bluuebunny/crossref_metadata_2025 huggingface dataset:
The Calderón problem in transversally anisotropic geometries
Authors: Dos Santos Ferreira David , Kurylev Yaroslav , Lassas Matti , Salo Mikko
Published: October 2016

We consider the anisotropic Calderón problem of recovering a conductivity matrix or a Riemannian metric from electrical boundary measurements in three and higher dimensions. In the earlier work [14], it was shown that a metric in a fixed conformal class is uniquely determined by boundary measurements under two conditions: (1) the metric is conformally transversally anisotropic (CTA), and (2) the transversal manifold is simple. In this paper we will consider geometries satisfying (1) but not (2). The first main result states that the boundary measurements uniquely determine a mixed Fourier transform/attenuated geodesic ray transform (or integral against a more general semiclassical limit measure) of an unknown coefficient. In particular, one obtains uniqueness results whenever the geodesic ray transform on the transversal manifold is injective. The second result shows that the boundary measurements in an infinite cylinder uniquely determine the transversal metric. The first result is proved by using complex geometrical optics solutions involving Gaussian beam quasimodes, and the second result follows from a connection between the Calderón problem and Gel’fand’s inverse problem for the wave equation and the boundary control method.
Runge-Kutta Discontinuous Galerkin Method with Front Tracking Method for Solving the Compressible Two-Medium Flow on Unstructured Meshes
Authors: Lu Haitian , Zhu Jun , Wang Chunwu , Zhao Ning
Published: October 2016

In this paper, we extend using the Runge-Kutta discontinuous Galerkin method together with the front tracking method to simulate the compressible two-medium flow on unstructured meshes. A Riemann problem is constructed in the normal direction in the material interfacial region, with the goal of obtaining a compact, robust and efficient procedure to track the explicit sharp interface precisely. Extensive numerical tests including the gas-gas and gas-liquid flows are provided to show the proposed methodologies possess the capability of enhancing the resolutions nearby the discontinuities inside of the single medium flow and the interfacial vicinities of the two-medium flow in many occasions.
XFEM for Fracture Analysis in 2D Anisotropic Elasticity
Authors: Jia Honggang , Nie Yufeng , Li Junlin
Published: October 2016

In this paper, a method is proposed for extracting fracture parameters in anisotropic thermoelasticity cracking via interaction integral method within the framework of extended finite element method (XFEM). The proposed method is applied to linear thermoelastic crack problems. The numerical results of the stress intensity factors (SIFs) are presented and compared with those reported in related references. The good agreement of the results obtained by the developed method with those obtained by other numerical solutions proves the applicability of the proposed approach and confirms its capability of efficiently extracting thermoelasticity fracture parameters in anisotropic materials.
Numerical Solution of Euler-Lagrange Equation with Caputo Derivatives
Authors: Blaszczyk Tomasz , Ciesielski Mariusz
Published: October 2016

In this paper the fractional Euler-Lagrange equation is considered. The fractional equation with the left and right Caputo derivatives of orderα∈ (0,1] is transformed into its corresponding integral form. Next, we present a numerical solution of the integral form of the considered equation. On the basis of numerical results, the convergence of the proposed method is determined. Examples of numerical solutions of this equation are shown in the final part of this paper.
Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling
Authors: Heinze Christoph , Hoogakker Babette A. A. , Winguth Arne
Published: October 2016

Abstract. What role did changes in marine carbon cycle processes and calcareous organisms play in glacial–interglacial variation in atmospheric pCO2? In order to answer this question, we explore results from an ocean biogeochemical general circulation model. We attempt to systematically reconcile model results with time-dependent sediment core data from the observations. For this purpose, we fit simulated sensitivities of oceanic tracer concentrations to changes in governing carbon cycle parameters to measured sediment core data. We assume that the time variation in the governing carbon cycle parameters follows the general pattern of the glacial–interglacial deuterium anomaly. Our analysis provides an independent estimate of a maximum mean sea surface temperature drawdown of about 5 °C and a maximum outgassing of the land biosphere by about 430 Pg C at the Last Glacial Maximum as compared to pre-industrial times. The overall fit of modelled palaeoclimate tracers to observations, however, remains quite weak, indicating the potential of more detailed modelling studies to fully exploit the information stored in the palaeoclimatic archive. This study confirms the hypothesis that a decline in ocean temperature and a more efficient biological carbon pump in combination with changes in ocean circulation are the key factors for explaining the glacial CO2 drawdown. The analysis suggests that potential changes in the export rain ratio POC : CaCO3 may not have a substantial imprint on the palaeoclimatic archive. The use of the last glacial as an inverted analogue to potential ocean acidification impacts thus may be quite limited. A strong decrease in CaCO3 export production could potentially contribute to the glacial CO2 decline in the atmosphere, but this remains hypothetical.
Development of a winter wheat model in the Community Land Model
(version 4.5)
Authors: Lu Yaqiong , Williams Ian N. , Bagley Justin E. , Torn Margaret S. , Kueppers Lara M.
Published: October 2016

