bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetospheric ion influence on magnetic reconnection at the duskside magnetopause
Authors: Fuselier S. A. , Burch J. L. , Cassak P. A. , Goldstein J. , Gomez R. G. , Goodrich K. , Lewis W. S. , Malaspina D. , Mukherjee J. , Nakamura R. , Petrinec S. M. , Russell C. T. , Strangeway R. J. , Torbert R. B. , Trattner K. J. , Valek P. 
Published: February 2016

AbstractMagnetospheric ions from the ring current, warm plasma cloak, and the plasmaspheric drainage plume all interact with the dusk flank magnetopause. During periods of strong magnetospheric convection, these ions may contribute significantly to the magnetospheric mass density at the magnetopause. Observations from the Magnetospheric Multiscale mission Hot Plasma Composition Analyzer at the duskside magnetopause near reconnection X lines show that ions from the ring current and warm plasma cloak may have high mass densities. However, these mass densities are not as large as the mass density in the magnetosheath. The results suggest that except for possible influence from the plasmaspheric drainage plume, the other major magnetospheric ion populations do not greatly influence asymmetric reconnection at the duskside magnetopause.
Disturbance zonal and vertical plasma drifts in the Peruvian sector during solar minimum phases
Authors: Santos A. M. , Abdu M. A. , Souza J. R. , Sobral J. H. A. , Batista I. S. 
Published: February 2016

AbstractIn the present work, we investigate the behavior of the equatorial F region zonal plasma drifts over the Peruvian region under magnetically disturbed conditions during two solar minimum epochs, one of them being the recent prolonged solar activity minimum. The study utilizes the vertical and zonal components of the plasma drifts measured by the Jicamarca (11.95°S; 76.87°W) incoherent scatter radar during two events that occurred on 10 April 1997 and 24 June 2008 and model calculation of the zonal drift in a realistic ionosphere simulated by the Sheffield University Plasmasphere‐Ionosphere Model‐INPE. Two main points are focused: (1) the connection between electric fields and plasma drifts under prompt penetration electric field during a disturbed periods and (2) anomalous behavior of daytime zonal drift in the absence of any magnetic storm. A perfect anticorrelation between vertical and zonal drifts was observed during the night and in the initial and growth phases of the magnetic storm. For the first time, based on a realistic low‐latitude ionosphere, we will show, on a detailed quantitative basis, that this anticorrelation is driven mainly by a vertical Hall electric field induced by the primary zonal electric field in the presence of an enhanced nighttime E region ionization. It is shown that an increase in the field line‐integrated Hall‐to‐Pedersen conductivity ratio
, which can arise from precipitation of energetic particles in the region of the South American Magnetic Anomaly, is capable of explaining the observed anticorrelation between the vertical and zonal plasma drifts. Evidence for the particle ionization is provided from the occurrence of anomalous sporadic E layers over the low‐latitude station, Cachoeira Paulista (22.67°S; 44.9°W)—Brazil. It will also be shown that the zonal plasma drift reversal to eastward in the afternoon two hours earlier than its reference quiet time pattern is possibly caused by weakening of the zonal wind system during the prolonged solar minimum period.
Data assimilation of surface displacements to improve geomechanical parameters of gas storage reservoirs
Authors: Zoccarato C. , Baù D. , Ferronato M. , Gambolati G. , Alzraiee A. , Teatini P. 
Published: February 2016

