bluuebunny/crossref_metadata_2025 huggingface dataset:
A Heterogeneous Cross-Domain Authentication Model Based on Access Tickets in Virtual Cable Television Network
Authors: Wang Yu , Wang Yong Li
Published: March 2015

The virtual cable television network is a cable television system with virtual assets, users in the network may have different authentication mechanisms. In order to meet corporate users across heterogeneous virtual, trusted domain request service is required. This paper proposes a bill based on the access authorization authentication scheme across heterogeneous domains. The scheme is based on VCA certification model, the Kerberos AS and the PKI domain as the domain where the CA Enterprise Domain external authentication node, generate its extracellular domain users access, the domain resources authorization bill and the session key, and then realize PKI and Kerberos cross-domain authentication ,domain user and session key agreement. Article on the safety and efficiency of the program are analyzed. Analysis shows that this scheme can resist various attacks, with high security, and higher than the efficiency of alternative solutions for virtual cable television network, efficient resource sharing of cross-domain security provides an effective solution.
Multi-Tag RFID Identification and Anti-Collision Algorithm
Authors: Wang Jing , Tian Hong Xia , Cui Xue Wei , Wang Ying Jie
Published: March 2015

This paper presents a collision algorithm based on frame slots RFID tag identification and prevention, algorithms on performance is more stable, less total cost of the number of time slots. For the anti-collision algorithm for the simulation, the average number of searches were simulated contrast of the number of tags and the number of slots and different algorithms collision situations relations, research results show that this type of algorithm is effective in reducing the identification number of the reader's request to reduce the energy consumed by the reader, particularly suitable for applications in handheld reader today.
Research on Mass Determination of International Comparison CCM.M-K4 of 1 kg Mass Weights
Authors: Hu Man Hong , Wang Jian , Zhang Yue , Cai Chang Qing , Zhong Rui Lin , Yao Hong , Ding Jing An
Published: March 2015

CCM.M-K4 is a key international comparison organized by the Bureau International des Poids et Mesures (BIPM) to verify the measurement ability of 1kg stainless weights. This paper reports the process analysis of mass determination of CCM.M-K4 during the measurement in NIM, China. The gravity correction and air bouncy correction are discussed, and the measuring uncertainties of measurement process are evaluated. Mass difference between the test standards is 0.0015 mg, and average mass of both test standards is 0.013 mg. The standard uncertainty of test weights is 0.013 mg.
The Tween-60-Assisted Preparation of Pd/C Catalyst and its Application in Suzuki Coupling Reactions
Authors: Bai Xue Feng , Wang Hai Yang
Published: March 2015

The Pd/C catalyst with high dispersion was prepared by the activated carbon loading palladium nanoparticles (Pd-NPs) obtained in the protection of Tween-60. The above-prepared Pd/C catalyst was characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), chemical adsorption instrument. The influences of the size, dispersion, crystal type and electronic state of the Pd/C catalyst on catalytic activity were investigated. The results of Suzuki coupling reaction over the above-prepared Pd/C demonstrated that the reaction yield of aryl bromide under the conditions of 60°C for 1 h and para-chloronitrobenzene under the conditions of 80°C for 12 h reach 99% and 73% respectively.
Application of Atomic Force Microscopy Characterization Technology in MgAl-CO32--LDH Exfoliation Behavior
Authors: Zhang Jie , Xie Xiang Li , Li Cun Jun , Wang Hai , Wang Lin Jiang
Published: March 2015

MgAl-CO32--LDH was exfoliated via two-step ultrasonic treatment in formamide. Atomic force microscopy (AFM) was employed to characterize the thickness variation of MgAl-CO32--LDH during exfoliation. MgAl-CO32--LDH was dispersed in formamide with continuous ultrasonic treatment for 4 h, getting a non-transparent turbid liquid. The non-transparent turbid liquid was laid aside one day and separated into two phases, the upper semi-translucent colloidal suspension containing partial exfoliated MgAl-CO32--LDH was dispersed in formamide with continuous ultrasonic treatment again. The AFM results reveal that the thickness of pristine MgAl-CO32--LDH is 250 nm while the MgAl-CO32--LDH nanosheet obtained from the first-step ultrasonic treatment is 90 nm with obvious transverse sliding. The thickness of MgAl-CO32--LDH nanosheet obtained after the second-step ultrasonic treatment is about 7 nm, which is almost in agreement with the theoretical thickness of 10 monolayers of MgAl-CO32--LDH (0.76 nm).
Properties of LaNi4.3Al0.7 Applied in Separating Hydrogen from Coke Oven Gas
Authors: Chen Xu Yang , Ma Xiao Xin , Zhou Lu , Yang Fu Sheng , Zhang Zao Xiao
Published: March 2015

Nowadays hydrogen as an important source of energy is still produced from fossil fuel processing largely, hence the separation of hydrogen from the gas mixture with high recovery ratio and purity arises as an important issue. In this paper we proposed a hydrogen recovery/production process from half-coke oven gas, and the material LaNi4.3Al0.7 was considered for use due to its low plateau pressure and good resistance to impurities. We use a Sieverts type volumetric apparatus to investigate the material properties,including P-C-T properties and hydriding/ dehydriding kinetics under different conditions. Based on the results obtained, the feasibility of using the material for gas separation purpose was discussed.Keywords: Gas separation; metal hydride; reaction kinetics; P-C-T properties; Sieverts method
Jointing of Zirconia Ceramic and Titanium Alloy
Authors: Hu Xiang Feng
Published: March 2015

