bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tab location effect on supersonic jet mixing
Authors: Maruthupandiyan K. , Rathakrishnan E. 
Published: June 2018

ABSTRACTAerodynamic mixing of a Mach 2 jet controlled with rectangular flat tab with length equal to the nozzle exit diameter, placed at locations 0.25D, 0.5D and 0.75D, downstream of the nozzle exit, has been studied in the presence of different levels of pressure gradients corresponding to nozzle pressure ratio (NPR) range from 3 to 8. The mixing modification associated with shifted tabs is compared with the mixing caused by the same tab at the nozzle exit (0D). The aerodynamic mixing caused by the mass transporting small-scale vortices shed from the edges of the tab placed at the shifted position is found to be appreciably larger than the tab at nozzle exit, for some levels of pressure gradient. For some other levels of nozzle expansion, mixing caused by the shifted tab is comparable to that of tab at nozzle exit. The waves present in the core of the jet controlled with shifted tab were found to be weaker than that of the jet controlled with tab at nozzle exit. At a marginally underexpanded state corresponding to NPR 8, jet core length reduction caused by the tab at 0.75D is about 39.21%, which is closer to the reduction of 40.2%, caused by the tab at 0D. The corresponding core length reduction for tab at 0.25D and 0.5D are 38.16% and 20%, respectively.
DYNAMIC HEDGING STRATEGIES FOR CASH BALANCE PENSION PLANS
Authors: Zhu Xiaobai , Hardy Mary R. , Saunders David 
Published: June 2018

AbstractCash balance pension plans with crediting rates linked to long bond yields are relatively common in the United States, but their liabilities are proving very challenging to hedge. In this paper, we consider dynamic hedge strategies using the one-factor and two-factor Hull White models, based on results for the liability valuation from Hardy et al. (2014). The strategies utilise simple hedge portfolios combining one or two zero-coupon bonds, and a money market account. We assess the effectiveness of the strategies by considering how accurately each one would have hedged a 5-year cash balance liability through the past 20 years, using real-world returns and crediting rates, and assuming parameters calibrated using the information available at the time. We show that there is considerable impact of model and parameter uncertainty, with additional, less severe impact from discrete hedging error and transactions costs. Despite this, the dynamic hedge strategies do manage to stabilize surplus substantially, even through the turbulence of the past two decades.
Clustering and increased settling speed of oblate particles at finite Reynolds number
Authors: Fornari Walter , Ardekani Mehdi Niazi , Brandt Luca 
Published: June 2018

We study the settling of rigid oblates in a quiescent fluid using interface-resolved direct numerical simulations. In particular, an immersed boundary method is used to account for the dispersed solid phase together with lubrication correction and collision models to account for short-range particle–particle interactions. We consider semi-dilute suspensions of oblate particles with aspect ratio $AR=1/3$ and solid volume fractions $\unicode[STIX]{x1D719}=0.5{-}10\,\%$. The solid-to-fluid density ratio $R=1.02$ and the Galileo number (i.e. the ratio between buoyancy and viscous forces) based on the diameter of a sphere with equivalent volume $Ga=60$. With this choice of parameters, an isolated oblate falls vertically with a steady wake with its broad side perpendicular to the gravity direction. At this $Ga$, the mean settling speed of spheres is a decreasing function of the volume $\unicode[STIX]{x1D719}$ and is always smaller than the terminal velocity of the isolated particle, $V_{t}$. On the contrary, in dilute suspensions of oblate particles (with $\unicode[STIX]{x1D719}\leqslant 1\,\%$), the mean settling speed is approximately 33 % larger than $V_{t}$. At higher concentrations, the mean settling speed decreases becoming smaller than the terminal velocity $V_{t}$ between $\unicode[STIX]{x1D719}=5\,\%$ and 10 %. The increase of the mean settling speed is due to the formation of particle clusters that for $\unicode[STIX]{x1D719}=0.5{-}1\,\%$ appear as columnar-like structures. From the pair distribution function we observe that it is most probable to find particle pairs almost vertically aligned. However, the pair distribution function is non-negligible all around the reference particle indicating that there is a substantial amount of clustering at radial distances between 2 and $6c$ (with $c$ the polar radius of the oblate). Above $\unicode[STIX]{x1D719}=5\,\%$, the hindrance becomes the dominant effect, and the mean settling speed decreases below $V_{t}$. As the particle concentration increases, the mean particle orientation changes and the mean pitch angle (the angle between the particle axis of symmetry and gravity) increases from $23^{\circ }$ to $47^{\circ }$. Finally, we increase $Ga$ from 60 to 140 for the case with $\unicode[STIX]{x1D719}=0.5\,\%$ and find that the mean settling speed (normalized by $V_{t}$) decreases by less than 1 % with respect to $Ga=60$. However, the fluctuations of the settling speed around the mean are reduced and the probability of finding vertically aligned particle pairs increases.
The anti-inflammatory effects of erythromycin, clarithromycin, azithromycin and roxithromycin on histamine-induced otitis media with effusion in guinea pigs
Authors: Ersoy B , Aktan B , Kilic K , Sakat M S , Sipal S 
Published: June 2018

