1,615 research outputs found

    Local amplification of Rayleigh waves in the continental United States observed on the USArray

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    We develop a method based on ratios of amplitudes measured at adjacent stations to determine local amplification of surface waves across an array of seismic stations. We isolate the effects of local structure from those of the earthquake and propagation by systematic averaging of ratios corresponding to many sources. We apply the method to data recorded on the USArray for the years 2006–2011 and determine amplification factors at each station of the array for Rayleigh waves at periods between 35 s and 125 s. Local amplification factors are spatially coherent and display variations of ±10% at a period of 125 s and greater variations at shorter periods. Maps of local amplification exhibit spatial correlation with topography and geologic structures in the western and central United States. At long periods, the observed amplification factors correlate well with predictions from a regional crust and mantle model of North America. At short periods, correlations are weaker, suggesting that the local amplification factors can be useful for constraining shallow structure better

    Pelvic fin walking and punting behaviour of Raja radula Delaroche, 1809 observed in the Sea of Marmara

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    A mature female rough ray (Raja radula Delaroche, 1809) individual was observed at Sea of Marmara during a scuba dive to perform pelvic fin walking and punting, which was a previously unrecorded rajid behaviour from the Mediterranean Sea. The underwater video footage were analyzed, in which the average distance travelled per punt was measured as 0.40 disc length (DL) at an average speed of 0.26DL per second

    The Truth in Compatibilism and the truth of Libertarianism

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    The paper offers the outlines of a response to the often-made suggestion is that it is impossible to see how indeterminism could possibly provide us with anything that we might want in the way of freedom, anything that could really amount to control, as opposed merely to an openness in the flow of reality that would constitute merely the injection of chance, or randomness, into the unfolding of the processes which underlie our activity. It is suggested that the best first move for the libertarian is to make a number of important concessions to the compatibilist. It should be conceded, in particular, that certain sorts of alternative possibilities are neither truly available to real, worldly agents, nor required in order that those agents should act freely; and it should be admitted also that it is the compatibilist who tends to give the most plausible sorts of analyses of many of the ‘can’ and ‘could have’ statements which seem to need to be assertible of those agents we regard as free. But these concessions do not bring compatibilism itself in their wake. The most promising version of libertarianism, it is argued, should be based on the idea that agency itself (and not merely some special instances of it which we might designate with the honorific appellation ‘free’) is inconsistent with determinism. This version of libertarianism, it is claimed, can avoid the objection that indeterminism is as difficult to square with true agential control as determinism can sometimes seem to be
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