The (In)Difference engine: explaining the disappearance of diversity in the design of the personal computer

At the time of writing there is a clear perception of all office computers as being more or less identical. Discussion with users entails repetitive rhetoric as they describe a landscape of boring beige boxes. The office PC is indeed a ‘clone’ - an identical, characterless copy of a bland original. Through the exploration of an archive of computer manufacturer’s catalogues, this article shows how previous, innovative forms of the computer informed by cultural references as diverse as science fiction, accepted gender roles and the discourse of status as displayed through objects, have been systematically replaced by the adoption of a ‘universal’ design informed only by the nondescript, self-referential world of office equipment. The acceptance of this lack of innovation in the design of such a truly global, mass-produced, multi-purpose technological artefact has had an enormous effect on the conception, perception and consumption of the computer, and possibly of information technology itself. The very anonymity of the PC has created an attitude of indifference at odds with its potential.</p

The brittleness index in hydraulic fracturing

We present a new definition of a brittleness index which is used as a criterion for candidate selection of rock intervals for hydraulic fracturing. The new index is a combination of material strength parameters and insitu stresses. It was derived from an analytical model of hydraulic fracturing in weak formations of varying ductility. The model is based on Mohr-Coulomb dislocations that are placed in the effective centres of the complete slip process that is distributed around the crack tip. The new brittleness index varies between 0 and 1 with the one limit to correspond to brittle propagation and the other limit to a fracture that requires infinite energy release per unit advance. The values between 0 and 1 correspond to fracture propagation of increasing ductility from brittle to small scale and finally to large scale yielding. The results are particularly interesting for predicting the propagation of axial fractures in the horizontal direction and their confinement in the vertical direction

Interband effects in the c-axis optical conductivity in YBaCuO

The normal state optical conductivity is calculated for a layered metal with two layers per unit cell coupled through a transverse hopping matrix element $t_\perp$. The optical response involves an interband term in addition to the more familiar intraband term which leads to the usual Drude form. The interband term is only weakly temperature dependent, even for an inelastic scattering rate which is linear in T. It gives a $c$-axis response which extends in frequency over the entire band width although there can be structure on this energy scale which reflects details of the electronic structure. In particular, at low energy, the $c$-axis response can develop a gap or pseudogap as the temperature is lowered. At high temperature, a Drude response will be seen only if the intraband transitions, which are of order $t_\perp^4$, become important compared with the interband transitions which are of order $t_\perp^2$.Comment: 12 Pages, 9 postscript figures, submitted to Phys. Rev.

Contributions to workload of rotational optical transformations

An investigation of visuomotor adaptation to optical rotation and optical inversion was conducted. Experiment 1 examined the visuomotor adaptability of subjects to an optically rotating visual world with a univariate repeated measures design. Experiment 1A tested one major prediction of a model of adaptation put forth by Welch who predicted that the aversive drive state that triggers adaptation would be habituated to fairly rapidly. Experiment 2 was conducted to investigate the role of motor activity in adaptation to optical rotation. Specifically, this experiment contrasted the reafference hypothesis and the proprioceptive change hypothesis. Experiment 3 examined the role of cognition, error-corrective feedback, and proprioceptive and/or reafferent feedback in visuomotor adaptation to optical inversion. Implications for research and implications for practice were suggested for all experiments

Quantum interference in nested d-wave superconductors: a real-space perspective

We study the local density of states around potential scatterers in d-wave superconductors, and show that quantum interference between impurity states is not negligible for experimentally relevant impurity concentrations. The two impurity model is used as a paradigm to understand these effects analytically and in interpreting numerical solutions of the Bogoliubov-de Gennes equations on fully disordered systems. We focus primarily on the globally particle-hole symmetric model which has been the subject of considerable controversy, and give evidence that a zero-energy delta function exists in the DOS. The anomalous spectral weight at zero energy is seen to arise from resonant impurity states belonging to a particular sublattice, exactly as in the 2-impurity version of this model. We discuss the implications of these findings for realistic models of the cuprates.Comment: 12 pages, 10 figs, submitted to Phys. Rev.

Argumentation schemes for collaborative planning

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Influence of national culture and balanced organizational culture on the hotel industry's performance

This study investigates the role of national culture and balanced organisational culture in organisational performance. Hotel management requires flexibility and customer responsiveness to deal with increasingly demanding customers and competitiveness of the market. Studies of the influence of culture on performance in hotel management have not yet revealed the specific impact of national culture and balanced organisational culture on organisational performance. We use the concept of balanced organisational culture which posits that polyrational organisations are more responsive to market changes and more innovative. Data were gathered from 96 hotels in London, UK, and were analysed using structural equation modelling. Our findings show that the national culture of hotel employees influences balanced organisational culture which, in turn, influences performance. This study contributes to existing understanding of factors affecting performance, points towards further research, helps practitioners by demonstrating the importance of taking national culture into account and indicates the importance of achieving balanced organisational culture