bluuebunny/crossref_metadata_2025 huggingface dataset:
Pore Characterisation in Monodisperse Granular Assemblies
Authors: Sufian Adnan , Russell Adrian R. , Whittle Andrew J. , Saadatfar Mohammad
Published: July 2016

The micro-scale geometric arrangement of pores was quantitatively characterised for monodisperse granular assemblies, particularly in relation to pore volume distribution and pore orientation characteristics. Using physical experiments and numerical simulations, the pore volume distribution was uniquely described by the analytical k-gamma distribution function [1-2]. A pore orientation tensor was defined to determine the preferred orientation of individual pores. This was subsequently used to define a global orientation tensor that revealed an isotropic pore network for the monodisperse granular assemblies considered in this study. The global orientation tensor was analytically linked to the parameters defining the pore volume distribution.
Smoothed Particle Hydrodynamics into the Fluid Dynamics of Classical Problems
Authors: Korzani Maziar Gholami , Galindo Torres S. , Scheuermann Alexander , Williams David J.
Published: July 2016

The study concerns the application of the Smoothed Particle Hydrodynamics (SPH) method within the computational fluid dynamics (CFD). In the present study, some classical problems – the Poiseuille flow, the Hagen-Poiseuille flow, and the Couette flow – with the analytical solutions were investigated to verify a newly developed code of SPH. The code used for solving these problems, is an entirely parallel SPH solver in 3D and has been developed by the authors. Fluid was modelled as a viscous liquid with weak compressibility. The boundary walls were simulated with a special set of fixed boundary particles, and no-slip boundary condition was considered. Computational results were compared to available analytical solutions for transient hydraulic processes. Good agreement is achieved for the whole transient stage of the considered problems until steady state is reached. The results of this study highlight the potential of SPH to tackle a broad range of problems in fluid mechanics.
Random Lattice Modeling of Quasi-Brittle Fracture in Cementitious Materials: A State of the Art
Authors: Fascetti Alessandro , Bolander John E. , Nisticò Nicola
Published: July 2016

Lattice models established themselves as a powerful tool to simulate fracture processes in cementitious materials such as concrete. The paper presents the main features of this method, together with the advancements in the modeling of fracture of concrete materials. A historical perspective is also given, highlighting advantages and drawbacks of the existing fracture mechanics theories and numerical methods.
Analysis of the Effects of Mortar Thickness and Wall Building Technique in Masonry Structures Using an Anisotropic Model
Authors: Kimence Bahattin , Demirkan Samed , Ergun Hale
Published: July 2016

The aim of this study is to investigate the effect of mortar/unit thickness ratio and unit configuration on the masonry wall behaviour and on masonry structure modelling. Firstly, five wall models with different mortar/unit thickness ratios and with different sizes of units are micro-modelled by using SAP2000 software. The results of these walls are used to obtain the material properties of anisotropic macro-models in vertical and horizontal directions. Secondly, a sample unreinforced masonry structure is simulated by the same software using anisotropic material properties. Earthquake loading is applied following the Turkish seismic code. Responses of these five structure models are compared with each other and also with their isotropic modelled counterparts. It is observed that isotropic modelling overestimates the rigidity of the structure around 3-5% for low mortar/unit thickness ratios, but underestimates the rigidity around 5-7% for high mortar/unit thickness ratios
The Comparison and Analysis of Void Fraction of OGFC-13 Asphalt Concrete through Vacuum Method and Volume Method
Authors: Tang Cheng Yang , Yi Wen , He Xian Feng , Tan Li
Published: July 2016

In this paper, the mixture ratio experiment has been done about OGFC-13 asphalt mixture of the layer on S103(liuyang section) of Changsha, Hunan province The void fraction of asphalt mixture is determined by vacuum sealing method and volume method on the condition of different material and different gradation. Through the comparison and analysis of void fraction determined values by vacuum method and volume method, it can been found that the air porosity of OGFC-13 asphalt mixture has a good linear relationship with the 2.36mm pass rate. The linear relationship of void fraction determined value by vacuum method and volume method relates with materials and nominal diameter.
An Innovative Dual System for New Structures or for the Retrofit of Precast Concrete Industrial Buildings
Authors: Latour Massimo , Paolillo Marilena , Rizzano Gianvittorio , Vergato Mariacristina
Published: July 2016