AbstractAlthough the beginning of reservoir geomechanics dates back to the late 1960s, only recently stochastical geomechanical modelling has been introduced into the general framework of reservoir operational planning. In this study, the ensemble smoother (ES) algorithm, i.e., an ensemble‐based data assimilation method, is employed to reduce the uncertainty of the constitutive parameters characterizing the geomechanical model of an underground gas storage (UGS) field situated in the upper Adriatic sedimentary basin (Italy), the Lombardia UGS. The model is based on a nonlinear transversely isotropic stress‐strain constitutive law and is solved by 3‐D finite elements. The Lombardia UGS experiences seasonal pore pressure change caused by fluid extraction/injection leading to land settlement/upheaval. The available observations consist of vertical and horizontal time‐lapse displacements accurately measured by persistent scatterer interferometry (PSI) on RADARSAT scenes acquired between 2003 and 2008. The positive outcome of preliminary tests on simplified cases has supported the use of the ES to jointly assimilate vertical and horizontal displacements. The ES approach is shown to effectively reduce the spread of the uncertain parameters, i.e., the Poisson's ratio, the ratio between the horizontal and vertical Young and shear moduli, and the ratio between the virgin loading (I cycle) and unloading/reloading (II cycle) compressibility. The outcomes of the numerical simulations point out that the updated parameters depend on the assimilated measurement locations as well as the error associated to the PSI measurements. The parameter estimation may be improved by taking into account possible model and/or observation biases along with the use of an assimilation approach, e.g., the Iterative ensemble smoother, more appropriate for nonlinear problems.
The crust‐mantle interaction in continental subduction channels: Zircon evidence from orogenic peridotite in the Sulu orogen
Authors: Li Hai‐Yong , Chen Ren‐Xu , Zheng Yong‐Fei , Hu Zhaochu 
Published: February 2016

AbstractA combined secondary ion mass spectrometer and laser ablation‐(multicollector)‐inductively coupled plasma mass spectrometer study of zircon U‐Pb ages, trace elements, and O and Hf isotopes was carried out for orogenic peridotite and its host gneiss in the Sulu orogen. Newly grown zircon domains exhibit weak zoning or no zoning, relatively low Th/U ratios (<0.1), low heavy rare earth element (HREE) contents, steep middle rare earth element‐HREE patterns, negative Eu anomalies, and negative to low δ18O values of −11.3 to 0.9‰ and U‐Pb ages of 220 ± 2 to 231 ± 4 Ma. Thus, these zircons would have grown from metasomatic fluids during the early exhumation of deeply subducted continental crust. The infiltration of metasomatic fluids into the peridotite is also indicated by the occurrence of hydrous minerals such as amphibole, serpentine, and chlorite. In contrast, relict zircon domains exhibit magmatic zircon characteristics. Their U‐Pb ages and trace element and Hf‐O isotope compositions are similar to those for protolith zircons from ultrahigh‐pressure metamorphic rocks in the Dabie‐Sulu orogenic belt. Thus, these relict magmatic zircons would be physically transported into the peridotite by metasomatic fluids originated from the deeply subducted continental crust. Therefore, the peridotite underwent metasomatism by aqueous solutions derived from dehydration of the deeply subducted continental crust during the early exhumation. It is these crustally derived fluids that would have brought not only such chemical components as Zr and Si but also tiny zircon grains from the deeply subducted crustal rocks into the peridotite at the slab‐mantle interface in continental subduction channels. As such, the orogenic peridotite records the crust‐mantle interaction at the deep continental subduction zone.
Influence of fortnightly tides on earthquake triggering at the East Pacific Rise at 9°50′N
Authors: Bhatnagar Tarini , Tolstoy Maya , Waldhauser Felix 
Published: February 2016

AbstractThe study of tidal forcing provides an opportunity to view the response of the solid Earth to known changes in stress. Earthquakes triggered by diurnal and semidiurnal tidal forces have been well documented for the deep ocean and some terrestrial environments. However, few studies examine the influence of fortnightly tides on earthquake triggering and only in terrestrial environments. We assess triggering of microearthquakes related to true fortnightly tides and fortnightly tidal modulations along the East Pacific Rise at 9°50′N, where strong diurnal and semidiurnal triggering of earthquakes has been observed. An ocean bottom seismograph experiment collected microearthquake data between October 2003 and January 2007, a time period that included a well‐documented submarine eruption culminating in January 2006. We examine how triggering changed through the build up to and aftermath of this seafloor‐spreading event. Results show that earthquakes occur preferentially during times of increasing peak volumetric stress leading up to the eruption, with strong statistical significance (Schuster Test p values up to 2.22e−31). However, the correlation loses its strength immediately prior to and during the eruptive period (p value as high as 0.2837), when competing tectonic and magmatic stresses may occur. Post‐eruption triggering reappears (p value 1.45e−26) but with opposite phase. Statistical significance is also explored using Monte Carlo method, highlighting limitations of swarm‐dominated time series for the Schuster Test. Nevertheless, the observations are consistent with a shift in the dominating stress triggering the earthquakes from extensional tectonics to magmatic processes, followed by a post‐eruption period of cooling, relaxation, and possibly magma chamber refilling.
Changing characteristics of extreme wet and dry spells of Indian monsoon rainfall
Authors: Vinnarasi R. , Dhanya C. T. 
Published: February 2016

