Onset of magnetism in B2 transition metals aluminides

Ab initio calculation results for the electronic structure of disordered bcc Fe(x)Al(1-x) (0.4<x<0.75), Co(x)Al(1-x) and Ni(x)Al(1-x) (x=0.4; 0.5; 0.6) alloys near the 1:1 stoichiometry, as well as of the ordered B2 (FeAl, CoAl, NiAl) phases with point defects are presented. The calculations were performed using the coherent potential approximation within the Korringa-Kohn-Rostoker method (KKR-CPA) for the disordered case and the tight-binding linear muffin-tin orbital (TB-LMTO) method for the intermetallic compounds. We studied in particular the onset of magnetism in Fe-Al and Co-Al systems as a function of the defect structure. We found the appearance of large local magnetic moments associated with the transition metal (TM) antisite defect in FeAl and CoAl compounds, in agreement with the experimental findings. Moreover, we found that any vacancies on both sublattices enhance the magnetic moments via reducing the charge transfer to a TM atom. Disordered Fe-Al alloys are ferromagnetically ordered for the whole range of composition studied, whereas Co-Al becomes magnetic only for Co concentration >0.5.Comment: 11 pages with 9 embedded postscript figures, to be published in Phys.Rev.

Do horses recognize the difference between harsh tones and soothing tones when using voice as a reinforcer for learning a frightening task

When working with horses, it is frequently asserted that horses have an inherent understanding of harsh voice cues that would be used as reprimands versus soothing voice cues that may be used as positive reinforcers/calming modifiers. If horses are unable to understand this difference, handlers often make poor assumptions that potentially lead to unfair training. A total of 95 horses from 4 different locations in US and Europe were randomly assigned to either soothing voice treatment (SV; n=52) or harsh voice treatment (HV; n=43). The learning task involved horses of various breeds and ages learning to cross a tarpaulin. Methodology was standardised across locations. SV involved handlers saying \u201cgood horse\u201d in a soft, soothing manner whenever horses made forward progress toward the tarpaulin. HV involved saying \u201cquit it\u201d in a loud, harsh manner whenever horses made forward progress toward the tarpaulin. PRAAT software was used to assess similarities in vocal spectrograms of different handlers/treatments. Mean pitch for SV was 244.4\ub13.11 Hz and 275.1\ub12.01 Hz for HV; both well within the equine hearing range. Average intensity (loudness) for SV was 42.3\ub11.04 dB and 56.0\ub11.80 for HV. Contrary to our hypotheses, risk of failing the task (> 10 min to cross the tarpaulin for the 1st time) was not different between treatments (25% failures SV; 25.5% failures HV; p=0.55). Also, for those horses who did cross the tarpaulin, the total time to achieve calmness criterion (crossing with little/no obvious anxiety) did not differ between treatments (157.3\ub159.8 sec HV vs 245.8\ub143.5 SV, p=0.23. A breed difference was noted: Hot bloods=606.8\ub1145.9 sec vs Warm bloods=120.7\ub118.3 sec, p<0.01. Polar heart rate monitors were used on 68 horses. There was no difference between average HR of horses who crossed (84.7\ub13.9 bpm) vs those who failed (82.1\ub15.1) p=0.69. There was also no difference between HV horses (85.4\ub14.8 bpm) and SV horses (81.3\ub14.2) p=0.52