The Ramsey Number for 3-Uniform Tight Hypergraph Cycles

Let C(3)n denote the 3-uniform tight cycle, that is, the hypergraph with vertices v1, .–.–., vn and edges v1v2v3, v2v3v4, .–.–., vn−1vnv1, vnv1v2. We prove that the smallest integer N = N(n) for which every red–blue colouring of the edges of the complete 3-uniform hypergraph with N vertices contains a monochromatic copy of C(3)n is asymptotically equal to 4n/3 if n is divisible by 3, and 2n otherwise. The proof uses the regularity lemma for hypergraphs of Frankl and Rödl

What punishment expresses

In this article, I consider the question of what punishment expresses and propose a way of approaching the question that overcomes problems in both psychosocial and philosophical expressivist traditions. The problem in both traditions is, I suggest, the need for an adequate moral – neither moralizing nor reductive – psychology, and I argue that Melanie Klein’s work offers such a moral psychology. I offer a reconstruction of Klein’s central claims and begin to sketch some of its potential implications for an expressive account of punishment. I outline a Kleinian interpretation of modern punishment’s expression as of an essentially persecutory nature but also include depressive realizations that have generally proved too difficult for liberal modernity to work through successfully, and the recent ‘persecutory turn’ is a defence against such realizations. I conclude by considering the wider philosophical significance of a Kleinian account for the expressivist theory of punishment

Host recognition in a desert mistletoe: Early stages of development are influenced by substrate and host origin

1. In many root parasites, chemical substances from the host are necessary for the successful initiation of germination and holdfast formation, and are the basis for host recognition and localization within the rhizosphere. In contrast, bird-dispersed mistletoe seeds have no need for the chemical localization of a host, and possible mechanisms of host recognition are poorly understood. Many studies claim that mistletoes germinate readily in the absence of a host and independent of the substrate. 2. In this study, the possible occurrence of substrate dependence and host recognition in mistletoes during the establishment of Plicosepalus acaciae Zucc. seeds on Acacia raddiana Savi was tested experimentally. 3. In a laboratory experiment, no influence of substrate on germination could be found, but a significantly higher proportion of the germinated seeds developed a holdfast on natural (bark) substrate than on artificial (plastic) substrate. Moreover, the origin of the bark had a significant influence on holdfast formation frequency. 4. Host influence was additionally tested in a reciprocal transplant experiment in two field sites with genetically different populations of the same host species. Those mistletoes of local origin germinated significantly more often than their non-local counterparts. 5. These results suggest the existence of interactions between mistletoe seed and host branch on the basis of chemical cues that are active at an early stage of seedling development and are host-specific at the level of populations.Articl