Abstract. Winter wheat is a staple crop for global food security, and is the dominant vegetation cover for a significant fraction of earth's croplands. As such, it plays an important role in carbon cycling and land-atmosphere interactions in these key regions. Accurate simulation of winter wheat growth is not only crucial for future yield prediction under changing climate, but also for understanding the energy and water cycles for winter wheat dominated regions. We developed a new winter wheat model in the Community Land Model (CLM) to better simulate wheat growth and grain production. These included schemes to represent vernalization, as well as frost tolerance and damage. We calibrated three key parameters (minimum planting temperature, maximum crop growth days, and initial value of leaf carbon allocation coefficient) and modified the grain carbon allocation algorithm for simulations at the U.S. Southern Great Plains ARM site (US-ARM), and validated the model performance at three additional sites across the continental US. We found that the new winter wheat model improved the prediction of monthly variation in leaf area index, latent heat flux, and net ecosystem exchange during the spring growing season. The model accurately simulated the interannual variation in yield at the US-ARM site, but underestimated yield at sites and in regions (Northwestern and Southeastern US) with historically greater yields.
Equilibrium absorptive partitioning theory between multiple aerosol particle modes
Authors: Crooks Matthew , Connolly Paul , Topping David , McFiggans Gordon
Published: October 2016

Abstract. An existing equilibrium absorptive partitioning model for calculating the equilibrium gas and particle concentrations of multiple semi-volatile organics within a bulk aerosol is extended to allow for multiple involatile aerosol modes of different sizes and chemical compositions. In the bulk aerosol problem, the partitioning coefficient determines the fraction of the total concentration of semi-volatile material that is in the condensed phase of the aerosol. This work modifies this definition for multiple polydisperse aerosol modes to account for multiple condensed concentrations, one for each semi-volatile on each involatile aerosol mode. The pivotal assumption in this work is that each aerosol mode contains an involatile constituent, thus overcoming the potential problem of smaller particles evaporating completely and then condensing on the larger particles to create a monodisperse aerosol at equilibrium. A parameterisation is proposed in which the coupled non-linear system of equations is approximated by a simpler set of equations obtained by setting the organic mole fraction in the partitioning coefficient to be the same across all modes. By perturbing the condensed masses about this approximate solution a correction term is derived that accounts for many of the removed complexities. This method offers a greatly increased efficiency in calculating the solution without significant loss in accuracy, thus making it suitable for inclusion in large-scale models.
Identification and Bioassay of Allelopathic Substances from Plant and Rhizosphere Soil Extracts of Adzuki Bean (Vigna angularis [Willd.] Ohwi & H. Ohashi.)
Authors: Song H. , Zhang P. P. , Gao X. L. , Xu S. X. , Zhou Q. , Feng B. L. , Fan Y. , Xie Y. P.
Published: October 2016

The soil sickness of Adzuki bean [Vigna angularis (Willd.) Ohwi & H. Ohashi] have been getting attention seriously under a continuously mono-cropping management-system in China. To investigate the allelopathy of rhizosphere soil and plant of Adzuki bean, culture dish and pot experiments were conducted. The compounds in the products were identified by High Performance Liquid Chromatography (HPLC).The aqueous extracts from rhizospheric soil and whole plant inhibited seed index (seed germination and seed potential) and plant growth under different degrees, and it showed concentration gradient effect on the inhibition of seed germination. Inhibition was stronger with increasment in extract concentration with the highest effect at 0.16 parts aqueous extract to 1 parts deionized water (0.16g·mL-1). The impact on growth varied among aqueous extracts from rhizospheric soil and the whole plant. Five phenolic compounds, cinnamic, phthalic, p-hydroxybenzoic, and isobutyricand glutaric acids, were detected from the rhizosphere soil and plant extract of Adzuki bean by HPLC method. Cinnamic, phthalic, and p-hydroxybenzoicacids were higher than that of the other phenolic acids. This result suggests that autotoxicity effects of phenolics on Adzuki bean probably happen in continuous mono-cropping systems.
Anaerobic fitness assessment in taekwondo athletes. A new perspective
Authors: Rocha Fernando , Louro Hugo , Matias Ricardo , Costa Aldo
Published: October 2016

We intended to determine the concurrent validity of a taekwondo specific anaerobic test (TSAT) to assess anaerobic fitness in taekwondo athletes. Seventeen elite male subjects (17.59 ± 4.34 years of age; 1.72 m ± .07 m in height; 61.3 kg ± 8.7 kg in weight and 15.6% ± 8.5% in body fat) performed a TSAT, which consisted of kicking a punching bag for 30 seconds. The standard test was the Wingate Anaerobic Test. Two trials were made for both tests and the agreement between both was tested. The variables analysed and compared were: peak power; relative peak power; mean anaerobic power; relative mean anaerobic power; fatigue index and anaerobic capacity. The number of kicks performed in the TSAT protocol and the maximum height of the counter movement jump (CMJ) were also registered. Trial I and II had significant ICC results in all variables (P = .000) ranged between 0.56 and 0.97. Both protocols were significantly correlated (r = 0.55 to 0.88; P = .000 to .05). CMJ strongly correlated with the number of techniques (r=0.59; P = .013) and the mean power (r = 0.56; P = .019) of the TSAT. The variables between the two methods correlate and are consistent, except for the anaerobic capacity that although correlated, is not consistent with constant bias, P = 0.001; CI]-705.1;-370.2[. TSAT has a level of agreement with the Wingate, and assigns specificity in the evaluation of these variables.

