bluuebunny/crossref_metadata_2025 huggingface dataset:
Dry Sliding Wear Behavior of Hot Forged and Annealed Cu-Cr-SiС In Situ Composite
Authors: Gautam R.K. , Sharma Satish C. , Jain S.C. , Ray Subrata
Published: March 2013

In-situ composites offer a wide selection of constituent and an opportunity for understanding the mechanisms their mechanical properties so that intelligent decisions may be taken while tailoring a composite for a specific application. Properties of material are basically governed by the constituent phases and their distribution and depend on the composition and processing conditions. In the present investigation tribological properties of hot forged Cu-Cr-SiC and annealed after hot forging system are proposed to be studied by addition of Cr and SiC into the copper matrix. The effect of constituent phases on tribological properties after hot forged and annealed after hot forged has been investigated. It is expected to enhance the understanding of tribological properties in this presented work for the hot forged Cu-Cr-SiC composite system.
Size and Solid Solubility in Electrodeposited Ag-Ni Nanoparticles
Authors: Srivastava Chandan , Mundotiya Brij Mohan
Published: March 2013

Owing to a large difference in atomic sizes and a positive enthalpy of mixing, Ag and Ni form an immiscible system. In the current work, we report on the electrodeposition of Ag-Ni nanoparticles with a solid solution structure. Effect of current on the relative changes in composition and sizes of solid solution nanoparticles is illustrated. It is shown that with increase in the deposition current, size of Ag-Ni nanoparticles decreases due to an increased nucleation rate. With decrease in size the extent of miscibility of Ni in Ag increases due to increased energetic contribution from the particle curvature.
Cavitation and Slurry Erosion of Aluminum in the Slurry Pot Tester
Authors: Amarendra Hassan Jayaraj , Chaudhari Gajanan P. , Nath S.K.
Published: March 2013

In harnessing clean and renewable energy sources water turbines represent a significant portion of the power generation worldwide. Because of erosion, repair and maintenance of hydraulic turbines is a difficult problem. Material removal in hydraulic turbine components may occur either by particle erosion or cavitation erosion or by their combined action. Many ASTM standard and non standard test rigs are aimed at specific tests, like solid particle erosion, cavitation erosion. To simulate the real conditions in a laboratory setup, a novel method is employed to combine the effect of cavitation erosion and slurry erosion in the slurry pot tester. Triangular prismatic cavitation inducers are used in the conventional slurry pot tester. The aluminum test specimens are investigated in the slurry pot tester. A wide variation in material loss was noted under different exposure conditions. The maximum material loss is ascribed to combined effects of solid particle erosion and cavitation erosion.
A Parameter for Selection of Nano-Dispersoids in Nanofluids for Thermal Applications
Authors: Ghosh M.M. , Ghosh S. , Pabi S.K.
Published: March 2013

A model reported by the present investigators has earlier shown that the extent of heat pick up by a nanoparticle during its collision with the heat source in a given nanofluid would depend on the thermal conductivity (kp, unit W/m.K), density (ρ, unit kg/m3), elastic modulus (E, unit GPa) and Poissons ratio (μ) of the nanoparticle and heat source. Considering the expression for collision period and thermal conductivity of nanoparticle, a factor χ =kp(ρ/E)0.4 is proposed here and examined for the preliminary identification of the potential of a dispersoid in enhancing the thermal conductivity of a nanofluid. The χ-factor for Ag, Cu, CuO, Al2O3 and SiO2 are 2960, 2247, 116, 14.1 and 5.5, respectively. The higher χ-factor of CuO compared to that of Al2O3 can explain why water and ethylene glycol (EG) based CuO-nanofluid is reported to show higher enhancement in the thermal conductivity, when compared to similar Al2O3-nanofluid. The χ for SiO2 is much smaller than that for Ag, which also corroborates well with the marginal enhancement in thermal conductivity of water based nanofluid containing SiO2 nanoparticles. Therefore, a high value of χ of the nanodispersoid can serve as a parameter for the design of nanofluids for heat transfer applications.
Synthesis and Magnetic Properties of Nanocrystalline Co-Ni Alloys: A Review
Authors: Panday Sudhakar , Jeevanandam P. , Daniel B.S. Sunder
Published: March 2013

