Towards understanding mobile messaging ecologies : an exploration of the meanings young people attach to instant messaging channels

Mobile communications have added an ever present layer to our personal communication through which social dynamics can be reconstructed. In youth culture specifically, instant messaging allows young people to achieve limited autonomy, explore peer groups and an evolving sense of self. This dissertation explores a model for understanding how instant messaging facilitates this. Theories of media ecologies provide useful ways of explaining media environments. Nonetheless ecologies are usually conceptualised in relation to mass media rather than networked media and tend to assume that ecologies are situated in a particular physical space. The theory is nonetheless useful in understanding the everyday experience of young people using media. By extending media ecology theory to account for the personal communicative ecologies of instant messaging, this study extends the notion of ecology to account for a sense of digital social space outside the constructs of physical space. Through taking an interactional epistemological stance, qualitative research was conducted. Two focus groups were conducted to explore how instant messaging channels meet the needs of a group of young people from middle class contexts in Cape Town. The resultant discussions are applied to the framework of a 'layered' communicative ecology, taking technology, social and discursive layers into account and establishing the centrality of social space within a new and expanded model of networked messaging ecologies. The central aim of this research is to explore how relevant the application of media ecologies would be to an exploration of digital spaces of communication and practice

Einführung - Grammatikalisierung in interdisziplinärer Perspektive

Einführun

Benefits and New Features of a Modern International Internet Database “IOLCon” for Updated and Optimized IOL Constants and IOL Specifications

Cataract surgery has a history of about 2800 years. Harold Ridleyʼs invention of the intraocular lens in 1949 set a milestone in cataract surgery, supplying patients with a more or less satisfactory refractive implant for the first time. In the following 70 years, cataract surgery, IOL technology, and biometry have developed enormously. The invention of optical biometry in 1999 has again fundamentally changed cataract surgery. The introduction of the first optical biometer, the Zeiss IOLMaster, and Prof. Wolfgang Haigisʼ (University Würzburg, Germany) ULIB database of formula constants (http://ocusoft.de/ulib/) paved the way for this most successful new technology. In parallel, the number of IOL manufacturers, as well as IOL models and their technical capabilities (e.g., aspheric, multifocal, EDOF, and toric IOLs) have multiplied, making it more difficult for ophthalmic surgeons to maintain a clear overview of all the available options

Evolution in an Ancient Detoxification Pathway Is Coupled with a Transition to Herbivory in the Drosophilidae

Chemically defended plant tissues present formidable barriers to herbivores. Although mechanisms to resist plant defenses have been identified in ancient herbivorous lineages, adaptations to overcome plant defenses during transitions to herbivory remain relatively unexplored. The fly genus Scaptomyza is nested within the genus Drosophila and includes species that feed on the living tissue of mustard plants (Brassicaceae), yet this lineage is derived from microbe-feeding ancestors. We found that mustard-feeding Scaptomyza species and microbe-feeding Drosophila melanogaster detoxify mustard oils, the primary chemical defenses in the Brassicaceae, using the widely conserved mercapturic acid pathway. This detoxification strategy differs from other specialist herbivores of mustard plants, which possess derived mechanisms to obviate mustard oil formation. To investigate whether mustard feeding is coupled with evolution in the mercapturic acid pathway, we profiled functional and molecular evolutionary changes in the enzyme glutathione S-transferase D1 (GSTD1), which catalyzes the first step of the mercapturic acid pathway and is induced by mustard defense products in Scaptomyza. GSTD1 acquired elevated activity against mustard oils in one mustard-feeding Scaptomyza species in which GstD1 was duplicated. Structural analysis and mutagenesis revealed that substitutions at conserved residues within and near the substrate-binding cleft account for most of this increase in activity against mustard oils. Functional evolution of GSTD1 was coupled with signatures of episodic positive selection in GstD1 after the evolution of herbivory. Overall, we found that preexisting functions of generalized detoxification systems, and their refinement by natural selection, could play a central role in the evolution of herbivory