs but may facilitate fine sediment flushing and improve the quality of spawning gravels for future generations of spawners. Therefore, managing salmon returns to increase streambed disturbance may be an effective tool for reducing sedimentation impacts on salmon reproduction.
On the use of rhodamine WT for the characterization of stream hydrodynamics and transient storage
Authors: Runkel Robert L.
Published: July 2015

Recent advances in fluorometry have led to increased use of rhodamine WT as a tracer in streams and rivers. In light of this increased use, a review of the dye's behavior in freshwater systems is presented. Studies in the groundwater literature indicate that rhodamine WT is transported nonconservatively, with sorption removing substantial amounts of tracer mass. Column studies document a two‐step breakthrough curve in which two structural isomers are chromatographically separated. Although the potential for nonconservative transport is acknowledged in the surface water literature, many studies assume that sorptive losses will not affect the characterization of physical transport processes. A literature review and modeling analysis indicates that this assumption is valid for quantification of physical properties that are based on the bulk of the tracer mass (traveltime), and invalid for the characterization of processes represented by the tracer tail (transient storage attributable to hyporheic exchange). Rhodamine WT should be considered nonconservative in the hyporheic zone due to nonconservative behavior demonstrated for similar conditions in groundwater. As such, rhodamine WT should not be used as a quantitative tracer in hyporheic zone investigations, including the study of long flow paths and the development of models describing hyporheic zone processes. Rhodamine WT may be used to qualitatively characterize storage in large systems, where there are few practical alternatives. Qualitative investigations should rely on early portions of the tracer profile, making use of the temporal resolution afforded by in situ fluorometry, while discarding later parts of the tracer profile that are adversely affected by sorption.
Interdependence of chronic hydraulic dysfunction and canopy processes can improve integrated models of tree response to drought
Authors: Mackay D. Scott , Roberts David E. , Ewers Brent E. , Sperry John S. , McDowell Nathan G. , Pockman William T.
Published: July 2015

Hydraulic systems of plants have evolved in the context of carbon allocation and fitness trade‐offs of maximizing carbon gain and water transport in the face of short and long‐term fluctuations in environmental conditions. The resulting diversity of traits include a continuum of isohydry‐anisohydry or high to low relative stomatal closure during drought, shedding of canopy foliage or disconnecting roots from soil to survive drought, and adjusting root areas to efficiently manage canopy water costs associated with photosynthesis. These traits are examined within TREES, an integrated model that explicitly couples photosynthesis and carbon allocation to soil‐plant hydraulics and canopy processes. Key advances of the model are its ability to account for differences in soil and xylem cavitation, transience of hydraulic impairment associated with delayed or no refilling of xylem, and carbon allocation to plant structures based on photosynthetic uptake of carbon and hydraulic limitations to water transport. The model was used to examine hydraulic traits of cooccurring isohydric (piñon pine) and anisohydric (one‐seed juniper) trees from a field‐based experimental drought. Model predictions of both transpiration and leaf water potential were improved when there was no refilling of xylem over simulations where xylem was able refill in response to soil water recharge. Model experiments with alternative root‐to‐leaf area ratios (RR/L) showed the RR/L that supports maximum cumulative water use is not beneficial for supporting maximum carbon gain during extended drought, illustrating how a process model reveals trade‐offs in plant traits.
Persistent questions of heterogeneity, uncertainty, and scale in subsurface flow and transport
Authors: Kitanidis Peter K.
Published: July 2015