Zirconia ceramic and titanium alloy were jointed by using an AgCuTi amorphous alloy as a solder. The microstructure and the properties of the joint are investigated. The results show that the microstructure and mechanical properties of the brazing seam are influenced by the brazing temperature, the heat time and the cooling rate. The shear strength of the joint decreases with increasing of the brazing temperature, the heat time and the cooling rate increase. The maximum shear strength of the joints reaches 178 Mpa. The optimal technical parameters are the brazing temperature of 1123 K, the heat time of 10 min and the cooling rate of 5 K/min.
A New High Precise Powder Feeder for Fabricating Functionally Gradient Metal Component
Authors: Zou Hai Ping , Chen Ming Wei , Li Yao
Published: March 2015

In this paper, a new high precise powder feeder designed for fabricating functionally gradient metal component was presented. The mechanism, control principle and computer control program of the powder feeder were introduced and the powder feeding precise test experiments were carried out with Ni-based alloy powders, Fe-based alloy powders and ceramic powders in the particle average diameter of 15-350 Microns. Experimental results showed that the powders mixtures obtained from the high precise powder feeder are continuous and stable. The precision of delivering powders mixture can be weighed within 2% error scope comparing to the desired mixture quality and the flexible proportion of different powders mixture can be easy changed in the computer control program by synchronously controlling the powder feeder motor’s rotation speed.
The Causes Analysis for the Surface Wrinkle Defects of Cold-Rolled Strip and the Control Measures
Authors: Li Guang Lin , Chen Xi Liang , Hu Zhi Yuan , Wang Fu Xing , Shang Guang Peng , Shi Ai Chen
Published: March 2015

Based on the surface wrinkle defects of cold-rolled strip, the causes and the mechanism were analyzed, the reasons for edge thickening of cold-rolled strip were elaborated, and put forward the corresponding control measures, which achieved good results.
The Analysis of Process Information Characteristics for Wire-Sheet Spot Welding
Authors: Li Hai Bo , Cao Biao , Cui Xiao Yu
Published: March 2015

During the resistance spot welding quality control process, the traditional quality control methods can’t compensate all the affecting factors effectively. By welding 316LVM stainless steel wire to the surface of sheet of the same material, three kinds of process parameters, including electrode voltage, dynamic resistance and electrode displacement which affected by many affecting factors during the spot welding process were measured and analyzed. The results show that, by comparing with the process parameters during the normal situation, the dynamic change of the these process parameters during different stage appears distinguishable characteristics, these characteristics would supply a research basis for recognizing whether the affecting factors exist.
Leaching Experiment Study on Silver Ore in Yunnan Province
Authors: Liu Dan , Li Jin Lin , Wen Shu Ming , Wang Yi Jie
Published: March 2015

A leaching experiment was launched on silver ore whose silver content is 101.6g/t in Yunnan province, China. Technological mineralogy research of the ore indicates that the content of carbon which is bad for leaching is 2.23%. Leachable silver minerals mainly are oxidized silver, elemental silver and silver sulfide. And the theory leaching ratio of the silver ore is 67.43%. When the content of-74um is 75%; dosage of sodium cyanide is 4.5kg/t; dosage of lime is 0.5kg/t; velocity of agitation is 400r/min; leaching time is 24h, a best indicator which leaching ratio is 70.47% can be obtained. Meanwhile, silver in lixivium is 20.42mg/L.
Research on Exploration of Mineral Processing for a Iron Ore
Authors: Xie Xian , Yang Zi  Xuan , Tong Xiong , Li Ji Yong
Published: March 2015

Iron ore minerals are mainly silicate-type iron minerals in raw ore, and its distribution rate was 51.93%; followed by magnetic iron, and its distribution rate was 36.81%; content and distribution rate of other minerals was very low; element grade of iron, phosphorus, sulfur, silica were 11.90%, 0.043%, 0.013% and 45.23%, the main gangue were silica and calcium oxide, recyclable iron minerals mainly is magnetic iron mineral. Due to the grade of iron of raw ore and the amounts of optional magnetite was relatively little, in order to investigate the optional of low-grade ore, weak magnetic separation test and weak magnetic separation tailings-strong magnetic separation test were put into effect.
Frame Strength and Stiffness Analysis Based on ANSYS
Authors: Shen Jiang Feng , He Yu Jing , Yu Yong Chang
Published: March 2015

A Case Study in spraying trailers, the frame of the structural characteristics were analyzed, using ANSYS workbench finite element analysis software for the frame were static stress analysis. First, create a physical model of the frame in Solidworks software. Then import ANSYS workbench on the frame payload processing constraints and suffered, were analyzed by calculating the frame strength and stiffness, get the frame stress cloud and find the weak links in the frame. To improve frame structure provides a theoretical basis.
A RESTful API for Access to Phylogenetic Tools via the CIPRES Science Gateway
Authors: Miller Mark A. , Schwartz Terri , Pickett Brett E. , He Sherry , Klem Edward B. , Scheuermann Richard H. , Passarotti Maria , Kaufman Seth , O'Leary Maureen A.
Published: March 2015