In this work, the possibility to improve the seismic behaviour of precast concrete buildings is examined by proposing the adoption of a dual system composed by the internal pendular columns of the building and the external cladding walls. To this scope, it is suggested to substitute the joints classically adopted at the top of the panels with a connection able to work as a slider with vertical axis and to insert at the bottom of the walls two or more hysteretic dampers working on the uplift of the cladding panels occurring under seismic actions. With this approach, with respect to the classical design philosophy, due to the participation of the cladding panels, the structure is stiffened, obtaining a reduction of the lateral drifts under serviceability limit states, and its seismic behavior is improved due to the additional source of energy dissipation represented by the dampers located at the base of the walls. The effectiveness of the suggested approach is verified on a case study designed following the proposed approach.
An Innovative Approach to Assess Seismic Safety of Historical Centres
Authors: Vanzi Ivo , Biondi Samuele , Cataldo Nicola , Sulpizio Concetta
Published: July 2016

The present paper describes the activities carried out at Chieti-Pescara University after the 2009 L'Aquila Earthquake. The activities are multidisciplinary and have involved both engineers (structural and industrial) and architects (urban planner and specialist in historical buildings). The goal was to obtain a comprehensive approach to old towns reconstruction. This activity is particularly important to minimize the earthquake consequences.Two peculiar aspects of the work are selected among other ones and presented within this paper. The first one is: how reliable are speedy in-situ surveys, in order to evaluate post-earthquake damages and building occupancy? Considering that both people safety and reconstruction funding depend on this judgment, it is important to check the procedure reliability. The second aspect is the analysis of an old urban center, viewed as a system of fragile components. System components are both material (e.g. a particular building) and immaterial (e.g. availability of the road system), and have been selected to maximize inhabitants safety, above all in terms of first aid to injured people and in terms of efficiency of strategic structures and infrastructures. These considerations are being slowly introduced in the Seismic Italian Code.
Structural Condition Evaluation of an In-Service Glued-Laminated Timber Bridge Based on the Dynamic and Static Testing
Authors: Wang Zhi Feng , Zhou Xian Yan , Zhang Da Hai
Published: July 2016

The structural use of wood has increased steadily in recent times, including a renewed interest in the use of timber as a bridge material. As the only environment-friendly and resource-saving building material, wood has been gradually uesd for short and medium span bridges in China. In 2014, The domestic largest single-span glued-laminated timber (glulam) deck arch bridge crossing a freeway was completed and put into operation in Zhangjiajie City, central China' Hunan province. In order to know the bearing capacity of superstructures and assess its working conditions, in-site static and dynamic testings has been carried out. Many measures including finite element simulation, field test and comparision between test results and calculated results have been employed to study responses of the bridge under static loads and dynamic loads as well. The researches indicate this glulam footbridge has performed well in service and appear to be cost effective when compared with the cost of installing traditional concrete and steel bridges.
Proposal of a Modal Pushover Based Incremental Analysis
Authors: Bergami Alessandro Vittorio , Xu Liu , Nuti Camillo
Published: July 2016

Existing reinforced concrete frame buildings designed for vertical load only could suffer severe damage during earthquakes. In recent years, many research activities have been paid to develop reliable and practical analysis procedure to identify the safety level of existing structures. The research discussed in this paper deals with proposal of an efficient incremental procedure to estimate seismic capacity of irregular structures performing few pushover analysis (one for every relevant modal shape) and applying a series of Modal Pushover Analysis (MPA). This approach, similar to the Incremental Dynamic Analysis (IDA), replaces the Nonlinear Response History Analyses (NL_RHA) by simple pushover analyses. In this work, this idea, named IMPA (Incremental Modal Pushover Analysis), is proposed for a 3D complex building and this application is described and discussed.
Structural Strengthening of the Portico of the Santa Maria Dei Servi Church in Bologna
Authors: Baraccani Simonetta , Palermo Michele , Gasparini Giada , Silvestri Stefano , Trombetti Tomaso , Dallavalle Gilberto
Published: July 2016

The porticoes, together with medieval masonry towers, are the architectural element which mainly characterizes the city of Bologna, northern Italy. These porticoes, which extend all inside the city centre for a total length of almost 40 kilometres, have a high artistic and cultural relevance at the point that they are candidates as “Unesco World Heritage Site”. One of portico of highest heritage value is that next to the church of Santa Maria dei Servi, which is suffering important structural pathologies requiring urgent strengthening interventions. The ones strictly necessary to preserve the stability have been already implemented. It is known that for historical constructions appropriate strategies of interventions are to be adopted with special attention in the aspects related to the compatibility, durability, integrity of the original configuration. The aim of this paper is to identify the main criticalities and priorities of interventions. Based on the identified criticalities and priorities possible strategies of interventions are finally identified. A possible cause of the actual bad state of conservation could be related to the continues vibrations induced by the traffic. For this reason, measurements noises have been recently conducted by the Italian National Institute of Geophysics and Volcanology (INGV) in order to quantify their influence of the stress levels of the columns of the portico.
Influence of Masonry Infills on the Shear Forces of RC Framed Structures
Authors: Perrone Daniele , Saponaro Vincenzo , Leone Marianovella , Aiello Maria Antonietta
Published: July 2016

