Dynamics of Vortices in Superconductors Observed by Electron Waves

Although, in electron microscopy, an object is usually observed by using the intensity of an electron beam transmitted through it, the phase distribution of the electron beam also provides different information about the object. It has been difficult, however, to obtain the phase information because of the low coherence of an electron beam. Recent development of a coherent field emission electron beam and related techniques, such as electron holography, has provided a way to observe microscopic objects and fields by precisely measuring the phase information of an electron beam. It has, for example, become possible to observe the dynamics of individual vortices in superconducting thin films

Criterion for Assessing the Big Civilization

This paper is an attempt to establish an objective criterion for civilizations, in order to treat them impartially and give them a fair assessment. First, theories up to the present about civilizations including those of Spengler and Toynbee are introduced. Second, the criterion presented by Bagby to distinguish major civilizations and peripheral civilizations are examined and proved to be subjective. Then the author proposes as an objective criterion for big civilizations just the pattern of succeeding four stages with the span of 400~500 years each. Big civilizations meeting this requirement which total eight or nine are divided into two types according to the difference of their nature. Lastly is shown how four puzzles of world history that have hitherto caused a lot of disputes (feudalism, absolute power of royalty, capitalism and modernization) can be solved through the recognition of these big civilizations

「産屋」再考 : その定説と出産の歴史の交錯

The article argues against the widely held modern understanding of birthing practices in premodern Japan: that birth took place in ubuya, or parturition huts, which were constructed away from the home in order to contain birth-related pollution; that this practice finds its historical origin and authentication in the ancient texts, the Kojiki and Nihon shoki; that the practice was universal and continuous from ancient times through the early twentieth century; and that birthing women, polluted and isolated as they were, were miserable and oppressed. Through the examination of writings from ancient through early modern times, we found that the “ubuya trope” proponents had misread and misinterpreted passages in historical texts. The ubuya in the Kojiki did not connote birth pollution. The term ubuya in aristocratic writings did not refer to an isolated birthing hut. The instances of ubuya that can be observed in early modern times were few and located specifically in coastal and mountainous regions. Moreover, far from turning women into passive victims of an oppressive “tradition,” the ubuya structure sometimes seemed to have met purposes other than giving birth, such as committing infanticide and sexual liaison, and thus invited the warrior government’s censure and order for its removal. Irrespective of ubuya, however, the notion of birth-related pollution developed and expanded in accordance with the evolving power relations of the imperial, aristocratic, religious, and warrior institutions. Not a simple story of female oppression, the actual history of the institution of ubuya points to the misconceived universality in the modernist construction of the “unchanging tradition” and to the need to appreciate women’s agency in giving meanings to their birthing process

Quantum physics - Disturbance without the force

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62558/1/452298a.pd

Domain Nucleation and Annihilation in Uniformly Magnetized State under Current Pulses in Narrow Ferromagnetic Wires

We investigate the current-driven magnetization dynamics in narrow Permalloy wires by means of Lorentz microscopy and electron holography. Current pulses are found to transform the magnetic structure in the uniformly magnetized state below the Curie temperature. A variety of magnetic states including reversed magnetic domains are randomly obtained in low probability. The dynamics of vortices found in most of observed magnetic states seems to play a key role in triggering the magnetization reversal.Comment: 11 pages, 3 figures, 1 video, to appear in Japanese Journal of Applied Physics (Express Letter

Atomic Resolution Electron Holography

It has been demonstrated that electron holography is a very powerful tool to investigate an electromagnetic potential in medium resolution, since the phase of an electron wave is approximately proportional to the potential. Now, electron holography is at the second stage of development: to establish holography at atomic resolution and further to realize Gabor\u27s idea to improve the resolution restricted by the spherical aberration of the objective lens. We investigate the possibility of electron holography to get information at atomic resolution by computer simulations as well as by digital processing of electron holograms. We show that the phase distribution has more resemblance to the specimen structure than the amplitude distribution. We also compare electron holography with electron microscopy from an image processing point of view

Colloidal Dynamics on Disordered Substrates

Using Langevin simulations we examine driven colloids interacting with quenched disorder. For weak substrates the colloids form an ordered state and depin elastically. For increasing substrate strength we find a sharp crossover to inhomogeneous depinning and a substantial increase in the depinning force, analogous to the peak effect in superconductors. The velocity versus driving force curve shows criticality at depinning, with a change in scaling exponent occuring at the order to disorder crossover. Upon application of a sudden pulse of driving force, pronounced transients appear in the disordered regime which are due to the formation of long-lived colloidal flow channels.Comment: 4 pages, 4 postscript figure