bluuebunny/crossref_metadata_2025 huggingface dataset:
Glass Structures and Linea/Nonlinear Optical Properties of Ag2O-Doped TeO2 Glasses
Authors: Kasuya Yusuke , Suhara Toshiki , Hayakawa Tomokatsu , Thomas Philippe , Nogami Masayuki
Published: June 2014

A family of TeO2-based glasses is known to have high third-order nonlinear properties and expected as nonlinear optical devices. In the present study, we fabricated Ag2O-TeO2 and Ag2O-Nb2O5-TeO2 glasses, and estimated their structures and linear/nonlinear optical properties. The main results showed that the absorption-edge of the glasses was shifted to longer wavelength side with increasing Ag2O content. By Raman spectroscopy, it was found that an increase in Ag2O content promoted to change TeO4 to TeO3/TeO3+1 units. X-ray photoelectron spectroscopy (XPS) revealed the presence of an electronic state of Ag2+ ions, which was supposed to have a large influence on the absorption-edge wavelength. In Ag2O-Nb2O5-TeO2 glass system, the third-order nonlinear susceptibility χ(3) increased with increasing Ag2O content at the expense of Nb2O5 content.
Fabrication of Hollow Silica-Alumina Composite Spheres Using L(+)-Arginine and their Catalytic Performance for Hydrolytic Dehydrogenation of Ammonia Borane
Authors: Umegaki Tetsuo , Imamura Shunsuke , Toyama Naoki , Xu Qiang , Kojima Yoshiyuki
Published: June 2014

The present study reports a facile and effective approach for fabrication of hollow silica-alumina composite spheres. In this approach, silica-alumina composite walls were coated on polystyrene template by the sol-gel method using L(+)-arginine as a promoter for the reaction followed by calcination procedure. Using L(+)-arginine as a promoter of coating process, homogeneous hollow silica-alumina composite spheres are obtained and the wall thickness is larger than that of the hollow spheres prepared with ammonia. The hollow spheres shows high activity for hydrolytic dehydrogenation of ammonia borane compared with spherical silica-alumina composite particles without hollow structure, the hollow spheres prepared with ammonia, and conventional H-BEA zeolite. The results indicate that hollow structure plays important role to show high activity.
Synthesis and Growth Mechanism of SiC/SiO2 Core-Shell Nanowires by Thermal Evaporation Method
Authors: Jiraborvornpongsa Noppasint , Imai Masamitsu , Yoshida Katsumi , Yano Toyohiko
Published: June 2014

In this study, SiC/SiO2 core-shell nanowires (SiCNWs) were fabricated by thermal evaporation method without any catalyst, using pre-oxidized silicon powder and methane (CH4) gas as precursors. The reaction temperature was 1340°C in an inert atmosphere. The SiCNWs produced by this process had a single crystal β-SiC core ranging from 20 to 80 nm in diameter and low-crystalline SiO2 shell about 10-20 nm thick, and up to 1 mm long. The exhaust gas from the production system was analyzed by gas chromatography and the growth activity of SiCNWs was captured by digital camera during a soaking period. From the results, CO gas was detected only when SiCNWs were growing and was not found when methane gas was stopped. It was clarified that CO gas was produced as a by-product during the formation of SiCNWs. The formation mechanism of SiCNWs synthesized by thermal evaporation method was suggested to be oxide-assisted growth mechanism.
Fabrication and Fracture Toughness of CNTs/Alumina Composites with Fine Microstructures
Authors: Ueda Naoki , Yamakami Tomohiko , Yamaguchi Tomohiro , Endo Morinobu , Saito Naoto , Taruta Seiichi
Published: June 2014

Thin carbon nanotubes (CNTs) were heated at 2800°C to heighten the crystallinity of the CNTs. The microstructures and fracture toughness of the thin CNTs and the heat-treated thin CNTs/alumina composites were investigated. Using such thin CNTs was effective for obtaining finer microstructures of the composites but the heat-treatment made the uniform dispersion of the CNTs difficult. The composites containing the heat-treated thin CNTs showed higher fracture toughness than those containing the thin CNTs and the thick CNTs used in previous study when their content was the same.
Interface Formation of Unidirectional SiCf/SiC Composites by Electrophoretic Deposition Method
Authors: Yoshida Katsumi , Akimoto Hiroyuki , Yamauchi Akihiro , Yano Toyohiko , Kotani Masaki , Ogasawara Toshio
Published: June 2014

C-and BN-interphases on SiC fibers for unidirectional SiCf/SiC composites were formed by EPD process, and their microstructure and mechanical properties were investigated. Whereas the C-SiCf/SiC composites showed a pseudo-ductile fracture behavior with large amount of fiber pullout, the BN-SiCf/SiC composites fractured in a brittle manner without fiber pullout in spite of sufficient thickness of BN interphase. It is inferred from the results of EDS that sintering additives would react with h-BN-interphase, and the interphase did not act effectively for toughening the SiCf/SiC composites.
Low-Temperature Synthesis of MgAl2O4 by Capsule HIP Using Hydroxides as Starting Materials
Authors: Yanagida Kensuke , Yamaguchi Yuki , Fujimoto Kenjiro , Ito Shigeru
Published: June 2014

