Growth rates of bacteria in rivers

Three different methods for determining bacterial growth rate in rivers are described. Two of the methods are for bacteria in suspension: a recirculating experimental channel method and a radioactive tracer technique using super(35)SO sub(4). The third method is for bacteria attached to surfaces and specifically considers the surface of the common duckweed Lemna minor)

Silvopastoral agroforestry - an option to support sustainable grassland intensification

N/

The work of making Malta : the Council of Europe's Archaeology and Planning Committee 1988-1996

This article began life as a paper in the session ‘Opening Doors for Archaeologists: Making Malta Work’ at the 2006 EAA Annual Meeting in Kracow, Poland. It explores the background of the European Convention on the Protection of the Archaeological Heritage (Revised), also known as the Valletta Convention or the Convention of Malta. The article examines some of the major issues that were discussed and describes the drafting process of the Convention from the author’s personal perspective as one of the members of the committee responsible. It concludes with a brief consideration of some subsequent developments and a plea for a more active role for the EAA at Strasbourg and Brussels. Keywords: archaeological heritage management, Convention of Malta, Council of Europe, heritage protection, Valletta Conventionpeer-reviewe

The Stiles-Crawford Effect in the Eye of the Blowfly, Calliphora erythrocephala

Stiles-Crawford-like effects (that is, directional sensitivity of the retina) were investigated in the fly’s eye. Intracellular recordings from the visual sense cells were made, and the radiation patterns emerging from the photoreceptors with antidromic light were photographed, and evaluated with a microdensitometer. The measurements from both methods agree well, and can be satisfactorily described by a theoretical model based on waveguide theory. Clear radiation patterns from the first and second order modes were observed at the level of the cornea. As in the vertebrate eye, the photoreceptors are aligned towards the center of the lens, a phenomenon for which a theoretical explanation is proposed.

Directional Tuning Curves, Elementary Movement Detectors, and the Estimation of the Direction of Visual Movement

Both the insect brain and the vertebrate retina detect visual movement with neurons having broad, cosine-shaped directional tuning curves oriented in either of two perpendicular directions. This article shows that this arrangement can lead to isotropic estimates of the direction of movement: for any direction the estimate is unbiased (no systematic errors) and equally accurate (constant random errors). A simple and robust computational scheme is presented that accounts for the directional tuning curves as measured in movement sensitive neurons in the blowfly. The scheme includes movement detectors of various spans, and predicts several phenomena of movement perception in man.

AuNx stabilization with interstitial nitrogen atoms: A Density Functional Theory Study

Researchers have been studying 4d and 5d Series Transition Metal Nitrides lately as a result of the experimental production of AuN, PtN, CuN. In this paper, we used the Density Functional Theory (DFT) implementing a pseudopotential plane-wave method to study the incorporation of nitrogen atoms in the face-centered cube (fcc) lattice of gold (Au). First, we took the fcc structure of gold, and gradually located the nitrogen atoms in tetrahedral (TH) and octahedral (OH) interstitial sites. AuN stabilized in: 2OH (30%), 4OH and 4TH (50%), 4OH - 2TH (close to the wurtzite structure) and 6TH (60%). This leads us to think that AuN behaves like a Transition Metal Nitride since the nitrogen atoms look for tetrahedral sites. © Published under licence by IOP Publishing Ltd

QCD Corrections to Electroweak Annihilation Decays of Superheavy Quarkonia

QCD corrections to all the allowed decays of superheavy groundstate quarkonia into electroweak gauge and Higgs bosons are presented. For quick estimates, approximations that reproduce the exact results within less than at worst two percent are also given.Comment: 20 pages RevTeX, 9 figures. The complete paper, including figures, is also available via anonymous ftp at (129.13.102.139) as ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-05/ttp95-05.ps, or via www at http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints

The role of body wall muscles in C. elegans locomotion

Over the past four decades, one of the simplest nervous systems across the animal kingdom, that of the nematode worm C. elegans, has drawn increasing attention. This system is the subject of an intensive concerted effort to understand the behaviour of an entire living animal, from the bottom up and the top down. C. elegans locomotion, in particular, has been the subject of a number of models, but there is as yet no general agreement about the key (rhythm generating) elements. In this paper we investigate the role of one component of the locomotion subsystem, namely the body wall muscles, with a focus on the role of inter-muscular gap junctions. We construct a detailed electrophysiological model which suggests that these muscles function, to a first approximation, as mere actuators and have no obvious rhythm generating role. Furthermore, we show that within our model inter-muscular coupling is too weak to have a significant electrical effect. These results rule out muscles as key generators of locomotion, pointing instead to neural activity patterns. More specifically, the results imply that the reduced locomotion velocity observed in unc-9 mutants is likely to be due to reduced neuronal rather than inter-muscular coupling

Emeritus Professor J.N. Hutchinson : Historical Landslide Collection : Great Britain

This report describes a collection of material, field documents, aerial photographs, reports, maps and reference material, which was bequeathed to the British Geological Survey by Professor J. N. Hutchinson. Any material pertaining to Great Britain was sorted into geographical regions and catalogued with the remaining material archived within the National GeoSceince Data Centre to be catalogued at a later date