This review article deals with the synthesis, characterization and magnetic properties of Co-Ni nanoalloys. The various physical and chemical methods for the synthesis of Co-Ni alloy nanoparticles are discussed. Co-Ni alloy nanoparticles with different size and shape such as spherical, rods, wires chain-like assembly are found to depend on the synthesis method and experimental condition. The structure of Co-Ni alloys is eitherfcc,hcpor mixedfccandhcpphase and found to depends on size, shape and concentration of Co in the Co-Ni alloys. Sodium hydroxide (NaOH) concentration and Co to Ni ratio influence the shape of bimetallic Co-Ni nanoparticles. Pt nucleating agents produced smaller size of Co-Ni alloy particles compared to Ru and Ag. Higher Co concentration in the Co-Ni alloys also influences the size alloy particles. The magnetic properties of Co-Ni nanoalloys depend on the size, shape and composition of the binary alloys. Surface oxidation of Co-Ni alloy nanoparticles decrease the saturation magnetization and increases with Co concentration in the alloys. The shape of Co-Ni alloy nanoparticles has an influence on coercivity. The microwave absorption properties of the Co-Ni alloys found to depend on the shape, size and composition of the binary alloys. The absorbance peaks shifts to higher frequency with decrease in size of the alloy particles. Potential applications of Co-Ni alloys in various fields are highlighted.
Organic Electronics: Successes in Organic Light Emitting Diodes and Display Technology
Authors: Deepak
Published: March 2013

Whereas single crystal silicon limited to 300 mm in diameter dominates the bulk of electronic devices, when electronics is required on a larger scale we have to rely on either amorphous or multi-crystalline materials. In this category, the organic semiconductors have made rapid in-roads. Among their applications, most notable successes are organic light emitting diodes (OLEDs) based displays. But, these OLEDs could also be made to emit in ultraviolet (UV) as shown through polysilanes devices. Two materials that we have investigated emit in UV or near UV. The emission spectrum could be manipulated by modifying the side groups on the main Si chain. Further discussed in the paper are full colour passive matrix displays we have made and development of thin films transistor for moving towards active matrix displays.
Inkjet Printed Organic Thin Film Transistors: Achievements and Challenges
Authors: Mandal Saumen , Purohit Gangadhar , Katiyar Monica
Published: March 2013

Inkjet printing of organic thin film transistors is an enabling technology for many applications requiring low cost electronics such as RFID tags, sensors, e-paper, and displays. This review summarizes the achievements and remaining challendges in the field. An all inkjet printed organic thin film transistor is feasible, but manufacturability needs to be improved. Often, a hybrid process in which only some layers are inkjet printed is used. Development of devices requires optimization of (1) ink chemistry, (2) inkjet process, (3) substrate ink interaction, and (4) new device structures. Several conducting, dielectric and semiconducting materials have been used to formulate ink. It appears that metal nanoparticle based conducting ink and PEDOT:PSS are widely used materials to fabricate source, drain and gate electrodes. PVPh is the most popular dielectric material for inkjet printing. To print semiconducting layer, both polymers and oligomers/small molecules are used. Many high performance organic semiconductors are p-type, but few n-type organic semiconductors show excellent performance. In addition to improved materials, challenges inherent in the inkjet process also need solutions. These are registration, alignment of the source,and drain with gate, resolution, reducing off-state current, and roll-to-roll processing.
Studies on Electroless Coatings at IIT Roorkee - A Brief Review
Authors: Makkar Preeti , Agarwala Ramesh Chandra , Agarwala Vijaya
Published: March 2013

Since the introduction of Electroless (EL) coating in 1946 by Brenner and Riddle, the process has been the subject of steady growth. It is one of the most elegant methods available for the production of alloy coatings on surface. The technique involves the autocatalytic reduction, at the substrate/solution interface, of cations by EL bath released from suitable chemical reducing agents. EL coating technique is simple one, as can be manifested just by controlling pH and temperature of the coating bath. Such coatings are reported to provide excellent physical and mechanical properties. The electroless coatings are being studied at Indian Institute of Technology Roorkee since 1985. The structural and morphological behavior of Ni-P coatings for different phosphorous contents has been extensively studied. Sub-micron size coating islands and their transformations have been deduced. The metallography studies using hot stage within TEM to follow the phase transformations occurring at various temperatures have been studied for Ni-B EL coatings. The realization of mechanical bonding along with chemical bonding between EL coating and the substrate has been explained by coated copper on ceramic powder. As a forward step towards composite coatings, Ni-P-C, Ni-P-Al2O3, Ni-P-ZrO2has been developed by EL co-deposition technique. Ag-graphite coatings produced by EL technique exhibits nearly five times higher wear resistance and nearly two times better corrosion resistance apart from a good electrical conductor. The tribological behavior of electroless Ni-P-X and Ni-P coatings on steel and aluminium substrates in different conditions i.e., as coated, heat treated at various temperatures at different extents of time with different normal loads, have been studied in terms of dry sliding friction and wear against counter face of case hardened steel. In Ni-P-X nanocoating (X= ZrO2-Al2O3-Al3Zr), X has been producedin-situand are of nanosize particles. Such coating could be done on carbon fibre of 7µ diameter uniformly. Ni-P-ferrite nanocoatings with thickness less than nearly 1mm thick, is exhibiting good absorption of microwave in the range of 12-18 GHz which can be exploited for radar applications. Micro-thickness coatings are paying ways to nanocoatings. Nanocoatings are the coatings in which either the thickness of the coating is in nanolevel or second phase that dispersed in the coat matrix is of nanosize. To further explore the field of EL nanocomposite coatings, now days, a work on EL Ni-P-ZnO, TiO2, Al2O3, ZrO2and Ni-B-ZrO2for its mechanical properties has been carried out.
Microstructural Characterization and Cyclic Oxidation Behavior of HVOF-Sprayed Cr3C2-NiCr Coating on Boiler Steel at Elevated Temperature
Authors: Shukla V.N. , Jayaganthan R. , Tewari V.K.
Published: March 2013

