bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of environmental factors on transmission rates of the COVID-19 outbreak: an initial assessment in two spatial scales
Authors: Poirier Canelle , Luo Wei , Majumder Maimuna S. , Liu Dianbo , Mandl Kenneth D. , Mooring Todd A. , Santillana Mauricio 
Published: October 2020

AbstractFirst identified in Wuhan, China, in December 2019, a novel coronavirus (SARS-CoV-2) has affected over 16,800,000 people worldwide as of July 29, 2020 and was declared a pandemic by the World Health Organization on March 11, 2020. Influenza studies have shown that influenza viruses survive longer on surfaces or in droplets in cold and dry air, thus increasing the likelihood of subsequent transmission. A similar hypothesis has been postulated for the transmission of COVID-19, the disease caused by SARS-CoV-2. It is important to propose methodologies to understand the effects of environmental factors on this ongoing outbreak to support decision-making pertaining to disease control. Here, we examine the spatial variability of the basic reproductive numbers of COVID-19 across provinces and cities in China and show that environmental variables alone cannot explain this variability. Our findings suggest that changes in weather (i.e., increase of temperature and humidity as spring and summer months arrive in the Northern Hemisphere) will not necessarily lead to declines in case counts without the implementation of drastic public health interventions.
Microbial communities associated with the camel tick, Hyalomma dromedarii: 16S rRNA gene-based analysis
Authors: Perveen Nighat , Muzaffar Sabir Bin , Vijayan Ranjit , Al-Deeb Mohammad Ali 
Published: October 2020

AbstractHyalomma dromedarii is an important blood-feeding ectoparasite that affects the health of camels. We assessed the profile of bacterial communities associated with H. dromedarii collected from camels in the eastern part of the UAE in 2010 and 2019. A total of 100 partially engorged female ticks were taken from tick samples collected from camels (n = 100; 50/year) and subjected to DNA extraction and sequencing. The 16S rRNA gene was amplified from genomic DNA and sequenced using Illumina MiSeq platform to elucidate the bacterial communities. Principle Coordinates Analysis (PCoA) was conducted to determine patterns of diversity in bacterial communities. In 2010 and 2019, we obtained 899,574 and 781,452 read counts and these formed 371 and 191 operational taxonomic units (OTUs, clustered at 97% similarity), respectively. In both years, twenty-five bacterial families with high relative abundance were detected and the following were the most common: Moraxellaceae, Enterobacteriaceae, Staphylococcaceae, Bacillaceae, Corynebacteriaceae, Flavobacteriaceae, Francisellaceae, Muribaculaceae, Neisseriaceae, and Pseudomonadaceae. Francisellaceae and Enterobacteriaceae coexist in H. dromedarii and we suggest that they thrive under similar conditions and microbial interactions inside the host. Comparisons of diversity indicated that microbial communities differed in terms of richness and evenness between 2010 and 2019, with higher richness but lower evenness in communities in 2010. Principle coordinates analyses showed clear clusters separating microbial communities in 2010 and 2019. The differences in communities suggested that the repertoire of microbial communities have shifted. In particular, the significant increase in dominance of Francisella and the presence of bacterial families containing pathogenic genera shows that H. dromedarii poses a serious health risk to camels and people who interact with them. Thus, it may be wise to introduce active surveillance of key genera that constitute a health hazard in the livestock industry to protect livestock and people.
A scoping review on incentives for adoption of sustainable agricultural practices and their outcomes
Authors: Piñeiro Valeria , Arias Joaquín , Dürr Jochen , Elverdin Pablo , Ibáñez Ana María , Kinengyere Alison , Opazo Cristian Morales , Owoo Nkechi , Page Jessica R. , Prager Steven D. , Torero Maximo 
Published: October 2020