AbstractBackgroundOtitis media with effusion is a clinical manifestation characterised by inflammation of middle-ear mucosa. This study investigated the therapeutic effect of erythromycin, clarithromycin, azithromycin and roxithromycin on a histamine-induced animal model of otitis media with effusion.MethodsThe animals were divided into five groups, receiving erythromycin, clarithromycin, azithromycin, roxithromycin or saline solution. The guinea pigs in the study groups received erythromycin (40 mg/kg/day), clarithromycin (15 mg/kg/day), azithromycin (10 mg/kg/day) or roxithromycin (10 mg/kg/day) for 3 days by gastric tube. Four hours after the end of the administration, histamine solution was injected into the right middle ear.ResultsThe lowest neutrophil density value obtained using stereological techniques was in the azithromycin group (0.86 ± 0.25 × 10−5/μm3), while the highest value was observed in the control group (6.68 ± 3.12 × 10−5/μm3). The anti-inflammatory properties of clarithromycin, azithromycin and roxithromycin were similar to one another, but better than that of erythromycin.ConclusionThe use of macrolide antibiotics is recommended, as they show antibacterial and anti-inflammatory efficacy in otitis media with effusion.
Spoken second language words activate native language orthographic information in late second language learners
Authors: VEIVO OUTI , PORRETTA VINCENT , HYÖNÄ JUKKA , JÄRVIKIVI JUHANI 
Published: June 2018

ABSTRACTThis study investigated the time course of activation of orthographic information in spoken word recognition with two visual world eye-tracking experiments in a task where second language (L2) spoken word forms had to be matched with their printed referents. Participants (n= 64) were native Finnish learners of L2 French ranging from beginners to highly proficient. In Experiment 1, L2 targets (e.g.,<cidre>/sidʀ/) were presented with either orthographically overlapping onset competitors (e.g.,<cintre>/sɛ̃tʀ/) or phonologically overlapping onset competitors (<cycle>/sikl/). In Experiment 2, L2 targets (e.g.,<paume>/pom/) were associated with competitors in Finnish, L1 of the participants, in conditions symmetric to Experiment 1 (<pauhu>/pauhu/ vs.<pommi>/pom:i/). In the within-language experiment (Experiment 1), the difference in target identification between the experimental conditions was not significant. In the between-language experiment (Experiment 2), orthographic information impacted the mapping more in lower proficiency learners, and this effect was observed 600 ms after the target word onset. The influence of proficiency on the matching was nonlinear: proficiency impacted the mapping significantly more in the lower half of the proficiency scale in both experiments. These results are discussed in terms of coactivation of orthographic and phonological information in L2 spoken word recognition.
STAKEHOLDER INVOLVEMENT IN THE HEALTH TECHNOLOGY ASSESSMENT PROCESS IN LATIN AMERICA
Authors: Pichon-Riviere Andres , Soto Natalie , Augustovski Federico , Sampietro-Colom Laura 
Published: June 2018

