bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing Cropland Area in West Africa for Agricultural Yield Analysis
Authors: Samasse Kaboro , Hanan Niall , Tappan Gray , Diallo Yacouba
Published: November 2018

Accurate estimates of cultivated area and crop yield are critical to our understanding of agricultural production and food security, particularly for semi-arid regions like the Sahel of West Africa, where crop production is mainly rain-fed and food security is closely correlated with the inter-annual variations in rainfall. Several global and regional land cover products, based on satellite remotely-sensed data, provide estimates of the agricultural land use intensity, but the initial comparisons indicate considerable differences among them, relating to differences in the satellite data quality, classification approaches, and spatial and temporal resolutions. Here, we quantify the accuracy of available cropland products across Sahelian West Africa using an independent, high-resolution, visually interpreted sample dataset that classifies all points across West Africa using a 2-km sample grid (~500,000 points for the study area). We estimate the “quantity” and “allocation” disagreements for the cropland class of eight land cover products in five Western Sahel countries (Burkina Faso, Mali, Mauritania, Niger, and Senegal). The results confirm that coarse spatial resolution (300 m, 500 m, and 1000 m) land cover products have higher disagreements in mapping the fragmented agricultural landscape of the Western Sahel. Earlier products (e.g., GLC2000) are less accurate than recent products (e.g., ESA CCI 2013, MODIS 2013 and GlobCover 2009). We also show that two of the finer spatial resolution maps (GFSAD30, and GlobeLand30) using advanced classification approaches (random forest, decision trees, and pixel-object combined) are currently the best available products for cropland identification. However, none of the eight land cover databases examined is consistent in reaching the targeted 75% accuracy threshold in the five Sahelian countries. The majority of currently available land cover products overestimate cultivated areas by an average of 170% relative to the cropland area in the reference data.
m-Polar Fuzzy Soft Weighted Aggregation Operators and Their Applications in Group Decision-Making
Authors: Zahedi Khameneh Azadeh , Kiliçman Adem
Published: November 2018

Aggregation operators are important tools for solving multi-attribute group decision-making (MAGDM) problems. The main challenging issue for aggregating data in a MAGDM problem is how to develop a symmetric aggregation operator expressing the decision makers’ behavior. In the literature, there are some methods dealing with this difficulty; however, they lack an effective approach for multi-polar inputs. In this study, a new aggregation operator for m-polar fuzzy soft sets (M-pFSMWM) reflecting different agreement scenarios within a group is presented to proceed MAGDM problems in which both attributes and experts have different weights. Moreover, some desirable properties of M-pFSMWM operator, such as idempotency, monotonicity, and commutativity (symmetric), that means being invariant under any permutation of the input arguments, are studied. Further, m-polar fuzzy soft induced ordered weighted average (M-pFSIOWA) operator and m-polar fuzzy soft induced ordered weighted geometric (M-pFSIOWG) operator, which are extensions of IOWA and IOWG operators, respectively, are developed. Two algorithms are also designed based on the proposed operators to find the final solution in MAGDM problems with weighted multi-polar fuzzy soft information. Finally, the efficiency of the proposed methods is illustrated by some numerical examples. The characteristic comparison of the proposed aggregation operators shows the M-pFSMWM operator is more adaptable for solving MAGDM problems in which different cases of agreement affect the final outcome.
A Novel Vertical Fragmentation Method for Privacy Protection Based on Entropy Minimization in a Relational Database
Authors: Hong Tie , Mei SongZhu , Wang ZhiYing , Ren JiangChun
Published: November 2018

Many scholars have attempted to use an encryption method to resolve the problem of data leakage in data outsourcing storage. However, encryption methods reduce data availability and are inefficient. Vertical fragmentation perfectly solves this problem. It was first used to improve the access performance of the relational database, and nowadays some researchers employ it for privacy protection. However, there are some problems that remain to be solved with the vertical fragmentation method for privacy protection in the relational database. First, current vertical fragmentation methods for privacy protection require the user to manually define privacy constraints, which is difficult to achieve in practice. Second, there are many vertical fragmentation solutions that can meet privacy constraints; however, there are currently no quantitative evaluation criteria evaluating how effectively solutions can protect privacy more effectively. In this article, we introduce the concept of information entropy to quantify privacy in vertical fragmentation, so we can automatically discover privacy constraints. Based on this, we propose a privacy protection model with a minimum entropy fragmentation algorithm to achieve minimal privacy disclosure of vertical fragmentation. Experimental results show that our method is suitable for privacy protection with a lower overhead.
Energy-Harvesting Powered Variable Storage Topology for Battery-Free Wireless Sensors
Authors: El Mahboubi Firdaous , Bafleur Marise , Boitier Vincent , Dilhac Jean-Marie
Published: November 2018

The energy autonomy of wireless sensors is one of the main roadblocks to their wide deployment. The purpose of this study is to propose simple adaptive storage architecture, which combined with energy harvesting, could replace a battery. The main concept is based on using several ultracapacitors (at least two) that are reconfigured in a series or in parallel according to its state of charge/discharge, either to speed up the startup of the powered system or to provide energy autonomy. The proposed structure is based on two ultra-capacitors, one of small capacitance value and one of big value. Powered by an energy-harvesting source, the devised control circuitry allows cold start up with empty ultra-capacitors, pre-regulated output voltage, and energy usage efficiency close to 94.7%.
Impact of Maternal Air Pollution Exposure on Children’s Lung Health: An Indian Perspective
Authors: Saha Pritam , Johny Ebin , Dangi Ashish , Shinde Sopan , Brake Samuel , Eapen Mathew Suji , Sohal Sukhwinder Singh , Naidu VGM , Sharma Pawan
Published: November 2018

