Publications

Interdisciplinary research in human vision and electronic imaging has greatly contributed to the current state of the art in imaging technologies. Image compression and image quality are prominent examples and the progress made in these areas relies on a better understanding of what natural images are and how they are perceived by the human visual system. A key research question has been: given the (statistical) properties of natural images, what are the most efficient and perceptually relevant image representations, what are the most prominent and descriptive features of images and videos?We give an overview of how these topics have evolved over the 25 years of HVEI conferences and how they have influenced the current state of the art. There are a number of striking parallels between human vision and electronic imaging. The retina does lateral inhibition, one of the early coders was using a Laplacian pyramid; primary visual cortical areas have orientation- and frequency-selective neurons, the current JPEG standard defines similar wavelet transforms; the brain uses a sparse code, engineers are currently excited about sparse coding and compressed sensing. Some of this has indeed happened at the HVEI conferences and we would like to distill that.

n/a

This paper shows that the Aeolic inf. νηφέμεν used in Archil. 4.9 W instead of expectable νήφειν in the beginning of a pentameter is problematic: it cannot be a metrical variant, since Ionic νήφειν would be unimpeachable in the first part of a pentameter colon (where a contracted biceps is entirely admissible), and it cannot simply be put down as an epicism, since νήφω, a very colloquial verb, is never used in the heroic epic that came down to us and is very unlikely to have ever been used in this genre. The rare instances of Aeolic infinitives in -έμεν in the language of elegy can be shown to be dependent on epic models of one kind or another (e.g. γηρᾱσέμεν Simon. 20.7 W.2). Assuming that the form νηφέμεν is Archilochus’ own coinage, therefore, the question is whether the poet intended the final distich of fr. 4 to resonate with the epic tradition; and if so, whether it was a specific allusion to a fixed text or a reference to a broader tradition. It is argued that νηφέμεν should be viewed as modeled on πινέμεν from the famous midsummer picnic scene in Hesiod (Op. 592, construed with αἴθοπα οἶνον): the combination of the high-flown ending, best known from the epic dialect, with a lowly root νηφ- must have both produced a comic effect in the context of an invitation to get drunk on duty and serve as an allusion to the well-known passage in Hesiod.

The immunologically important major histocompatibility complex (MHC) harbors some of the most polymorphic genes in vertebrates. These genes presumably evolve under parasite-mediated selection and frequently show inconsistent allelic genealogies, where some alleles are more similar between species than within species. This phenomenon is thought to arise either from convergent evolution under parallel selection or from the preservation of ancient allelic lineages beyond speciation events (trans-species polymorphism, TSP). Here we examine natural populations of two sympatric stickleback species (Gasterosteus aculeatus and Pungitius pungitius) to investigate the contribution of these two mechanisms to the evolution of inconsistent allelic genealogies at the MHC. Overlapping parasite taxa between the two host species in three different habitats suggest contemporary parallel selection on the MHC genes. Accordingly, we detected a lack of species-specific phylogenetic clustering in the immunologically relevant antigen-binding residues of the MHC IIB genes which contrasted with the rest of the coding and non-coding sequence. However, clustering was not habitat-specific and a codon-usage analysis revealed patterns of similarity by descent. In this light, common descent via TSP, in combination with intra-species gene conversion, rather than convergent evolution is the more strongly supported scenario for the inconsistent genealogy at the MHC.