Low-temperature synthesis of spinel (MgAl2O4) was investigated by capsule hot isostatic press (HIP) using hydroxides as starting materials; Mg(OH)2, MgO, Al(OH)3, g-AlOOH, g-Al2O3. MgAl2O4 has been conventionally prepared above 1400 °C, whereas the mixtures containing the hydroxides reacted at 400-500 °C for 1 h under 200 MPa of isostatic pressure to form MgAl2O4. The hydroxides showed high reactivity to form MgAl2O4 with high crystallinity. However, the products more or less contained Mg(OH)2. The single phase of MgAl2O4 was obtained by adding 20 mass% of water to the starting mixtures of Mg(OH)2 - Al(OH)3, Mg(OH)2 - g-Al2O3 and MgO - Al(OH)3. The average grain size of the MgAl2O4 was 70 – 100 nm. It was concluded that the transformation of AlOOH or g-Al2O3 was promoted by a small amount of water and that Mg(OH)2 rapidly reacted with the active intermediate compound between AlOOH or g-Al2O3 and a-Al2O3.
Synthesis of Bio-Cation-Substituted Ca-Apatites by Precipitation
Authors: Bogdanoviciene Irma , Tõnsuaadu Kaia , Traksmaa Rainer , Kareiva Aivaras
Published: June 2014

Nanosize Mg2+, Zn2+, Sr2+, and Na+ mono- and di-substituted calcium hydroxyapatites were synthesized using an aqueous precipitation route under controlled conditions. The chemical composition and the micro-structural features of the polycrystalline samples were characterized by chemical analysis, thermal analysis (TG/DTA) combined with MS for evolved gas analysis, FTIR and XRD spectroscopy as well as SEM. The correlations between chemical composition and the crystal morphology were elucidated.
Immobilization Reaction of Chromate Ion Using Ca4Al2(OH)12·Cl2·4H2O
Authors: Ohya Junichi , Sango Hiroyuki , Sakai Etsuo
Published: June 2014

Hydrocalmite-like hydrate is one of calcium aluminate hydrated products. This hydrate has a layer structure and the principal layer, which is similar to calcium hydroxide define alternate with interlayer including divalent anions and water molecules. Their anions are able to react with outer anions by anion-exchange reaction. In this study, anion-exchange reaction between hydrocalmite-like hydrate including chloride anion (Ca4Al2(OH)12·Cl2·4H2O, Cl-HC) and chromate anion (CrO42-) is examined. CrO42- is immobilized in various hydrated forms, which are varied with an increasing in the additive ratio of CaCrO4 to Cl-HC. As the additive ratio of CaCrO4 to Cl-HC is below 1.0 in molar, Ca4Al2(OH)12·CrO4·nH2O (n=6 or 8, CrO4-HC) is formed. In this case, the concentration of chromate ion in solution is less than 1.0 ×10-3 mol·dm-3 and over 99% of chromium immobilize in solid phase. However, when the additive ratio of CaCrO4 is over 1.0, ettringite type hydrate including CrO42- (Ca6Al2(OH)12·3CrO4 ·26H2O) is generated and over 10 % of chromium is eluted from the solid phase.
Optimization of Module Shape in Thermoelectric Power Generation
Authors: Suzuki Ryosuke O. , Fujisaka Takeyuki
Published: June 2014

Heat and electric charge transfer through the thermoelectric (TE) module were analyzed numerically. The thermal heat can expand or shrink in the trapezoid shape in comparison with the conventional Π type module, and the output and efficiency from the module with trapezoid TE elements was examined from the view of shape optimization. The temperature profile and some thermoelectric properties were calculated using the infinite volume method and the original code. The temperature profile in the module showed a complex distribution in the TE elements, however, the efficiency in power generation did not change from that of the rectangular TE module.
Mechanical Performances of Super Sulfated Cements
Authors: Baux Christophe , Phelipot-Mardelé Annabelle , Lanos Christophe , Pierre Alexandre
Published: June 2014

Tested super sulfated cements (SSC) are composed with various amounts of ground granulated blast furnace slag, gypsum or activated gypsum and Portland cement. Our initial results on the optimization of the composition and of the curing conditions of such cements are presented herein. Tests are conducted on the basis of standard mortar with two different gauging ratios according to old and new standards for SSC. Four types of curing are used. Mechanical performances are assessed at 2, 7, 28, 60 and 90 days on standard mortar samples (binder/sand mass ratio = 1/3). This study shows that, thanks to an optimization of the Portland cement content, it is completely possible to obtain super sulfated cement with a strength class 32.5N, and always in conformity with the new European standard. For a given SSC formulation, it is clearly demonstrated that the origin of the calcium sulfate addition that affects the development of sulfo-aluminous compounds in these mixtures constitutes a key point in the phenomena of setting and hardening. The use of heat-activated gypsum as a sulfate activator appears preferable.
Role of Siliceous Species in Geopolymer Reactant Mixture: Interaction with (NH4)2Mo2O7
Authors: Vidal Laëticia , Autef Alexandre , Selmani Samira , Joussein Emmanuel , Rossignol Sylvie
Published: June 2014

Geopolymers are inorganic materials having interesting properties for many using areas. It is well known that geopolymers present various properties depending on the aluminosilicate sources used but lack of understanding are effective. This study consists on the comprehension of the formation of different networks in geopolymers by modify the reactivity of siliceous species in the reactive mixture with ammonium molybdate. These experiments evidenced the existence of various polycondensation reactions between materials leading to the formation of different networks. Moreover the use of ammonium molybdate addition in the mixture induces a slowdown of the reaction.
Co80Ni20 Nanowires-Based Tunable Sintered Materials
Authors: Ouar Nassima , Schoenstein Frédéric , Mercone Silvana , Villeroy Benjamin , Leridon Brigitte , Farhat Samir , Jouini Noureddine
Published: June 2014

