Studying with Bream

Editor's note: letter to the Vórtex dossier in honor of Julian Bream

Studying with Bream

Editor's note: letter to the Vórtex dossier in honor of Julian Bream

Understanding Metacognitive Failure

This paper reports on a study that investigated patterns of collaborative metacognitive activity in senior secondary school classrooms. Although peers working together on mathematical tasks may enjoy the metacognitive benefits of being able to monitor and regulate each other’s thinking, collaboration does not guarantee that they will achieve a mathematically productive outcome. The notion of metacognitive "red flags", or warning signals that problem solving has gone astray, is developed in order to identify three possible scenarios for metacognitive failure. These scenarios, described by the metaphors of blindness, vandalism, and mirage, are illustrated via analysis of videotaped lesson transcripts obtained from a secondary school mathematics classroom. The results provide insights into the interactive constitution of metacognitive activity during small group work, and suggest implications for teachers concerning the fostering of communication and problem solving within a classroom culture of inquiry

Tctex2: A Sperm Tail Surface Protein Mapping to the t-Complex

AbstractTransmission ratio distortion (TRD) in mouse t-haplotypes remains the most significant example of meiotic drive in vertebrates. While the underlying mechanism that fuels it is still mysterious, TRD is clearly a complex multigene phenomenon. The characterization of Tctex2 (t-complex testis expressed 2) shows it to be one of several candidates for involvement in TRD. Tctex2 maps to the t-complex and encodes a membrane-associated protein found exclusively on the sperm tail. The t-haplotype form of Tctex2 is aberrant in both the level of its expression and its primary amino acid sequence, but is nonetheless translated and transported to its normal location. The multiple amino acid changes in the t-form make it extremely unlikely that it can function normally and, since it is found on sperm tails, suggest that it may actively interfere with the development of normal gamete function in males. The possible role of Tctex2 in t -complex transmission ratio distortion and sterility is discussed

Algumas Reflexões Sobre Ritmo - Prólogo do livro “Rhythmic Mastery” de Alice Artzt

Quando pensamos em encontrar tesouros, pensamos em uma longa jornada onde no fim encontram-se coisas valiosas escondidas e inatingíveis. Mas, às vezes, os tesouros estão bem na nossa frente, no primeiro passo da jornada. Esse é o caso quando lemos o livro "Rhythmic Mastery" de Alice Artztz. Em seu livro, encontramos um mapa do tesouro na terceira página, a página de agradecimentos. Nossa guia, Alice Artzt, nos instrui: "Gostaria de agradecer a Sergio Abreu por seus extensos conselhos durante a escrita deste livro e por sua inestimável colaboração no Prólogo." Assim temos o prólogo "Algumas Reflexões sobre o Ritmo", escrito por Alice Artztz e Sergio Abreu. Ali está o nosso tesouro, logo no início deste grande livro. E tal tesouro cultural deve ser trazido à luz e compartilhado. Essa é a razão de traduzir O prólogo para o português

Non-destructive characterization of internal surfaces in LPBF Inconel 718 channel

The presented non-destructive computed tomography analysis method provides a comprehensive quantitative characterization of internal surfaces before and after treatment and optimizes etching methods

Non-destructive characterization of internal surfaces in Laser Powder Bed Fused Inconel 718 channels prior and after post-treatment

The effect of surface finishing treatments for inner surfaces of additvely manufactured Inconel 718 specimens were analyzed using X-ray computed tomography (CT). The tube-shaped specimens were built by Laser Powder Bed Fusion (LPBF) at different build orientations and the inner surface characteristics such as roundness, equivalent diameter, 3D curvature distribution and distance to nominal surface as radial roughness for internal channels, both in the primary as built condition and after the subsequent treatment, were evaluated

Micromechanical behavior of annealed Ti-6Al-4V produced by Laser Powder Bed Fusion

the micromechanical behavior of an annealed ti-6al-4V material produced by laser Powder Bed Fusion was characterized by means of in-situ synchrotron X-ray diffraction during a tensile test. the lattice strain evolution was obtained parallel and transversal to the loading direction. the elastic constants were determined and compared with the conventionally manufactured alloy. in the plastic regime, a lower plastic anisotropy exhibited by the lattice planes was observed along the load axis (parallel to the building direction) than in the transverse direction. also, the load transfer from α to β phase was observed, increasing global ductility of the material. The material seems to accumulate a significant amount of intergranular strain in the transverse direction

An assessment of subsurface residual stresses analysis in SLM Ti 6Al 4V

Ti-6Al-4V bridges were additively fabricated by selective laser melting (SLM) under different scanning speed conditions, to compare the effect of process energy density on the residual stress state. Subsurface lattice strain characterization was conducted by means of synchrotron diffraction in energy dispersive mode. High tensile strain gradients were found at the frontal surface for samples in an as-built condition. The geometry of the samples promotes increasing strains towards the pillar of the bridges. We observed that the higher the laser energy density during fabrication, the lower the lattice strains. A relief of lattice strains takes place after heat treatment