A comparison of Finite Elements for Nonlinear Beams: The absolute nodal coordinate and geometrically exact formulations

Two of the most popular finite element formulations for solving nonlinear beams are the absolute nodal coordinate and the geometrically exact approaches. Both can be applied to problems with very large deformations and strains, but they differ substantially at the continuous and the discrete levels. In addition, implementation and run-time computational costs also vary significantly. In the current work, we summarize the main features of the two formulations, highlighting their differences and similarities, and perform numerical benchmarks to assess their accuracy and robustness. The article concludes with recommendations for the choice of one formulation over the other

LBBG_JUVENILE - Juvenile lesser black-backed gulls (Larus fuscus, Laridae) hatched in Zeebrugge (Belgium)

<p><i>LBBG_JUVENILE - Juvenile lesser black-backed gulls (Larus fuscus, Laridae) hatched in Zeebrugge (Belgium)</i> is a bird tracking dataset published by the <a href="https://www.inbo.be/en">Research Institute for Nature and Forest (INBO)</a>. It contains animal tracking data collected by the LifeWatch GPS tracking network for large birds (<a href="http://lifewatch.be/en/gps-tracking-network-large-birds">http://lifewatch.be/en/gps-tracking-network-large-birds</a>) for the project/study <strong>LBBG_JUVENILE</strong>, using trackers developed by Ornitela (<a href="https://www.ornitela.com">https://www.ornitela.com</a>). The study has been operational since 2020. In total 92 individuals of lesser black-backed gull (<i>Larus fuscus</i>) have been tagged shortly after fledging in the colony of Zeebrugge, mainly to study their habitat use and migration behaviour. Data are automatically synced with Movebank and from there periodically archived on Zenodo (see <a href="https://github.com/inbo/bird-tracking">https://github.com/inbo/bird-tracking</a>).</p><p>Data in this package are exported from Movebank study <i>LBBG_JUVENILE - Juvenile lesser black-backed gulls (Larus fuscus, Laridae) hatched in Zeebrugge (Belgium)</i> (Movebank Study ID 1259686571), which can be viewed at <a href="https://www.movebank.org/cms/webapp?gwt_fragment=page=studies,path=study1259686571">https://www.movebank.org/cms/webapp?gwt_fragment=page=studies,path=study1259686571</a>. Fields in the data follow the Movebank Attribute Dictionary (<a href="http://vocab.nerc.ac.uk/collection/MVB">http://vocab.nerc.ac.uk/collection/MVB</a>) and are described in datapackage.json.</p><p><strong>Files</strong></p><p>Files are structured as a <a href="https://specs.frictionlessdata.io/data-package/">Frictionless Data Package</a>. You can access all data in R via https://zenodo.org/record/6579643/files/datapackage.json using <a href="https://frictionlessdata.github.io/frictionless-r/">frictionless</a>.</p><ul><li><strong>datapackage.json</strong>: technical description of the data files.</li><li><strong>LBBG_JUVENILE-reference-data.csv</strong>: reference data about the animals, tags and deployments.</li><li><strong>LBBG_JUVENILE-gps-yyyy.csv.gz</strong>: GPS data recorded by the tags, grouped by year.</li></ul>This dataset was collected using infrastructure provided by INBO and funded by Research Foundation - Flanders (FWO) as part of the Belgian contribution to LifeWatch

Influence of processing and storage conditions on the mechanical and barrier properties of films cast from aqueous wheat gluten dispersions

A method was developed to prepare films based on industrial wheat gluten, from aqueous dispersion at neutral pH. An essential step in this procedure is to prepare aqueous dispersions in such a way that coagulation of the vital wheat gluten is prevented. In contrast to current procedures, adjustment of the pH or addition of organic solvents can be avoided. It was shown that processing variables, e.g. pH and drying temperature, influenced the properties of the films (containing 20% (w/w) of glycerol). The moisture content of the films had an even larger influence on the properties of the film than the processing conditions. At a relative humidity of 11 and 79%, films showed a stress and strain of about 23 MPa and 1%, and 1.6 MPa and 350%, respectively. It was shown that these variations are a result of the influence of the moisture content on the glass transition temperature of wheat gluten

Resource predictability drives interannual variation in migratory behavior in a long-lived bird