This work focuses on the development and study of nanostructured magnetic materials by a " bottom-up " strategy allowing the modulation of their magnetic behavior (soft to - hard). The main goal of this work is to tune the magnetic bulk coercivity properties of new nanostructured bulk materials based on magnetic nanowires assembly. Spark-Plasma-Sintering (SPS) process allows an organization of magnetic nanowires inside the sintered material and preserving at the same time the nanoscale character of the nanowires in order to take advantage of the confinement peculiar magnetic properties. We show here that changing the temperature and magnetic field parameters during this new sintering process is at the origin of a controlled anisotropy and coercitivity in the as-obtained bulk systems.
Mechanochemical/Solvothermal Synthesis of LiMn2O4 as a Cathode Material for Rechargeable Batteries
Authors: Abe Osami , Sato S. , Mitachi S. , Yamada T.
Published: June 2014

Highly-crystallized fine LiMn2O4 powders have been synthesized by a combination of the mechanochemical (MC) and solvothermal (ST) treatments of LiOH and MnO2 in Acetone. The MC product is amorphous, but, shows the formation of Mn-O-Li bond. The ST post treatment promotes the nucleation of LiMn2O4 by the chemical reduction of Mn4+ to Mn3+. The estimated chemical compositions are LiMn (III)0.11Mn (IV)1.89O4.45 (MC) and LiMn (III)0.76Mn (IV)1.12O3.88 (MC/ST). The MC/ST powder crystallized at 800°C indicates the cell capacity of 119mA.h.g-1. The dilution of Acetone with Tetrahydrofuran is effective to reduce the particle size. The MC/ST product using the diluent shows the fine particle size of 150nm and the excellent cell capacity of 134mA.h.g-1.
Process Study of Nanosized Powder Dispersion for DEFC
Authors: Niwa Koichi , Tanaka Toshiaki , Ikuma Yasuro
Published: June 2014

The process of obtaining a uniform dispersion of nanosized powders by applying two step process of mixing and adjusting viscosity was studied. The mixed paste was used as the electrode of direct ethanol fuel cells (DEFC). And power density of the fuel cells was measured. A high power density was realized by addition of acetone and propanol solvents to nanosized silica powder. However acetaldehyde concentration during the operation of these fuel cells did not decrease. An excess methanol was added to membrane electrode assembly composition of DEFC. The power density and current of DEFC were improved by adding methanol solvent. However, methanol addition over 55 % did not improve dispersion of nanosized powders. Transmission electron microscopy observation suggests that over 55% of methanol addition does not give good dispersion of nanosized powders.
Structure and Reactivity of the La2-xSrXMnO4±δ (0.7≤ X ≤1.0) Solid Solutions in Oxidizing Condition
Authors: Broux Thibault , Briand M. , Prestipino C. , Hernandez Olivier , Bahout Mona
Published: June 2014

Single phase La2xSrxMnO4±δ (0.7 x 1.0) solid solutions were prepared via sol-gel synthesis. For all the compositions the structure turns out to be tetragonal I4/mmm. Samples were then heated for 12 h at different temperatures in O2 to investigate the structural response to oxygen uptake. On increasing the La/Sr ratio the maximum amount of oxygen inserted (δ) reaches for x = 0.7 an unprecedented value of δ ~ 0.47 in K2NiF4-structure type oxides, as evidenced from iodometric titration and thermogravimetric analysis. For the x 0.8 compositions the oxidation resulted in an intermediate orthorhombic phase.
Context-specific enhanced invasiveness ofRaphanuscrop–wild hybrids: A test for associations between greater fecundity and population growth
Authors: Campbell Lesley G. , Teitel Zachary , Miriti Maria N. , Snow Allison A.
Published: June 2014

Campbell, L. G., Teitel, Z., Miriti, M. N. and Snow, A. A. 2014. Context-specific enhanced invasiveness of Raphanus crop–wild hybrids: A test for associations between greater fecundity and population growth. Can. J. Plant Sci. 94: 1315–1324. Evolution by crop–wild hybridization may create plant lineages with greater population growth rates, dispersal, and persistence than weedy progenitors, depending upon plant density. We asked: (1) how does hybridization affect demography and population growth rate (lambda, λ) and (2) how does density affect demography and λ? Over 1 yr, we followed wild radish, Raphanus raphanistrum and crop-wild hybrid, Raphanus sativus×R. raphanistrum, plants grown in 18 experimental sub-populations (originally derived from three wild and three hybrid populations) to assess contributions of germination, survival, and seed production to λ. We explored genotypic differences in demographic characteristics of low- and high-density populations (from populations grown at unmanipulated densities for three generations), using a LTRE. Hybrid populations had greater λs than weedy progenitors when grown in low (but not high) densities. Seed production was more influential on λ than germination or survival, and seed mortality was least influential. Our results indicate weedy Raphanus populations may be best controlled by limiting seed production, rather than killing plants outright or preventing seeds from germinating. Furthermore, relative invasiveness of genotypes is density-dependent, low-density conditions improving potential invasiveness of hybrid populations. We emphasize that assessing invasive potential of a plant will be more successful if one uses a comprehensive demographic approach accounting for a weed's entire life history.
Impact of the Affordable Care Act on Grant-Supported Primary Care Faculty Development
Authors: Klink Kathleen A. , Joice Sylvia E. , McDevitt Shannon K.
Published: June 2014

