An unprecedented macrocyclic dimeric diterpene containing a C2 symmetry axis was isolated from Acacia schaffneri . This compound, named schaffnerine, was characterized as (5S,7S,8R,9R,10S,17S,5'S,7'S,8'R,9'R,10'S,17'S)-7,8:7,17':16,17:17,7':7',8':16',17'-hexaepoxy-7,8-seco-7',8'-seco-dicassa-13,13'-diene (1) from its spectroscopic data. Comparison of its experimental vibrational circular dichro...

John M. Gauchl, Stephen M. Pizer1,2 Departments of Computer Science I and Radiology2 University of North Carolina, Chapel Hill, North Carolina, USA A fundamental approach for providing an image description in terms of visually sensible image regions is described. It involves a) the representation of the image by a structure that captures essential image information and then b) the definition of...

The Concordance-based Medial Axis Transform (CMAT) presented in this paper is a multiscale medial axis (MMA) algorithm that computes medial evidence from grey-level boundary measures. It differs from previous algorithms of this type in considering the symmetry of both boundary position and strength. The resultant MMA transform is not prone to the generation of spurious medial responses exhibite...

In the title compound, C(11)H(6)N(2)O, the complete mol-ecule is generated by the application of crystallographic twofold symmetry (the mol-ecule is disordered about this axis). The prop-2-yn-1-yl residue is slightly twisted out of the plane of the benzene ring [C-O-C-C torsion angle = 173.1 (3)°] and is orientated away from the nitrile substituents. In the crystal, supra-molecular chains along...

Symmetrical human faces are attractive. Two explanations have been proposed to account for symmetry preferences: (i) the evolutionary advantage view, which posits that symmetry advertises mate quality and (ii) the perceptual bias view, which posits that symmetry preferences are a consequence of greater ease of processing symmetrical images in the visual system. Here, we show that symmetry prefe...

Elucidating the structure of Aβ(1-40) fibrils is of interest in Alzheimer's disease research because it is required for designing therapeutics that target Aβ(1-40) fibril formation at an early stage of the disease. M35 is a crucial residue because of its potential oxidation and its strong interactions across β-strands and across β-sheets in Aβ fibrils. Experimentally, data for the three-fold sy...

A novel analytical approach is proposed for the characterization of organic molecular crystal structures where close packing is an important factor. It requires the identification of a unique reference axis within the crystal, along which three-dimensional space is divided into close-packed blocks (CPB) and junction zones (JZ). The degree of close packing along the reference axis is quantified ...

Abstract.We propose a normalized parameter for characterization of similarity/dissimilarity of two sequences providing a smoothly varying measure for varying symmetry score. Such a parameter can be used for analysis of experimental data and fitting to a theoretical model, mirror symmetry estimation with respect to a selected or presumed symmetry axis, in particular, in symmetry detection applic...

Decorin and its associated glycosaminoglycan (GAG) side chain, dermatan sulfate (DS), play diverse roles in soft tissue formation and potentially aid in the mechanical integrity of the tissue. Deeper understanding of the distribution and orientation of the GAGs on a microscopic level may help elucidate the structure/function relationship of these important molecules. The hypothesis of the prese...

Bilateral or mirror symmetry is a ubiquitous feature of biological forms that the visual system could exploit for segmenting an object from a cluttered background. If this is so, the visual system may be prepared to detect symmetry at all retinal locations in parallel. Indeed, a biologically plausible model that responds optimally at axes of symmetry is quite easy to construct. Our data show, h...