A silicon implementation of the fly's optomotor control system

Flies are capable of stabilizing their body during free flight by using visual motion information to estimate self-rotation. We have built a hardware model of this optomotor control system in a standard CMOS VLSI process. The result is a small, low-power chip that receives input directly from the real world through on-board photoreceptors and generates motor commands in real time. The chip was tested under closed-loop conditions typically used for insect studies. The silicon system exhibited stable control sufficiently analogous to the biological system to allow for quantitative comparisons

The influence of turbulence on the structure and propagation of enclosed flames

Although it has long been established that burning rates can be appreciably increased by turbulence, the actual extent of this increase and the precise mechanism involved are still far from clear. The object of the present research was to examine the effects of turbulence on burning velocity and on the physical structure of the flame surface under flow conditions similar to those experienced in turbojet afterburner systems

Spatial variability in the hyporheic zone refugium of temporary streams

A key ecological role hypothesized for the hyporheic zone is as a refugium that promotes survival of benthic invertebrates during adverse conditions in the surface stream. Many studies have investigated use of the hyporheic refugium during hydrological extremes (spates and streambed drying), and recent research has linked an increase in the abundance of benthic invertebrates within hyporheic sediments to increasing biotic interactions during flow recession in a temporary stream. This study examined spatial variability in the refugial capacity of the hyporheic zone in two groundwater-dominated streams which flow permanence varied over small areas. Two non- insect taxa, Gammarus pulex and Polycelis spp. Were common to both streams and were investigated in detail. Hydrological conditions in both streams comprised a four- month period of flow recession and low flows, accompanied by reductions in water depth and wetted width. Consequent declines in submerged benthic habitat availability were associated with increases in population densities of mobile benthic taxa, in particular G. pulex

Housing professionalism in the United Kingdom: the final curtain or a new age?

The unusually large, predominantly municipal, housing sector in the UK has provided the context for a large occupational grouping of "housing managers" that has claimed professional status. However, within the post-1945 British welfare state this professional project enjoyed limited success and social housing remained a fragile professional domain. This article explores the consequences for housing professionalism of the recent displacement of the bureau-professional "organisational settlement" by that characterising an emerging "managerial state". Managerialism constitutes a clear challenge to established forms of "professionalism", especially a weak profession such as housing management. However, professionalism is temporally and culturally plastic. Hence, the demands of managerialism, within the specific context of New Labour's quest for "community" cohesion, may be providing opportunities for a new urban network professionalism founded on claims to both generic and specific skills and also a knowledge base combining abstraction with local concreteness. The prominence in these networks of erstwhile "housing" practitioners may become the basis for a new, quite different, professional project. This argument is developed through both conceptual exploration and reference to empirical research. The latter involves reference to recent work by the authors on, first, the perception of housing employers of the changing nature and demands of "housing" work and its consequences for professionalism and, secondly, the professional project implications of the increasing prominence of neighbourhood management.</p

NHEP Support for DES Shellfish Program 2005

For the past three years, Great Bay Coast Watch (GBCW) volunteers have provided the New Hampshire Department of Environmental Services (NHDES) Shellfish Program with significant assistance in performing tasks necessary in managing shellfish resources for human safety. This report describes a continuation of this mutually beneficial partnership