Health reform requires well-trained primary care physicians with new skills. Teaching faculty need to develop proficiency to deliver care in new models and systems, to lead change, and to teach these skills to the next generation of clinicians. Title VII Section 747 of the Public Health Service Act, modified and reauthorized under the Patient Protection and Affordable Care Act (ACA), is the only federal program that specifically supports the professional development of primary care faculty. We analyzed the effect of the modifications under the ACA on a funding opportunity announcement addressing faculty development needs and attributes of funded applications, including geographic regions. The data offer useful insights to programs interested in tapping sources of support for primary care faculty development. The data also show that targeted federal funding can bring about changes that contribute to an up-to-date, responsive primary care workforce. Title VII programs, as amended by the ACA, focus on curriculum development, teaching in community-based settings, and integrating patient-centered medical home concepts and interprofessional education and practice into the training of the next generation of physicians. These strategies drive change and improve the quality of care and patient outcomes.
Sensitivity analysis of an updated bidirectional air–surface exchange model for elemental mercury vapor
Authors: Wang X. , Lin C.-J. , Feng X.
Published: June 2014

Abstract. A box model for estimating bidirectional air–surface exchange of gaseous elemental mercury (Hg0) has been updated based on the latest understanding of the resistance scheme of atmosphere–biosphere interface transfer. Simulations were performed for two seasonal months to evaluate diurnal and seasonal variation. The base-case results show that water and soil surfaces are net sources, while vegetation is a net sink of Hg0. The estimated net exchange in a domain covering the contiguous US and part of Canada and Mexico is 38.4 and 56.0 Mg as evasion in the summer and winter month, respectively. The smaller evasion in summer is due to the stronger Hg0 uptake by vegetation. Modeling experiments using a two-level factorial design were conducted to examine the sensitivity of flux response to the changes in physical and environmental parameters in the model. It is shown that atmospheric shear flows (surface wind over water and friction velocity over terrestrial surfaces), dissolved gaseous mercury (DGM) concentration, soil organic and Hg content, and air temperature are the most influential factors. The positive effect of friction velocity and soil Hg content on the evasion flux from soil and canopy can be effectively offset by the negative effect of soil organic content. Significant synergistic effects are identified between surface wind and DGM level for water surface, and between soil Hg content and friction velocity for soil surface, leading to ~50% enhanced flux compared to the sum of their individual effects. The air–foliage exchange is mainly controlled by surface resistance terms influenced by solar irradiation and air temperature. Research in providing geospatial distribution of Hg in water and soil will greatly improve the flux estimate. Elucidation on the kinetics and mechanism of Hg(II) reduction in soil/water and quantification of the surface resistances specific to Hg species will also help reduce the model uncertainty.
High resolution observations of the near-surface wind field over an isolated mountain and in a steep river canyon
Authors: Butler B. W. , Wagenbrenner N. S. , Forthofer J. M. , Lamb B. K. , Shannon K. S. , Finn D. , Eckman R. M. , Clawson K. , Bradshaw L. , Sopko P. , Beard S. , Jimenez D. , Wold C. , Vosburgh M.
Published: June 2014

Abstract. A number of numerical wind flow models have been developed for simulating wind flow at relatively fine spatial resolutions (e.g., ∼100 m); however, there are very limited observational data available for evaluating these high resolution models. This study presents high-resolution surface wind datasets collected from an isolated mountain and a steep river canyon. The wind data are presented in terms of four flow regimes: upslope, afternoon, downslope, and a synoptically-driven regime. There were notable differences in the data collected from the two terrain types. For example, wind speeds collected on the isolated mountain increased with distance upslope during upslope flow, but generally decreased with distance upslope at the river canyon site during upslope flow. Wind speed did not have a simple, consistent trend with position on the slope during the downslope regime on the isolated mountain, but generally increased with distance upslope at the river canyon site. The highest measured speeds occurred during the passage of frontal systems on the isolated mountain. Mountaintop winds were often twice as high as wind speeds measured on the surrounding plain. The highest speeds measured in the river canyon occurred during late morning hours and were from easterly downcanyon flows, presumably associated with surface pressure gradients induced by formation of a regional thermal trough to the west and high pressure to the east. Under periods of weak synoptic forcing, surface winds tended to be decoupled from large-scale flows, and under periods of strong synoptic forcing, variability in surface winds was sufficiently large due to terrain-induced mechanical effects (speed-up over ridges and decreased speeds on leeward sides of terrain obstacles) that a large-scale mean flow would not be representative of surface winds at most locations on or within the terrain feature. These findings suggest that traditional operational weather model (i.e., with numerical grid resolutions of around 4 km or larger) wind predictions are not likely to be good predictors of local near-surface winds at sub-grid scales in complex terrain. The data from this effort are archived and available at: http://www.firemodels.org/index.php/windninja-introduction/windninja-publications.
Radiation in the neighbourhood of a double layer
Authors: Pottelette R. , Berthomier M. , Pickett J.
Published: June 2014

