Alpha-Hematite: Stable Remanence and Memory

Abstract

responses are made at 0 during the exposure of the hand when the left eye is used, then this direction of response would be expected to persist without visual guidance after the exposure period.For this experiment the distance RY was 12 cm and that of YP was 25.5 cm. Assuming an interpupillary distance of 6 cm the distance LO was 41.5 cm and OP was 12.5 cm.With feet in a fixed position and head immobilized in a support so that the eyes were 12 cm above the plane of an aperture 9.5 X 7 cm, 12 subjects (group E) were required to make 5 dots directly beneath the marked center without visual guidance before and after an exposure period. The right hand was used throughout. For the kinesthetically controlled centering responses before and after exposure, a cover bearing a central mark coincident with the left-right center of the aperture was placed over the opening and dots were made on the surface below so that they were judged to "be in vertical alignment with the center mark. For the exposure period the cover was removed and the subject now viewed his right hand through the opening with his left eye. The right eye was covered. Thirteen dots, one every 13 seconds, were made on separate sheets of paper so that they were judged to be in vertical alignment with the center. The center was indicated by a line coincident with that on the cover used for the responses betore exposure. Thus in the phases before and after exposure the position beneath the center of the aperture (which was covered) was judged kinesthetically and during the exposure period visual-kinesthetic judgments of the same position were made with only the left eye being used.There were two control conditions. Since maintained motion of a limb in a given direction can result in a sensory spatial aftereffect (3), another 12 subjects (group C1) performed the tasks before and after exposure but during the intervening period the aperture cover was left in place and the limb moved 1130 responses are made at 0 during the exposure of the hand when the left eye is used, then this direction of response would be expected to persist without visual guidance after the exposure period.For this experiment the distance RY was 12 cm and that of YP was 25.5 cm. Assuming an interpupillary distance of 6 cm the distance LO was 41.5 cm and OP was 12.5 cm.With feet in a fixed position and head immobilized in a support so that the eyes were 12 cm above the plane of an aperture 9.5 X 7 cm, 12 subjects (group E) were required to make 5 dots directly beneath the marked center without visual guidance before and after an exposure period. The right hand was used throughout. For the kinesthetically controlled centering responses before and after exposure, a cover bearing a central mark coincident with the left-right center of the aperture was placed over the opening and dots were made on the surface below so that they were judged to "be in vertical alignment with the center mark. For the exposure period the cover was removed and the subject now viewed his right hand through the opening ...

A Possible Source for The Coercivity of Ilmenite-Hematite Minerals

“…Nevertheless the suggestion by Smith and Fuller (1967) attributing the high coercivity of hematite to a defect moment does seem to be supported by low temperature measurements of Kobayashi and Smith (1965). Perhaps both a spin canted and a defect moment originate at, or near, the same temperature (690).…”

“…Moreover Smith and Fuller (1967, Figure 2) have presented evidence that Kawai's thermal curves are not reproducible. Coe (1967) has shown that numerous factors can give rise to such curves (including changes in the Curie or Neel point), i.e.…”

“…Since Smith and Fuller (1967) have given reasons why exchange anisotropy is also inadequate, we are left with magnetostrictive anisotropy as being the only energy capable of producing the observed values. Smith and Fuller (1967) have suggested that the hard coercivity of hematite originates in a defect moment.…”

“…Since Smith and Fuller (1967) have given reasons why exchange anisotropy is also inadequate, we are left with magnetostrictive anisotropy as being the only energy capable of producing the observed values. Smith and Fuller (1967) have suggested that the hard coercivity of hematite originates in a defect moment. Citing the differential thermal analysis of Aharoni et al (1962) Aharoni et al (1963) published an erratum which states that there is only evidence for the existence of one transition (690).…”

The Magnetic Properties of Naturally Occurring Goethite

“…It is believed that this is a result of a few spins without mates so that the cooling process allows the acquisition of TRM. This is probably a simple property of most antiferromagnetic materials as discussed by Smith & Fuller (1967).…”