Refus de soin

National audienc

Bioclimatology, structure, and conservation perspectives of Quercus pyrenaica, Acer opalus subsp. Granatensis, and Corylus avellana deciduous forests on Mediterranean bioclimate in the South-Central part of the Iberian Peninsula

The plant variability in the southern Iberian Peninsula consists of around 3500 different taxa due to its high bioclimatic, geographic, and geological diversity. The deciduous forests in the southern Iberian Peninsula are located in regions with topographies and specific bioclimatic conditions that allow for the survival of taxa that are typical of cooler and wetter bioclimatic regions and therefore represent the relict evidence of colder and more humid paleoclimatic conditions. The floristic composition of 421 samples of deciduous forests in the south-central part of the Iberian Peninsula were analyzed. The ecological importance index (IVI) was calculated, where the most important tree species were Quercuspyrenaica, Aceropalus subsp. Granatensis, and Corylusavellana. These species are uncommon in the south-central part of the Iberian Peninsula, forming forests of little extension. An analysis of the vertical distribution of the species (stratum) shows that the majority of the species of stratum 3 (hemicriptophics, camephytes, geophites, and nanophanerophytes) are characteristic of deciduous forests, and their presence is positively correlated with high values of bioclimatic variables related to humidity and presence of water in the soil (nemoral environments), while they are negatively correlated with high values of bioclimatic variables related to high temperatures, evapotranspiration, and aridity. This work demonstrates that several characteristic deciduous forest taxa are more vulnerable to disappearance due to the loss of their nemoral conditions caused by gaps in the tree or shrub canopy. These gaps lead to an increase in evapotranspiration, excess insolation, and a consequent loss of water and humidity in the microclimatic conditions.info:eu-repo/semantics/publishedVersio

Aplicação da termometria por infravermelho a irrigação do feijoeiro (Phaseolus vulgaris L.): parâmetros fisiológicos.

Avaliou-se no campo a resposta de plantas de feijao (Phaseolus vulgaris L.) cv Carioca submetidas a quatro regimes de irrigacao, visando adotar um indicador fisiologico que permitisse determinar o momento de se efetuar a irrigacao, tanto na fase vegetativa quanto na reprodutiva. Registraram-se significativas relacoes entre os decrescimos do potencial hidrico foliar e os acrescimos na resistencia estomatica ao longo do dia, e desta com os aumentos na temperatura do dossel, que foram maiores nas plantas sob deficiencia hidrica mais acentuada. Os maiores diferenciais de temperatura do dossel foram observados entre o controle irrigado e o tratamento mais seco. Tambem foram registrados para cada tratamento, diferenciais de temperatura do dossel em relacao a temperatura do ar, obtendo-se diferenciais positivos apenas nas plantas sob menor frequencia de irrigacao na condicao maxima de tensao de agua no solo. Os resultados indicam que o diferencial de temperatura do dossel entre uma parcela de plantas bem irrigadas e outra submetida ao estresse hidrico foi o parametro fisiologico mais apropriado para monitorar a irrigacao

Interplay of magnetic and structural transitions in Fe-based pnictide superconductors

The interplay between the structural and magnetic phase transitions occurring in the Fe-based pnictide superconductors is studied within a Ginzburg-Landau approach. We show that the magnetoelastic coupling between the corresponding order parameters is behind the salient features observed in the phase diagram of these systems. This naturally explains the coincidence of transition temperatures observed in some cases as well as the character (first or second-order) of the transitions. We also show that magnetoelastic coupling is the key ingredient determining the collinearity of the magnetic ordering, and we propose an experimental criterion to distinguish between a pure elastic from a spin-nematic-driven structural transition.Comment: 5 pages, 3 figures. v2: Fig. 1 improved, references added

Ruddlesden-Popper and perovskite phases as a material platform for altermagnetism

The subclass of collinear antiferromagnets where spin Kramers degeneracy is broken -- so that they can display ferromagnetic-like properties -- stimulates a new perspective in magnetism. However, the material base for these so-called altermagnets is still relatively limited. We show that Ruddlesden-Popper and perovskite phases generically host altermagnetic materials. In particular, we analyze prototypical nickel-based systems via first-principles calculations and identify additional materials from their crystal structure and magnetic orders. These materials span both insulating/semiconducting and metallic conduction types and the computed values of the nonrelativistic spin splittings reach 250~meV. Our analysis also indicates some formal inconsistencies that may appear within the traditional classification of magnetically ordered materials, which can easily be resolved from the altermagnetic perspective. In addition, we indicate the possibility of having altermagnetic behavior in systems beyond collinear antiferromagnets with perfectly compensated magnetization.Comment: 7 pages, 5 figures, 1 tabl