 
On the Simplicity of some Cuntz-Pimsner Algebras
Authors: Muhly Paul S. , Solel Baruch
Published: October 2016

Conditions are given on a $C^*$-correspondence $E$ over a $C^*$-algebra that guarantee that the associated Cuntz-Pimsner algebra $\mathscr{O} (E)$ is simple. Our findings generalize earlier results of Cuntz[5], Paschke [14], and Boyd, Keswani and Raeburn [2].
Exterior algebra resolutions arising from homogeneous bundles
Authors: Fløystad Gunnar
Published: October 2016

We describe resolutions of general maps (resp. general symmetric and skew-symmetric maps) $E^a \rightarrow E(1)^b$ given by linear forms over the exterior algebra $E$. Via the BGG-correspondence we describe the associated coherent sheaves. We also show how representation theory of algebraic groups enables one to solve these types of problems for much larger classes of maps.
Sufficient conditions for the Inversion Formula for the $k$-plane Radon Transform in $\mathsf R^n$
Authors: Jensen Sine R.
Published: October 2016

The inversion theorem (1) for the $k$-plane Radon transform in ${\mathsf R}^n$ is often stated for Schwartz functions, and lately for smooth functions on ${\mathsf R}^n$ fulfilling that $f(x)=O(|x|^{-N})$ for some $N>n$, cf. [6]. In this paper it will be shown, that it suffices to require that $f$ is locally Hölder continuous and $f(x)=O(|x|^{-N})$ for some $N>k$ ($N$ not necessarily an integer) in order for (1) to hold, and that the same decay on $f$ but $f$ only continuous implies an inversion formula only slightly weaker than (1).
A diagrammatic approach to link invariants of finite degree
Authors: Östlund Olof-Petter
Published: October 2016

In [5] M. Polyak and O. Viro developed a graphical calculus of diagrammatic formulas for Vassiliev link invariants, and presented several explicit formulas for low degree invariants. M. Goussarov [2] proved that this arrow diagram calculus provides formulas for all Vassiliev knot invariants. The original note [5] contained no proofs, and it also contained some minor inaccuracies. This paper fills the gap in literature by presenting the material of [5] with all proofs and details, in a self-contained form. Furthermore, a compatible coalgebra structure, related to the connected sum of knots, is introduced on the algebra of based arrow diagrams with one circle.
Local dynamics of uniformly quasiregular mappings
Authors: Hinkkanen Aimo , Martin Gaven J. , Mayer Volker
Published: October 2016

We investigate local dynamics of uniformly quasiregular mappings, give new examples and show in particular that there is no quasiconformal analogue of the Leau-Fatou linearization of parabolic dynamics.
On the determinacy of complex Jacobi matrices
Authors: Beckermann Bernhard , Smirnova Mirta Castro
Published: October 2016

The aim of this paper is to explore to which extend the theory of the Hamburger moment problem for real Jacobi matrices generalizes to the case of complex Jacobi matrices. In particular, we characterize the indeterminacy in terms of uniqueness of closed extensions of Jacobi matrices, and discuss the link to the growth of the smallest singular values of the underlying Hankel matrices. As a byproduct, we give a positive answer to the open question whether determinacy is preserved under bounded perturbations.
A remark on Poincaré inequalities on metric measure spaces
Authors: Keith Stephen , Rajala Kai
Published: October 2016

We show that, in a complete metric measure space equipped with a doubling Borel regular measure, the Poincaré inequality with upper gradients introduced by Heinonen and Koskela [3] is equivalent to the Poincaré inequality with "approximate Lipschitz constants" used by Semmes in [9].
Pointwise measurable functions
Authors: Render Herman , Rogge Lothar
Published: October 2016

We introduce the new concept of pointwise measurability. It is shown in this paper that a measurable function is measurable at each point and that for a large class of topological spaces the converse also holds. Moreover it can be seen that a function which is continuous at a point is Borel-measurable at this point too. Furthermore the set of measurability points is considered. If the range space is a $\sigma$-compact metric space, then this set is a $G_{\delta}$-set; if the range space is only a Polish space this is in general not true any longer.
Le Grand réveil acadien : une nouvelle mise en relief de la présence acadienne en Louisiane
Authors: Rabalais Nathan
Published: October 2016

En octobre 2015, le deuxième Grand réveil acadien (Gra) s’est déroulé à plusieurs endroits au sud de la Louisiane, commérant le 250e anniversaire de l’arrivée des Acadiens dans le territoire des Attakapas en 1765. Cet article présente les origines du Gra et les activités qui y ont eu lieu (musique, théâtre, ateliers de généalogie), en parallèle avec la première édition du Gra en 2011. L’événement est examiné dans une optique de mémoire collective et signale un contact accru entre la Louisiane et d’autres communautés francophones, notamment au Canada. Bien que le Gra puisse être vu comme le signe d’un intérêt renouvelé dans la promotion du français en Louisiane, cet événement reposerait sur un compromis entre la célébration d’une identité exclusivement acadienne et l’inclusion d’autres groupes francophones dans la Louisiane française et créole, un contexte très diversifié sur le plan culturel et ethnique.
La généalogie au service de l’histoire littéraire. Le cas de José Dubé dans Les Anciens Canadiens
Authors: Dubé Richard
Published: October 2016

La généalogie, passion partagée par de nombreux adeptes, a parfois reçu mauvaise presse. Un débat public a récemment opposé l’historien journaliste Jean-François Nadeau du Devoir à une quarantaine de spécialistes en histoire ou en généalogie. La position nuancée d’André Burguière, éclaire le débat : la généalogie n’est pas indispensable à l’historien, mais elle est utile à la science historique, dont elle partage les préoccupations de méthode. Au cours des années 1960, le généalogiste Raymond Dubé a recueilli une mine d’informations sur les Dubé d’Amérique et de France. Avec bonheur nous avons découvert sa correspondance avec Luc Lacoucière et, avec étonnement, nous avons appris que José Dubé des Anciens Canadiens de Philippe-Aubert de Gaspé est plus qu’un personnage de légende : c’est un être bien réel. La recherche généalogique confirme qu’il est un descendant de Marie Campion et de Mathurin Dubé, les ancêtres de la lignée des Dubé d’Amérique.
Ceintures fléchées : l’envers du décor
Authors: Genest-LeBlanc Monique
Published: October 2016

