Schauder estimates for a degenerate second order elliptic operator on a cube

AbstractIn the present article we are concerned with a class of degenerate second order differential operators LA,b defined on the cube [0,1]d, with d⩾1. Under suitable assumptions on the coefficients A and b (among them the assumption of their Hölder regularity) we show that the operator LA,b defined on C2([0,1]d) is closable and its closure is m-dissipative. In particular, its closure LA,b¯ is the generator of a C0-semigroup of contractions on C([0,1]d) and C2([0,1]d) is a core for it. The proof of such result is obtained by studying the solvability in Hölder spaces of functions of the elliptic problem λu(x)−LA,bu(x)=f(x), x∈[0,1]d, for a sufficiently large class of functions f

Syrian refugees in Greece: experience with violence, mental health status, and access to information during the journey and while in Greece.

BACKGROUND: Since 2015, Europe has been facing an unprecedented arrival of refugees and migrants: more than one million people entered via land and sea routes. During their travels, refugees and migrants often face harsh conditions, forced detention, and violence in transit countries. However, there is a lack of epidemiological quantitative evidence on their experiences and the mental health problems they face during their displacement. We aimed to document the types of violence experienced by migrants and refugees during their journey and while settled in Greece, and to measure the prevalence of anxiety disorders and access to legal information and procedures. METHODS: We conducted a cross-sectional population-based quantitative survey combined with an explanatory qualitative study in eight sites (representing the range of settlements) in Greece during winter 2016/17. The survey consisted of a structured questionnaire on experience of violence and an interviewer-administered anxiety disorder screening tool (Refugee Health Screener). RESULTS: In total, 1293 refugees were included, of whom 728 were Syrians (41.3% females) of median age 18 years (interquartile range 7-30). Depending on the site, between 31% and 77.5% reported having experienced at least one violent event in Syria, 24.8-57.5% during the journey to Greece, and 5-8% in their Greek settlement. Over 75% (up to 92%) of respondents ≥15 years screened positive for anxiety disorder, which warranted referral for mental health evaluation, which was only accepted by 69-82% of participants. Access to legal information and assistance about asylum procedures were considered poor to non-existent for the majority, and the uncertainty of their status exacerbated their anxiety. CONCLUSIONS: This survey, conducted during a mass refugee crisis in a European Community country, provides important data on experiences in different refugee settings and reports the high levels of violence experienced by Syrian refugees during their journeys, the high prevalence of anxiety disorders, and the shortcomings of the international protective response

TALON: hybrid education

TALON – the Teaching and Learning Online Network – is a University of Calgary project made possible by the Richard Parker Initiative (RPI). TALON is a hub for critical discussion of new and emerging education approaches and tools. Born in the early stages of the pandemic, shortly following the shutdown of in-person classes across the globe, we seek to document the ongoing changes within higher education and share thoughts, ideas, and experiences about online, blended and hybrid education. TALON's initiatives include A-Z resources, monthly newsletters, interviews with academic professionals and students, in-person activations and various publications. Combined, the projects serve as an interactive lexicon for remote teaching and learning. We keep the academic community informed about current developments in the virtual classroom and connected through discussion. Questions such as: What are the opportunities and challenges with hybrid education? What equipment is needed for effective blended learning? How can face-to-face, online, and other 'out of class' activities be integrated to foster student success? What assessment methods work well in a hybrid classroom? Is hybrid learning the future of education? – are addressed and discussed

AB Aur, a Rosetta stone for studies of planet formation (I): chemical study of a planet-forming disk

