On the Hausdorff dimension of CAT(κ\kappa) surfaces

We prove that a closed surface with a CAT($\kappa$) metric has Hausdorff dimension = 2, and that there are uniform upper and lower bounds on the two-dimensional Hausdorff measure of small metric balls. We also discuss a connection between this uniformity condition and some results on the dynamics of the geodesic flow for such surfaces. Finally, we give a short proof of topological entropy rigidity for geodesic flow on certain CAT(-1) manifolds.Comment: 13 pages, 3 figure

The existence of a critical length scale in regularised friction

We study a regularisation of Coulomb's friction law on the propagation of local slip at an interface between a deformable and a rigid solid. This regularisation, which was proposed based on experimental observations, smooths the effect of a sudden jump in the contact pressure over a characteristic length scale. We apply it in numerical simulations in order to analyse its influence on the behaviour of local slip. We first show that mesh convergence in dynamic simulations is achieved without any numerical damping in the bulk and draw a convergence map with respect to the characteristic length of the friction regularisation. By varying this length scale on the example of a given slip event, we observe that there is a critical length below which the friction regularisation does not affect anymore the propagation of the interface rupture. A spectral analysis of the regularisation on a periodic variation of Coulomb's friction is conducted to confirm the existence of this critical length. The results indicate that if the characteristic length of the friction regularisation is smaller than the critical length, a slip event behaves as if it was governed by Coulomb's law. We therefore propose that there is a domain of influence of the friction regularisation depending on its characteristic length and on the frequency content of the local slip event. A byproduct of the analysis is related to the existence of a physical length scale characterising a given frictional interface. We establish that the experimental determination of this interface property may be achieved by experimentally monitoring slip pulses whose frequency content is rich enough.Comment: 21 pages, 7 figure

A New Species of \u3ci\u3eNanodacna\u3c/i\u3e Clarke (Lepidoptera: Elachistldae: Agonoxeninae) Feeding on the Seeds of \u3ci\u3eAustrocedrus chilensis\u3c/i\u3e (Cupressaceae) in Andean Argentina

Charaders of the adult, larva, and pupa of Nanodacna allstrocedrella Landry & Adamski, new species, are described and illustrated. The seed-feeding larvae cause damage to Andean Cedar, cipres de la cordillera [Austrocedrus chilcnsis (D. Don.) Fl. & Bout., Cupressaceae] in Chubut Province, Argentina. The species is compared to other species of Nanodacna and to species of Hornoeoprepes Walsingham from the Neotropics. Criteria for its inclusion in Nanodacna and the phylogenetic Significance of characters of immature stages for relationships within the Agonoxeninae are discussed

Exploiting Non-Linearities in GDP Growth for Forecasting and Anticipating Regime Changes

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Development, A question of Opportunity. A critique of the 2006 World Development Report, Equity and Development

The World Bank’s World Development Report 2006 addresses Equity and Development. It defines equity as respect for equal opportunities combined with the avoidance of absolute deprivation. Even though justice theories have long been interested in equity (given that equality of opportunity is one of the recognised values of Western society), it has hitherto remained a marginal issue in development economics. Our critique presents a detailed analysis of this report in the light of recent economic studies on this subject and endeavours to place it in the context of the evolution of World Bank thinking and policies. The first part illustrates the wealth of this concept, with its downside being that it is hard to accurately define. The second part demonstrates the gap between the prospects opened up by the enlargement of the development goals beyond poverty reduction and the report’s policy recommendations, which are generally an extension of the World Bank’s traditional analyses. The future of the equity concept for development policy-making could be closely dependent on the development community’s ability to take on board both all its complexity and wealth.

The Seasonal Cycle and Interannual Variability in Stratospheric Temperatures and Links to the Brewer–Dobson Circulation: An Analysis of MSU and SSU Data

Previous studies have shown that lower-stratosphere temperatures display a near-perfect cancellation between tropical and extratropical latitudes on both annual and interannual time scales. The out-of-phase relationship between tropical and high-latitude lower-stratospheric temperatures is a consequence of variability in the strength of the Brewer–Dobson circulation (BDC). In this study, the signal of the BDC in stratospheric temperature variability is examined throughout the depth of the stratosphere using data from the Stratospheric Sounding Unit (SSU). While the BDC has a seemingly modest signal in the annual cycle in zonal-mean temperatures in the mid- and upper stratosphere, it has a pronounced signal in the month-to-month and interannual variability. Tropical and extratropical temperatures are significantly negatively correlated in all SSU channels on interannual time scales, suggesting that variations in wave driving are a major factor controlling global-scale temperature variability not only in the lower stratosphere (as shown in previous studies), but also in the mid- and upper stratosphere. The out-of-phase relationship between tropical and high latitudes peaks at all levels during the cold-season months: December–March in the Northern Hemisphere and July–October in the Southern Hemisphere. In the upper stratosphere, the out-of-phase relationship with high-latitude temperatures extends beyond the tropics and well into the extratropics of the opposite hemisphere. The seasonal cycle in stratospheric temperatures follows the annual march of insolation at all levels and latitudes except in the mid- to upper tropical stratosphere, where it is dominated by the semiannual oscillation. M