Abstract. In the auroral kilometric radiation (AKR) source region, acceleration layers narrow in altitude and associated with parallel field-aligned potential drops of several kV can be identified by using both particles and wave-field high time-resolution measurements from the Fast Auroral SnapshoT explorer spacecraft (FAST). These so-called double layers (DLs) are recorded around density enhancements in the auroral cavity, where the enhancement can be at the edge of the cavity or even within the cavity at a small scale. Once immersed in the plasma, DLs necessarily accelerate particles along the magnetic field lines, thereby generating locally strong turbulent processes leading to the formation of nonlinear phase space holes. The FAST data reveal the asymmetric character of the turbulence: the regions located on the high-potential side of the DLs are characterized by the presence of electron holes, while on the low-potential side, ion holes are recorded. The existence of these nonlinear phase space holes may affect the AKR radiation pattern in the neighbourhood of a DL where the electron distribution function is drastically different from a horseshoe shape. We present some observations which illustrate the systematic generation of elementary radiation events occurring significantly above the local electron gyrofrequency in the presence of electron holes. These fine-scale AKR radiators are associated with a local electron distribution which presents a pronounced beam-like shape.
Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)
Authors: Berndmeyer C. , Thiel V. , Schmale O. , Wasmund N. , Blumenberg M.
Published: June 2014

Abstract. The water column of the Landsort Deep, central Baltic Sea, is stratified into an oxic, suboxic and anoxic zone. This stratification controls the distributions of individual microbial communities and biogeochemical processes. In summer 2011, particulate organic matter was filtered from these zones using an in~situ pump. Lipid biomarkers were extracted from the filters to establish water column profiles of individual hydrocarbons, alcohols, phospholipid fatty acids, and bacteriohopanepolyols (BHPs). As a reference, a cyanobacterial bloom sampled in summer 2012 in the central Baltic Sea Gotland Deep was analyzed for BHPs. The biomarker data from the surface layer of the oxic zone showed major inputs from different cyanobacteria and eukaryotes such as dinoflagellates and ciliates, while the underlying cold winter water layer was characterized by a low diversity and abundance of organisms, with copepods as a major group. The suboxic zone supported bacterivorous ciliates, type I aerobic methanotrophic bacteria, sulfate reducing bacteria, and, most likely, methanogenic archaea. In the anoxic zone, sulfate reducers and archaea were the dominating microorganisms as indicated by the presence of distinctive branched fatty acids, archaeol and PMI derivatives, respectively. Our study of in situ biomarkers in the Landsort Deep thus provided an integrated insight into the distribution of relevant players and the related biogeochemical processes in stratified water columns of marginal seas.
Are recent changes in sediment manganese sequestration in the euxinic basins of the Baltic Sea linked to the expansion of hypoxia?
Authors: Lenz C. , Jilbert T. , Conley D. J. , Wolthers M. , Slomp C. P.
Published: June 2014

Abstract. Expanding hypoxia in the Baltic Sea over the past century has led to anoxic and sulfidic (euxinic) deep basins that are only periodically ventilated by inflows of oxygenated waters from the North Sea. In this study, we investigate the consequences of the expanding hypoxia for manganese (Mn) burial in the Baltic Sea using a combination of pore water and sediment analyses of well-dated sediment cores from 8 locations. Diffusive fluxes of dissolved Mn from sediments to overlying waters at oxic and hypoxic sites are in line with an active release of Mn from these areas. However, this flux of Mn is only small when compared to the large pool of Mn already present in the hypoxic and anoxic water column. Our results highlight two modes of Mn carbonate formation in sediments of the deep basins. In the Gotland Deep area, Mn carbonates likely form from Mn oxides that are precipitated from the water column directly following North Sea inflows. In the Landsort Deep, in contrast, Mn carbonate and Mn sulfide layers form independent of inflow events, with pore water Mn produced in deeper layers of the sediment acting as a key Mn source. While formation of Mn enrichments in the Landsort Deep continues to the present, this does not hold for the Gotland Deep area. Here, increased euxinia, as evident from measured bottom water sulfide concentrations and elevated sediment molybdenum (Mo), goes hand in hand with a decline in sediment Mn and recent inflows of oxygenated water (since ca. 1995) are no longer consistently recorded as Mn carbonate layers. We postulate that the reduction of Mn oxides by hydrogen sulfide following inflows has become so rapid that Mn2+ is released to the water column before Mn carbonates can form. Our results have important implications for the use of Mn carbonate enrichments as a redox proxy in marine systems.
The spectral element method on variable resolution grids: evaluating grid sensitivity and resolution-aware numerical viscosity
Authors: Guba O. , Taylor M. A. , Ullrich P. A. , Overfelt J. R. , Levy M. N.
Published: June 2014

Abstract. We evaluate the performance of the Community Atmosphere Model's (CAM) spectral element method on variable resolution grids using the shallow water equations in spherical geometry. We configure the method as it is used in CAM, with dissipation of grid scale variance implemented using hyperviscosity. Hyperviscosity is highly scale selective and grid independent, but does require a resolution dependent coefficient. For the spectral element method with variable resolution grids and highly distorted elements, we obtain the best results if we introduce a tensor-based hyperviscosity with tensor coefficients tied to the eigenvalues of the local element metric tensor. The tensor hyperviscosity is constructed so that for regions of uniform resolution it matches the traditional constant coefficient hyperviscsosity. With the tensor hyperviscosity the large scale solution is almost completely unaffected by the presence of grid refinement. This later point is important for climate applications where long term climatological averages can be imprinted by stationary inhomogeneities in the truncation error. We also evaluate the robustness of the approach with respect to grid quality by considering unstructured conforming quadrilateral grids generated with a well-known grid-generating toolkit and grids generated by SQuadGen, a new open source alternative which produces lower valence nodes.
Hydrogeology of an alpine rockfall aquifer system and its role in flood attenuation and maintaining baseflow
Authors: Lauber U. , Kotyla P. , Morche D. , Goldscheider N.
Published: June 2014

