Permeability changes in simulated granite faults during and after frictional sliding

Thermal–hydrological–mechanical coupling processes suggest that fault permeability should undergo dynamic change as a result of seismic slip. In igneous rocks, a fault's slip surface may have much higher permeability than the surrounding rock matrix and therefore operate as a conduit for fluids. We conducted laboratory experiments to investigate changes in fracture permeability (or transmissivity) of a fault in granite due to shear slip and cyclic heating and cooling. Our experiments showed that high initial fracture transmissivity (>10^?18 m³) was associated with a high friction coefficient and that transmissivity decreased during slip. We propose that this reduction in transmissivity reflects the presence of gouge in fracture voids, increasing the area of contact in the fault plane and reducing the hydraulic aperture. In contrast, when initial fracture transmissivity was low (<10^?18 m³), we observed that friction was lower and transmissivity increased during slip. The high transmissivity and high friction may be explained by large areas of bare rock being in contact on the slip surface. Slip velocity had little influence on the evolution of permeability, probably because gouge produced at different slip velocities had similar grain size distributions, or because gouge leaked from the slip surface. Transmissivity decreased with increasing temperature in heating tests, probably due to thermal expansion increasing normal stress on the fracture. Frictional heating did not influence transmissivity during the shearing tests.     

Behavioral Ecology and Archaeology

Behavioral ecology is the study of adaptive behavior in relation to social and environmental circumstances. Analysts working from this perspective hold that the reproductive strategies and decision-making capacities of all living organisms—including humans—are shaped by natural selection. Archaeologists have been using this proposition in the study of past human behavior for more than 30 years. Significant insights on variation in prehistoric human subsistence, life history, social organization, and their respective fossil and archaeological consequences have been among the more important results.     

State functioning and state failure in the South Pacific

The South Pacific region features enormous variation in state performance. While Polynesian nations such as Samoa have proved to be relatively successful post-colonial states, Melanesian countries like the Solomon Islands are increasingly categorised as 'weak', 'failing' or 'failed' states. Drawing on a range of comparative studies by economists and political scientists in recent years, this article argues that cross-country variation in ethnic diversity between much of Polynesia and Melanesia is a key factor in explaining differences in state performance across the South Pacific. It shows how different kinds of ethnic structure are associated with specific political and economic outcomes, including variation in political stability, economic development, and internal conflict from country to country. In so doing, it helps explain why some parts of the South Pacific appear to be failing while others are relative success stories - and why this is unlikely to change in the foreseeable future.     

Guy D’Arezzo et « Notre Notation Musicale Moderne »

In his Sociology of music, Max Weber stressed the importance of the invention of notation on lines by Guido of Arezzo (c. 990–1035). This article traces the beginnings of musical notation. Although Guido of Arezzo proposed a system of lines in which each note is always in the same place, he also placed the neumes invented before him on these lines. The first annotators sought to note with precision the rhythmic nuances and ornaments of the melodies; but those subtle indications disappeared little by little from the notation, betraying an inflexibility of the tradition, which contributed to the orientation of western music towards paths which did not know other music of oral tradition.