The oxidation behavior of HVOF sprayed Cr3C2NiCr coatings on 310S stainless steel for 50 cycles in air at 700°C under cyclic conditions has been investigated in the present work. The microstructure, hardness and porosity of the coating were characterised. X-ray diffraction, field emission scanning electron microscope with energy dispersive spectroscopy and X-ray mapping were used to analyze the scales formed on the surface of the oxidised samples. The microstructure of the as sprayed coating showed uniformly distributed chrome carbide-rich ceramic grains attached with nickel chrome-rich binder phase. The Cr3C2-25% NiCr coated specimen exihibit negligible microspalling of the scales upon oxidation. The improved oxidation resistance of Cr3C2NiCr coatings may be attributed to the formation of oxides of chromium, nickel, and spinels of nickel and chromium.
Texture Effects in the Delithiation of Lithium Cobalt Oxide
Authors: Basch Angelika , de Campo Liliana , Albering Jörg H. , White John W.
Published: March 2013

The effects of aqueous delithiation of lithium cobalt oxide crystals on the crystal texture and etching patterns has been studied by electron microscopy, x-ray and neutron diffraction at high resolution. The delithiation proceeds to exfoliation and in the process textural patterns that appear have been associated with periodic strains in the crystals developed by the delithiation.
Modification in Texture of Magnesium by the Addition of Rare Earth Elements and its Influence on Mechanical Properties
Authors: Suresh Murugavel , Suwas Satyam
Published: March 2013

Mg alloys show limited room temperature formability compared to its lightweight counterpart aluminium alloys, which is a main obstacle in using this metal for most of the structural applications. However, it is known that grain refinement and texture control are the two possibilities for the improvement of formability of magnesium alloys. Amongst the approaches attempted for the texture weakening, additions through of rare-earth (RE) elements have been found most effective. The relationship between the texture and ductility is well established. In this paper, the effect of rare earth addition on texture weakening has been summarized for various magnesium alloys under the two most common modes of deformation methods.
Looking Back
Authors: Ray Subrata
Published: March 2013

My entry to the professional world of academics was more of straying into it when I had been trying to find a suitable profession where I could spend my life without boredom. Continuing studies till Ph.D. was partly due to inertia and partly due to the enjoyment of a carefree student life. After completing Ph.D. only two options were available – joining research laboratories or higher academic institutions of teaching and research. Initially, I joined research laboratories and soon I was tired of listening everyday to the frustrations of my colleagues and their dissatisfaction with their bosses. The possibility of spending my life in such an environment started to haunt me and I was afraid to become one of them eventually. I decided to jump out of it and join the academic world of higher education. I got fascinated by this environment, which has an ever-changing component of student community, which helps one to remain young in mind. The academic world also has its share of negativities. But one has the freedom of creating an insulated space where you may do your academic work happily along with your students and collaborators and build a barrier outside
Molecule Induced Strong Coupling between Ferromagnetic Electrodes of a Molecular Spintronics Device
Authors: Tyagi Pawan
Published: March 2013

Utilizing molecules for tailoring the exchange coupling strength between ferromagnetic electrodes can produce novel metamaterials and molecular spintronics devices (MSD). A practical way to produce such MSD is to connect the molecular channels to the electrodes of a magnetic tunnel junction (MTJ). This paper discusses the dramatic changes in the properties of MTJ testbed of a MSD due to molecular device elements with a net spin state. When organometallic molecular complexes (OMCs) were bridged across the insulator along the exposed side edges, a MTJ testbed exhibited entirely different magnetic response in magnetization, ferromagnetic resonance and magnetic force microscopy studies. OMCs only affected the ferromagnetic material when it was serving as the electrode of a tunnel junction. Molecule produced the strongest effect on the MTJ with electrodes of dissimilar magnetic hardness. This study encourages the validation of this work and exploration of similar observations with the other combinations MTJs and molecules, like single molecular magnet, porphyrin, and molecular clusters.
Challenges in Manufacturing Aluminium Based Metal Matrix Nanocomposites via Stir Casting Route
Authors: Chatterjee Subhranshu , Mallick Amitava Basu
Published: March 2013

