LETS get real: constraints on the development of Local Exchange Trading Schemes

Local Exchange Trading Schemes (LETS) are widely promoted as a new tool for local economic development, but until recently the focus has been on their alleged ‘potential’ rather than the realities of their operation. This paper assesses the practical economic role of LETS by examining the amount of trading conducted, and demonstrates that both the volume of trading and the value of the trades are very low. Drawing on an intensive case study of the first UK LETS created explicitly as part of a local authority’s anti-poverty strategy, explanations for the low levels of participation are suggested, and significant structural constraints on the development of LETS are identified

Characterization of the Thermal Environment during Transport of Commercial Broiler Chickens

Transport of commercial broiler chickens from the farm to the processing plant is perceived to compromise welfare under some circumstances. Research has been conducted using European standard equipment to characterize the environment experienced by poultry during broiler transport. In contrast no studies have been reported on the environment experienced by broilers under United States standard industry practices during transport. Moreover, microenvironment temperatures within industry trailers have not been reported. The present study characterized the thermal micro-environment experienced by broiler chickens during transport across different seasons. The temperatures were influenced by temperature mitigation practices (plastic wrap, double side board, single side board, open side, and heat mitigation) and by ambient temperatures. Temperatures measured within transporters were found to have less variation compared to studies using other transport systems. Temperatures were found to decrease (p=0.05) for the second half of transport duration during low ambient conditions (-16.4 to 2.80 0C). For moderate ambient conditions (6.22 to 23.35 0C) significant (p=0.05) yet small (\u3c2oC) changes in temperature were seen. For transport within high ambient temperature ranges (29.05 to 40.14 0C) an increase (p\u3c0.05) in temperature was seen from the first to second half of transport duration. While temperature mitigation practices do provide improved thermal environments compared to that of ambient conditions, improvements are still needed. Further research is needed to develop new mitigation practices at high (29.05 to 40.14 0C) and low (-16.4 to 2.80 0C) ambient temperatures. Research is also needed to expand current indexes that consider the effects of temperature, humidity, air velocity, and duration to ensure welfare is not compromised by the transport environments experienced by poultry

Optimization of the Light Environment for Broiler Chickens

The use of artificial light sources has been necessitated by the use of fully enclosed rearing facilities for improved environmental control. Light Emitting Diodes (LED) have been developed as a light source that reduce the utilities required to provide equal light to that of incandescent sources. The following reports were carried out to investigate the effects of two light color temperatures, light intensity and light intensity gradients on broiler chicken production and behavior. The first investigation consisting of two consecutive trials investigated the effect of two light color temperatures (2700 K and 5000 K) in addition to the preference for each. It was found that broilers provided a choice between 2700 K and 5000 K had greater (p0.05) was found between BW or BW CV for each of the treatments. In the final report the use of feed line lighting was compared to conventional overhead lighting. The effect of the gradient (90 lx to 30 lx) resulted in similar production to that of a conventional uniform lighting environment of 20 lx. The use of preference and choice in light environments has been suggested to improve the production and wellbeing of broiler chickens in all three of the reports using light color temperature, light intensity, and light intensity gradients

Mixing with the radiofrequency single-electron transistor

By configuring a radio-frequency single-electron transistor as a mixer, we demonstrate a unique implementation of this device, that achieves good charge sensitivity with large bandwidth about a tunable center frequency. In our implementation we achieve a measurement bandwidth of 16 MHz, with a tunable center frequency from 0 to 1.2 GHz, demonstrated with the transistor operating at 300 mK. Ultimately this device is limited in center frequency by the RC time of the transistor's center island, which for our device is ~ 1.6 GHz, close to the measured value. The measurement bandwidth is determined by the quality factor of the readout tank circuit.Comment: Submitted to APL september 200

Development of an empirically based dynamic biomechanical strength model

The focus here is on the development of a dynamic strength model for humans. Our model is based on empirical data. The shoulder, elbow, and wrist joints are characterized in terms of maximum isolated torque, position, and velocity in all rotational planes. This information is reduced by a least squares regression technique into a table of single variable second degree polynomial equations determining the torque as a function of position and velocity. The isolated joint torque equations are then used to compute forces resulting from a composite motion, which in this case is a ratchet wrench push and pull operation. What is presented here is a comparison of the computed or predicted results of the model with the actual measured values for the composite motion

Couplerlib: a metadata-driven library for the integration of multiple models of higher and lower trophic level marine systems with inexact functional group matching

