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(2000)Journal ArticleBi1.7Pb0.3Sr2Ca2Cu3O10+y was used as an example of Cuprates for our study. The subtle thermal transitions and the jumps of the parameters appear in the sample at about 300 and 700oC, respectively. The unit cell of the sample is composed of two structural blocks: perovskite and rock salt. The size of every block along c direction is about a nanometer. What should be made clear is whether the two thermal and structural changes take place in the whole cell or from different blocks. The bond lengths in the unit cell are analyzed carefully before and after two thermal and structural changes based on the results of X-ray diffraction. Careful analysis of the bond length in the samples demonstrates that the two jumps of the parameters are correlated with the two blocks. After the jump at about 300oC, the bond lengths in the rock salt block change more significant than in the perovskite block. After the jump at about 700oC, the bond lengths in the perovskite block change more significant than in the rock salt block. The change of the bond lengths clearly shows that the different thermal transitions and the jumps of the parameters take place in different blocks.
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(1999)Journal ArticleThe influence of the flux flow on a.c. loss and magnetic penetration process in superconductors has been investigated. Asymptotic solutions of magnetic and electric fields and a.c. loss are presented in the form of a power series of [Lambda], the normalized frequency of the external a.c. magnetic field. The results show that the flux flow retards the response of inner magnetic field to the external one, which results in a deviation from the critical state model and a non-hysteretic loss. In the cases of H0>Hp, the deviation from the critical state is in the order of the second power of [Lambda]. The induced electric field and the macro-penetration depth are decreased by the slowdown of the flux movement, giving a negative contribution to the a.c. loss. However, the negative contribution is compensated by the increase of the current density, leading to a net increase of the a.c. loss. As a result, the a.c. loss exhibits a positive dependence on the frequency and the amplitude of the external magnetic field.
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(1999)Journal ArticleLow-temperature thermal expansion and its correlation with oxygen nonstoichiometry have been studied for Bi1.7Pb0.3Sr2Ca2Cu3O10+y samples. An anomalously big jump of the thermal expansion in the c direction of Bi1.7Pb0.3Sr2Ca2Cu3O10+y has been observed at a temperature slightly above the superconductivity transition temperature. The corresponding temperature and the magnitude of the jump are found to be correlated with the oxygen nonstoichiometry, carrier concentration and superconductivity. The results reveal that the anomalously big jump of the thermal expansion is an electron-assisted lattice softening transition. Its correlation with the superconductivity suggests that phonon-electron interaction still plays a certain role in the superconductivity in high-Tc cuprates.
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(2006)Journal ArticleTwo models that predict perceived timbrai brightness in terms of the centroid of the frequency spectrum were investigated. One model simply uses the centroid of the frequency spectrum, the other divides this same value by the fundamental frequency: the latter scales the centroid of the frequency spectrum with the fundamental frequency. Different single tone and pitch combinations, presented sequentially, were compared. Participants were not asked to ignore pitch differences and intervals of greater than an octave were compared. The results indicate that brightness is much better correlated with frequency spectrum centroid (r = 0.513, p less than or equal 0.01) than with the ratio of the centroid of the frequency spectrum to the fundamental frequency (r = 0.030. p = 0.441).
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(1998)Journal Article
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(1998)Journal ArticleThe vortex-glass-liquid transition in Bi---Sr---Ca---Cu---O (BSCCO) intergrowth single crystals in which some CuO2 trilayers are inserted into the Bi2Sr2CaCu2O8 matrix has been studied. The curvature of the log V-logI curves for CuO2 trilayers is found to change from negative to positive with increasing magnetic field and a scaling behaviour for the vortex-glass state is observed. The magnetic field dependence of the vortex-glass transition temperature, TG, qualitatively obeys the relation H(TG) (Tc − Tg)2v0, with v0 = 1.15 ± 0.2, which is larger than the 2/3 predicted theoretically for an isotropic 3D system. Our results reveal that the vortex-glass transition exists in a system constructed with CuO2 trilayers.
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(2008)Journal ArticleTo reconstruct an indigenous language known solely from historical wordlists, the linguist needs to decide which source wordlists are most relevant, i.e. which sources are most likely to be attestations of the language to be reconstructed. There is little published research on methods appropriate to this task, and yet there is increasing attention to indigenous language reconstruction in support of language revival and revitalisation in education and community contexts. This paper describes a replicable and relatively objective method for comparing lexical similarity within a set of historical sources. The method described draws on the use of measures of lexical similarity in linguistics and the use of measures of endemism in biogeography. The method is illustrated via an analysis of historical sources for Aboriginal languages from the greater Sydney region, New South Wales, Australia.
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(2010)Journal ArticleIn 2005, 60 health care workers were recruited through services that attract injecting drug users (IDUs) and asked to complete attitude measures regarding IDU clients. Mediation analyses indicated that conservative health care workers displayed more negative attitudes toward their IDU clients because they believe that injecting drug use is within the control of the IDU. Negative attitudes toward IDU clients, in turn, were associated with worry about IDU clients' behavior in the clinic and with beliefs that IDU clients should disclose their hepatitis C status to their health care worker. Perceptions of controllability of drug use were also associated with the belief that IDU clients' ailments were caused by their IDU status. The study's limitations are noted.
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