Abstract. The frequency and intensity of extreme hydrological events in alpine regions is projected to increase with climate change. The goal of this study was to better understand the functioning of aquifers composed of complex alluvial and rockfall deposits in alpine valleys and to quantify the role of these natural storage spaces in flood attenuation and baseflow maintenance. Geomorphological and hydrogeological mapping, tracer tests, and continuous flow measurements were conducted in the Reintal valley (German Alps), where runoff from a karst spring infiltrates into a series of postglacial alluvial/rockfall aquifers. During high-flow conditions, groundwater velocities of 30 m h−1 were determined along 500 m; hydrograph analyses revealed short lag times (5 h) between discharge peaks upstream and downstream from the aquifer series; the maximum discharge ratio downstream (22) and the peak recession coefficient (0.196 d−1) are low compared with other alpine catchments. During low-flow conditions, the underground flow path length increased to 2 km and groundwater velocities decreased to 13 m h−1. Downstream hydrographs revealed a delayed discharge response after 101 h and peaks dampened by a factor of 1.5. These results indicate that alluvial/rockfall aquifers might play an important role in the flow regime and attenuation of floods in alpine regions.
Testing the detectability of spatio–temporal climate transitions from paleoclimate networks with the START model
Authors: Rehfeld K. , Molkenthin N. , Kurths J.
Published: June 2014

Abstract. A critical challenge in paleoclimate data analysis is the fact that the proxy data are heterogeneously distributed in space, which affects statistical methods that rely on spatial embedding of data. In the paleoclimate network approach nodes represent paleoclimate proxy time series, and links in the network are given by statistically significant similarities between them. Their location in space, proxy and archive type is coded in the node attributes. We develop a semi-empirical model for Spatio-Temporally AutocoRrelated Time series, inspired by the interplay of different Asian Summer Monsoon (ASM) systems. We use an ensemble of transition runs of this START model to test whether and how spatio–temporal climate transitions could be detectable from (paleo)climate networks. We sample model time series both on a grid and at locations at which paleoclimate data are available to investigate the effect of the spatially heterogeneous availability of data. Node betweenness centrality, averaged over the transition region, does not respond to the transition displayed by the START model, neither in the grid-based nor in the scattered sampling arrangement. The regionally defined measures of regional node degree and cross link ratio, however, are indicative of the changes in both scenarios, although the magnitude of the changes differs according to the sampling. We find that the START model is particularly suitable for pseudo-proxy experiments to test the technical reconstruction limits of paleoclimate data based on their location, and we conclude that (paleo)climate networks are suitable for investigating spatio–temporal transitions in the dependence structure of underlying climatic fields.
Characterizing the evolution of climate networks
Authors: Tupikina L. , Rehfeld K. , Molkenthin N. , Stolbova V. , Marwan N. , Kurths J.
Published: June 2014

Abstract. Complex network theory has been successfully applied to understand the structural and functional topology of many dynamical systems from nature, society and technology. Many properties of these systems change over time, and, consequently, networks reconstructed from them will, too. However, although static and temporally changing networks have been studied extensively, methods to quantify their robustness as they evolve in time are lacking. In this paper we develop a theory to investigate how networks are changing within time based on the quantitative analysis of dissimilarities in the network structure. Our main result is the common component evolution function (CCEF) which characterizes network development over time. To test our approach we apply it to several model systems, Erdős–Rényi networks, analytically derived flow-based networks, and transient simulations from the START model for which we control the change of single parameters over time. Then we construct annual climate networks from NCEP/NCAR reanalysis data for the Asian monsoon domain for the time period of 1970–2011 CE and use the CCEF to characterize the temporal evolution in this region. While this real-world CCEF displays a high degree of network persistence over large time lags, there are distinct time periods when common links break down. This phasing of these events coincides with years of strong El Niño/Southern Oscillation phenomena, confirming previous studies. The proposed method can be applied for any type of evolving network where the link but not the node set is changing, and may be particularly useful to characterize nonstationary evolving systems using complex networks.
Influence of long-term mineral fertilization on metal contents and properties of soil samples taken from different locations in Hesse, Germany
Authors: Czarnecki S. , Düring R.-A.
Published: June 2014