When Water Resources Research was launched in 1965, heterogeneity, uncertainty, and scale issues in subsurface hydrology were in the backburner. Only about 10 years later, under the stimulus of dealing with solute transport problems, these problems received attention. The stochastic approach brought tools to deal both with problems of upscaling, also known as homogenization and coarse‐graining, and uncertainty quantification. Effective conductivity and effective dispersion, also known as macrodispersion, coefficients in statistically homogeneous formations were extensively studied. Mixing, in its role of affecting reaction rates, started receiving attention. While in the dispersion problem emphasis was on Fickian representations, more sophisticated models have also been studied. Uncertainty quantification in the inverse problem has also made progress and geostatistical ideas, as well as ideas originating in signal processing, influenced how we approach problems of inference like interpolation and inverse modeling. My view is that we should emphasize information aspects, i.e., the collection of more and better data, their correct assimilation, the quantification of uncertainty associated with predictions, and the selection of designs or policies that accurately reflect what we actually know and thus manage risk. Progress in this department has been hampered by ingrained ideas, inadequate training, and inadequate resources. Research in problems of upscaling will continue to shed new light and provide better tools to deal with onerous problems. At the same time, no cure is more universally potent than using a more refined grid. Finally, although research is active, the diffusion of research results to education and practice has been slow.
A dangerous boomerang: Injunctive norms, hostile sexist attitudes, and male‐to‐female sexual aggression
Authors: Bosson Jennifer K. , Parrott Dominic J. , Swan Suzanne C. , Kuchynka Sophie L. , Schramm Andrew T.
Published: July 2015

This study examined the interactive effects of injunctive norm exposure and hostile and benevolent sexist attitudes on men's sexually aggressive responses during a behavioral analogue paradigm in which they interacted online with a bogus female partner. Heterosexual adult men (n = 201), recruited from an online sample, read fictional information regarding other men's approval of misogynistic, paternalistic, or egalitarian treatment of women, or non‐gender‐relevant control information. Through a media preference survey, men then learned that their female partner disliked sexual content in films, after which they had an opportunity to send her up to 120 sec' worth of either a sexually explicit or nonsexual film clip. Validating the online sexual aggression paradigm, men with a 1‐year history of sexual assault exhibited more sexually aggressive responding during the film selection paradigm. Moreover, exposure to injunctive norm information produced a boomerang effect, such that men high in hostile sexist attitudes showed an increase in sexual aggression when confronted with paternalism and gender equality norms. Conversely, exposure to paternalism and gender equality norms suppressed the otherwise protective function of high benevolent sexism in reducing men's sexually aggressive tendencies. The implications of these results for social norms interventions are discussed. Aggr. Behav. 41:580–593, 2015. © 2015 Wiley Periodicals, Inc.
Does the Narrative Style of Video Evidence Influence Judgements About Rape Complainant Testimony?
Authors: Westera Nina J. , McKimmie Blake M. , Kebbell Mark R. , Milne Rebecca , Masser Barbara
Published: July 2015

Four studies investigated lawyers' concerns that the narrative style of police interviews with adult rape complainants reduces the impact of this interview as video evidence. Study 1 (N = 96) compared mock juror perceptions of simulated evidence‐in‐chief either in traditional short‐answer or narrative style and found testimony style was not a predictor of complainant credibility. Studies 2 (N = 104), 3 (N = 102) and 4 (N = 102) examined different variables that change with testimony style—the number of questions asked, overall testimony length and response length. The number of questions asked was the only predictor of complainant credibility; more questions resulted in higher credibility ratings. These findings suggest that lawyers' concerns about narrative style interviewing are unwarranted. Copyright © 2015 John Wiley & Sons, Ltd.
Effect of Carbon/Carbon Preform Density on the Microstructure and Properties of Mo2C Interlayer‐Modified Carbon/Carbon–Copper Composites for Sliding Contact Materials
Authors: Zhou Wen Yan , Ran Li Ping , Peng Ke , Ge Yi Cheng , Wu Huang , Yi Mao Zhong
Published: July 2015

Carbon/carbon–copper(C/C‐Cu) composites were fabricated by pressure‐less infiltration of Cu into carbon/carbon (C/C) preforms modified with Mo2C interlayer by a molten salt method. Cu filled the pores inside the Mo2C‐modified preforms fully, and retained an interconnected net‐like distribution in the C/C‐Cu composites. The electrical resistivity and flexural strength increased, whereas impact toughness decreased with the increase of preform density. Fiber pull‐out and crack propagation along the interface contributed to the pseudo‐plastic behavior of the composites. The tribological performance was improved with the increase of preform density due to the better lubrication of transfer films.
Recent Advances in Processing and Application of Nanostructured Titanium for Dental Implants
Authors: Polyakov Alexander V. , Dluhoš Ludĕk , Dyakonov Grigory S. , Raab Georgy I. , Valiev Ruslan Z.
Published: July 2015

