We propose a non-linear extension of the Fierz-Pauli mass for the graviton through a functional of the vielbein and an external Minkowski background. The functional generalizes the notion of the measure, since it reduces to a cosmological constant if the external background is formally sent to zero. Such a term and the explicit external background, emerge dynamically from a bi-gravity theory, having both a massless and a massive graviton in its spectrum, in a specific limit in which the massless mode decouples, while the massive one couples universally to matter. We investigate the massive theory using the Stückelberg method and providing a 't Hooft-Feynman gauge fixing in which the tensor, vector and scalar Stückelberg fields decouple. We show that this model has the softest possible ultraviolet behavior which can be expected from any generic (Lorentz invariant) theory of massive gravity, namely that it becomes strong only at the scale Λ 3 = (m 2 g M P ) 1/3 .

We study a scalar lattice model for inter-grain forces in static, non-cohesive, granular materials, obtaining two primary results. (i) The applied stress as a function of overall strain shows a power law dependence with a nontrivial exponent, which moreover varies with system geometry. (ii) Probability distributions for forces on individual grains appear Gaussian at all stages of compression, showing no evidence of exponential tails. With regard to both results, we identify correlations responsible for deviations from previously suggested theories.

We compute the nonperturbative decay of supersymmetric flat directions due to their D-term potential. Flat directions can develop large vacuum expectation values during inflation, and, if they are long-lived, this can strongly affect the reheating and thermalization stages after the inflation. We study a generic system of two Uð1Þ or SUð2Þ flat directions which are cosmologically evolving after inflation. After proper gauge fixing, we show that the excitations of the fields around this background can undergo exponential amplification, at the expense of the energy density of the flat directions. We compute this effect for several values of the masses and the initial vacuum expectation values of the two flat directions, through a combination of analytical methods and extensive numerical simulations.

In manual-cued speech (MCS) a speaker produces hand gestures to resolve ambiguities among speech elements that are often confused by speechreaders. The shape of the hand distinguishes among consonants; the position of the hand relative to the face distinguishes among vowels. Experienced receivers of MCS achieve nearly perfect reception of everyday connected speech. MCS has been taught to very young deaf children and greatly facilitates language learning, communication, and general education. This manuscript describes a system that can produce a form of cued speech automatically in real time and reports on its evaluation by trained receivers of MCS. Cues are derived by a hidden markov models (HMM)-based speaker-dependent phonetic speech recognizer that uses context-dependent phone models and are presented visually by superimposing animated handshapes on the face of the talker. The benefit provided by these cues strongly depends on articulation of hand movements and on precise synchronization of the actions of the hands and the face. Using the system reported here, experienced cue receivers can recognize roughly two-thirds of the keywords in cued low-context sentences correctly, compared to roughly one-third by speechreading alone (SA). The practical significance of these improvements is to support fairly normal rates of reception of conversational speech, a task that is often difficult via SA.

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