Optimal complexity of deployable compressive structures

The usual use of fractals involves self-similar geometrical objects to fill a space, where the self-similar iterations may continue ad infinitum. This is the first paper to propose the use of self-similar mechanical objects that fill an alloted space, while achieving an invariance property as the self-similar iterations continue (e.g. invariant strength). Moreover, for compressive loads, this paper shows how to achieve minimal mass and invariant strength from self-similar structures. The topology optimization procedure uses self-similar iteration until minimal mass is achieved, and this problem is completely solved, with global optimal solutions given in closed form. The optimal topology remains independent of the magnitude of the load. Mass is minimized subject to yield and/or buckling constraints. Formulas are also given to optimize the complexity of the structure, and the optimal complexity turns out to be finite. That is, a continuum is never the optimal structural for a compressive load under any constraints on the physical dimension (diameter). After each additional self-similar iteration, the number of bars and strings increase, but, for a certain choice of unit topology shown, the total mass of bars and strings decreases. For certain structures, the string mass monotonically increases with iteration, while the bar mass monotonically reduces, leading to minimal total mass in a finite number of iterations, and hence a finite optimal complexity for the structure. The number of iterations required to achieve minimal mass is given explicitly in closed form by a formula relating the chosen unit geometry and the material properties. It runs out that the optimal structures produced by our theory fall in the category of structures we call tensegrity. Hence our self-similar algorithms can generate tensegrity fractals.     

“Who polluted the Potomac?” The translation and implementation of a US environmental story in Brazilian and Turkish classrooms

In this study we examine how elementary teachers in Brazil and Turkey approached the translation and subsequent classroom implementation of an instructional activity that promotes environmental awareness through a combination of student role playing and teacher oral delivery of an environmental story about river pollution. A discourse analysis showed that translation into Portuguese was literal, an approach that fostered a classroom implementation that emphasized detached transmission of knowledge (the teacher frequently interrupted her delivery to provide textual, contextual and recontextualizing information to students). In contrast, translation into Turkish was free, that is, with many modifications that led to a decontextualized and detached text. Implementation of this text was focused on the creation of student involvement, being dominated by oral strategies such as religious analogies (heaven and hell), and parallel repetitions of statements of shared guilt. Based on these findings, it was concluded that neither translation promoted an equivalent form of environmental instruction (i.e., involved transmission of environmental knowledge). Furthermore, an argument is made that effective translation requires that original and translated curricula foster analogous levels of involvement (or detachment) as well as equivalent forms of classroom relationships and social roles (pragmatic equivalence).

Torrance Test of Creative Thinking: The question of its construct validity

Some cognitive dimensions are internationally considered by psychologists to describe and to assess creativity. For example, (Guilford, P. (1976). Creatividad y Educación. Buenos Aires. Ed. Paidos) and (Torrance, E. P. (1977). Discovery and nurturance of giftedness in the culturally different. Reston, VA: Council on Exceptional Children) suggested fluency, flexibility, originality and elaboration are the main cognitive processes used to define and assess creativity. However, data from several empirical studies did not confirm a factor structure in accordance with such cognitive functions, despite of the wide use of TTCT (Torrance Tests of Creative Thinking) in different countries. In this paper, we present new data collected in Spain and Portugal with TTCT. According to our data, those cognitive functions supposedly present on a subject's performance are not so strong as to explain the variance in scores. Elaboration factors assume some variance explanation, but the main factors are identified with the products in each subtest, suggesting the importance of format, content and demand on TTCT specific tasks. Consequently, we suggest some reflections to amplify the debate concerning the definition of creativity and its evaluation in psychology.     

Identification of a fungal community on gilded wood carved heritage

During restoration activities, a fungal reddish area was noted on a gilded wood carved ceiling decoration from a sacristy of a church in Aveiro, Portugal. The protocols used to identify the fungal community present in this wooden material included the classical culturing methods and a molecular biology protocol based on the ability of denaturing high performance liquid chromatography (DHPLC) to separate fungal DNA from several species. This last method complemented the results obtained with the traditional culturing method approach and the overall study revealed three fungal species: Serpula lacrymans (Wulfen) P. Karsten, Paecilomyces lilacinus (Thom) Samson and Penicillium chrysogenum Thom. This is, to the author's knowledge, the first documented case of S. lacrymans in Portuguese built cultural heritage. Despite the antifungal solution applied and the dryer environment recommended, the water activity (Aw) levels recorded on location are still dangerously high and may allow fungal regrowth. Periodic inspections were advised.