bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress changes, focal mechanisms, and earthquake scaling laws for the 2000 dike at Miyakejima (Japan)
Authors: Passarelli Luigi , Rivalta Eleonora , Cesca Simone , Aoki Yosuke 
Published: May 2015

AbstractFaulting processes in volcanic areas result from a complex interaction of pressurized fluid‐filled cracks and conduits with the host rock and local and regional tectonic setting. Often, volcanic seismicity is difficult to decipher in terms of the physical processes involved, and there is a need for models relating the mechanics of volcanic sources to observations. Here we use focal mechanism data of the energetic swarm induced by the 2000 dike intrusion at Miyakejima (Izu Archipelago, Japan), to study the relation between the 3‐D dike‐induced stresses and the characteristics of the seismicity. We perform a clustering analysis on the focal mechanism (FM) solutions and relate them to the dike stress field and to the scaling relationships of the earthquakes. We find that the strike and rake angles of the FMs are strongly correlated and cluster on bands in a strike‐rake plot. We suggest that this is consistent with optimally oriented faults according to the expected pattern of Coulomb stress changes. We calculate the frequency‐size distribution of the clustered sets finding that focal mechanisms with a large strike‐slip component are consistent with the Gutenberg‐Richter relation with abvalue of about 1. Conversely, events with large normal faulting components deviate from the Gutenberg‐Richter distribution with a marked roll‐off on its right‐hand tail, suggesting a lack of large‐magnitude events (Mw > 5.5). This may result from the interplay of the limited thickness and lower rock strength of the layer of rock above the dike, where normal faulting is expected, and lower stress levels linked to the faulting style and low confining pressure.
Revisiting borehole strain, typhoons, and slow earthquakes using quantitative estimates of precipitation‐induced strain changes
Authors: Hsu Ya‐Ju , Chang Yuan‐Shu , Liu Chi‐Ching , Lee Hsin‐Ming , Linde Alan T. , Sacks Selwyn I. , Kitagawa Genshio , Chen Yue‐Gau 
Published: May 2015

AbstractTaiwan experiences high deformation rates, particularly along its eastern margin where a shortening rate of about 30 mm/yr is experienced in the Longitudinal Valley and the Coastal Range. Four Sacks‐Evertson borehole strainmeters have been installed in this area since 2003. Liu et al. (2009) proposed that a number of strain transient events, primarily coincident with low‐barometric pressure during passages of typhoons, were due to deep‐triggered slow slip. Here we extend that investigation with a quantitative analysis of the strain responses to precipitation as well as barometric pressure and the Earth tides in order to isolate tectonic source effects. Estimates of the strain responses to barometric pressure and groundwater level changes for the different stations vary over the ranges −1 to −3 nanostrain/millibar(hPa) and −0.3 to −1.0 nanostrain/hPa, respectively, consistent with theoretical values derived using Hooke's law. Liu et al. (2009) noted that during some typhoons, including at least one with very heavy rainfall, the observed strain changes were consistent with only barometric forcing. By considering a more extensive data set, we now find that the strain response to rainfall is about −5.1 nanostrain/hPa. A larger strain response to rainfall compared to that to air pressure and water level may be associated with an additional strain from fluid pressure changes that take place due to infiltration of precipitation. Using a state‐space model, we remove the strain response to rainfall, in addition to those due to air pressure changes and the Earth tides, and investigate whether corrected strain changes are related to environmental disturbances or tectonic‐original motions. The majority of strain changes attributed to slow earthquakes seem rather to be associated with environmental factors. However, some events show remaining strain changes after all corrections. These events include strain polarity changes during passages of typhoons (a characteristic that is not anticipated from our estimates of the precipitation transfer function) that are more readily explained in terms of tectonic‐origin motions, but clearly the triggering argument is now weaker than that presented in Liu et al. (2009). Additional on‐site water level sensors and rain gauges will provide data critical for a more complete understanding, including the currently unresolved issue of why, for some typhoons, there appears to be a much smaller transfer function for precipitation‐induced strain changes.
Real‐time estimation of Arctic sea ice thickness through maximum covariance analysis
Authors: Dirkson Arlan , Merryfield William J. , Monahan Adam 
Published: May 2015

