Learning from the experience of others: an experiment on information contagion

Advances in stochastic system analysis have opened the way to a reconsideration of the processes through which behaviors spread in a population of individuals or organizations. One peculiar phenomenon affecting diffusion is information contagion (Arthur and Lane 1994). When agents have to choose on the basis of other people’s experience, rather than relying on their own direct observations, information externalities arise that drive towards the emergence of the arbitrary, stable dominance of one product over the competing one. We reproduced in controlled laboratory conditions the process of information contagion. The experiments show that when agents can only resort to the observation of other people’s experience in choosing between competing alternatives, the choice process generates some peculiar features: - information contagion among subjects generates self-reinforcing dynamics, amplifying initial asymmetries of products’ market shares; - this in turn produces path-dependent trajectories, highly dependent on early events in the choice sequence; - arbitrary asymmetric market shares tend to be stable in the long run, exhibiting lock-in phenomena; - agents choice criteria are heterogenous, giving rise to a mix of positive and negative feedback in the choice process, with the mix and the timing of such criteria affecting the final outcome

Talking about routines in the field: the emergence of organizational capabilities in a new cellular phone network company

No abstract availabl

Modularity in action.GNU/Linux and free/Open source sotfware development model unleashed.

Organizational and managerial theories of modularity applied to the design and production of complex artifacts are used to interpret the rise and success of Free/Open Source Software methodologies and practices in software engineeringmodularity; software project management; free/open source software; division of labor; coordination; information hiding

Fragile three-dimensionality in the quasi-one-dimensional cuprate PrBa_2Cu_4O_8

In this article we report on the experimental realization of dimensional crossover phenomena in the chain compound PrBa$_2$Cu$_4$O$_8$ using temperature, high magnetic fields and disorder as independent tuning parameters. In purer crystals of PrBa$_2$Cu$_4$O$_8$, a highly anisotropic three-dimensional Fermi-liquid state develops at low temperatures. This metallic state is extremely susceptible to disorder however and localization rapidly sets in. We show, through quantitative comparison of the relevant energy scales, that this metal/insulator crossover occurs precisely when the scattering rate within the chain exceeds the interchain hopping rate(s), i.e. once carriers become confined to a single conducting element.Comment: 12 pages, 5 figures, published at http://www.iop.org/EJ/article/1367-2630/8/9/172/njp6_9_172.htm

Dimensionality-driven spin-flop transition in quasi-one-dimensional PrBa2Cu4O8

In the quasi-one-dimensional cuprate PrBa$_2$Cu$_4$O$_8$, the Pr cations order antiferromagnetically at 17 K in zero field. Through a combination of magnetic susceptibility, torque magnetometry, specific heat and interchain transport measurements, the anisotropic temperature-magnetic field phase diagram associated with this ordering has been mapped out. A low-temperature spin-flop transition in the Pr sub-lattice is found to occur at the same magnetic field strength and orientation as a dimensional crossover in the ground state of the metallic CuO chains. This coincidence suggests that the spin reorientation is driven by a change in the anisotropic Rudermann-Kittel-Kasuya-Yosida (RKKY) interaction induced by a corresponding change in effective dimensionality of the conduction electrons.Comment: 8 pages, 8 figure

Violation of the isotropic-ℓ\ell approximation in overdoped La_{2-x}Sr_xCuO_4

Magnetotransport measurements on the overdoped cuprate La_{1.7}Sr_{0.3}CuO_4 are fitted using the Ong construction and band parameters inferred from angle-resolved photoemission. Within a band picture, the low temperature Hall data can only be fitted satisfactorily by invoking strong basal-plane anisotropy in the mean-free-path $\ell$. This violation of the isotropic-$\ell$ approximation supports a picture of dominant small-angle elastic scattering in cuprates due to out-of-plane substitutional disorder. We show that both band anisotropy and anisotropy in the elastic scattering channel strongly renormalize the Hall coefficient in overdoped La_{2-x}Sr_xCuO_4 over a wide doping and temperature range.Comment: 4 pages, 4 figure

Less is more in physics:A small-scale Writing in the Disciplines (WiD) intervention

This article reports on a Writing in the Disciplines (WiD) intervention for first year undergraduate physics (and joint Honours) students. A short (200-250 word) assignment was designed to maximise studentsââ¬â¢ learning of specific scientific writing practices, including writing with appropriate clarity and academic style for a target audience, incorporating mathematical expressions in text, creating diagrams and referring to them in text, and appropriately using citing and referencing. Peer marking was employed to offer students formative feedback before they completed the assignment. The success of the assignment as a vehicle for student learning was evaluated by reviewing the studentsââ¬â¢ submissions and marks awarded, and through ten studentsââ¬â¢ reported focus group responses to the experience of carrying out the assignment, their reaction to peer marking, and their responses to the assessorââ¬â¢s written and verbal feedback. The effectiveness of the assignmentââ¬â¢s content and process, and the peer marking, are briefly discussed, and suggestions made as to how to improve this or similar assignments in future years