Encounters on the social web: Everyday life and emotions online

Encounters also happen online nowadays and, yes, they are still difficult to describe, even though it is sometimes easier to observe them-and obtain data about them- than in the past. The internet is crucially 'shaping the interactions people have with one another' (Johns 2010: 499). With the recent explosion and popularity of Web 2.0 services and the social web, such as Facebook (FB), Twitter, and various other types of social media, internet users now have at their disposal an unprecedented collection of tools to interact with others. These modes of online sociability allow users to pursue social encounters with variable levels of involvement, attention, and activity (Papacharissi and Mendelson 2010). For many of us it is now difficult to imagine our social relationships without access to the internet. The social web plays an important role in relationships among internet users (Boyd 2006), with the expression, management and experience of emotions being key to the maintenance of these relationships

Ab-initio Phonon Calculations for the layered compound TiOCl

We present first-principles frozen-phonon calculations for the three Raman-active $A_g$ modes in the spin-1/2 layered TiOCl system within two different well-known approaches: the local density approximation (LDA) and the so-called LDA+U approximation. We observe that the inclusion of electron correlation in a mean-field level as implemented in the LDA+U leads to a better overall agreement with experimental results. We also discuss the implications of the two approaches on the physics of TiOCl.Comment: Phys. Rev. B (Rapid Comm.) (in Press

Magnon splitting induced by charge ordering in NaV_2O_5

We consider the effects of charge ordering in NaV_2O_5 (below T_SP) on the exchange constants and on the magnon dispersion. We show that the experimentally observed splitting of the magnon branches along the a direction is induced by charge ordering. We find that one can distinguish between the proposed 'zig-zag' and 'in-line' patterns of charge ordering. Only the zig-zag ordering is consistent with the experimental results regarding (i) the unusual intensity modulation observed in magnetic neutron scattering, (ii) the reduction in the intra-ladder exchange constant below T_SP, and (iii) the magnon dispersion along a. We estimate the inter-ladder exchange constant to be 1.01meV=11.7K for T>T_SP.Comment: final version for PR