A Svarc-Milnor lemma for monoids acting by isometric embeddings

We continue our programme of extending key techniques from geometric group theory to semigroup theory, by studying monoids acting by isometric embeddings on spaces equipped with asymmetric, partially-defined distance functions. The canonical example of such an action is a cancellative monoid acting by translation on its Cayley graph. Our main result is an extension of the Svarc-Milnor Lemma to this setting.Comment: 11 page

The Determination of the Homogeneity of a Vitis vinif era L. cv. Cape Riesling Vineyard

The value of Principal Component and Stepwise Discriminant analyses in selecting uniform plants for experimental purposes is discussed. Twenty seven variables were taken into account to establish the homogeniety (uniform plants) of 297 Vitis vinifera L. cv. Cape Riesling vines. A detailed study of the relationship and interrelationship of these variables resulted in 208 vines being selected as a uniform population. This selection provides the researcher with the possibility of using single vines as experimental units. However, it must be pointed out that Principal Component and Stepwise Discriminant analyses can only be used as an aid to normal statistical evaluation of experimental results and not as substitute for statistical experimental design

Quasi-morphisms and L^p-metrics on groups of volume-preserving diffeomorphisms

Let M be a smooth compact connected oriented manifold of dimension at least two endowed with a volume form. We show that every homogeneous quasi-morphism on the identity component $Diff_0(M,vol)$ of the group of volume preserving diffeomorphisms of M, which is induced by a quasi-morphism on the fundamental group, is Lipschitz with respect to the L^p-metric on the group $Diff_0(M,vol)$. As a consequence, assuming certain conditions on the fundamental group, we construct bi-Lipschitz embeddings of finite dimensional vector spaces into $Diff_0(M,vol)$.Comment: This is a published versio

A Comparative Anatomical Study of the Grapevine, Shoot and Cane: II: Periderm and Secondary Phloem

The taxonomic value of ten periderm and secondary phloem features of canes of different grapevine species was investigated. A scatter diagram showed that with few exceptions the American cultivars have a larger periderm with smaller secondary phloem, while the reverse was true for European cultivars. Crosses tend to cluster with one of their parents. It has been found that the largest intercultivar variation occurs at either the middle of the shoot length or the ventral sides of the basal part of the shoots

A Comparative Anatomical Study of the Grapevine Shoot: I Epidermis

Material gathered from three positions on the shoot and cane during veraison and two weeks after harvest were investigated for taxonomic features concerning the epidermis. Stomata and lenticels were present in all the cultivars studied, but trichomes were frequently present only on 99 Richter. Based on epidermal characteristics a dendogram giving the percentage similarity between cultivars, was constructed, and from this was concluded that concerning taxonomic features on Vitis vinifera L. cultivars tend to have a more than 90% similarity irrespective of the position on the shoot

Diamphotoxin: the arrow poison of the Kung bushmen

Purification de la diamphotoxine et étude de ses caractéristiques pharmacologiques et biochimiques

Strongly bounded groups and infinite powers of finite groups

We define a group as strongly bounded if every isometric action on a metric space has bounded orbits. This latter property is equivalent to the so-called uncountable strong cofinality, recently introduced by G. Bergman. Our main result is that G^I is strongly bounded when G is a finite, perfect group and I is any set. This strengthens a result of Koppelberg and Tits. We also prove that omega_1-existentially closed groups are strongly bounded.Comment: 10 pages, no figure. Versions 1-3 were entitled "Uncountable groups with Property (FH)". To appear in Comm. Algebr

Profinite completion of Grigorchuk's group is not finitely presented

In this paper we prove that the profinite completion $\mathcal{\hat G}$ of the Grigorchuk group $\mathcal{G}$ is not finitely presented as a profinite group. We obtain this result by showing that H^2(\mathcal{\hat G},\field{F}_2) is infinite dimensional. Also several results are proven about the finite quotients $\mathcal{G}/ St_{\mathcal{G}}(n)$ including minimal presentations and Schur Multipliers

Growth characteristics of vitis vinifera L. cv. Cape Riesling

CITATION: De La Harpea, A. C. & Visser, J. H. 1985. Growth characteristics of vitis vinifera L. cv. Cape riesling. South African Journal of Enology & Viticulture, 6(1):1-6, doi:10.21548/6-1-2352.The original publication is available at http://www.journals.ac.za/index.php/sajevThe effect of topping on the growth behaviour of Vitis vinifera L. cv. Cape Riesling vineyard was investigated. Shoot and leaf growth of both topped and untopped vines, can be described as sigmoidal. Shoot (cm) and leaf growth (cm') of the topped vines were significantly more than that of the untopped vines and are attributed to lateral shoot growth. Topping had no effect on bunch development. The development of skin, pulp and seed of both topped and untopped vines expressed as a percentage dry mass per berry can be described by a hyperbolic function for the skin, linear for the pulp and parabolic for the seed.http://www.journals.ac.za/index.php/sajev/article/view/2352Publisher's versio