The damages observed during the earthquakes occurred in the last decades have clearly shown as the influence of infill panels on the seismic behaviour of Reinforced Concrete (RC) buildings should be taken into account; the global stiffness and the strength of the RC frames are significantly modified by the infills. In the present study the influence of infills in terms of shear forces has been analyzed by means of linear static analysis; a parametric study has been carried out to evaluate the behavior of infilled frames varying both modelling approach and the mechanical properties of the masonry infills. In terms of modelling approach the single and multi-strut models have been adopted; the Young modulus of masonry infills have been varied in the common range proposed in literature. The results show that multi-strut approach is able to predict both global and local behavior. In addition, the importance of the mechanical properties of masonry infills in the evaluation of the elastic period and shear force in the columns is underlined.
Axial-Bending Interaction Diagrams of Reinforced Concrete Columns Exposed to Chloride Attack
Authors: Marano Giuseppe Carlo , Greco Rita
Published: July 2016

This paper focuses on reinforced concrete columns load carrying capacity degradation over time due to chloride induced steel pitting corrosion. The structural element is exposed to marine environment and the effects of corrosion are described by the time degradation of the axial-bending interaction diagram. Because chlorides ingress and consequent pitting corrosion propagation are both time-dependent mechanisms, the study adopts a time-variant predictive approach to evaluate residual strength of corroded reinforced concrete columns at different lifetimes. Corrosion initiation and propagation process is modelled by taking into account all the parameters, such as external environmental conditions, concrete mix proportion, concrete cover and so on, which influence the time evolution of the corrosion phenomenon and its effects on the residual strength of RC columns.
Research on Fresh Concrete Water-Cement Ratio Based on Resistivity Method
Authors: Ren Hai Bo , Yin Jian , Sang Zheng Hui , Gao Ting
Published: July 2016

Water-cement ratio is an important parameter of concrete quality. Rapid measurement of fresh concrete water-cement ratio can effectively monitor the on-site concrete quality management and play a great role in quality control. We study the variation of fresh concrete resistivity with the aid of electrodeless cement concrete resistivity meter, and discuss the impact of water-cement ratio under different varieties of cement, mineral admixture, chemical admixtures conditions on fresh concrete resistivity. We establish the relationships between fresh concrete resistivity and water-cement ratio based on the law of Portland cement initial hydration resistivity. The studies show that: fresh concrete resistivity is most vulnerable to the changes of water-cement ratio; there is a correlation between the law of fresh concrete resistivity and water-cement ratio; according to the fresh concrete resistivity variation, we can quickly identify water-cement ratio, cement and other parameters.
Steel to Concrete Bond Transferring in CFST Columns Connected to Beams through the Concrete
Authors: Somma Giuliana , Pieretto Alessandro , Dassie' Alberto
Published: July 2016

An important innovation in structural design in the last thirty years has been the use of steel-concrete composite columns, with particular diffusion of tubular profiles. These elements are known in the technical Literature as concrete filled steel tube (CFST) and the metal profiles that characterize the external jacket are usually circular, square or rectangular.A relevant issue that must be considered is the transfer of shear stresses by adhesion between steel and concrete in composite columns. The problem of adhesion, and thus its formulation, depends primarily on the type of technology used to connect beams to columns. In particular, two different models can be produced: the first case where the beams are connected only to the metal external jacket of the pillar (i.e. steel beams connected with bolted flanges to the column), and the second where beams and columns are connected also in the concrete matrix (i.e. the case of beams in steel-concrete technology, or traditional reinforced concrete beams).International Standards, regarding the problem of adhesion in jacketed columns, only referee to the first connection type, giving a constant value for adhesion coefficient along the transferring length, with no dependence to the size of the section, and indicate transferring lengths independently from the type of beam-to-column connection and the shape of the section. In the Paper are hence proposed expressions that quantify the fundamental values that govern the action transfer mechanism by adhesion in CFST, such as the transfer length, the perimeter of the active transfer and the shear stress distribution, as a function of the slenderness ratio and of the type of connection adopted. All this has been carried in order to produce a model for the estimation of bond stresses for the second of the two construction system mentioned above.
Use of Electric Arc Furnace Slag for High Strength Concrete Production
Authors: Faleschini Flora , Zanini Mariano Angelo , Brunelli Katya , Pellegrino Carlo
Published: July 2016

