Ocular abnormalities in Whippets practicing lure coursing in Poland.

Coursing is a canine sport discipline invented for sighthounds. The dogs chase the mechanically operated lure on an open area at the track that consists of straight lines as well as turns. Thus, the dogs must rely mainly on their sight in order to chase the lure and to compete. Whippets are the most popular sighthound breed in Poland and more and more dogs practice lure coursing on professional level. Several ocular disorders are known or presumed to be inherited in Whippets, so we decided to check how often they occur amongst competing dogs and if they have any impact on the results during competitions. Forty-five regularly competing Whippets underwent complete ophthalmic examination, including evaluation of menace response, pupillary light reflex and dazzle reflex, biomicroscopic examination conducted before and after dilating pupils with topical tropicamide and fundus examination with indirect ophthalmoscopy. Refractive state of each eye was assessed via streak retinoscopy. Ocular abnormalities were identified in 24 dogs (53.3%). The most common finding was vitreous degeneration identified in 9 dogs (20%), five dogs presented multiple lesions. There were no statistically significant differences regarding sex, age, and ranking points between the dogs with and without lesions. However, some of the identified lesions are likely to progress, so we postulate that the ophthalmological examination should receive more attention in sport Whippets, to check if it has any impact on competing dogs at more advanced age.

Asymmetric hysteresis loops of systems of bistable nanoscopic wires.

A system of bistable magnetic nanowires of diameter D = 57 nm, length L = 115 nm, magnetization M = 370 emu/cm3 is simulated. The probability distribution of the switching fields of the wires is Gaussian, with mean Hs = 710 Oe and standard deviation u(Hs) = 105 Oe. The wires are randomly distributed on a plane, with directions parallel (OX) or perpendicular (OY) to the axis direction where the magnetic field is applied. The magnetostatic interaction between the wires leads to an asymmetry of the hysteresis loop of the system. Namely, we obtain different curves M(H) for ascending and descending magnetic field. This behaviour is due to the wires which are perpendicular to the applied magnetic field. The directions of their magnetic moments remain often unchanged during the hysteresis experiment, and their contribution to the magnetic moment measured along OX is equal to zero. However, they interact with the wires parallel to the field, and this interaction influences the magnetic state of the parallel wires. The effect can be useful when we are interested in tailoring the shape of the hysteresis loop. Also, a given magnetic configuration of the wires parallel to OY produces a unique asymmetry of the hysteresis loop of the wires parallel to OX. Once an additional field is applied along OY, this unique state is destroyed. The effect can be useful for safety systems.