Air pollution has become an emerging invisible killer in recent years and is a major cause of morbidity and mortality globally. More than 90% of the world’s children breathe toxic air every day. India is among the top ten most highly polluted countries with an average PM10 level of 134 μg/m3 per year. It is reported that 99% of India’s population encounters air pollution levels that exceed the World Health Organization Air Quality Guideline, advising a PM2.5 permissible level of 10 μg/m3. Maternal exposure to air pollution has serious health outcomes in offspring because it can affect embryonic phases of development during the gestation period. A fetus is more prone to effects from air pollution during embryonic developmental phases due to resulting oxidative stress as antioxidant mechanisms are lacking at that stage. Any injury during this vulnerable period (embryonic phase) will have a long-term impact on offspring health, both early and later in life. Epidemiological studies have revealed that maternal exposure to air pollution increases the risk of development of airway disease in the offspring due to impaired lung development in utero. In this review, we discuss cellular mechanisms involved in maternal exposure to air pollution and how it can impact airway disease development in offspring. A better understanding of these mechanisms in the context of maternal exposure to air pollution can offer a new avenue to prevent the development of airway disease in offspring.
Integrated Management of Skin NTDs—Lessons Learned from Existing Practice and Field Research
Authors: Yotsu Rie R.
Published: November 2018

Integration of neglected tropical diseases (NTDs) into the public health agenda has been a priority in global health for the last decade. Because a number of these diseases share not only the geographical distribution, but also a common feature which is skin involvement, bringing together a sub-group of ‘skin NTDs’ is one way forward to promote further integration among NTDs. With these diseases, which include leprosy, Buruli ulcer, yaws, mycetoma, lymphatic filariasis, and leishmaniasis, patients may be left with life-long deformities and disabilities when diagnosis and treatment are delayed. Stigma is another serious consequence of skin NTDs as it places a large barrier on the economic activities and social life of a patient. As a result, this creates a vicious cycle and obstructs a key goal of society, the elimination of poverty. Enhancement in surveillance systems as well as the further development of diagnostic methods, improvement in treatment and management, and identification of preventative measures for skin NTDs are therefore urgently needed. This article summarizes the existing practices and field research on skin NTDs and identifies potential synergies that could be achieved by adopting this integrated approach.
Unlocking the Potential of 46 New Bacteriophages for Biocontrol of Dickeya Solani
Authors: Carstens Alexander B. , Djurhuus Amaru M. , Kot Witold , Jacobs-Sera Deborah , Hatfull Graham F. , Hansen Lars H.
Published: November 2018

Modern agriculture is expected to face an increasing global demand for food while also needing to comply with higher sustainability standards. Therefore, control of crop pathogens requires new, green alternatives to current methods. Potatoes are susceptible to several bacterial diseases, with infections by soft rot Enterobacteriaceae (SRE) being a significant contributor to the major annual losses. As there are currently no efficient ways of combating SRE, we sought to develop an approach that could easily be incorporated into the potato production pipeline. To this end, 46 phages infecting the emerging potato pathogen Dickeya solani were isolated and thoroughly characterized. The 46 isolated phages were grouped into three different groups based on DNA similarity, representing two distinct clusters and a singleton. One cluster showed similarity to phages previously used to successfully treat soft rot in potatoes, whereas the remaining phages were novel and showed only very limited similarity to previously isolated phages. We selected six diverse phages in order to create the hereto most complex phage cocktail against SRE. The cocktail was applied in a proof-of-principle experiment to treat soft rot in potatoes under simulated storage conditions. We show that the phage cocktail was able to significantly reduce the incidence of soft rot as well as disease severity after 5 days of storage post-infection with Dickeya solani. This confirms results from previous studies that phages represent promising biocontrol agents against SRE infection in potato.
Antibiotic Therapy Using Phage Depolymerases: Robustness Across a Range of Conditions
Authors: Lin Han , Paff Matthew L. , Molineux Ian J. , Bull James J.
Published: November 2018

Phage-derived depolymerases directed against bacterial capsules are showing therapeutic promise in various animal models of infection. However, individual animal model studies are often constrained by use of highly specific protocols, such that results may not generalize to even slight modifications. Here we explore the robustness of depolymerase therapies shown to succeed in a previous study of mice. Treatment success rates were reduced by treatment delay, more so for some enzymes than others: K1- and K5 capsule-degrading enzymes retained partial efficacy on delay, while K30 depolymerase did not. Phage were superior to enzymes under delayed treatment only for K1. Route of administration (intramuscular versus intraperitoneal) mattered for success of K1E, possibly for K1F, not for K1H depolymerase. Significantly, K1 capsule-degrading enzymes proved highly successful when using immune-suppressed, leukopenic mice, even with delayed treatment. Evolution of bacteria resistant to K1-degrading enzymes did not thwart therapeutic success in leukopenic mice, likely because resistant bacteria were avirulent. In combination with previous studies these results continue to support the efficacy of depolymerases as antibacterial agents in vivo, but system-specific details are becoming evident.
Causes and Consequences of Spatial Within-Host Viral Spread
Authors: Gallagher Molly E. , Brooke Christopher B. , Ke Ruian , Koelle Katia
Published: November 2018