AB Aur is a Herbig Ae star that hosts a prototypical transition disk. The disk shows a plethora of features connected with planet formation mechanisms. Understanding the physical and chemical characteristics of these features is crucial to advancing our knowledge of planet formation. We aim to characterize the gaseous disk around the Herbig Ae star AB Aur. A complete spectroscopic study was performed using NOEMA to determine the physical and chemical conditions. We present new observations of the continuum and 12CO, 13CO, C18O, H2CO, and SO lines. We used the integrated intensity maps and stacked spectra to derive estimates of the disk temperature. By combining our 13CO and C18O observations, we computed the gas-to-dust ratio along the disk. We also derived column density maps for the different species and used them to compute abundance maps. The results of our observations were compared with Nautilus astrochemical models. We detected continuum emission in a ring that extends from 0.6 to 2.0 arcsec, peaking at 0.97 and with a strong azimuthal asymmetry. The molecules observed show different spatial distributions, and the peaks of the distributions are not correlated with the binding energy. Using H2CO and SO lines, we derived a mean disk temperature of 39 K. We derived a gas-to-dust ratio that ranges from 10 to 40. The comparison with Nautilus models favors a disk with a low gas-to-dust ratio (40) and prominent sulfur depletion. From a very complete spectroscopic study of the prototypical disk around AB Aur, we derived, for the first time, the gas temperature and the gas-to-dust ratio along the disk, providing information that is essential to constraining hydrodynamical simulations.Moreover, we explored the gas chemistry and, in particular, the sulfur depletion. The derived sulfur depletion is dependent on the assumed C/O ratio. Our data are better explained with C/O ~ 0.7 and S/H=8e-8.Comment: 13 figures, 6 table

Microstructure and mechanical properties of high strength steel deposits obtained by Wire-Arc Additive Manufacturing

Wire-arc additive manufacturing has become an alternative way to produce industrial parts. In this work 15 kg walls are built with an effective building rate of 4.85 kg/h using an ER100 wire providing good tensile properties and toughness under welding conditions. The thermal evolution of the walls during manufacturing is measured by thermocouples and an IR camera: it depends on process parameters, deposit strategy and the size of the part. The walls are then characterised as deposit and after heat treatment through hardness, tensile and Charpy-V notch tests. The results show a fine microstructure with unexpected retained austenite and coarse allotriomorphic ferrite in the as deposited walls. The final hardness values vary from about 220 to 280 HV2; the yield stress and tensile strength are 520 and 790 MPa, respectively, and a toughness of about 50 J is obtained at room temperature. The heat treatment transforms the retained austenite, leading to an improvement of the yield stress to 600 MPa

Plant growth drives soil nitrogen cycling and N-related microbial activity through changing root traits

Relationships between plants and nitrogen-related microbes may vary with plant growth. We investigated these dynamic relationships over three months by analyzing plant functional traits (PFT), arbuscular mycorrhizal fungal (AMF) colonization, potential N mineralization (PNM), potential nitrification (PNA) and denitrification activities (PDA) in Dactylis glomerata cultures. D. glomerata recruited AMF during early growth, and thereafter maintained a constant root colonization intensity. This may have permitted high enough plant nutrient acquisition over the three months as to offset reduced soil inorganic N. PFT changed with plant age and declining soil fertility, resulting in higher allocation to root biomass and higher root C:N ratio. Additional to root AMF presence, PR' changes may have favored denitrification over mineralization through changes in soil properties, particularly increasing the quality of the labile carbon soil fraction. Other PFT changes, such as N uptake, modified the plants' ability to compete with bacterial groups involved in N cycling. (C) 2020 Elsevier Ltd and British Mycological Society. All rights reserved.Peer reviewe

Osmotic Stress and ABA Affect Immune Response and Susceptibility of Grapevine Berries to Gray Mold by Priming Polyamine Accumulation

Abiotic factors inducing osmotic stress can affect plant immunity and resistance against pathogen attack. Although a number of studies have characterized grapevine responses to various forms of biotic and abiotic stresses, the relationships between osmotic stress response and susceptibility of mature berries to Botrytis cinerea still remain unknown. In this study, we investigated the effects of osmotic stress and abscisic acid (ABA) on defense responses of mature grapevine berries before and after B. cinerea infection. We focused on the possible involvement of polyamines in the interaction between osmotic stress response and susceptibility to B. cinerea. We showed that osmotic stress induced by PEG or sucrose, and exogenous ABA induce transient but low defense responses, including weak expression of PR genes and phytoalexin synthesis in mature berries. This was accompanied by an upregulation of NCED2 involved in ABA biosynthesis and a large production of free polyamines. However, osmotic stress followed by B. cinerea infection primed berries for enhanced accumulation of polyamines, but slowed down the defense responses and increased susceptibility to the pathogen. A weak increase of diamine- and polyamine-oxidase activities was also recorded in stressed berries, but declined after pathogen infection. The pretreatment of stressed berries with appropriate inhibitors of diamine- and polyamine-oxidases further increased polyamine level and greatly lowered defense responses, leading to higher susceptibility to B. cinerea. These results suggest that increased polyamine titer through low activation of their oxidative degradation in grape berries may contribute at least in part to the weakening of defense responses and subsequent disease susceptibility