We use GPS tracking data on 28 adult Lesser Black-backed Gulls to show how these long-lived birds benefit from experience during migration. We found that stopover fidelity across years strongly depended on food source reliability. Birds using more reliable food sources thereby showed more consistent migratory behavior across years and covered significantly less distance while foraging during stopovers. There is a growing awareness that experience may play a major role in migratory decisions, especially in long-lived species. However, empirical support remains to date scarce. Here, we use multiyear GPS-tracking data on 28 adult Lesser Black-backed Gulls (Larus fuscus), a long-lived species for which migratory strategies typically consist of a series of long stopovers, to assess how experience affects interannual variation in stopover selection. We expect that food source reliability should play a pivotal role, as it both reduces the uncertainty on food availability across years, and enables for more efficient foraging during stopovers by reducing searching efforts. We found that during stopovers gulls indeed developed high fidelity to particular foraging locations, which strongly reduced the daily distance travelled for foraging. When revisiting stopovers in consecutive years, birds used over 80% of foraging locations from the previous year. Although the average fidelity to stopovers across years was a high as 85%, stopovers where birds showed high foraging site fidelity were up to 60% more likely to be revisited compared to stopover with low foraging site fidelity. Accordingly, birds using more stopovers with reliable foraging opportunities showed significantly less interannual variation in their stopover use than birds using stopovers with less reliable foraging opportunities. Our results thus highlight the need to further deepen our understanding of the role of cognitive processes in individual variation in migratory behavior

Weather- and human-related shifts in feeding conditions promote the use of built-up areas by an avian opportunist

Human activities benefit a range of animal species, the resulting presence of which in cities can have negative societal consequences. One example are food subsidies, which buffer natural variation in food availability and allow these species to maintain larger populations. These buffers will likely gain importance under future environmental change whereby natural food sources become decreasingly available. To inform on the current importance of different habitats for a bird reliant on human-made food subsidies (Lesser Black-backed Gull Larus fuscus), and its possible population response toward changes in climate and the availability of these subsidies, we characterized population-level short-term responses to variation in drivers of local food availability, both natural (weather related) and anthropogenic (fisheries activity). We expected foraging effort to vary in relation to local wind speed and soil moisture, as well as to the alternation of fisheries activity between weekdays and weekends. Individuals were predicted to adjust their foraging habitat use in response to these environmentally driven variations in effort. To this end, we analyzed GPS tracking data of 45 breeding individuals, between 2013 and 2018, nesting in the Port of Zeebrugge, Belgium. Effort was approximated as the energy expenditure rate per trip, the daily time spent away from the colony and the trip frequency, which were analyzed by means of linear mixed effects models. Habitat use per trip was compared between marine, agricultural fields and built-up areas (cities, industry and cattle farms), in a multinomial logistic model. Marine areas and agricultural fields were most frequently exploited, but all considered stressors (wind, dry conditions and inactivity of fisheries) resulted in a higher use of built-up areas. Stronger winds increased the energetic cost of foraging at sea, and thus diminished the use of marine areas, as also did the inactivity of fisheries in weekends. Dry conditions diminished the use of fields and decreased trip frequency. Built-up areas thus constitute a buffer for the variation in food availability at sea and in agricultural fields. The expected increase in frequency and severity of extreme weather events (storms and drought) under global change, combined with the disappearance of discards, may therefore result in a longterm increase in the use of urban habitats by opportunistic large Gull species

Attracted to the outside : a meso-scale response pattern of lesser black-backed gulls at an offshore wind farm revealed by GPS telemetry

Among seabirds, lesser black-backed gulls (Larus fuscus) are considered to be at high risk of colliding with offshore wind turbines. In this respect, we used GPS tracking data of lesser black-backed gulls caught and tagged in two colonies along the Belgian North Sea coast (Ostend and Zeebrugge) to study spatial patterns in the species’ presence and behaviour in and around the Thornton Bank offshore wind farm (OWF). We found a significant decrease in the number of GPS fixes of flying birds from up to a distance of at least 2000 m towards the middle of the wind farm. Non-flying birds showed a similar avoidance of the wind farm interior, yet presence strongly peaked right at the wind farm’s edge, demonstrated to represent gulls perching on the outer turbine jacket foundations. The findings of this study reveal a strong within-wind farm variability in bird density, a most crucial parameter in collision risk modelling. The method presented here is straightforward and similar studies conducted at other wind farm sites on a range of large gull species (Larus sp.) would allow to assess the potential and species-specific variation in meso-scale response patterns and to gain insight in the underlying ecological incentives, which in turn would provide widely applicable and much-needed input for (cumulative) collision impact assessments