On traces for H(curl,Ω) in Lipschitz domains

AbstractWe study tangential vector fields on the boundary of a bounded Lipschitz domain Ω in R3. Our attention is focused on the definition of suitable Hilbert spaces corresponding to fractional Sobolev regularities and also on the construction of tangential differential operators on the non-smooth manifold. The theory is applied to the characterization of tangential traces for the space H(curl,Ω). Hodge decompositions are provided for the corresponding trace spaces, and an integration by parts formula is proved

Cross-habitat usage by crop aphids and their parasitoids in the cropnoncrop interface in an organic vegetable farm.

Plant-aphid-parasitoid interactions and parasitism rates were assessed in adjacent cultivated and noncultivated habitats in an organic vegetable farm in a chaco serrano woodland, Córdoba, Argentina. Seven aphid species on eight vegetable species were found in the cultivated habitat. Macrosiphum euphorbiae was present on all vegetable species. Four parasitoid species were recorded, of which Diaretiella rapae was the most common. It provided 21.32% of parasitism on Brevicoryne brassicae. In the non-cultivated habitat, 36 plant species hosted 22 aphid species and five parasitoid species. The aphid Myzus persicae was present on 17 plant species of eight different families. Macrosiphoniella artemisiae was the most abundant aphid species, with the associated Aphidius sp. being the most abundant parasitoid. Aphidius polygonaphis provided 10% of parasitism on Uroleucon aeneus. We report several wild plant species as important reservoirs of parasitoids, which are potential controllers of many pest aphid species

Solid state joining of thin hybrid sandwiches made of steel and polymer: A feasibility study

The growing demand for more environmentally friendly vehicles has led to an increased use of light materials in the transportation industry with the aim to reduce structural weight, fuel consumption, and gas emissions, thereby boosting cost-effectiveness and recyclable properties. Complex multi-material steel-based components would allow to improve mechanical properties and minimize weight even further. In particular, new sandwich materials made by steel outer skins and a polymeric internal layer seems very promising for obtaining mechanical performance and lightness at the same time. Unfortunately, traditional welding techniques, like arc welding, laser welding, and resistance spot welding, usually used to join steels and aluminum alloys, cannot be applied for these materials due to their peculiar nature. In this paper, the feasibility of Friction Stir Welding to join thin sandwich components made of two steel outer layers and an internal polymeric layer was assessed. Both a pin and a pinless tool were used to weld the upper and the lower surface of the joint in order to obtain solid state bonding of the metal and fusion welding of the polymer at the same time. © 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 23rd International Conference on Material Forming

The germination niche of coastal dune species as related to their occurrence along a sea–inland gradient

Aims: The early phases in the life cycle of a plant are the bottleneck for successful species establishment thereby affecting population dynamics and distribution. In coastal environments, the spatial pattern of plant communities (i.e. vegetation zonation) follows the ecological gradient of abiotic stress changing with the distance from the sea. This pattern has been mainly explained based on the adaptation and tolerance to the abiotic stress of adult plants. However, the adult niche may considerably differ from the germination niche of a plant species. The aim of this work was to investigate to what extent abiotic factors (specifically salinity, temperature, nitrogen and their interactions) constrain seed germination along the sea–inland gradient. Location: Latium coast (Central Italy). Methods: Germination tests were performed on seeds of focal species of three different plant communities which establish at increasing distances from the coastline: Cakile maritima subsp. maritima, Elymus farctus, Crucianella maritima. We tested increasing concentrations of NaCl (one of the main abiotic factors which decrease across the sea–inland gradient), and their interactions with temperature and KNO3, to consider other factors which drive germination processes. Results: The tolerance to salinity significantly decreased in relation to the position of species along the coastal zonation. Crucianella maritima was shown to be the least tolerant species, having a decrease in germination >80% across all conditions. KNO3 significantly (although slightly) increased the germination percentage in Cakile maritima subsp. maritima and Elymus farctus. When combined with NaCl, KNO3 alleviated the negative effects of salinity only in Cakile maritima subsp. maritima. Conclusions: The germination responses to the interaction among the tested factors suggest that the germination niche may explain vegetation zonation filtering species at their early stages. Quantifying environmental niches in different phases of the life cycle of plants may provide important insights into community assembly processes

Imaging of SNR IC443 and W44 with the Sardinia Radio Telescope at 1.5 GHz and 7 GHz

Observations of supernova remnants (SNRs) are a powerful tool for investigating the later stages of stellar evolution, the properties of the ambient interstellar medium, and the physics of particle acceleration and shocks. For a fraction of SNRs, multi-wavelength coverage from radio to ultra high-energies has been provided, constraining their contributions to the production of Galactic cosmic rays. Although radio emission is the most common identifier of SNRs and a prime probe for refining models, high-resolution images at frequencies above 5 GHz are surprisingly lacking, even for bright and well-known SNRs such as IC443 and W44. In the frameworks of the Astronomical Validation and Early Science Program with the 64-m single-dish Sardinia Radio Telescope, we provided, for the first time, single-dish deep imaging at 7 GHz of the IC443 and W44 complexes coupled with spatially-resolved spectra in the 1.5-7 GHz frequency range. Our images were obtained through on-the-fly mapping techniques, providing antenna beam oversampling and resulting in accurate continuum flux density measurements. The integrated flux densities associated with IC443 are S_1.5GHz = 134 +/- 4 Jy and S_7GHz = 67 +/- 3 Jy. For W44, we measured total flux densities of S_1.5GHz = 214 +/- 6 Jy and S_7GHz = 94 +/- 4 Jy. Spectral index maps provide evidence of a wide physical parameter scatter among different SNR regions: a flat spectrum is observed from the brightest SNR regions at the shock, while steeper spectral indices (up to 0.7) are observed in fainter cooling regions, disentangling in this way different populations and spectra of radio/gamma-ray-emitting electrons in these SNRs.Comment: 13 pages, 9 figures, accepted for publication to MNRAS on 18 May 201

