Environmental fragility in the Sahel

A companion to the OECD States of Fragility 2022 report, this paper analyses the drivers and effects of climate and environmental risks in the Sahel,focusing on increasing food insecurity, rapid urbanisation and intensified mining. It outlines options for improved policy responses by providers of development co-operation

Conformal proper times according to the Woodhouse causal axiomatics of relativistic spacetimes

On the basis of the Woodhouse causal axiomatics, we show that conformal proper times and an extra variable in addition to those of space and time, precisely and physically identified from experimental examples, together give a physical justification for the `chronometric hypothesis' of general relativity. Indeed, we show that, with a lack of these latter two ingredients, no clock paradox solution exists in which the clock and message functions are solely at the origin of the asymmetry. These proper times originate from a given conformal structure of the spacetime when ascribing different compatible projective structures to each Woodhouse particle, and then, each defines a specific Weylian sheaf structure. In addition, the proper time parameterizations, as two point functions, cannot be defined irrespective of the processes in the relative changes of physical characteristics. These processes are included via path-dependent conformal scale factors, which act like sockets for any kind of physical interaction and also represent the values of the variable associated with the extra dimension. As such, the differential aging differs far beyond the first and second clock effects in Weyl geometries, with the latter finally appearing to not be suitable.Comment: 25 pages, 2 figure

Does Quantum Mechanics Clash with the Equivalence Principle - and Does it Matter?

With an eye on developing a quantum theory of gravity, many physicists have recently searched for quantum challenges to the equivalence principle of general relativity. However, as historians and philosophers of science are well aware, the principle of equivalence is not so clear. When clarified, we think quantum tests of the equivalence principle won't yield much. The problem is that the clash/not-clash is either already evident or guaranteed not to exist. Nonetheless, this work does help teach us what it means for a theory to be geometric.Comment: 12 page

Choosing the realist framework

There has been an empiricist tradition in the core of Logical Positivism/Empiricism, starting with Moritz Schlick and ending in Herbert Feigl (via Hans Reichenbach), according to which the world of empiricism need not be a barren place devoid of all the explanatory entities posited by scientific theories. The aim of this paper is to articulate this tradition and to explore ways in which its key elements can find a place in the contemporary debate over scientific realism. It presents a way empiricism can go for scientific realism without metaphysical anxiety, by developing an indispensability argument for the adoption of the realist framework. This argument, unlike current realist arguments, has a pragmatic ring to it: there is no ultimate argument for the adoption of the realist framework. © 2009 Springer Science+Business Media B.V

Migration of myogenic cells in the rat extensor digitorum longus muscle studied with a split autograft model

The ability of myogenic cells to migrate perpendicular to the long axis of freely autografted muscles was examined. Rat extensor digitorum longus muscles were divided, and one half was devitalized by repeated freezing in liquid nitrogen while the other half was kept viable in physiologic saline. The halves were reunited with sutures and grafted back into the original muscle bed. At intervals between 5 and 25 days the grafts were removed and examined histologically for the presence of myotubes within the devitalized region. Myotubes were first seen in the devitalized half 10 days postgrafting with the maximum number of myotubes observed after 12 to 15 days. These results indicate that myogenic cells are capable of migration perpendicular to the long axis of the muscle fibers in an autograft.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47687/1/441_2004_Article_BF00327748.pd