The spread of viral pathogens both between and within hosts is inherently a spatial process. While the spatial aspects of viral spread at the epidemiological level have been increasingly well characterized, the spatial aspects of viral spread within infected hosts are still understudied. Here, with a focus on influenza A viruses (IAVs), we first review experimental studies that have shed light on the mechanisms and spatial dynamics of viral spread within hosts. These studies provide strong empirical evidence for highly localized IAV spread within hosts. Since mathematical and computational within-host models have been increasingly used to gain a quantitative understanding of observed viral dynamic patterns, we then review the (relatively few) computational modeling studies that have shed light on possible factors that structure the dynamics of spatial within-host IAV spread. These factors include the dispersal distance of virions, the localization of the immune response, and heterogeneity in host cell phenotypes across the respiratory tract. While informative, we find in these studies a striking absence of theoretical expectations of how spatial dynamics may impact the dynamics of viral populations. To mitigate this, we turn to the extensive ecological and evolutionary literature on range expansions to provide informed theoretical expectations. We find that factors such as the type of density dependence, the frequency of long-distance dispersal, specific life history characteristics, and the extent of spatial heterogeneity are critical factors affecting the speed of population spread and the genetic composition of spatially expanding populations. For each factor that we identified in the theoretical literature, we draw parallels to its analog in viral populations. We end by discussing current knowledge gaps related to the spatial component of within-host IAV spread and the potential for within-host spatial considerations to inform the development of disease control strategies.
Detection of a Conspecific Mycovirus in Two Closely Related Native and Introduced Fungal Hosts and Evidence for Interspecific Virus Transmission
Authors: Schoebel Corine N. , Prospero Simone , Gross Andrin , Rigling Daniel
Published: November 2018

Hymenoscyphus albidus is a native fungus in Europe where it behaves as a harmless decomposer of leaves of common ash. Its close relative Hymenoscyphus fraxineus was introduced into Europe from Asia and currently threatens ash (Fraxinus sp.) stands all across the continent causing ash dieback. H. fraxineus isolates from Europe were previously shown to harbor a mycovirus named Hymenoscyphus fraxineus Mitovirus 1 (HfMV1). In the present study, we describe a conspecific mycovirus that we detected in H. albidus. HfMV1 was consistently identified in H. albidus isolates (mean prevalence: 49.3%) which were collected in the sampling areas before the arrival of ash dieback. HfMV1 strains in both fungal hosts contain a single ORF of identical length (717 AA) for which a mean pairwise identity of 94.5% was revealed. The occurrence of a conspecific mitovirus in H. albidus and H. fraxineus is most likely the result of parallel virus evolution in the two fungal hosts. HfMV1 sequences from H. albidus showed a higher nucleotide diversity and a higher number of mutations compared to those from H. fraxineus, probably due to a bottleneck caused by the introduction of H. fraxineus in Europe. Our data also points to multiple interspecific virus transfers from H. albidus to H. fraxineus, which could have contributed to the intraspecific virus diversity found in H. fraxineus.
Spatiotemporal Variations in Mercury Bioaccumulation at Fine and Broad Scales for Two Freshwater Sport Fishes
Authors: Thomas Shyam M. , Melles Stephanie J. , Bhavsar Satyendra P.
Published: November 2018

Bioaccumulation of mercury in sport fish is a complex process that varies in space and time. Both large-scale climatic as well as fine-scale environmental factors are drivers of these space-time variations. In this study, we avail a long-running monitoring program from Ontario, Canada to better understand spatiotemporal variations in fish mercury bioaccumulation at two distinct scales. Focusing on two common large-bodied sport fishes (Walleye and Northern Pike), the data were analyzed at fine- and broad-scales, where fine-scale implies variations in bioaccumulation at waterbody- and year-level and broad-scale captures variations across 3 latitudinal zones (~5° each) and eight time periods (~5-year each). A series of linear mixed-effects models (LMEMs) were employed to capture the spatial, temporal and spatiotemporal variations in mercury bioaccumulation. Fine-scale models were overall better fit than broad-scale models suggesting environmental factors operating at the waterbody-level and annual climatic conditions matter most. Moreover, for both scales, the space time interaction explained most of the variation. The random slopes from the best-fitting broad-scale model were used to define a bioaccumulation index that captures trends within a climate change context. The broad-scale trends suggests of multiple and potentially conflicting climate-driven mechanisms. Interestingly, broad-scale temporal trends showed contrasting bioaccumulation patterns—increasing in Northern Pike and decreasing in Walleye, thus suggesting species-specific ecological differences also matter. Overall, by taking a scale-specific approach, the study highlights the overwhelming influence of fine-scale variations and their interactions on mercury bioaccumulation; while at broad-scale the mercury bioaccumulation trends are summarized within a climate change context.
Quantifying Urban Bioswale Nitrogen Cycling in the Soil, Gas, and Plant Phases
Authors: Shetty Nandan , Hu Ranran , Hoch Jessica , Mailloux Brian , Palmer Matthew , Menge Duncan N. L. , McGuire Krista , McGillis Wade , Culligan Patricia
Published: November 2018

