On how 'middle' plus 'associative/reciprocal' became 'passive' in the Bantu A70 languages

In this paper we show that the Bantu A70 languages did not preserve the passive morpheme inherited from Proto-Bantu (PB), but developed a new suffix. It is a morpheme that is compound in origin, consisting of two verbal derivation suffixes which still function independently in today's languages as a middle marker and an associative/reciprocal marker respectively, though with variable degrees of productivity. The genesis of a passive marker from the stacking of two pre-existing suffixes is a typologically rare evolution path, but it fits in with a wider Bantu phenomenon of double verb extensions which develop non-compositional meanings. Especially double extensions involving the Proto-Bantu associative/reciprocal marker *-an- tend to develop such idiosyncratic meanings. This suffix is also one of the constituents of the Bantu A70 passive marker Nevertheless, even within Bantu, the emergence of a productive passive marker from such double extension is unique. In this paper, we argue that the notion of co-participation may account for the rising of this passive meaning out of the stacking of the common Bantu associative/reciprocal suffix to a common Bantu middle suffix. The semantic development of this compound suffix fix (and its historical constituents) happened within the semantic continuum that links reciprocals, reflexives, middles and passives in many languages of the world, but did not necessarily follow the typologically common reflexive > reciprocal > middle > passive cline

Volatiles beneath mid-ocean ridges: deep melting, channelised transport, focusing, and metasomatism

Deep-Earth volatile cycles couple the mantle with near-surface reservoirs. Volatiles are emitted by volcanism and, in particular, from mid-ocean ridges, which are the most prolific source of basaltic volcanism. Estimates of volatile extraction from the asthenosphere beneath ridges typically rely on measurements of undegassed lavas combined with simple petrogenetic models of the mean degree of melting. Estimated volatile fluxes have large uncertainties; this is partly due to a poor understanding of how volatiles are transported by magma in the asthenosphere. Here, we assess the fate of mantle volatiles through numerical simulations of melting and melt transport at mid-ocean ridges. Our simulations are based on two-phase, magma/mantle dynamics theory coupled to idealised thermodynamic model of mantle melting in the presence of water and carbon dioxide. We combine simulation results with catalogued observations of all ridge segments to estimate a range of likely volatile output from the global mid-ocean ridge system. We thus predict global MOR crust production of 66-73 Gt/yr (22-24 km3/yr) and global volatile output of 52-110 Mt/yr, corresponding to mantle volatile contents of 100--200~ppm. We find that volatile extraction is limited: up to half of deep, volatile-rich melt is not focused to the axis but is rather deposited along the LAB. As these distal melts crystallise and fractionate, they metasomatise the base of the lithosphere, creating rheological heterogeneity that could contribute to the seismic signature of the LAB.Comment: 42 pages; 8 figures; 2 appendices (incl 1 table); 7 suppl. figures; 1 suppl. tabl

Motility at the origin of life: Its characterization and a model

Due to recent advances in synthetic biology and artificial life, the origin of life is currently a hot topic of research. We review the literature and argue that the two traditionally competing "replicator-first" and "metabolism-first" approaches are merging into one integrated theory of individuation and evolution. We contribute to the maturation of this more inclusive approach by highlighting some problematic assumptions that still lead to an impoverished conception of the phenomenon of life. In particular, we argue that the new consensus has so far failed to consider the relevance of intermediate timescales. We propose that an adequate theory of life must account for the fact that all living beings are situated in at least four distinct timescales, which are typically associated with metabolism, motility, development, and evolution. On this view, self-movement, adaptive behavior and morphological changes could have already been present at the origin of life. In order to illustrate this possibility we analyze a minimal model of life-like phenomena, namely of precarious, individuated, dissipative structures that can be found in simple reaction-diffusion systems. Based on our analysis we suggest that processes in intermediate timescales could have already been operative in prebiotic systems. They may have facilitated and constrained changes occurring in the faster- and slower-paced timescales of chemical self-individuation and evolution by natural selection, respectively.Comment: 29 pages, 5 figures, Artificial Lif

HYPE with stochastic events

The process algebra HYPE was recently proposed as a fine-grained modelling approach for capturing the behaviour of hybrid systems. In the original proposal, each flow or influence affecting a variable is modelled separately and the overall behaviour of the system then emerges as the composition of these flows. The discrete behaviour of the system is captured by instantaneous actions which might be urgent, taking effect as soon as some activation condition is satisfied, or non-urgent meaning that they can tolerate some (unknown) delay before happening. In this paper we refine the notion of non-urgent actions, to make such actions governed by a probability distribution. As a consequence of this we now give HYPE a semantics in terms of Transition-Driven Stochastic Hybrid Automata, which are a subset of a general class of stochastic processes termed Piecewise Deterministic Markov Processes.Comment: In Proceedings QAPL 2011, arXiv:1107.074