The influence of material processing conditions for preparing aluminium based metal matrix nanocomposites through stir casting route is reviewed. The role of particle size with respect to Brownian motion, Stokes settling velocity and strengthening mechanism is assessed from theoretical understandings. Variation of microstructural features and mechanical properties of the nanocomposites are predicted from theoretical concepts and related mathematical models. Experiments conducted to validate the theoretical predictions show that both Orowan and grain refinement strengthening mechanisms remain operative which is the key to the improved strength property of the nanocomposites.
Fabrication and Characterisation of Al-Al2O3 Composite by Mechanical Alloying
Authors: Gautam R.K. , Mohan Anita , Mohan Sunil
Published: March 2013

Over the years, Aluminium Matrix Composites (AMCs) have gained importance in numerous structural, non-structural and functional applications in different engineering sectors. Driving force for the utilisation of AMCs in these sectors include performance, economics and environmental benefits. The key benefit of AMCs in transportation sector is lower fuel consumption. Particulate reinforced Aluminium Matrix Composites have been successfully used in automotive and aerospace industry due to their light weight, high strength to weight ratio and good wear resistance.This work is focussed on the study of the influence of different composition of reinforcement (Al2O3) on physical and mechanical behaviour of Aluminium Matrix Composites. These AMCs will be fabricated by mechanical alloying. In this study instead of aluminium powder aluminium chips will be used along with Al2O3powder with that it is expected that embedment of particles will be better and porosity will be minimised. Once compact are ready these will be sintered and will be evaluated for its various physical, microstructural and mechanical properties.
Multifunctional Mesoporous Nanocomposites
Authors: Banerjee Shilpi , Chakravorty Dipankar
Published: March 2013

Multifunctional behaviour viz., ferroelectric, ferromagnetic and magnetodielectric coupling has been reported in a number of nanocomposites. The latter were synthesized by growing nanoparticles of different kinds within a suitable matrix. Different morphologies of the particles were introduced. Both natural as well as synthetic mesoporous materials were used to prepare nanocomposite systems. Mesoporous structures with large surface areas and pore volumes were found to be effective in developing most efficient drug delivery systems. For identical reasons such structures were suitable as catalysts in various industrially important reaction processes, as humidity and gas sensors, as magnetic sensors. Mesoporous carbon based nanocomposites used as electrodes were found to improve the efficiency of lithium-ion batteries. Nanocomposites using mesoporous carbon and carbon nanotubes were shown to improve the performance of dye sensitized solar cells. In this article, the above mentioned developments are reviewed and discussed.
Design of Synthetic Genetic Oscillators Using Evolutionary Optimization
Authors: Chang Yen-Chang , Lin Chun-Liang , Jennawasin Tanagorn
Published: March 2013

Efforts have been made to establish computer models of genetic oscillation. We have developed a real structured genetic algorithm (RSGA) which combines advantages of the traditional real genetic algorithm (RGA) with those of the structured genetic algorithm (SGA) and applies it as an optimization strategy for genetic oscillator design. For the generalized design, our proposed approach fulfils all types of genes by minimizing the order of oscillator while searching for the optimal network parameters. The design approach is shown to be capable of yielding genetic oscillators with a simpler structure while possessing satisfactory oscillating behavior. In silico experiments show effectiveness of the proposed algorithm to genetic oscillator design. In particular, it is shown that the proposed approach performs better than the traditional GAs in the sense that a cheaper structure of genetic oscillators can be obtained.
EDGE-pro: Estimated Degree of Gene Expression in Prokaryotic Genomes
Authors: Magoc Tanja , Wood Derrick , Salzberg' Steven L.
Published: March 2013

Background

The expression levels of bacterial genes can be measured directly using next-generation sequencing (NGS) methods, offering much greater sensitivity and accuracy than earlier, microarray-based methods. Most bioinformatics software for estimating levels of gene expression from NGS data has been designed for eukaryotic genomes, with algorithms focusing particularly on detection of splicing patterns. These methods do not perform well on bacterial genomes.

Results

Here we describe the first software system designed explicitly for quantifying the degree of gene expression in bacteria and other prokaryotes. EDGE-pro (Estimated Degree of Gene Expression in PROkaryotes) processes the raw data from an RNA-seq experiment on a bacterial or archaeal species and produces estimates of the expression levels for each gene in these gene-dense genomes.

