bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exponential Stability of the Energy of the Wave Equation with Variable Coefficients and a Boundary Distributed Delay
Authors: Liu Wenjun 
Published: October 2014

Abstract
In this paper, we consider a wave equation with space variable coefficients. Due to physical considerations, a distributed delay damping is acted on the part of the boundary. Under suitable assumptions, we prove the exponential stability of the energy based on the use of Riemannian geometry method, the perturbed energy argument, and some observability inequalities. From the applications point of view, our results may provide some qualitative analysis and intuition for the researchers in fields such as engineering, biophysics, and mechanics. And the method is rather general and can be adapted to other evolution systems with variable coefficients (e. g. elasticity plates) as well.
Hydromagnetic Mixed Convective Two-Phase Flow of Couple Stress and Viscous Fluids in an Inclined Channel
Authors: Abbas Zaheer , Hasnain Jafar , Sajid Muhammad 
Published: October 2014

Abstract
An analysis is carried out to study magnetohydrodynamic (MHD) flow and heat transfer of two immiscible fluids in an inclined channel. The channel is filled with couple stress fluid in one region and a viscous fluid in the other region. The viscous fluid is assumed to be electrically conducting. The governing equations are modelled using the fully developed flow conditions. A closed form solutions of velocity and the temperature profiles are obtained by using perturbation method. The physical interpretation of the emerging parameters of interest on the velocity and temperature distributions are shown through graphs and discussed in detail.
Observations and modeling of slow‐sinking particles in the twilight zone
Authors: Villa‐Alfageme M. , de Soto F. , Le Moigne F. A. C. , Giering S. L. C. , Sanders R. , García‐Tenorio R. 
Published: October 2014

AbstractThe biological carbon pump (BCP) transfers carbon from the surface ocean into the oceans' interior, mainly in the form of sinking particles with an organic component, and thereby keeps atmospheric CO2 at significantly lower levels than if the oceans were abiotic. The depth at which these sinking particles are remineralized is a key control over atmospheric CO2. Particle sinking speed is likely to be a critical parameter over remineralization depth. Carbon export is usually controlled by large, rapidly sinking particles (>150 m·d−1); however, under some circumstances sinking velocity distributions are strongly bimodal with a significant fraction of total flux being carried by slowly (<10 m·d−1) sinking particles. Therefore, there is an interest in determining sinking particle velocities and their variations with depth, as well as in understanding the interplay between sinking velocity distributions and carbon export. Here, we use profiles of total and particulate concentrations of the naturally occurring radionuclide pair 210Po‐210Pb from the Porcupine Abyssal Plain (PAP) site (48°N, 16.5°W) to estimate depth variation in particle sinking speed using a one‐box model and inverse techniques. Average sinking speeds increase from 60 ± 30 m·d−1 at 50 m, to 75 ± 25 m·d−1 and 90 ± 20 m·d−1 at 150 and 500 m. Furthermore, a sensitivity analysis suggests that at the PAP site the measured 210Po profiles are inconsistent with the usually assumed sinking velocities of 200 m·d−1. We hypothesize that a trend of increasing velocity with depth might be caused by a gradual loss of slow‐sinking material with depth, a factor with significant implications for regional carbon budgets.
Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep Water
Authors: Silvester J. Mead , Lenn Yueng‐Djern , Polton Jeff A. , Rippeth Tom P. , Maqueda M. Morales 
Published: October 2014

AbstractIn the Southern Ocean, small‐scale turbulence causes diapycnal mixing which influences important water mass transformations, in turn impacting large‐scale ocean transports such as the Meridional Overturning Circulation (MOC), a key controller of Earth's climate. We present direct observations of mixing over the Antarctic continental slope between water masses that are part of the Southern Ocean MOC. A 12 h time series of microstructure turbulence measurements, hydrography, and velocity observations off Elephant Island, north of the Antarctic Peninsula, reveals two concurrent bursts of elevated dissipation of O(10−6) W kg−1, resulting in heat fluxes ∼10 times higher than basin‐integrated Drake Passage estimates. This occurs across the boundary between adjacent adiabatic upwelling and downwelling overturning cells. Ray tracing to nearby topography shows mixing between 300 and 400 m is consistent with the breaking of locally generated internal tidal waves. Since similar conditions extend to much of the Antarctic continental slope where these water masses outcrop, diapycnal mixing may contribute significantly to upwelling.
Will Arctic sea ice thickness initialization improve seasonal forecast skill?
Authors: Day J. J. , Hawkins E. , Tietsche S. 
Published: October 2014