Bioswales are a common feature of urban green infrastructure plans for stormwater management. Despite this fact, the nitrogen (N) cycle in bioswales remains poorly quantified, especially during dry weather in the soil, gas, and plant phases. To quantify the nitrogen cycle across seven bioswale sites located in the Bronx, New York City, we measured rates of ammonium and nitrate production in bioswale soils. We also measured soil nitrous oxide gas emissions and plant foliar nitrogen. We found that all mineralized nitrogen underwent nitrification, indicating that the soils were nitrogen-rich, particularly during summer months when nitrogen cycling rates increase, as indicated by higher levels of ammonium in the soil. In comparison to mineralization (0 to 110 g N m−2 y−1), the amounts of nitrogen uptake by the plants (0 to 5 g N m−2 y−1) and of nitrogen in gas emissions from the soils (1 to 10 g N m−2 y−1) were low, although nitrous oxide gas emissions increased in the summer. The bioswales’ greatest influx of nitrogen was via stormwater (84 to 591 g N m−2 y−1). These findings indicate that bioswale plants receive overabundant nitrogen from stormwater runoff. However, soils currently used for bioswales contain organic matter contributing to the urban nitrogen load. Thus, bioswale designs should use less nitrogen rich soils and minimize fertilization for lower nitrogen runoff.
Seasonal Variations in Water Uptake Patterns of Winter Wheat under Different Irrigation and Fertilization Treatments
Authors: Ma Ying , Song Xianfang
Published: November 2018

Irrigation and fertilization both affect the water cycle in agricultural ecosystems. It is difficult to quantify root water uptake (RWU) which varies with crop development and seasons. In this study, a Bayesian mixing model (MixSIAR) coupling with dual stable isotopes (D and 18O) was used to quantify RWU patterns for winter wheat under different irrigation and fertilization treatments between 2014 and 2015 in Beijing, China. The main RWU depth during the greening-jointing, jointing-heading, heading-filling, and filling-harvest stages was 0–20 cm, 20–70 cm, 0–20 cm, and 20–70 cm, respectively, which showed water uptake proportions of 67.0%, 42.0%, 38.7%, and 34.9%, respectively. Significant differences in RWU patterns appeared between the 2014 and 2015 seasons. The main RWU depth increased gradually from 0–20 cm at the greening-jointing stage to 20–70 cm at the jointing-heading stage and 70–150 cm during the heading to harvest period in 2014. However, winter wheat primarily took up soil water from the 0–70 cm layer in 2015. The average water uptake proportion in the top layer (0–20 cm) in 2015 (42.6%) was remarkably higher than that in 2014 (28.7%). There was a significantly negative relationship (p < 0.01) between the water uptake proportion and the proportion of root length at the filling-harvest stage in 2014, while no significant correlation (p > 0.05) was found in 2015. Variable distributions of root characteristics and soil moisture induced by different irrigation and fertilization comprehensively affected the RWU profile, particularly under severe drought environments in 2015. Treatments with fertilization of 105 kg hm−2 N or irrigation of 20 mm during the greening-jointing stage significantly promoted water uptake contribution in the 70–150 cm (32.2%) and 150–200 cm (23.5%) layers at the jointing-heading stage in 2015, while other treatments had a shallow dominant RWU depth (0–20 cm). The planned wetting layer should be kept within the main RWU depth of 0–70 cm for improving irrigation water use efficiency.
Experimental Study of Overland Flow through Rigid Emergent Vegetation with Different Densities and Location Arrangements
Authors: Wang Yuting , Zhang Huilan , Yang Pingping , Wang Yunqi
Published: November 2018

The effect of vegetation density on overland flow dynamics has been extensively studied, yet fewer investigations have focused on vegetation arrangements with different densities and position features. Flume experiments were conducted to investigate the hydrodynamics of flow through rigid emergent vegetation arranged in combinations with three densities (Dense, Middle, and Sparse) and three positions (summit, backslope, and footslope). This study focused on how spatial variations regulated hydrodynamic parameters from two dimensions: direction along the slope and water depth. The total hydrodynamic parameters of bare slopes were significantly different from those of vegetated slopes. The relationship between Re and f illustrated that Re was not a unique predictor of hydraulic roughness on vegetated slopes. In the slope direction, all hydrodynamic parameters on vegetated slopes exhibited fluctuating downward/upward trends due to the clocking effect before the vegetated area and the rapid conveyance effect in the vegetated area, whereas constant values were observed on bare slopes. The performance of hydrodynamics parameters suggested that the dense rearward arrangement (SMD) was the optimal vegetation pattern to regulate flow conditions. Specifically, the vertical profiles of the velocity and turbulence features of the SMD arrangement at different sections demonstrated the significant role of vegetation density in identifying the velocity layers along the water depth. The maximum velocity and Reynolds Stress Number (RSN) indicated the position where local scour was most likely to occur, which would improve our basic understanding of the mechanisms underlying hydraulic and soil erosion processes.
Organic Amendments Influence Soil Water Depletion, Root Distribution, and Water Productivity of Summer Maize in the Guanzhong Plain of Northwest China
Authors: Zhao Li-Li , Li Lu-Sheng , Cai Huan-Jie , Shi Xiao-Hu , Zhang Chao
Published: November 2018