Software

The EDGE-pro tool is implemented as a pipeline of C++ and Perl programs and is freely available as open-source code at http://www.genomics.jhu.edu/software/EDGE/index.shtml .
Loss of Imprinting of IGF2 Gene in the Chorionic Tissues of Spontaneously Eliminated Human Embryos
Authors: Zastavna Danuta , Makukh Halyna , Tretjak Bogdan , Bilevych Olena , Tyrka Miroslaw
Published: March 2013

Insulin-like growth factor-2 (IGF-2) is a mitogen, growth and differentiation modulator for many cell types. It is mainly expressed during the prenatal development, and its activity strongly depends on the genomic imprinting. Genomic imprinting in the chorionic tissues of spontaneously eliminated human embryos has been studied on the model of 820-AG (Apa1) of the IGF-2 gene locus. Molecular and genetic analysis was performed on the polymorphic 820-AG IGF2 locus in 107 samples of DNA extracted from the chorionic tissues of spontaneously eliminated human embryos within 5–10 weeks of gestation. Presence of AG genotype Apa 1 single nucleotide polymorphisms of the IGF-2 was shown to cause more than a 7-fold increase in the risk of embryo elimination. Thus, the loss of genomic imprinting of the IGF-2 gene may be an important cause of the miscarriages in human.
Transfert du pseudo-coefficient de Kottwitz et formules de caractère pour la série discrète de GL(N) sur un corps local
Authors: Broussous P.
Published: March 2013

Soit G le groupe GL(N, F), où F est un corps localement compact et non archimédien. En utilisant la théorie des types simples de Bushnell et Kutzko, ainsi qu'une idée originale d'Henniart, nous construisons des pseudo-coefficients explicites pour les représentations de la série discrète de G. Comme application, nous en déduisons des formules inédites pour la valeur du charactère d'Harish- Chandra de certaines telles représentations en certainséléments elliptiques réguliers.
About "Bulky" Links, generated by Generalized Möbius Listing's bodies $GML^{n}_{3}$
Authors: Tavkhelidze I. , Cassisa C. , Gielis Johan , Ricci Paolo E.
Published: March 2013

In the present paper we consider the "bulky knots'' and "bulky links'', which appear after cutting a Generalized Möbius Listing's

GML_3^n

body (whose radial cross section is a plane

3

-symmetric figure with three vertices) along different Generalized Möbius Listing's surfaces

GML_2^n

situated in it. This article is aimed to investigate the number and geometric structure of the independent objects appearing after such a cutting process of

GML_3^n

bodies. In most cases we are able to count the indices of the resulting mathematical objects according to the known tabulation for Knots and Links of small complexity.
Mean winds, SAO and QBO in the stratosphere, mesosphere and lower thermosphere over Ascension Island (8° S 14° W)
Authors: Day K. A. , Mitchell N. J.
Published: March 2013

Abstract. Mean winds in the mesosphere and lower thermosphere (MLT) over Ascension Island (8° S and 14° W) have been investigated using meteor radar wind observations. The results presented in this study are from the interval October 2001 to December 2011. There is a clear annual oscillation in the monthly-mean meridional winds. The monthly-mean meridional winds observed over Ascension Island at meteor heights are found to be southward during April–October, reaching velocities up to about −23 m s−1 and northward the rest of the year, reaching velocities up to about 16 m s−1. The monthly-mean zonal winds are generally westward through most of the year, reaching velocities up to about −46 m s−1. However, there are eastward winds in May–August and again in December in the lower heights that the radar observes. These winds maximises at heights of about 86 km reaching velocities up to about 36 m s−1 and decays quickly above and below. The Mesospheric Semi-Annual Oscillation (MSAO) is clearly observed in the monthly-mean zonal winds. The first westward phase of the winds is much stronger than the second. The first westward phase of the MSAO was found to maximise at heights of about 84 km and to in general reach amplitudes of about −35 m s−1. We have compared the HWM-07 model to our observations. Our observed meridional winds are generally more southward than those of the model at meteor heights in the southern hemispheric winter, whereas HWM-07 suggests that in this season only weakly southward, or even northward flows occur at the lower heights. The zonal monthly-mean winds are in general agreement but somewhat less westward than observed by the radar. In one of the eight events in which the first westward phase of the MSAO was observed, the strongest westward winds reached about −75 m s−1, compared to the mean of about −35 m s−1 for other events. We explain this observation in terms of a mechanism which has been previously proposed by others. In this the relative phasing of the Stratospheric Quasi-Biennial Oscillation (SQBO) and the MSAO allow an unusually large flux of gravity waves with westward phase speed to reach the mesosphere. The dissipation of these waves then drives the MLT winds to large westward velocities. We demonstrate that the necessary phase relationship existed during the event we observed in 2002 and not during other times. This provides strong support for the suggestion that those extremes in zonal flow are a~result of modulated gravity-wave fluxes.
Causes of variation in soil carbon simulations from CMIP5 Earth system models and comparison with observations
Authors: Todd-Brown K. E. O. , Randerson J. T. , Post W. M. , Hoffman F. M. , Tarnocai C. , Schuur E. A. G. , Allison S. D.
Published: March 2013