The paper presents the results of developments of nanostructured Ti with enhanced strength in the form of long‐length rods. Using the technique of ECAP‐Conform and drawing, rods with record strength properties were obtained, with UTS 1 330 MPa and endurance limit based on 107 cycles of 620 MPa. The developed processing route is quite effective and can be implemented at the commercial scale. It is shown that the use of nano‐Ti rods allows for creation of dental implants with improved design and a smaller diameter. Such modern miniature implants with the diameter of 2.4 and 2 mm were manufactured by the “Timplant” company and the results of successful clinical trials are presented.
Al–RE Intermetallic Phase Stability and Effects on Corrosion Behavior in Cold‐Chamber HPDC AE44 Alloy
Authors: Jiao Yufeng , Zhang Jinghuai , He Lili , Zhang Milin , Jiang Fengchun , Wang Wei , Han Liming , Xu Longjiang , Wu Ruizhi
Published: July 2015

Mg–4Al–4RE (wt%, AE44) alloy is prepared by cold‐chamber high‐pressure die‐casting (HPDC). The microstructure, thermal stability of Al–RE phases and its effect on corrosion behavior are investigated. The main strengthening phase is Al11RE3, which is thermally instable when heated at 400 °C. Some Al11RE3 would be transformed to Al2RE. The alloy in HPDC state exhibits relatively high corrosion resistance due to the Al11RE3 at grain boundaries that can act as the corrosion barrier. While after heat treatment at 400 °C for 1000 h and 5000 h, the corrosion resistance performance degrades due to the changes of morphology and distribution of Al–RE phases.
Influence of Heat Treatment Temperature on Corrosion Characteristics of Biodegradable EW10X04 Mg Alloy Coated with Nd
Authors: Katarivas Levy Galit , Aghion Eli
Published: July 2015

The effect of heat treatment temperature (150, 350, and 550 °C) on corrosion of biodegradable EW10X04 Mg alloy coated with Nd was tested in PBS solution. The microstructure was examined by SEM, XRD, and XPS analysis and corrosion resistancewas evaluated by immersion test,potentiodynamic polarization and EIS analysis. Comparatively the complex microstructure of the surface obtained after heat treatment at 350 °C has the best corrosion resistance. This was mainly due to the formation of a nearly continuous network of Mg41Nd5 that acts as a protective barrier around α‐Mg grains. The heat treatment at 150 °C was not effective in creating a similar protective network. In the heat treatment at 550 °C, a new intermetallic phase (Mg3Nd)was formed having a detrimental effect on corrosion resistance.
Two‐Dimensional Transition Metal Dichalcogenides in Biosystems
Authors: Kalantar‐zadeh Kourosh , Ou Jian Zhen , Daeneke Torben , Strano Michael S. , Pumera Martin , Gras Sally L.
Published: July 2015

The intriguing properties of two‐dimensional transition metal dichalcogenides (2D TMDCs) have led to a significant body of fundamental research and rapid uptake of these materials in many applications. Specifically, 2D TMDCs have shown great potential in biological systems due to their tunable electronic characteristics, unique optical properties, stability in aqueous environments, large surface area that can be manipulated and functionalized as well as an intercalatable layered structure, and low levels of toxicity. Here, the characteristics and use of 2D TMDCs for biological applications are reviewed and future possibilities for these materials in biological systems are outlined.
Epitaxy on Demand
Authors: Nijland Maarten , Thomas Sean , Smithers Mark A. , Banerjee Nirupam , Blank Dave H. A. , Rijnders Guus , Xia Jing , Koster Gertjan , ten Elshof Johan E.
Published: July 2015