Organic amendments improve general soil conditions and stabilize crop production, but their effects on the soil hydrothermal regime, root distribution, and their contributions to water productivity (WP) of maize have not been fully studied. A two-year field experiment was conducted to investigate the impacts of organic amendments on soil temperature, water storage depletion (SWSD), root distribution, grain yield, and the WP of summer maize (Zea mays L.) in the Guanzhong Plain of Northwest China. The control treatment (CO) applied mineral fertilizer without amendments, and the three amended treatments applied mineral fertilizer with 20 Mg ha−1 of wheat straw (MWS), farmyard manure (MFM), and bioorganic fertilizer (MBF), respectively. Organic amendments decreased SWSD compared to CO, and the lowest value was obtained in MBF, followed by MWS and MFM. Meanwhile, the lowest mean topsoil (0–10 cm) temperature was registered in MWS. Compared to CO, organic amendments generally improved the root length density (RLD) and root weight density (RWD) of maize. MBF showed the highest RLD across the whole soil profile, while MWS yielded the greatest RWD to 20 cm soil depth. Consequently, organic amendments increased grain yield by 9.9–40.3% and WP by 8.6–47.1% compared to CO, and the best performance was attained in MWS and MBF. We suggest that MWS and MBF can benefit the maize agriculture in semi-arid regions for higher yield, and WP through regulating soil hydrothermal conditions and improving root growth.
Enhanced Phosphate Removal from Water by Honeycomb-Like Microporous Lanthanum-Chitosan Magnetic Spheres
Authors: Cheng Rong , Shen Liang-Jie , Zhang Ying-Ying , Dai Dan-Yang , Zheng Xiang , Liao Long-Wen , Wang Lei , Shi Lei
Published: November 2018

The removal of phosphate in water is crucial and effective for control of eutrophication, and adsorption is one of the most effective treatment processes. In this study, microporous lanthanum-chitosan magnetic spheres were successfully synthetized and used for the removal of phosphate in water. The characterization results show that the dispersion of lanthanum oxide is improved because of the porous properties of the magnetic spheres. Moreover, the contact area and active sites between lanthanum oxide and phosphate were increased due to the presence of many honeycomb channels inside the magnetic spheres. In addition, the maximum adsorption capacity of the Langmuir model was 27.78 mg P·g−1; and the adsorption kinetics were in good agreement with the pseudo-second-order kinetic equation and intra-particle diffusion model. From the results of thermodynamic analysis, the phosphate adsorption process of lanthanum-chitosan magnetic spheres was spontaneous and exothermic in nature. In conditional tests, the optimal ratio of lanthanum/chitosan was 1.0 mmol/g. The adsorption capacity of as-prepared materials increased with the augmentation of the dosage of the adsorbent and the decline of pH value. The co-existing anions, Cl− and NO3− had little effect on adsorption capacity to phosphate, while CO32− exhibited an obviously negative influence on the adsorption capacity of this adsorbent. In general, owing to their unique hierarchical porous structures, high-adsorption capacity and low cost, lanthanum-chitosan magnetic spheres are potentially applicable in eutrophic water treatment.
A New Well-Balanced Reconstruction Technique for the Numerical Simulation of Shallow Water Flows with Wet/Dry Fronts and Complex Topography
Authors: Zhu Zhengtao , Yang Zhonghua , Bai Fengpeng , An Ruidong
Published: November 2018

This study develops a new well-balanced scheme for the one-dimensional shallow water system over irregular bed topographies with wet/dry fronts, in a Godunov-type finite volume framework. A new reconstruction technique that includes flooded cells and partially flooded cells and preserves the non-negative values of water depth is proposed. For the wet cell, a modified revised surface gradient method is presented assuming that the bed topography is irregular in the cell. For the case that the cell is partially flooded, this paper proposes a special reconstruction of flow variables that assumes that the bottom function is linear in the cell. The Harten–Lax–van Leer approximate Riemann solver is applied to evaluate the flux at cell faces. The numerical results show good agreement with analytical solutions to a set of test cases and experimental results.
Sur la localisation des éléments en traces dans les minéraux et les roches
Authors: Goñi Juan C. , Guillemin Claude
Published: November 2018

Les auteurs ont étudié la localisation des éléments en traces à l'aide de la sonde électronique, et ont pu prouver que la surface intercristalline (film intergranulaire) est le siège d'une importante accumulation de ces éléments. Les phénomènes d'adsorption liés à ce film intergranulaire apparaissent comme de nouveaux facteurs de fixation, jouant un grand rôle dans la répartition géochimique des éléments. Dans cette communication préliminaire on présente quelques exemples de localisation d'éléments (Ni, Ce, La, Cu, Cr, V, As, W) dans certaines roches et silicates constitutifs de ces roches.
Croissance cristalline et répartition des oligo-éléments dans une pyrite triglyphe
Authors: Machairas Georges
Published: November 2018

L'étude d'un cristal de pyrite de type triglyphe a montré que la forme cubique était construite par une répétition d'un très grand nombre des formes hémiédriques. Les oligo-éléments Pb˗Co˗Ag˗Cu se trouvent concentrés plutôt à la périphérie que vers le centre du cristal.