AbstractA challenge for model‐based seasonal predictions of sea ice is an accurate representation of sea ice initial conditions, particularly sparsely observed sea ice thickness (SIT). The Canadian Seasonal to Interannual Prediction System (CanSIPS) currently initializes SIT by nudging simulated values toward a model‐based climatology. To improve on this, we use sea ice data from Pan‐Arctic Ice Ocean Modeling and Assimilation System to investigate how accurately SIT can be estimated in real time using better observed and physically relevant predictors. We (1) test the skill of several predictors using maximum covariance analysis (MCA), (2) apply an approach which blends sea ice concentration and lagged (4 month averaged) sea level pressure, and (3) compare this method against the current CanSIPS initialization scheme over 1981–2012. The MCA‐based statistical model reduces SIT areal mean and temporal mean absolute errors by 48% relative to the current CanSIPS initialization and shows consistent skill estimating ice volume in all months (r = 0.95).
The Langmuir waves associated with the 1 December 2013 type II burst
Authors: Graham D. B. , Cairns Iver H. 
Published: May 2015

AbstractThe Langmuir waves associated with an interplanetary type II source region are presented. The type II burst was first observed on 29 November 2013 by STEREO A and B, with the shock crossing STEREO A on 1 December 2013. In the foreshock region upstream of the shock, 11 Langmuir‐like waveforms were recorded by STEREO A's Time Domain Sampler on three orthogonal antennas. The observed Langmuir wave electric fields are of large amplitude and aligned with the background magnetic field. Some of the waveforms show evidence of electrostatic decay, and several are consistent with Langmuir eigenmodes of density wells. Harmonic electric fields are observed simultaneously with the Langmuir waveforms and are consistent with fields produced by nonlinear currents. The beam speeds vb exciting the Langmuir waves are estimated from the waveform data, yielding speeds vb≈ (0.01–0.04)c. These are consistent with previous observations. The beam speeds are slower than those associated with type III solar radio bursts, consistent with the Langmuir wave electric fields being field aligned. The evidence found for electrostatic decay and against strong perpendicular fields, and so low‐wave number Langmuir/z‐mode waves, suggests that the dominant emission mechanisms for this type II foreshock involve electrostatic decay and nonlinear wave processes, rather than linear‐mode conversion. Harmonic radio emission via antenna mechanisms involving Langmuir waves remains possible.
Global features of the disturbance winds during storm time deduced from CHAMP observations
Authors: Xiong Chao , Lühr Hermann , Fejer Bela G. 
Published: May 2015

AbstractA wind‐driven disturbance dynamo has been postulated many decades ago. But due to the sparseness of thermospheric wind measurements, details of the phenomena could not be investigated. In this study we use the CHAMP zonal wind observations from 2001 to 2005 to investigate the global features of the disturbance winds during magnetically disturbed periods. The disturbance zonal wind is mainly westward, which increases with magnetic activity and latitude. At subauroral region, the westward zonal wind is strongly enhanced in the magnetic local time (MLT) sector from afternoon to midnight, which we relate to the plasma drift within the subauroral polarization streams. At middle and low latitudes, the disturbance zonal wind is largely independent of season. Peak values of the disturbance zonal wind occur at different MLTs for different latitudes. That is around 1800 MLT at subauroal region, with average values of about 200 m/s; around 2300 MLT at middle latitudes, with average values of about 80 m/s; and around 0300 MLT at low latitudes, with average values up to 50 m/s. The shift of the peak values of the westward disturbance zonal wind in local time at different latitudes could be considered as a response of the disturbance wind when it propagates from high to low latitudes. Further by applying for the first time a superposed epoch analysis, we show that the disturbance zonal wind responds with a delay to the sudden changes of solar wind input, which is different for the various latitudinal ranges. The propagation time of disturbance wind from the auroral region to the equator is about 3–4 h. This is consistent with the speed of traveling atmospheric disturbances. Based on CHAMP observations, we try to illustrate the whole chain of processes from the solar wind driving to the ionospheric effects at lower latitudes.
Seismogenic strain across the transition from fore‐arc slivering to collision in southern Taiwan
Authors: Lewis Jonathan C. , O'Hara Daniel J. , Rau Ruey‐Juin 
Published: May 2015