AbstractArctic sea ice thickness is thought to be an important predictor of Arctic sea ice extent. However, coupled seasonal forecast systems do not generally use sea ice thickness observations in their initialization and are therefore missing a potentially important source of additional skill. To investigate how large this source is, a set of ensemble potential predictability experiments with a global climate model, initialized with and without knowledge of the sea ice thickness initial state, have been run. These experiments show that accurate knowledge of the sea ice thickness field is crucially important for sea ice concentration and extent forecasts up to 8 months ahead, especially in summer. Perturbing sea ice thickness also has a significant impact on the forecast error in Arctic 2 m temperature a few months ahead. These results suggest that advancing capabilities to observe and assimilate sea ice thickness into coupled forecast systems could significantly increase skill.
AERUS‐GEO: A newly available satellite‐derived aerosol optical depth product over Europe and Africa
Authors: Carrer D. , Ceamanos X. , Six B. , Roujean J.‐L. 
Published: October 2014

AbstractThis article presents a new aerosol optical depth (AOD) product delivered in near real time by the ICARE Data and Services Center to the scientific community. The AERUS‐GEO (Aerosol and surface albEdo Retrieval Using a directional Splitting method‐application to GEOstationary data) product is derived from observations from the Meteosat Second Generation (MSG) geostationary satellite covering Europe, Africa, and part of Asia and South America. The retrieval method exploits the directional information contained in the series of 96 MSG observations per day of the Earth's disk to derive a daily averaged AOD. The performances of this product are similar to those of other widely used satellite‐derived AOD. This article illustrates the advantages of the spatial (3 km at best) and temporal (daily) resolution of the AERUS‐GEO product to monitor particular aerosol activity (e.g., volcanic eruptions) or to study given phenomena (e.g., the impact of topography on aerosol loading).
Regional precipitation simulations for the mid‐1970s shift and early‐2000s hiatus
Authors: Meehl Gerald A. , Teng Haiyan 
Published: October 2014

AbstractIt has been demonstrated that climate models initialized with observations produce better simulations of Pacific sea surface temperature (SST) patterns than uninitialized simulations for the two major climate regime changes of the last 40 years, the mid‐1970s climate shift and early‐2000s hiatus. A fundamental feature of these hindcasts is the simulation of the SST anomalies associated with the phase of the Interdecadal Pacific Oscillation (IPO). Since regional precipitation patterns over selected land areas in south Asia, Australia, and North America are known to be affected by SST patterns over the Pacific, it is shown that the initialized climate model simulations produce qualitatively better agreement with observations for regional precipitation anomalies in those regions compared to uninitialized climate models. Though the signals are small, the anomalies are consistent with our physical process‐based understanding of precipitation responses over certain land areas during different IPO phases.
Constraining Cretaceous subduction polarity in eastern Pacific from seismic tomography and geodynamic modeling
Authors: Liu Lijun 
Published: October 2014

AbstractInterpretation of recent mantle seismic images below the America ignited a debate on the Cretaceous subduction polarity in the eastern Pacific Ocean. The traditional view is that the massive vertical slab wall under eastern North America resulted from an eastward Farallon subduction. An alternative interpretation attributes this prominent seismic structure to a westward subduction of the North American Plate against a stationary intraoceanic trench. Here I design quantitative subduction models to test these two scenarios, using their implied plate kinematics as velocity boundary conditions. Modeling results suggest that the westward subduction scenario could not produce enough slab volume as seismic images reveal, as is due to the overall slow subduction rate (~2.5 cm/yr). The results favor the continuous eastward Farallon subduction scenario, which, with an average convergence rate of >10 cm/yr prior to the Eocene, can properly generate both the volume and the geometry of the imaged lower mantle slab pile. The eastward subduction model is also consistent with most Cretaceous geological records along the west coast of North America.
Effects of discreteness of chorus waves on quasilinear diffusion‐based modeling of energetic electron dynamics
Authors: Tao Xin , Bortnik Jacob , Albert Jay M. , Thorne Richard M. , Li Wen 
Published: October 2014

