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Malagasy Dialects and the Peopling of Madagascar
No full textServa M, Petroni F, Volchenkov D, Wichmann S. Malagasy Dialects and the Peopling of Madagascar. Interface. Journal of the Royal Society. 2012;9(66):54-67
Constant speed random particles spontaneously confined on the surface of an expanding sphere
Full text linkThe particles that we describe here can only move at the speed of light c in three-dimensional space. The velocity, which randomly but continuously changes direction, can be represented as a point on the surface of a sphere of constant radius c, and its trajectories may only connect points of this variety. The Wiener process that we use to describe the velocity dynamics on the surface of the sphere is anisotropic since the infinitesimal variation of the velocity is not only always orthogonal to the velocity itself (which guarantees a constant speed), but also to the position. This choice for the infinitesimal variation of the velocity is the one that best slows down the diffusion of particles in space by random motion at the speed of light. As a result of these dynamics, the position of the particles spontaneously remain confined on the surface of an expanding sphere whose radius increases, for large times, as the square root of time
Brownian Motion at the Speed of Light: A New Lorentz Invariant Family of Processes
Full text linkWe consider here a new family of processes which describe particles which only can move at the speed of light c in the ordinary 3D physical space. The velocity, which randomly changes direction, can be represented as a point on the surface of a sphere of radius c and its trajectories only may connect points of this variety. A process can be constructed both by considering jumps from one point to another (velocity changes discontinuously) and by continuous velocity trajectories on the surface. We recently proposed to follow this second strategy assuming that the velocity is described by a Wiener process (which is isotropic only in the ’rest frame’) on the surface of the sphere. Using both Ito calculus and Lorentz boost rules, we succeed here in characterizing the entire Lorentz-invariant family of processes. Moreover, we highlight and describe the short-term ballistic behavior versus the long-term diffusive behavior of the particles in the 3D physical space
Particles with constant speed and random velocity in 3+1 space-time: separation of the space variables
Full text linkWe consider a particle in 3+1 space-time dimensions which constantly moves at speed of light c, randomly changing its velocity which can be represented by a point on the surface of a sphere of radius c. The velocity performs an isotropic Wiener process on this surface so that the velocity trajectories are almost everywhere continuous although not differentiable, while the position trajectories are continuous and differentiable. Together with the process that describes the particle in the 'rest frame', where the diffusion of velocity on the surface of the sphere is isotropic, the entire family of anisotropic processes which result from Lorentz boosts is also described. The focus of this article is on stochastic evolution in space. We identify a reduced set of variables whose stochastic evolution is autonomous from the remaining variables, but, nevertheless, carry all the relevant information concerning the spatial properties of the process. The associated stochastic equations as well the Forward Kolmogorov equation are considerably simplified compared to those of the complete set of position and velocity variables
Dialects of Madagascar
Full text linkAll results in this paper are based upon a new dataset consisting in 60 Swadesh lists of 207 items, overall 12,420 terms collected during 2018-2019. Each list corresponds to a different variety of Malagasy, which is not simply identified by the name of the ethnicity but also by the precise location where the variety was collected. This is very important since some traditional ethnic groups are a heritage of historical events rather than representing communities with similar habits and dialects. This new dataset is by far the best available, both for dimension and completeness. The varieties are classified both by standard tools, as the trees generated by UPGMA and NJ which privilege genealogy by detecting vertical transmissions, and by a new method which privileges horizontal exchanges. The new method results in a two-dimensional chart of Madagascar which realistically reproduces geography despite being generated only by comparison of words. The landing date of the ancestors of Malagasy is determined about 650 CE. This result is obtained by a straightforward approach based on the comparison of the UPGMA Malagasy family tree with the analogous tree of Romance family of languages for which all dates are well historically attested. We also propose an improved definition of Diversity computed for every locus in Madagascar and not only in places where the dialects were collected. Moreover, Diversity becomes a locally determined quantity as it is usually in biology. Diversity differences point to the South-East coast as the location where the first colonizers landed or, at least, where Malagasy variants started their dispersion. Finally, we find that the dialect spoken by the Mikea, a hunter-gatherer people in the South-West of Madagascar, is not very different from the variants of their neighbours Vezo and Masikoro. Therefore, Mikea unlikely can be linked to eventual aboriginal populations living in Madagascar prior to the main colonization event in 650 CE. Copyright
Malagasy dialects in Mayotte
No full textThe Malagasy language is not strictly confined to Madagascar but it is also spoken in Mayotte, one of the four islands which constitute the Comoros archipelago. The inhabitants of Mayotte are, in fact, divided between two very distinct mother languages, one is Shimaore, a Bantu dialect similar to the dialects spoken in the other three islands, the other is Malagasy, an Austronesian language. In turn, Malagasy is represented by two distinct varieties, one is the Kibosy Kimaore, a name which simply means "Malagasy of Mayotte"(this name is sometimes used to indistinctly denote both varieties) and the other is the Kibosy Kiantalaotsy. It is usually stated that Kibosy Kimaore is close to the Northern Madagascar varieties, while Kibosy Kiantalaotsy is very close to Mahajanga Sakalava (Glottolog classifies Mahajanga Sakalava and Kibosy Kiantalaotsy as twin varieties). While we clearly confirm the cladistic position of Kibosy Kimaore, we find that Kibosy Kiantalaotsy is not particularly close to Mahajanga Sakalava, but it is closer to the Sakalava dialects of the South-West of Madagascar. Moreover, Kibosy Kiantalaotsy seems to be rather the result of multiple contributions from Madagascar than the offspring of a single dialect or a few dialects. Our outcome is based upon the comparison of the two Mayotte varieties with sixty different Madagascar varieties
Stability of Meanings versus Rate of Replacement of Words: An Experimental Test
No full textThe words of a language are randomly replaced over time by new ones, but it has long been known that words corresponding to some items (meanings) are less frequently replaced than others. Usually, the rate of replacement for a given item is not directly observable, but it is inferred by the estimated stability which, on the contrary, is observable. This strategy goes back a long way in the lexicostatistical literature, nevertheless nothing ensures that it gives the correct answer. The family of Romance languages allows for a direct test of the estimated stabilities against the replacement rates since the proto-language (Late Classical Latin or Vulgar Latin) is more or less known, and the replacement rates can be explicitly computed. The output of the test is threefold: i) we prove that the standard approach which infers the replacement rates through the estimated stabilities is sound; ii) we are able to rewrite the fundamental formula of Glottochronology for a non universal replacement rate (depending on the item); iii) we provide unquestionable evidence that the stability ranking is far from being the same for different families of languages. This last result is also supported by comparison with the Malagasy family of dialects
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