In this paper the use of Electric Arc Furnace slag (EAF slag) for the production of High-Performances Concrete (HPC) is explored, as a fully replacement of the natural gravel. Several mixtures were produced, varying the water/cement ratio, the cement and the admixture content, with the aim of reaching a strength class between C50/60 and C60/75, and an S4 consistency class, as defined in EN 206-1. Mechanical properties of EAF concretes were compared with reference conglomerates; a complementary microstructural analysis was performed, with SEM observation after concrete specimens' failure. Results indicate that the use of EAF slag in concrete allows reaching higher compressive strength than with coarse natural aggregates. Lastly, the environmental benefits obtained through the use of recycled aggregates are shown, by means of the application of a Life Cycle Assessment (LCA) tool properly developed for this scope.
Rezensionen
Authors: Jolissaint Paul
Published: July 2016

Rezension zu:
A.E. Kossovsky:
Benford’s law. Theory, the general law of relative quantities, and forensic detection applications
. xxi + 649 pages, GBP43.00. World Scientific Publishing Co. Pte. Ltd. Singapore, 2015; ISBN 978-981-4651-20-2 (soft cover).
The strong profinite genus of a finitely presented group can be infinite
Authors: Bridson Martin R.
Published: July 2016

We construct the first examples of finitely-presented, residually-finite groups

\Gamma

that contain an infinite sequence of non-isomorphic finitely-presented subgroups

P_n \hookrightarrow \Gamma

such that the inclusion maps induce isomorphisms of profinite completions

\widehat{P}_n \cong \widehat {\Gamma}

.
Pseudo-holomorphic functions at the critical exponent
Authors: Baratchart Laurent , Borichev Alexander , Chaabi Slah
Published: July 2016

We study Hardy classes on the disk associated to the equation

\bar \partial w= \alpha \bar w

for

\alpha \in L^r

with

2 \leq r < \infty

. The paper seems to be the first to deal with the case

r=2

. We prove an analog of the M. Riesz theorem and a topological converse to the Bers similarity principle. Using the connection between pseudo-holomorphic functions and conjugate Beltrami equations, we deduce well-posedness on smooth domains of the Dirichlet problem with weighted

L^p

boundary data for 2D isotropic conductivity equations whose coefficients have logarithm in

W^{1,2}

. In particular these are not strictly elliptic. Our results depend on a new multiplier theorem for

W^{1,2}_0

-functions.
Bounds on the Bondi energy by a flux of curvature
Authors: Alexakis Spyros , Shao Arick
Published: July 2016

We consider smooth null cones in a vacuum spacetime that extend to future null infinity. For such cones that are perturbations of shear-free outgoing null cones in Schwarzschild spacetimes, we prove bounds for the Bondi energy, momentum, and rate of energy loss. The bounds depend on the closeness between the given cone and a corresponding cone in a Schwarzschild spacetime, measured purely in terms of the differences between certain weighted

L^2

-norms of the spacetime curvature on the cones, and of the geometries of the spheres from which they emanate. This paper relies on the results in [1], which uniformly control the geometry of the given null cone up to infinity, as well as those of [18], which establish machinery for dealing with low regularities. A key step in this paper is the construction of a family of asymptotically round cuts of our cone, relative to which the Bondi energy is measured.
Effects of aerobic exercise of different intensities in the liver of metabolic syndrome animals
Authors: Sousa L. , Saucedo S. , Veloso A. , Machi J. , Wichi R. , Ornelas E. , Maifrino L.
Published: July 2016

Introduction: Metabolic syndrome (MS) corresponds to a sum of alteration in which, glucose intolerance is characterized as one of the most important. Among these are included: insulin resistance, type 2 diabetes mellitus, hypertension, obesity, dyslipidemia, endothelial dysfunction and others Nonalcoholic steatohepatitis (NASH) is also currently cited as a risk factor for MS Studies have demonstrated a strong correlation between physical inactivity and MS. The aim of this paper was to evaluate the effects of aerobic exercise training of different intensities on the liver of metabolic syndrome rats. Methods: 20 male Wistar rats were used and divided into four groups (n=5): control (C) sedentary MS (MS), walking MS (WMS) and running MS (RMS). Fructose-drinking rats received D-fructose (100 g/l). MS Training rats were assigned to a treadmill training protocol at low and moderate intensity during 1 h/day, 5 days/week for 8 weeks. At the end of the experiment, the livers were collected and submitted to a histological technique (HE). The images were captured and morphometric and stereological analysis of the hepatic tissue were performed. Results: It was verified that MS promoted a hypertrophy of the hepatocytes, a significant increase in the density volume of the hepatocytes, of the Kupffer cells, and hepatic sinusoids, and that, in both intensities (Running and Walking) the exercise training has mitigated the alterations. Conclusions: The data suggest, as nonpharmacological treatment, the walking (low intensity) is the most eficient, able to reverse the alterations caused by metabolic syndrome, the results being approximate to those of control group.
Musculoskeletal analysis of masticatory system arising from malocclusion: literature review
Authors: Casarin C. , Palma R. , Arsa G. , Andrade E. , Leite G. , Bocalini D. , Serra A. , Suzuki F. , Caria P.
Published: July 2016

