bluuebunny/crossref_metadata_2025 huggingface dataset:
Precipitation Hardening on Mechanical and Corrosion Properties of Extruded Mg10Gd Modified with Nd and La
Authors: Maier Petra , Bechly Maximilian , Mendis Chamini L. , Hort Norbert
Published: August 2018

To improve the mechanical and corrosion properties of Mg10Gd, Nd and La are added, and from that, the influence of precipitation hardening was studied. An increase in strength, by decreasing grain size and increasing the volume fraction of Rare Earth-rich precipitates, has been found when increasing the amount of alloying elements. Alloys containing La appear less ductile. Where crack propagation is studied using 3-point bending on Mg10Gd and Mg10Gd1Nd, the failure is mostly driven by twinning; the alloys with La show suppressed twinning, but crack initiation and propagation is caused by brittle and coarse precipitates. Precipitation hardening did not improve fracture toughness and was mostly based on strong grain growth and low solubility of La in Mg. With added alloying elements, the grain size was found to be slightly smaller in the T6 condition—precipitates seem to pin grain boundaries and therefore limit grain boundary mobility. Alloys containing Nd showed the best precipitation hardening response. Corrosion behavior, investigated by voltammetry and immersion, showed the best behavior in the precipitation-hardened condition. Corrosion rates and surface morphology are used to discuss corrosion properties.
Core-Shell Structures of Upconversion Nanocrystals Coated with Silica for Near Infrared Light Enabled Optical Imaging of Cancer Cells
Authors: Lingeshwar Reddy Kumbam , Prabhakar Neeraj , Rosenholm Jessica M. , Krishnan Venkata
Published: August 2018

Optical imaging of cancer cells using near infrared (NIR) light is currently an active area of research, as this spectral region directly corresponds to the therapeutic window of biological tissues. Upconversion nanocrystals are photostable alternatives to conventional fluorophores. In our work, we have prepared upconversion nanocrystals of NaYF4:Yb/Er and encapsulated them in silica to form core-shell structures. The as-prepared core-shell nanostructures have been characterized for their structure, morphology, and optical properties using X-ray diffraction, transmission electron microscopy coupled with elemental mapping, and upconversion luminescence spectroscopy, respectively. The cytotoxicity examined using cell viability assay indicated a low level of toxicity of these core-shell nanostructures. Finally, these core-shell nanostructures have been utilized as photostable probes for NIR light enabled optical imaging of human breast cancer cells. This work paves the way for the development of advanced photostable, biocompatible, low-toxic core-shell nanostructures for potential optical imaging of biological cells and tissues.
Evaluation of Viscosity, Strength and Microstructural Properties of Cemented Tailings Backfill
Authors: Cao Shuai , Yilmaz Erol , Song Weidong
Published: August 2018

In this study, the particle size distribution and chemical composition of gold mine tailings were examined experimentally. A series of viscosity and uniaxial compressive strength (UCS) tests were used to study the relations between the viscosity of cemented tailings backfill (CTB) slurry, the solid content (SD), and the cement-to-tailings ratio (c/t). Relations between UCS performance of CTB and SD, c/t, and curing time (CT) were discussed while examining the microstructure of 28-day cured backfill with different solid contents. Results illustrate that a major increase in CTB viscosity by increasing the SD leads to the formation of tailings grains for a skeleton formation, which is formed due to consolidation and gravitational forces. The CTB’s strength increases with the increase of c/t, SD, and CT, due to a decrease in water-to-cement ratio and porosity, and an increase in hydration products over time. The SEM micrographs show how CTB’s microstructure is affected by the SD, generating ettringites and calcium silicate hydrates in the backfill matrix. The findings of this study will lead to an efficient CTB mix design for reaching the higher performance in underground mining structures, thereby reducing expenses related to the backfill.
Effect of Different Anthocyanidin Glucosides on Lutein Uptake by Caco-2 Cells, and Their Combined Activities on Anti-Oxidation and Anti-Inflammation In Vitro and Ex Vivo
Authors: Phan Minh Anh Thu , Bucknall Martin , Arcot Jayashree
Published: August 2018

The interactive effects on anti-oxidation and anti-inflammation of lutein combined with each of the six common anthocyanidin glucosides were studied in both chemical and cellular systems. The combined phytochemicals showed an antagonism in the inhibition of lipid oxidation in a liposomal membrane, but showed an additive effect on cellular antioxidant activity in Caco-2 cells. Lutein was an active lipoxygenase inhibitor at 2–12 μM while anthocyanins were inactive. The concentration of lutein when it was used in combination with anthocyanins was 25–54% higher than when lutein was used alone (i.e., IC50 = 1.2 μM) to induce 50% of lipoxygenase inhibition. Only the combination of lutein with malvidin-3-glucoside showed anti-inflammatory synergy in the suppression of interleukin-8, and the synergy was seen at all three ratios tested. Some mixtures, however, showed anti-inflammatory antagonism. The presence of anthocyanins (5–7.5 μM) did not affect lutein uptake (2.5–5 μM) by Caco-2 cells.
Synthesis of Small Ce3+-Er3+-Yb3+ Tri-Doped BaLuF5 Active-Core-Active-Shell-Active-Shell Nanoparticles with Strong Down Conversion Luminescence at 1.5 μm
Authors: Zhang Yongling , Shi Yudi , Qin Zhengkun , Song Mingxing , Qin Weiping
Published: August 2018