AbstractThe increasing pressure on agricultural production systems to achieve global food security and prevent environmental degradation necessitates a transition towards more sustainable practices. The purpose of this scoping review is to understand how the incentives offered to farmers motivate the adoption of sustainable agricultural practices and, ultimately, how and whether they result in measurable outcomes. To this end, this scoping review examines the evidence of nearly 18,000 papers on whether incentive-based programmes lead to the adoption of sustainable practices and their effect on environmental, economic and productivity outcomes. We find that independent of the incentive type, programmes linked to short-term economic benefit have a higher adoption rate than those aimed solely at providing an ecological service. In the long run, one of the strongest motivations for farmers to adopt sustainable practices is perceived benefits for either their farms, the environment or both. Beyond this, the importance of technical assistance and extension services in promoting sustainable practices emerges strongly from this scoping review. Finally, we find that policy instruments are more effective if their design considers the characteristics of the target population, and the associated trade-offs between economic, environmental and social outcomes.
A scoping review of interventions for crop postharvest loss reduction in sub-Saharan Africa and South Asia
Authors: Stathers Tanya , Holcroft Deirdre , Kitinoja Lisa , Mvumi Brighton M. , English Alicia , Omotilewa Oluwatoba , Kocher Megan , Ault Jessica , Torero Maximo 
Published: October 2020

AbstractReducing postharvest losses (PHLs) of food crops is a critical component of sustainably increasing agricultural productivity. Many PHL reduction interventions have been tested, but synthesized information to support evidence-based investments and policy is scarce. In this study, PHL reduction interventions for 22 crops across 57 countries in sub-Saharan Africa and South Asia from the 1970s to 2019 were systematically reviewed. Screening of the 12,907 studies identified resulted in a collection of 334 studies, which were used to synthesize the evidence and construct an online open-access database, searchable by crop, country, postharvest activity and intervention type. Storage technology interventions mainly targeting farmers dominated (83% of the studies). Maize was the most studied crop (25%). India had the most studies (32%), while 25 countries had no studies. This analysis indicates an urgent need for a systematic assessment of interventions across the entire value chain over multiple seasons and sites, targeting stakeholders beyond farmers. The lack of studies on training, finance, infrastructure, policy and market interventions highlights the need for interventions beyond technologies or handling practice changes. Additionally, more studies are needed connecting the impact of PHL reductions to social, economic and environmental outcomes related to Sustainable Development Goals. This analysis provides decision makers with data for informed policy formulation and prioritization of investments in PHL reduction.
Spin rates of V-type asteroids
Authors: Oszkiewicz Dagmara , Troianskyi Volodymyr , Föhring Dóra , Galád Adrián , Kwiatkowski Tomasz , Marciniak Anna , Skiff Brian A. , Geier Stefan , Borczyk Wojciech , Moskovitz Nicholas A. , Kankiewicz Paweł , Gajdoš Štefan , Világi Jozef , Polčic L’udovít , Kluwak Tomasz , Wilawer Emil , Kashuba Volodymyr , Udovichenko Sergei , Keir Leonid , Kamiński Krzysztof , Devogele Maxime , Gustafsson Annika 
Published: October 2020

Context. Basaltic V-type asteroids play a crucial role in studies of Solar System evolution and planetesimal formation. Comprehensive studies of their physical, dynamical, and statistical properties provide insight into these processes. Thanks to wide surveys, currently there are numerous known V-type and putative V-type asteroids, allowing a detailed statistical analysis.
Aims. Our main goal is to analyze the currently available large sample of V-type spin rates, to find signatures of the non-gravitational Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect among the different V-type populations, and to estimate the spin barrier and critical density for V-type asteroids. Our intention is to increase the pool of information about the intriguing V-types.
Methods. We collected rotational periods from the literature for spectrally confirmed V-types, putative V-types, and Vesta family members. Through spectroscopic observations we confirmed their taxonomic type and verified the high confirmation rates of the putative V-types. We combined the collected periods with periods estimated in this manuscript and produced rotational frequency distributions. We determined the spin barrier in the frequency–light curve amplitude space for V-type asteroids.
Results. We analyzed rotational periods of 536 asteroids in our sample. As expected, due to the small size of the objects analyzed, the frequency distributions for the Vesta family and the V-types outside the family are inconsistent with a Maxwellian shape. The Vesta family shows an excess of slow-rotators. V-types outside the family show an excess of both slow and fast rotators. Interestingly, we found that the population of V-types outside the Vesta family shows a significant excess of fast rotators compared to the Vesta family. The estimated critical density for V-type asteroids exceeds ρc = 2.0 g cm−3, which surpasses the previous estimates.
Conclusions. We demonstrated that V-type asteroids have been influenced by the thermal radiation YORP effect and that their critical spin rate is higher than for C-type asteroids. The population of V-types outside the Vesta family shows a significant excess of fast rotators compared to the Vesta family. We hypothesize that the objects that evolved from the Vesta family though the Yarkovsky drift are also more susceptible to the YORP effect. Objects for which YORP has not yet had enough time to act and those that are more YORP resistant will be left in the family, which explains the relatively small proportion of fast rotators being left. The YORP timescale must thus be similar to the migration timescale for those objects.
Thorough characterisation of the 16 Cygni system
Authors: Farnir M. , Dupret M.-A. , Buldgen G. , Salmon S. J. A. J. , Noels A. , Pinçon C. , Pezzotti C. , Eggenberger P. 
Published: October 2020

