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We have measured temperature and magnetic-field dependences of the thermal conductivity of single crystals of the frustrated two-leg spin-ladder system BiCu 2 PO 6 in magnetic fields up to 14 T. It has been found that the temperature dependence of the thermal conductivity along every principal crystallographic axis shows two peaks in zero field but that the magnitude of the thermal conductivity along the b-axis parallel to spin ladders, κ b , is significantly larger than those of the thermal conductivity along the a-axis, κ a , and along the caxis, κ c , at high temperatures above 7 K. These results suggest that the thermal conductivity due to spins probably exists only in κ b . Furthermore, it has been found that both magnetic-field dependences of κ a and κ b at 3 K show kinks at ~ 7 T and ~ 10 T, where the spin state may change.

In order to investigate the spin state of azurite, Cu 3 (CO 3 ) 2 (OH) 2 , we have measured the thermal conductivity along the c-axis,  c , perpendicular to the spin diamond-chains. It has been found that the temperature dependence of  c shows a broad peak at ~ 100 K, which is explained as being due to the strong phonon-scattering by the strong spin-fluctuation owing to the spin frustration at low temperatures below ~ 100 K. Furthermore, it has been found that

Abstract:In evolutionary linguistics, the Iterated Learning Model (ILM) is often used for simulating a first language acquisition. Whereas an infant agent acquires a grammar through communication with his/her parent in ILM, the length of syntax rules tends to increase rapidly over generations due to the addition of symbols of meaningless terminal symbols. In the case learning agents potentially have more than one teacher agent, this problem causes an unnatural learning, which results in a combinatorial explosion. In this paper, we propose a learning method in ILM to solve the problem by string clipping. Our experimental result showed that the length of utterances decreases without potential influence in intergenerational language propagation.

Cu core columns, a cylindrical-shaped copper core material with Ni and solder plating, are attracting attentions as next generation joint material instead of normal solder balls, Cu core balls, and even Cu plating pillars. Cu core columns have the ability to control and maintain a consistent stand-off height, and can achieve remarkable electric and thermal conductivity because of excellent physical properties of Cu. However, it is unclear whether it can be mounted stably like normal solder balls because of its cylindrical shape. Therefore, in this paper, we set our goal to establish Cu Core Column application for next generation bumping material by examining the melting behavior, wettability of Cu core column bumps, and reliability for drop impact and thermal stress.