Velocity weakening and possibility of aftershocks in nanofriction experiments

We study the frictional behavior of small contacts as those realized in the atomic force microscope and other experimental setups, in the framework of generalized Prandtl-Tomlinson models. Particular attention is paid to mechanisms that generate velocity weakening, namely a decreasing average friction force with the relative sliding velocity.The mechanisms studied model the possibility of viscous relaxation, or aging effects in the contact. It is found that, in addition to producing velocity weakening, these mechanisms can also produce aftershocks at sufficiently low sliding velocities. This provides a remarkable analogy at the microscale, of friction properties at the macroscale, where aftershocks and velocity weakening are two fundamental features of seismic phenomena.Comment: 8 pages, 7 figure

Dry Friction due to Adsorbed Molecules

Using an adiabatic approximation method, which searches for Tomlinson model-like instabilities for a simple but still realistic model for two crystalline surfaces in the extremely light contact limit, with mobile molecules present at the interface, sliding relative to each other, we are able to account for the virtually universal occurrence of "dry friction." The model makes important predictions for the dependence of friction on the strength of the interaction of each surface with the mobile molecules.Comment: four pages of latex, figure provide

North of the Nullarbor Plain

For a few hardy dingo-trappers—experienced bushmen able and willing to endure the rigours pf a nomadic existence in a waterless country - the area to the north of the Nullabor Plains has long been a favoured watering ground. In the 1949-1950 season bounties were paid on about 3,000 dingo scalps from this area

Cardiopulmonary exercise testing in young people with cystic fibrosis

This is the author accepted manuscript. The final version is available to members only from BASES via the link in this record.First published in The Sport and Exercise Scientist, Vol. 61, p. 22 (Autumn 2019). Published by the British Association of Sport and Exercise Sciences – www.bases.org.u

Wild dog investigations

Following the information gained during the expedition to the north of the Nullabor plains in 1951, which indicated that dogs were moving along well defined leads on to the Plains from the direction of the Warburton Ranges, the Agriculture Protection Board authorised a further expedition by the Vermin Control Branch to endeavor to trace the origin of the migrations. Large sandhills had prevented the Nullabor Plains expedition from following the leads as far north as planned

Dingo destruction—destroying wild dog pups

Quite apart from the heavy financial losses caused in the sheep industry by the depredations of wild dogs (we use the term to cover both the true dingoes and various breeds of domesticated dogs running wild), the ghastly suffering which they cause should make every sheep-owner anxious to destroy these canine scourges wherever an opportunity offers. Wild dogs on killing sprees will maim and kill far more sheep than they can eat, but they cause the greatest suffering when teaching pups to kill. At such times, the adult dogs will disable sheep and leave them till the pups are brought up to inflict further suffering on the helpless victims. This process will be repeated again and again until the pups are able to make their own kills

Wildlife hazards from 1080 baiting

ONE-SHOT oat baiting with sodium fluoroacetate (1080) is a relatively safe method of trail baiting rabbits. The hazard to wildlife is small and every effort is made to further reduce the hazard by selective application of the poison

Rabbit control with 1080

The lower South-West areas have for some time past been regarded as perhaps the most difficult areas in Western Australia from the point of view of rabbit control. The farmer here has to contend with several factors, peculiar to this area, which make his work more difficult. Such obstacles as bracken fern, falling timber, good burrowing soil and a long breeding season combined with small holdings, lack of rabbit control experience, partial use of the cleared areas (tobacco and potato growers) and a low income potential, have rendered the task of rabbit control exceedingly difficult for the average farmer, especially in the Manjimup-Pemberton areas

An exhaust sprayer for grasshopper destruction

Spraying with dieldrin mixtures before the insects reach the flying stage has given excellent results in controlling grasshopper plagues, and the Agriculture Protection Board is supplying dieldrin spraying material free of charge to farmers in the Eastern, North-Eastern and Northern Agricultural Areas

The new approach to rabbit poisoning 1080 and improved methods

The rabbit in Australia has only a relatively short history*, but during that period, of 168 years, has probably done more harm to this country than any other pest. In Western Australia, as in some of the other States, investigations directed towards the improvement of control methods—particularly poisoning—have been intensified over recent years. Although it is recognised that no single method could accomplish eradication or give completely satisfactory control, it is also evident that the improvement of poisoning methods could help greatly. Some of our investigations have been aimed at improving techniques in poisoning procedure and also in finding better poisons. One of the new poisons, 1080 (sodium fluoroacetate) has proved very effective