Faut-il révéler l’envers du décor qui corrige certains mythes et légendes, et faire connaître la vérité ? Ce que nous faisons dans notre étude de quelques cas. Érasme écrit en 1509 : « Les hommes ne veulent pas être dérangés dans leurs légendes et n’aiment pas qu’on change leur vérité. » Le jugement d’Érasme reste-t-il d’actualité ? Nous traitons ici des légendes écrites par Pierre Poulin en 1897 sur l’origine des ceintures fléchées ; de la ceinture d’Isaac Brock censée lui avoir été donnée par Tecumseh ; de la toile de Thielke, en 1838, des chefs hurons portant ceinture fléchée, laissant l’impression qu’ils en sont les auteurs ; d’une ceinture au Musée Pitt-Rivers en Angleterre rapportée du Canada et censée amérindienne des plaines de l’Ouest ; de l’écrit de Cécile Barot qui a porté à confusion en notant qu’on « tresse » les ceintures plutôt que les tisser. Nous constatons qu’on ne veut pas toujours accepter l’envers du décor.
Chronique du Centre de conservation du Québec
Authors: Champagne Nicole , Doyon Stéphane , Dendy Jean , O’Malley Michael
Published: October 2016

Pour cette première collaboration à Rabaska, la directrice du Centre de conservation du Québec (Ccq), Mme Nicole Champagne, nous présente cette institution exceptionnelle qui regroupe sous un même toit la plus importante équipe de professionnels de la conservation-restauration au Québec. Le Ccq nous offre ensuite trois textes préparés par des restaurateurs pour faire connaître des projets de restauration « coup de coeur » regroupés sous le thème de la chasse et la pêche. Stéphane Doyon, de l’atelier bois, relate une intervention menée sur le panneau polychrome « le mur de truites » ; Jean Dendy, restauratrice spécialisée en objets ethnologiques, raconte l’histoire d’une poire à poudre sculptée dans de l’os d’auroch ; enfin, Michael O’Malley, restaurateur de peintures, présente un aperçu des soins prodigués à un tableau présentant une « pêche miraculeuse ».
Capacitive response and room-temperature terahertz gain of a Wannier–Stark ladder system in GaAs-based superlattices
Authors: Naka Akiyoshi , Hirakawa Kazuhiko , Unuma Takeya
Published: October 2016

We investigate the phase and terahertz (THz) gain of Bloch oscillations in GaAs-based superlattices at various temperatures of T = 80–298 K by using THz emission spectroscopy under bias electric fields. The transient current is found to start from its maximum nearly as damped cos ωB
t (ωB/2π: Bloch frequency) throughout this temperature range, having only a small initial phase even for kT > ħωB (k: Boltzmann constant) and dephasing time shortening with increasing temperature. A spectral analysis indicates inversionless THz gain that originates from the capacitive nature of a Wannier–Stark ladder system with broadened energy levels at room temperature.
Effect of plasma-catalyst system on NO removal using M–Cu (M = Mn, Ce, Cr, Co, and Fe) catalysts
Authors: Wang Tao , Liu Han-Zi , Yang Bin , Sun Bao-Min , Xiao Hai-Ping , Zhang Yong-Sheng
Published: October 2016

A series of M–Cu (M = Mn, Ce, Cr, Co, and Fe) bimetal oxide catalysts combined with plasma were prepared for NO
x
removal at various temperatures. All catalysts combined with plasma exhibited excellent deNO
x
activity. The Mn–Cu catalyst showed the highest selective catalytic reduction (SCR) activity; the NO removal efficiency of the Mn–Cu catalyst could reach 90% at a gas temperature of 25 °C. E/N increased as gas temperature increased; the mean electron energy and the proportion of high-energy electrons also increased considerably, producing more active radicals. Without any catalyst, the increase in temperature inhibited NO removal owing to O3 consumption. As the temperature increased, NO removal efficiency decreased below 100 °C; however, it increased in the range of 100–300 °C, and then decreased above 300 °C in the plasma-catalyst system. NO2 concentration decreased markedly at 150 °C via the fast SCR reaction.
Interpolation of 2‐D vector data using constraints from elasticity
Authors: Sandwell David T. , Wessel Paul
Published: October 2016

We present a method for interpolation of sparse two‐dimensional vector data. The method is based on the Green's functions of an elastic body subjected to in‐plane forces. This approach ensures elastic coupling between the two components of the interpolation. Users may adjust the coupling by varying Poisson's ratio. Smoothing can be achieved by ignoring the smallest eigenvalues in the matrix solution for the strengths of the unknown body forces. We demonstrate the method using irregularly distributed GPS velocities from southern California. Our technique has been implemented in both the Generic Mapping Tools and MATLAB®.
Geologic influence on groundwater salinity drives large seawater circulation through the continental shelf
Authors: Michael Holly A. , Scott Kaileigh C. , Koneshloo Mohammad , Yu Xuan , Khan Mahfuzur R. , Li Katie
Published: October 2016