AbstractTectonic slivers have profound implications on the mechanical behavior of fore arcs and subduction zones. Southern Taiwan is characterized by precollision fore‐arc slivering that likely exerts important controls on the evolution of collision. Inversion of focal mechanism solutions for seismogenic strain reveals spatially partitioned plate motion south of Taiwan, with dip‐slip faulting nearer the Manila trench and strike‐slip faulting nearer the Luzon arc. To the north these kinematics are less clearly segregated, and both types of faults appear to occur in the same volume of crust. Further north deformation is dominated by oblique slip on potentially reactivated steep reverse faults in the collision zone. Existing work on the active fault zones in Taiwan suggests that the subduction‐to‐collision transition is marked by a releasing step between the strike‐slip fault that bounds the fore‐arc sliver and the oblique thrusts of the collision zone. This configuration may help to explain the lack of fore‐arc basement and cover exposed in the suture zone marked by the Longitudinal Valley.
Data stacking methods for isolation of normal‐mode singlets of Earth's free oscillation: Extensions, comparisons, and applications
Authors: Ding Hao , Chao Benjamin F. 
Published: May 2015

AbstractWe review three data stacking methods developed for attaining the splitting parameters of normal modes of the Earth's free oscillation, namely, SHS (spherical harmonic stacking), OSE (optimal sequence estimation), and MSE (multistation experiment), that take advantage of the spatial orthogonality of the (scalar and vector) spherical harmonic functions. We further extend these methods to broader applicability as appropriate, in particular SHS extended to matrix‐SHS (MSHS) to better accounting for the nonglobal distribution of recording stations, and OSE and MSE extended to transverse components and arbitrary harmonic degrees. We conduct synthetic numerical experiments and conclude that OSE and MSHS stackings yield superior results. Based on the lessons learned, we apply the methods on real global seismic records after the 2004 Sumatra earthquake and report the complete resolution of all singlets for 13 selected multiplets: 8 are mantle‐sensitive (1S2, 0S4, 1S4, 0S5, 0S6, 1T2, 0T4, and 0T6) and 5 inner‐core sensitive and of anomalous splitting (13S2, 10S2, 2S3, 3S2, and 11S1), among them the singlet resolution of 1T2, 0T4, 10S2, 2S3, 3S2, and 11S1 are reported for the first time.
Three‐dimensional streaming in the seabed boundary layer beneath propagating waves with an angle of attack on the current
Authors: Afzal Mohammad Saud , Holmedal Lars Erik , Myrhaug Dag 
Published: May 2015

AbstractThe effect of three‐dimensional wave‐induced streaming on the seabed boundary layer is investigated for following and opposing waves and current where the wave propagation forms a nonzero angle with the current. It is shown that the seabed boundary layer flow results from an interaction between the classical wave‐current interaction (reducing the mean velocity relative to current alone), Longuet‐Higgins streaming (forcing the flow in the wave propagation direction), and streaming caused by turbulence asymmetry in successive wave half‐cycles (forcing the flow against the wave propagation direction). For waves and current which are not colinear, the mean velocity profile exhibits a veering behavior which is strongly affected by streaming, particularly for the most wave‐dominated situations. The effect of streaming on the boundary layer flow has been investigated for different wave‐current conditions and bottom roughnesses. Visualizations are given by mean Eulerian and Lagrangian velocity profiles, as well as three‐dimensional seabed boundary layer particle trajectories. The effect of streaming decreases as the flow becomes more current dominated. The mean velocity in the current direction decreases as the roughness increases. However, the mean velocity orthogonal to the current direction increases as the roughness increases due to the lack of wave‐current interaction in this direction. An excellent agreement between the predicted and recently measured velocity profiles beneath horizontally uniform asymmetric forcing is obtained.
Spatial and temporal variability of ozone sensitivity over China observed from the Ozone Monitoring Instrument
Authors: Jin Xiaomeng , Holloway Tracey 
Published: May 2015

