A recent wave of popular and scholarly discourse has hailed the arrival of the Web 2.0, marking a new generation of Internet users who share and collaborate on popular social networking sites such as MySpace and user‐generated communities such as YouTube and Wikipedia. Social and cultural critics have attempted to take stock of the implications of these various technological changes with specific emphasis on the state of knowledge in contemporary society. This article aims to theoretically examine knowledge in the context of new media technologies with particular attention paid to the notion of “reflexivity.” Focusing on the work of Scott Lash, whose theory of reflexivity radically differs from various other interpretations, I suggest that knowledge, in its modern formulation—as reasoned, stable, and linear—must be rethought for the information age, critiquing some of the predominant scholarly and popular media criticisms that suggests media to be mere enhancements of human forms of communication, knowledge, and sense‐making. I conclude by considering some of the ontological dimensions of the transformations in the dynamics of knowledge in new media technologies.

No abstract

No abstract

Water diffusion-coefficient mapping was used in conjunction with 19 F inversion-recovery echo-planar imaging (IR-EPI) of a sequestered perfluorocarbon (PFC) emulsion to investigate the spatial correlation between the diffusion coefficient of water and the tissue oxygen tension (pO 2 ) in radiation-induced fibrosarcoma (RIF-1) tumors (n = 11). The diffusion-time-dependent apparent diffusion coefficient, D(t), was determined by acquiring diffusion coefficient maps at 20 different diffusion times. Maps at four representative time points in different regions of the D(t) curve were selected for final analysis. An intravenously administered PFC emulsion, perfluoro-15-crown-5-ether, was used to generate the pO 2 maps. D(t) and pO 2 data were acquired with the animal breathing either air or carbogen (95% O 2 -5% CO 2 ) to investigate the effects of increased tumor pO 2 on D(t). The average increase in tumor pO 2 was 22 torr when the breathing gas was changed from air to carbogen. Correlation plots generated from pixel data for D(t) (air breathing) vs D(t) (carbogen breathing) show little deviation from a slope of unity. Correlation plots of D(t) vs pO 2 indicate that no correlation is present between these two parameters. This study also confirmed that necrotic tissue was best differentiated from viable tumor tissue based on D(t) maps at long diffusion times. . †Abbreviations used: ADC, apparent diffusion coefficient; D eff , the constant value of the ADC measured at long diffusion times; D(t), diffusion-time dependent apparent diffusion coefficient; D(t)_a, diffusion-time dependent apparent diffusion coefficient with the animal breathing air; D(t)_c, diffusion-time dependent apparent diffusion coefficient with the animal breathing carbogen; H and E, Hematoxylin and Eosin; IR-EPI, Inversion Recovery Echo Planar Imaging; M 0 , proton spin density; PFC, perfluorocarbon; pO 2 , tissue oxygen tension; pO 2 _a, tissue oxygen tension with the animal breathing air; pO 2 _c, tissue oxygen tension with the animal breathing carbogen; RIF, radiation induced fibrosarcoma; S/V, ratio of surface area to volume; T, tortuosity. Contract/grant sponsor: The Whitaker Foundation.

No abstract