Observations of offshore freshened groundwater and saline groundwater discharge along continental shelves have important implications for water resources, ecosystem function, and the composition of the ocean, but they cannot be explained by basic theory. We show that these independent observations are linked and result from processes that drive variable‐density groundwater flow through the spatial heterogeneity that is ubiquitous in geologic formations. We use lithologic data to develop geostatistical models that mimic the architecture of coastal aquifers. Simulation of groundwater flow and salt transport through these random realizations shows that heterogeneity produces spatially complex subsurface salinity distributions that extend tens of kilometers offshore, even at steady state. The associated density gradients drive high saline groundwater circulation rates that cannot be predicted by equivalent homogeneous models. Results suggest that these phenomena may be common along continental shelves, potentially altering estimates of ocean chemical budgets and impacting coastal water management for future generations.
Global linkages originating from decadal oceanic variability in the subpolar North Atlantic
Authors: Chafik L. , Häkkinen S. , England M. H. , Carton J. A. , Nigam S. , Ruiz‐Barradas A. , Hannachi A. , Miller L.
Published: October 2016

The anomalous decadal warming of the subpolar North Atlantic Ocean (SPNA), and the northward spreading of this warm water, has been linked to rapid Arctic sea ice loss and more frequent cold European winters. Recently, variations in this heat transport have also been reported to covary with global warming slowdown/acceleration periods via a Pacific climate response. We here examine the role of SPNA temperature variability in this Atlantic‐Pacific climate connectivity. We find that the evolution of ocean heat content anomalies from the subtropics to the subpolar region, likely due to ocean circulation changes, coincides with a basin‐wide Atlantic warming/cooling. This induces an Atlantic‐Pacific sea surface temperature seesaw, which in turn, strengthens/weakens the Walker circulation and amplifies the Pacific decadal variability that triggers pronounced global‐scale atmospheric circulation anomalies. We conclude that the decadal oceanic variability in the SPNA is an essential component of the tropical interactions between the Atlantic and Pacific Oceans.
Proton temperature relaxation in the solar wind by combined collective and collisional processes
Authors: Yoon Peter H.
Published: October 2016

It is well established that various plasma instabilities regulate the proton temperature anisotropy in the solar wind. However, the question of why majority of data in
phase space are broadly distributed near isotropic conditions has not been successfully addressed. Among possible causes are local perpendicular heating, binary collisions, and geometrical effects. The present paper examines the influence of binary collisions, based upon recently formulated collisional transport theory for magnetized plasmas combined with macroscopic quasilinear theory for proton cyclotron and parallel firehose instabilities. The spatial development of perpendicular and parallel temperatures for protons as well as spatial distribution of excited wave magnetic field energy density are studied by making use of model solar wind. The present finding suggests that binary collisions may contribute toward the isotropization process but does not completely explain the isotropization.
Temporal models for the episodic volcanism of Campi Flegrei caldera (Italy) with uncertainty quantification
Authors: Bevilacqua Andrea , Flandoli Franco , Neri Augusto , Isaia Roberto , Vitale Stefano
Published: October 2016

After the large‐scale event of Neapolitan Yellow Tuff (~15 ka B.P.), intense and mostly explosive volcanism has occurred within and along the boundaries of the Campi Flegrei caldera (Italy). Eruptions occurred closely spaced in time, over periods from a few centuries to a few millennia, and were alternated with periods of quiescence lasting up to several millennia. Often events also occurred closely in space, thus generating a cluster of events. This study had two main objectives: (1) to describe the uncertainty in the geologic record by using a quantitative model and (2) to develop, based on the uncertainty assessment, a long‐term subdomain specific temporal probability model that describes the temporal and spatial eruptive behavior of the caldera. In particular, the study adopts a space‐time doubly stochastic nonhomogeneous Poisson‐type model with a local self‐excitation feature able to generate clustering of events which are consistent with the reconstructed record of Campi Flegrei. Results allow the evaluation of similarities and differences between the three epochs of activity as well as to derive eruptive base rate of the caldera and its capacity to generate clusters of events. The temporal probability model is also used to investigate the effect of the most recent eruption of Monte Nuovo (A.D. 1538) in a possible reactivation of the caldera and to estimate the time to the next eruption under different volcanological and modeling assumptions.
CMIP5 earth system models with biogeochemistry: An assessment for the southwest Pacific Ocean
Authors: Rickard Graham J. , Behrens Erik , Chiswell Stephen M.
Published: October 2016

An assessment is made of the ability of CMIP5 models to represent the seasonal biogeochemical cycles over the late twentieth century in the southwest Pacific Ocean. In particular, sea surface temperature (SST), surface chlorophyll a, nitrate, phosphate, silicate, and the depth of the seasonal thermocline, are examined to quantify the physical‐biogeochemical capabilities of each model; the result is a “ranking” estimate enabling model ensemble generation. The better/less ranked ensembles we refer to as inner/outer, respectively. The ensembles then allow less well‐observed variables such as iron and vertically integrated primary production to be assessed. The assessment establishes model output confidence limits for setting bounds on future model scenario ecosystem change projections. By the end of the twenty first century under Representative Concentration Pathways (RCP) RCP4.5 and/or RCP8.5, our best estimates suggest that there will be average domain wide increases in SST and surface iron, but average decreases in surface chlorophyll a, nitrate, and phosphate, accompanied by relatively large decreases in the depth of the seasonal thermocline (all changes realized by both ensembles). On the other hand, for surface silicate the inner ensemble suggests general declines, and vice versa for the outer ensemble. For integrated primary production, the ensembles predict declines in subtropical water, but elsewhere generally less significant changes.
Physicochemical characteristics of black carbon aerosol and its radiative impact in a polluted urban area of China
Authors: Wang Qiyuan , Huang Ru‐Jin , Zhao Zhuzi , Cao Junji , Ni Haiyan , Tie Xuexi , Zhao Shuyu , Su Xiaoli , Han Yongming , Shen Zhenxing , Wang Yichen , Zhang Ningning , Zhou Yaqing , Corbin Joel C.
Published: October 2016

