We study the detailed temperature and composition dependence of the resistivity, $\rho(T)$, and thermopower, $S(T)$, for a series of layered bismuth chalcogenides Bi$_2$Te$_{3-x}$Se$_x$, and report the stoichiometry dependence of the optical band gap. In the resistivity of the most compensated member, Bi$_2$Te$_{2.1}$Se$_{0.9}$, we find a low-temperature plateau whose onset temperature correlates with the high-temperature activation energy. For the whole series $S(T)$ can be described by a simple model for an extrinsic semiconductor. By substituting Se for Te, the Fermi level is tuned from the valence band into the conduction band. The maximum values of $S(T)$, bulk band gap as well the activation energy in the resistivity are found for $x \approx 0.9$.

Catalogs project subject field experience onto a multidimensional map which is then converted to a hierarchical list. In the case of the Aarne-Thompson-Uther Tale Type Catalog (ATU), this subject field is the global pattern of tale content defining tale types as canonical motif sequences. To extract and visualize such a map, we considered ATU as a corpus and analysed two segments of it, "Supernatural adversaries" (types 300-399) in particular and "Tales of magic" (types 300-749) in general. The two corpora were scrutinized for multiple motif co-occurrences and visualized by two-mode clustering of a bag-of-motif co-occurrences matrix. Findings indicate the presence of canonical content units above motif level as well. The organization scheme of folk narratives utilizing motif sequences is reminiscent of nucleotid sequences in the genetic code.

Catalogs project subject field experience onto a multidimensional map which is then converted to a hierarchical list. In the case of the Aarne-Thompson-Uther Tale Type Catalog (ATU), this subject f ...

Capsule Waders fed on the most abundant invertebrates: visual foragers preferred nektonic bugs, while tactile foragers had more diverse food preferences.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Ultrafast time-resolved optical absorption has been measured as a function of doping and temperature in Bi2Sr2Ca1-yYyCu2O8 (0<y<1) and YBa2Cu3O7-delta (0.06 < delta < 1). A fast transient response is observed, which changes sign as a function of y in Bi2Sr2Ca1-yYyCu2O8 and delta in YBa2Cu3O7-delta. Careful consideration of the possible mechanisms for the observed behavior leads us to suggest that two independent mechanisms are operating, whereby the two observed positive photoinduced absorption components are due to the electrodynamic response of photoinduced carriers, while the negative signal arises due to spectral hole burning. In the metallic samples a long-lived component is observed, which we suggest comes from photoinduced localized states intrinsic only to the superconducting species of the high-T-c materials. A very significant increase in the scattering rate at temperatures just above T-c signifies coupling to charge and possibly spin fluctuations just above T-c. A large reduction in scattering rate is observed below T-c, similar to that observed previously in YBa2Cu3O6.9 and Tl2Ba2CaCu2O8.

Pressure measurements on successively heat-treated ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ single crystals suggest that the out-of-plane resistivity (${\mathrm{\ensuremath{\rho}}}_{\mathit{c}}$) is diffusive even if d${\mathrm{\ensuremath{\rho}}}_{\mathit{c}}$/dT is positive in high-quality samples. d${\mathrm{\ensuremath{\rho}}}_{\mathit{c}}$/dT>0 comes from the temperature dependence of the in-plane lifetime of the particles which tunnel to the neighboring planes and d${\mathrm{\ensuremath{\rho}}}_{\mathit{c}}$/dT0 is due to phonon-assisted hopping when disorder is introduced between the CuO layers.