bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic reflection imaging of the Juan de Fuca plate from ridge to trench: New constraints on the distribution of faulting and evolution of the crust prior to subduction
Authors: Han Shuoshuo , Carbotte Suzanne M. , Canales Juan Pablo , Nedimović Mladen R. , Carton Hélène , Gibson James C. , Horning Greg W. 
Published: February 2016

AbstractWe present prestack time‐migrated multichannel seismic images along two cross‐plate transects from the Juan de Fuca (JdF) Ridge to the Cascadia deformation front (DF) offshore Oregon and Washington from which we characterize crustal structure, distribution and extent of faults across the plate interior as the crust ages and near the DF in response to subduction bending. Within the plate interior, we observe numerous small offset faults in the sediment section beginning 50–70 km from the ridge axis with sparse fault plane reflections confined to the upper crust. Plate bending due to sediment loading and subduction initiates at ~120–150 km and ~65–80 km seaward of the DF, respectively, and is accompanied by increase in sediment fault offsets and enhancement of deeper fault plane reflectivity. Most bend faulting deformation occurs within 40 km from the DF; on the Oregon transect, bright fault plane reflections that extend through the crust and 6–7 km into the mantle are observed. If attributed to serpentinization, ~0.12–0.92 wt % water within the uppermost 6 km of the mantle is estimated. On the Washington transect, bending faults are confined to the sediment section and upper‐middle crust. The regional difference in subduction bend‐faulting and potential hydration of the JdF plate is inconsistent with the spatial distribution of intermediate‐depth intraslab seismicity at Cascadia. A series of distinctive, ridgeward dipping (20°–40°) lower crustal reflections are imaged in ~6–8 Ma crust along both transects and are interpreted as ductile shear zones formed within the ridge's accretionary zone in response to temporal variations in mantle upwelling, possibly associated with previously recognized plate reorganizations at 8.5 Ma and 5.9 Ma.
Atmospheric ionization by high‐fluence, hard‐spectrum solar proton events and their probable appearance in the ice core archive
Authors: Melott Adrian L. , Thomas Brian C. , Laird Claude M. , Neuenswander Ben , Atri Dimitra 
Published: February 2016

AbstractSolar energetic particles ionize the atmosphere, leading to production of nitrogen oxides. It has been suggested that some such events are visible as layers of nitrate in ice cores, yielding archives of energetic, high‐fluence solar proton events (SPEs). This has been controversial, due to slowness of transport for these species down from the upper stratosphere; past numerical simulations based on an analytic calculation have shown very little ionization below the midstratosphere. These simulations suffer from deficiencies: they consider only soft SPEs and narrow energy ranges; spectral fits are poorly chosen; and with few exceptions secondary particles in air showers are ignored. Using improved simulations that follow development of the proton‐induced air shower, we find consistency with recent experiments showing substantial excess ionization down to 5 km. We compute nitrate available from the 23 February 1956 SPE, which had a high‐fluence, hard‐spectrum, and well‐resolved associated nitrate peak in a Greenland ice core. For the first time, we find that this event can account for ice core data with timely (~2 months) transport downward between 46 km and the surface, thus indicating an archive of high‐fluence, hard‐spectrum SPEs covering the last several millennia. We discuss interpretations of this result, as well as the lack of a clearly defined nitrate spike associated with the soft‐spectrum 3–4 August 1972 SPE. We suggest that hard‐spectrum SPEs, especially in the 6 months of polar winter, are detectable in ice cores and that more work needs to be done to investigate this.
Sensitivity of thin cirrus clouds in the tropical tropopause layer to ice crystal shape and radiative absorption
Authors: Russotto R. D. , Ackerman T. P. , Durran D. R. 
Published: February 2016