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach to improve 1.5 μm emission of BaLuF5:Yb3+,Er3+ NPs by way of combining doping Ce3+ ions and coating multiple BaLuF5: Yb3+ active-shells. We prepared the BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs through a high-boiling solvent method. The effect of Ce3+ concentration on the DC luminescence was systematically investigated in the BaLuF5:Yb3+,Er3+ NPs. Under a 980 nm laser excitation, the intensities of 1.53 μm emission of BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs was enhanced by 2.6 times comparing to that of BaLuF5:18%Yb3+,2%Er3+ NPs since the energy transfer between Er3+ and Ce3+ ions: Er3+:4I11/2 (Er3+) + 2F5/2 (Ce3+) → 4I13/2 (Er3+) + 2F7/2 (Ce3+). Then, we synthesized BaLuF5:18%Yb3+,2%Er3+,2%Ce3+@BaLuF5:5%Yb3+@BaLuF5:5%Yb3+ core-active-shell-active-shell NPs via a layer-by-layer strategy. After coating two BaLuF5:Yb3+ active-shell around BaLuF5:Yb3+,Er3+,Ce3+ NPs, the intensities of the 1.53 μm emission was enhanced by 44 times compared to that of BaLuF5:Yb3+,Er3+ core NPs, since the active-shells could be used to not only suppress surface quenching but also to transfer the pump light to the core region efficiently through Yb3+ ions inside the active-shells.
Release of Trace Elements from Bottom Ash from Hazardous Waste Incinerators
Authors: Dung Tran Thi Thu , Vassilieva Elvira , Swennen Rudy , Cappuyns Valérie
Published: August 2018

Bottom ash is the major by-product of waste incineration and can contain trace elements (As, Cd, Co, Cu, Cr, Mo, Ni, Pb, and Zn) with concentrations up to thousands of mg·k−1. In this study, a combination of different extractions and leaching tests (i.e., CH3COOH and ammonium-EDTA (Ethylenediaminetetraacetic acid) extractions and pHstat leaching tests) was used to investigate the potential release of trace elements from bottom ash samples derived from hazardous waste incineration plants. Although large variations have been found in the release of trace elements by different extractions, in general, the highest concentrations of most trace elements (except As and Mo) were released with the CH3COOH extraction, whereas the release of As and Mo was highest with the ammonium-EDTA extraction. Kinetics of element release upon acidification based on a pHstat leaching test at pH 4 could be related to the solid-phase speciation of some selected trace elements. The relatively high-potential mobility and elevated total concentrations of some trace elements imply a threat to the environment if these bottom ashes are not treated properly. Results of the present study may be useful to develop potential treatment strategies to remove contaminants and eventually recover metals from bottom ash.
SLALOM: An All-Surface Snow Water Path Retrieval Algorithm for the GPM Microwave Imager
Authors: Rysman Jean-François , Panegrossi Giulia , Sanò Paolo , Marra Anna , Dietrich Stefano , Milani Lisa , Kulie Mark
Published: August 2018

This paper describes a new algorithm that is able to detect snowfall and retrieve the associated snow water path (SWP), for any surface type, using the Global Precipitation Measurement (GPM) Microwave Imager (GMI). The algorithm is tuned and evaluated against coincident observations of the Cloud Profiling Radar (CPR) onboard CloudSat. It is composed of three modules for (i) snowfall detection, (ii) supercooled droplet detection and (iii) SWP retrieval. This algorithm takes into account environmental conditions to retrieve SWP and does not rely on any surface classification scheme. The snowfall detection module is able to detect 83% of snowfall events including light SWP (down to 1 × 10−3 kg·m−2) with a false alarm ratio of 0.12. The supercooled detection module detects 97% of events, with a false alarm ratio of 0.05. The SWP estimates show a relative bias of −11%, a correlation of 0.84 and a root mean square error of 0.04 kg·m−2. Several applications of the algorithm are highlighted: Three case studies of snowfall events are investigated, and a 2-year high resolution 70°S–70°N snowfall occurrence distribution is presented. These results illustrate the high potential of this algorithm for snowfall detection and SWP retrieval using GMI.
Crop Classification in a Heterogeneous Arable Landscape Using Uncalibrated UAV Data
Authors: Böhler Jonas E. , Schaepman Michael E. , Kneubühler Mathias
Published: August 2018

Land cover maps are indispensable for decision making, monitoring, and management in agricultural areas, but they are often only available after harvesting. To obtain a timely crop map of a small-scale arable landscape in the Swiss Plateau, we acquired uncalibrated, very high-resolution data, with a spatial resolution of 0.05 m and four spectral bands, using a consumer-grade camera on an unmanned aerial vehicle (UAV) in June 2015. We resampled the data to different spatial and spectral resolutions, and evaluated the method using textural features (first order statistics and mathematical morphology), a random forest classifier for best performance, as well as number and size of the structuring elements. Our main findings suggest the overall best performing data consisting of a spatial resolution of 0.5 m, three spectral bands (RGB—red, green, and blue), and five different sizes of the structuring elements. The overall accuracy (OA) for the full set of crop classes based on a pixel-based classification is 66.7%. In case of a merged set of crops, the OA increases by ~7% (74.0%). For an object-based classification based on individual field parcels, the OA increases by ~20% (OA of 86.3% for the full set of crop classes, and 94.6% for the merged set, respectively). We conclude the use of UAV to be most relevant at 0.5 m spatial resolution in heterogeneous arable landscapes when used for crop classification.
Flood Prevention and Emergency Response System Powered by Google Earth Engine
Authors: Liu Cheng-Chien , Shieh Ming-Chang , Ke Ming-Syun , Wang Kung-Hwa
Published: August 2018

