Alexander Sorin

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We develop a systematic algorithm to construct, classify and study exact solutions of type II A/B supergravity which are time–dependent and homogeneous and hence represent candidate cosmological backgrounds. Using the formalism of solvable Lie algebras to represent the geometry of non–compact coset manifolds U/H we are able to reduce the supergravity field(More)
The formalism of integrable mappings is applied to the problem of constructing hierarchies of (1+2) dimensional integrable systems in the (2|2) superspace. We find new supersymmetric integrable mappings and corresponding to them new hierarchies of integrable systems which, at the reduction to the (1|2) superspace, possess N = 2 supersymmetry. The general(More)
We show that eigenvalues of the family of Baxter Q-operators for supersymmetric integrable spin chains constructed with the gl(K|M)-invariant R-matrix obey the Hirota bilinear difference equation. The nested Bethe ansatz for super spin chains, with any choice of simple root system, is then treated as a discrete dynamical system for zeros of polynomial(More)
Phonetic segmentation is an important step in the development of a concatenative TTS voice. This paper introduces a segmentation process consisting of two phases. First, forced alignment is performed using an HMM-GMM model. The resulting segmentation is then locally refined using an SVM based boundary model. Both the models are derived from multi-speaker(More)
This paper describes an efficient sinusoidal modeling framework for high quality wide band (WB) speech synthesis and modification. This technique may serve as a basis for speech compression in the context of small footprint concatenative Text to Speech systems. In addition, it is a useful representation for voice transformation and morphing purposes, e.g.,(More)
BACKGROUND To evaluate the interest of using automatic speech analyses for the assessment of mild cognitive impairment (MCI) and early-stage Alzheimer's disease (AD). METHODS Healthy elderly control (HC) subjects and patients with MCI or AD were recorded while performing several short cognitive vocal tasks. The voice recordings were processed, and the(More)
In multi-form segment synthesis speech is constructed by sequencing speech segments of different nature: model segments, i.e. mathematical abstractions of speech and template segments, i.e. speech waveform fragments. These multi-form segments can have shared, layered or alternate speech parameterization schemes. This paper introduces an advanced uniform(More)
An infinite class of fermionic flows of the N=(1|1) superconformal Toda lattice hierarchy is constructed and their algebraic structure is studied. We completely solve the semi-infinite N=(1|1) Toda lattice and chain hierarchies and derive their tau functions, which may be relevant for building supersymmetric matrix models. Their bosonic limit is also(More)
The general solution of the two–dimensional integrable generalization of the f–Toda chain with fixed ends is explicitly presented in terms of matrix elements of various fundamental representations of the SL(n|n − 1) supergroup. The dominant role of the representation theory of graded Lie algebras in the problem of constructing integrable mappings and(More)