Abstract. Essential and non-essential metals occur in soils as a result of weathering, industrial processes, fertilization and atmospheric deposition. Badly adapted cultivation of agricultural soils (declining pH-value, application of unsuitable fertilizers) can enhance the mobility of metals and by the way increase their concentrations in agricultural products. The main objective of this study was to test the effects of different mineral fertilizer variations on soil properties (pH, Corg and CEC) and pseudo total and mobile metal contents of soils after 14 years of fertilizer application and to determine residual effects of the fertilization 8 years after cessation of fertilizer treatment. Soil samples were taken from a field experiment which was carried out at four different locations 210, 260, 360, and 620 m a.s.l., in Hesse, Germany. During the study, a significant decrease in soil pH and an evident increase in soil carbon content and cation exchange capacity with fertilization were determined. The CEC of the soils was closely related to their organic C contents. Moreover, pseudo and mobile metal (Cd, Cu, Mn, Pb, Zn) contents in the soils increased due to application of 14 years mineral fertilizer treatments (N, P, NP, and NPK) when compared to control plots. Fertilization is one of the major paths for metal input to agricultural soils, therefore monitoring of the long term impact of fertilization is necessary. 8 years after termination of the fertilization in the soil samples taken from soil profiles of the fertilized plots (NPK) for monitoring the residual effects of the fertilizer application, a decrease of 82.6%, 54.2%, 48.5%, 74.4%, and 56.9%, respectively, in pseudo total Cd, Cu, Mn, Pb, and Zn contents was determined.
Glacier change in the Cariboo Mountains, British Columbia, Canada (1952–2005)
Authors: Beedle M. J. , Menounos B. , Wheate R.
Published: June 2014

Abstract. We calculated dimensional change for 33 glaciers in the Cariboo Mountains of British Columbia for the latter half of the twentieth century. All glaciers receded during the period 1952–2005; area retreat averaged −0.19 ± 0.05% a−1. From 1952 to 1985, nine glaciers advanced. Following 1985, retreat rates accelerated to −0.41 ± 0.12% a−1. Thinning rates likewise accelerated, from −0.14 ± 0.04 m w.e. a−1 (1952–1985) to −0.50 ± 0.07 m w.e. a−1 for the period 1985–2005. Temperatures increased from the earlier to the latter period for the ablation (+0.38 °C) and accumulation (+0.87 °C) seasons, and average precipitation decreased, particularly in the accumulation season (−32 \\unit{mm}, −3.2%). Our comparison of surface area change with glacier morphometry corroborates previous studies that show primary relations between extent change and surface area. We also find, however, that the strength and sign of these relations varied for different epochs.
EPDM RECYCLED RUBBER POWDER CHARACTERIZATION: THERMAL AND THERMOGRAVIMETRIC ANALYSIS
Authors: Liang Huan , Hardy Jean-Michel , Rodrigue Denis , Brisson Josée
Published: June 2014

Investigations on ethylene–propylene–diene rubber (EPDM) with varying cross-link densities and carbon black contents, as well as commercial EPDM waste ground rubber (WGR), have been performed to improve characterization. The aim is to provide additional quality-control methods in the field of rubber recycling, as WGR is transformed and reused in the form of rubber mats mainly for playground, agricultural, sport, and automobile applications. Inductively coupled plasma optical emission spectrometry, atomic absorption spectrometry, and elemental (CHNS) analyses were used to determine the content of various chemical elements. Thermogravimetric analysis (TGA) was used to determine the amount of carbon black and inorganic material in the sample. Mass loss at 400 °C was related to cross-link density. TGA coupled with mass spectrometry showed that this mass loss corresponds to the loss of SO2 as cross-links are destroyed during heating. Melt point and glass transition temperatures determined by differential scanning calorimetry are mainly proportional to the ethylene/propylene weight ratio.
Return Intentions of Malaysia’s Diaspora: The Push and Pull Factors
Authors: Hoo Quah Chun , Zainal Siti Rohaida M. , Chai Guok Eng
Published: June 2014

Despite the huge allocation on funds and attention channeled towards solving the brain drain issue by the Malaysian government, this issue is still far from being resolved. Agencies such as Ministry of Science, Technology and Innovation (MOSTI), Malaysian Development Corporation (MDC) and others have been established to try to lure back our top talents from abroad. MOSTI launched its first brain gain programme in 1995 till 2000, which successfully attracted 94 scientists, of whom only one remains in Malaysia. The second brain gain scheme which was implemented from 2001 to 2004 was intended to attract 5000 talents a year. Unfortunately, only 200 took advantage of the offer. Then, to better coordinate the plan, Talent Corporation Malaysia Berhad was established under the Prime Minister’s Department with the objective of wooing foreign talent and overcoming the barriers for them to settle down in Malaysia, among others (Starbizweek, 2011b). Unfortunately, the reception to these initiatives is far from encouraging. Even though the study on brain drain is not new among researchers; in Malaysia, empirical studies on this issue is still limited. Drawing on the push and pull factors identified by previous researchers, this paper attempts to conceptualize which of these factors have the greatest potential of influencing the return intentions of Malaysia’s top talents working abroad. Proposing two propositions, these conceptual papers then analyzes related articles on the facts about brain drain. The implications of this paper are discussed from two perspectives namely are from the company as well as from the country perspectives. In conclusion, this paper manages to highlight the push and the pull factors influencing brain drain phenomenon in Malaysia.
Atypical Sino-Orbital Inflammatory Myofibroblastic Tumor with Bone and Cerebral Invasion Extending to the Orbit
Authors: Lauwers Noémie , De Groot Veva , Kenis Christoph , Ní Dhubhghaill Sorcha , Claes Jos , De Keizer Robert J.W.
Published: June 2014

Purpose

To report the case of an atypical sino-orbital inflammatory myofibroblastic tumor.

Methods

Case report.

