A simple model demonstrates that there is no theoretical connection between the extent of price discrimination and the extent of market power. D 2006 Elsevier B.V. All rights reserved.

Mass, an inherent property of matter, is calculated directly for the photon particle from very classical principles kinetic theory gases. That concept mass nearly as old physics itself and in fact nothing prevents this approach to be carried out a so-called quantum particle, not even its minute size. It end result with no perspective nor other outcome. Quite opposite, single ponderable tiny fre...

BACKGROUND There are different street substance users' communities (SSUCs). Typology of SSUCs in Tehran, Iran was approached in this qualitative study. METHODS Using content analysis and saturation principles, 22 street-outreach workers were recruited and interviewed. Data were analyzed using open, axial, and selective coding. FINDINGS Three types of SSUCs were identified. SSUCs were differ...

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