End-to-end modelling is a rapidly developing strategy for modelling in marine systems science and management. However, problems remain in the area of data matching and sub-model compatibility. A mechanism and novel interfacing system (Couplerlib) is presented whereby a physical–biogeochemical model (General Ocean Turbulence Model–European Regional Seas Ecosystem Model, GOTM–ERSEM) that predicts dynamics of the lower trophic level (LTL) organisms in marine ecosystems is coupled to a dynamic ecosystem model (Ecosim), which predicts food-web interactions among higher trophic level (HTL) organisms. Coupling is achieved by means of a bespoke interface, which handles the system incompatibilities between the models and a more generic Couplerlib library, which uses metadata descriptions in extensible mark-up language (XML) to marshal data between groups, paying attention to functional group mappings and compatibility of units between models. In addition, within Couplerlib, models can be coupled across networks by means of socket mechanisms. As a demonstration of this approach, a food-web model (Ecopath with Ecosim, EwE) and a physical–biogeochemical model (GOTM–ERSEM) representing the North Sea ecosystem were joined with Couplerlib. The output from GOTM–ERSEM varies between years, depending on oceanographic and meteorological conditions. Although inter-annual variability was clearly present, there was always the tendency for an annual cycle consisting of a peak of diatoms in spring, followed by (less nutritious) flagellates and dinoflagellates through the summer, resulting in an early summer peak in the mesozooplankton biomass. Pelagic productivity, predicted by the LTL model, was highly seasonal with little winter food for the higher trophic levels. The Ecosim model was originally based on the assumption of constant annual inputs of energy and, consequently, when coupled, pelagic species suffered population losses over the winter months. By contrast, benthic populations were more stable (although the benthic linkage modelled was purely at the detritus level, so this stability reflects the stability of the Ecosim model). The coupled model was used to examine long-term effects of environmental change, and showed the system to be nutrient limited and relatively unaffected by forecast climate change, especially in the benthos. The stability of an Ecosim formulation for large higher tropic level food webs is discussed and it is concluded that this kind of coupled model formulation is better for examining the effects of long-term environmental change than short-term perturbations

Ecological values of Hamilton urban streams (North Island, New Zealand): constraints and opportunities for restoration

Urban streams globally are characterised by degraded habitat conditions and low aquatic biodiversity, but are increasingly becoming the focus of restoration activities. We investigated habitat quality, ecological function, and fish and macroinvertebrate community composition of gully streams in Hamilton City, New Zealand, and compared these with a selection of periurban sites surrounded by rural land. A similar complement of fish species was found at urban and periurban sites, including two threatened species, with only one introduced fish widespread (Gambusia affinis). Stream macroinvertebrate community metrics indicated low ecological condition at most urban and periurban sites, but highlighted the presence of one high value urban site with a fauna dominated by sensitive taxa. Light-trapping around seepages in city gullies revealed the presence of several caddisfly species normally associated with native forest, suggesting that seepage habitats can provide important refugia for some aquatic insects in urban environments. Qualitative measures of stream habitat were not significantly different between urban and periurban sites, but urban streams had significantly lower hydraulic function and higher biogeochemical function than periurban streams. These functional differences are thought to reflect, respectively, (1) the combined effects of channel modification and stormwater hydrology, and (2) the influence of riparian vegetation providing shade and enhancing habitat in streams. Significant relationships between some macroinvertebrate community metrics and riparian vegetation buffering and bank protection suggest that riparian enhancement may have beneficial ecological outcomes in some urban streams. Other actions that may contribute to urban stream restoration goals include an integrated catchment approach to resolving fish passage issues, active reintroduction of wood to streams to enhance cover and habitat heterogeneity, and seeding of depauperate streams with native migratory fish to help initiate natural recolonisation

Noise-enabled precision measurements of a Duffing nanomechanical resonator

We report quantitative experimental measurements of the nonlinear response of a radiofrequency mechanical resonator, with very high quality factor, driven by a large swept-frequency force. We directly measure the noise-free transition dynamics between the two basins of attraction that appear in the nonlinear regime, and find good agreement with those predicted by the one-dimensional Duffing equation of motion. We then measure the response of the transition rates to controlled levels of white noise, and extract the activation energy from each basin. The measurements of the noise-induced transitions allow us to obtain precise values for the critical frequencies, the natural resonance frequency, and the cubic nonlinear parameter in the Duffing oscillator, with direct applications to high sensitivity parametric sensors based on these resonators.Comment: 5 pages, 5 figure