Black carbon (BC) aerosol plays an important role in the Earth's radiative balance. An intensive measurement campaign was conducted at Xi'an, China, from December 2012 to January 2013 to investigate the sources and physicochemical characteristics of refractory BC (rBC) and its direct radiative forcing at the surface. The overall average rBC concentration for the campaign was 8.0 ± 7.1 µg m−3. Source apportionment based on positive matrix factorization showed that traffic was the dominant rBC source (46.0%), followed by coal burning (33.9%) and biomass burning (20.1%). The rBC mass size distributions were monomodal and lognormal with larger mass median diameters for coal burning source (215 nm) compared with the traffic source (189 nm). Coal burning rBC was more strongly associated with sulfate than traffic rBC, suggesting a higher cloud condensation nuclei activity. The slope of a robust linear regression between rBC and carbon monoxide (CO) for all samples was 5.9 µg m−3 ppm−1, and the slope for the coal burning source (4.5 µg m−3 ppm−1) was larger than that for the traffic source (2.7 µg m−3 ppm−1). The net rBC emission during winter of 2009 was estimated to be 4.5 Gg based on the relationship between rBC and CO. A Tropospheric Ultraviolet and Visible radiation model showed that the average daytime value for the clear‐sky direct radiative forcing due to rBC from 23 December 2012 to 31 January 2013 was −47.7 ± 28.9 W m−2, which amounted to an average of 45.7% of the total surface atmospheric aerosol forcing.
Modulations of aerosol impacts on cloud microphysics induced by the warm Kuroshio Current under the East Asian winter monsoon
Authors: Koike M. , Asano N. , Nakamura H. , Sakai S. , Nagao T. M. , Nakajima T. Y.
Published: October 2016

In our previous aircraft observations, the possible influence of high sea surface temperature (SST) along the Kuroshio Current on aerosol‐cloud interactions over the western North Pacific was revealed. The cloud droplet number concentration (Nc) was found to increase with decreasing near‐surface static stability (NSS), which was evaluated locally as the difference between the SST and surface air temperature (SAT). To explore the spatial and temporal extent to which this warm SST influence can be operative, the present study analyzed Nc values estimated from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite measurements. The comparison of the local Nc values between the high and low SST − SAT days revealed a marked increase in Nc (up to a factor of 1.8) along the Kuroshio Current in the southern East China Sea, where particularly high SST − SAT values (up to 8 K) were observed in winter under monsoonal cold air outflows from the Asian Continent. This cold airflow destabilizes the atmospheric boundary layer, which leads to enhanced updraft velocities within the well‐developed mixed layer and thus greater Nc. The monsoonal northwesterlies also bring a large amount of anthropogenic aerosols from the Asian continent that increase Nc in the first place. These results suggest that the same modulations of cloud microphysics can occur over other warm western boundary currents, including the Gulf Stream, under polluted cool continental airflows. Possibilities of influencing the cloud liquid water path are also discussed.
Isotopic ordering in atmospheric O2 as a tracer of ozone photochemistry and the tropical atmosphere
Authors: Yeung Laurence Y. , Murray Lee T. , Ash Jeanine L. , Young Edward D. , Boering Kristie A. , Atlas Elliot L. , Schauffler Sue M. , Lueb Richard A. , Langenfelds Ray L. , Krummel Paul. B. , Steele L. Paul , Eastham Sebastian D.
Published: October 2016

The distribution of isotopes within O2 molecules can be rapidly altered when they react with atomic oxygen. This mechanism is globally important: while other contributions to the global budget of O2 impart isotopic signatures, the O(3P) + O2 reaction resets all such signatures in the atmosphere on subdecadal timescales. Consequently, the isotopic distribution within O2 is determined by O3 photochemistry and the circulation patterns that control where that photochemistry occurs. The variability of isotopic ordering in O2 has not been established, however. We present new measurements of 18O18O in air (reported as Δ36 values) from the surface to 33 km altitude. They confirm the basic features of the clumped‐isotope budget of O2: Stratospheric air has higher Δ36 values than tropospheric air (i.e., more 18O18O), reflecting colder temperatures and fast photochemical cycling of O3. Lower Δ36 values in the troposphere arise from photochemistry at warmer temperatures balanced by the influx of high‐Δ36 air from the stratosphere. These observations agree with predictions derived from the GEOS‐Chem chemical transport model, which provides additional insight. We find a link between tropical circulation patterns and regions where Δ36 values are reset in the troposphere. The dynamics of these regions influences lapse rates, vertical and horizontal patterns of O2 reordering, and thus the isotopic distribution toward which O2 is driven in the troposphere. Temporal variations in Δ36 values at the surface should therefore reflect changes in tropospheric temperatures, photochemistry, and circulation. Our results suggest that the tropospheric O3 burden has remained within a ±10% range since 1978.
Contribution of soil moisture variability to summer precipitation in the Northern Hemisphere
Authors: Yang Kai , Wang Chenghai , Bao Hongyan
Published: October 2016

