1,721,422 research outputs found
Pheasant (Phasianus colchicus) hens of different origin. Dispersion and habitat use after release
No full textBecause of the importance of pheasants as a game bird species in many European Countries, information on the success of the restocking programs is interesting for evaluation. For this reason the survival, behaviour and habitat selection of 10 wild translocated and 20 released ring-necked pheasants (10 offspring of wild captured and 10 from the farmed strain, both farm-reared) was studied using radio-telemetry during March-August (fixes were grouped in 3 categorized periods: March 2 - April 18; April 19 - May 28; May 29 - August 16). All the captive reared pheasants were reared according to the new disciplinary rules set forth by the Toscana region for the production of pheasants destined to be released in the wild as part of a game repopulation program. The study was carried out in a hilly area of the Tuscany characterised by 18.1% woodland (core: 1654895E, 4850468N). Results showed that live weights were higher in the farm-reared pheasants (either directly captured or offspring of the captured, P<0.05). The tarsus length statistically differed between the farmed offspring of the captured pheasants and the farm strain (P<0.05). The survival rates and breeding success of the surviving subjects were very high and did not differ between groups (survival rates: 50.0%, 70.0% and 80.0%, and breeding success: 60.0%, 28.6% and 50.0%, for the captive-reared offspring of captured wild pheasants, the captive-reared farm pheasants and the captured wild pheasants, respectively). The dispersion increased with time in the wild translocated pheasants (576 m, 889 m and 1209 m) while the offspring of the captured wild pheasants and the farm strain remained in the vicinity of the releasing site. The wild pheasants showed an increasing distance from the country houses, contrary to the offspring of captured wild pheasants and the farm strain. Artificial feeding stations were better used by the farm-reared pheasants, which remained in the vicinity of the artificial feeding points. The results of our study showed that pheasants, reared according to the disciplinary rules stated for the production of pheasants for wildlife reproduction programs, although more expensive, can guarantee the genetic identity with the resident populations and are able to provide good survival rates and breeding success of the released pheasants, of course when restocking is carried out in areas suitable for pheasant wildlife
Migrating Bedforms Generated by Solitary Waves
No full textWe present experimental results on the formation of streamwise asymmetric, migrating bedforms resulting from the transition of successive surface solitary waves (SSW) interacting with an initially flat sandy bottom. We analyze seven cases, with differing ratios between SSW height and water depth. For each experiment, we generated 400 SSWs having the same features, investigating their effects on the bed, in terms of near-bed velocity and erosional patterns. Our work proves that SSWs can generate asymmetric bedforms, similar in shape to dunes. The triggering process occurs in the region where the reverse flow induced by bottom boundary layer separation produces local erosion. The action of successive SSWs over the newly formed discontinuities gives rise to bedforms. Differently from steady flows, dune load decreases for larger wave-induced bottom shear stress
Synergy of satellite remote sensing and numerical ocean modelling for coastal geomorphology diagnosis
No full textSediment dynamics is the primary driver of the evolution of the coastal geomorphology and of the underwater shelf clinoforms. In this paper, we focus on mesoscale and sub-mesoscale processes, such as coastal currents and river plumes, and how they shape the sediment dynamics at regional or basin spatial scales. A new methodology is developed that combines observational data with numerical modelling: the aim is to pair satellite measurements of suspended sediment with velocity fields from numerical oceanographic models, to obtain an estimation of the sediment flux. A numerical divergence of this flux is then computed. The divergence field thus obtained shows how the aforementioned mesoscale processes distribute the sediments. The approach was applied and discussed on the Adriatic Sea, for the winter of 2012, using data provided by the ESA Coastcolour project and the output of a run of the MIT General Circulation Model
A simple three layerr model for the behaviour of a turbidity current as a function of the Richardson number: sedimentological implications.
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Sedimentology and physical stratigraphy of the Messinian Laga turbidite complex (central Apennines, Italy)
No full textA three layers model for the turbidity current: an inverse problem to infer the ignition condition from turbidite deposits
No full textA generalized Stefan model accounting for system memory and non-locality
Full text linkThe Stefan problem, involving the tracking of an evolving phase-change front, is the prototypical example of a moving boundary problem. In basic one- dimensional problems it is well known that the front advances as the square root of time. When memory or non-locality are introduced into the system however, this classic signal may be anomalous; replaced by a power-law advance with a time exponent that differs from n = 1/2. Up to now memory treatments in Stefan problem models have only been able to reproduce sub-diffusive front movements with exponents n 1/2. In the present paper, using a generalized Caputo fractional derivative operator, we introduce new memory and non-local treatment for Stefan problems. On considering a limit case Stefan problem, related to the melting problem, we are able to show that, this gen- eral treatment can not only produce arbitrary power-law in time predictions for the front movement but, in the case of memory treatments, can also produce non-power-law anomalous behaviors. Further, also in the context of the limit problem, we are able to establish an equivalence between non-locality and a space varying conductivity and memory and a time varying conductivity
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