MAGMA: a 3D, Lagrangian magnetohydrodynamics code for merger applications

We present a new, completely Lagrangian magnetohydrodynamics code that is based on the SPH method. The equations of self-gravitating hydrodynamics are derived self-consistently from a Lagrangian and account for variable smoothing length (``grad-h''-) terms in both the hydrodynamic and the gravitational acceleration equations. The evolution of the magnetic field is formulated in terms of so-called Euler potentials which are advected with the fluid and thus guarantee the MHD flux-freezing condition. This formulation is equivalent to a vector potential approach and therefore fulfills the $\vec{\nabla}\cdot\vec{B}=0$-constraint by construction. Extensive tests in one, two and three dimensions are presented. The tests demonstrate the excellent conservation properties of the code and show the clear superiority of the Euler potentials over earlier magnetic SPH formulations.Comment: 18 pages, 17 Figures, a high resolution copy of the paper can be found at http://www.faculty.iu-bremen.de/srosswog/MAGMA.pd

Modelling Aspects of Reduction and Assimilation of consonant sequences in Spontaneous French Speech

International audienceThe following paper presents spectrographic data of consonant sequences containing one or two consonants omitted and/or changed into another consonant when compared to an existing perception analysis. In most cases, perceptual and acoustic data are shown to strongly correspond, proving that consonants had indeed been changed, significantly reduced or deleted, mainly in a weak position, thereby preserving acoustic information crucial for lexical access, integration of prosodic structure and successful communication. Tentative rules summarise the tendencies observed in reduction and assimilation patterns

Consonant and Vowel Duration in Parkinsonian French Speech

International audienceThe current study compared vowel and consonant duration in speech read by 10 French Parkinsonian speakers and 10 control speakers. The results show a different impact of Parkinson's disease (PD) on speech segments. Consonants were shortened in PD speech while vowels were significantly longer. This results from the concomitance of articulatory movements of reduced amplitude and orofacil bradykinesia. As a consequence syllabic productions are of the overall duration in PD speech as in normal speech. The durational contrast of consonants was maintained, although for vowels there was less agreement with the normal pattern of intrinsic durations, especially for high vowels

Acoustic Properties of Consonant Sequences in Conversational French Speech

International audienceThe current paper analyses spectrographic data of two-consonant sequences with one or both consonants identified, omitted or changed into another consonant, with one or two features identified or with no feature identified, when compared to an earlier perception analysis. Perceptual and acoustic data mostly correspond, proving that consonants had indeed been changed, significantly reduced or deleted, mainly in coda position and in non-final phrase syllables, thereby preserving acoustic information crucial for lexical access, integration of prosodic structure and successful communication

Modelling Aspects of Reduction and Assimilation of consonant sequences in Spontaneous French Speech

International audienceThe following paper presents spectrographic data of consonant sequences containing one or two consonants omitted and/or changed into another consonant when compared to an existing perception analysis. In most cases, perceptual and acoustic data are shown to strongly correspond, proving that consonants had indeed been changed, significantly reduced or deleted, mainly in a weak position, thereby preserving acoustic information crucial for lexical access, integration of prosodic structure and successful communication. Tentative rules summarise the tendencies observed in reduction and assimilation patterns

Acoustic analysis of occlusive weakening in Parkinsonian French speech

International audienceThe current study investigated selected acoustic characteristics of the weakening of occlusives (O's) in French Parkinsonian Speech (PS). The results confirm an increase in the reduction of O's in PS compared to control speech (CS). In PS, O's have a significantly decreased intervocalic energy level, slightly shorter realisations and a higher number of visible formants and noise; the number of burstless and omitted O's is also higher. However, weakening patterns vary between different consonants and are strongly dependent on voicing and place. Occlusive weakening, a consequence of Parksinson's disease production deficits, appears to be influenced by the inherent-articulatory characteristics of consonants

Consonant and Vowel Duration in Parkinsonian French Speech

International audienceThe current study compared vowel and consonant duration in speech read by 10 French Parkinsonian speakers and 10 control speakers. The results show a different impact of Parkinson's disease (PD) on speech segments. Consonants were shortened in PD speech while vowels were significantly longer. This results from the concomitance of articulatory movements of reduced amplitude and orofacil bradykinesia. As a consequence syllabic productions are of the overall duration in PD speech as in normal speech. The durational contrast of consonants was maintained, although for vowels there was less agreement with the normal pattern of intrinsic durations, especially for high vowels

Acoustic Properties of Consonant Sequences in Conversational French Speech

International audienceThe current paper analyses spectrographic data of two-consonant sequences with one or both consonants identified, omitted or changed into another consonant, with one or two features identified or with no feature identified, when compared to an earlier perception analysis. Perceptual and acoustic data mostly correspond, proving that consonants had indeed been changed, significantly reduced or deleted, mainly in coda position and in non-final phrase syllables, thereby preserving acoustic information crucial for lexical access, integration of prosodic structure and successful communication