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Scholars, advertisers and political activists see massive online social networks as a representation of social interactions that can be used to study the propagation of ideas, social bond dynamics and viral marketing , among others. But the linked structures of social networks do not reveal actual interactions among people. Scarcity of attention and the(More)
The subject of collective attention is central to an information age where millions of people are inundated with daily messages. It is thus of interest to understand how attention to novel items propagates and eventually fades among large populations. We have analyzed the dynamics of collective attention among 1 million users of an interactive web site,(More)
The tragedy of the digital commons does not prevent the copious voluntary production of content that one witnesses in the web. We show through an analysis of a massive data set from YouTube that the productivity exhibited in crowdsourcing exhibits a strong positive dependence on attention, measured by the number of downloads. Conversely, a lack of attention(More)
The CLC-family protein CLC-ec1, a bacterial homologue of known structure, stoichiometrically exchanges two Cl(-) for one H(+) via an unknown membrane transport mechanism. This study examines mutations at a conserved tyrosine residue, Y445, that directly coordinates a Cl(-) ion located near the center of the membrane. Mutations at this position lead to(More)
  • Yiling Fang, Hariharan Jayaram, Tania Shane, Ludmila Kolmakova-Partensky, Fang Wu, Carole Williams +2 others
  • 2009
To reach the mammalian gut, enteric bacteria must pass through the stomach. Many such organisms survive exposure to the harsh gastric environment (pH 1.5-4) by mounting extreme acid-resistance responses, one of which, the arginine-dependent system of Escherichia coli, has been studied at levels of cellular physiology, molecular genetics and protein(More)
Protein synthesis at distal synaptic sites is thought to play a critical role in long-term synaptic plasticity at preexisting connections. We tested whether protein synthesis in distal neuritic processes contributes to the formation of new synaptic connections by Aplysia neurons regenerating in cell culture after removing their cell bodies. Removal of(More)
The release of the serine proteinase tissue-type plasminogen activator (tPA) from cerebral cortical neurons has a neuroprotective effect in the ischemic brain. Because excitotoxicity is a basic mechanism of ischemia-induced cell death, here we investigated the effect of tPA on excitotoxin-induced neuronal death. We report that genetic overexpression of(More)