Objectives:Latin American countries are taking important steps to expand and strengthen universal health coverage, and health technology assessment (HTA) has an increasingly prominent role in this process. Participation of all relevant stakeholders has become a priority in this effort. Key issues in this area were discussed during the 2017 Latin American Health Technology Assessment International (HTAi) Policy Forum.Methods:The Forum included forty-one participants from Latin American HTA agencies; public, social security, and private insurance sectors; and the pharmaceutical and medical device industry. A background paper and presentations by invited experts and Forum members supported discussions. This study presents a summary of these discussions.Results:Stakeholder involvement in HTA remains inconsistently implemented in the region and few countries have established formal processes. Participants agreed that stakeholder involvement is key to improve the HTA process, but the form and timing of such improvements must be adapted to local contexts. The legitimization of both HTA and decision-making processes was identified as one of the main reasons to promote stakeholder involvement; but to be successful, the entire system of assessment and decision making must be properly staffed and organized, and certain basic conditions must be met, including transparency in the HTA process and a clear link between HTA and decision making.Conclusions:Participants suggested a need for establishing clear rules of participation in HTA that would protect HTA producers and decision makers from potentially distorting external influences. Such rules and mechanisms could help foster trust and credibility among stakeholders, supporting actual involvement in HTA processes.
Whistler Influence on the Overall Very Low Frequency Wave Intensity in the Upper Ionosphere
Authors: Záhlava J. , Němec F. , Pincon J. L. , Santolík O. , Kolmašová I. , Parrot M. 
Published: June 2018

AbstractWe investigate the influence of lightning‐generated whistlers on the overall intensity of electromagnetic waves measured by the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions spacecraft (2004–2010, quasi Sun‐synchronous polar orbit with an altitude of about 700 km) at frequencies below 18 kHz. Whistler occurrence rate evaluated using an onboard neural network designed for automated whistler detection is used to distinguish periods of high and low whistler occurrence rates. It is shown that especially during the night and particularly in the frequency‐geomagnetic latitude intervals with a low average wave intensity, contribution of lightning‐generated whistlers to the overall wave intensity is significant. At frequencies below 1 kHz, where all six electromagnetic wave components were measured during specific intervals, the study is accompanied by analysis of wave propagation directions. When we limit the analysis only to fractional‐hop whistlers, which propagate away from the Earth, we find a reasonable agreement with results obtained from the whole data set. This also confirms the validity of the whistler occurrence rate analysis at higher frequencies.
Diachronous Growth of the Altyn Tagh Mountains: Constraints on Propagation of the Northern Tibetan Margin From (U‐Th)/He Dating
Authors: Shi Wenbei , Wang Fei , Yang Liekun , Wu Lin , Zhang Weibin 
Published: June 2018

AbstractThe sinistral Altyn Tagh strike‐slip fault demarcates the northern boundary of the Qinghai‐Tibetan Plateau; however, the significance and timing of activity along the fault are debated. Here new apatite and zircon (U‐Th)/He data are presented, revealing the exhumation history of the Altyn Tagh Mountains from crustal depths of ~2–7 km. Studies of rock samples from the Altun Shan region show that they were located close to the surface during the Early Cretaceous and remained so until about 40 Ma. Samples from the Subei and Dangjin Pass areas, on the other hand, record a period of rapid exhumation at 20 ± 2 Ma, and samples from the Qiemo area record a period of continuous exhumation between ~20 and 12 Ma at a rate of
mm/year, plus a further rapid cooling event at 7–5.5 Ma. Thus, significantly more exhumation has occurred toward the southwestern section of the Altyn Tagh Fault Zone, indicating a decrease in tectonic uplift toward the northeast since the Miocene. During the late Miocene, the Tarim Block began to subduct beneath the northern Tibetan margin, resulting in rapid exhumation of the central section of the Altyn Tagh Fault Zone. In accordance with previous studies, the present results support a model of northward propagation and expansion of the Qinghai‐Tibetan Plateau during the Cenozoic.
Crustal Deformation Following Great Subduction Earthquakes Controlled by Earthquake Size and Mantle Rheology
Authors: Sun Tianhaozhe , Wang Kelin , He Jiangheng 
Published: June 2018