AbstractChorus waves are typically observed as a series of discrete, narrowband rising or falling tone elements, as opposed to a continuous uniform band, as it is often modeled. The effects of this discreteness on the applicability of quasilinear theory to interactions between electrons and parallel‐propagating chorus waves in a dipole field are investigated using test particle simulations. Previous work indicated that quasilinear theory might not be directly applicable, because chorus elements are coherent or quasi‐coherent. Nonlinear processes such as phase trapping and bunching were demonstrated by modeling a chorus element using a single wave. Here we represent a chorus wave field with a series of coherent elements with subpacket structures using a previously developed method involving test particle simulations to explore the applicability of quasilinear theory. By comparing electron distribution functions from test particle simulations and quasilinear predictions, we demonstrate that, besides the wave amplitude, the discreteness of chorus waves also affects the applicability of quasilinear theory. When chorus elements are close to each other and the wave amplitude is small, quasilinear theory can well describe the evolution of the electron distribution. However, when chorus elements are widely separated in space and time, the discreteness of chorus might reduce the possibility of resonant interactions between electrons and chorus. Nonlinear effects of chorus waves on electrons are also shown using the current model. The method presented in this work should be helpful for investigating the applicability of quasilinear theory in general situations. Our results should be important to understanding and modeling electrons dynamics due to interactions with chorus.
Bayesian inference for ultralow velocity zones in the Earth's lowermost mantle: Complex ULVZ beneath the east of the Philippines
Authors: Pachhai S. , Tkalčić H. , Dettmer J. 
Published: October 2014

AbstractUltralow velocity zones (ULVZs) are small‐scale structures with a sharp decrease in S and P wave velocity, and an increase in the density on the top of the Earth's core‐mantle boundary. The ratio of S and P wave velocity reduction and density anomaly are important to understanding whether ULVZs consist of partial melt or chemically distinct material. However, existing methods such as forward waveform modeling that utilize 1‐D and 2‐D Earth‐structure models face challenges when trying to uniquely quantify ULVZ properties because of inherent nonuniqueness and nonlinearity. This paper develops a Bayesian inversion for ULVZ parameters and uncertainties with rigorous noise treatment to address these challenges. The posterior probability density of the ULVZ parameters (the solution to the inverse problem) is sampled by the Metropolis‐Hastings algorithm. To improve sampling efficiency, parallel tempering is applied by simulating a sequence of tempered Markov chains in parallel and allowing information exchange between chains. First, the Bayesian inversion is applied to simulated noisy data for a realistic ULVZ model. Then, measured data sampling the lowermost mantle under the Philippine Sea are considered. Cluster analysis and visual waveform inspection suggest that two distinct classes of ScP (S waves converted to, and reflected as, P waves) waves exist in this region. The distinct waves likely correspond to lateral variability in the lowermost mantle properties in a NE‐SW direction. For the NE area, Bayesian model selection identifies a two‐layer model with a gradual density increase as a function of depth as optimal. This complex ULVZ structure can be due to the percolation of iron‐enriched, molten material in the lowermost mantle. The results for the SW area are more difficult to interpret, which may be due to the limited number of data available (too few waveforms to appropriately reduce noise) and/or complex 2‐D and 3‐D structures that cannot be explained properly by the 1‐D models required by our inversion approach. In particular, the complex waveforms require highly layered 1‐D models to fit the data. These models appear physically unreasonable and suggest that the SW region cannot be explained by 1‐D structure.
Formulation of coseismic changes in Earth rotation and low‐degree gravity field based on the spherical Earth dislocation theory
Authors: Xu Changyi , Sun Wenke , Chao B. Fong 
Published: October 2014