Introduction: The malocclusion can be defined as any change in the natural position of contact between the teeth and the arcades format that affects the morphofunctional architecture of the masticatory system of individuals affected by such condition. The aim of this study was to review the literature and to investigate the morphofunctional changes of the mandible and masticatory muscles as result of malocclusion. Material and Methods: This study consisted of a systematic review and the search for the theoretical composition was performed in the Lilacs, PubMed and Scielo database using as descriptors the words Malocclusion, Mandible, Masticatory Muscles and as filters the words Abstract Available, English Language, Humans, Rats. Results: This research allowed the authors to assert that the occlusal alterations are capable of causing morphological and functional modifications in the mandible and masticatory muscles. Conclusion: Given these aspects, it was possible to highlight the malocclusion as an aggravating factor at quality of life.
Ice nucleating particles in the Saharan Air Layer
Authors: Boose Yvonne , Sierau Berko , García M. Isabel , Rodríguez Sergio , Alastuey Andrés , Linke Claudia , Schnaiter Martin , Kupiszewski Piotr , Kanji Zamin A. , Lohmann Ulrike
Published: July 2016

Abstract. This study aims at quantifying the ice nucleation properties of desert dust in the Saharan Air Layer (SAL), the warm, dry and dust-laden layer that expands from North Africa to the Americas. By measuring close to the dust's emission source, before aging processes during the transatlantic advection potentially modify the dust properties, the study fills a gap between in situ measurements of dust ice nucleating particles (INPs) far away from the Sahara and laboratory studies of ground-collected soil. Two months of online INP concentration measurements are presented, which were part of the two CALIMA campaigns at the Izaña observatory in Tenerife, Spain (2373 m a.s.l.), in the summers of 2013 and 2014. INP concentrations were measured in the deposition and condensation mode at temperatures between 233 and 253 K with the Portable Ice Nucleation Chamber (PINC). Additional aerosol information such as bulk chemical composition, concentration of fluorescent biological particles as well as the particle size distribution was used to investigate observed variations in the INP concentration. The concentration of INPs was found to range between 0.2 std L−1 in the deposition mode and up to 2500 std L−1 in the condensation mode at 240 K. It correlates well with the abundance of aluminum, iron, magnesium and manganese (R: 0.43–0.67) and less with that of calcium, sodium or carbonate. These observations are consistent with earlier results from laboratory studies which showed a higher ice nucleation efficiency of certain feldspar and clay minerals compared to other types of mineral dust. We find that an increase of ammonium sulfate, linked to anthropogenic emissions in upwind distant anthropogenic sources, mixed with the desert dust has a small positive effect on the condensation mode INP per dust mass ratio but no effect on the deposition mode INP. Furthermore, the relative abundance of biological particles was found to be significantly higher in INPs compared to the ambient aerosol. Overall, this suggests that atmospheric aging processes in the SAL can lead to an increase in ice nucleation ability of mineral dust from the Sahara. INP concentrations predicted with two common parameterization schemes, which were derived mostly from atmospheric measurements far away from the Sahara but influenced by Asian and Saharan dust, were found to be higher based on the aerosol load than we observed in the SAL, further suggesting aging effects of INPs in the SAL.
Can we detect regional methane anomalies? A comparison between three observing systems
Authors: Cressot Cindy , Pison Isabelle , Rayner Peter J. , Bousquet Philippe , Fortems-Cheiney Audrey , Chevallier Frédéric
Published: July 2016

Abstract. A Bayesian inversion system is used to evaluate the capability of the current global surface network and of the space-borne GOSAT/TANSO-FTS and IASI instruments to quantify surface flux anomalies of methane at various spatial (global, semi-hemispheric and regional) and time (seasonal, yearly, 3-yearly) scales. The evaluation is based on a signal-to-noise ratio analysis, the signal being the methane fluxes inferred from the surface-based inversion from 2000 to 2011 and the noise (i.e., precision) of each of the three observing systems being computed from the Bayesian equation. At the global and semi-hemispheric scales, all observing systems detect flux anomalies at most of the tested timescales. At the regional scale, some seasonal flux anomalies are detected by the three observing systems, but year-to-year anomalies and longer-term trends are only poorly detected. Moreover, reliably detected regions depend on the reference surface-based inversion used as the signal. Indeed, tropical flux inter-annual variability, for instance, can be attributed mostly to Africa in the reference inversion or spread between tropical regions in Africa and America. Our results show that inter-annual analyses of methane emissions inferred by atmospheric inversions should always include an uncertainty assessment and that the attribution of current trends in atmospheric methane to particular regions' needs increased effort, for instance, gathering more observations (in the future) and improving transport models. At all scales, GOSAT generally shows the best performance of the three observing systems.
Daytime formation of nitrous acid at a coastal remote site in
Cyprus indicating a common ground source of atmospheric
HONO and NO
Authors: Meusel Hannah , Kuhn Uwe , Reiffs Andreas , Mallik Chinmay , Harder Hartwig , Martinez Monica , Schuladen Jan , Bohn Birger , Parchatka Uwe , Crowley John N. , Fischer Horst , Hoffmann Thorsten , Janssen Ruud , Hartogensis Oscar , Pikridas M.Michael , Vrekoussis Mihalis , Bourtsoukidis Efstratios , Weber Bettina , Lelieveld Jos , Williams Jonathan , Pöschl Ulrich , Cheng Yafang , Su Hang
Published: July 2016

