Bibliography of Pragmatics Online: 12th Release, updated and expanded

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Drift Laws for Spiral Waves on Curved Anisotropic Surfaces

Rotating spiral waves organize spatial patterns in chemical, physical and biological excitable systems. Factors affecting their dynamics such as spatiotemporal drift are of great interest for par- ticular applications. Here, we propose a quantitative description for spiral wave dynamics on curved surfaces which shows that for a wide class of systems, including the BZ reaction and anisotropic cardiac tissue, the Ricci curvature scalar of the surface is the main determinant of spiral wave drift. The theory provides explicit equations for spiral wave drift direction, drift velocity and the period of rotation. Depending on the parameters, the drift can be directed to the regions of either maximal or minimal Ricci scalar curvature, which was verified by direct numerical simulations.Comment: preprint before submission to Physical Review

Performatives and (im)perfective aspect

Michael Meeuwis, Astrid De Wit & Frank Brisard Performatives and (im)perfective aspect (lecture) This paper represents the first (methodological) step in a cross-linguistic study on the relation between performativity and aspect. It starts from the observation that verbs, when used as performatives, are typically inflected with (present) perfective aspect. This can be motivated on the basis of the indexical quality of performatively used verbs: the activity referred to by performatives (such as I promise to come) can be said to coincide exactly with the act of referring to it. Thus, we may say that the denoted situation (the speech act of promising) is in fact constituted by the speech event (Langacker 2001). As a result, the situation at issue is fully conceptualized at the time of speaking by definition, which would typically trigger perfective aspectual marking: perfective expressions designate situations that are treated as known and closed. Imperfective aspect, in contrast, is associated with construing situations as incomplete and open. For instance, using progressive marking (a kind of imperfective aspect) in an utterance like I’m promising to come has the effect of turning it into a mere description of an ongoing event, thereby canceling its performative character. It is possible, however, that this assumption of a correlation between performativity and perfectivity is biased by a privileging of examples from English, in which performative contexts obligatorily feature the simple present (and the simple present is commonly assumed to have a perfective value; cf. Brinton (1988), Smith (1997: 110-112, 185-186), Williams (2002: 128-166) and De Wit et al. (2013)). However, data from Slavic -- the only language family for which the relation between performativity and aspect has been examined thoroughly (cf. Israeli 2001; Dickey forthcoming) -- indicate an opposite tendency: most Slavic languages, especially from the eastern branch (such as Russian), almost exclusively allow imperfective verbs in performative contexts. Jaggar (2006) furthermore indicates that performative expressions in Hausa trigger both perfective and imperfective marking. The correlation therefore needs to be checked cross-linguistically, an endeavor that requires a suitable questionnaire offering contexts that are universally accepted as triggering performative uses. Our purpose is to present such a questionnaire and to discuss its methodological potential and limitations. A crucial element will be to elicit and identify performatives without having to resort to aspectual tests, such as in English (present simple vs progressive). By wayof a pilot study, we will also offer our first findings based on native speaker elicitations in Lingala, Turkish and Sranan

Performativity, progressive avoidance and aspect

Unlike other reports of ongoing actions, English explicit performatives do not normally take progressive form. This suggests that “there is something over and above a mere concurrent report” in utterances like I bet you I’ll win the race that is absent in utterances like I’m betting you I’ll win the race (Levinson 1983: 259). For Krifka (2014), an explicit performative describes not the utterance act being produced, but the adoption of a new commitment, which has already happened at encoding time. If this is so, however, we might expect to find preterit- or present-perfect-form performative clauses and it appears that we do not. Using cross-linguistic data from genetically and geographically unrelated languages, we establish a strong typological tendency: explicit performative utterances use the same verbal construction that is used for reporting states holding at coding time. We attribute this tendency to an epistemic commonality between explicit performatives and state reports. In addition, we offer an explanation for exceptional uses of progressive aspect in apparently performative expressions, noted by, e.g., Searle (1989). Building on Dahl (1985), we have developed a questionnaire that allows us to identify the aspectual distinctions made in individual languages and which of these categories are employed in the various performative contexts (as classified by Searle 1976). Imperfective aspect is used to encode performatives and present-time states in, e.g., Arabic, Turkish and Bosnian/Croatian/Serbian. In Bantu languages like Lingala and Kirundi, performative predications receive perfective encoding, and this same form is used to report states holding at present. Japanese and the Austronesian language Kilivila feature unmarked verb forms in both present state reports and performative expressions. Progressive aspect is systematically excluded in the languages of our sample. Thus, in light of these typological observations, the use of the English simple present in performative contexts is not unexpected. The fact that present-time states and performative events receive the same aspectual construal across languages suggests a semantic commonality that cannot be conceived in terms of boundedness, one of the major parameters used to describe aspectual distinctions. We argue instead that aspectual categories encode epistemic distinctions, and that states and performative events are similar at this epistemic level: the situation type expressed by a performative or state predication is verifiable at the time of speaking. States have the subinterval property, according to which every segment of a state counts as an instance of that state, including that segment that overlaps the speech event. In the case of performatives, the reporting event and the performed event (promising, etc.) are one and the same; therefore, performative events are verifiable as such at speech time. The few scholars who touch on performativity and aspect in English appear to assume that in the rare attestations of progressive perfomatives, the predication does not perform a speech act (like promising) but rather reports on one’s own performance, as in I’m not just saying, I’m promising (Langacker 1987; Verschueren 1995; Krifka 2014). However, this characterization is not evidently applicable to examples like I’m warning you, Mrs. Hinkle: one more obscenity and I’ll charge you with contempt, which does count as a warning. Analysis of COCA data reveals that one type of performative clause, the exercitive type (Austin 1962), involving verbs such as warn and order, accounts for the majority of progressive performative tokens. Following McGowan (2004), we assume that exercitive acts change the boundaries of permissible or appropriate conduct. We postulate that progressive-form exercitive acts do not change these boundaries but rather describe an effort to do so. More generally, progressive performatives are action glosses like I’m trying to repair this; they explain the purpose of ongoing actions, both linguistic and nonlinguistic. This account naturally extends to non-exercitive progressive performatives like I’m withdrawing as a candidate