This paper reviews the efforts made and experiences gained in developing the Flood Prevention and Emergency Response System (FPERS) powered by Google Earth Engine, focusing on its applications at the three stages of floods. At the post-flood stage, FPERS integrates various remote sensing imageries, including Formosat-2 optical imagery to detect and monitor barrier lakes, synthetic aperture radar imagery to derive an inundation map, and high-spatial-resolution photographs taken by unmanned aerial vehicles to evaluate damage to river channels and structures. At the pre-flood stage, a huge amount of geospatial data are integrated in FPERS and are categorized as typhoon forecast and archive, disaster prevention and warning, disaster events and analysis, or basic data and layers. At the during-flood stage, three strategies are implemented to facilitate the access of the real-time data: presenting the key information, making a sound recommendation, and supporting the decision-making. The example of Typhoon Soudelor in August of 2015 is used to demonstrate how FPERS was employed to support the work of flood prevention and emergency response from 2013 to 2016. The capability of switching among different topographic models and the flexibility of managing and searching data through a geospatial database are also explained, and suggestions are made for future works.
A Ceramic Diffusion Bonding Method for Passive LC High-Temperature Pressure Sensor
Authors: Li Chen , Sun Boshan , Xue Yanan , Xiong Jijun
Published: August 2018

Alumina ceramic is a highly promising material for fabricating high-temperature pressure sensors. In this paper, a direct bonding method for fabricating a sensitive cavity with alumina ceramic is presented. Alumina ceramic substrates were bonded together to form a sensitive cavity for high-temperature pressure environments. The device can sense pressure parameters at high temperatures. To verify the sensitivity performance of the fabrication method in high-temperature environments, an inductor and capacitor were integrated on the ceramic substrate with the fabricated sensitive cavity to form a wireless passive LC pressure sensor with thick-film integrated technology. Finally, the fabricated sensor was tested using a system test platform. The experimental results show that the sensor can realize pressure measurements above 900 °C, confirming that the fabricated sensitive cavity has excellent sealing properties. Therefore, the direct bonding method can potentially be used for developing all-ceramic high-temperature pressure sensors for application in harsh environments.
Procedure Negligence in Coastal Cargo: What Can Be Done to Reduce the Gap between Formal and Informal Aspects of Safety?
Authors: Nævestad Tor-Olav , Vedal Størkersen Kristine , Phillips Ross O.
Published: August 2018

Previous studies from the coastal cargo sector report of a considerable gap between formal and informal aspects of safety. Several maritime accident investigations point to this gap as an important contributory cause, indicating that risk increases when informal practices ignore or violate formal procedures. The main aims of this paper are therefore to examine the factors influencing procedure negligence in the coastal cargo sector, and to discuss how to reduce the gap between formal and informal aspects of safety. The study is based on quantitative survey results of 180 crewmembers and qualitative research interviews with 10 leading officers on cargo vessels sailing along the coast of Norway. Survey results indicate that procedure negligence is related to work pressure and demanding working conditions. It is also related to outcome measures like personal injuries and perceptions of risk and safety. A positive organizational safety culture is experienced by respondents reporting of less procedure negligence. Interview results indicate, for example, that formal procedures are ignored or violated because of issues like efficiency demands and low-quality procedures, and that procedures more often are followed when they are perceived as useful and timely. In this article, it is thus suggested that a positive safety culture includes an alignment of formal and informal aspects of safety, which requires time to comply with practical procedures. Interviewees suggest that appropriate procedures are: (1) developed by the users, (2) continuously improved, (3) simplified, and (4) supervised by local expertise instead of general experts.
Evaluation of the Physical, Chemical and Thermal Properties of Portuguese Maritime Pine Biomass
Authors: Filipe dos Santos Viana Helder , Martins Rodrigues Abel , Godina Radu , Carlos de Oliveira Matias João , Jorge Ribeiro Nunes Leonel
Published: August 2018

A characterisation of Pinus pinaster Aiton. (Maritime Pine) woody biomass and ashes is presented in this study. Physical, thermal and chemical analysis, including density, moisture content, calorific value, proximate and ultimate analysis, were carried out. The fuel Energy Density (Ed) and the Fuelwood Value Index (FVI) were assessed by ranking the fuelwood quality. Furthermore, the determination of the ash metal elementals was performed. The results from this study indicated, for Pinus pinaster biomass tree components, carbon content ranging from 46.5 to 49.3%, nitrogen content from 0.13 to 1.18%, sulphur content from 0.056 to 0.148% and hydrogen content around 6–7%. The ash content in the tree components ranged from 0.22 to 1.92%. The average higher heating value (HHV) was higher for pine needles (21.61 MJ·kg−1). The Ed of 8.9 GJ·m−3 confirm the good potential of Pinus pinaster biomass tree components as fuel. The FVI ranked the wood stem (4658) and top (2861.8) as a better fuelwood and pine needles (394.2) as inferior quality. The chemical composition of the ashes revealed that the elemental contents are below the national and most European countries legislation guidelines for the employment of ash as a fertiliser.
On the Necessity of Banning the Term “Heavy Metal” from the Scientific Literature
Authors: Pourret Olivier
Published: August 2018