Nous avons étudié un cristal de pyrite de forme cubique et de 6,5 cm d'arête, provenant de la mine Cassandra (Grèce). Ce cristal de pyrite a été coupé par des plans passant par sa partie centrale et il a été possible d'observer la croissance du cristal du centre vers la périphérie.
Structure and properties of silicate melts
Authors: Brückner Rolf
Published: November 2018

Après une brève revue de l'état vitreux, et de la structure des verres de silice et de silicates, on discute les propriétés des silicates fondus, en particulier les aspects structuraux qui ne peuvent pas être extrapolés ou déduits de mesures sur les silicates vitreux. On discute les sujets suivants : le comportement de fluage (newtonien, non-newtonien, viscoélastique), l'anisotropie et les phénomènes d'orientation, la fracture à haute température, et la séparation de phase. On discute les possibilités d'obtenir des informations sur les aspects structuraux des silicates liquides à partir de méthodes et traitements de bains fondus, sensibles à la structure.
Approche statistique de la structure des silicates fondus
Authors: Dron Roger
Published: November 2018

The tetrahedral units constituting the anionic network of silicate melts form a population containing five species the relative abundance of which depends on the degree of neutralization of the silica. These species may be enumerated by the probability calculation.

In the absence of an electrostatic repulsion effect, the species are distributed in accordance with a binomial law of the fourth degree, and the model may be applied regardless of the composition.

It is shown that Masson' s model, applicable to compositions that are more basic than the metasilicate, can be developed by a statistical approach provided that the first two species are excluded.

By analogy, the problem of compositions less basic than the metasilicate is solved by eliminating the last two species. In a similar manner, the problem of compositions close to the metasilicate is solved by eliminating the first and last species.

In these domains, the anionic network would seem to be formed of four-strand nodes (first species) or three-strand nodes (second species). The strands are formed of (SiO2-3), chains and may have free ends. They are distributed in function of «in a decreasing geometrical progression.

The mean length of the strands can be calculated, and is invariably of the order of only a few units.
The mixing properties of melts in the system NaAlSi2O6-KAlSi2O6 determined by Knudsen Cell Mass Spectrometry
Authors: Fraser Donald G. , Rammensee Werner , Jones Rhian H.
Published: November 2018

The activities of the NaAlSi2O6 and KAlSi2O6 components in melts in the pseudobinary system NaAlSi2O6-KAlSi2O6 have been determined from 1150-1530 °C by Knudsen Cell Mass Spectrometry. Mixing is close to ideal despite the dissimilar structures of crystalline NaAlSi2O6 and KAlSi2O6. This may reflect a re-organization of the melt in Na-rich compositions to give NaAlSiO4-like and SiO2 like constituents more similar to the cage structure of nepheline than that of the pyroxene chains in jadeite and with A1 in tetrahedral rather than octahedral co-ordination. The partial molar heats and excess entropies of mixing show a pronounced minimum at the composition Na/K = 3 :1 which compares closely with the composition of crystalline Na3K-nepheline. This may be an example of a more general phenomenon in which liquids tend to approximate the structure of the crystalline phase which is stable on the liquidus at the particular composition rather than that of a mineral having the same composition as the melt. This is likely to be an important consideration in considering theoretically the crystallization and melting of incongruently melting silicate minerals.
Etude thermodynamique du système albite-orthose par calorimétrie de dissolution et effusion de Knudsen couplée à un spectomètre de masse
Authors: Rogez Jacques , Chastel Raymond , Bergman Claire , Brousse Christian , Castanet Robert , Mathieu Jean-Claude
Published: November 2018

The enthalpy of mixing of the vitreous solution of albite and orthoclase were deduced from the thermal effects corresponding to the dissolution of albite, orthoclase and their mixtures in liquid lead metaborate at 970 K. The Gibbs energy of these mixtures was also determined by Knudsen-cell mass-spectrometry. The thermodynamic behavior of the system is characterized by weak negative departures from ideality.
Kinetics of sub-liquidus phase separation in silicate and borate glasses. A review
Authors: Craievich Aldo F. , Zanotto Edgar E , James Peter F.
Published: November 2018

Many silicate and borate glass systems exhibit sub-liquidus immiscibility. The fine-scale microstructure of phase separated systems has been studied mainly by electron microscopy and small angle X-ray scattering. The classical theories of homogeneous nucleation, spinodal decomposition and coarsening, and more recent statistical theories of segregation are outlined. These theories are compared with experimental data for the kinetics of amorphous phase separation. In the early stages of separation, for compositions and temperatures in the region between the binodal and spinodal and in particular close to the binodal, the results are consistent with a homogeneous nucleation process. The classical theory of spinodal decomposition only agrees qualitatively with experimental data for the central region of the miscibility gap. The kinetics of coarsening are in general agreement with theory. Recent predictions from computer simulation studies on model alloys appear to be valid for glass systems. Experimental studies of the influence of amorphous phase separation on crystallization of glasses are also reviewed. In certain circumstances there is clear evidence that amorphous phase separation enhances the rates of crystal nucleation and growth.
Melt-fluid interaction deduced from studies of silicate-B2O3-H2O systems at 1 kbar
Authors: Pichavant Michel
Published: November 2018

Le bore est un constituant supplémentaire important associé aux processus de cristallisation des magmas granitiques riches en silice. Une discussion théorique des relations de phase dans un système ternaire modèle est présentée. On donne les résultats expérimentaux obtenus à P = 1 kbar, T = 500 °C dans le système SiO2-B2O3-H2O et on les compare avec les relations de phase déterminées pour le système Qz -Ab -Or -B2O3 -H2O à la même pression. La réduction des températures de début de fusion pour les systèmes silicate-H2O et l'accroissement de la charge silicatée dissoute dans la phase vapeur sont considérés comme les effets les plus importants en pratique, suite à l'introduction du bore. Les facteurs qui gouvernent la coordination du bore (BIII et BIV) dans les magmas silicatés sont divers : composition en alcalins et aluminium, température, pression. Les données sont contradictoires quant à l'incorporation des unités structurales borées dans le réseau silicaté ou non (unités borées segrégées dans le bain fondu).
Liquides non newtoniens et ordre local
Authors: Quentrec Bernard
Published: November 2018