Context.Being part of the brightest solar-like stars, and close solar analogues, the 16 Cygni system is of great interest to the scientific community and may provide insight into the past and future evolution of our Sun. It has been observed thoroughly by theKeplersatellite, which provided us with data of an unprecedented quality.Aims.This paper is the first of a series aiming to extensively characterise the system. We test several choices of micro- and macro-physics to highlight their effects on optimal stellar parameters and provide realistic stellar parameter ranges.Methods.We used a recently developed method, WhoSGlAd, that takes the utmost advantage of the whole oscillation spectrum of solar-like stars by simultaneously adjusting the acoustic glitches and the smoothly varying trend. For each choice of input physics, we computed models which account, at best, for a set of seismic indicators that are representative of the stellar structure and are as uncorrelated as possible. The search for optimal models was carried out through a Levenberg-Marquardt minimisation. First, we found individual optimal models for both stars. We then selected the best candidates to fit both stars while imposing a common age and composition.Results.We computed realistic ranges of stellar parameters for individual stars. We also provide two models of the system regarded as a whole. We were not able to build binary models with the whole set of choices of input physics considered for individual stars as our constraints seem too stringent. We may need to include additional parameters to the optimal model search or invoke non-standard physical processes.
Non-LTE inversions of a confined X2.2 flare
Authors: Vissers G. J. M. , Danilovic S. , de la Cruz Rodríguez J. , Leenaarts J. , Morosin R. , Díaz Baso C. J. , Reid A. , Pomoell J. , Price D. J. , Inoue S. 
Published: October 2020

Context. Obtaining an accurate measurement of magnetic field vector in the solar atmosphere is essential for studying changes in field topology during flares and reliably modelling space weather.
Aims. We tackle this problem by applying various inversion methods to a confined X2.2 flare that occurred in NOAA AR 12673 on 6 September 2017 and comparing the photospheric and chromospheric magnetic field vector with the results of two numerical models of this event.
Methods. We obtained the photospheric magnetic field from Milne-Eddington and (non-)local thermal equilibrium (non-LTE) inversions of Hinode SOT/SP Fe I 6301.5 Å and 6302.5 Å. The chromospheric field was obtained from a spatially regularised weak-field approximation (WFA) and non-LTE inversions of Ca II 8542 Å observed with CRISP at the Swedish 1 m Solar Telescope. We investigated the field strengths and photosphere-to-chromosphere shear in the field vector.
Results. The LTE- and non-LTE-inferred photospheric magnetic field components are strongly correlated across several optical depths in the atmosphere, with a tendency towards a stronger field and higher temperatures in the non-LTE inversions. For the chromospheric field, the non-LTE inversions correlate well with the spatially regularised WFA, especially in terms of the line-of-sight field strength and field vector orientation. The photosphere exhibits coherent strong-field patches of over 4.5 kG, co-located with similar concentrations exceeding 3 kG in the chromosphere. The obtained field strengths are up to two to three times higher than in the numerical models, while the photosphere-to-chromosphere shear close to the polarity inversion line is more concentrated and structured.
Conclusions. In the photosphere, the assumption of LTE for Fe I line formation does not yield significantly different magnetic field results in comparison to the non-LTE case, while Milne-Eddington inversions fail to reproduce the magnetic field vector orientation where Fe I is in emission. In the chromosphere, the non-LTE-inferred field is excellently approximated by the spatially regularised WFA. Our inversions confirm the locations of flux rope footpoints that have been predicted by numerical models. However, pre-processing and lower spatial resolution lead to weaker and smoother field in the models than what our data indicate. This highlights the need for higher spatial resolution in the models to better constrain pre-eruptive flux ropes.
Sustained oscillations in interstellar chemistry models
Authors: Roueff Evelyne , Le Bourlot Jacques 
Published: October 2020