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Application of Anticoincidence Technology to Burn-Up Measurement Systems in High-Temperature Gas-Cooled Reactors
Authors: Mao Cui , Liu Yi-Bao , Zhang Li-Guo
Published: August 2018

Nuclear energy is the focus of sustainable energy development worldwide. A high-temperature gas-cooled reactor (HTGR) plays a vital role in the development of nuclear energy. In a pebble-bed HTGR, the burn-up measurement system is important for ensuring reactor safety and economy. This study optimized a burn-up measurement system by adding anticoincidence technology with bismuth germanium oxide (BGO) crystals and a plastic scintillator used as anticoincidence detectors. Through Monte Carlo simulation, the detection effects of two different anticoincidence detectors on fuel elements were compared and analyzed. The study focused on varying the wall thickness and top thickness of these detectors to optimize the peak-to-Compton ratio (P/C). The results showed that the size of the BGO detector with the best anticoincidence effect (P/C of 727) consists in a diameter of 140 mm and a length of 210 mm. The best plastic scintillator size (P/C of 180) consists in a diameter of 260 mm and a length of 260 mm. Adding the anticoincidence technology lowered the Compton plateau of the measured gamma spectrum and significantly improved the detection performance of the burn-up measurement system. The new burn-up measurement system has improved detection precision not only for Cs-137 but also for low-activity nuclides.
Ex-Ante Analysis of Economic, Social and Environmental Impacts of Large-Scale Renewable and Nuclear Energy Targets for Global Electricity Generation by 2030
Authors: Almutairi Kamel , Thoma Greg , Durand-Morat Alvaro
Published: August 2018

This study assesses the economic, social and environmental impacts of renewable and nuclear energy targets for global electricity generation by 2030. It examines different regions, as they might experience different impacts depending on the structures of their economies and their local natural resources, to understand the impact of these targets on their economics and well-being of their people. These regions are: Saudi Arabia, the United States (US), China, India, Europe and Rest of World (ROW). A well-known Computable General Equilibrium (CGE) model, the Global Trade Analysis Project (GTAP), is modified and used to predict global economic shifts that would be triggered by two scenarios. The business as usual (BAU) scenario assumes that the current electricity mix remains unchanged until 2030. The Renewable and Nuclear Energy (RNE) scenario is based on the International Energy Outlook (IEO) 2016 prediction. The analysis shows that the GDP value of all regions, except India, is affected negatively. The study shows a loss of 4.45 million jobs worldwide in the RNE compared to the BAU. Finally, the implementation of planned renewable and nuclear energy slightly benefits the environment but not enough to mitigate rise in global temperature.
Developing and Validating an Individual Sustainability Instrument with Engineering Students to Motivate Intentional Change
Authors: Barrella Elise , Spratto Elisabeth Pyburn , Pappas Eric , Nagel Robert
Published: August 2018

This paper describes three studies that were conducted sequentially for purposes of validating the Individual Sustainability survey for use with undergraduate engineering students. During the first study, researchers administered the original 50-item Individual Sustainability survey to an undergraduate engineering class at a mid-sized University, using real and ideal self. Following exploratory and confirmatory factor analysis, the survey instrument was reduced to 36 items, and reframed to compare real self to ideal professional engineer. The new version was administered to three cohorts of engineering students at the same institution, and factor structures were analyzed again. In order to provide more stable parameter estimates, a third study with 34 items was run with engineering students in similar courses at four different institutions. The methods and results of all three studies are described, to justify the survey’s evolution. This is followed by a discussion of the final survey instrument and approaches for administering the survey to undergraduate engineering students, or adapting survey administration for other student populations. The instrument, in its current form, is an effective way to identify dissonance between one’s real and ideal conceptualizations of self, and help individual students identify opportunities for personal change and professional growth toward sustainability values and behaviors.
Stochastic Electric Vehicle Network Considering Environmental Costs
Authors: Ma Jie , Cheng Lin , Li Dawei , Tu Qiang
Published: August 2018

In recent years, many countries have published their timetables to promote electric vehicles. Many researches have focused on the benefits of electric vehicles. Compared with gas vehicles, electric vehicles are more suitable for modern cities, because they are considered to be environment-friendly by the public. Hence we pay attention to the environmental costs of electric vehicles. In this paper, an electric vehicle network is established. To analyze this electric vehicle network, we define environmental costs for the network and propose a stochastic user equilibrium model to describe drivers’ route choice behavior. An algorithm is proposed to solve this model. The model and the algorithm are illustrated through a numerical example. We test the calculation feasibility of the proposed model and the computational efficiency of the proposed algorithm via this numerical example. A comparative analysis is conducted to show the benefits of introducing electric vehicles into traffic networks. With the sensitivity analysis, we also reveal the relationship between people’s environmental awareness, the quantity of electric vehicles and the environmental costs of the overall traffic network.
A Novel Sensitive Cell-Based Immunoenzymatic Assay for Palytoxin Quantitation in Mussels
Authors: Pelin Marco , Sosa Silvio , Brovedani Valentina , Fusco Laura , Poli Mark , Tubaro Aurelia
Published: August 2018