AbstractSubvisible cirrus clouds in the tropical tropopause layer (TTL) play potentially important roles in Earth's radiation budget and in the transport of water into the stratosphere. Previous work on these clouds with 2‐D cloud‐resolving models has assumed that all ice crystals were spherical, producing too few crystals greater than 60 μm in length compared with observations. In this study, the System for Atmospheric Modeling cloud‐resolving model is modified in order to calculate the fall speeds, growth rates, and radiative absorption of nonspherical ice crystals. This extended model is used in simulations that aim to provide an upper bound on the effects of ice crystal shape on the time evolution of thin cirrus clouds and to identify the physical processes responsible for any such effects. Model runs assuming spheroidal crystals result in a higher center of cloud ice mass than in the control, spherical case, while the total mass of ice is little affected by the shape. Increasing the radiative heating results in less total cloud ice mass relative to the control case, an effect which is robust with more extreme perturbations to the absorption coefficients. This is due to higher temperatures reducing the relative humidity in the cloud and its environment, and greater entrainment of dry air due to dynamical changes. Comparisons of modeled ice crystal size distributions with recent airborne observations of TTL cirrus show that incorporating nonspherical shape has the potential to bring the model closer to observations.
Controls on and effects of armoring and vertical sorting in aeolian dune fields: A numerical simulation study
Authors: Gao Xin , Narteau Clément , Rozier Olivier 
Published: February 2016

AbstractUnlike ripples, there are only few numerical studies on grain size segregation at the scale of dunes in aeolian environments. Here we use a cellular automaton model to analyze vertical sorting in granular mixtures under steady unidirectional flow conditions. We investigate the feedbacks between dune growth and the segregation mechanisms by varying the size of coarse grains and their proportion within the bed. We systematically observe the development of a horizontal layer of coarse grains at the top of which sorted bed forms may grow by amalgamation. The formation of such an armor layer controls the overall sediment transport and availability. The emergence of dunes and the transition from barchan to transverse dune fields depend only on the grain size distribution of the initial sediment layer. As confirmed by observation, this result indicates that armor layers should be present in most arid deserts, where they are likely to control dune morphodynamics.
Basic Principles of Inverse Problems for Optical Scientists
Authors: Anastasio Mark A. , Schoonover Robert W. 
Published: February 2016

AbstractModern optical imaging systems are complicated in nature and require solution of a mathematical inverse problem for image formation. In this article, we provide an overview of some basic concepts and mathematical descriptions of linear inverse problems. This includes a review of linear vector spaces, Hilbert spaces, and operators. The singular value decomposition (SVD) is reviewed as a tool to analyze imaging system models. Methods for finding solutions to the inverse problem for discrete systems are subsequently provided, as well as a specific example from differential phase contrast tomography.
Robust switched control based on strictly positive real systems and variable structure control techniques
Authors: Cardim Rodrigo , Teixeira Marcelo C. M. , Assunção Edvaldo , Ribeiro Jean M. S. , Covacic Márcio R. , Gaino Ruberlei 
Published: February 2016

SummaryThis paper is concerned with the design of variable structure controllers for uncertain switched linear plants. The proposed method is based on Lyapunov–Metzler inequalities and on properties of strictly positive real (SPR) systems, with the advantage that it can be applied in control of uncertain switched linear system. The first contribution shows that there exists a solution of the SPR synthesis for a class of linear uncertain switched systems using switched static output feedback, if and only if there exists a solution of this SPR synthesis with switched static state feedback. This result is a generalization of known conditions regarding this problem, for linear time‐invariant and known (without uncertainties) plants, and offers a possible procedure for output feedback SPR synthesis: first solve the state feedback SPR synthesis and then, using the obtained solution, find a solution for the output feedback SPR synthesis. Next are presented necessary and sufficient (sufficient) conditions for the SPR synthesis for a class of linear uncertain switched systems using switched static output feedback, for plants with the same number of inputs and outputs (with the number of outputs greater than the number of inputs). Two examples illustrate the effectiveness of the robust control system, including applications of the proposed methods, considering switched static state feedback and switched static output feedback, in the design of switching control strategies for active suspensions systems in road vehicles. Performance indices such as decay rate, guaranteed cost, and restriction in the norm of controller gains are considered in these designs. Copyright © 2016 John Wiley & Sons, Ltd.
A three‐dimensional geometric morphometrics view of the cranial shape variation and population history in the New World
Authors: Galland Manon , Friess Martin 
Published: February 2016

