Martian impact basins: Morphology differences and tectonic provinces

Detailed geomorphic and structural mapping of five Martian basins and preliminary study of eleven other basins reveal four characteristic styles of modification that relate to the degree and age of past tectonic activity. Within regions that exhibit no evidence for tectonic activity, the modification style can be used to distinguish areas dominated by different exogenic processes. A framework for understanding these different styles of basin modification is provided

Nonaxisymmetric MHD instabilities of Chandrasekhar states in Taylor-Couette geometry

We consider axially periodic Taylor-Couette geometry with insulating boundary conditions. The imposed basic states are so-called Chandrasekhar states, where the azimuthal flow $U_\phi$ and magnetic field $B_\phi$ have the same radial profiles. Mainly three particular profiles are considered: the Rayleigh limit, quasi-Keplerian, and solid-body rotation. In each case we begin by computing linear instability curves and their dependence on the magnetic Prandtl number Pm. For the azimuthal wavenumber m=1 modes, the instability curves always scale with the Reynolds number and the Hartmann number. For sufficiently small Pm these modes therefore only become unstable for magnetic Mach numbers less than unity, and are thus not relevant for most astrophysical applications. However, modes with m>10 can behave very differently. For sufficiently flat profiles, they scale with the magnetic Reynolds number and the Lundquist number, thereby allowing instability also for the large magnetic Mach numbers of astrophysical objects. We further compute fully nonlinear, three-dimensional equilibration of these instabilities, and investigate how the energy is distributed among the azimuthal (m) and axial (k) wavenumbers. In comparison spectra become steeper for large m, reflecting the smoothing action of shear. On the other hand kinetic and magnetic energy spectra exhibit similar behavior: if several azimuthal modes are already linearly unstable they are relatively flat, but for the rigidly rotating case where m=1 is the only unstable mode they are so steep that neither Kolmogorov nor Iroshnikov-Kraichnan spectra fit the results. The total magnetic energy exceeds the kinetic energy only for large magnetic Reynolds numbers Rm>100.Comment: 12 pages, 14 figures, submitted to Ap

On the use of ATSR fire count data to estimate the seasonal and interannual variability of vegetation fire emissions

Biomass burning has long been recognised as an important source of trace gases and aerosols in the atmosphere. The burning of vegetation has a repeating seasonal pattern, but the intensity of burning and the exact localisation of fires vary considerably from year to year. Recent studies have demonstrated the high interannual variability of the emissions that are associated with biomass burning. In this paper I present a methodology using active fire counts from the Along-Track Scanning Radiometer (ATSR) sensor on board the ERS-2 satellite to estimate the seasonal and interannual variability of global biomass burning emissions in the time period 1996--2000. From the ATSR data, I compute relative scaling factors of burning intensity for each month, which are then applied to a standard inventory for carbon monoxide emissions from biomass burning. The new, time-resolved inventory is evaluated using the few existing multi-year burned area observations on continental scales

State education as high-yield investment: human capital theory in European policy discourse

Human Capital Theory has been an increasingly important phenomenon in economic thought over the last 50 years. The central role it affords to education has become even more marked in recent years as the concept of the ‘knowledge economy’ has become a global concern. In this paper, the prevalence of Human Capital Theory within European educational policy discourse is explored. The paper examines a selection of policy documents from a number of disparate European national contexts and considers the extent to which the ideas of Human Capital Theory can be seen to be influential. In the second part of the paper, the implications of Human Capital Theory for education are considered, with a particular focus on the possible ramifications at a time of economic austerity. The paper argues that Human Capital Theory risks offering a diminished view of the person, a diminished view of education, but that with its sole focus on economic goals leaves room for educationists and others to argue for the educational, social, and moral values it ignores, and for the conception of the good life and good society it fails to mention