The CIPRES Science Gateway is a community web application that provides public access to a set of parallel tree inference and multiple sequence alignment codes run on large computational resources. These resources are made available at no charge to users by the NSF Extreme Science and Engineering Discovery Environment (XSEDE) project. Here we describe the CIPRES RESTful application programmer interface (CRA), a web service that provides programmatic access to all resources and services currently offered by the CIPRES Science Gateway. Software developers can use the CRA to extend their web or desktop applications to include the ability to run MrBayes, BEAST, RAxML, MAFFT, and other computationally intensive algorithms on XSEDE. The CRA also makes it possible for individuals with modest scripting skills to access the same tools from the command line using curl, or through any scripting language. This report describes the CRA and its use in three web applications (Influenza Research Database – www.fludb.org , Virus Pathogen Resource – www.viprbrc.org , and MorphoBank – www.morphobank.org ). The CRA is freely accessible to registered users at https://cipresrest.sdsc.edu/cipresrest/v1 ; supporting documentation and registration tools are available at https://www.phylo.org/restusers .
Trends of ozone total columns and vertical distribution from FTIR observations at eight NDACC stations around the globe
Authors: Vigouroux C. , Blumenstock T. , Coffey M. , Errera Q. , García O. , Jones N. B. , Hannigan J. W. , Hase F. , Liley B. , Mahieu E. , Mellqvist J. , Notholt J. , Palm M. , Persson G. , Schneider M. , Servais C. , Smale D. , Thölix L. , De Mazière M.
Published: March 2015

Abstract. Ground-based Fourier transform infrared (FTIR) measurements of solar absorption spectra can provide ozone total columns with a precision of 2% but also independent partial column amounts in about four vertical layers, one in the troposphere and three in the stratosphere up to about 45km, with a precision of 5–6%. We use eight of the Network for the Detection of Atmospheric Composition Change (NDACC) stations having a long-term time series of FTIR ozone measurements to study the total and vertical ozone trends and variability, namely, Ny-Ålesund (79° N), Thule (77° N), Kiruna (68° N), Harestua (60° N), Jungfraujoch (47° N), Izaña (28° N), Wollongong (34° S) and Lauder (45° S). The length of the FTIR time series varies by station but is typically from about 1995 to present. We applied to the monthly means of the ozone total and four partial columns a stepwise multiple regression model including the following proxies: solar cycle, quasi-biennial oscillation (QBO), El Niño–Southern Oscillation (ENSO), Arctic and Antarctic Oscillation (AO/AAO), tropopause pressure (TP), equivalent latitude (EL), Eliassen–Palm flux (EPF), and volume of polar stratospheric clouds (VPSC). At the Arctic stations, the trends are found mostly negative in the troposphere and lower stratosphere, very mixed in the middle stratosphere, positive in the upper stratosphere due to a large increase in the 1995–2003 period, and non-significant when considering the total columns. The trends for mid-latitude and subtropical stations are all non-significant, except at Lauder in the troposphere and upper stratosphere and at Wollongong for the total columns and the lower and middle stratospheric columns where they are found positive. At Jungfraujoch, the upper stratospheric trend is close to significance (+0.9 ± 1.0% decade−1). Therefore, some signs of the onset of ozone mid-latitude recovery are observed only in the Southern Hemisphere, while a few more years seem to be needed to observe it at the northern mid-latitude station.
Implementation of a GPS-RO data processing system for the KIAPS-LETKF data assimilation system
Authors: Kwon H. , Kang J.-S. , Jo Y. , Kang J. H.
Published: March 2015

Abstract. The Korea Institute of Atmospheric Prediction Systems (KIAPS) has been developing a new global numerical weather prediction model and an advanced data assimilation system. As part of the KIAPS package for observation processing (KPOP) system for data assimilation, preprocessing, and quality control modules for bending-angle measurements of global positioning system radio occultation (GPS-RO) data have been implemented and examined. The GPS-RO data processing system is composed of several steps for checking observation locations, missing values, physical values for Earth radius of curvature, and geoid undulation. An observation-minus-background check is implemented by use of a one-dimensional observational bending-angle operator, and tangent point drift is also considered in the quality control process. We have tested GPS-RO observations utilized by the Korean Meteorological Administration (KMA) within KPOP, based on both the KMA global model and the National Center for Atmospheric Research Community Atmosphere Model with Spectral Element dynamical core (CAM-SE) as a model background. Background fields from the CAM-SE model are incorporated for the preparation of assimilation experiments with the KIAPS local ensemble transform Kalman filter (LETKF) data assimilation system, which has been successfully implemented to a cubed-sphere model with unstructured quadrilateral meshes. As a result of data processing, the bending-angle departure statistics between observation and background show significant improvement. Also, the first experiment in assimilating GPS-RO bending angle from KPOP within KIAPS-LETKF shows encouraging results.
Implementation of a quality control for radio occultation observations in the presence of large gradients of atmospheric refractivity
Authors: Cucurull L.
Published: March 2015