Abstract. Stocks of soil organic carbon represent a large component of the carbon cycle that may participate in climate change feedbacks, particularly on decadal and centennial timescales. For Earth system models (ESMs), the ability to accurately represent the global distribution of existing soil carbon stocks is a prerequisite for accurately predicting future carbon–climate feedbacks. We compared soil carbon simulations from 11 model centers to empirical data from the Harmonized World Soil Database (HWSD) and the Northern Circumpolar Soil Carbon Database (NCSCD). Model estimates of global soil carbon stocks ranged from 510 to 3040 Pg C, compared to an estimate of 1260 Pg C (with a 95% confidence interval of 890–1660 Pg C) from the HWSD. Model simulations for the high northern latitudes fell between 60 and 820 Pg C, compared to 500 Pg C (with a 95% confidence interval of 380–620 Pg C) for the NCSCD and 290 Pg C for the HWSD. Global soil carbon varied 5.9 fold across models in response to a 2.6-fold variation in global net primary productivity (NPP) and a 3.6-fold variation in global soil carbon turnover times. Model–data agreement was moderate at the biome level (R2 values ranged from 0.38 to 0.97 with a mean of 0.75); however, the spatial distribution of soil carbon simulated by the ESMs at the 1° scale was not well correlated with the HWSD (Pearson correlation coefficients less than 0.4 and root mean square errors from 9.4 to 20.8 kg C m−2). In northern latitudes where the two data sets overlapped, agreement between the HWSD and the NCSCD was poor (Pearson correlation coefficient 0.33), indicating uncertainty in empirical estimates of soil carbon. We found that a reduced complexity model dependent on NPP and soil temperature explained much of the 1° spatial variation in soil carbon within most ESMs (R2 values between 0.62 and 0.93 for 9 of 11 model centers). However, the same reduced complexity model only explained 10% of the spatial variation in HWSD soil carbon when driven by observations of NPP and temperature, implying that other drivers or processes may be more important in explaining observed soil carbon distributions. The reduced complexity model also showed that differences in simulated soil carbon across ESMs were driven by differences in simulated NPP and the parameterization of soil heterotrophic respiration (inter-model R2 = 0.93), not by structural differences between the models. Overall, our results suggest that despite fair global-scale agreement with observational data and moderate agreement at the biome scale, most ESMs cannot reproduce grid-scale variation in soil carbon and may be missing key processes. Future work should focus on improving the simulation of driving variables for soil carbon stocks and modifying model structures to include additional processes.
Root growth of Lotus corniculatus interacts with P distribution in young sandy soil
Authors: Felderer B. , Boldt-Burisch K. M. , Schneider B. U. , Hüttl R. F. J. , Schulin R.
Published: March 2013

Abstract. Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P) is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils, as they only depend on atmospheric nitrogen (N) fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites, the experimental Chicken Creek Catchment (CCC) in eastern Germany and a nearby experimental site (ES) with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition, we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5 × 10 cm) with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P concentrations. In the high-density samplings, we excavated soil-cubes of 10 × 10 × 10 cm size from the topsoil of 3 mini-plot areas (50 × 50 cm) each on the ES and the CCC on which L. corniculatus had been planted (ES) or occurred spontaneously (CCC) and for each cube separated the soil attached to the roots (root-adjacent soil) from the remaining soil (root-distant soil). Root length density was negatively correlated with labile P (resin-extractable P) in the root-distant soil of the CCC plots and with water-soluble P in the root-distant soil of the ES plots. The results suggest that P depletion by root uptake during plant growth soon overrode the effect of preferential root allocation in the relationship between root density and plant-available soil P heterogeneity.
A fertile peatland forest does not constitute a major greenhouse gas sink
Authors: Meyer A. , Tarvainen L. , Nousratpour A. , Björk R. G. , Ernfors M. , Kasimir Klemedtsson Å. , Lindroth A. , Räntfors M. , Rütting T. , Wallin G. , Weslien P. , Klemedtsson L.
Published: March 2013

Abstract. Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with a high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we determined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied: for the year 2008, direct (eddy covariance) and an indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.2 (± 1.7)t C ha–1yr–1 due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was in its optimum growth phase. N2O fluxes were determined by the closed chamber technique and amounted to 3.3 (± 2.4) t CO2eq ha–1 yr–1. According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of −4.1 (± 2.6) t CO2eq ha–1 yr–1. This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 3.3 (± 10.1)t CO2eq ha–1 yr–1. Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to major uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the site was in its optimum growth stage, i.e. the rate of C sequestration was at its maximum and will decrease with forest age, it will probably become a GHG source once again as the trees mature. Since forests in their younger stages are usually GHG sources or have no effect on GHGs, the overall sink potential of this afforested nutrient-rich organic soil is probably limited to only a short period.
Future Flows Hydrology: an ensemble of daily river flow and monthly groundwater levels for use for climate change impact assessment across Great Britain
Authors: Prudhomme C. , Haxton T. , Crooks S. , Jackson C. , Barkwith A. , Williamson J. , Kelvin J. , Mackay J. , Wang L. , Young A. , Watts G.
Published: March 2013

