Relaciones métricas en los triángulos : Matemáticas.

Estudio acerca de las relaciones métricas entre los triángulos, sobre la base de lecciones explicadas a los alumnos de tercer curso del Instituto Ramiro de Maeztu, en la Cátedra de Metodología y Didáctica de la Matemática. Algunas de las relaciones que se explican mediante diagramas y operaciones matemáticas son: si sobre los lados de un triángulo escaleno construimos triángulos semejantes al dado, el triángulo construido sobre el lado mayor es mayor, igual o menor, que la suma de los otros dos, según que el triángulo dado sea obtusángulo, rectángulo u acutángulo. También se estudia el teorema de la altura: en un triángulo rectángulo, la altura relativa de la hipotenusa es medio proporcional entre los dos segmentos en que descompone a ésta; o el teorema de Pitágoras, que señala que el cuadrado construido sobre la hipotenusa es equivalente a la suma de los cuadrados construidos sobre los catetos. Por último se hace referencia a las aplicaciones de las relaciones métricas estudiadas en la resolución de ejercicios.

Students reflections on pedagogical translation in Spanish as a foreign language

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Internal structure of chlorosomes from brown-colored Chlorobium species and the role of carotenoids in their assembly

Chlorosomes are the main light harvesting complexes of green photosynthetic bacteria. Recently, a lamellar model was proposed for the arrangement of pigment aggregates in Chlorobium tepidum chlorosomes, which contain bacteriochlorophyll (BChl) c as the main pigment. Here we demonstrate that the lamellar organization is also found in chlorosomes from two brown-colored species (Chl. phaeovibrioides and Chl. phaeobacteroides) containing BChl e as the main pigment. This suggests that the lamellar model is universal among green sulfur bacteria. In contrast to green-colored Chl. tepidum, chlorosomes from the brown-colored species often contain domains of lamellar aggregates that may help them to survive in extremely low light conditions. We suggest that carotenoids are localized between the lamellar planes and drive lamellar assembly by augmenting hydrophobic interactions. A model for chlorosome assembly, which accounts for the role of carotenoids and secondary BChl homologs, is presented

O modo de Ensino mútuo na formação dos mestres de primeiras letras : uma experiência pedagógica no Portugal Oitocentista

No presente artigo, procede-se à análise sumária da problemática relativa à habilitação dos professores de ler, escrever e contar, em Portugal, na primeira metade do século XIX. Esta formação destinava-se a adestrar os mestres do ensino oficial na aplicação do modo de ensino mútuo. A primeira Escola Normal, localizada em Lisboa, abre em 1824 mas, só após 1836, entram em funcionamento escolas congéneres um pouco por todo o país. Para facilitar a compreensão desta temática, começa-se por fazer uma breve referência introdutória ao aparecimento deste “novo” ensino na cultura escolar europeia e aos seus princípios orientadores.

The southern sotho speech identification/discrimination test construction

This paper contains a speech discrimination test in Southern Sotho language (an African language spoken in Southern Africa).

The interannual variability of energy transports within and over the Atlantic Ocean in a coupled climate model

To gain a new perspective on the interaction of the Atlantic Ocean and the atmosphere, the relationship between the atmospheric and oceanic meridional energy transports is studied in a version of HadCM3, the U.K. Hadley Centre's coupled climate model. The correlation structure of the energy transports in the atmosphere and Atlantic Ocean as a function of latitude, and the cross correlation between the two systems are analyzed. The processes that give rise to the correlations are then elucidated using regression analyses. In northern midlatitudes, the interannual variability of the Atlantic Ocean energy transport is dominated by Ekman processes. Anticorrelated zonal winds in the subtropics and midlatitudes, particularly associated with the North Atlantic Oscillation (NAO), drive anticorrelated meridional Ekman transports. Variability in the atmospheric energy transport is associated with changes in the stationary waves, but is only weakly related to the NAO. Nevertheless, atmospheric driving of the oceanic Ekman transports is responsible for a bipolar pattern in the correlation between the atmosphere and Atlantic Ocean energy transports. In the Tropics, the interannual variability of the Atlantic Ocean energy transport is dominated by an adjustment of the tropical ocean to coastal upwelling induced along the Venezuelan coast by a strengthening of the easterly trade winds. Variability in the atmospheric energy transport is associated with a cross-equatorial meridional overturning circulation that is only weakly associated with variability in the trade winds along the Venezuelan coast. In consequence, there is only very limited correlation between the atmosphere and Atlantic Ocean energy transports in the Tropics of HadCM3

Solid-state interconversions of coordination networks and hydrogen-bonded salts

Thermal or chemical treatment of crystalline 4,4-bipyridinium salts of [MCl4]2- (M=Co, Zn, Fe, or Pt) leads to HCl loss and formation of coordination network solids [{MCl2(4,4-bipy)}n]. For M=Co, Zn, and Fe, these solids can also be prepared by mechanochemical means. Their exposure to HCl vapor or the mechanochemical reaction of metal dichlorides with [4,4-H2bipy]Cl2 gives [4,4-H2bipy]2+ salts of [CoCl4]2-, [ZnCl4]2-, and, for the first time, [FeCl4]2-.

Crystal structure of (isothiocyanato)(2-pyridinecarboxaldehydebenzoylhydrazonato)copper(I),Cu(C13H10N3O)(NCS)

C14H10CuN4OS, monoclinic, P12(1)/nl (no. 14), a = 8.837(1) angstrom, b = 15.625(2) angstrom, c = 10.366(1) angstrom, beta = 103.36(1)degrees, V = 1392.6 angstrom(3), Z = 4, R-gt(F) = 0.029, WRref(F-2) = 0.076, T = 150 K.

Alkene-arene meta photocycloadditions with a four-carbon-atom tether: efficient approach toward the polycyclic ring systems of aphidicolin and stemodinone

At the end of its tether! The fusion of a six-membered ring onto the four-carbon-atom tether of substrate 1 provides an efficient approach toward the polycyclic ring systems of the natural products aphidicolin and stemodinone. The reaction represents a unique example of a preference for product formation from an endo exciplex in an intramolecular system (exo:endo 2:3=1.0:1.2).

Ligand bridging of the DNA Holliday junction: molecular recognition of a stacked-X four-way junction by a small molecule

Planning a Holliday: A new mode of binding to a stacked-X, four-way Holliday junction is described in which a chromophore molecule binds across the center of the junction and two adenine residues are replaced by the acridine chromophores at either side of the crossover. This binding mode is specific for the Holliday junction and does not cause unwinding of the DNA helices.