Evidence for less marked potential signs of T-cell immunosenescence in centenarian offspring than in the general age-matched population

People may reach the upper limits of the human life span at least partly because they have maintained more appropriate immune function, avoiding changes to immunity termed "immunosenescence." Exceptionally long-lived people may be enriched for genes that contribute to their longevity, some of which may bear on immune function. Centenarian offspring would be expected to inherit some of these, which might be reflected in their resistance to immunosenescence, and contribute to their potential longevity. We have tested this hypothesis by comparing centenarian offspring with age-matched controls. We report differences in the numbers and proportions of both CD4(+) and CD8(+) early- and late-differentiated T cells, as well as potentially senescent CD8(+) T cells, suggesting that the adaptive T-cell arm of the immune system is more "youthful" in centenarian offspring than controls. This might reflect a superior ability to mount effective responses against newly encountered antigens and thus contribute to better protection against infection and to greater longevity

Habitats Directive in northern Italy: a series of proposals for habitat definition improvement

Habitats Directive (92/43/EEC) is the cornerstone of nature conservation in Europe and is at the core of the EU Biodiversity Strategy for 2030. There is room, however, for its improvement, at least for northern Italy, where ambiguities in the definition of habitat types of Annex I of the Habitats Directive are not novel and interpretation difficulties have been highlighted. Sharpening the characterization of habitat types represents an opportunity for lowering classification uncertainties and improving conservation success. With the aim to refine the definitions of habitat types and associated typical species of the Habitats Directive, a group of vegetation scientists of the Italian Society of Vegetation Science based in northern Italy made the exercise of finding viable proposals for those habitat types having a problematic interpretation in the Alpine biogeographical region of Italy. Such proposals arise from group discussions among scientists, and professionals, thus offering a shared view. We prepared 9 habitat proposals important for this geographic area. They include new habitat types at the European level, new subtypes within pre-existing habitat types, including some adjustments of the recently proposed subtypes with respect to northern Italy, and recognition of priority criteria for a pre-existing habitat type. With a vision of tailored conservation, our proposals represent a starting point in view of a future update of Annex I. Furthermore, the list of typical species could be useful for preparing expert systems for automatic classification. Irrespective of legally binding solutions in place, we caution these proposals represent relevant baseline conservation indications that local and regional administrations of the Alpine Arch should consider

Attendance effects of Camponotus rufipes (Fabricius) (Hymenoptera, Formicidae) on aggregations of Enchenopa sericea Walk. (Hemiptera, Membracidae)

Las agregaciones del membrácido Enchenopa sericea Walk. son atendidas por hormigas Camponotus rufipes (Fabricius) sobre brotes de Caesalpinia gilliesii (Wall. et Hook.) Dietr. en La Quebrada, Río Ceballos, provincia de Córdoba. Para conocer los efectos de esta atención sobre las oviposturas, ninfas y adultos del membrácido, se impidió la atención de hormigas a 25 agregaciones y otras 74 se utilizaron como controles; en ambos casos fueron censadas desde octubre de 1997 hasta marzo de 1998. Se registró una correlación entre el número total de hormigas y de membrácidos. El número promedio de ninfas aumentó en las agregaciones atendidas, como así también el de machos, hembras y la proporción de sexos. Las oviposturas no fueron atractivas para Camponotus rufipes. Las hembras de Enchenopa sericea aparentemente permanecieron más tiempo junto a las ovisposturas en las agregaciones no atendidas, lo que es interpretado como una forma de cuidado parental. Proporcionalmente, las hormigas atendieron un mayor número de adultos, lo que estaría relacionado con la cantidad de melado disponible.Enchenopa sericea Walk. (Membracidae), a gregarious, sap-feeding treehopper, is tended by the ant Camponotus rufipes (Fabricius) (Formicidae) on Caesalpinea gilliesii (Wall. et Hook.) Dietr. (Fabaceae) shrubs in La Quebrada, Río Ceballos, province of Córdoba. We investigated the effects of ant-attendance on eggs, nymphs and adults of the membracid. Local populations of the membracid and their associated ants were counted nondestructively at weekly intervals during 21 weeks from October 1997 to March 1998. Seventy-four ant-present aggregations (control) and 25 ant-excluded aggregations (unattended) were studied. The results of field censuses revealed a positive correlation between ants and membracids. Attendance greatly increases the mean number of surviving nymphs, reaching them higher numbers in ant-present aggregations than in ant-excluded aggregations. The mean number of females and males, and the sexual ratio, were greater when attended by the ants than where ants were excluded. Eggs were not attractive to Camponotus rufipes and no correlation was found with them. Enchenopa sericea females apparently remain longer with the egg masses in the absence of ants to attract them to the future group of nymphs, and this behaviour is interpreted as a form of parental care. Proportionally, ants attended adults in larger numbers than nymphs, suggesting that ant attendance can be related to the quantity of honeydew available