AbstractModeling of extreme events and its dynamic behavior have always been an intriguing topic. Increase in the magnitude and frequency of extreme events has widely been reported in recent decades, which is attributed to abrupt changes in climate. Numerous studies on extreme Indian monsoon characteristics, using a coarse‐resolution data set, have pointed out significant changes in heavy precipitation pattern over India. However, these studies differ in their conclusions, emphasizing the need for a fine‐resolution analysis. The present study aims to analyze the spatiotemporal variations and trends in the extreme (wet and dry) Indian monsoon precipitation, using 0.25° × 0.25° high‐resolution gridded data for a period of 113 years (1901–2013). Significant increase in the maximum intensity of rainfall and spatial heterogeneity is observed over the past half century. In addition, significant negative trends in wet spell durations and positive trends in dry spell durations are observed over wet regions; whereas contrasting trends are observed over dry regions. A shift in the frequency distribution of extreme events during the monsoon period is also noticed. The 50 year return level of maximum intensity clearly shows positive trends over the past century. Though characteristics of extremes are observed to be highly localized, apparent signs of wet regions turning drier and dry regions turning wetter are obtained. A comprehensive insight into different characteristics (intensity, spell, onset, and frequency) of Indian monsoon extremes is provided, which will help in effective water resources management and flood/drought hazard preparedness.
Radiative effects of global MODIS cloud regimes
Authors: Oreopoulos Lazaros , Cho Nayeong , Lee Dongmin , Kato Seiji 
Published: February 2016

AbstractWe update previously published Moderate Resolution Imaging Spectroradiometer (MODIS) global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 data set. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux data sets. Our results clearly show that the CRs are radiatively distinct in terms of shortwave, longwave, and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles, to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance data sets suffering from imperfect spatiotemporal matching depend on CR and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations.
Numerical modeling of subaqueous sand dune morphodynamics
Authors: Doré Arnaud , Bonneton Philippe , Marieu Vincent , Garlan Thierry 
Published: February 2016

AbstractThe morphodynamic evolution of subaqueous sand dunes is investigated, using a 2‐D Reynolds‐averaged Navier‐Stokes numerical model. A laboratory experiment where dunes are generated under stationary unidirectional flow conditions is used as a reference case. The model reproduces the evolution of the erodible bed until a state of equilibrium is reached. In particular, the simulation exhibits the different stages of the bed evolution, e.g., the incipient ripple generation, the nonlinear bed form growing phase, and the dune field equilibrium phase. The results show good agreement in terms of dune geometrical dimensions and time to equilibrium. After the emergence of the first ripple field, the bed growth is driven by cascading merging sequences between bed forms of different heights. A sequence extracted from the simulation shows how the downstream bed form is first eroded before merging with the upstream bed form. Superimposed bed forms emerge on the dune stoss sides during the simulation. An analysis of the results shows that they emerge downstream of a slight deflection on the dune profile. The deflection arises due to a modification of the sediment flux gradient consecutive to a reduction in the turbulence relaxation length while the upstream bed form height decreases. As they migrate, superimposed bed forms grow on the dune stoss side and eventually provoke the degeneration of the dune crest. Cascading merging sequences and superimposed bed forms dynamics both influence the dune field evolution and size and therefore play a fundamental role in the dune field self‐organization process.
The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U‐Th‐Sm)/He thermochronology
Authors: Wildman Mark , Brown Roderick , Beucher Romain , Persano Cristina , Stuart Fin , Gallagher Kerry , Schwanethal James , Carter Andrew 
Published: February 2016

