955 research outputs found
Field-induced charge transport at the surface of pentacene single crystals: a method to study charge dynamics of 2D electron systems in organic crystals
A method has been developed to inject mobile charges at the surface of
organic molecular crystals, and the DC transport of field-induced holes has
been measured at the surface of pentacene single crystals. To minimize damage
to the soft and fragile surface, the crystals are attached to a pre-fabricated
substrate which incorporates a gate dielectric (SiO_2) and four probe pads. The
surface mobility of the pentacene crystals ranges from 0.1 to 0.5 cm^2/Vs and
is nearly temperature-independent above ~150 K, while it becomes thermally
activated at lower temperatures when the induced charges become localized.
Ruling out the influence of electric contacts and crystal grain boundaries, the
results contribute to the microscopic understanding of trapping and detrapping
mechanisms in organic molecular crystals.Comment: 14 pages, 4 figures. Submitted to J. Appl. Phy
The human glutathione S-transferase P1-1 gene: modulation of expression by retinoic acid and insulin
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Partnerships and Public Service: Normative Issues for Journalists in Converged Newsrooms
As media companies test and implement newsroom “convergence,” growing numbers of journalists are producing content not only for their own employer but also for other media outlets with which that employer has a business relationship. This article, based on case studies in four converged news markets, explores journalists’ perceptions of normative pressures in this new media environment, particularly in relation to the overarching concept of public service. The findings suggest that although journalists do not see convergence itself as posing significant ethical problems, they do raise concerns related to specific components of public service, including a devotion to accuracy, an avoidance of sensationalism, and independence from economic pressures
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