Alien Registration- Brisard, Edmund J. (South Berwick, York County)

https://digitalmaine.com/alien_docs/6029/thumbnail.jp

Combining Galerkin approximation techniques with the principle of Hashin and Shtrikman to derive a new FFT-based numerical method for the homogenization of composites

International audienceWe report on the mathematical analysis of two different, FFT-based, numerical schemes for the homogenization of composite media within the framework of linear elasticity: the basic scheme of Moulinec and Suquet (1994, 1998) [9] and [10], and the energy-based scheme of Brisard and Dormieux (2010) [13]. Casting these two schemes as Galerkin approximations of the same variational problem allows us to assert their well-posedness and convergence. More importantly, we extend in this work their domains of application, by relieving some stringent conditions on the reference material which were previously thought necessary. The origins of the flaws of each scheme are identified, and a third scheme is proposed, which seems to combine the strengths of the basic and energy-based schemes, while leaving out their weaknesses. Finally, a rule is proposed for handling heterogeneous pixels/voxels, a situation frequently met when images of real materials are used as input to these schemes

Periodic homogenization using the Lippmann--Schwinger formalism

When homogenizing elliptic partial differential equations, the so-called corrector problem is pivotal to compute the macroscale effective coefficients from the microscale information. To solve this corrector problem in the periodic setting, Moulinec and Suquet introduced in the mid-nineties a numerical strategy based on the reformulation of that problem as an integral equation (known as the Lippmann--Schwinger equation), which is then suitably discretized. This results in an iterative, matrix-free method, which is of particular interest for complex microstructures. Since the seminal work of Moulinec and Suquet, several variants of their scheme have been proposed. The aim of this contribution is twofold. First, we provide an overview of these methods, recast in the language of the applied mathematics community. These methods are presented as asymptotically consistent Galerkin discretizations of the Lippmann--Schwinger equation. The bilinear form arising in the weak form of this integral equation is indeed the sum of a local and a non-local term. We show that most of the variants proposed in the literature correspond to alternative approximations of this non-local term. Second, we propose a mathematical analysis of the discretized problem. In particular, we prove under mild hypotheses the convergence of these numerical schemes with respect to the grid-size. We also provide a priori error estimates on the solution. The article closes on a three-dimensional numerical application within the framework of linear elasticity

FFT-based methods for the mechanics of composites: A general variational framework

International audienceFor more than a decade, numerical methods for periodic elasticity, based on the fast Fourier transform, have been used successfully as alternatives to more conventional (fem, bem) numerical techniques for composites. These methods are based on the direct, point-wise, discretization of the Lippmann-Schwinger equation, and a subsequent truncation of underlying Fourier series required for the use of the fast Fourier transform. The basic FFT scheme is very attractive, because of its simplicity of implementation and use. However, it cannot handle pores or rigid inclusions, for which a specific (and significantly more involved) treatment is required. In the present paper, we propose a new FFT-based scheme which is as simple as the basic scheme, while remaining valid for infinite contrasts. Since we adopted an energy principle as an alternative to the Lippmann-Schwinger equation, our scheme is derived within a variational framework. As a by-product, it provides an energetically consistent rule for the homogenization of boundary voxels, a question which has been pending since the introduction of Fourier-based methods