The variability and impacts of spring soil moisture (SSM) over the Northern Hemisphere (NH) in the recent 30 years are investigated. The results show that there are two maximum regions of interannual variability of SSM, which are located in the central region of North America (Region 1), and Europe and West Asia (Region 2). These two regions are crucial areas of land‐atmosphere interaction; SSM in these two regions is closely connected with subsequent summer precipitation in NH. Four simulation experiments show that compared to the oceanic effect, the SSM has a positive contribution to summer precipitation over northern Europe, central Asia, and the southern region of North America but a negative contribution to the central region of North America, Arabia, and India, which accounts for 5%–10% of the summer precipitation based on the regional average. The SSM has significant impacts on subsequent summer precipitation in the midlatitudes, while the oceanic impact is dominant over tropical continents. The regions with remarkable variability of SSM are the areas where the coupling between SSM and summer precipitation is relatively strong. The anomalous SSM over NH primarily influences the general circulation through diabatic heating anomalies and changes the low‐level moisture condition, leading to the anomalies of summer precipitation.
A decision tree algorithm for investigation of model biases related to dynamical cores and physical parameterizations
Authors: Soner Yorgun M. , Rood Richard B.
Published: October 2016

An object‐based evaluation method using a pattern recognition algorithm (i.e., classification trees) is applied to the simulated orographic precipitation for idealized experimental setups using the National Center of Atmospheric Research (NCAR) Community Atmosphere Model (CAM) with the finite volume (FV) and the Eulerian spectral transform dynamical cores with varying resolutions. Daily simulations were analyzed and three different types of precipitation features were identified by the classification tree algorithm. The statistical characteristics of these features (i.e., maximum value, mean value, and variance) were calculated to quantify the difference between the dynamical cores and changing resolutions. Even with the simple and smooth topography in the idealized setups, complexity in the precipitation fields simulated by the models develops quickly. The classification tree algorithm using objective thresholding successfully detected different types of precipitation features even as the complexity of the precipitation field increased. The results show that the complexity and the bias introduced in small‐scale phenomena due to the spectral transform method of CAM Eulerian spectral dynamical core is prominent, and is an important reason for its dissimilarity from the FV dynamical core. The resolvable scales, both in horizontal and vertical dimensions, have significant effect on the simulation of precipitation. The results of this study also suggest that an efficient and informative study about the biases produced by GCMs should involve daily (or even hourly) output (rather than monthly mean) analysis over local scales.
Optimizing Bulk Metallic Glasses for Robust, Highly Wear‐Resistant Gears
Authors: Hofmann Douglas C. , Andersen Laura M. , Kolodziejska Joanna , Roberts Scott N. , Borgonia John‐Paul , Johnson William L. , Vecchio Kenneth S. , Kennett Andrew
Published: October 2016

Despite their promising mechanical properties and ability to be manufactured like plastics, bulk metallic glasses (BMGs) are slow to emerge as a structural engineering material. Because BMGs properties are highly correlated with processing, it is necessary to test them in a relevant engineering application. In the current work, CuZr‐based BMGs are developed with excellent wear performance when used as gears. It is shown that in order to optimize the wear performance of these gears, toughness should be maximized. This contrasts the conventional design strategy, where wear performance increases with increasing hardness. Finally, a new low‐cost manufacturing method for casting net‐shaped macroscale gears is developed.
Facile Fabrication of High‐Density Sub‐1‐nm Gaps from Au Nanoparticle Monolayers as Reproducible SERS Substrates
Authors: Si Shaorong , Liang Wenkai , Sun Yinghui , Huang Jing , Ma Weiliang , Liang Zhiqiang , Bao Qiaoliang , Jiang Lin
Published: October 2016

The fabrication of ultrasmall nanogaps (sub‐1 nm) with high density is of significant interest and importance in physics, chemistry, life science, materials science, surface science, nanotechnology, and environmental engineering. However, it remains a challenge to generate uncovered and clean sub‐1‐nm gaps with high density and uniform reproducibility. Here, a facile and low‐cost approach is demonstrated for the fabrication of high‐density sub‐1‐nm gaps from Au nanoparticle monolayers as reproducible surface‐enhanced Raman scattering (SERS) substrates. Au nanoparticles with larger diameters possess lower surface charge, thus the obtained large‐area nanoparticle monolayer generates a high‐density of sub‐1‐nm gaps. In addition, a remarkable SERS performance with a 1011 magnitude for the Raman enhancement is achieved for 120 nm Au nanoparticle monolayers due to the dramatic increase in the electromagnetic field enhancement when the obtained gap is smaller than 0.5 nm. The Au nanoparticle monolayer is also transferred onto a stretchable PDMS substrate and the structural stability and reproducibility of the high‐density sub‐1‐nm gaps in Au monolayer films are illustrated. The resultant Au nanoparticle monolayer substrates with an increasing particle diameter exhibit tunable plasmonic properties, which control the plasmon‐enhanced photocatalytic efficiency for the dimerization of p‐aminothiophenol. The findings reported here offer a new opportunity for expanding the SERS application.
Near‐Infrared Photoresponse of One‐Sided Abrupt MAPbI3/TiO2 Heterojunction through a Tunneling Process
Authors: Yan Keyou , Wei Zhanhua , Zhang Tiankai , Zheng Xiaoli , Long Mingzhu , Chen Zefeng , Xie Weiguang , Zhang Teng , Zhao Yuda , Xu Jianbin , Chai Yang , Yang Shihe
Published: October 2016