AbstractIn this paper we present analytical formulas to compute the coseismic Earth rotation change (polar motion and length of day) and low‐degree gravity field change based on a spherical dislocation theory. Using the preliminary reference Earth model and our formulas, we calculate coseismic changes in Earth's rotation and low‐degree Stokes coefficients caused by the four largest earthquakes since 1960. The results verify that the present method is consistent with previous studies, but the method cannot be verified by the observations. A case study on the 2011 Tohoku‐Oki earthquake (Mw 9.0) indicates that the coseismic Earth rotation change depends on the magnitude and source parameters, and results show a difference between a point source and finite fault model. We also investigate the effect of seawater redistribution on coseismic Earth rotation change, but the effect is small and can be neglected.
Space Weather Observations by GNSS Radio Occultation: From FORMOSAT‐3/COSMIC to FORMOSAT‐7/COSMIC‐2
Authors: Yue Xinan , Schreiner William S. , Pedatella Nicholas , Anthes Richard A. , Mannucci Anthony J. , Straus Paul R. , Liu Jann‐Yenq 
Published: October 2014

AbstractThe joint Taiwan‐United States FORMOSAT‐3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission, hereafter called COSMIC, is the first satellite constellation dedicated to remotely sense Earth's atmosphere and ionosphere using a technique called Global Positioning System (GPS) radio occultation (RO). The occultations yield abundant information about neutral atmospheric temperature and moisture as well as space weather estimates of slant total electron content, electron density profiles, and an amplitude scintillation index, S4. With the success of COSMIC, the United States and Taiwan are moving forward with a follow‐on RO mission named FORMOSAT‐7/COSMIC‐2 (COSMIC‐2), which will ultimately place 12 satellites in orbit with two launches in 2016 and 2019. COSMIC‐2 satellites will carry an advanced Global Navigation Satellite System (GNSS) RO receiver that will track both GPS and Russian Global Navigation Satellite System signals, with capability for eventually tracking other GNSS signals from the Chinese BeiDou and European Galileo system, as well as secondary space weather payloads to measure low‐latitude plasma drifts and scintillation at multiple frequencies. COSMIC‐2 will provide 4–6 times (10–15X in the low latitudes) the number of atmospheric and ionospheric observations that were tracked with COSMIC and will also improve the quality of the observations. In this article we focus on COSMIC/COSMIC‐2 measurements of key ionospheric parameters.
Enzymatic Fabrication of High‐Density RNA Arrays
Authors: Wu Cheng‐Hsien , Holden Matthew T. , Smith Lloyd M. 
Published: October 2014

AbstractA powerful new strategy for the fabrication of high‐density RNA arrays is described. A high‐density DNA array is fabricated by standard photolithographic methods, the surface‐bound DNA molecules are enzymatically copied into their RNA complements from a surface‐bound RNA primer, and the DNA templates are enzymatically destroyed, leaving behind the desired RNA array. The strategy is compatible with 2′‐fluoro‐modified (2′F) ribonucleoside triphosphates (rNTPs), which may be included in the polymerase extension reaction to impart nuclease resistance and other desirable characteristics to the synthesized RNAs. The use and fidelity of the arrays are explored with DNA hybridization, DNAzyme cleavage, and nuclease digestion experiments.
Mapping Platinum Species in Polymer Electrolyte Fuel Cells by Spatially Resolved XAFS Techniques
Authors: Takao Shinobu , Sekizawa Oki , Nagamatsu Shin‐ichi , Kaneko Takuma , Yamamoto Takashi , Samjeské Gabor , Higashi Kotaro , Nagasawa Kensaku , Tsuji Takuya , Suzuki Motohiro , Kawamura Naomi , Mizumaki Masaichiro , Uruga Tomoya , Iwasawa Yasuhiro 
Published: October 2014

AbstractThere is limited information on the mechanism for platinum oxidation and dissolution in Pt/C cathode catalyst layers of polymer electrolyte fuel cells (PEFCs) under the operating conditions though these issues should be uncovered for the development of next‐generation PEFCs. Pt species in Pt/C cathode catalyst layers are mapped by a XAFS (X‐ray absorption fine structure) method and by a quick‐XAFS(QXAFS) method. Information on the site‐preferential oxidation and leaching of Pt cathode nanoparticles around the cathode boundary and the micro‐crack in degraded PEFCs is provided, which is relevant to the origin and mechanism of PEFC degradation.
Effects of American ginseng on pharmacokinetics of 5‐fluorouracil in rats
Authors: He Yi‐Sheng , Sun Wei , Wang Chong‐Zhi , Qi Lian‐Wen , Yang Jie , Li Ping , Wen Xiao‐Dong , Yuan Chun‐Su 
Published: October 2014