AbstractAtlantic‐type continental margins have long been considered “passive” tectonic settings throughout the entire postrift phase. Recent studies question the long‐term stability of these margins and have shown that postrift uplift and reactivation of preexisting structures may be a common feature of a continental margin's evolution. The Namaqualand sector of the western continental margin of South Africa is characterized by a ubiquitously faulted basement but lacks preservation of younger geological strata to constrain postrift tectonic fault activity. Here we present the first systematic study using joint apatite fission track and apatite (U‐Th‐Sm)/He thermochronology to achieve a better understanding on the chronology and tectonic style of landscape evolution across this region. Apatite fission track ages range from 58.3 ± 2.6 to 132.2 ± 3.6 Ma, with mean track lengths between 10.9 ± 0.19 and 14.35 ± 0.22 µm, and mean (U‐Th‐Sm)/He sample ages range from 55.8 ± 31.3 to 120.6 ± 31.4 Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150–130 Ma and 110–90 Ma with limited cooling during the Cenozoic. Estimates of denudation based on these thermal histories predict approximately 1–3 km of denudation coinciding with two major tectonic events. The first event, during the Early Cretaceous, was driven by continental rifting and the development and removal of synrift topography. The second event, during the Late Cretaceous, includes localized reactivation of basement structures as well as regional mantle‐driven uplift. Relative tectonic stability prevailed during the Cenozoic, and regional denudation over this time is constrained to be less than 1 km.
From ocean depths to mountain tops: Uplift of the Troodos ophiolite (Cyprus) constrained by low‐temperature thermochronology and geomorphic analysis
Authors: Morag Navot , Haviv Itai , Katzir Yaron 
Published: February 2016

AbstractThe timing and mode of uplift of the Troodos ophiolite are constrained by low‐temperature thermochronology combined with geomorphic analysis. Zircon (U‐Th)/He and apatite fission track cooling ages in the Troodos plutonic sequence are all Cretaceous (83–106 Ma) and within error of published zircon U‐Pb crystallization ages. This indicates early cooling of the oceanic crust and termination of spreading axis magmatism at ~90 Ma. Apatite (U‐Th)/He ages decrease with reconstructed crustal depths from ~40 Ma near the top of the sheeted‐dike complex to ~4 Ma within the mantle sequence. A prominent inflection point in the age versus depth curve defines the bottom of the exhumed helium partial retention zone and records the onset of rapid exhumation of the main Troodos massif at 6 ± 2 Ma. Inverse thermal modeling supports this conclusion, indicating that the timing of uplift is earlier than previously estimated. The boundaries of the mantle sequence exposed in the core of the Troodos structure closely overlap the boundaries of a concentric zone delineated by high local relief and higher channel steepness indices, indicating differential exhumation and uplift of this area relative to its surroundings. This zone also overlaps with a prominent negative Bouguer gravity anomaly. The timing and pattern of the Troodos ophiolite uplift suggest that it is driven by serpentinite diapirism, possibly triggered by Miocene reactivation of subduction along the Cyprean Arc. The worldwide ubiquity of suprasubduction zone ophiolites may thus reflect the importance of extensive serpentinization at the overthrusting mantle wedge in obduction processes.
Characterization of reciprocity gaps from interference tests in fractured media through a dual porosity model
Authors: Sanchez‐Vila X. , Ackerer P. , Delay F. , Guadagnini A. 
Published: February 2016

AbstractWe analyze drawdown reciprocity gaps emerging in interference tests performed in a confined fissured karstic formation. Modeling the system as a dual porosity continuum allows characterizing the dynamics of the relative contribution of the connected fractures and the rock matrix to the total flow rate extracted at the pumping wells. Observed lack of reciprocity of drawdowns can then be linked to the occurrence of processes that are not accounted for in the classical flow models based on a single‐continuum representation of the system through flow equations grounded on Darcy's law only. We show that interpreting the system as a dual porosity continuum can cause drawdown reciprocity gaps to emerge as a consequence of local effects associated with an identifiable contribution of the matrix to the total fluid extracted at the well location during pumping. These theoretical results are then employed to identify the contribution to the flow being supplied to the pumping well by the low conductivity matrix constituting the host rock formation, in contrast to that provided by the fractures. An application to data from two interference tests performed at the Hydrogeological Experimental Site (HES) in Poitiers, France, illustrates the approach. We show that, whenever the matrix is assumed to provide a contribution to the total flow rate extracted, nonreciprocity is expected, the latter being linked to the occurrence of a differential drawdown between fracture and matrix at the pumping well. This difference decreases with time in the example presented, displaying a power law late time behavior, with nonreciprocity effects persisting up to remarkably long times.
Future changes to the Indonesian Throughflow and Pacific circulation: The differing role of wind and deep circulation changes
Authors: Sen Gupta Alex , McGregor Shayne , van Sebille Erik , Ganachaud Alexandre , Brown Jaclyn N. , Santoso Agus 
Published: February 2016

