Does context really collapse in social media interaction?

'Context collapse' (CC) refers to the phenomenon widely debated in social media research, where various audiences convene around single communicative acts in new networked publics, causing confusion and anxiety among social media users. The notion of CC is a key one in the reimagination of social life as a consequence of the mediation technologies we associate with the Web 2.0. CC is undertheorized, and in this paper we intend not to rebuke it but to explore its limits. We do so by shifting the analytical focus from "online communication" in general to specific forms of social action performed, not by predefined "group" members, but by actors engaging in emerging kinds of sharedness based on existing norms of interaction. This approach is a radical choice for action rather than actor, reaching back to symbolic interactionism and beyond to Mead, Strauss and other interactionist sociologists, and inspired by contemporary linguistic ethnography and interactional sociolinguistics, notably the work of Rampton and the Goodwins. We apply this approach to an extraordinarily complex Facebook discussion among Polish people residing in The Netherlands - a set of data that could instantly be selected as a likely site for context collapse. We shall analyze fragments in detail, showing how, in spite of the complications intrinsic to such online, profoundly mediated and oddly 'placed' interaction events, participants appear capable of 'normal' modes of interaction and participant selection. In fact, the 'networked publics' rarely seem to occur in practice, and contexts do not collapse but expand continuously without causing major issues for contextualization. The analysis will offer a vocabulary and methodology for addressing the complexities of the largest new social space on earth: the space of online culture

Does context really collapse in social media interaction?

‘Context collapse’ (CC) refers to the phenomenon widely debated in social media research, where various audiences convene around single communicative acts in new networked publics, causing confusion and anxiety among social media users. The notion of CC is a key one in the reimagination of social life as a consequence of the mediation technologies we associate with the Web 2.0. CC is undertheorized, and in this paper we intend not to rebuke it but to explore its limits. We do so by shifting the analytical focus from “online communication” in general to specific forms of social action performed, not by predefined “group” members, but by actors engaging in emerging kinds of sharedness based on existing norms of interaction. This approach is a radical choice for action rather than actor, reaching back to symbolic interactionism and beyond to Mead, Strauss and other interactionist sociologists, and inspired by contemporary linguistic ethnography and interactional sociolinguistics, notably the work of Rampton and the Goodwins. We apply this approach to an extraordinarily complex Facebook discussion among Polish people residing in The Netherlands – a set of data that could instantly be selected as a likely site for context collapse. We shall analyze fragments in detail, showing how, in spite of the complications intrinsic to such online, profoundly mediated and oddly ‘placed’ interaction events, participants appear capable of ‘normal’ modes of interaction and participant selection. In fact, the ‘networked publics’ rarely seem to occur in practice, and contexts do not collapse but expand continuously without causing major issues for contextualization. The analysis will offer a vocabulary and methodology for addressing the complexities of the largest new social space on earth: the space of online culture

More oxygen during development enhanced flight performance but not thermal tolerance of Drosophila melanogaster

High temperatures can stress animals by raising the oxygen demand above the oxygen supply. Consequently, animals under hypoxia could be more sensitive to heating than those exposed to normoxia. Although support for this model has been limited to aquatic animals, oxygen supply might limit the heat tolerance of terrestrial animals during energetically demanding activities. We evaluated this model by studying the flight performance and heat tolerance of flies (Drosophila melanogaster) acclimated and tested at different concentrations of oxygen (12%, 21%, and 31%). We expected that flies raised at hypoxia would develop into adults that were more likely to fly under hypoxia than would flies raised at normoxia or hyperoxia. We also expected flies to benefit from greater oxygen supply during testing. These effects should have been most pronounced at high temperatures, which impair locomotor performance. Contrary to our expectations, we found little evidence that flies raised at hypoxia flew better when tested at hypoxia or tolerated extreme heat better than did flies raised at normoxia or hyperoxia. Instead, flies raised at higher oxygen levels performed better at all body temperatures and oxygen concentrations. Moreover, oxygen supply during testing had the greatest effect on flight performance at low temperature, rather than high temperature. Our results poorly support the hypothesis that oxygen supply limits performance at high temperatures, but do support the idea that hyperoxia during development improves performance of flies later in life

Photochemistry of 2-thiooxazole: a plausible prebiotic precursor to RNA nucleotides

Potentially prebiotic chemical reactions leading to RNA nucleotides involve periods of UV irradiation, which are necessary to promote selectivity and destroy biologially irrelevant side products. Nevertheless, UV light has only been applied to promote specific stages of prebiotic reactions and its effect on complete prebiotic reaction sequences has not been extensively studied. Here, we report on an experimental and computational investigation of the photostability of 2-thiooxazole (2-TO), a potential precursor of pyrimidine and 8-oxopurine nucleotides on early Earth. Our UV-irradiation experiments resulted in rapid decomposition of 2-TO into unidentified small molecule photoproducts. We further clarify the underlying photochemistry by means of accurate ab initio calculations and surface hopping molecular dynamics simulations. Overall, the computational results show efficient rupture of the aromatic ring upon the photoexcitation of 2-TO via breaking of the C-O bond. Consequently, the initial stage of the divergent prebiotic synthesis of pyrimidine and 8-oxopurine nucleotides would require periodic shielding from UV light either with sun screening chromophores or through a planetary scenario that would protect 2-TO until it is transformed into a more stable intermediate compound, e.g. oxazolidinone thione

HSP90 C-terminal Domain Binding Site For Novobiocin and Related Coumarins

Heat shock protein 90 (Hsp90) is a highly conserved, eukaryotic, molecular chaperone which stabilizes an assortment of oncogenic proteins. Currently, novobiocin and related coumarins are being developed into higher affinity analogs for the treatment of various cancers based on their inhibition of Hsp90 chaperone function. However, direct binding to Hsp90 has yet to be demonstrated; the existence of an Hsp90 binding site for these compounds has, to date, been based on a number of indirect assays. In order to address this gap in our knowledge, we used the technique of surface plasmon resonance (SPR) to assay the affinities of novobiocin derivatives for full length Hsp90 (Hsp90FL) and a C-terminal Hsp90 truncation (Hsp90CT). We also examined the effect of bound N-terminal ligands, ATP, ADP, and geldanamycin (GA), on the affinities for our compounds of interest. Results demonstrate that novobiocin and related coumarins bind to apo Hsp90FL and apo Hsp90CT with comparable affinities. Additionally, novobiocin and related compounds did not bind to the N terminal nucleotide binding pocket on Hsp90FL. Moreover, coumarin derivatives bound to Hsp90: ADP complexes with enhanced affinity. Our results demonstrate that a binding site for novobiocin related compounds resides on the C-terminus of Hsp90. Our results also support the hypothesis that the N-terminal and C-terminal domains of Hsp90 interact to moderate Hsp90 chaperone activity. Our results provide new insights into the mode of action by which novobiocin related compounds interact with Hsp90 in vitro and may suggest novel approaches to the development of higher affinity novobiocin derivatives in the treatment of cancer and related diseases.Department of Biochemistry and Molecular Biolog