Search results for "feature"
showing 10 items of 4091 documents
Factors affecting breeding dispersal of European ducks on Engure Marsh, Latvia
2003
Summary 1 We used up to 35 years of capture–recapture data from nearly 3300 individual female ducks nesting on Engure Marsh, Latvia, and multistate modelling to test predictions about the influence of environmental, habitat and management factors on breeding dispersal probability within the marsh. 2 Analyses based on observed dispersal distances of common pochards and tufted ducks provided no evidence that breeding success in year t influenced dispersal distance between t and t+ 1. 3 Breeding dispersal distances (year t to t+ 1) of pochards and tufted ducks were associated with a delay in relative nest initiation dates in year t+ 1. The delay was greater for pochards (c. 4 days) than for tu…
Soviet era landscape change and the post-Soviet legacy in Latvia
2019
The collectivisation of agriculture and the development and application of land improvement “melioration” programmes and technologies, as well as the construction of kolkhoz centres during the Soviet era in Latvia was extensive and has a legacy on the post-Soviet landscape and agricultural economy. A study of a number of rural municipalities in different landscape types, through the comparison of maps from the early 20th century with those from around 2000, and one example with maps from the 1960s and 1990s, together with field work, revealed the degree of change that had taken place. In particular, there was a significant increase in forest – despite the kolkhoz system being targeted at in…
Malaria, poverty and medical treatment in the district of Agrigento (1830–1836)
1998
It is kown that the destruction of woods has been the reason of the beginning of"malaria". In the Middle Age there was a lot of forests in Sicily. In the province of Agrigento malaria was already kown especially in Cammarata in 1141; in the area of Burgic in 1172; in Licata in 1398 adin the south of Girgenti (Girgenti was the ancient name of Agrigento) in 1253. Huge expenses of water determined, between 1256 and 1379, the fight against malaria. In the XV and XV1 centuries the destruction of the Sicilian forests could be said systematically begun by the landowners, that had destined the land to the production of wheat. Then, the area of Agrigento was the place where the surviving vegetation …
Ptyctima (Acari, Oribatida) in various habitats in Finland
2010
The oribatid species of the taxon Ptyctima were studied in eight habitat types (four forests, three bogs, and one shore). Altogether 19 species were found. The highest number of species (15) was found in marsh forests in southern Finland, and the lowest number (3) in eutrophic fens in northern Finland. Atropacarus striculus was the most common and abundant species in Finland. It was found in each habitat explored, especially abundant on shores, in marsh forests, and pine bogs. Phthiracarus longulus, P. boresetosus, and Steganacarus carinatus occurred in abundance in coniferous forests, especially in the southern and central parts of the country, whereas Rhysotritia ardua was found there onl…
Study of the morphological affinity between two species of benthic foraminifera from restricted environments: Rosalina douvillei (Cushman, 1928) and …
2020
A biometric comparison is carried out on selected tests of the foraminiferal species Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermudez, 1935). The Rosalina douvillei specimens were recovered from the marginal marine Oligocene/Miocene site of Russingen (Mainz Basin, Germany), the lacustrine beds of the lower Miocene site of Bunol (Valencian Community, Spain) and the middle/ upper Miocene site of Fuendetodos (Aragon, Spain). The Trichohyalus aguayoi tests were collected in the current coastal lagoon of Torreblanca and recovered from Holocene cores sampled in the Peniscola marsh and in the coastal lagoon of l’Albufera de Valencia, all them in the Valencian Community (Spain)…
Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors
2016
The targeted optimization of the functional properties of porous materials includes the understanding of their transport properties and thus requires knowledge about the relationship between material synthesis, resulting in three-dimensional material morphology, and relevant transport properties. In this Perspective, we present our views and results on the characterization of microscopic disorder in functional porous materials, which are widely used today as fixed beds in adsorption, separation, and catalysis. This allows us to identify structural parameters that impact their mass transport properties and eventually their overall performance in technological operations. We address this comp…
Positron Studies of Subsurface Zone in Titanium Created in Sliding Wear
2014
Positron annihilation studies of the subsurface zone constituted during dry sliding in pure titanium are reported. A new type of defect depth profile in this zone, which is not an exponential decay usually reported for other metals and alloys, is observed. Two layers in the subsurface zone are present in this metal. In the layer adjacent to the worn surface, the characteristic plateau of the mean positron lifetime that extends to a depth of 60–70 μm was observed. Small vacancy clusters and dislocations were recognized in this layer. At deeper zone, the mean positron lifetime decreased exponentially in the manner typical for the other metals. In this zone, vacancy clusters increase in size a…
The effect of plasticity in crumpling of thin sheets
2008
Bridging the gap between theoretical and experimental work to understand the effect of plasticity on the crumpling of thin sheets into a small volume has proved difficult. A realistic numerical model now makes a distinction between elastic and elasto-plastic behaviour. Crumpling a thin sheet of material into a small volume requires energy for creating a network of deformations such as vertices and ridges1,2. Scaling properties of a single elastic vertex3,4,5 or ridge have been analysed theoretically6,7,8, and crumpling of a sheet by numerical simulations1,9,10. Real materials are however elasto-plastic11,12,13,14,15 and large local strains induce irreversible plastic deformations. Hence, a …
Nanoparticle-Directed Metal–Organic Framework/Porous Organic Polymer Monolithic Supports for Flow-Based Applications
2017
A two-step nanoparticle-directed route for the preparation of macroporous polymer monoliths for which the pore surface is covered with a metal–organic framework (MOF) coating has been developed to facilitate the use of MOFs in flow-based applications. The flow-through monolithic matrix was prepared in a column format from a polymerization mixture containing ZnO-nanoparticles. These nanoparticles embedded in the precursor monolith were converted to MOF coatings via the dissolution–precipitation equilibrium after filling the pores of the monolith with a solution of the organic linker. Pore surface coverage with the microporous zeolitic imidazolate framework ZIF-8 resulted in an increase in su…
Acoustic spectroscopy of aerogel precursors
2007
We investigate the acoustical properties of silica gels, which are precursors in the aerogel production process. These gels exhibit a strong “ringing gel” behavior, that is they emit a characteristic sound if one knocks against the container. We study this sound emission with a very simple spectroscopic technique and observe resonances which are characteristic for natural frequencies of a cylindrical body. From a fit of the experimental frequency positions to calculated values, we determine a sound velocity of c T = 4 m/s for a gel sample with porosity φ = 97.5%. This low sound velocity can only be interpreted as the transverse sound mode predicted by Biot’s theory for sound propagation in …