AbstractAfter a great subduction earthquake, viscoelastic stress relaxation causes opposing motion of Earth's surface in the strike‐normal direction, with the dividing boundary located roughly above the downdip termination of the rupture. As the effect of the viscoelastic relaxation decays with time, the effect of the relocking of the megathrust becomes increasingly dominant to cause the dividing boundary to migrate away from the rupture zone, eventually leading to wholesale landward motion. The evolution of the postseismic deformation is controlled not only by mantle viscosity but also by the size of the earthquake. Large coseismic fault slip induces greater stress perturbation that takes a longer time to relax, and a greater rupture length along‐strike results in a pattern of postseismic viscous mantle flow less efficient for stress relaxation. Here we employ spherical‐Earth finite element models of Burgers rheology to quantify postseismic deformation processes for ten 8.0 ≤ Mw ≤ 9.5 subduction earthquakes. Using geodetic data as constraints, we reconstruct spatiotemporally continuous evolution of the postseismic deformation following each earthquake. We comparatively examine the “reference time” when the dividing boundary of the opposing motion passes through the map view location of the 50‐km depth contour of the subduction interface. Our results suggest a positive dependence of the reference time on earthquake size, although site‐ and/or event‐specific factors such as subduction rate, afterslip, and postseismic locking state of the megathrust also affect the evolution. Upper mantle viscosities constrained by available geodetic observations show somewhat different values between subduction zones located far from one another.
Competition Between Crystallization‐Induced Expansion and Creep Compaction During Gypsum Formation, and Implications for Serpentinization
Authors: Skarbek Rob M. , Savage Heather M. , Kelemen Peter B. , Yancopoulos Demetra 
Published: June 2018

AbstractDeformation caused by reaction‐driven volume increases is an important process in many geological settings. The interaction of rocks with reactive fluids can change permeability and reactive surface area, leading to a large variety of feedbacks. Gypsum (CaSO4·2H2O) is an ideal material to study these processes. It forms rapidly at room temperature via bassanite (CaSO4·[1/2]H2O) hydration and is commonly used as an analog for rocks in high‐temperature, high‐pressure conditions. We conducted uniaxial deformation experiments on porous bassanite aggregates to study the effects of applied axial load σa on deformation during the formation of gypsum. While hydration of bassanite involves a solid volume increase, gypsum exhibits significant creep compaction when in contact with water. These two processes occur simultaneously. Samples exhibited an initial phase of deformation followed by a slower secondary phase. A particular value of σa separates expansion from compaction during each of the deformation phases. At σa≤150 kPa, samples expanded initially; for σa≥230 kPa, samples compacted initially. Up to σa≈3.2 MPa, samples expanded after compacting initially, while for σa≥3.6 MPa, no further deformation or continued compaction occurred. This behavior implies that crystallization‐induced stresses depend on porosity and reaction extent such that larger stresses cannot be generated by the reaction. We explain aspects of the observed behavior with a model that predicts strain evolution using kinetic relationships for the reaction and creep rates and consider the implications of our results for reaction‐induced fracturing during serpentinization.
WRF‐Chem Simulation of an East Asian Dust‐Infused Baroclinic Storm (DIBS)
Authors: Caffrey Peter F. , Fromm Michael D. , Kablick George P. 
Published: June 2018

