Search results for " sphere"
showing 10 items of 404 documents
Determination of an empirical law of aluminium and magnesium alloys absorption coefficient during Nd :YAG laser interaction
2007
International audience; Welding laser modelling requires knowledge about relative changes of many thermo-physical parameters involved in the interaction. The absorptivity of the material is one of the most important. In this study, experimental measurements of absorptivity with an integrating sphere on two alloys (aluminium and magnesium) were made. These results were compared with an analytical calculation that takes into account the trapping of the beam by multiple reflections inside the keyhole. Based on a statistical method, an empirical law is proposed connecting absorptivity with the peak power of the laser and the duration of interaction. During the interaction, two distinct phenomen…
Atomic structure of manganese-doped yttrium orthoaluminate
2018
Abstract Using hybrid exchange-correlation functional within density functional theory we have performed first-principle total energy calculations of Mn-doped yttrium orthoaluminate (YAlO3). Its equilibrium atomic structure has been predicted through optimization of coordinates of all atoms using a supercell approach. In our research both Mn3+ and Mn2+ ions have been substituted for the host alumina atom at orthorhombic Pbnm unit cell of YAlO3. F-center has been implemented as charge-compensating defect in case, when Mn2+ dopant is under study. In this study we thoroughly analyze the atomic displacements in seven nearest to Mn ion coordination spheres. Insertion of isoelectronic substitutio…
First M87 Event Horizon Telescope Results. I. the Shadow of the Supermassive Black Hole
2019
When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux rati…
Leaf-Level Spectral Fluorescence Measurements : Comparing Methodologies for Broadleaves and Needles
2019
Successful measurements of chlorophyll fluorescence (ChlF) spectral properties (typically in the wavelength range of 650–850 nm) across plant species, environmental conditions, and stress levels are a first step towards establishing a quantitative link between solar-induced chlorophyll fluorescence (SIF), which can only be measured at discrete ChlF spectral bands, and photosynthetic functionality. Despite its importance and significance, the various methodologies for the estimation of leaf-level ChlF spectral properties have not yet been compared, especially when applied to leaves with complex morphology, such as needles. Here we present, to the best of our knowledge, a first comparison of …
The effect of a membrane-mimicking environment on the interactions of Cu2+ with an amyloidogenic fragment of chicken prion protein
2017
Prion proteins (PrP) from different species have the ability to tightly bind Cu2+ ions. Copper coordination sites are located in the disordered and flexible N-terminal region which contains several His anchoring sites. Among them, two His residues are found in the so called amyloidogenic PrP region which is believed to play a key role in the process leading to oligomer and fibril formation. Both chicken and human amyloidogenic regions have a hydrophobic C-terminal region rich in Ala and Val amino acids. Recent findings revealed that this domain undergoes random coil to α-helix structuring upon interaction with membrane models. This interaction might strongly impact metal binding abilities e…
Invisibilization and Silencing as an Ethical and Sociological Challenge
2017
AbstractExcluded and/or marginalized social groups frequently face problems involving representation in the public sphere. Moreover, the very notion of exclusion typically refers to communicatively or discursively produced mechanisms of being considered irrelevant in public processes of communication. Exclusion and marginalization, understood as processes of silencing or invisibilizing social groups, are particularly serious in cases involving social suffering, i.e. socially produced suffering and/or suffering that can be eliminated or alleviated socially. Making silence heard, giving voice to the silenced and bringing the invisibilized back into the public domain are therefore fundamental …
Sociología, Derecho y desigualdades sociales. Una propuesta de docencia universitaria crítica
2019
Fil: Di Nella, Dino. Universidad Nacional de Río Negro. Río Negro, Argentina. Fil: Almeda, Elisabet. Universidad de Barcelona. Catalunya, España. Fil: Camps Calvet, Clara. Universidad de Barcelona. Catalunya, España. Fil: Giordana, Patricia. Universidad Nacional de Río Negro. Río Negro, Argentina. Fil: Loggiacco, Camila. Universidad Nacional de Río Negro. Río Negro, Argentina. Fil: D'Alfonso, Luis. Universidad Nacional de Río Negro. Río Negro, Argentina. Critic education in human rights and social inequalities must be able to capture holistic and mutidmiensional sphere that Human Rights requires. This study introduces the basis in which critic university teaching proposal is carectarized by…
Guía para la incorporación de la perspectiva de género en la docencia en Sociología, Economía y Ciencias Políticas
2019
Sociology has constructed a male worldview that entails a biased interpretation of social reality. For its part, the traditional economy has made invisible the dependence of the commercial sphere of the domestic sphere. And in the field of political science, we also find many gender biases in basic concepts such as justice, equality or citizenship. This article, based on the work done by the authors in the Guia per a una docència universitària amb perspectiva de gènere de Sociologia, Economia i Ciència Política, offers some proposals, teaching resources and consultation tools to introduce the gender perspective in teaching, knowledge transfer and research in these disciplines.
Radical sex role ideology and the Finnish gender role movement in the late 1960s
2022
An active discussion of gender roles and the need to renegotiate them took place in the late 1960s in Finland. While previous studies have associated this ‘sex role debate’ with the independent civic organisation Association 9, this article focuses on the wider gender role movement. The article analyses the interplay and differences among the Finnish Women’s Democratic League, the Committee for Women’s Status, and Association 9’s grassroots activism between 1965 and 1970. It demonstrates that similar ideas about sex roles were presented simultaneously in two public spheres: the dominant public, where the ideas were promoted by Association 9, and the people’s democratic counterpublic, which …
Description of hard-sphere crystals and crystal-fluid interfaces: a comparison between density functional approaches and a phase-field crystal model.
2012
In materials science the phase field crystal approach has become popular to model crystallization processes. Phase field crystal models are in essence Landau-Ginzburg-type models, which should be derivable from the underlying microscopic description of the system in question. We present a study on classical density functional theory in three stages of approximation leading to a specific phase field crystal model, and we discuss the limits of applicability of the models that result from these approximations. As a test system we have chosen the three--dimensional suspension of monodisperse hard spheres. The levels of density functional theory that we discuss are fundamental measure theory, a …