1,598 research outputs found
Dielectric anomaly in coupled rotor systems
The correlated dynamics of coupled quantum rotors carrying electric dipole
moment is theoretically investigated. The energy spectra of coupled rotors as a
function of dipolar interaction energy is analytically solved. The calculated
dielectric susceptibilities of the system show the peculiar temperature
dependence different from that of isolated rotors.Comment: 5 pages, 4 figures (Figure 2 is available on request from
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Glass-like Thermal-Transport in Symmetry-Broken Clathrates
We present the quantitative interpretation for the glass-like behavior of
thermal conductivities for type-I clathrate compounds involving
off-centered guest ions. It is shown that the dipole-dipole interaction
generated in cage/guest-ion systems is crucial to reproduce the characteristics
of thermal conductivities for these symmetry-broken clathrates. The above
scenario also explains well the difference of between the -type
and the -type -BGS found recently by K. Suekuni et al. [Phys. Rev. B,
77 (2008) 235119.
Retinal adaptation of Japanese common squid (Todarodes pacificus Steenstrup) to light changes
The response of retinae of the Japanese common squid (Todarodes pacificus Steenstrup) was recorded in relation to various light intensities. In the light-adapted eye of common squid, the black pigment ascends to the external limiting membrance of the retina. Conversely, in the dark-adapted eye the black pigment descends toward the center of the black pigment layer. To express the degree of adaptation, the authors give the ratio of the height (thickness) of the black pigment to the total height (thickness) of the retina as a percentage (%)
Phonon-glass electron-crystal thermoelectric clathrates: Experiments and theory
Type-I clathrate compounds have attracted a great deal of interest in
connection with the search for efficient thermoelectric materials. These
compounds constitute networked cages consisting of nano-scale
tetrakaidecahedrons (14 hedrons) and dodecahedrons (12 hedrons), in which the
group 1 or 2 elements in the periodic table are encaged as the so-called
rattling guest atom. It is remarkable that, though these compounds have
crystalline cubic-structure, they exhibit glass-like phonon thermal
conductivity over the whole temperature range depending on the states of
rattling guest atoms in the tetrakaidecahedron. In addition, these compounds
show unusual glass-like specific heats and THz-frequency phonon dynamics,
providing a remarkable broad peak almost identical to those observed in
topologically disordered amorphous materials or structural glasses, the
so-called Boson peak. An efficient thermoelectric effect is realized in
compounds showing these glass-like characteristics. This decade, a number of
experimental works dealing with type-I clathrate compounds have been published.
These are diffraction experiments, thermal and spectroscopic experiments in
addition to those based on heat and electronic transport. These form the raw
materials for this article based on advances this decade. The subject of this
article involves interesting phenomena from the viewpoint of not only physics
but also from the view point of the practical problem of elaborating efficient
thermoelectric materials. This review presents a survey of a wide range of
experimental investigations of type-I clathrate compounds, together with a
review of theoretical interpretations of the peculiar thermal and dynamic
properties observed in these materials.Comment: 51pages, 43 figure
Models of schooling in the global age: the case of Japan
In sum, in Japan today, we see a society that shares many educational trends with the rest of the world (e.g. globalization), while maintaining distinct features of its model of schooling. Some parts of this model have been introduced internationally, while other parts of it are seen as domestic
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