Abstract. In preparation for the launch of the first six satellites of the COSMIC-2 mission in equatorial orbit, and the larger number of observations that such a mission will provide in the lower tropical troposphere, work is underway at the National Oceanic and Atmospheric Administration (NOAA) to improve the assimilation of radio occultation (RO) observations, particularly in the lower tropical troposphere. As part of the improvement of the bending angle forward operator at the National Centers for Environmental Prediction (NCEP), additional quality controls aimed to detect and reject observations that might have been affected by super-refraction conditions have been implemented and tested. The updated quality control procedures also address the situation where the model detects atmospheric super-refraction conditions. This paper describes the limitations of the current standard quality controls and discusses the implementation of additional quality control procedures to address the limitations of assimilating observations likely affected by the super-refraction conditions, either in the model simulation or in the retrieval process.
Spatiotemporal variability of alkalinity in the Mediterranean Sea
Authors: Cossarini G. , Lazzari P. , Solidoro C.
Published: March 2015

Abstract. The paper provides a basin-scale assessment of the spatiotemporal distribution of alkalinity in the Mediterranean Sea. The assessment is made by integrating the available observations into a 3-D transport–biogeochemical model. The results indicate the presence of complex spatial patterns: a marked west-to-east surface gradient of alkalinity is coupled to secondary negative gradients: (1) from marginal seas (Adriatic and Aegean Sea) to the eastern Mediterranean Sea and (2) from north to south in the western region. The west–east gradient is related to the mixing of Atlantic water entering from the Strait of Gibraltar with the high-alkaline water of the eastern sub-basins, which is correlated to the positive surface flux of evaporation minus precipitation. The north-to-south gradients are related to the terrestrial input and to the input of the Black Sea water through the Dardanelles. In the surface layers, alkalinity has a relevant seasonal cycle (up to 40 μmol kg−1) that is driven by physical processes (seasonal cycle of evaporation and vertical mixing) and, to a minor extent, by biological processes. A comparison of alkalinity vs. salinity indicates that different regions present different relationships: in regions of freshwater influence, the two quantities are negatively correlated due to riverine alkalinity input, whereas they are positively correlated in open sea areas of the Mediterranean Sea.
Disparities between in situ and optically derived carbon biomass and growth rates of the prymnesiophyte Phaeocystis globosa
Authors: Peperzak L. , van der Woerd H. J. , Timmermans K. R.
Published: March 2015

Abstract. The oceans play a pivotal role in the global carbon cycle. It is not practical to measure the global daily production of organic carbon, the product of phytoplankton standing stock and its growth rate using discrete oceanographic methods. Instead, optical proxies from Earth-orbiting satellites must be used. To test the accuracy of optically derived proxies of phytoplankton physiology and growth rate, hyperspectral reflectance data from the wax and wane of a Phaeocystis bloom in laboratory mesocosms were compared with standard ex situ data. Chlorophyll biomass could be estimated accurately from reflectance using specific chlorophyll absorption algorithms. However, the conversion of chlorophyll (Chl) to carbon (C) was obscured by the non-linear increase in C : Chl under nutrient-limited growth. Although C : Chl was inversely correlated (r2 = 0.88) with the in situ fluorometric growth rate indicator Fv / Fm (Photosystem II quantum efficiency), none of them was linearly correlated to growth rate, constraining the accurate calculation of Phaeocystis growth or production rates. Unfortunately, the optical proxy ϕph (quantum efficiency of fluorescence: the ratio of the number of fluoresced photons to the number of photons absorbed by the phytoplankton) did not show any correlation with Phaeocystis growth rate, and therefore it is concluded that ϕph cannot be applied in the remotely sensed measurement of this species' carbon production rate.
Reviews and Syntheses: Responses of coccolithophores to ocean acidification: a meta-analysis
Authors: Meyer J. , Riebesell U.
Published: March 2015

Abstract. Concerning their sensitivity to ocean acidification, coccolithophores, a group of calcifying single-celled phytoplankton, are one of the best-studied groups of marine organisms. However, in spite of the large number of studies investigating coccolithophore physiological responses to ocean acidification, uncertainties still remain due to variable and partly contradictory results. In the present study we have used all existing data in a meta-analysis to estimate the effect size of future pCO2 changes on the rates of calcification and photosynthesis and the ratio of particulate inorganic to organic carbon (PIC / POC) in different coccolithophore species. Our results indicate that ocean acidification has a negative effect on calcification and the cellular PIC / POC ratio in the two most abundant coccolithophore species: Emiliania huxleyi and Gephyrocapsa oceanica. In contrast, the more heavily calcified species Coccolithus braarudii did not show a distinct response when exposed to elevated pCO2/reduced pH. Photosynthesis in Gephyrocapsa oceanica was positively affected by high CO2, while no effect was observed for the other coccolithophore species. There was no indication that the method of carbonate chemistry manipulation was responsible for the inconsistent results regarding observed responses in calcification and the PIC / POC ratio. The perturbation method, however, appears to affect photosynthesis, as responses varied significantly between total alkalinity (TA) and dissolved inorganic carbon (DIC) manipulations. These results emphasize that coccolithophore species respond differently to ocean acidification, both in terms of calcification and photosynthesis. Where negative effects occur, they become evident at CO2 levels in the range projected for this century in the case of unabated CO2 emissions. As the data sets used in this meta-analysis do not account for adaptive responses, ecological fitness and ecosystem interactions, the question remains as to how these physiological responses play out in the natural environment.
Response of CO2 and H2O fluxes of a mountainous tropical rain forest in equatorial Indonesia to El Niño events
Authors: Olchev A. , Ibrom A. , Panferov O. , Gushchina D. , Propastin P. , Kreilein H. , June T. , Rauf A. , Gravenhorst G. , Knohl A.
Published: March 2015