Results

A 71-year-old man presented slowly progressive painless diplopia followed by unilateral proptosis of the left eye with slight edema of the upper eyelid. Visual acuity was 0.4 with a relative afferent pupillary defect (RAPD). Abduction and depression of the left eye were limited. Imaging showed a left sino-orbital tumor with mass effect on the medial rectus muscle resulting in proptosis. The lesion showed intracranial extension through the superior orbital fissure with bone erosion and sclerotic bone reaction. Endoscopic ethmoidal, maxillary, and orbital biopsies revealed an inflammatory myofibroblastic tumor. Full blood count showed an eosinophilia while antineutrophil cytoplasmic antibodies and C-reactive protein were negative. To date, 7 cases of orbital myofibroblastic tumor have been described, though none of the prior studies have described bone invasion.

Conclusions

This erosive sino-orbital inflammatory myofibroblastic tumor is a novel finding mimicking a malignant tumor.
Current Status of Visual Field Examination in Andalusia, Spain: The SICVA Study
Authors: Benítez-del-Castillo Javier , Regi Teresa , Group The Sicva Study
Published: June 2014

Purpose

To ascertain the frequency of visual field examination (VFE) in patients attending public Andalusian hospitals (the SICVA study).

Methods

This was a multicenter, observational, retrospective study of patients with documented and/or suspected glaucoma subject to campimetric monitoring for longer than 2 years. The numbers of VFEs performed in the first 2 years and in the complete follow-up period were analyzed. Data on VFE reliability were studied and VFE change was collected based on the Glaucoma Staging System 2.

Results

A total of 722 eyes (from 467 consecutive patients), 349 with suspected and 373 with documented glaucoma, were included. Mean patient age was 65.9 years (SD = 11.3), and median follow-up time was 56 months (P25 = 36, P75 = 84). Three (P25 = 2, P75 = 4) VFEs were performed in the first 2 years of follow-up in the overall sample, as compared to 2 VFEs (P25 = 2, P75 = 4) in patients with suspected glaucoma, and 3 VFEs (P25 = 2, P75 = 4) in those with documented glaucoma (p<0.001).

Conclusions

Based on these results, frequency of VFE in Andalusia differs from the standards recommended by the European Glaucoma Society to assess progression in the first 2 years of patient follow-up.
Infantile Nystagmus and Visual Deprivation: Foveal Instability and Refractive Development in a Low Vision Register Series
Authors: Fledelius Hans C. , Jensen Hanne
Published: June 2014

Purpose

To evaluate whether effects of early foveal motor instability due to infantile nystagmus might compare to those of experimental visual deprivation on refraction in a childhood series.

Methods

This was a retrospective analysis of data from the Danish Register for Blind and Weak-sighted Children with infantile nystagmus recorded as prime diagnosis. We perused 90 records of children now aged 10–17 years, some of whom eventually exceeded the register borderline of 0.3 as best-corrected visual acuity. Spherical equivalent refraction was the primary outcome parameter, but visual acuity, astigmatism, and age were further considered. The series comprised 48 children with nystagmus as single diagnosis, whereas 42 had clinical colabels (Down syndrome [ 13 ], dysmaturity [ 9 ], and mental retardation, encephalopathy [ 20 ]).

Results

Median binocular visual acuity was 0.3 in the full series, and median refraction was emmetropia in all subgroups. Compared with Danish control data, myopia was over-represented, and generally of juvenile onset. The Down syndrome subgroup was separated from the remainder by an even higher myopia prevalence. Astigmatism above 1 D cylinder value was recorded in 52% of all cases.

Conclusions

The prevalence of myopia and astigmatism was higher among children with nystagmus than in controls. Myopia was mainly juvenile, and not related to the period of infancy when the motor foveal smear is considered most disturbing and possibly influencing visual development.
Optic Nerve and Visual Pathways Primary Glioblastoma Treated with Radiotherapy and Temozolomide Chemotherapy
Authors: Caignard Angélique , Faguer Rogatien , Mercier Philippe , Menei Philippe , Milea Dan
Published: June 2014

Purpose

Primary malignant gliomas of the optic nerves are rare tumors of adulthood, progressing rapidly to blindness and to death within several months, regardless of the type of treatment. Recently, treatments associating radiotherapy and temozolomide have been used in other types of glioblastomas, but their impact on optic nerve malignant gliomas is not known.

Methods

This was a retrospective case series of 2 patients diagnosed with primary optic nerve and chiasm glioblastoma (GBM), treated with radiotherapy and concomitant temozolomide.

Results

A 74-year-old man presented with visual loss caused by an infiltrative and enhancing lesion, affecting the left optic nerve and the chiasm, subsequently confirmed as GBM World Health Organization (WHO) grade IV. The patient was treated with external conformal radiotherapy (54 Gy over 42 days) and concomitant chemotherapy with temozolomide (75 mg/m2/day), followed by 6 monthly cycles of adjuvant treatment (250 mg/day for 5 days). The second patient was a 74-year-old woman diagnosed with bilateral visual loss due to pathologically confirmed GBM (WHO grade IV). She was treated with temozolomide (220 mg/day) for 1 month, followed by radiotherapy (54 Gy over 42 days) and temozolomide chemotherapy (75 mg/m2/day). There was no adjuvant regimen. This treatment resulted in disease stabilization and partial preservation of vision during 12 months for patient 1, 8 months for patient 2. Survival after first examination was 15 and 11 months, respectively.

Conclusions

Combined radiotherapy and temozolomide may be an alternative treatment in optic nerve and visual pathways primary GBM, potentially providing a longer survival.