AbstractSurface ozone (O3) air pollution in populated regions has been attributed to emissions of nitrogen oxides (NO + NO2 = NOx) and reactive volatile organic compounds (VOCs). These constituents react with hydrogen oxide radicals (OH + HO2 = HOx) in the presence of sunlight and heat to produce O3. The question of whether to reduce NOx emissions, VOC emissions, or both is complicated by spatially and temporally heterogeneous ozone‐NOx‐VOC sensitivity. This study characterizes spatial and temporal variations in O3 sensitivity by analyzing the ratio of formaldehyde (HCHO, a marker of VOCs) to nitrogen dioxide (NO2), a metric known as the formaldehyde nitrogen ratio (FNR). Level 3 gridded retrievals from the Ozone Monitoring Instrument (OMI) aboard the NASA Aura satellite were used to calculate FNR, with our analysis focusing on China. Based on previous studies, we take FNR < 1.0 as indicating VOC‐limited regimes, FNR > 2.0 as indicating NOx‐limited regime, and FNR between 1.0 and 2.0 as indicating transitional regime (where either NOx reductions or VOC reductions would be expected to reduce O3). We find that the transitional regime is widespread over the North China Plain (NCP), the Yangtze River Delta, and the Pearl River Delta during the ozone season (defined as having near‐surface air temperatures >20°C at the early afternoon OMI overpass time). Outside of these regions, the NOx‐limited regime is dominant. Because HCHO and NO2 have distinct seasonal patterns, FNR also has a pronounced seasonality, consistent with the seasonal cycle of surface O3. Examining trends from 2005 to 2013 indicates rapid growth in NO2, especially over less‐developed areas where O3 photochemistry is NOx limited. Over this time period, HCHO decreased in southern China, where VOC emissions are dominated by biogenic sources, but increased slightly over the NCP, where VOC emissions are dominated by anthropogenic sources. A linear regression approach suggests that most of China (70% of grid cells) will be characterized by a transitional regime during the O3 season by 2030. However, in megacities such as Guangzhou, Shanghai, and Beijing, NO2 has decreased such that the chemical regime has shifted from VOC limited in 2005 to transitional in 2013.
The effect of atmospheric radiative heating by clouds on the Madden‐Julian Oscillation
Authors: Crueger Traute , Stevens Bjorn 
Published: May 2015

AbstractThis article explores how atmospheric radiative heating, due to the presence of clouds, influences the Madden‐Julian Oscillation (MJO) as simulated by four comprehensive atmosphere general circulation models. Simulations in which clouds are transparent to electromagnetic radiation (“clouds‐off”) are compared with control simulations in which clouds are allowed to interact with radiation (“clouds‐on”). Making clouds transparent to radiation leads to robust changes of the mean state: the westerly winds in the equatorial Indo‐Pacific area weaken and the precipitation reveals a shift from single to double Intertropical Convergence Zones. These changes are accompanied by weaker MJOs. Also, the moisture sensitivity of precipitation changes, however not consistently within our group of models. Further analyses show that within the active phase of intraseasonal variability, cloud‐radiative effects amplify the heating profiles compared to clouds‐off. Heating from nonradiative processes is dominated by the parameterized convection, but large‐scale heating associated with cloud microphysical processes acting on the grid‐scale modifies the shape of the heating profile, leading to a top‐heaviness when cloud‐radiative effects are accounted for. The radiative heating due to clouds slows down the phase speed of the MJO. Averaged over the entire MJO life cycle, the column‐integrated radiative heating due to clouds lags the vertically integrated moist static energy by 40°–60° of longitude (equivalently 7–10 days assuming a period of 60 days). All four models studied reveal more pronounced Kelvin waves when clouds are transparent to radiation, suggesting that cloud‐radiative effects on large‐scale heating profiles damp smaller scale, or faster, Kelvin waves and amplify MJO‐like disturbances.
High prevalence of cannabis use among Aka foragers of the Congo Basin and its possible relationship to helminthiasis
Authors: Roulette Casey J. , Kazanji Mirdad , Breurec Sébastien , Hagen Edward H. 
Published: May 2015