Abstract. The possible impact of El Niño–Southern Oscillation (ENSO) events on the main components of CO2 and H2O fluxes in a pristine mountainous tropical rainforest growing in Central Sulawesi in Indonesia is described. The fluxes were continuously measured using the eddy covariance method for the period from January 2004 to June 2008. During this period, two episodes of El Niño and one episode of La Niña were observed. All these ENSO episodes had moderate intensity and were of Central Pacific type. The temporal variability analysis of the main meteorological parameters and components of CO2 and H2O exchange showed a very high sensitivity of Evapotranspiration (ET) and Gross Primary Production (GPP) of the tropical rain forest to meteorological variations caused by both El Niño and La Niña episodes. Incoming solar radiation is the main governing factor that is responsible for ET and GPP variability. Ecosystem Respiration (RE) dynamics depend mainly on the air temperature changes and are almost insensitive to ENSO. Changes of precipitation due to moderate ENSO events did not cause any notable effect on ET and GPP, mainly because of sufficient soil moisture conditions even in periods of anomalous reduction of precipitation in the region.
Interdependencies between temperature and moisture sensitivities of CO2 emissions in European land ecosystems
Authors: Gritsch C. , Zimmermann M. , Zechmeister-Boltenstern S.
Published: March 2015

Abstract. Soil respiration is one of the largest terrestrial fluxes of carbon dioxide (CO2) to the atmosphere. Hence, small changes in soil respiration rates could have large effects on atmospheric CO2. In order to assess CO2 emissions from diverse European soils under different land-use and climate (soil moisture and temperature) we conducted a laboratory incubation experiment. Emission measurements of carbon dioxide under controlled conditions were conducted using soil monoliths of nine sites from the ÉCLAIRE flux network. Sites are located all over Europe; from the UK in the west to the Ukraine in the east; Italy in the south to Finland in the north and can be separated according to four land-uses (forests, grasslands, arable lands and one peatland). Intact soil cores were incubated in the laboratory at the temperatures 5, 10, 15, 20, and 25 °C in a two factorial design of five soil moisture levels (5, 20, 40, 60, 80 (100)% water filled pore space, WFPS), before analysed for CO2 fluxes with an automated laboratory incubation measurement system. Land-use generally had a substantial influence on carbon dioxide fluxes, with the order of CO2 emission rates of the different land-uses being grassland > peatland > forest/arable land (P < 0.001). CO2 efflux responded strongly to varying temperature and moisture content with optimum moisture contents for CO2 emissions between 40–70% WFPS and a positive relationship between CO2 emissions and temperature. The relationship between temperature and CO2 emissions could be well described by a Gaussian model. Q10 values ranged between 0.86–10.85 and were negatively related to temperature for most of the moisture contents and sites investigated. At higher temperatures the effect of water and temperature on Q10 was very low. In addition under cold temperatures Q10 varied with moisture contents indicating a stronger prospective effect of rain events in cold areas on temperature sensitivity. We found at both coniferous forest sites a strong increase of the temperature sensitivity at a moisture range between 20–40% WFPS. In our study moisture sensitivity (MS) of CO2 efflux was calculated as the slope of a polynomial function of second degree. Moisture sensitivities were highest under dry and wet conditions. In addition we found a positive relationship between MS of CO2 efflux and temperature for both arable lands.
Simultaneous high C fixation and high C emissions in Sphagnum mires
Authors: Harpenslager S. F. , van Dijk G. , Kosten S. , Roelofs J. G. M. , Smolders A. J. P. , Lamers L. P. M.
Published: March 2015

Abstract. Peatlands play an important role in the global carbon (C) cycle due to their large C storage potential. Their C sequestration rates, however, highly vary depending on climatic and geohydrological conditions. Transitional mires are often characterised by floating peat with infiltration of buffered groundwater or surface water. On top, Sphagnum mosses grow, producing recalcitrant organic matter and fuelling the large C stocks. As Sphagnum species strongly differ in their tolerance to the higher pH in these mires, their species composition can be expected to influence C dynamics in transitional mires. We therefore experimentally determined growth and net C sequestration rates for four different Sphagnum species (Sphagnum squarrosum, S. palustre, S. fallax and S. magellanicum) in aquaria, with floating peat influenced by the infiltration of buffered water. Surprisingly, even though the first three species increased their biomass, the moss-covered peat still showed a net efflux of CO2 that was up to three times higher than that of bare peat. This species-dependent C release could be explained by Sphagnum's active lowering of the pH, which triggers the chemical release of CO2 from bicarbonate. Our results clearly illustrate that high Sphagnum biomass production may still coincide with high C emission. These counterintuitive C dynamics in mire succession seem to be the result of both species- and biomass-dependent acidification and buffered water infiltration. Together, these processes can explain part of the large variation in C fluxes (ranging from C sequestration to C release) reported for pristine mires in literature.
Regional climate hindcast simulations within EURO-CORDEX: evaluation of a WRF multi-physics ensemble
Authors: Katragkou E. , García-Díez M. , Vautard R. , Sobolowski S. , Zanis P. , Alexandri G. , Cardoso R. M. , Colette A. , Fernandez J. , Gobiet A. , Goergen K. , Karacostas T. , Knist S. , Mayer S. , Soares P. M. M. , Pytharoulis I. , Tegoulias I. , Tsikerdekis A. , Jacob D.
Published: March 2015