ObjectivesCraniofacial variation in past and present Amerindians has been attributed to the effect of multiple founder events, or to one major migration followed byin situdifferentiation and possibly recurrent contacts among Circum‐Arctic groups. Our study aims to: (i) detect morphological differences that may indicate several migrations; (ii) test for the presence of genetic isolation; and (iii) test the correlation between shape data and competing settlement hypotheses by taking into account geography, chronology, climate effects, the presence of genetic isolation and recurrent gene flow.MethodsWe analyzed a large sample of three‐dimensional (3D) cranial surface scans (803 specimens) including past and modern groups from America and Australasia. Shape variation was investigated using geometric morphometrics. Differential external gene flow was evaluated by applying genetic concepts to morphometric data (Relethford‐Blangero approach). Settlement hypotheses were tested using a matrix correlation approach (Mantel tests).ResultsOur results highlight the strong dichotomy between Circum‐Arctic and continental Amerindians as well as the impact of climate adaptation, and possibly recurrent gene flow in the Circum‐Arctic area. There is also evidence for the impact of genetic isolation on phenetic variation in Baja California. Several settlement hypotheses are correlated with our data.ConclusionsThe three approaches used in this study highlight the importance of local processes especially in Baja California, and caution against the use of overly simplistic models when searching for the number of migration events. The results stress the complexity of the settlement of the Americas as well as the mosaic nature of the processes involved in this process. Am. J. Hum. Biol. 28:646–661, 2016. © 2016 Wiley Periodicals, Inc.
Der Einfluss des nacnac‐Liganden in der Eisen(I)‐vermittelten P4‐Umwandlung
Authors: Spitzer Fabian , Graßl Christian , Balázs Gábor , Zolnhofer Eva M. , Meyer Karsten , Scheer Manfred 
Published: February 2016

AbstractEine Studie zur P4‐Umwandlung an niedervalenten Eisenkomplexen wird vorgestellt, bei der β‐Diketiminato(L)‐FeI‐Komplexe vom Typ [LFe(tol)] (tol=Toluol; L=L1 (1 a), L2 (1 b), L3 (1 c)) mit unterschiedlichen Kombinationen von aromatischen und Rückgrat‐Substituenten am Liganden genutzt werden. Die Produkte [(LFe)4(μ4‐η2:η2:η2:η2‐P8)] (L=L1 (2 a), L2 (2 b)), die ein P8‐Gerüst enthalten, werden durch die Reaktion von 1 a,b mit P4 in Toluol bei Raumtemperatur erhalten. Bei Verwendung eines etwas sperrigeren Liganden in 1 c wird [(L3Fe)2(μ‐η4:η4‐P4)] (2 c) gebildet, welches eine cyclo‐P4‐Einheit enthält. Die Verbindungen 2 a–c wurden umfassend charakterisiert und ihre elektronische Struktur durch SQUID‐Magnetisierung und 57Fe‐Mössbauer‐Spektroskopie sowie mittels DFT‐Methoden untersucht.
Total Synthesis of (−)‐Nakadomarin A
Authors: Clark J. Stephen , Xu Chao 
Published: February 2016

AbstractA highly efficient 12‐step synthesis of the marine alkaloid (−)‐nakadomarin A has been accomplished. The key advanced intermediate, a tetracyclic ketone derivative, was constructed in just seven steps using a sequence that includes an asymmetric Pauson–Khand reaction, an Overman rearrangement reaction, a ring‐closing metathesis reaction, and an amination reaction. Late introduction of the furan ring during the synthesis of (−)‐nakadomarin A means that the key tetracyclic ketone derivative has the potential to serve as an advanced intermediate for the synthesis of related marine alkaloids.
An integrated numerical study of coextrusion flow inside and outside the die
Authors: Yang Chuan , Li Ziran 
Published: February 2016

