Security Implications of Typical Grid Computing Usage Scenarios

Grid Computing consists of a collection of heterogeneous computers and resources spread across multiple administrative domains with the intent of providing users uniform access to these resources. There are many ways to access the resources of a Grid, each with unique security requirements and implications for both the resource user and the resource provider. A comprehensive set of Grid usage scenarios is presented and analyzed with regard to security requirements such as authentication, authorization, integrity, and confidentiality. The main value of these scenarios and the associated security discussions is to provide a library of situations against which an application designer can match, thereby facilitating security-aware application use and development from the initial stages of the application design and invocation. A broader goal of these scenarios is to increase the awareness of security issues in Grid Computing.     

Activity-dependent plastic changes in the motor nerve terminals of the adult rat

Summary— Small and short-lasting physiologic variations in the locomotor activity of normal adult rats can induce remodelling in the motor nerve endings of the fast extensor digitorum longus muscle. The specificity and relative importance of the different plastic adaptations occurring in the presynaptic axonal tree have been studied, in silver impregnated nerve endings, by using an automatic image analysis treatment of the nerve terminals' geometric properties and a discriminant analysis of the morphometric parameters. Changes observed, like selective length variations in certain terminal segments and positional rearrangements, agree with a mechanism of neural connectivity regulation in the adult that arises as a consequence of normal neuromuscular activity.     

Phenomenological theory of GC/AT pressure on DNA base composition

Summary We present a phenomenological theory expressing the constraints operating on the (G+C) contents of the three codon positions, i.e., first, second, and third bases of codons, by using the smallest number of constraint parameters having clear physical and genetic meaning. Theoretical curves displaying base composition at each of the three codon sites are given. The agreement between the theoretical curves and the data points of 1277 genes is quite good irrespective of the species from which the DNAs originated; the curves might be universal ones and the constraint parameters might have general biological meanings in relation to the DNA/RNA and protein functions.