Abstract. Characterization of daytime sources of nitrous acid (HONO) is crucial to understand atmospheric oxidation and radical cycling in the planetary boundary layer. HONO and numerous other atmospheric trace constituents were measured on the Mediterranean island of Cyprus during the CYPHEX campaign (CYPHEX = CYprus PHotochemical EXperiment) in summer 2014. Average volume mixing ratios of HONO were 35 pptv (±25 pptv) with a HONO/NOx ratio of 0.33, which was considerably higher than reported for most other rural and urban regions. Diel profiles of HONO showed peak values in the late morning (60±28 pptv around 09:00 local time), and persistently high mixing ratios during daytime (45±18 pptv) indicating that the photolytic loss of HONO is compensated by a strong daytime source. Budget analyses revealed unidentified sources producing up to 3.4 × 106 molecules cm−3 s−1 of HONO and up to 2.0 × 107 molecules cm−3 s−1 NO. Under humid conditions (RH >70 %), the source strengths of HONO and NO exhibited a close linear correlation (R2 = 0.78), suggesting a common source that may be attributable to emissions from microbial communities on soil surfaces.
Large-Scale Vertical Velocity, Diabatic Heating and Drying Profiles Associated with Seasonal and Diurnal Variations of Convective Systems Observed in the GoAmazon2014/5 Experiment
Authors: Tang Shuaiqi , Xie Shaocheng , Zhang Yunyan , Zhang Minghua , Schumacher Courtney , Upton Hannah , Jensen Michael P. , Johnson Karen L. , Wang Meng , Ahlgrimm Maike , Feng Zhe , Minnis Patrick , Thieman Mandana
Published: July 2016

Abstract. This study describes the characteristics of large-scale vertical velocity, apparent heating source (Q1) and apparent moisture sink (Q2) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) of the Green Ocean Amazon (GoAmazon2014/5) experiment, which was conducted near Manaus, Brazil in 2014 and 2015. The derived large-scale fields have large diurnal variations according to convective activity in the GoAmazon region and the morning profiles show distinct differences between the dry and wet seasons. In the wet season, propagating convective systems originating far from the GoAmazon region are often seen in the early morning, while in the dry season, they are rarely observed. Afternoon convective systems due to solar heating are frequently seen in both seasons. Accordingly, in the morning, there is strong upward motion and associated heating and drying throughout the entire troposphere in the wet season, which is limited to lower levels in the dry season. In the afternoon, both seasons exhibit weak heating and strong moistening in the boundary layer related to the vertical convergence of eddy fluxes. A set of case studies of three typical types of convective systems occurring in Amazonia – i.e., locally-occurring systems, coastal-occurring systems and basin-occurring systems – is also conducted to investigate the variability of the large-scale environment with different types of convective systems.
Ideas and Perspectives: Climate-Relevant Marine Biologically-Driven Mechanisms in Earth System Models
Authors: Hense Inga , Stemmler Irene , Sonntag Sebastian
Published: July 2016

Abstract. Marine biota drives a number of climate-relevant mechanisms not all of which are included in current Earth system models (ESMs). We identify three classes of mechanisms and distinguish (1) those related to matter cycling via "biogeochemical pumps", (2) those affecting the atmospheric composition via the "biological gas and particle shuttles" and (3) those changing the thermal, optical and mechanical properties of the ocean via the "biogeophysical mechanisms". We argue that to adequately resolve these mechanisms, ESMs need to account for five functional groups, including bulk phyto- and zooplankton, calcifiers as well as coastal gas and surface mat producers. Thereby links to other Earth system components are ensured and a larger number of relevant feedbacks are enabled to take place.
Observing and modelling phytoplankton community structure in the
North Sea: can ERSEM-type models simulate biodiversity?
Authors: Ford David A. , van der Molen Johan , Hyder Kieran , Bacon John , Barciela Rosa , Creach Veronique , McEwan Robert , Ruardij Piet , Forster Rodney
Published: July 2016