Context. Nonlinear behavior in interstellar chemical models has been recognized for 25 years now. Different mechanisms account for the possibility of multiple fixed-points at steady-state, characterized by the ionization degree of the gas.
Aims. Chemical oscillations are also a natural behavior of nonlinear chemical models. We study under which conditions spontaneous sustained chemical oscillations are possible, and what kind of bifurcations lead to, or quench, the occurrence of such oscillations.
Methods. The well-known ordinary differential equations (ODE) integrator VODE was used to explore initial conditions and parameter space in a gas phase chemical model of a dark interstellar cloud.
Results. We recall that the time evolution of the various chemical abundances under fixed temperature conditions depends on the density over cosmic ionization rate nH∕ζ ratio. We also report the occurrence of naturally sustained oscillations for a limited but well-defined range of control parameters. The period of oscillations is within the range of characteristic timescales of interstellar processes and could lead to spectacular resonances in time-dependent models. Reservoir species (C, CO, NH3, ...) oscillation amplitudes are generally less than a factor two. However, these amplitudes reach a factor ten to thousand for low abundance species, e.g. HCN, ND3, that may play a key role for diagnostic purposes. The mechanism responsible for oscillations is tightly linked to the chemistry of nitrogen, and requires long chains of reactions such as found in multi-deuteration processes.
Hydride Approach in Blended Elemental Powder Metallurgy of Beta Titanium Alloys
Authors: Ivasishin O.M. , Savvakin D.G. , Oryshych D.V. , Stasiuk O.O. , Yuanyuan Li 
Published: October 2020

The physical bases of hydrogenated titanium powders application in blended elemental powder metallurgy (BEPM) of titanium alloys were earlier developed. Hydrogen as temporary alloying addition for titanium strongly affects diffusion processes upon transformation of powder blends into alloys ensuring production of α+β and metastable β titanium alloys which mechanical properties meet standard requirements. At the same time, synthesis of metastable β alloys is complicated by a big amount of alloying elements which diffusion redistribution upon sintering has a strong impact on microstructure evolution.
In present study BEPM hydride approach was expanded for production of biocompatible low modulus Ti-Zr-Nb and Ti-Zr-Nb-Ta alloys having BCC structure which are attractive materials for medical application. The alloys of prescribed compositions were produced using various starting powders, including TiH2, ZrH2, hydrogenated niobium, tantalum and Ti-Nb master alloys. Peculiarities of volume changes of multicomponent powder blends on dehydrogenation were investigated. The specific volume changes of powder components during dehydrogenation affect densification kinetic of powder blends and microstructure of as-sintered alloys.
Influence of wire arc additive manufacturing of Ti-6Al-4V on microstructure and mechanical properties for potential large-scale aviation parts
Authors: Elitzer D. , Höppel H.W. , Göken M. , Baier D. , Fuchs C. , Bähr H. , Meyer T. , Gallasch A. 
Published: October 2020