ObjectivesLittle is known about cannabis use in hunter‐gatherers. Therefore, we investigated cannabis use in the Aka, a population of foragers of the Congo Basin. Because cannabis contains anthelminthic compounds, and the Aka have a high prevalence of helminthiasis, we also tested the hypothesis that cannabis use might be an unconscious form of self‐medication against helminths.MethodsWe collected self‐ and peer‐reports of cannabis use from all adult Aka in the Lobaye district of the Central African Republic (n = 379). Because female cannabis use was low, we restricted sample collection to men. Using an immunoassay for Δ9‐tetrahydrocannabinol‐11‐oic acid (THCA), a urinary biomarker of recent cannabis consumption, we validated cannabis use in men currently residing in camps near a logging road (n = 62). We also collected stool samples to assay worm burden. A longitudinal reinfection study was conducted among a subsample of the male participants (n = 23) who had been treated with a commercial anthelmintic 1 year ago.ResultsThe prevalence of self‐ and peer‐reported cannabis use was 70.9% among men and 6.1% among women, for a total prevalence of 38.6%. Using a 50 ng/ml threshold for THCA, 67.7% of men used cannabis. Cannabis users were significantly younger and had less material wealth than the non‐cannabis users. There were significant negative associations between THCA levels and worm burden, and reinfection with helminths 1 year after treatment with a commercial anthelmintic.ConclusionsThe prevalence of cannabis use among adult Aka men was high when compared to most global populations. THCA levels were negatively correlated with parasite infection and reinfection, supporting the self‐medication hypothesis. Am. J. Hum. Biol. 28:5–15, 2016. © 2015 Wiley Periodicals, Inc.
Effects of cigarette smoking on rhinologic diseases: Korean National Health and Nutrition Examination Survey 2008‐2011
Authors: Lee Woo Hyun , Hong Seung‐No , Kim Hong Joong , Ahn Soyeon , Rhee Chae‐Seo , Lee Chul Hee , Kim Jeong‐Whun 
Published: May 2015

BackgroundSeveral studies have shown a relationship between cigarette smoking and general diseases of the nose in a large Asian population. The current study was conducted to better understand the effect of cigarette smoke exposure on rhinologic diseases in Koreans.MethodsData were obtained from the 2008‐2011 Korea National Health and Nutrition Examination Survey, a cross‐sectional survey of the noninstitutionalized population in Korea. Of the 37,753 people surveyed, 11,589 adult participants had completed questionnaires on rhinologic symptoms and smoking behaviors, had undergone nasal endoscopy, and had provided urine collection were enrolled. Rhinologic diseases investigated in this study included subjective olfactory dysfunction, rhinitis symptoms, chronic rhinosinusitis (CRS), and nasal septal deviation with obstructive symptoms. The relationship between disease and cigarette smoking was evaluated using multivariate regression analyses.ResultsIn South Korea, the weighted prevalence of subjective olfactory dysfunction, rhinitis symptoms, CRS, and nasal septal deviation with obstructive symptoms was 4.6%, 27.2%, 6.2%, and 4.0%, respectively. The only disease significantly associated with active smoking was CRS in participants 40 years of age and older after adjusting for age, sex, residency, house income, education, and occupation (adjusted odds ratio = 1.427, 95% confidence interval = 1.050 to 1.938). For each year of active smoking, CRS prevalence increased by 1.5%. None of the rhinologic diseases examined were associated with passive smoking.ConclusionOur study showed that CRS seems to be associated with active smoking in older participants. Considering the relatively high prevalence of CRS in Korea, further longitudinal researches for their association and prevention are required.
Nonlinear optical microscopy: Endogenous signals and exogenous probes
Authors: Ni Ming , Zhuo Shuangmu 
Published: May 2015

Nonlinear optical microscopy (NLOM) relies on nonlinear light–matter interactions to provide images from larger depths within biological structures compared to conventional confocal fluorescence microscopy. These nonlinear light–matter interactions include multiphoton excitation fluorescence (MPEF), second‐harmonic generation (SHG), coherent anti‐Stokes Raman scattering (CARS), and stimulated Raman scattering (SRS). This review discusses the theories of and instrumentation for various NLOM techniques, with a particular focus on endogenous signals and exogenous probes. These signals and probes expand the breadth of information that optical imaging can provide. We also discuss the application of NLOM in biomedical research, including tissue engineering, drug delivery and clinical diagnostics. Current technological limitations are also discussed.
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Fujiwara–Moritani Reaction of Weinreb Amides using a Ruthenium‐Catalyzed C−H Functionalization Reaction
Authors: Das Riki , Kapur Manmohan 
Published: May 2015

AbstractThe ruthenium‐catalyzed Fujiwara–Moritani reaction (oxidative‐Heck reaction) of Weinreb amides is reported herein. The reaction affords exclusively ortho‐C−H olefination products, has excellent substrate scope and tolerates halogen functionalities, which increase the synthetic utility of the method. A variety of activated olefins as well as styrenes can be employed as coupling partners.