Abstract. Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models have therefore yet to be properly validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical-biogeochemical ocean models, the biogeochemical components of which are different variants of the widely-used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. A comparison of the formulations and parameterisations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed biodiversity. These findings will help inform future model development, which should be coupled with detailed validation studies, in order to help facilitate the wider application of marine biogeochemical modelling to user and policy needs.
Reconstruction of spatially detailed global map of NH4+ and NO3− application in synthetic nitrogen fertilizer
Authors: Nishina Kazuya , Ito Akihiko , Hanasaki Naota , Hayashi Seiji
Published: July 2016

Abstract. This paper provides a method for constructing a new historical global nitrogen fertilizer application map (0.5° × 0.5° resolution) for the period 1961–2010 based on country-specific information from Food and Agriculture Organization statistics (FAOSTAT) and various global datasets. This new map incorporates the fraction of NH4+ (and NO3−) in N fertilizer inputs by utilizing fertilizer species information in FAOSTAT, in which species can be categorized as NH4+ and/or NO3−-forming N fertilizers. During data processing, we applied a statistical data imputation method for the missing data (19 % of national N fertilizer consumption) in FAOSTAT. The multiple imputation method enabled us to fill gaps in the time-series data using plausible values using covariates information (year, population, GDP, and crop area). After the imputation, we downscaled the national consumption data to a gridded cropland map. Also, we applied the multiple imputation method to the available chemical fertilizer species consumption, allowing for the estimation of the NH4+/NO3− ratio in national fertilizer consumption. In this study, the synthetic N fertilizer inputs in 2000 showed a general consistency with the existing N fertilizer map (Potter et al., 2010) in relation to the ranges of N fertilizer inputs. Globally, the estimated N fertilizer inputs based on the sum of filled data increased from 15 Tg-N to 110 Tg-N during 1961–2010. On the other hand, the global NO3− input started to decline after the late 1980s and the fraction of NO3− in global N fertilizer decreased consistently from 35 % to 13 % over a 50-year period. NH4+ based fertilizers are dominant in most countries; however, the NH4+/NO3− ratio in N fertilizer inputs shows clear differences temporally and geographically. This new map can be utilized as an input data to global model studies and bring new insights for the assessment of historical terrestrial N cycling changes. Datasets available at doi:10.1594/PANGAEA.861203.
Optical laboratory facilities at the Finnish Meteorological Institute – Arctic Research Centre
Authors: Lakkala Kaisa , Suokanerva Hanne , Karhu Juha Matti , Aarva Antti , Poikonen Antti , Karppinen Tomi , Ahponen Markku , Hannula Henna-Reetta , Kontu Anna , Kyrö Esko
Published: July 2016

Abstract. This paper describes the laboratory facilities at the Finnish Meteorological Institute – Arctic Research Centre (FMI-ARC, http://fmiarc.fmi.fi). They comprise an optical laboratory, a facility for biological studies, and an office. A dark room has been built, in which an optical table and a fixed lamp test system are set up, and the electronics allow high-precision adjustment of the current. The Brewer spectroradiometer, NILU-UV multifilter radiometer, and Analytical Spectral Devices (ASD) spectroradiometer of the FMI-ARC are regularly calibrated or checked for stability in the laboratory. The facilities are ideal for responding to the needs of international multidisciplinary research, giving the possibility to calibrate and characterize the research instruments as well as handle and store samples.
Hydrological modeling in glacierized catchments of Central Asia: status and challenges
Authors: Chen Yaning , Li Weihong , Fang Gonghuan , Li Zhi
Published: July 2016

Abstract. Glaciers are one of the most important water supplies of glacierized catchments in Central Asia. Therefore, the effects of climate change on glaciers, snow cover and permafrost will have increasingly significant consequences for runoff. Hydrological modeling has become an indispensable research approach to water resources management in large glacierized river basins, but there is a lack of focus in the modeling of glacial discharge. This paper reviews the status of hydrological modeling in glacierized catchments of Central Asia, discussing the limitations of the available models and extrapolating these to future challenges and directions. After reviewing recent efforts, we conclude that the main sources of uncertainty in assessing the regional hydrological impacts of climate change are the unreliable and incomplete datasets and the lack of understanding of the hydrological regimes of glacierized catchments of Central Asia. Runoff trends indicate a complex response of catchments to changes in climate. For future variation of water resources, it is essential to quantify the responses of hydrologic processes to both climate change and shrinking glaciers in glacierized catchments, and scientific focus should be on reducing these uncertainties.
Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery (ASR) in a coastal subsurface
Authors: Zuurbier Koen Gerardus , Stuyfzand Pieter Jan
Published: July 2016