Perovskite oxide heteroepitaxy is realized on the top of inorganic nanosheets that are covering the amorphous oxide surfaces of Si substrates. Utilizing pulsed laser deposition, thin films of SrRuO3 in a (001)pc and (110)pc orientation on nanosheets of Ca2Nb3O10 and Ti0.87O2 are grown, respectively. The two types of nanosheets are patterned to locally tailor the crystallographic orientation and properties of SrRuO3. The success of our approach is demonstrated by electron backscatter diffraction and spatial magnetization maps. An unprecedented control of perovskite film growth on arbitrary substrates is illustrated in this work, and the methods that are developed to deposit SrRuO3 thin films are a viable starting point for growth of artificial heteroepitaxial thin films that require a bottom electrode. Control is not just reached in the direction of film growth, as the crystal orientation and film properties are regulated laterally on the surface of micropatterned nanosheets. Local control of magnetic properties is illustrated, which holds out prospects for the fabrication of next‐generation devices like noncollinear magnetic random access memories.
Core–Shell Nanoparticles: Characterizing Multifunctional Materials beyond Imaging—Distinguishing and Quantifying Perfect and Broken Shells
Authors: Tschulik Kristina , Ngamchuea Kamonwad , Ziegler Christoph , Beier Max Gregor , Damm Christine , Eychmueller Alexander , Compton Richard G.
Published: July 2015

Core–shell nanoparticles (NPs) are amongst the most promising candidates in the development of new functional materials. Their fabrication and characterization are challenging, in particular when thin and intact shells are needed. To date no technique has been available that differentiates between intact and broken or cracked shells. Here a method is presented to distinguish and quantify these types of shells in a single cyclic voltammetry experiment by using the different electrochemical reactivities of the core and the shell material. A simple comparison of the charge measured during the stripping of the core material before and after the removal of the shell makes it possible to determine the quality of the shells and to estimate their thickness. As a proof‐of‐concept two multifunctional examples of core–shell NPs, Fe3O4@Au and Au@SnO2, are used. This general and original method can be applied whenever core and shell materials show different redox properties. Because billions of NPs are probed simultaneously and at a low cost, this method is a convenient new screening tool for the development of new multifunctional core–shell materials and is hence a powerful complementary technique or even an alternative to the state‐of‐the‐art characterization of core–shell NPs by TEM.
Bioinspired Blood Compatible Surface Having Combined Fibrinolytic and Vascular Endothelium‐Like Properties via a Sequential Coimmobilization Strategy
Authors: Zhan Wenjun , Shi Xiujuan , Yu Qian , Lyu Zhonglin , Cao Limin , Du Hui , Liu Qi , Wang Xin , Chen Gaojian , Li Dan , Brash John L. , Chen Hong
Published: July 2015

Developing surfaces with antithrombotic properties is of great interest for the applications of blood‐contacting biomaterials and medical devices. It is promising to coimmobilize two or more biomolecules with different and complementary functions to improve blood compatibility. However, the general one‐pot strategy usually adopted by previous studies suffers the problems of inevitable competition between diverse biomolecules and uncontrollability of the relative quantities of the immobilized biomolecules. To solve these problems, a new sequential coimmobilization strategy is proposed and applied to fabricate a blood compatible surface. Polyurethane surface is modified with a copolymer, poly(2‐hydroxyethyl methacrylate‐co‐1‐adamantan‐1‐ylmethyl methacrylate), which serves as a linker‐spacer for sequential attachment of two functional molecules, a hexapeptide containing REDV (Arg‐Glu‐Asp‐Val) sequence, and a modified cyclodextrin bearing 7 lysine ligands, through covalent bonding and host–guest interaction, respectively. The resulting surface combines the antithrombogenic properties of the vascular endothelium and the clot lysing properties of the fibrinolytic system. Importantly, neither of the two functions of REDV peptide and lysine is compromised by the presence of the other, suggesting the enhanced blood compatibility. These results suggest a new strategy to engineer multifunctional surfaces by coimmobilization of bioactive molecules having unique functionalities.