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Some errors in the learning of algebra suggest that students might have difficulties giving meaning to algebraic symbolism. In this paper, we use problem posing to analyze the students’ capacity to assign meaning to algebraic symbolism and the difficulties that students encounter in this process, depending on the characteristics of the algebraic statements given. We designed a written questionnaire composed of eight closed algebraic statements expressed symbolically, which was administered to 55 students who had finished their compulsory education and who had some previous experience in problem-posing. In our analysis of the data, we examine both syntactic and semantic structures of the problem posed. We note that in most cases students posed problems with syntactic structures different to those given. They did not include computations within variables, and changed the kinds of relationships connecting variables. Students easily posed problems for statements with additive structures. Other differences in the type of problems posed depend on the characteristics of the given statements. [ABSTRACT FROM AUTHOR]

The cleft palate presented by transforming growth factor-β3 (Tgf-β3) null mutant mice is caused by altered palatal shelf adhesion, cell proliferation, epithelial-to-mesenchymal transformation and cell death. The expression of epidermal growth factor (EGF), transforming growth factor-β1 (Tgf-β1) and muscle segment homeobox-1 (Msx-1) is modified in the palates of these knockout mice, and the cell proliferation defect is caused by the change in EGF expression. In this study, we aimed to determine whether this change in EGF expression has any effect on the other mechanisms altered in Tgf-β3 knockout mouse palates. We tested the effect of inhibiting EGF activity in vitro in the knockout palates via the addition of Tyrphostin AG 1478. We also investigated possible interactions between EGF, Tgf-β1 and Msx-1 in Tgf-β3 null mouse palate cultures. The results show that the inhibition of EGF activity in Tgf-β3 null mouse palate cultures improves palatal shelf adhesion and fusion, with a particular effect on cell death, and restores the normal distribution pattern of Msx-1 in the palatal mesenchyme. Inhibition of TGF-β1 does not affect either EGF or Msx-1 expression. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Folic acid (FA) is essential for numerous bodily functions. Its decrease during pregnancy has been associated with an increased risk of congenital malformations in the progeny. The relationship between FA deficiency and the appearance of cleft palate (CP) is controversial, and little information exists on a possible effect of FA on palate development. We investigated the effect of a 2-8 weeks' induced FA deficiency in female mice on the development of CP in their progeny as well as the mechanisms leading to palatal fusion, i.e. cell proliferation, cell death, and palatal-shelf adhesion and fusion. We showed that an 8 weeks' maternal FA deficiency caused complete CP in the fetuses although a 2 weeks' maternal FA deficiency was enough to alter all the mechanisms analyzed. Since transforming growth factor-β3 (TGF-β3) is crucial for palatal fusion and since most of the mechanisms impaired by FA deficiency were also observed in the palates of Tgf-β3null mutant mice, we investigated the presence of TGF-β3 mRNA, its protein and phospho-SMAD2 in FA-deficient (FAD) mouse palates. Our results evidenced a large reduction in Tgf-β3 expression in palates of embryos of dams fed an FAD diet for 8 weeks; Tgf-β3 expression was less reduced in palates of embryos of dams fed an FAD diet for 2 weeks. Addition of TGF-β3 to palatal-shelf cultures of embryos of dams fed an FAD diet for 2 weeks normalized all the altered mechanisms. Thus, an insufficient folate status may be a risk factor for the development of CP in mice, and exogenous TGF-β3 compensates this deficit in vitro. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In this article we introduce and study the first cohomology categorical group ℋ1(𝔾,𝔸) of a categorical group 𝔾 with coefficients in a braided categorical group 𝔸 provided of a coherent 𝔾-action. The fundamental exact sequence connecting ℋ0 and ℋ1 in this context is then established. [ABSTRACT FROM AUTHOR]