AbstractObservations of dust‐infused baroclinic storm (DIBS) clouds (Fromm et al., 2016, https://doi.org/10.1002/2016GL071801) have revealed Saharan and Asian storm systems with mineral dust mixed with overrunning cirrus shield clouds at altitudes of 8–10 km. The unique characteristics observed in these clouds, including intense Cloud‐Aerosol LIdar with Orthogonal Polarization lidar backscatter and large daytime 3.9‐ to 11‐μm brightness temperature differences (indicating relatively small ice crystals), have prompted this modeling study to determine the mineral dust pathway and dynamics, if any, through an observed DIBS. We use the Advanced Weather Research and Forecasting Model with the chemistry model (WRF‐Chem) and constrained with the WRF data assimilation system (WRF‐DA) to conduct a reanalysis of an East Asian DIBS from 6 to 11 April 2010. Desert dust emission via the Global Ozone Chemistry Aerosol Radiation and Transport dust emission scheme (Ginoux et al., 2001, https://doi.org/10.1029/2000JD000053) and transport from both the Taklimakan and Gobi deserts is simulated within WRF‐Chem with the Model for Simulating Aerosol Interactions and Chemistry aerosol treatment (Zaveri et al., 2008, https://doi.org/10.1029/2007JD008782). In‐line air mass trajectories were used to source and trace dust transport from the storm spin‐up through dissipation 4 days later. Results show rapid dust transport from the Gobi desert to cirrus cloud tops via the warm conveyor belt mechanism, with the dust mixed throughout the cloud at altitudes from 5 to 10 km. Results are verified by good qualitative agreement with Cloud‐Aerosol LIdar with Orthogonal Polarization observations at several different moments in the DIBS cycle, including an elevated layer of dust that remains after storm cloud dissipation. These results confirm the potential for routine and significant dust‐cloud processing in DIBS cases, affecting both cloud properties and identifying a previously unidentified pathway for long‐range transport of dust.
Magnetic Fingerprints of Modern Sediments in the South China Sea Resulting From Source‐to‐Sink Processes
Authors: Kissel C. , Sarnthein M. , Laj C. , Wang P. X. , Wandres C. , Egli R. 
Published: June 2018

AbstractMore than 650 Mt/year of fluvial sediment are delivered from continental regions into the South China Sea (SCS). Previous studies have shown that the composition of the magnetic fraction of riverine sediments drained into the SCS is significantly variable from north to south. On the basis of this evidence, we now examine a full set of magnetic properties for a number of core tops taken at water depth of mostly between 800 and 3,500 m. Room temperature magnetic parameters and thermal spectra are used to obtain information about the concentration and mineralogical magnetic composition. Spatial changes are observed in the relative proportion of magnetite and hematite with an increase of the latter toward the south, similarly to the observation on land. However, the N‐S contrast is much weaker in marine core tops than in river sediments, because of the role played by the shelf in partly trapping river‐borne sediments, in particular in the southern SCS. In part, sediments also reach the continental slope and the deep basins, being transported and mixed by surface and deepwater currents, which yield the magnetite‐hematite mixing in the south. For the first time, we characterize a wide spectrum of magnetic properties of modern marine sediment in the SCS. Our results give important insights into the modern pathways of sediment particles, depicting the source‐to‐sink processes that affect the terrigenous sediment load.
Automatic Classification of Auroral Images From the Oslo Auroral THEMIS (OATH) Data Set Using Machine Learning
Authors: Clausen Lasse B. N. , Nickisch Hannes 
Published: June 2018

AbstractBased on their salient features we manually label 5,824 images from various Time History of Events and Macroscale Interactions during Substorms (THEMIS) all‐sky imagers; the labels we use are clear/no aurora, cloudy, moon, arc, diffuse, and discrete. We then use a pretrained deep neural network to automatically extract a 1,001‐dimensional feature vector from these images. Together, the labels and feature vectors are used to train a ridge classifier that is then able to correctly predict the category of unseen auroral images based on extracted features with 82% accuracy. If we only distinguish between a binary classification aurora and no aurora, the true positive rate increases to 96%. While this study paves the way for easy automatic classification of all auroral images from the THEMIS all‐sky imager chain, we believe that the methodology shown here is readily applied to all images from any other auroral imager as long as the data are available in digital form. Both the neural network and the ridge classifier are free, off‐the‐shelf computer codes; the simplicity of our approach is demonstrated by the fact that our entire analysis comprises about 50 lines of Python code. Automatically attaching labels to all available all‐sky imager data would enable statistical studies of unprecedented scope.