Abstract. In the current work we present six hindcast WRF (Weather Research and Forecasting model) simulations for the EURO-CORDEX (European Coordinated Regional Climate Downscaling Experiment) domain with different configurations in microphysics, convection and radiation for the time period 1990–2008. All regional model simulations are forced by the ERA-Interim reanalysis and have the same spatial resolution (0.44°). These simulations are evaluated for surface temperature, precipitation, short- and longwave downward radiation at the surface and total cloud cover. The analysis of the WRF ensemble indicates systematic temperature and precipitation biases, which are linked to different physical mechanisms in the summer and winter seasons. Overestimation of total cloud cover and underestimation of downward shortwave radiation at the surface, mostly linked to the Grell–Devenyi convection and CAM (Community Atmosphere Model) radiation schemes, intensifies the negative bias in summer temperatures over northern Europe (max −2.5 °C). Conversely, a strong positive bias in downward shortwave radiation in summer over central (40–60%) and southern Europe mitigates the systematic cold bias over these regions, signifying a typical case of error compensation. Maximum winter cold biases are over northeastern Europe (−2.8 °C); this location suggests that land–atmosphere rather than cloud–radiation interactions are to blame. Precipitation is overestimated in summer by all model configurations, especially the higher quantiles which are associated with summertime deep cumulus convection. The largest precipitation biases are produced by the Kain–Fritsch convection scheme over the Mediterranean. Precipitation biases in winter are lower than those for summer in all model configurations (15–30%). The results of this study indicate the importance of evaluating not only the basic climatic parameters of interest for climate change applications (temperature and precipitation), but also other components of the energy and water cycle, in order to identify the sources of systematic biases, possible compensatory or masking mechanisms and suggest pathways for model improvement.
An analytical verification test for numerically simulated convective flow above a thermally heterogeneous surface
Authors: Shapiro A. , Fedorovich E. , Gibbs J. A.
Published: March 2015

Abstract. An analytical solution of the Boussinesq equations for the motion of a viscous stably stratified fluid driven by a surface thermal forcing with large horizontal gradients (step changes) is obtained. The solution can be used to verify that computer codes for Boussinesq fluid system simulations are free of errors in formulation of wall boundary conditions, and to evaluate the relative performances of competing numerical algorithms. Because the solution pertains to flows driven by a surface thermal forcing, one of its main applications may be for testing the no-slip, impermeable wall boundary conditions for the pressure Poisson equation. Examples of such tests are presented.
Improving the representation of fire disturbance in dynamic vegetation models by assimilating satellite data
Authors: Kantzas E. P. , Quegan S. , Lomas M.
Published: March 2015

Abstract. Fire provides an impulsive and stochastic pathway for carbon from the terrestrial biosphere to enter the atmosphere. Despite fire emissions being of similar magnitude to Net Ecosystem Exchange in many biomes, even the most complex Dynamic Vegetation Models (DVMs) embedded in General Circulation Models contain poor representations of fire behaviour and dynamics such as propagation and distribution of fire sizes. A model-independent methodology is developed which addresses this issue. Its focus is on the Arctic where fire is linked to permafrost dynamics and on occasion can release great amounts of carbon from carbon-rich organic soils. Connected Component Labeling is used to identify individual fire events across Canada and Russia from daily, low-resolution burned area satellite products, and the results are validated against historical data. This allows the creation of a fire database holding information on area burned and temporal evolution of fires in space and time. A method of assimilating the statistical distribution of fire area into a DVM whilst maintaining its Fire Return Interval is then described. The algorithm imposes a regional scale spatially dependent fire regime on a sub-scale spatially independent model (point model); the fire regime is described by large scale statistical distributions of fire intensity and spatial extent, and the temporal dynamics (fire return intervals) are determined locally. This permits DVMs to estimate many aspects of post-fire dynamics that cannot occur under their current representations of fire, as is illustrated by considering the evolution of land cover, biomass and Net Ecosystem Exchange after a fire.
Timescales of regional circulation of saline fluids in continental crystalline rock aquifers (Armorican Massif, western France)
Authors: Armandine Les Landes A. , Aquilina L. , Davy P. , Vergnaud-Ayraud V. , Le Carlier C.
Published: March 2015