Comparison of inorganic nitrogen uptake dynamics following snowmelt and at peak biomass in subalpine grasslands

Subalpine grasslands are highly seasonal environments and likely subject to strong variability in nitrogen (N) dynamics. Plants and microbes typically compete for N acquisition during the growing season and particularly at plant peak biomass. During snowmelt, plants could potentially benefit from a decrease in competition by microbes, leading to greater plant N uptake associated with active growth and freeze-thaw cycles restricting microbial growth. In managed subalpine grasslands, we expect these interactions to be influenced by recent changes in agricultural land use, and associated modifications in plant and microbial communities. At several subalpine grasslands in the French Alps, we added pulses of 15N to the soil at the end of snowmelt, allowing us to compare the dynamics of inorganic N uptake in plants and microbes during this period with that previously reported at the peak biomass in July. In all grasslands, while specific shoot N translocation (per g of biomass) of dissolved inorganic nitrogen (DIN) was two to five times greater at snowmelt than at peak biomass, specific microbial DIN uptakes were similar between the two sampling dates. On an area basis, plant communities took more DIN than microbial communities at the end of snowmelt when aboveground plant biomasses were at least two times lower than at peak biomass. Consequently, inorganic N partitioning after snowmelt switches in favor of plant communities, allowing them to support their growing capacities at this period of the year. Seasonal differences in microbial and plant inorganic N-related dynamics were also affected by past (terraced vs. unterraced) rather than current (mown vs. unmown) land use. In terraced grasslands, microbial biomass N remained similar across seasons, whereas in unterraced grasslands, microbial biomass N was higher and microbial C : N lower at the end of snowmelt as compared to peak biomass. Further investigations on microbial community composition and their organic N uptake dynamics are required to better understand the decrease in microbial DIN uptake.Peer reviewe

Representativeness of the European social partner organisations : Sea fisheries sector

Aquesta publicació s'elabora a partir de les contribucions de cadascú dels membres nacionals que integren la Network of Eufound Correspondent. Pel cas d'Espanya la contribució ha estat realitzada per l'Alejandro GodinoThis study provides information allowing for an assessment of the representativeness of the actors involved in the European sectoral social dialogue committee for the sea fisheries sector. Their relative representativeness legitimises their right to be consulted, their role and effective participation in the European sectoral social dialogue and their capacity to negotiate agreements. The aim of Eurofound's representativeness studies is to identify the relevant national and European social partner organisations. This study identified the Association of National Organisations of Fishing Enterprises in the European Union (Europêche) (representing employers) and European Transport Workers' Federation (ETF) (representing employees) as the most representative European level social partner organisations in the sea fisheries sector. COPA-COGECA, representing employers in the primary sector, has also some representativeness in the sector

Representativeness of the European social partner organisations : human health sector

Aquesta publicació s'elabora a partir de les contribucions de cadascú dels membres nacionals que integren la Network of Eufound Correspondent. Pel cas d'Espanya la contribució ha estat realitzada per l'Oscar MolinaThis study provides information allowing for an assessment of the representativeness of the actors involved in the European sectoral social dialogue committee for the human health sector. Their relative representativeness legitimises their right to be consulted, their role and effective participation in the European sectoral social dialogue, and their capacity to negotiate agreements. The aim of Eurofound's studies on representativeness is to identify the relevant national and European social partner organisations in the field of industrial relations in the EU Member States. This study identified the European Federation of Public Service Unions (EPSU) - representing employees - and the European Hospital and Healthcare Employers' Association (HOSPEEM) - representing employers - as the most representative European-level social partner organisations in the human health sector. The member organisations of the European Confederation of Independent Trade Unions (CESI) and UNI Europa also organise employees in the sector in several Member States