Trap states in semiconductors usually degrade charge separation and collection in photovoltaics due to trap‐mediated nonradiative recombination. Here, it is found that perovskite can be heavily doped in low concentration with non‐ignorable broadband infrared absorption in thick films and their trap states accumulate electrons through infrared excitation and hot carrier cooling. A hybrid one‐sided abrupt perovskite/TiO2 p‐N heterojunction is demonstrated that enables partial collection of these trap‐filled charges through a tunneling process instead of detrimental recombination. The tunneling is from broadband trap states in the wide depleted p‐type perovskite, across the barrier of the narrow depleted TiO2 region (<5 nm), to the N‐type TiO2 electrode. The trap states inject carriers into TiO2 through tunneling and produce around‐unity peak external quantum efficiency, giving rise to near‐infrared photovoltaics. The near‐infrared response allows photodetecting devices to work in both diode and conductor modes. This work opens a new avenue to explore the near‐infrared application of hybrid perovskites.
Modulating the Photocatalytic Activity of Graphene Quantum Dots via Atomic Tailoring for Highly Enhanced Photocatalysis under Visible Light
Authors: Jeon Su‐Ji , Kang Tae‐Woog , Ju Jong‐Min , Kim Man‐Jin , Park Jung Hyun , Raza Faizan , Han Juhee , Lee Hye‐Rim , Kim Jong‐Ho
Published: October 2016

Precise control over doping of photocatalysts is required to modulate their photocatalytic activity in visible light‐driven reactions. Here, a single precursor‐employing bottom‐up approach is developed to produce different heteroatom‐doped graphene quantum dots (GQDs) with unique photocatalytic activities. The solvothermal reaction of a norepinephrine precursor with redox active and condensable moieties effectively produces both nitrogen/sulfur codoped GQDs (NS‐GQDs) and nitrogen‐doped GQDs (N‐GQDs) by simply varying solvents (from dimethyl sulfoxide to water) under microwave irradiation. As‐prepared NS‐GQDs and N‐GQDs show similar lateral sizes (3–4 nm) and heights (1–2 nm), but they include different dopant types and doping constitution and content, which lead to changes in photocatalytic activity in aerobic oxidative coupling reactions of various amines. NS‐GQDs exhibit much higher photocatalytic activity in reactions under visible light than N‐GQDs and oxygen‐doped GQDs (O‐GQDs). The mechanism responsible for the outstanding photocatalytic activity of NS‐GQDs in visible light‐driven oxidative coupling reactions of amines is also fully investigated.
Hyaluronic Acid and Its Derivatives in Coating and Delivery Systems: Applications in Tissue Engineering, Regenerative Medicine and Immunomodulation
Authors: Knopf‐Marques Helena , Pravda Martin , Wolfova Lucie , Velebny Vladimir , Schaaf Pierre , Vrana Nihal Engin , Lavalle Philippe
Published: October 2016

As an Extracellular Matrix (ECM) component, Hyaluronic acid (HA) plays a multi‐faceted role in cell migration, proliferation and differentiation at micro level and system level events such as tissue water homeostasis. Among its biological functions, it is known to interact with cytokines and contribute to their retention in ECM microenvironment. In addition to its biological functions, it has advantageous physical properties which result in the industrial endeavors in the synthesis and extraction of HA for variety of applications ranging from medical to cosmetic. Recently, HA and its derivatives have been the focus of active research for applications in biomedical device coatings, drug delivery systems and in the form of scaffolds or cell‐laden hydrogels for tissue engineering. A specific reason for the increase in use of HA based structures is their immunomodulatory and regeneration inducing capacities. In this context, this article reviews recent literature on modulation of the implantable biomaterial microenvironment by systems based on HA and its derivatives, particularly hydrogels and microscale coatings that are able to deliver cytokines in order to reduce the adverse immune reactions and promote tissue healing.
Expanded 3D Nanofiber Scaffolds: Cell Penetration, Neovascularization, and Host Response
Authors: Jiang Jiang , Li Zhuoran , Wang Hongjun , Wang Yue , Carlson Mark A. , Teusink Matthew J. , MacEwan Matthew R. , Gu Linxia , Xie Jingwei
Published: October 2016

Herein, a robust method to fabricate expanded nanofiber scaffolds with controlled size and thickness using a customized mold during the modified gas‐foaming process is reported. The expansion of nanofiber membranes is also simulated using a computational fluid model. Expanded nanofiber scaffolds implanted subcutaneously in rats show cellular infiltration, whereas non‐expanded scaffolds only have surface cellular attachment. Compared to unexpanded nanofiber scaffolds, more CD68+and CD163+cells are observed within expanded scaffolds at all tested time points post‐implantation. More CCR7+cells appear within expanded scaffolds at week 8 post‐implantation. In addition, new blood vessels are present within the expanded scaffolds at week 2. The formed multinucleated giant cells within expanded scaffolds are heterogeneous expressing CD68, CCR7, or CD163 markers. Together, the present study demonstrates that the expanded nanofiber scaffolds promote cellular infiltration/tissue integration, a regenerative response, and neovascularization after subcutaneous implantation in rats. The use of expanded electrospun nanofiber scaffolds offers a promising method for in situ tissue repair/regeneration and generation of 3D tissue models/constructs.