Abstract. The dataset Future Flows Hydrology was developed as part of the project "Future Flows and Groundwater Levels'' to provide a consistent set of transient daily river flow and monthly groundwater level projections across England, Wales and Scotland to enable the investigation of the role of climate variability on river flow and groundwater levels nationally and how this may change in the future. Future Flows Hydrology is derived from Future Flows Climate, a national ensemble projection derived from the Hadley Centre's ensemble projection HadRM3-PPE to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications. Three hydrological models and one groundwater level model were used to derive Future Flows Hydrology, with 30 river sites simulated by two hydrological models to enable assessment of hydrological modelling uncertainty in studying the impact of climate change on the hydrology. Future Flows Hydrology contains an 11-member ensemble of transient projections from January 1951 to December 2098, each associated with a single realisation from a different variant of HadRM3 and a single hydrological model. Daily river flows are provided for 281 river catchments and monthly groundwater levels at 24 boreholes as .csv files containing all 11 ensemble members. When separate simulations are done with two hydrological models, two separate .csv files are provided. Because of potential biases in the climate–hydrology modelling chain, catchment fact sheets are associated with each ensemble. These contain information on the uncertainty associated with the hydrological modelling when driven using observed climate and Future Flows Climate for a period representative of the reference time slice 1961–1990 as described by key hydrological statistics. Graphs of projected changes for selected hydrological indicators are also provided for the 2050s time slice. Limitations associated with the dataset are provided, along with practical recommendation of use. Future Flows Hydrology is freely available for non-commercial use under certain licensing conditions. For each study site, catchment averages of daily precipitation and monthly potential evapotranspiration, used to drive the hydrological models, are made available, so that hydrological modelling uncertainty under climate change conditions can be explored further. doi:10.5285/f3723162-4fed-4d9d-92c6-dd17412fa37b
Global hydrobelts and hydroregions: improved reporting scale for water-related issues?
Authors: Meybeck M. , Kummu M. , Dürr H. H.
Published: March 2013

Abstract. Global-scale water issues such as its availability, water needs or stress, or management, are mapped at various resolutions and reported at many scales, mostly along political or continental boundaries. As such, they ignore the fundamental heterogeneity of hydroclimates and natural boundaries of river basins. Here we describe the continental landmasses at two levels: eight hydrobelts strictly limited by river basins, defined at a 30' (0.5°) resolution, which are decomposed on continents as 26 hydroregions. The belts were defined and delineated, based primarily on the annual average temperature (T) and run-off (q), to maximise inter-belt differences and minimise intra-belt variability. This new global puzzle defines homogeneous and near-contiguous entities with similar hydrological and thermal regimes, glacial and postglacial basin histories, endorheism distribution and sensitivity to climate variations. The mid-latitude, dry and subtropical belts have northern and southern analogues and a general symmetry can be observed for T and q between them. The boreal and equatorial belts are unique. Population density between belts and between the continents varies greatly, resulting in pronounced differences between the belts with analogues in both hemispheres. Hydroregions (median size 4.7 M km2) are highly contrasted, with the average q ranging between 6 and 1393 mm yr−1 and the average T between −9.7 and +26.3 °C, and a population density ranging from 0.7 to 0.8 p km−2 for the North American boreal region and some Australian hydroregions to 280 p km−2 for some Asian hydroregions. The population/run-off ratio, normalised to a reference pristine region, is used to map and quantify the global population at risk of severe water quality degradation. Our initial tests suggest that hydrobelt and hydroregion divisions are often more appropriate than conventional continental or political divisions for the global analysis of river basins within the Earth system and of water resources. The GIS files of the hydrobelts and hydroregions are available at the supplement of this article and at doi:10.1594/PANGAEA.806957 as well as geotypes.net.
Statistical modelling of the snow depth distribution on the catchment scale
Authors: Grünewald T. , Stötter J. , Pomeroy J. W. , Dadic R. , Moreno Baños I. , Marturià J. , Spross M. , Hopkinson C. , Burlando P. , Lehning M.
Published: March 2013

Abstract. The spatial distribution of alpine snow covers is characterized by a large variability. Taking this variability into account is important for many tasks including hydrology, glaciology, ecology or natural hazards. Statistical modelling is frequently applied to assess the spatial variability of the snow cover. For this study, we assembled seven data sets of high-resolution snow-depth measurements from different mountain regions around the world. All data were obtained from airborne laser scanning near the time of maximum seasonal snow accumulation. Topographic parameters were used to model the snow depth distribution on the catchment-scale by applying multiple linear regressions. We found that by averaging out the substantial spatial heterogeneity at the metre scales, i.e. individual drifts and aggregating snow accumulation at the landscape or hydrological response unit scale, that 30% to 91% of the snow depth variability can be explained by models that are calibrated to local conditions at the single study areas. As all sites were sparsely vegetated, only a few topographic variables were included as explanatory variables, including elevation, slope, the deviation of the aspect from north (northing), and a wind sheltering parameter. In most cases, elevation, slope and northing are very good predictors of snow distribution. A comparison of the models showed that importance of parameters and their coefficients differed among the catchments. A "global" model, combining all the data from all areas investigated, could still explain 23% of the variability. It appears that local statistical models cannot be transferred to different regions. However, there seem to be some temporal transferability, in which models developed on one peak snow season were good predictors for other peak snow seasons.
Potential surface temperature and shallow groundwater temperature response to climate change: an example from a small forested catchment in east-central New Brunswick (Canada)
Authors: Kurylyk B. L. , Bourque C. P.-A. , MacQuarrie K. T. B.
Published: March 2013