Abstract. In recent decades, saline fluids have been sampled worldwide at great depths in continental basements. Although some of them have been attributed to marine transgressions, the mechanisms allowing their circulation are not understood. In this paper, we describe the horizontal and vertical distributions of moderately saline fluids (60 to 1400 mg L−1) sampled at depths ranging from 41 to 200 m in crystalline rock aquifers on the regional scale of the Armorican Massif (northwestern France). The horizontal and vertical distributions of high chloride concentrations are in good agreement with both the altitudinal and vertical limits and the succession of the three major transgressions between the Mio-Pliocene and Pleistocene ages. The mean chloride concentration for each transgression area is exponentially related to the time spanned until the present. It defines the potential laws of leaching (displacement) of marine waters by fresh meteoric waters. The results of the Armorican aquifers provide the first observed constraints for the timescales of seawater circulation in the continental crystalline basement and the subsequent leaching by fresh meteoric waters. The general trend of increasing chloride concentration with depth and the time frame for the flushing process provide useful information to develop conceptual models of the paleo-functioning of Armorican aquifers.
On the spatial organization of the ridge slough patterned landscape
Authors: Casey S. T. , Cohen M. J. , Acharya S. , Kaplan D. A. , Jawitz J. W.
Published: March 2015

Abstract. A century of hydrologic modification has altered the physical and biological drivers of landscape processes in the Everglades (southern Florida, USA). Restoring the ridge-slough patterned landscape, a dominant feature of the historical system, is a priority, but requires an understanding of pattern genesis mechanisms. Physical experiments to evaluate alternative pattern formation mechanisms are limited by the time scales of peat accumulation and loss, necessitating model-based comparisons, where support for a particular mechanism is based on model replication of extant patterning and trajectories of degradation. However, multiple mechanisms yield a central feature of ridge-slough patterning (patch elongation in the direction of historical flow), limiting the utility of that characteristic for discriminating among alternatives. Using data from vegetation maps we investigated the statistical features of ridge-slough spatial patterning (ridge density, patch perimeter, elongation, patch-area scaling, and spatial periodicity) to establish rigorous criteria for evaluating model performance, and to inform controls on pattern variation across the contemporary system. Mean water depth explained significant variation in ridge density, total perimeter, and length : width ratios, illustrating significant pattern response to existing hydrologic gradients. Two independent analyses (2-D periodograms and patch size distributions) provide strong evidence against regular patterning, with the landscape exhibiting neither a characteristic wavelength nor a characteristic patch size, both of which are expected under conditions that produce regular patterns. Rather, landscape properties suggest robust scale-free patterning, indicating genesis from the coupled effects of local facilitation and a global negative feedback operating uniformly at the landscape-scale. Critically, this challenges widespread invocation of meso-scale negative feedbacks for explaining ridge-slough pattern origins. These results help discern among genesis mechanisms and provide an improved statistical template against which to compare model outputs, as well as landscape trajectories with future restoration.
The representation of location by regional climate models in complex terrain
Authors: Maraun D. , Widmann M.
Published: March 2015

Abstract. To assess potential impacts of climate change for a specific location, one typically employs climate model simulations at the grid box corresponding to the same geographical location. But based on regional climate model simulations, we show that simulated climate might be systematically displaced compared to observations. In particular in the rain shadow of moutain ranges, a local grid box is therefore often not representative of observed climate: the simulated windward weather does not flow far enough across the mountains; local grid boxes experience the wrong airmasses and atmospheric circulation. In some cases, also the local climate change signal is deteriorated. Classical bias correction methods fail to correct these location errors. Often, however, a distant simulated time series is representative of the considered observed precipitation, such that a non-local bias correction is possible. These findings also clarify limitations of bias correcting global model errors, and of bias correction against station data.
Developing a functional model for cities impacted by a natural hazard: application to a city affected by flooding
Authors: Bambara G. , Peyras L. , Felix H. , Serre D.
Published: March 2015

Abstract. The experience feedback on a crisis that hit a city is frequently used as a "recollection" tool. To capitalize information about an experience feedback from the cities that have been affected by a natural hazard, the authors propose in this study a functional model to model scenarios of city crises. In this model, the city, considered as a complex system, was modelled using a functional analysis method. Based on such modelling, two risk analysis methods (Failure Mode and Effect Analysis and Event Tree Method) were deployed and adjusted. Lastly, a qualitative reasoning model was used for the scenario modelling of the urban crisis. By functional modelling performed on components of the cities, the objective of this model is to replicate the behaviour of a city affected by a crisis, highlighting the sequences of failure and non-failure modes that have operated during the crisis. This model constitutes a means of understanding the functional behaviour in a crisis of cities and capitalization of the experience feedback of the cities affected by crisis. Such functional modelling was deployed in a case study.
Brief Communication: The double layer in the separatrix region during magnetic reconnection
Authors: Guo J. , Yu B.
Published: March 2015

Abstract. With two-dimensional (2-D) particle-in-cell (PIC) simulations we investigate the evolution of the double layer (DL) driven by magnetic reconnection. Our results show that an electron beam can be generated in the separatrix region as magnetic reconnection proceeds. This electron beam could trigger the ion-acoustic instability; as a result, a DL accompanied with electron holes (EHs) can be found during the nonlinear evolution stage of this instability. The spatial size of the DL is about 10 Debye lengths. This DL propagates along the magnetic field at a velocity of about the ion-acoustic speed, which is consistent with the observation results.
Area, elevation and mass changes of the two southernmost ice caps of the Canadian Arctic Archipelago between 1952 and 2014
Authors: Papasodoro C. , Berthier E. , Royer A. , Zdanowicz C. , Langlois A.
Published: March 2015