The marine algal toxin palytoxin (PLTX) and its analogues are some of the most toxic marine compounds. Their accumulation in edible marine organisms and entrance into the food chain represent their main concerns for human health. Indeed, several fatal human poisonings attributed to these compounds have been recorded in tropical and subtropical areas. Due to the increasing occurrence of PLTX in temperate areas such as the Mediterranean Sea, the European Food Safety Authority (EFSA) has suggested a maximum limit of 30 µg PLTX/kg in shellfish meat, and has recommended the development of rapid, specific, and sensitive methods for detection and quantitation of PLTX in seafood. Thus, a novel, sensitive cell-based ELISA was developed and characterized for PLTX quantitation in mussels. The estimated limits of detection (LOD) and quantitation (LOQ) were 1.2 × 10−11 M (32.2 pg/mL) and 2.8 × 10−11 M (75.0 pg/mL), respectively, with good accuracy (bias = 2.5%) and repeatability (15% and 9% interday and intraday relative standard deviation of repeatability (RSDr), respectively). Minimal interference of 80% aqueous methanol extract allows PLTX quantitation in mussels at concentrations lower than the maximum limit suggested by EFSA, with an LOQ of 9.1 µg PLTX equivalent/kg mussel meat. Given its high sensitivity and specificity, the cell-based ELISA should be considered a suitable method for PLTX quantitation.
Removal of the N-Glycosylation Sequon at Position N116 Located in p27 of the Respiratory Syncytial Virus Fusion Protein Elicits Enhanced Antibody Responses after DNA Immunization
Authors: Leemans Annelies , Boeren Marlies , Van der Gucht Winke , Pintelon Isabel , Roose Kenny , Schepens Bert , Saelens Xavier , Bailey Dalan , Martinet Wim , Caljon Guy , Maes Louis , Cos Paul , Delputte Peter
Published: August 2018

Prevention of severe lower respiratory tract infections in infants caused by the human respiratory syncytial virus (hRSV) remains a major public health priority. Currently, the major focus of vaccine development relies on the RSV fusion (F) protein since it is the main target protein for neutralizing antibodies induced by natural infection. The protein conserves 5 N-glycosylation sites, two of which are located in the F2 subunit (N27 and N70), one in the F1 subunit (N500) and two in the p27 peptide (N116 and N126). To study the influence of the loss of one or more N-glycosylation sites on RSV F immunogenicity, BALB/c mice were immunized with plasmids encoding RSV F glycomutants. In comparison with F WT DNA immunized mice, higher neutralizing titres were observed following immunization with F N116Q. Moreover, RSV A2-K-line19F challenge of mice that had been immunized with mutant F N116Q DNA was associated with lower RSV RNA levels compared with those in challenged WT F DNA immunized animals. Since p27 is assumed to be post-translationally released after cleavage and thus not present on the mature RSV F protein, it remains to be elucidated how deletion of this glycan can contribute to enhanced antibody responses and protection upon challenge. These findings provide new insights to improve the immunogenicity of RSV F in potential vaccine candidates.
Overview of Trends in the Application of Metagenomic Techniques in the Analysis of Human Enteric Viral Diversity in Africa’s Environmental Regimes
Authors: Osunmakinde Cecilia , Selvarajan Ramganesh , Sibanda Timothy , Mamba Bhekie , Msagati Titus
Published: August 2018

There has been an increase in the quest for metagenomics as an approach for the identification and study of the diversity of human viruses found in aquatic systems, both for their role as waterborne pathogens and as water quality indicators. In the last few years, environmental viral metagenomics has grown significantly and has enabled the identification, diversity and entire genome sequencing of viruses in environmental and clinical samples extensively. Prior to the arrival of metagenomics, traditional molecular procedures such as the polymerase chain reaction (PCR) and sequencing, were mostly used to identify and classify enteric viral species in different environmental milieu. After the advent of metagenomics, more detailed reports have emerged about the important waterborne viruses identified in wastewater treatment plant effluents and surface water. This paper provides a review of methods that have been used for the concentration, detection and identification of viral species from different environmental matrices. The review also takes into consideration where metagenomics has been explored in different African countries, as well as the limitations and challenges facing the approach. Procedures including sample processing, experimental design, sequencing technology, and bioinformatics analysis are discussed. The review concludes by summarising the current thinking and practices in the field and lays bare key issues that those venturing into this field need to consider and address.
Nitrogen and Phosphorus Uptake Dynamics in Tropical Cerrado Woodland Streams
Authors: Reinaldo Finkler Nícolas , Tromboni Flavia , Boëchat Iola Gonçalves , Gücker Björn , Gasparini Fernandes Cunha Davi
Published: August 2018

Pollution abatement through phosphorus and nitrogen retention is a key ecosystem service provided by streams. Human activities have been changing in-stream nutrient concentrations, thereby altering lotic ecosystem functioning, especially in developing countries. We estimated nutrient uptake metrics (ambient uptake length, areal uptake rate, and uptake velocity) for nitrate (NO3–N), ammonium (NH4–N), and soluble reactive phosphorus (SRP) in four tropical Cerrado headwater streams during 2017, through whole-stream nutrient addition experiments. According to multiple regression models, ambient SRP concentration was an important explanatory variable of nutrient uptake. Further, best models included ambient NO3–N and water velocity (for NO3–N uptake metrics), dissolved oxygen (DO) and canopy cover (for NH4–N); and DO, discharge, water velocity, and temperature (for SRP). The best kinetic models describing nutrient uptake were efficiency-loss (R2 from 0.47–0.88) and first-order models (R2 from 0.60–0.85). NO3–N, NH4–N, and SRP uptake in these streams seemed coupled as a result of complex interactions of biotic P limitation, abiotic P cycling processes, and the preferential uptake of NH4–N among N-forms. Global change effects on these tropical streams, such as temperature increase and nutrient enrichment due to urban and agricultural expansion, may have adverse and partially unpredictable impacts on whole-stream nutrient processing.
Water Stewardship: Attributes of Collaborative Partnerships between Mining Companies and Communities
Authors: Fraser Jocelyn , Kunz Nadja C.
Published: August 2018