Abstract. Global climate models project significant changes to the air temperature and precipitation regimes in some regions of the Northern Hemisphere. These meteorological changes will have associated impacts to the surface and shallow subsurface thermal regimes, which are of interest to practitioners and researchers in many disciplines of the natural sciences. For example, groundwater temperature is critical for providing and sustaining suitable thermal habitat for cold-water salmonids. To investigate the surface and subsurface thermal effects of atmospheric climate change, seven downscaled climate scenarios (2046–2065) for a small forested catchment in New Brunswick, Canada were employed to drive the surface energy and moisture flux model, ForHyM2. Results from these seven simulations indicate that climate change-induced increases in air temperature and changes in snow cover could increase summer surface temperatures (range −0.30 to +3.49 °C, mean +1.49 °C), but decrease winter surface temperatures (range −1.12 to +0.08 °C, mean −0.53 °C) compared to the reference period simulation. Thus, changes to the timing and duration of snow cover will likely decouple changes in average annual air temperature (mean +2.11 °C) and average annual ground surface temperature (mean +1.06 °C). The projected surface temperature data were then used to drive an empirical surface to groundwater temperature transfer function developed from measured surface temperature and depth-dependent groundwater temperature. Results from the empirical transfer function indicated that the change in groundwater temperature will exhibit seasonality at shallow depths (1.5 m), but be seasonally constant and approximately equivalent to the change in the mean annual surface temperature at deeper depths (8.75 m). The increases in future groundwater temperature suggest that the thermal sensitivity of baseflow-dominated stream to decadal climate change may be greater than previous studies have indicated. The ecological significance of these findings is discussed.
Efficient selective filtering of seismic data using multiscale decomposition
Authors: Leite F. E. A. , Henriques M. V. C. , Gurgel V. C. , Filho J. M. S.
Published: March 2013

Abstract. Seismic signal processing is an important task in geophysics sounding and represents a permanent challenge in petroleum exploration. Although seismograms could in principle give us a picture of a geological structure, they are very contaminated by spurious signals and the ground roll noise is a strongly undesired signal present in the seismograms – it does not carry physical information about the deep geological structures. This fact demands a big effort in developing new filtering methodologies. Using discrete wavelet transform, an efficient filtering for suppression of the ground roll is presented. In this method, seismic data is decomposed in multiple scales. We can remove the noise as a surgical operation in each scale, just from the regions where they are present or strong, allowing us to preserve the maximum of relevant information.
Sensitivity of Sea Surface Temperature Simulation by an Ocean Model to the Resolution of the Meteorological Forcing
Authors: Chen F. , Shapiro G. , Thain R.
Published: March 2013

The effect on sea surface temperature (SST) predictions caused by varying atmospheric forcing within an ocean model is examined in the Celtic Sea, a typical shelf sea situated to the southwest of the British Isles. We use the 3D ocean circulation model POLCOMS, with 2 km resolution, 30 vertical layers, and two sets of meteorological forcing, at low (1.6°) and high (0.11°) horizontal resolutions. The model is validated against in situ and satellite observations. Comparisons made for the year 2008 show that increasing the resolution of the meteorological forcing does not necessarily lead to more accurate results in the modelled SST. The discrepancy between the low and high resolution cases was found to be the greatest in the summer, with the errors of the mean SST being 0.15°C and 1.15°C, respectively. Overall, the most accurate reproduction of SST throughout the year is obtained using the low resolution atmospheric data. We show that this is due not to the resolution of the forcing per se, but to the differences between the meteorological models in mean values of parameters such as cloud cover, which in turn reduce the solar radiation flux reaching the sea surface in the oceanographic model.
Projected U.S. water use likely to increase as climate warms
Authors: Balcerak Ernie
Published: March 2013

Despite increases in efficiency, water demand in the United States is likely to increase substantially in the future if climate continues to warm, new projections indicate. Brown et al. project future water use to 2090 based on past trends from U.S. Geological Survey water use data from 1960 to 2005 and trends in efficiency. They projected U.S. water demand under climate change scenarios using three different global circulation models, and they ran each model for three different global socioeconomic scenarios adapted from the scenarios used by the Intergovernmental Panel on Climate Change (IPCC).