As one of the most common Titanium alloys, Ti-6Al-4V faces new challenges concerning the ecological footprint. Due to the current processes, a high metal chip pollution leads to a Buy-to-Fly of 25:1.
In this study the parameter / microstructure relationship of Ti-64 on the mechanical properties are discussed. Wire Arc Additive Manufacturing (WAAM) was applied to build samples for microstructural analyses and compression tests. A stress relief (SR) and a solution treatment and annealing (STA) was performed. It was found that SR had no influence on multi-layered samples due to intrinsic heat-treatment. A STA heat-treatment led to a reduction in the mechanical strength. Helium as process gas resulted in an increased mechanical strength due to higher heat capacity compared to argon.
Effect of Microstructure on Fatigue Properties of Several Ti-Alloys for Aerospace Application
Authors: El-Chaikh A. , Danzig A. , Muenter D. 
Published: October 2020

A wide range of available Ti-alloys is used atLiebherr-Aerospace Lindenberg GmbHfor several aeronautical applications in flight controls and landing gear systems. For these applications, the mechanical properties of conventionally manufactured Ti-alloys (α+β, near β) as well as additive manufactured Ti-alloy were optimized.Modification of the heat treatment parameters of a near-β titanium alloy leads to optimization of the hardening process of large cross-sections. This modification allows the adjustment of an optimum volume fraction of the primary α-phase resulting in enhancing of the elongation, fracture toughness and fatigue properties.For a fatigue critical forging part from (α+β)-alloy a slight modification of the chemical composition combined with an additional heat treatment step during the forging process was performed. The adjusted microstructure of the modified process exhibits better fatigue behavior when compared to the conventional microstructure.Ti6Al4V parts produced by Additive Manufacturing, printed with optimized parameters and followed by heat treatment will result in reasonable fatigue properties in all printing directions, reducing the anisotropy of the printed parts.These improvements bringLiebherr-Aerospace Lindenberg GmbHin the position to adapt the used titanium alloys for the needs in a wide range.For the evaluation of the microstructure, light and scanning electron microscopes were used. Furthermore a model described in the “Metallic Materials Properties Development and Standardization” (MMPDS) was modified and used for the evaluation of the fatigue results.
Damage mechanisms and embrittlement kinetics in a β-rich Ti 17 alloy after long term aging
Authors: SASAKI Layla , HENAFF Gilbert , ARZAGHI Mandana , VILLECHAISE Patrick , HEMERY Samuel , DELFOSSE Jérôme 
Published: October 2020

The Ti 17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) alloy is used in the first stages of engine compressors, at temperatures up to 450°C. However, its use in structural parts such as engine pylons is more prospective and raises the question of damage tolerance. As the engine pylon environment involves prolonged exposures to high temperatures, the impact of aging on mechanical properties has also to be taken in account.In this work, the consequences of a long-term aging (up to 10 000 h at 450°C) on the mechanical resistance of a Ti 17 alloy are examined at different scales, from macroscopic fatigue crack growth tests to in-situ tensile tests performed on micro samples in a SEM. The detrimental effect of aging on the mechanical properties of the Ti 17 alloy was then discussed in the light of damage mechanisms analysis and embrittlement kinetics.
Titanium Production via Titanium Sulfide
Authors: Suzuki R. O. , Yashima Y. , Suzuki N. , Ahmadi E. , Natsui S. , Kikuchi T. 
Published: October 2020

A new metallurgical process via titanium sulfide from ilmenite is proposed and experimentally approved: It consists of several stages; 1) The ilmenite ore is exposed to gaseous CS2 to selectively sulfurize to FeS, which is wet-chemically removed. 2) The residual oxide is again exposed to CS2 to form TiS2. 3) TiS2 is electrochemically reduced to metallic Ti using molten CaCl2-CaS as an application of OS process.
TiFeO3 was exposed to Ar-CS2 mixed gas flow at 1173 K to form the mixture of FeS+TiO2. FeS was easily separated by immersing in H2SO4 solution at 313 K. After recovery of TiO2, it was converted completely to TiS2 by the second sulfurization with CS2. TiS2 could be reduced to Ti powder by calciothermic reduction and simulteneous electrolysis in a CaS-CaCl2 melt for about 6 hours at 1173 K and 3.0 V. The impurity decreased to a low level such as 0.021 mass%S due to very small solubility of S in a-Ti. However, 1.06 mass%O remained because of wide solubility of oxygen in a-Ti and water contamination in initial CaCl2.