With many of the world’s largest mines operating in jurisdictions of water scarcity, competition for water has become a frequent source of tension between mining companies and other water users. Water stewardship is, therefore, becoming an important strategy for the mining sector to address stakeholder concerns and earn social acceptance. Collaborative partnerships between mining and other water users are a necessary component of advancing water stewardship, but the attributes needed to implement a successful water stewardship strategy are understudied. This paper addresses this gap by examining two exploratory case studies in Peru and Mongolia, where collaboration has been used as a strategy for promoting more sustainable outcomes in water-scarce regions. The findings suggest that while questions remain about who is best suited to lead collaborative partnerships, trust in the entity responsible for leading collaborative partnerships (especially in situations of high conflict) and a willingness to allow each partner to play to their strengths are critical attributes of success. We conclude that the outcome of collective action between mining companies and other water users offers the potential to deliver both business and social value, and to advance more sustainable water management.
The Large-scale Interstellar Medium of SS 433/W50 Revisited
Authors: Su Yang , Zhou Xin , Yang Ji , Chen Yang , Chen Xuepeng , Zhang Shaobo
Published: August 2018

With new high-resolution CO and H i data, we revisited the large-scale interstellar medium (ISM) environment toward the SS 433/W50 system. We find that two interesting molecular cloud (MC) concentrations, G39.315−1.155 and G40.331−4.302, are well aligned along the precession cone of SS 433 within a smaller opening angle of ∼±7°. The kinematic features of the two MCs at ∼73–84 km s−1, as well as those of the corresponding atomic-gas counterparts, are consistent with the kinematic characteristics of SS 433. That is, the receding gas from SS 433 jet is probably responsible for the redshifted feature of G39.315−1.155 near the Galactic plane, and the approaching one may power the blueshifted gas of G40.331−4.302 toward the observer. Moreover, the H i emission at V
LSR ∼ 70–90 km s−1 displays the morphological resemblance with the radio nebula W50. We suggest that the V
LSR = 77 ± 5 km s−1 gas is physically associated with SS 433/W50, leading to a near kinematic distance of 4.9 ± 0.4 kpc for the system. The observed gas features, which are located outside the current radio boundaries of W50, are probably the fossil record of jet–ISM interactions at ∼105 years ago. The energetic jets of the unique microquasar have profound effects on its ISM environment, which may facilitate the formation of molecular gas on the timescale of ≲0.1 Myr for the ram pressure of ∼2 × 106 K cm−3.
Observations of Two Successive EUV Waves and Their Mode Conversion
Authors: Chandra Ramesh , Chen P. F. , Joshi Reetika , Joshi Bhuwan , Schmieder Brigitte
Published: August 2018

In this paper, we present the observations of two successive fast-mode extreme ultraviolet (EUV) wave events observed on 2016 July 23. Both fast-mode waves were observed by the Atmospheric Imaging Assembly instrument on board the Solar Dynamics Observatory satellite, with a traveling speed of ≈675 and 640 km s−1, respectively. These two wave events were associated with two filament eruptions and two GOES M-class solar flares from the NOAA active region 12565, which was located near the western limb. The EUV waves mainly move toward the south direction. We observed the interaction of the EUV waves with a helmet streamer further away to the south. When either or one of the EUV waves penetrates into the helmet streamer, a slowly propagating wave with a traveling speed of ≈150 km s−1 is observed along the streamer. We suggest that the slowly moving waves are slow-mode waves, and interpret this phenomenon as the magnetohydrodynamic wave-mode conversion from the fast mode to the slow mode. Furthermore, we observed several stationary fronts to the north and south of the source region.
Abundances of Ordinary Chondrites in Thermally Evolving Planetesimals
Authors: Wakita Shigeru , Hasegawa Yasuhiro , Nozawa Takaya
Published: August 2018

Chondrites are some of the most primitive objects in the solar system, and they maintain a record of the degree of thermal metamorphism experienced in their parent bodies. This thermal history can be classified by the petrologic type. We investigate the thermal evolution of planetesimals to account for the current abundances (known as the fall statistics) of petrologic types 3–6 of ordinary chondrites. We carry out a number of numerical calculations in which formation times and sizes of planetesimals are taken as parameters. We find that planetesimals that form within 2.0 Myr after the formation of Ca-Al-rich inclusions (CAIs) can contain all petrologic types of ordinary chondrites. Our results also indicate that plausible scenarios of planetesimal formation, which are consistent with the fall statistics, are that planetesimals with radii larger than 60 km start to form around 2.0 Myr after CAIs and/or that ones with radii less than 50 km should be formed within 1.5 Myr after CAIs. Thus, thermal modeling of planetesimals is important for revealing the occurrence and amount of metamorphosed chondrites and for providing invaluable insights into planetesimal formation.
Leptonic and Hadronic Modeling of Fermi-LAT Hard Spectrum Quasars and Predictions for High-energy Polarization
Authors: Paliya Vaidehi S. , Zhang Haocheng , Böttcher Markus , Ajello M. , Domínguez A. , Joshi M. , Hartmann D. , Stalin C. S.
Published: August 2018

