Habitat filtering determines spatial variation of macroinvertebrate community traits in northern headwater streams

Although our knowledge of the spatial distribution of stream organisms has been increasing rapidly in the last decades, there is still little consensus about trait-based variability of macroinvertebrate communities within and between catchments in near-pristine systems. Our aim was to examine the taxonomic and trait based stability vs. variability of stream macroinvertebrates in three high-latitude catchments in Finland. The collected taxa were assigned to unique trait combinations (UTCs) using biological traits. We found that only a single or a highly limited number of taxa formed a single UTC, suggesting a low degree of redundancy. Our analyses revealed significant differences in the environmental conditions of the streams among the three catchments. Linear models, rarefaction curves and beta-diversity measures showed that the catchments differed in both alpha and beta diversity. Taxon- and trait-based multivariate analyses also indicated that the three catchments were significantly different in terms of macroinvertebrate communities. All these findings suggest that habitat filtering, i.e., environmental differences among catchments, determines the variability of macroinvertebrate communities, thereby contributing to the significant biological differences among the catchments. The main implications of our study is that the sensitivity of trait-based analyses to natural environmental variation should be carefully incorporated in the assessment of environmental degradation, and that further studies are needed for a deeper understanding of trait-based community patterns across near-pristine streams

Measurement of the CP properties of Higgs boson interactions with τ-leptons with the ATLAS detector

A study of the charge conjugation and parity (CP ) properties of the interaction between the Higgs boson and τ -leptons is presented. The study is based on a measurement of CP -sensitive angular observables defined by the visible decay products of τ -leptons produced in Higgs boson decays. The analysis uses 139 fb−1 of proton–proton collision data recorded at a centre-of-mass energy of √s=13 TeV with the ATLAS detector at the Large Hadron Collider. Contributions from CP -violating interactions between the Higgs boson and τ -leptons are described by a single mixing angle parameter ϕτ in the generalised Yukawa interaction. Without constraining the H→ττ signal strength to its expected value under the Standard Model hypothesis, the mixing angle ϕτ is measured to be 9∘±16∘ , with an expected value of 0∘±28∘ at the 68% confidence level. The pure CP -odd hypothesis is disfavoured at a level of 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model

Marcatili's extended approach: comparison to semi-vectorial methods applied to pedestal waveguide design

International audienc

Qualidade das sementes de aveia-preta de acordo com a pigmentação.

RESUMO: Em lotes comerciais de sementes de aveia-preta, é comum a presença de sementes sem pigmentação, principalmente quando as mesmas são submetidas a condições de estresse durante a fase de maturação. O objetivo deste trabalho foi comparar a qualidade das sementes de aveia-preta de acordo com sua pigmentação. Foram utilizados 12 lotes comerciais de sementes, produzidas na safra 2012/2012, no Rio Grande do Sul. As sementes, dentro de cada lote, foram separadas em pigmentadas e não pigmentadas. Efetuou-se o tratamento para superação da dormência, além da caracterização das sementes pelos testes: matéria de mil sementes; germinação; primeira contagem; matéria seca de plântulas; comprimento de plântulas, e índice de velocidade de germinação. Não há relação entre o grau de dormência e a pigmentação em sementes de aveia-preta. Sementes de aveia-preta sem pigmentação possuem menor matéria de mil sementes e qualidade fisiológica inferior em relação às pigmentadas. ABSTRACT: Seeds without pigmentation are commonly found in commercial lots of black oat seeds, especially when they are produced under stress conditions during their maturation process. In this study, we aimed to compare oat seed quality according to pigmentation. Twelve lots of black oat seeds from the 2012/2012 crop in the state of Rio Grande do Sul were used. Each seed lot was separated in two samples according to their pigmentation: pigmented and non-pigmented. Subsequently, treatment to overcome seed dormancy was performed. To evaluate seed quality, seed samples were submitted to the following tests and determinations: weight of thousand seeds, germination, first count of germination, seedling dry mass, seedling length, and germination speed index. According to the results obtained, there is no relation between seed pigmentation and seed dormancy. Black oat seeds without pigmentation present lower weight of thousand seeds and lower physiological quality compared with pigmented seeds.201

Orthorhombic vs. hexagonal epitaxial SrIrO3 thin films: Structural stability and related electrical transport properties

Metastable orthorhombic SrIrO3 (SIO) is an arch-type spin-orbit coupled material. We demonstrate here a controlled growth of relatively thick (200 nm) SIO films that transform from bulk ``6H-type'' structure with monoclinic distortion to an orthorhombic lattice by controlling growth temperature. Extensive studies based on high-resolution X-ray diffraction and transmission electron microscopy infer a two distinct structural phases of SIO. Electrical transport reveals a weak temperature-dependent semi-metallic character for both phases. However, the temperature-dependent Hall-coefficient for the orthorhombic SIO exhibits a prominent sign change, suggesting a multiband character in the vicinity of E-F. Our findings thus unravel the subtle structure-property relation in SIO epitaxial thin films. Copyright (C) EPLA, 201