Обнаружено изменение положения и формы линии гистерезиса магнитомодулированного микроволнового поглощения при многократном перемагничивании ВТСП. Смещение сигнала растет с ростом магнитного поля, амплитуды его модуляции и времени сканирования исчезают при Tc, подчиняясь основным закономерностям температурного поведения линии в монокристаллах и в керамике. Появление его коррелирует с достижением критического состояния модулированных экранирующих токов контуров слабых связей, распределенных на поверхности образца, и может быть интерпретировано их взаимодействием в рамках модели обобщенного поверхностного барьера. Наблюдаемая анизотропия указывает на неелевский механизм взаимодействия.

Accurate chromosome segregation during mitotic division of budding yeast depends on the multiprotein kinetochore complex, Dam1 (also known as DASH). Purified Dam1 heterodecamers encircle microtubules (MTs) to form rings that can function as "couplers," molecular devices that transduce energy from MT disassembly into the motion of a cargo. Here we show that MT depolymerization develops a force against a Dam1 ring that is sixfold larger than the force exerted on a coupler that binds only one side of an MT. Wild-type rings slow depolymerization fourfold, but rings that include a mutant Dam1p with truncated C terminus slow depolymerization less, consistent with the idea that this tail is part of a strong bond between rings and MTs. A molecular-mechanical model for Dam1-MT interaction predicts that binding between this flexible tail and the MT wall should cause a Dam1 ring to wobble, and Fourier analysis of moving, ring-attached beads corroborates this prediction. Comparison of the forces generated against wild-type and mutant complexes confirms the importance of tight Dam1-MT association for processive cargo movement under load.

Mitotic chromosomes segregate at the ends of shortening spindle microtubules (MTs). In budding yeast, the Dam1 multiprotein complex supports this dynamic attachment, thereby contributing to accurate chromosome segregation. Purified Dam1 will track the end of a depolymerizing MT and can couple it to microbead transport in vitro. The processivity of such motions has been thought to depend on rings that the Dam1 complex can form around MTs, but the possibility that alternative coupling geometries contribute to these motilities has not been considered. Here, we demonstrate that both rings and nonencircling Dam1 oligomers can track MT ends and enable processive cargo movement in vitro. The coupling properties of these two assemblies are, however, quite different, so each may make a distinct contribution to chromosome motility.