ABSTRACTThe three‐dimensional coextrusion flow of two polymer melts is solved over the die‐extrudate region using the finite element method. As elastic recovery is known to be the main source of extrudate swelling, a viscoelastic constitutive model (the Phan‐Thien‐Tanner or PTT model) is adopted to characterize the rheological behavior of the elastomers. A major challenge in the simulation of multilayer flow inside and outside the die is to update multiple moving surfaces (material interface and extrudate free surface) simultaneously. This difficulty is resolved by introducing a two‐step updating algorithm which decouples the iterations of the interface and the free surface. The effects of extrudate swelling and bending on interface deformation are investigated herein, together with the interface shape dependency on flow elasticity. The numerical method is also applied to an industrial profile and the simulation result is in quantitative agreement with the experimental coextrusion data. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43522.
Chemical Composition and Antimicrobial Activity of the Essential Oil and Methanol Extract of Hypericum aegypticum subsp. webbii (Spach) N. Robson
Authors: Marčetić Mirjana D. , Milenković Marina T. , Lakušić Dmitar V. , Lakušić Branislava S. 
Published: February 2016

Hypericum aegypticum subsp. webbii is an evergreen shrub spread in Mediterranean part of central and southeastern Europe. The chemical composition and antimicrobial activity of the essential oil and MeOH extract of H. aegypticum subsp. webbii were investigated. The monoterpenes α‐pinene (63.4 – 68.5%) and β‐pinene (16.9 – 17.0%) were main compounds in the volatile oil from aerial parts. In the cluster analysis, the essential oil of H. aegypticum subsp. webbii was separated and chemically different from the oil of other subspecies of H. aegypticum as well as other Hypericum species from Greece. SIMPER analysis revealed that α‐pinene (24.79%) was the component that contributed the most to differences between all oils. Also, there was extremely high overall dissimilarity between three subspecies of H. aegypticum. MeOH extract of aerial parts of H. aegypticum subsp. webbii contained flavonoids rutin (56.4 ± 0.9 mg/g), hyperoside and quercetin, and phenolic acids chlorogenic and caffeic acid, while naphthodianthrones were not detected. The antimicrobial activity of essential oil was moderate (MIC from 100 to >200 μg/ml), while MeOH extract inhibited the growth of Gram‐positive bacteria Bacillus subtilis, Enterococcus faecalis, Staphylococcus epidermidis, and Micrococcus luteus (MIC 50 – 100 μg/ml), more pronounced than the extract of H. perforatum (MIC 200 – >200 μg/ml).
Computational Fluid Dynamics Simulation of Multiscale Mixing in Anionic Polymerization Tubular Reactors
Authors: Xie Le , Zhu Li‐Tao , Luo Zheng‐Hong 
Published: February 2016

AbstractThe molecular properties of polymers are greatly influenced by operation parameters during polymerization in reactors. Since operation parameter distributions in reactors also result in molecular property distributions, polymerization bridges the gap between molecular properties and operation parameters. The combination of the computational fluid dynamics technology with the method of moments to form a uniquely coupled model was used to describe multiscale mixing fields in the reactor. The coupled model was validated by open experimental data, and the effects of polymerization kinetics on macroscopic and microscopic fields were investigated numerically. Also, the coupled model was applied to numerically predict the impacts of some key operation conditions on the main macroscopic flow field parameters and polymer molecular properties.
Solvent‐Aided Layer Crystallization of Glycerol – Post‐Treatment and the Influence of Agitation
Authors: Eisenbart Felix J. , Ulrich Joachim 
Published: February 2016

AbstractThe purification of glycerol from water by melt layer crystallization with an additional solvent to influence the crystallization kinetics is investigated. Static cold finger experiments including a sweating‐like post‐treatment were carried out. A simple seeding technique is introduced to facilitate layer crystallization without primary nucleation or agitation. It is shown that the glycerol crystal layers tend to burst in a traditional sweating procedure, but a modified temperature profile allows a post‐treatment with a similar effect. The solvent improved the separation efficiency of the growth step and also the one of the sweating step. Therefore, its effect does not only result from its influence on forced convection but also that on natural convection and diffusion.
Boyer's Reaction and Transetherification: Mechanism and New Perspectives
Authors: Fraschetti Caterina , Speranza Maurizio , Guarcini Laura , Roselli Graziella , Filippi Antonello 
Published: February 2016