Abstract. In the far south of the Canadian Arctic Archipelago (CAA), on the Meta Incognita Peninsula (Baffin Island, Nunavut, Canada), the small Grinnell and Terra Nivea ice caps have received little attention compared to the much larger ice masses further north. Their evolution can, however, give valuable information about the impact of the recent Arctic warming at lower latitudes (i.e. 62.5° N). In this paper, we measure historical and recent rates of area, elevation and mass changes of both ice caps using in-situ, airborne and spaceborne datasets. Results show that the Terra Nivea Ice Cap (TNIC) areal extent has decreased by 34% since the late 50s, while the Grinnell Ice Cap (GIC) extent was reduced by 20% since 1952. For both ice caps, rates of area reduction accelerated at the beginning of the 21st century. The glacier-wide mass balance for the GIC was −0.37 ± 0.21 m a−1 water equivalent (w.e.) for the 1952–2014 period, and −0.47 ± 0.16 m a−1 w.e. on the TNIC for the 1958/59–2014 period. More recently, the TNIC has experienced an accelerated rate of mass loss of −1.68 ± 0.36 m a−1 w.e. between 2007 and 2014. This rate is 5.6 times as negative when compared to the 1958/59–2007 period (−0.30 ± 0.19 m a−1 w.e.) and 2 times as negative when compared to the mass balance of other glaciers in the southern parts of Baffin Island over the 2003–2009 period. A similar acceleration in mass loss is suspected for the GIC, given the calculated elevation changes and the proximity.
Faculty burnout in a large department of pediatrics
Authors: Davis B.H. , Hill S.E.M. , Fisher P. , Nick T. , Ward Wendy L.
Published: March 2015

Background: Physician stress is at a heightened level in the midst of a changing health care environment and limited research funding conditions. Burnout of physicians has an impact on their personal health, related institutional health care costs, retention of quality faculty, and patient care and safety. The present study was designed to assess levels of burnout and sources of stress in clinical, educational, and research faculty working in a Department of Pediatrics and a large Children’s Hospital setting.Methods: The self-report Maslach Burnout Inventory was given to the 240 faculty members in a large Department of Pediatrics based at a Children’s Hospital as part of a larger faculty development needs survey designed to inform faculty development programming. Participation in the survey was voluntarily, and was presented during a mandatory faculty meeting and then emailed to all faculty so those who were unable to attend could participate. A brief survey on sources of stress, stress-related illness, and wellness programming needs was also administered.Results: Out of the 240 faculty members, 86 surveys were collected and analyzed (36% response rate). 52% were female, 84% were Caucasian. Rank of respondents appeared fairly consistent with overall Departmental distribution (40% Assistant, 22% Associate, 34% Full, 4% Instructor). 48% of respondents were Clinical Educators, with 18% Basic Scientists, 17% Clinical Attendings, and 16% Clinical Scientists, also fairly consistent with overall Departmental distributions. Results suggest 65% of faculty endorse high levels of emotional exhaustion, 56% high levels of depersonalization, and 100% felt low levels of personal accomplishment. According to Maslach Burnout Inventory (MBI) cutoff criteria, 94% of respondents were above the cutoff for Burnout, much higher than recent, published national norms. The most frequently identified top stressors were: lack of connectedness to the institution, administrative responsibilities, time conflicts, clinical workload and general workload. The most frequently identified top stress symptoms experienced were: mood issues, health-related behaviors, and psychosomatic symptoms.Conclusions: Burnout rates at this institution are higher than national norms. From the data collected, faculty development programs to address coping with burnout and prevention such as strategies to promote resilience to stress will be provided. Faculty will be periodically provided with currently available sources of individual and group support and these will be easily available on the internal website. Institutional changes that may affect burnout rates should also be considered.
Design and Control of a Powered Hip Exoskeleton for Walking Assistance
Authors: Wu Qingcong , Wang Xingsong , Du Fengpo , Zhang Xiaobo
Published: March 2015

The wearable powered exoskeleton is a human-robot cooperation system that integrates the strength of a robot with human intelligence. This paper presents the research results into a powered hip exoskeleton (PH-EXOS) designed to provide locomotive assistance to individuals with walking impediments. The Bowden cable actuated exoskeleton has an anthropomorphic structure with six degrees of freedom (DOF) in order to match the human hip anatomy and enable natural interaction with the user. The mechanical structure, the actuation system, and the interaction kinematics of PH-EXOS are optimized to achieve preferable manoeuvrability and harmony. For the control of the exoskeleton, a real-time control system is established in xPC target environment based on Matlab/RTW. A Cascaded PID controller is developed to perform the trajectories tracking tasks in passive control mode. Besides, based on the pressure information on the thigh, a fuzzy adaptive controller is developed to perform walking assistance tasks in active control mode. Preliminary treadmill walking experiments on a healthy subject were conducted to verify the effectiveness of the proposed device and control approaches in reducing walking effort.