| 1. |
- Rusydi, A., et al.
(author)
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Metal-insulator transition in manganites: Changes in optical conductivity up to 22 eV
- 2008
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In: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 78:12, s. 125110 (art. no.)-
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Journal article (peer-reviewed)abstract
- The electronic response of doped manganites at the transition from the paramagnetic insulating to the ferromagnetic metallic state in La(1-x)Ca(x)MnO(3) for x=0.3 and 0.2 was investigated by dc conductivity, ellipsometry, and vacuum ultraviolet reflectance for energies between 0 and 22 eV. A stabilized Kramers-Kronig transformation yields the optical conductivity and reveals changes in the optical spectral weight up to 22 eV at the metal-to-insulator transition. In the observed energy range, the spectral weight is conserved within 0.3%. The redistribution of spectral weight in this surprisingly broad energy range has important ramifications for the effective low-energy physics. We discuss the importance of the charge-transfer, Coulomb on-site, Jahn-Teller, and long-range Coulomb screening effects to the electronic structure.
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| 2. |
- Condon, M., et al.
(author)
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Differential sensitivity to surface compliance by tactile afferents in the human finger pad
- 2014
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In: Journal of Neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 111:6, s. 1308-1317
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Journal article (peer-reviewed)abstract
- We undertook a neurophysiological investigation of the responses of low-threshold mechanoreceptors in the human finger pad to surfaces of differing softness. Unitary recordings were made from 26 slowly adapting type I (SAI), 17 fast-adapting type I (FAI), and 9 slowly adapting type II (SAII) afferents via tungsten microelectrodes inserted into the median nerve at the wrist. A servo-controlled stimulator applied ramp-and-hold forces (1, 2, 4 N) at a constant loading and unloading rate (2 N/s) via a flat silicone disc over the center of the finger pad. Nine discs were used, which linearly increased in stiffness across the range. Population responses of the SAI afferents showed the greatest sensitivity to compliance, with a steep monotonic increase in mean firing rate with increasing stiffness (decreasing compliance) of the surface during the loading and plateau (but not unloading) phases. FAI afferents also showed a linear increase in firing during the loading but not unloading phase, although the slope was significantly lower than that of the SAI afferents at all amplitudes. Conversely, SAII afferents were influenced by object compliance only in certain conditions. Given their high density in the finger pads and their linear relationship between firing rate and object compliance during the loading and plateau phases, SAI afferents (together with FAI afferents during the loading phase) are ideally suited to contributing information on surface compliance to the overall estimation of softness, but the SAII afferents appear to play only a minor role.
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