Glass eels (Anguilla anguilla) growth in a recirculating system

On a commercial eel farm, which uses a recirculation system, 400,000 glass eels were farmed for a period of 328 days at 20o – 23o C. The physicochemical parameters of the farm water were kept at normal conditions during the experiment. The NO 2 was kept between 1.0 and 3.0 mg/l. By the end of the experiment, 4,582 kg of fish feed were consumed and 2,939 kg of eels were produced (177,523 eels with mean final individual body weight of 16.6g and mean food conversion ratio of 1.625). The glass eels showed a high variability in their capacity to grow

Pollution in the open oceans: 2009-2013

This review of pollution in the open oceans updates a report on this topic prepared by GESAMP five years previously (Reports and Studies No. 79, GESAMP, 2009). The latter report, the first from GESAMP focusing specifically on the oceans beyond the 200 m depth contour, was prepared for purposes of the Assessment of Assessments, the preparatory phase of a regular process for assessing the state of the marine environment, led jointly by the United Nations Environment Programme (UNEP) and the Intergovernmental Oceanographic Commission (UNESCO-IOC)

A new doubly discrete analogue of smoke ring flow and the real time simulation of fluid flow

Modelling incompressible ideal fluids as a finite collection of vortex filaments is important in physics (super-fluidity, models for the onset of turbulence) as well as for numerical algorithms used in computer graphics for the real time simulation of smoke. Here we introduce a time-discrete evolution equation for arbitrary closed polygons in 3-space that is a discretisation of the localised induction approximation of filament motion. This discretisation shares with its continuum limit the property that it is a completely integrable system. We apply this polygon evolution to a significant improvement of the numerical algorithms used in Computer Graphics.Comment: 15 pages, 3 figure

ON THE WIND FLOW PATTERNS UNDER NEUTRAL AND UNSTABLE CONDITIONS IN AN URBAN AREA

thermal behaviour of the materials, e.g., the street floor under the sun and on the geometrical characteristics of the surrounding buildings under low wind conditions. They have a detrimental effect on the stability conditions within and above street canyons, which in turn affect the wind flow patterns and the local air quality. The purpose of the present work is to study experimentally and numerically the flow field developed under neutral and unstable stratification conditions within a typical square urban street canyon. A two-dimensional set up is employed including several canyons in order to simulate an urban environment. Experiments were carried out with the use of a triple hot sensor anemometer upwind above and downwind an isolated building. Measurements were taken under neutral stratification conditions for a wind speed of 3ms-1. Two dimensional numerical simulations have also been conducted for typical urban street canyons. The numerical results have been obtained by the solution of the time averaged Navier-Stokes equations coupled with the standard k-ε turbulence model. The performance of the CFD algorithm is increased by the unstructured Cartesian grid. The numerical code was firstly validated with the experimental results derived under neutral stratification conditions. The effects of stability within a typical urban area were also studied numerically. Spatial distributions of wind velocity, turbulence and pollutants, within street canyons, were analyzed under neutral and unstable conditions for Richardson number Rb=-0.17. Under unstable conditions a great deal of mixing exists within the street canyons. The buoyancy induced flow affects the air exchange between the street canyons and the free surface layer. Vertical air motions extend beyond the level of the street canyons causing instability to increase. It was found, that the stratification effects on the flow can be successfully predicted by the CFD numerical code

Bandwidth allocation in cooperative wireless networks: Buffer load analysis and fairness evaluation.

In modern cooperative wireless networks, the resource allocation is an issue of major significance. The cooperation of source and relay nodes in wireless networks towards improved performance and robustness requires the application of an efficient bandwidth sharing policy. Moreover, user requirements for multimedia content over wireless links necessitate the support of advanced Quality of Service (QoS) features. In this paper, a novel bandwidth allocation technique for cooperative wireless networks is proposed, which is able to satisfy the increased QoS requirements of network users taking into account both traffic priority and packet buffer load. The performance of the proposed scheme is examined by analyzing the impact of buffer load on bandwidth allocation. Moreover, fairness performance in resource sharing is also studied. The results obtained for the cooperative network scenario employed, are validated by simulations. Evidently, the improved performance achieved by the proposed technique indicates that it can be employed for efficient traffic differentiation. The flexible design architecture of the proposed technique indicates its capability to be integrated into Medium Access Control (MAC) protocols for cooperative wireless networks

Macromineral and trace element concentrations and their seasonal variation in milk from organic and conventional dairy herds

To study the effects of dairy production system on milk macromineral and trace element concentrations, milk samples were collected monthly in 2019 from 43 conventional and 27 organic farms. Organic milk contained more Ca (1049.5 vs. 995.8 mg/kg), K (1383.6 vs. 1362.4 mg/kg), P (806.5 vs. 792.5 mg/kg) and Mo (73.3 vs. 60.6 μg/kg) but less Cu (52.4 vs. 60.6 μg/kg), Fe (0.66 vs 2.03 mg/kg), Mn (28.8 vs. 45.0 μg/kg), Zn (4.51 vs. 5.00 mg/kg) and Al (0.32 vs. 1.14 μg/kg) than conventional milk. Significant seasonal variation was observed in all determined minerals’ concentrations. Milk I concentration was not consistently affected by production system, whereas organic milk contained less I in June and July than conventional milk. Dietary factors contributing to different milk mineral concentrations between production systems included intakes of maize silage, dry-straights and oils (higher in conventional diets), and pasture, clover and wholecrop (higher in organic diets)