AbstractThe pharmacokinetics of 5‐fluorouracil (5‐FU) in combination with or without American ginseng (seven‐consecutive days oral dose) in rats were evaluated using liquid chromatography–electrospray ionization–mass spectrometry (LC‐MS). Chromatographic separation was performed on a reverse LC column within a total run time of 6.5 min, which allowed for a relatively quick analysis. The limit of quantification for 5‐FU was 15 ng/mL and this method was linear over 15–50,000 ng/mL. This method supported stabilizing determination of the plasma concentration of 5‐FU over a period of 24 h. Precision both interday and intraday (coefficient of variation) was within 14% and accuracy (relative error) ranged from −5 to 14%. In view of the observed pharmacokinetic parameters, including maximum concentration, time to maximum concentration, area under the concentration–time curve (AUC), mean residence time, elimination half‐life and clearance, our results showed no significant differences in all of the pharmacokinetic parameters between the ginseng co‐treated group and 5‐FU alone group. Some increase in AUC was observed in 5‐FU plus ginseng group; however, the difference did not reach statistical significance compared with 5‐FU alone. It appeared that American ginseng administration did not significantly alter the kinetics of 5‐FU. More studies are still needed to confirm our results. Copyright © 2014 John Wiley & Sons, Ltd.
Use of specific polysaccharide‐immobilized monodisperse poly(glycidyl methacrylate) core–silica shell microspheres for affinity purification of lectins
Authors: Antonyuk Volodymyr , Grama Silvia , Plichta Zdeněk , Magorivska Iryna , Horak Daniel , Stoika Rostyslav 
Published: October 2014

AbstractImmobilization of polysaccharides (yeast mannan and gum arabic) on the macroporous poly(glycidyl methacrylate) monodisperse microspheres coated with silica (SiO2)‐containing amino groups on the surface was used to prepare affinity sorbents for lectin purification. The efficiency of isolating mannose specific Pisum sativum lectin was demonstrated on sorbent with immobilized yeast mannan and that of galactose specific Glycine hispida lectin on sorbent with immobilized gum arabic. The microspheres with immobilized polysaccharides can be used for selecting an affinity sorbent for purification of other mannose‐ and galactose‐specific lectins. In contrast to yeast mannan, the gum arabic immobilized on the microspheres possesses much narrower specificity and is suitable for purification of only those galactose specific lectins which interact well with l‐rhamnose or l‐arabinose. The synthesized macroporous particles are capable of immobilizing 50 mg of polysaccharide per 1 g of the matrix, which is 10 times higher than the capacity of epoxy‐activated Sepharose 6B. That makes it possible to obtain the same lectin quantity using a column of 10 times smaller volume. Another advantage of novel affinity sorbents comparing corresponding Sepharose gels is the possibility of sorbent drying after use. Copyright © 2014 John Wiley & Sons, Ltd.
Student Voice for School‐Climate Improvement: A Case Study of an Urban Middle School
Authors: Voight Adam 
Published: October 2014

AbstractThis case study used a student voice program in an urban middle school in the southeastern United States to examine the validity of three theoretically derived pathways through which student voice may affect positive school climate. First, using a youth participatory action research process to identify barriers to learning, analyse their root causes, and advocate for solutions to school administration allowed students to influence minor school policies and implement anti‐bullying, classroom‐behaviour‐monitoring, and experiential‐learning initiatives. However, there were challenges to making these policy and practice changes systemic. Second, relationships were formed and strengthened as a byproduct of student participant and staff collaboration in program activities. However, the program may have contributed to an ingroup–outgroup dynamic between participants and other peers. Third, students who participated in the program developed citizenship competencies, and their development may have promoted broader prosocial norms among the student body, though evidence was inconsistent. Study findings suggest that future research examine how variations in the implementation of student voice initiatives can maximize the contribution to a positive school climate in urban schools. Findings also suggest that practitioners should ensure that student teams be representative of a multitude of student identities. Copyright © 2014 John Wiley & Sons, Ltd.