2,042 research outputs found
Negative Differential Resistance Induced by Mn Substitution at SrRuO3/Nb:SrTiO3 Schottky Interfaces
We observed a strong modulation in the current-voltage characteristics of
SrRuO/Nb:SrTiO Schottky junctions by Mn substitution in SrRuO,
which induces a metal-insulator transition in bulk. The temperature dependence
of the junction ideality factor indicates an increased spatial inhomogeneity of
the interface potential with substitution. Furthermore, negative differential
resistance was observed at low temperatures, indicating the formation of a
resonant state by Mn substitution. By spatially varying the position of the Mn
dopants across the interface with single unit cell control, we can isolate the
origin of this resonant state to the interface SrRuO layer. These results
demonstrate a conceptually different approach to controlling interface states
by utilizing the highly sensitive response of conducting perovskites to
impurities
Hawking radiation of a vector field and gravitational anomalies
Recently, the relation between Hawking radiation and gravitational anomalies
has been used to estimate the flux of Hawking radiation for a large class of
black objects. In this paper, we extend the formalism, originally proposed by
Robinson and Wilczek, to the Hawking radiation of vector particles (photons).
It is explicitly shown, with Hamiltonian formalism, that the theory of an
electromagnetic field on d-dimensional spherical black holes reduces to one of
an infinite number of massive complex scalar fields on 2-dimensional spacetime,
for which the usual anomaly-cancellation method is available. It is found that
the total energy emitted from the horizon for the electromagnetic field is just
(d-2) times as that for a scalar field. The results support the picture that
Hawking radiation can be regarded as an anomaly eliminator on horizons.
Possible extensions and applications of the analysis are discussed.Comment: 14 pages, 1 figur
Self-Assessed Reading Comprehension in English Among Adults in Japan : Implications of Lifestyle and Information Technology
This study commences with statistical data analysis of Japanese adults’ self-assessment of their English reading comprehension and various explanatory variables. Data from the Japanese General Social Survey (JGSS) were analyzed in two stages. In the first stage, a series of bivariate analyses were conducted with demographic, socio-economic, and lifestyle-related indicators as independent variables and self-assessed reading comprehension in English as the dependent variable. In the second stage, several multivariate models were constructed to determine which model best accounts for the effects on the dependent variable. The variables in the category of lifestyle-related factors—which includes the degree of information technology (IT) utilization—surfaced as predictive of the variable on self-assessed reading comprehension in English for Japanese adults. Subsequent to the analyses, implications and possibilities of IT as a reading resource for Japanese adult learners of English are discussed
Time variation of proton-electron mass ratio and fine structure constant with runaway dilaton
Recent astrophysical observations indicate that the proton-electron mass
ratio and the fine structure constant have gone through nontrivial time
evolution. We discuss their time variation in the context of a dilaton runaway
scenario with gauge coupling unification at the string scale . We
show that the choice of adjustable parameters allows them to fit the same order
magnitude of both variations and their (opposite) signs in such a scenario.Comment: 16 pages, 1 figure, to appear in Phys. Rev.
Functional expression of thiocyanate hydrolase is promoted by its activator protein, P15K
AbstractThiocyanate hydrolase (SCNase) is a cobalt-containing enzyme with a post-translationally modified cysteine ligand, γCys131-SO2H. When the SCNase α, β and γ subunits were expressed in Escherichia coli, the subunits assembled to form a hetero-dodecamer, (αβγ)4, like native SCNase but exhibited no catalytic activity. Metal analysis indicated that SCNase was expressed as an apo-form irrespective of the presence of cobalt in the medium. On the contrary, SCNase co-expressed with P15K, encoded just downstream of SCNase genes, in cobalt-enriched medium under the optimized condition (SCNase(+P15K)) possessed 0.86 Co atom/αβγ trimer and exhibited 78% of the activity of native SCNase. SCNase(+P15K) showed a UV–Vis absorption peak characteristic of the SCNase cobalt center. About 70% of SCNase(+P15K) had the γCys131-SO2H modification. These results indicate that SCNase(+P15K) is the active holo-SCNase. P15K is likely to promote the functional expression of SCNase probably by assisting the incorporation of cobalt ion
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