Unusual spectral categories

Spectral Enrichments of Model Categories

We prove that every stable, combinatorial model category can be enriched in a natural way over symmetric spectra. As a consequence of the general theory, every object in such a model category has an associated homotopy endomorphism ring spectrum. Basic properties of these invariants are established.

On the Homotopy Theory of Spectral Categories

Let Sp be the category of symmetric spectra, regarded as having the stable model structure. We prove that the category of small categories enriched over Sp admits a model category structure. The method of proof applies to other categories than symmetric spectra as well, as long as these categories are linked to the category of simplicial sets via a certain strong monoidal Quillen pair.

Spectral Categories in the Learning Behaviour of Blowflies*

Wavelength discrimination in the flower visiting blowfly Lucilia spec, was investigated in an attempt to elucidate the mechanisms underlying colour vision in this insect. The flies were sub­ jected to a classical conditioning procedure in which they had to discriminate between a re­ warded and an unrewarded monochromatic light stimulus. The results reveal large wavelength ranges within which no...

3C 223.1: A source with unusual spectral properties

Analysis of Giant Metrewave Radio Telescope low frequency data for an X-shaped source, 3C 223.1 has revealed an unusual result. The radio morphologies of it at 240 and 610 MHz show well definedX-shape with a pair of active jets along the north-south axis and a pair of wings along the east-west axis, that pass symmetrically through the undetected radio core. The wings (or low surface brightness ...

Unusual spectral properties of a class of Schrödinger operators