Dans un fluide dense les molécules sont organisées localement. Nous tenons compte de cette organisation pour généraliser l'hydrodynamique et proposer des équations applicables aux fluides non Newtoniens. A cet effet nous introduisons des paramètres d'ordre locaux et nous utilisons la thermodynamique hors d'équilibre. Lorsque les mouvements au sein du fluide sont petits, il est possible de linéariser les équations. Nous pouvons alors les résoudre exactement. Nous avons pu ainsi interpréter des expériences ultrasonores et de diffusion de la lumière dans des liquides très visqueux. Il est également possible de résoudre les équations pour un écoulement de Couette plan. On obtient alors une viscosité dépendant du taux de cisaillement en accord raisonnable avec des résultats expérimentaux.
Site-controlled formation of single Si nanocrystals in a buried SiO2 matrix using ion beam mixing
Authors: Xu Xiaomo , Prüfer Thomas , Wolf Daniel , Engelmann Hans-Jürgen , Bischoff Lothar , Hübner René , Heinig Karl-Heinz , Möller Wolfhard , Facsko Stefan , von Borany Johannes , Hlawacek Gregor
Published: November 2018

For future nanoelectronic devices – such as room-temperature single electron transistors – the site-controlled formation of single Si nanocrystals (NCs) is a crucial prerequisite. Here, we report an approach to fabricate single Si NCs via medium-energy Si+ or Ne+ ion beam mixing of Si into a buried SiO2 layer followed by thermally activated phase separation. Binary collision approximation and kinetic Monte Carlo methods are conducted to gain atomistic insight into the influence of relevant experimental parameters on the Si NC formation process. Energy-filtered transmission electron microscopy is performed to obtain quantitative values on the Si NC size and distribution in dependence of the layer stack geometry, ion fluence and thermal budget. Employing a focused Ne+ beam from a helium ion microscope, we demonstrate site-controlled self-assembly of single Si NCs. Line irradiation with a fluence of 3000 Ne+/nm2 and a line width of 4 nm leads to the formation of a chain of Si NCs, and a single NC with 2.2 nm diameter is subsequently isolated and visualized in a few nanometer thin lamella prepared by a focused ion beam (FIB). The Si NC is centered between the SiO2 layers and perpendicular to the incident Ne+ beam.
The Discourse Function of Left Dislocation in Czech
Authors: Sturgeon Anne
Published: November 2018

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A GROUP DECISION-MAKING MODEL FOR WASTEWATER TREATMENT PLANS SELECTION BASED ON INTUITIONISTIC FUZZY SETS
Authors: Zhou Zhexuan , Dou Yajie , Zhang Xiaoxiong , Zhao Danling , Tan Yuejin
Published: November 2018

As the need for environmental protection and resource sustainability has increased in recent times, wastewater treatment has become increasingly important. In this paper, a group decision-making model for plans selection in wastewater treatment is proposed. In order to deal with uncertainties and multiple attributes in wastewater treatment, an intuitionistic fuzzy set is employed to evaluate wastewater treatment plans effectively. A distance measure is defined to obtain an objective weight measuring the expert’s judgment. More specifically, experts first use group decision-making on the various plans with an intuitionistic fuzzy set. Meanwhile, Due to the decision-makers psychological behavior, the prospect theory is applied. Next, the various plans are ranked by The Order of Preference by Similarity to Ideal Solution (TOPSIS) method and prospect theory. Finally, an illustrative example of wastewater treatment plans selection is used to verify the proposed model.
Regimes of the Vishniac–Ryu Decelerating Shock Instability
Authors: Drake R. P. , Doss F. W.
Published: November 2018

Here we revisit the derivation of the instability of dense shocked layers, originally developed by Vishniac and Ryu. Our motivation is that density profiles found in actual astrophysical and laboratory systems often do not match the assumptions in that paper. In order to identify the anticipated theoretical growth rates for various circumstances, one must first revisit the derivation and allow for the possibility that the density scale length differs, in magnitude and/or in sign, from the isothermal scale height. This analysis leads us to find regimes of purely convective instability and also of Vishniac stabilization of this instability, in addition to some new regimes of Vishniac behavior. We also identify a typographical error in the original paper that matters for quantitative evaluation of growth rates.
Pre-merger Electromagnetic Counterparts of Binary Compact Stars
Authors: Wang Jie-Shuang , Peng Fang-Kun , Wu Kinwah , Dai Zi-Gao
Published: November 2018

