203 research outputs found
Magnetoelectric ordering of BiFeO3 from the perspective of crystal chemistry
In this paper we examine the role of crystal chemistry factors in creating
conditions for formation of magnetoelectric ordering in BiFeO3. It is generally
accepted that the main reason of the ferroelectric distortion in BiFeO3 is
concerned with a stereochemical activity of the Bi lone pair. However, the lone
pair is stereochemically active in the paraelectric orthorhombic beta-phase as
well. We demonstrate that a crucial role in emerging of phase transitions of
the metal-insulator, paraelectric-ferroelectric and magnetic disorder-order
types belongs to the change of the degree of the lone pair stereochemical
activity - its consecutive increase with the temperature decrease. Using the
structural data, we calculated the sign and strength of magnetic couplings in
BiFeO3 in the range from 945 C down to 25 C and found the couplings, which
undergo the antiferromagnetic-ferromagnetic transition with the temperature
decrease and give rise to the antiferromagnetic ordering and its delay in
regard to temperature, as compared to the ferroelectric ordering. We discuss
the reasons of emerging of the spatially modulated spin structure and its
suppression by doping with La3+.Comment: 18 pages, 5 figures, 3 table
Neutrinos in a gravitational background: a test for the universality of the gravitational interaction
In this work we propose an extended formulation for the interaction between
neutrinos and gravitational fields. It is based on the parametrized
post-Newtonian aproach, and includes a violation of the universality of the
gravitational interaction which is non diagonal in the weak flavor space. We
find new effects that are not considered in the standard scenario for violation
of the equivalence principle. They are of the same order as the effects
produced by the Newtonian potential, but they are highly directional dependent
and could provide a very clean test of that violation. Phenomenological
consequences are briefly discussed.Comment: 18 pages, revtex, no figure
Реализация интегративного подхода при изучении дисциплины "Патологическая физиология" в медицинском университете
МЕДИЦИНСКИЕ ВУЗЫМЕДИЦИНСКИЕ ИНСТИТУТЫОБРАЗОВАНИЕ МЕДИЦИНСКОЕПЕДАГОГИЧЕСКИЕ ТЕХНОЛОГИИОБРАЗОВАТЕЛЬНЫЙ ПРОЦЕССУЧЕБНЫЕ ДИСЦИПЛИНЫМЕЖДИСЦИПЛИНАРНЫЕ СВЯЗИМЕЖДИСЦИПЛИНАРНАЯ ИНТЕГРАЦИЯИНТЕГРАТИВНЫЙ ПОДХОДПАТОФИЗИОЛОГИЯ (ДИСЦИПЛИНА)ПАТОЛОГИЧЕСКАЯ ФИЗИОЛОГИЯ (ДИСЦИПЛИНА)ОБУЧЕНИЕ /МЕТОДЫПРЕПОДАВАНИЕМОТИВАЦИ
A Tale of Two Congresses: The Psychological Study of Psychical, Occult, and Religious Phenomena, 1900-1909
© 2014 Wiley Periodicals, Inc. In so far as researchers viewed psychical, occult, and religious phenomena as both objectively verifiable and resistant to extant scientific explanations, their study posed thorny issues for experimental psychologists. Controversies over the study of psychical and occult phenomena at the Fourth Congress of International Psychology (Paris, 1900) and religious phenomena at the Sixth (Geneva, 1909) raise the question of why the latter was accepted as a legitimate object of study, whereas the former was not. Comparison of the Congresses suggests that those interested in the study of religion were willing to forego the quest for objective evidence and focus on experience, whereas those most invested in psychical research were not. The shift in focus did not overcome many of the methodological difficulties. Sub-specialization formalized distinctions between psychical, religious, and pathological phenomena; obscured similarities; and undercut the nascent comparative study of unusual experiences that had emerged at the early Congresses
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