We present the results of a study of the time-averaged spectral energy distributions (SEDs) of eight flat spectrum radio quasars (FSRQs) present in the second catalog of high energy sources detected beyond 50 GeV by the Fermi Large Area Telescope (2FHL). Both leptonic and hadronic scenarios are adopted to explain the multiwavelength SEDs and we find them to be marginally consistent with the 2FHL spectra above 50 GeV. We derive the expected degree of X-ray and γ-ray polarizations both for the average and elevated activity states and note that (i) a hadronic radiative model consistently predicts a higher degree of high energy polarization compared to leptonic ones and (ii) the X-ray polarization degree is higher than the γ-ray polarization in the leptonic scenario, but similar to the γ-ray polarization if the observed radiation is powered by hadronic processes. From the leptonic modeling, the location of the γ-ray emitting region is found to be at the outer edge of the broad line region (BLR) and is consistent with the γγ opacity estimates for the γ-ray absorption by the BLR. We conclude that a majority of the FSRQs could be detected by the upcoming Cherenkov Telescope Array, though future high energy polarimeters will be able to detect them only during elevated activity states, which could provide supportive evidence for the hadronic origin of the X-ray and γ-ray emission.
Why Are Some Gamma-Ray Bursts Hosted by Oxygen-rich Galaxies?
Authors: Hashimoto Tetsuya , Chaudhary Ravi , Ohta Kouji , Goto Tomotsugu , Hammer Francois , Kong Albert K. H. , Nomoto Ken’ichi , Mao Jirong
Published: August 2018

Theoretically long gamma-ray bursts (GRBs) are expected to happen in low-metallicity environments, because in a single massive star scenario, low iron abundance prevents loss of angular momentum through stellar wind, resulting in ultra-relativistic jets and the burst. In this sense, not just a simple metallicity measurement but also low iron abundance ([Fe/H] ≲ −1.0) is essentially important. Observationally, however, oxygen abundance has been measured more often due to stronger emission. In terms of oxygen abundance, some GRBs have been reported to be hosted by high-metallicity star-forming galaxies, in tension with theoretical predictions. Here we compare iron and oxygen abundances for the first time for GRB host galaxies (GRB 980425 and 080517) based on the emission-line diagnostics. The estimated total iron abundances, including iron in both gas and dust, are well below the solar value. The total iron abundances can be explained by the typical value of theoretical predictions ([Fe/H] ≲ −1.0), despite high oxygen abundance in one of them. According to our iron abundance measurements, the single massive star scenario still survives even if the oxygen abundance of the host is very high, such as the solar value. Relying only on oxygen abundance could mislead us on the origin of the GRBs. The measured oxygen-to-iron ratios, [O/Fe], can be comparable to the highest values among the iron-measured galaxies in the Sloan Digital Sky Survey. Possible theoretical explanations of such high [O/Fe] include the young age of the hosts, top-heavy initial mass function, and fallback mechanism of the iron element in supernova explosions.
SDSS-IV MaNGA: The Intrinsic Shape of Slow Rotator Early-type Galaxies
Authors: Li 李弘 Hongyu 宇 , Mao Shude , Cappellari Michele , Graham Mark T. , Emsellem Eric , Long R. J.
Published: August 2018

By inverting the distributions of galaxies’ apparent ellipticities and misalignment angles (measured around the projected half-light radius R
e) between their photometric and kinematic axes, we study the intrinsic shape distribution of 189 slow rotator early-type galaxies with stellar masses 2 × 1011
M
⊙ < M
* < 2 × 1012
M
⊙, extracted from a sample of about 2200 galaxies with integral-field stellar kinematics from the data release 14 (DR14) of the fourth-generation Sloan Digital Sky Survey IV (SDSS-IV) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) integral field unit (IFU) survey. Thanks to the large sample of slow rotators, Graham et al. showed that there is clear structure in the misalignment angle distribution, with two peaks at both 0° and 90° misalignment (characteristic of oblate and prolate rotation, respectively). Here we invert the observed distribution from Graham et al. The large sample allows us to go beyond the known fact that slow rotators are weakly triaxial and to place useful constraints on their intrinsic triaxiality distribution (around 1 R
e) for the first time. The shape inversion is generally non-unique. However, we find that, for a wide set of model assumptions, the observed distribution clearly requires a dominant triaxial-oblate population. For some of our models, the data suggest a minor triaxial-prolate population, but a dominant prolate population is ruled out.
Californium-254 and Kilonova Light Curves
Authors: Zhu Y. , Wollaeger R. T. , Vassh N. , Surman R. , Sprouse T. M. , Mumpower M. R. , Möller P. , McLaughlin G. C. , Korobkin O. , Kawano T. , Jaffke P. J. , Holmbeck E. M. , Fryer C. L. , Even W. P. , Couture A. J. , Barnes J.
Published: August 2018

