Geometric Links Between 2d Patterns and 3d Structures in Islamic Architectures of Andalusia - Abstract

The paper intends to highlight the links between two-dimensional geometric matrices and three-dimensional structures in Andalusian architectures of Islamic origin. The deep ambivalence between plane and spatial geometries maintains a very strong evidence, for example, in the flat projections of the articulated vaulted surfaces ribs or the muquarnas cellular structures. The creative process underlying the geometric grid systems of these shapes is based on analogous proportioning systems and geometries, underlying the plane patterns. This article then analyzes in particular the geometrical principles, the transformations and the design aspects that were used to create the modules of the flat decorations and how they can be understood as structural schemes for the architectural buildings. To this end, some emblematic buildings of Islamic architectural production in Andalusia were examined, focusing on the most significant dome structures. In these it was possible to highlight how the purely ornamental aspect linked to the geometric design, constantly interacts with the architectural form

The effect of subminimal inhibitory concentrations of penicillin on growth rate and haemolysin activity of group G Streptococcus

The influence of the subminimal inhibitory concentrations (1/3 and 1/4 of the MIC) of penicillin on growth rate and on haemolysin production of a strain of group G Streptococcus was studied. It was shown that 1/3 of the MIC almost completely inhibited the bacterial growth, but it was not able to inhibit haemolysin activity in the culture supernate. The generation time of bacteria grown in 1/4 of the MIC was approximately twice longer than that of the control culture. In all cultures, the haemolysin, after being produced (or liberated), reached a peak and decreased to low levels, which could suggest that group G Streptococcus produces some end products of metabolism that are able to inhibit haemolysin activity

RESULTS OF HURWITZ TYPE FOR FIVE OR MORE SQUARES

Let rk(n) denote the number of representations of n as a sum of k squares. We give many cases (for k = 5, 6, 7) in which the generating function n≥0 rk(an + b)q n is a simple infinite product. For instance, r7(24n + 23)q n = 49728 � (1 − q2n) 10 (1 − q3n) 3 (1 − qn) 6 n≥0 n≥