AbstractClimate models consistently project a substantial decrease in the Indonesian Throughflow (ITF) in response to enhanced greenhouse warming. On interannual timescales ITF changes are largely related to tropical Pacific wind variability. However, on the multidecadal timescales investigated here we demonstrate that regional winds and associated changes in the upper ocean circulation cannot explain the projected ITF decrease. Instead, the decrease is related to a weakening in the northward flow of deep waters entering the Pacific basin at ~40°S and an associated reduction in the net basin‐wide upwelling to the north of the southern tip of Australia. This can be traced back to consistent changes in the Antarctic Circumpolar Current and Southern Ocean overturning, although questions still remain as to the ultimate drivers. In contrast to the ITF decrease, substantial projected changes to the upper ocean circulation of the Pacific basin are well explained by robust changes in the surface winds.
Does Renin‐Angiotensin System Blockade Protect Lupus Nephritis Patients From Atherosclerotic Cardiovascular Events? A Case–Control Study
Authors: Tselios Konstantinos , Gladman Dafna D. , Su Jiandong , Urowitz Murray B. 
Published: February 2016

ObjectiveAngiotensin‐converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are used as an adjuvant treatment in lupus nephritis (LN) patients with proteinuria. The primary aim of this study was to discover whether ACE inhibitors/ARBs have an atheroprotective effect similar to other, at‐risk, populations.MethodsA total of 144 patients (cases; mean ± SD age at onset 34 ± 12.1 years, followup 14.9 ± 8.6 years) with LN who were treated with ACE inhibitors/ARBs for at least 5 years were enrolled. The control group comprised 301 LN patients (mean ± SD age at onset 34.1 ± 13.2 years, followup 13.4 ± 7.9 years) with no such treatment. All patients were followed for the occurrence of atherosclerotic cardiovascular events (CVEs), consisting of transient ischemic attack and stroke, angina, myocardial infarction, percutaneous transluminal coronary angioplasty (PTCA), coronary artery bypass graft (CABG), and congestive heart failure. Patients with preexisting CVEs were excluded.ResultsThere were no significant differences in the cumulative occurrence of CVEs (9.7% for treated versus 8.6% for nontreated patients; P = 0.708); however, hard events (stroke, myocardial infarction, CABG, and PTCA) were less frequent in treated patients (4.17% versus 5.32%). Cases were more frequently hypertensive (100% versus 52.8%; P < 0.001) and diabetic (10.4% versus 4.7%; P = 0.021), whereas controls more frequently had hypercholesterolemia (27.9% versus 18.1%; P = 0.024) and elevated triglycerides (14% versus 4.9%; P = 0.004); other variables did not differ significantly. Regression analysis failed to confirm ACE inhibitor/ARB nonuse as an important predictor of future CVEs.ConclusionOur data do not support the hypothesis that ACE inhibitors/ARBs may be protective against atherosclerotic CVEs in LN patients.
Nickel‐Catalyzed α‐Benzylation of Arylacetonitriles via CO Activation
Authors: Xiao Jing , Yang Jia , Chen Tieqiao , Han Li‐Biao 
Published: February 2016

AbstractEfficient Ni‐catalyzed direct cross‐couplings of benzylic alcohol derivatives with arylacetonitriles via CO activation are described. Various α‐benzylated arylacetonitriles including those with functional groups can be prepared under mild reaction conditions.magnified image