Neutron star mergers offer unique conditions for the creation of the heavy elements, and additionally provide a testbed for our understanding of this synthesis known as the r-process. We have performed dynamical nucleosynthesis calculations and identified a single isotope, 254Cf, which has a particularly high impact on the brightness of electromagnetic transients associated with mergers on the order of 15 to 250 days. This is due to the anomalously long half-life of this isotope and the efficiency of fission thermalization compared to other nuclear channels. We estimate the fission fragment yield of this nucleus and outline the astrophysical conditions under which 254Cf has the greatest impact to the light curve. Future observations in the mid-infrared, which are bright during this regime, could indicate the production of actinide nucleosynthesis.
A Decline in the X-Ray through Radio Emission from GW170817 Continues to Support an Off-axis Structured Jet
Authors: Alexander K. D. , Margutti R. , Blanchard P. K. , Fong W. , Berger E. , Hajela A. , Eftekhari T. , Chornock R. , Cowperthwaite P. S. , Giannios D. , Guidorzi C. , Kathirgamaraju A. , MacFadyen A. , Metzger B. D. , Nicholl M. , Sironi L. , Villar V. A. , Williams P. K. G. , Xie X. , Zrake J.
Published: August 2018

We present new observations of the binary neutron star merger GW170817 at Δt ≈ 220–290 days post-merger, at radio (Karl G. Jansky Very Large Array; VLA), X-ray (Chandra X-ray Observatory), and optical (Hubble Space Telescope; HST) wavelengths. These observations provide the first evidence for a turnover in the X-ray light curve, mirroring a decline in the radio emission at ≳5σ significance. The radio-to-X-ray spectral energy distribution exhibits no evolution into the declining phase. Our full multi-wavelength data set is consistent with the predicted behavior of our previously published models of a successful structured jet expanding into a low-density circumbinary medium, but pure cocoon models with a choked jet cannot be ruled out. If future observations continue to track our predictions, we expect that the radio and X-ray emission will remain detectable until ∼1000 days post-merger.
Scolarisation des enfants de demandeurs d’asile : nouvelles pratiques, nouveaux dispositifs, nouveaux « métiers » sous le signe de l’incertitude
Authors: Sanchez-Mazas Margarita , Changkakoti Nilima , Mottet Geneviève
Published: August 2018

Cet article entend illustrer comment la question de la scolarisation des enfants de demandeurs d’asile en Suisse, en tension entre une politique d’asile restrictive et un assouplissement en matière d’accès à l’éducation, met à l’épreuve l’institution scolaire et suscite l’engagement d’une pluralité d’acteurs, que ce soit au niveau de l’implication des professionnel-le-s en place, ou au niveau des initiatives prises par des intervenants extérieurs. À partir d’entretiens semi-directifs avec différents acteurs de l’école, responsables des questions migratoires, directeurs/directrices d’établissement, enseignants ordinaires ou spécialisés dans l’accueil, éducateurs/éducatrices et intervenants sociaux, travailleurs bénévoles ou représentants du monde associatif, nous documentons les solutions ad hoc, les bricolages et les pistes d’action mis en œuvre en réponse à l’accueil et l’accompagnement des enfants de demandeurs d’asile et qui signalent, souvent de manière dramatique, l’irruption de la question sociale à l’école.
Team Reasoning and Spontaneous Collective Intentions
Authors: Gold Natalie
Published: August 2018

J’explore la tension apparente entre l’idée que les intentions collectives sont le résultat du raisonnement en équipe, et l’idée qu’il puisse exister des intentions collectives spontanées. Ce problème soulève une question plus générale quant au lien entre raisonnement et intentions spontanées, y compris dans le cas des intentions individuelles. Je montre que cette tension n’a pas lieu d’être lorsque la distinction est faite entre intentions et intentionnalité, car il devient possible de rejeter l’existence d’intentions spontanées, tout en conservant l’existence d’une intentionnalité spontanée, et ce dans les cas individuels et collectifs. Néanmoins, dans la mesure où le raisonnement individuel est un cas particulier du modèle de raisonnement en équipe, et que l’existence d’intentions individuelles spontanées est plausible, il semble souhaitable que les théoriciens du raisonnement en équipe soit également en mesure d’expliquer les intentions spontanées dans le cas collectif. Ceci nécessite de montrer que les intentions spontanées peuvent être compatibles avec le raisonnement. J’examine les différentes interprétations de l’idée de « raisonnement » en philosophie, économie, et science cognitive, et montre comment les intentions collectives spontanées peuvent être réconciliées avec certaines de ces interprétations, interprétations qui sont compatibles avec la manière dont le raisonnement est appréhendé dans la littérature sur le raisonnement en équipe. Je propose de comprendre le raisonnement en équipe comme un « modèle computationnel », tel qu’utilisé en science cognitive, et montre à partir de certaines théories en philosophie de la computation que cette approche présente des implications favorables aux théories d’agentivité collective, car elle permettrait que les groupes puissent être des raisonneurs.
The Efficiency of Team Reasoning
Authors: Paternotte Cédric
Published: August 2018

Le raisonnement en équipe est-il plus efficace que le raisonnement individuel ? Il devrait l’être, puisqu’il mène par définition des individus à adopter des stratégies collectivement optimales. De fait, on a pu lire que le raisonnement en équipe est plus rationnellement efficace et qu’il peut être plus viable du point de vue évolutionnaire que le raisonnement individuel. Cet article donne des raisons qui limitent ces deux affirmations, qui reposent sur une sous-estimation de l’efficacité du raisonnement individuel et sur une surestimation du pouvoir de coordination du raisonnement en équipe. Après ces rectificatifs, l’efficacité du raisonnement en équipe se révèle équivoque. D’un point de vue rationnel, l’efficacité supérieure du raisonnement par équipe dépend de conditions spécifiques concernant la nature du contexte d’interaction et la probabilité générale que des individus raisonnent en équipe. D’un point du vue évolutionnaire, l’apparition comme la stabilisation du raisonnement en équipe deviennent difficilement explicables.