Data on the distribution of collagen fibril diameters in various connective tissues have been collected and analysed for common features. The diameter distributions of the collagen fibrils at birth and in the foetal stages of development are unimodal, whereas at maturity the mass-average diameter of the collagen fibrils is generally larger than at birth and the distributions of fibril sizes may be either unimodal or bimodal depending on the tissue. At senescence, few data are available but in most instances both the mean and mass-average diameters of the collagen fibrils are smaller than those at maturity and the fibril distributions are mainly bimodal. The division between tissues showing unimodal or bimodal fibril distributions at maturity does not simply relate to the type I collagen/type II collagen classification, to the distinction between orientated and unorientated material or indeed directly to the levels of stress and strain encountered by the tissue. However, there may prove to be a relation between a bimodal fibril diameter distribution at maturity and the maintenance over long periods of time of either high stress in stretched tissues or low stress in compressed tissues. It has also been noted that the width of the collagen fibril diameter distribution at birth differs between altricious and precocious animals. The ultimate tensile strength of a connective tissue and the mass-average diameter of the constituent collagen fibrils have been shown to have a positive correlation. Further, the form of the collagen fibril diameter distribution can be directly related to the mechanical properties of the tissue. In particular, it is postulated that the size distribution of the collagen fibrils is largely determined by two factors. First, if the tissue is primarily designed to have high tensile strength, then an increase in the diameter of the collagen fibrils will parallel an increase in the potential density of intrafibrillar covalent crosslinks. Consequently large collagen fibrils are predicted to have a greater tensile strength than small fibrils. Secondly, if the tissue is designed to be elastic and hence withstand creep, then a reduction in the diameter of the collagen fibrils will effectively increase the surface area per unit mass of the fibrils thus enhancing the probability of interfibrillar non-covalent crosslinks between the collagen fibrils and the components of the matrix. The idealized description given may indicate how the mechanical properties of a tissue may be interpreted in terms of the collagen fibril diameter distribution.

No abstract

Corn based extrudates produced at three moisture contents and stored at four water activities were evaluated by sensory evaluation and instrumental tests in order to assess how processing and storage affect the sensory characteristics of the products. Acoustic signatures were collected by recording the sounds produced as the samples were bitten through with the back molars. These signatures were analyzed by fast Fourier transformation and the Kolmogorov dimension of fractal analysis. Products with a low moisture content and water activity were crisper than those at a higher moisture content and water activity. Fourier transformations of the data showed peaks between 1 and 2 kHz and between 6 and 7 kHz. Fractal analysis of the normalized raw time‐amplitude curves showed significant positive correlations between fractal dimensions and the sensory characteristics of crispness, crumbliness and pitch.

No abstract

SUMMARY A horse with rostral displacement of the palatopharyngeal arch was found to have a bilaterally symmetrical deformity of the laryngeal area. Both left and right cricopharyngeal muscles were absent. The shape of the thyroid cartilage was grossly abnormal and vestiges of the cricothyroid muscles were attached only to the cricoid cartilage. It was suggested that such an anomaly could have resulted from aberrant development of the fourth branchial arch. RÉSUMÉ Un cheval présentait un déplacement rostral de l'arc palato‐pharyngien. Il présentait également une déformation bilatérale et symétrique de la région laryngée. Les muscles crico‐pharyngiens droit et gauche étaient absents. La forme du cartilage thyroïde était anormale et des vestiges des muscles crico‐thyroïdiens étaient insérés sur le cartilage cricoïde. Une telle anomalie peut résulter d'un développement perturbé du 4ème arc branchial. ZUSAMMENFASSUNG Ein Pferd mit einer Verlagerung des Gaumen‐Rachen‐bogen nach rostral wies eine bilateral symmetrische Deformation der Larynxgegend auf. Die beiderseitigen Cricopharyngealmuskeln fehlten. Die Gestalt des Thy‐roidknorpels war stark verändert und Ueberreste von Cricothyroidmuskulatur fanden sich nur am Cricoid‐knorpel befestigt. Es wird vermutet, dass sich eine derartige Anomalie aus einer Fehlentwicklung des vierten Kiemenbogens ergeben haben könnte.