Defining the importance of landscape metrics for large branchiopod biodiversity and conservation: the case of the Iberian Peninsula and Balearic Islands

The deficiency in the distributional data of invertebrate taxa is one of the major impediments acting on the bias towards the low awareness of its conservation status. The present study sets a basic framework to understand the large branchiopods distribution in the Iberian Peninsula and Balearic Islands. Since the extensive surveys performed in the late 1980s, no more studies existed updating the information for the whole studied area. The present study fills the gap, gathering together all available information on large branchiopods distribution since 1995, and analysing the effect of human population density and several landscape characteristics on their distribution, taking into consideration different spatial scales (100 m, 1 km and 10 km). In overall, 28 large branchiopod taxa (17 anostracans, 7 notostracans and 4 spinicaudatans) are known to occur in the area. Approximately 30% of the sites hosted multiple species, with a maximum of 6 species. Significant positive co-occurring species pairs were found clustered together, forming 4 different associations of large branchiopod species. In general, species clustered in the same group showed similar responses to analysed landscape characteristics, usually showing a better fit at higher spatial scales.Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq [401045/2014-5]Spanish Ministry of Education, Culture and Sport [FPU014/06783]info:eu-repo/semantics/publishedVersio

Deformation mechanisms of a commercial titanium alloy Ti6Al4V as a function of strain rate and initial texture

This paper presents the results of an experimental study on the mechanical behaviour of a commercial titanium alloy Ti6Al4V. One of the aims was to characterize the influence of adiabatic shear banding during compression at room temperature and at different strain rates. Cylindrical specimens were fabricated from an extruded bar in the mill annealed condition. For the lower strain rates, these specimens were deformed in uni-axial compression at room temperature by means of a servo-hydraulical testing machine. A Split Hopkinson Pressure Bar was used for the higher strain rate domain. The compression axis was taken both parallel and perpendicular to the extrusion axis of the as received bar, in order to take into account the contribution of the initial crystallographic texture. The microstructural evolution was carried out using optical and electron scanning microscopy, more particularly for determining the onset of adiabatic shear banding. One of the major observations is that adiabatic shear banding is starting at much lower strain rates as could be found in the current literature, and this as a function of the compression axis orientation. These results have an important influence on the ballistic behaviour

Deformation mechanisms of a commercial titanium alloy Ti6Al4V as a function of strain rate and initial texture

This paper presents the results of an experimental study on the mechanical behaviour of a commercial titanium alloy Ti6Al4V One of the aims was to characterize the influence of adiabatic shear banding during compression at room temperature and at different strain rates. Cylindrical specimens were fabricated from an extruded bar in the mill annealed condition. For the lower strain rates, these specimens were deformed in uni-axial compression at room temperature by means of a servo-hydraulical testing machine. A Split Hopkinson Pressure Bar was used for the higher strain rate domain. The compression axis was taken both parallel and perpendicular to the extrusion axis of the as received bar, in order to take into account the contribution of the initial crystallographic texture. The microstructural evolution was carried out using optical and electron scanning microscopy, more particularly for determining the onset of adiabatic shear banding. One of the major observations is that adiabatic shear banding is starting at much lower strain rates as could be found in the current literature, and this as a function of the compression axis orientation. These results have an important influence on the ballistic behaviour

Constitutive equations of a ballistic steel alloy as a function of temperature

In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB). The impact behavior was investigated for strain rates ranging from 1000 to 2500 s−1, and temperatures in the range from − 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds) has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles) was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities

Constitutive equations of a ballistic steel alloy as a function of temperature

In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB). The impact behavior was investigated for strain rates ranging from 1000 to 2500 s−1, and temperatures in the range from − 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds) has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles) was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities

Richness of Dendrocephalus (Branchiopoda, Anostraca) in Brazil with the description of two new species

International audienceWe present an overview of the morphological diversity and geographical distribution of the anostracan genus Dendrocephalus Daday, 1908, and describe two new species: D. aranai sp. nov. from Jequitinhonha in the state of Minas Gerais and D. xikrini sp. nov. from the Carajás Mountains (Serra dos Carajás) in the state of Pará. These species have important similarities to D. goiasensis Rabet & Thiéry, 1996 and D. thieryi Rabet, 2006, respectively, but differ from them and each other through a combination of characters that are essentially unique to the endopods, and frontal appendage branch 2A and branch 2D. We also partly redescribe D. carajaensis Rogers, Gomes & Vieira, 2012, which shows a particular intra-populational variability in branch 2A and 2D III of the frontal appendage, a type of polymorphism that was also recently observed in D. orientalis Rabet & Thiéry, 1996 and which must now be taken into account in taxonomy. In terms of the distribution of species of Dendrocephalus in Brazil, we suggest that several other species are probably present in the Amazonian, Cerrado and Pantanal Biomes, which remain largely unexplored. A new taxonomic key for the identification of males of the Brazilian species is provided