Developmental basis of limb homology in Pleurodiran turtles, and the identity of the hooked element in the chelonian tarsus

Although Pleurodiran turtles represent an important component of extant turtle radiation, our knowledge of the development and homology of limb bones in turtles rests mostly upon observations made on derived members of the Cryptodiran clade. Herein, we describe limb development in three pleurodirans: Podocnemis unifilis Troschel, 1848, Podocnemis sextuberculata Cornalia, 1849 and Phrynops hilarii (Dumeril and Bibron, 1835), in an effort to contribute to filling this anatomical gap. For earlier stages of limb development, we described the Y-shaped condensation that gave rise to the zeugopodial cartilages, and differentiation of the primary axis/digital arch that reveals the invariant pattern common to tetrapods. There are up to four central cartilaginous foci in the carpus, and the proximal tarsale is formed by the fusion of the fibulare, intermedium, and centrale 4. Digital development is similar for the five digits. Changes in toe V occur predominantly in the distal tarsale 5. Ontogenetic reduction of phalanges is observed in toe V of Podocnemis. Based on these results, we suggest that the hooked element present in the chelonian tarsus, and traditionally recognized as a modified fifth metatarsale, is actually the fifth distal tarsale. Additionally, our data on limb development of pleurodiran turtles supply more taxonomically comprehensive information to interpret limb configuration within the chelonian clade. (C) 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155, 845-866.

Electrocardiographic manifestation of the middle fibers/septal fascicle block: a consensus report

There are fibers in the left ventricle (LV) (LV middle network) that in around one third of cases may be considered a true septal fascicle that arises from the common left bundle. Its presence and the evidence that there are 3 points of activation onset in the LV favor the quadrifascicular theory of the intravantricular activation of both ventricles. Since the 70s, different authors have suggested that the block of the left middle fibers (MS)/left septal fascicle may explain different electrocardiographic (ECG) patterns. The 2 hypothetically based criteria that are in some sense contradictory include: a) the lack of septal "q" wave due to first left and later posteriorly shifting of the horizontal plane loop and b) the presence of RS in lead V-2 (V-1-V-2) due to some anterior shifting of the horizontal plane vectorcardiogram loop. However, there are many evidence that the lack of septal q waves can be also explained by predivisional first-degree left bundle-branch block and that the RS pattern in the right precordial leads may be also explained by first-degree right bundle-branch block. The transient nature of these patterns favor the concept that some type of intraventricular conduction disturbance exists but a doubt remains about its location. Furthermore, the RS pattern could be explained by many different normal variants. To improve our understanding whether these patterns are due to MF/left septal fascicle block or other ventricular conduction disturbances (or both), it would be advisable: 1) To perform more histologic studies (heart transplant and necropsy) of the ventricular conduction system; 2) To repeat prior experimental studies using new methodology/technology to isolate the MF; and 3) To change the paradigm: do not try to demonstrate if the block of the fibers produces an ECG change but to study with new electroanatomical imaging techniques, if these ECG criteria previously described correlate or not with a delay of activation in the zone of the LV that receives the activation through these fibers or in other zones. (C) 2012 Elsevier Inc. All rights reserved.

A new aspect of sign and its implications for the Theory of Communication

Este artigo propõe que a semiótica peirceana pode oferecer bases tanto lógicas quanto epistemológicas para a busca de uma teoria geral da comunicação. No entanto, o desenvolvimento de uma teoria semiótica da comunicação depende, em primeiro lugar, de uma melhor compreensão dos aspectos formais do signo, tarefa atribuída por Peirce à gramática, o primeiro ramo de sua semiótica. Nós apresentamos uma análise das relações do signo, revelando um aspecto não trabalhado por Peirce, ampliando seu número para onze. Este novo aspecto é a relação triádica entre signo, objeto dinâmico e interpretante dinâmico (S-OD-ID). Nós defendemos que esta relação é essencial para a compreensão da comunicação como semiose, por dar conta da repetição ou redundância do signo comunicativo, quando se cria ou transmite informação. O artigo pretende dar um passo a mais na direção de uma teoria da comunicação verdadeiramente universal, através do vínculo entre a semiótica peirceana e a moderna filosofia da linguagem.