The blurring boundaries between synchronicity and asynchronicity:new communicative situations in work-related Instant Messaging

Instant messaging is one of the most popular communication technologies in virtual teams, enabling interactions to intertwine whole working days, thus creating the sense of copresence for team members who are geographically dispersed. Through close linguistic analyses of naturally occurring data from a virtual team, this article discusses the implications of two novel communicative situations enabled by instant messaging: presence information and the persistence of transcript. The preliminary findings of this study indicate that these new communicative situations require the flouting or rethinking of previously existing interactional norms and that communicative practices employed by the team members are not yet conventionalized/normalized, the expectations and interpretations of interactional rituals and timing vary highly, even within the same virtual team

Modeling Cryptosporidium spp. Oocyst inactivation in bubble-diffuser ozone contactors

CIVINS (Civilian Institutions) Thesis documentThe CT concept (product of disinfectant concentration and characteristic contact time) is currently used to demonstrate compliance with disinfection requirements for Giarda lamblia (G. lamblia) and viruses under the Surface Water Treatment Rule (SWTR). Minimum CT requirements include large safety factors to account for possible deviations from actual disinfection efficiencies achieved in full-scale contactors. The application of this conservative regulatory approach for Cryptosporidium parvum (C. parvum) might result in unrealistic disinfection requirements under the Enhanced SWTR due to the much stronger resistance of this protozoan parasite to inactivation by all chemical disinfectants used in drinking water applications. There is a need for the development of approaches that could provide a more accurate assessmant of actual inactivation efficiency achieved in disinfection contactors. The main objective of this study is to develop and apply a mathematical model predicting the inactivation of Cryptosporidium app. (C. parvum and C. muris) oocysts in ozone bubble-diffusers contactors. The model is calibrated with semi-batch kinetic data, verified with pilot-scale inactivation experiments, and used for predicting and optimizing full-scale disinfection efficiency.http://archive.org/details/modelingcryptosp1094537776US Navy (USN) autho

Determination of Pyrimidine Dimers in Escherichia coli and Cryptosporidium parvum during UV Light Inactivation, Photoreactivation, and Dark Repair

UV inactivation, photoreactivation, and dark repair of Escherichia coli and Cryptosporidium parvum were investigated with the endonuclease sensitive site (ESS) assay, which can determine UV-induced pyrimidine dimers in the genomic DNA of microorganisms. In a 99.9% inactivation of E. coli, high correlation was observed between the dose of UV irradiation and the number of pyrimidine dimers induced in the DNA of E. coli. The colony-forming ability of E. coli also correlated highly with the number of pyrimidine dimers in the DNA, indicating that the ESS assay is comparable to the method conventionally used to measure colony-forming ability. When E. coli were exposed to fluorescent light after a 99.9% inactivation by UV irradiation, UV-induced pyrimidine dimers in the DNA were continuously repaired and the colony-forming ability recovered gradually. When kept in darkness after the UV inactivation, however, E. coli showed neither repair of pyrimidine dimers nor recovery of colony-forming ability. When C. parvum were exposed to fluorescent light after UV inactivation, UV-induced pyrimidine dimers in the DNA were continuously repaired, while no recovery of animal infectivity was observed. When kept in darkness after UV inactivation, C. parvum also showed no recovery of infectivity in spite of the repair of pyrimidine dimers. It was suggested, therefore, that the infectivity of C. parvum would not recover either by photoreactivation or by dark repair even after the repair of pyrimidine dimers in the genomic DNA