Abstract. Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated, intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and SEAWAT transport modelling. The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR-bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the MPPW-ASR system was observed. This "leakage" may lead to a lower recovery efficiency than based on current ASR performance estimations.
Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model
Authors: Tangdamrongsub N. , Steele-Dunne S. C. , Gunter B. C. , Ditmar P. G. , Sutanudjaja E. H. , Sun Y. , Xia T. , Wang Z.
Published: July 2016

Abstract. An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of Terrestrial Water Storage (TWS) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an Ensemble Kalman Filter (EnKF) approach. The region considered was the Hexi Corridor of Northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. In this study, EnKF 3D scheme, which accounts for the GRACE spatially-correlated errors, was used. The correlated errors were propagated from the full error variance-covariance matrices provided as a part of the GRACE data product. The impact of the GRACE Data Assimilation (DA) scheme was evaluated in terms of the TWS, as well as individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWS but also for the groundwater component, which had annual amplitude, phase, and long-term trend estimates closer to the GRACE observations. This study also assessed the benefits of taking into account correlations of errors in GRACE-based estimates. The assessment was carried out by comparing the EnKF results, with and without taking into account error correlations, with the in situ groundwater data from 5 well sites and the in situ streamflow data from two river gauges. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. No significant benefits of GRACE DA were observed in terms of streamflow estimates, which reflect a limited spatial and temporal resolution of GRACE observations. Results from the 9-year long GRACE DA study were used to assess the status of water resources over the Hexi Corridor. Areally-averaged values revealed that TWS, soil moisture, and groundwater storages over the region decreased with an average rate of approximately 0.2, 0.1, and 0.1 cm/yr in terms of equivalent water heights, respectively. A substantial decline in TWS (approximately −0.4 cm/yr) was seen over the Shiyang River Basin in particular, and the reduction mostly occurred in the groundwater layer. An investigation of the relationship between water resources and agriculture suggested that groundwater consumption required to maintain the growing period in this specific basin was likely the cause of the groundwater depletion.
Retinal Nerve Fiber and Optic Disc Morphology Using Spectral-Domain Optical Coherence Tomography in Scleroderma Patients
Authors: Sahin-Atik Sevinc , Koc Feray , Akin-Sari Sirin , Ozmen Mustafa
Published: July 2016

Purpose

To evaluate the optic nerve head parameters and peripapillary retinal nerve fiber layer using spectral-domain optical coherence tomography (SD-OCT) in a systemic sclerosis (SSc) cohort and age-matched controls to determine whether SSc patients have an increased risk of normal-tension glaucoma (NTG).

Methods

We examined 30 patients (3 male, 27 female) with SSc and 28 age- and sex-matched controls. Retinal nerve fiber and optic disc morphology were evaluated using Cirrus SD-OCT.

Results

Optic disc morphology measurements including disc area, rim area, average and vertical cup/disc (C/D) ratio, and cup volume were not significantly different between the study groups. The average and 4-quadrant retinal nerve fiber layer (RNFL) measurements of the C/D >0.3 subgroups were not significantly different in the patients and controls. These values were also similar for the C/D >0.5 subgroups except that the average inferior quadrant RNFL thickness of the right eyes in the patient subgroup was significantly thinner than in the control subgroup (p<0.05).

Conclusions

Our SSc cohort had relatively shorter disease duration but increased prevalence of early glaucomatous damage signs. Our findings indicate that SSc is a risk factor for developing normal-tension glaucoma. Further studies combined with visual field evaluation are necessary to identify the long-term glaucomatous effects of SSc.
Hypotonic Maculopathy Secondary to Scleral Defect in Atypical Retinochoroidal Coloboma
Authors: Fiore Tito , Pellegrino Adriana , Lupidi Marco , Cerquaglia Alessio , Giansanti Fabrizio , Cagini Carlo
Published: July 2016

Purpose

To describe a patient with unilateral hypotonic maculopathy and optic disc edema after spontaneous bulbar perforation of a full-thickness scleral defect.

Methods

An 11-year-old girl underwent scleral buckling surgery. Preoperative and postoperative evaluation included optical coherence tomography and high-resolution 3T magnetic resonance imaging.

Results

The scleral defect was covered with Tenon capsule sheaths and a meridional silicone buckle. One year postoperatively, visual acuity and macular and optic disc morphology were completely restored.

Conclusions

Ocular hypotony related to a defect of the sclera forming the roof of a retinochoroidal coloboma is a rare event. Hypotony was a consequence of a defect at the level of an atypical retinochoroidal coloboma where the scleral wall was found to be absent.