Observations on the aurora, by C. S. Wright ....

Abstract

It is unfortunate that drawings were not made on each occasion the aurora was seen, the lack of diagrams greatly increasing the difficulty of working up the results. In all that follows, unless it is specifically stated to be otherwise, the times are those of the 180th meridian and the directions are astronomical. The position of Cape Evans Winter Quarters is Latitude 77 38' 24" S., Longitude 166 24' 7" E., so that time of the 180th meridian is approximately 54 minutes in advance of local time. Hours are numbered from 1 to 24, 1 hour being, therefore, approximately the time at which the sun was due south from the station. The magnetic declination at Cape Evans was about 154| East and the dip about 86 26'. A typical example of the changes in aurora seen at Cape Evans is furnished by the auroral observations of May 1st to May 3rd. The general course of the variations during that period was as follows : May 1st. From 1 hour to 6 hours, no aurora was seen at the exact hours, though the sky was clear. A faint cloud-like patch was, however, seen between North and North 20 East at an altitude of 8, at 4.10 a.m. At 7 hours, faint streamers were observed between N.E. and S.E., rising to an altitude of 35. Observations were discontinued until 22 hours, when an incomplete arch, broken in the centre, was seen to extend from S.W. by S. to E.N.E. The arch was faint, the maximum altitude being about 50. At 23 hours, the aurora was still faint, in the form of a discontinuous arch of maximum altitude 20, extending from E.N.E. to S.S.E. At 23.55, the aurora was bright, in the form of three parallel arches extending from S.W. by S. to N.W. by N. almost across the zenith. These arches gradually coalesced and moved N.W. across the zenith, developing folds. The maximum brightness occurred just before crossing the zenith at 0.04 on May 2nd. There was little motion of detail and no colour could be seen. Unsuccessful attempts were made to take photographs at this time. May 2nd. The aurora was very faint at 0.18, the eastern limb at this time having moved round to north, the western limb remaining stationary. At the same time, a low faint arch of 10 altitude was seen between N.N.W and W. The aurora at 1 hour was in the form of a single, broad, ill-defined arch extending across the zenith from North to S. by W. At 1.30, three broad, parallel, hazy bands were seen in the western hemisphere, of which the uppermost extended from North to S.S.W. across the zenith, and the lowermost was at an altitude of 30 at its maximum. At 2 hours, the only aurora visible was a very faint hazy patch of light in the S.S.W. No aurora was seen at 3 hours and 4 hours, but at 4.07 a rather taint band (moderately bright in places), with little motion, was seen to extend Irom X.X.W. to S.E. At 5 and 6 hours, no aurora was seen, but clouds were visible in the north. At 7 hours, faint patches of light were seen due East, at an altitude of 30. No observations were then recorded during the bright portion of the clay, but, at 19 and 20 hours, the sky was clear, no auror...

An effective rotational mating scheme for inbreeding reduction in captive populations illustrated by the rare sheep breed Kempisch Heideschaap

“…Breeding schemes within flocks that reduce inbreeding were already investigated by Wright (1921 and1938). Kimura and Crow (1963) suggested MAI.…”

“…Typically, each individual is replaced by one of its offspring only, and mated to an individual from a different family (e.g. Wright, 1921;Farid et al, 1987;Sanchez et al, 2003). The rotational mating schemes discussed here function at the (sub)population level rather than at the individual level.…”

Management of genetic diversity in small farm animal populations

“…The simplest way to implement the criterion, above, is to ban the matings beyond a specific degree of relatedness; for example, full sibs, which is a common practice in most breeding programmes. Wright (1921) was the first to propose mating the least related individuals in populations under regular system, a method known as Maximum Avoidance of Inbreeding (MAI). Similarly, in a population of any size and structure, the strategy becomes the 'minimum coancestry mating' design (Nieto et al, 1986), which uses optimisation techniques to identify the scheme that yields the minimum global coancestry between couples.…”

Mating animals by minimising the covariance between ancestral contributions generates less inbreeding without compromising genetic gain in breeding schemes with truncation selection

“…E-mail: mhe@dansksvineproduktion.dk inbreeding is minimum-coancestry mating (Caballero et al, 1996;Meuwissen, 2007). Minimum-coancestry mating pairs the parents by minimising the average coancestry of the individual matings (Wright, 1921).…”