We investigate emission signatures of binary compact star gravitational wave (GW) sources consisting of strongly magnetized neutron stars (NSs) and/or white dwarfs (WDs) in their late-time inspiral phase. Because of electromagnetic interactions between the magnetospheres of the two compact stars, a substantial amount of energy will be extracted, and the resultant power is expected to be ∼1038–1044 erg s−1 in the last few seconds before the two stars merge, when the binary system contains a NS with a surface magnetic field 1012 G. The induced electric field in the process can accelerate charged particles up to the EeV energy range. Synchrotron radiation is emitted from energetic electrons, with radiative energies reaching the GeV energy for binary NSs and the MeV energy for NS–WD or double WD binaries. In addition, a blackbody component is also presented, and it peaks at several to hundreds keV for binary NSs and at several keV for NS–WD or double WD binaries. The strong angular dependence of the synchrotron radiation and the isotropic nature of the blackbody radiation lead to distinguishable modulation patterns between the two emission components. If coherent curvature radiation is presented, fast radio bursts could be produced. These components provide unique simultaneous electromagnetic signatures as precursors of GW events associated with magnetized compact star mergers and short gamma-ray bursts (e.g., GRB 100717).
Three-dimensional Oscillations of 21 Halo Coronal Mass Ejections Using Multi-spacecraft Data
Authors: Lee Harim , Moon Y.-J. , Nakariakov V. M. , Na Hyeonock , Cho Il-Hyun , Park Eunsu
Published: November 2018

We investigate the 3D structure of kinematic oscillations of full halo coronal mass ejections (FHCMEs) using multi-spacecraft coronagraph data from two non-parallel lines of sight. For this, we consider 21 FHCMEs which are simultaneously observed by the Solar and Heliospheric Observatory and the Solar TErrestrial RElations Observatory A or B, from 2010 June to 2012 August when the spacecraft were roughly in quadrature. Using sequences of running difference images, we estimate the instantaneous projected speeds of the FHCMEs at 24 different azimuthal angles in the planes of the sky of those coronagraphs. We find that all these FHCMEs have experienced kinematic oscillations characterized by quasi-periodic variations of the instantaneous projected radial velocity with periods ranging from 24 to 48 min. The oscillations detected in the analyzed events are found to show distinct azimuthal wave modes. Thirteen events (about 62%) are found to oscillate with the azimuthal wave number m = 1. The oscillating directions of the nodes of the m = 1 mode for these FHCMEs are consistent with those of their position angles (or the direction of eruption), with a mean difference of about 23°. The oscillation amplitude is found to correlate well with the projected radial speed of the CME. An estimation of Lorentz accelerations shows that they are dominant over other forces, implying that the magnetic force is responsible for the kinematic oscillations of CMEs. However, we cannot rule out other possibilities: a global layer of enhanced current around the CMEs or the nonlinear nature of its driver, for example the effect of vortex shedding.
A Strong Jet Signature in the Late-time Light Curve of GW170817
Authors: Mooley K. P. , Frail D. A. , Dobie D. , Lenc E. , Corsi A. , De K. , Nayana A. J. , Makhathini S. , Heywood I. , Murphy T. , Kaplan D. L. , Chandra P. , Smirnov O. , Nakar E. , Hallinan G. , Camilo F. , Fender R. , Goedhart S. , Groot P. , Kasliwal M. M. , Kulkarni S. R. , Woudt P. A.
Published: November 2018

We present new 0.6–10 GHz observations of the binary neutron star merger GW170817 covering the period up to 300 days post-merger, taken with the upgraded Karl G. Jansky Very Large Array, the Australia Telescope Compact Array, the Giant Metrewave Radio Telescope and the MeerKAT telescope. We use these data to precisely characterize the decay phase of the late-time radio light curve. We find that the temporal decay is consistent with a power-law slope of t
−2.2, and that the transition between the power-law rise and decay is relatively sharp. Such a slope cannot be produced by a quasi-isotropic (cocoon-dominated) outflow, but is instead the classic signature of a relativistic jet. This provides strong observational evidence that GW170817 produced a successful jet, and directly demonstrates the link between binary neutron star mergers and short-hard gamma-ray bursts. Using simple analytical arguments, we derive constraints on the geometry and the jet opening angle of GW170817. These results are consistent with those from our companion very long baseline interferometry paper, reporting superluminal motion in GW170817.
Triptyque sur la comédie
Authors: Fiorentino Francesco , Pavesio Monica
Published: November 2018

Pour construire une bibliographie des études italiennes sur la comédie française du xvii e  siècle, nous avons partagé le théâtre comique en trois périodes : la comédie avant Molière, la comédie de Molière – à qui nous avons laissé la centralité qui lui revient – et la comédie des contemporains et des successeurs de Molière. En ce qui concerne la comédie avant Molière, les études des francisants italiens se sont concentrées sur la circulation des sujets espagnols et italiens en France, avec les travaux de Daniela Dalla Valle, Valeria Pompejano, Monica Pavesio, Alessandra Preda. On peut faire commencer la critique italienne sur l’œuvre de Molière par les études de Giovanni Macchia à propos des personnages de Dom Juan et de Tartuffe. La génération successive a fourni la contribution la plus importante avec l’interprétation que Francesco Orlando a donnée du Misanthrope. Plus récemment il faut signaler en particulier les travaux de Delia Gambelli sur les rapports de Molière avec la commedia dell’arte et ceux de Francesco Fiorentino sur la conception du ridicule et du comique dans ses comédies. Quant à la comédie des contemporains et des successeurs de Molière, la question de l’influence de la commedia dell’arte continue à se révéler centrale, par exemple avec l’édition de Dorimond, fournie par Mariangela Mazzocchi Doglio et les études de Claudio Vinti et Barbara Sommovigo.