AbstractThe progress and stereochemistry of Boyer's reaction were analyzed using several simple, chiral, alcoholic substrates, a variable amount of BiBr3 and different solvents. Basic solvents inhibit the reaction, while cyclohexane works very well; thus, it was our choice for the present study. In contrast to previous works, BiBr3 behaves as a true catalyst, being not consumed during the reaction. Although poisoning of the catalyst occurs to some extent, it does not prejudice the reaction yields (>90%). Gas chromatography/mass spectrometry (GC–MS) monitoring of the reaction revealed that, for example, in the presence of alcohol rac-1, isomeric ethers 4 transetherificate to 3. We propose a unifying mechanistic model for both Boyer's and transetherification reactions, in which the electronic properties of n‐adducts intermediates, formed by combination of bismuth(III) of BiBr3 and oxygen atoms of alcohols and ethers, play the key role for both the reactivity and the stereochemical outcome of the reaction. Chirality 28:269–275, 2016. © 2016 Wiley Periodicals, Inc.
Reliability of Orientational Order Parameters Determined from Two‐dimensional X‐ray Diffraction Patterns: A Simulation Study
Authors: Jenz Frank , Jagiella Stefan , Glaser Matthew A. , Giesselmann Frank 
Published: February 2016

AbstractThe orientational order parameter
is one of the most important quantities to describe the degree of long‐range orientational ordering of liquid crystals. There are several approaches to experimentally measure this order parameter of liquid crystalline phases but every method includes substantial simplifications and assumptions. We present a simulation‐based approach to elucidate the reliability of the method of Davidson, Petermann and Levelut to measure
via 2D X‐ray experiments. We have found that this method slightly underestimates
by an absolute value of only 0.05 and thus provides reliable measures of
by X‐ray diffraction.
Synthesis of ZnSnN2 crystals via a high‐pressure metathesis reaction
Authors: Kawamura F. , Yamada N. , Imai M. , Taniguchi T. 
Published: February 2016

The synthesis of crystals of a zinc‐ and tin‐based earth‐abundant element nitride (ZnSnN2) semiconductor was successfully achieved via a metathesis reaction under high pressure. Pressures exceeding 5.5 GPa were required to obtain single‐phase crystals. The material's bandgap was determined to be 1.4 eV, which is ideal for photovoltaic absorbers and visible light‐active photocatalysts. The decomposition temperature of the material was estimated to be approximately 350‒400 °C at atmospheric pressure. Finally, the chemical stability of the material against alkali and acid solutions was sufficient for photovoltaic and photocatalytic applications.
An anonymous and provably secure authentication scheme for mobile user
Authors: Islam SK Hafizul , Obaidat Mohammad S. , Amin Ruhul 
Published: February 2016

SummaryChebyshev chaotic map is an important tool used in the domain of cryptography to develop different schemes for numerous applications. In 2014, Lin put forwarded a mobile user authentication system using dynamic identity and chaotic map. Lin declared that the scheme offers mutual authentication and session key agreement between user and server. Moreover, they stated that the scheme offers user anonymity and resilience against known attacks. However, we carefully examined Lin's scheme and found that it is no longer usable for practical applications as (i) it has no facility to identify the wrong password and identity, which are inputted by the user during login and password update phases, (ii) it has no facility to protect user impersonation attack, and (iii) it has the problem of session key forward secrecy. We put forwarded an enhanced scheme based on extended chaotic map to repair the fragilities of Lin's scheme. We formally examined the security of our scheme and demonstrated that it is provably secured in random oracle model. Further, we presented some informal cryptanalysis to make sure that the enhanced scheme is secure from known attacks. Our scheme is also computation efficient against other competitive protocols. Copyright © 2016 John Wiley & Sons, Ltd.