We study group extensions A -• Γ -> Ω, where Γ acts on a C*-algebra si. Given a twisted covariant representation π, V of the pair si, A we construct 3-cocycles on Ω with values in the centre of the group generated by V(A). These 3-cocycles are obstructions to the existence of an extension of Ω by V(A) which acts on si compatibly with Γ. The main theorems of the paper introduce a subsidiary inva...

the aim of the present paper is to sbo» that anti-realism in science, 1vhich has a1;guab/y become more fashionable in recentyears, contrary to tuha: its proponents assert, cannot make use of quantum mechanics and its impressiue achievements as a frump card in justifying its claims. i will argue that scientific anti-realism far from providing scientific communiry with a progressive methodologica...

After the dual resonance model was formulated in terms of infinitely many oscillators by Nambu, Veneziano and Fubini,l) it has been frequently suggested that the underlying string model of hadrons furnishes the multiparticle dual am,. plitudes.) One of the most crucial problems in the dual resonance model, however, is the existence of ghosts which are unphysical states having negative norms or ...

This paper describes a technique, called Object-Oriented Fragmented Data Processing, for jointly improving the reliability and security with which distributed computing systems process sensitive information. The technique protects the information contained in, and the processing performed by, a given object by first fragmenting the object into the subsidiary objects of which it is composed. It ...

We introduce the generalized devil's lenses (GDLs) as a new family of diffractive kinoform lenses whose structure is based on the generalized Cantor set. The focusing properties of different members of this family are analyzed. It is shown that under plane wave illumination the GDLs give a single main focus surrounded by many subsidiary foci. It is shown that the total number of subsidiary foci...

Subsidiary development is a multi-dimensional construct that cannot be captured just by looking at subsidiary roles, activities, etc. Three distinct dimensions of subsidiary development are identified and these are: scope of subsidiary (the breadth of activities), level of subsidiary competence (the depth of activities) and level of integration in the internal MNC-network. Birkinshaw and Hood (...

the electronic conductance at zero temperature through a quantum wire with side-connected asymmetric quantum ring (as a scatter system) is theoretically studied using the non-interacting hamiltonian anderson tunneling method. in this paper we concentrate on the configuration of the quantum dot rings. we show that the asymmetric structure of qd-scatter system strongly influences the amplitude an...