The effect of tyres and a rubber track at high axle loads on soil compaction-Part 2: Multi-axle machine studies

This paper reports on a study of the effect of the passage of multi-axle harvesting machines on the soil physical properties. In particular, it investigates the effect of the rear tyre of a combine harvester on the amount of soil compaction subsequent to the passage of the front tyre/track. The work was conducted in controlled laboratory conditions to determine the effect of a simulated self-propelled combine harvester with a total machine weight of 30–33 t. This was assessed by embedding talcum powder tracer lines in the soil to measure soil displacement and soil density changes. Dry bulk density and penetrometer resistance were also measured. The results showed that the benefit of the rubber track found by Ansorge and Godwin [2007a. The effect of tyres and a rubber track at high axle loads on soil compaction: Part 1: Single Axle Studies. Biosystems Engineering 98 (1), 115–126] was maintained after the additional passage of the rear tyre. After the passage of a track the effect of rear tyre size was insignificant, but the rear tyre size had a significant influence on soil density when following a leading tyre. This was due to a higher strength layer at the soil surface created by the track which was able to withstand the load of the subsequent passes and protect the soil below from further compaction. Results similar to those found for a tracked machine were also achieved by three passes of a 900 mm section width tyre at 5 t load and 0.5 bar inflation pressure. The track results for the 33 t machine were very similar to those of a smaller combine harvester with a total load of 11 t and similar rut width. The study confirmed the benefit of tracks with regard to soil compaction and emphasised the fact that total axle loads and machine weights are less important than how the loads are distributed to the soil

Oceanographic observations of eddies impacting the Prince Edward Islands, South Africa

The ecosystem of the isolated Prince Edward Islands, south of the African continent, is strongly impacted by ocean eddies that are associated with the eastward flowing Antarctic Circumpolar Current. Satellite altimetry has revealed that the archipelago lies in a region of enhanced eddy kinetic energy. In the late 1990s it became apparent that in order to understand the influence of these eddies on the islands' ecosystem, the source, trajectory and nature of these eddies needed to be studied and understood. To this end a special research project with a strong ocean-going component was designed, the DEIMEC (Dynamics of Eddy Impact on Marion's ECosystem) programme. In this review we focus on the physical oceanography and summarize the aims, the results and the successes of this South African research initiative. In the vicinity of the Prince Edward Islands, an average of three intense well-defined eddies is observed per year. Their advection speeds are of the order of a few kilometres per day and longevities of 7-11 months. These features, of c. 100 km in diameter and reaching depths of at least 1000 m, transport anomalous water masses across the Polar Frontal Zone

Two new Lower Cretaceous hymenopterous insects (Insecta: Hymenoptera) from Sierra del Montsec, Spain

Two new hymenoterans are described from the Lower Barremian lithographic limestones of Sierra del Montsec (Lleida, Spain), Leridatoma pulcherrimapulcherima n.gen., n.sp. (Xyelotomidae RASNITSYN, 1968) that combines the most and the least advanced character states in the family (in structure of antenna and fore wing RS, respectively), and Cretephialtites pedrerae n.gen., n.sp. (Ephialtitidae HANDLIRSCH, 1906)

Identity of Prosepididontus calpterys Handlirsch 1920 (Insecta: Grylloblattida: Geinitziidae)

Prosepididontus calopteryx HANDLIRSCH 1920, from the upper Lower Jurassic of Germ a ny, is transferred from Trichoptera to Grylloblattida: Geinitziidae. The anal loop like structure of Prosepididontus calopteryx is built of the concave CuP and two anal veins. Prosepididontidae HANDLIRSCH, 1920 is synonymised under Geinitziidae HANDLIRSCH, 1906

Forward-Backward Multiplicity Correlations in Au+Au Collisions at sNN\sqrt{s_{NN}} = 200 Gev

The study of correlations among particles produced in different rapidity regions may provide understanding of the mechanisms of particle production. Correlations that extend over a longer range are observed in hadron-hadron interactions only at higher energies. Results for short and long-range multiplicity correlations (Forward-Backward) are presented for Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The growth of long range correlations are observed as a function of the pseudorapidity gap in central Au+Au collisions. The Dual Parton model and Color Glass Condensate phenomenology have been explored to understand the origin of long range correlations.Comment: 8 pages, 4 figures, IWCF06, Hangzhou, China, Nov. 21-24, 200

Two new Lower Cretaceous hymenopterous insects (Insecta: Hymenoptera) from Sierra del Montsec, Spain

Two new hymenoterans are described from the Lower Barremian lithographic limestones of Sierra del Montsec (Lleida, Spain), Leridatoma pulcherrimapulcherima n.gen., n.sp. (Xyelotomidae RASNITSYN, 1968) that combines the most and the least advanced character states in the family (in structure of antenna and fore wing RS, respectively), and Cretephialtites pedrerae n.gen., n.sp. (Ephialtitidae HANDLIRSCH, 1906)

Identity of Prosepididontus calpterys Handlirsch 1920 (Insecta: Grylloblattida: Geinitziidae)

Prosepididontus calopteryx HANDLIRSCH 1920, from the upper Lower Jurassic of Germ a ny, is transferred from Trichoptera to Grylloblattida: Geinitziidae. The anal loop like structure of Prosepididontus calopteryx is built of the concave CuP and two anal veins. Prosepididontidae HANDLIRSCH, 1920 is synonymised under Geinitziidae HANDLIRSCH, 1906.Prosepididontus calopteryx HANDLIRSCH 1920, from the upper Lower Jurassic of Germ a ny, is transferred from Trichoptera to Grylloblattida: Geinitziidae. The anal loop like structure of Prosepididontus calopteryx is built of the concave CuP and two anal veins. Prosepididontidae HANDLIRSCH, 1920 is synonymised under Geinitziidae HANDLIRSCH, 1906

The Conrad Rise as an obstruction to the Antarctic Circumpolar Current

The Antarctic Circumpolar Current (ACC) carries water freely around the whole continent of Antarctica, but not without obstructions. Some, such as the Drake Passage, constrict its path, while others, such as mid-ocean ridges, may induce meandering in the current's cores and may cause the genesis of mesoscale turbulence. It has recently been demonstrated that some regions that are only relatively shallow may also have a major effect on the flow patterns of the ACC. This is here shown to be particularly true for the Conrad Rise. Using the trajectories of surface drifters, altimetry and the simulated velocities from a numerical model, we show that the ACC bifurcates at the western side of this Rise. In this process it forms two intense jets at the two meridional extremities of the Rise with a relatively stagnant water body over the Rise itself. Preliminary results from a recent cruise provide compelling support for this portrayal

Surface drift at the western edge of the Agulhas Bank

The Agulhas Bank is a wide continental shelf that forms the southern tip of the African continent. On the eastern side of this shelf the flow of water is dominated by the adjacent Agulhas Current. On its western border, the movement is more complex. It is influenced by the Benguela Current, by the occasional presence of products from the Agulhas Current such as Agulhas rings, Agulhas filaments and by lee eddies. Understanding the flow on this western side of the Agulhas Bank is of considerable ecological importance because it has been assumed that a shelf edge jet carries immotile or weakly motile fish larvae and eggs from the spawning region on the bank to the biologically productive regions of the Benguela upwelling regime. We have used the tracks of a set of surface drifters to study the movement at the western edge of the bank, and show that on average the movement is indeed equatorward along this shelf edge, but that this movement is not persistent in direction or magnitude. Instead, this movement appears to be driven entirely by mesoscale turbulence created at the termination of the Agulhas Current