William J. Fitzgerald

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Bright and dark flashes are typical artifacts in degraded motion picture material. The distortion is referred to as "dirt and sparkle" in the motion picture industry. This is caused either by dirt becoming attached to the frames of the film, or by the film material being abraded. The visual result is random patches of the frames having grey level values(More)
We propose some Bayesian methods to address the problem of fitting a signal modeled by a sequence of piecewise constant linear (in the parameters) regression models, for example, autoregressive or Volterra models. A joint prior distribution is set up over the number of the changepoints/knots, their positions, and over the orders of the linear regression(More)
This paper presents a number of model based interpolation schemes tailored to the problem of interpolating missing regions in image sequences. These missing regions may be of arbitrary size and of random, but known, location. This problem occurs regularly with archived film material. The film is abraded or obscured in patches, giving rise to bright and dark(More)
The core/periphery structure is ubiquitous in network studies. The discrete version of the concept is that individuals in a group belong to either the core, which has a high density of ties, or to the periphery, which has a low density of ties. The density of ties between the core and the periphery may be either high or low. If the core/periphery structure(More)
In this paper, application of particle filtering techniques to different classes of problems arising in digital communications is considered. Several approaches are reviewed, and a brief simulation study for demodulation in fading conditions and joint symbol/channel coefficients/code delay estimation for DS spread-spectrum systems is carried out.
Cellular traffic is a central aspect of cell function in health and disease. It is highly dynamic, and can be investigated at increasingly finer temporal and spatial resolution due to new imaging techniques and probes. Manual tracking of these data is labor-intensive and observer-biased and existing automation is only semi-automatic and requires(More)
When diagonal values are missing or excluded, MINRES is a natural continuous model for the core/periphery structure of a symmetric social network matrix. Symmetric models, however, are not so useful when dealing with asymmetric data. Singular value decomposition (SVD) is a natural choice to model asymmetry, but this method also requires the presence of(More)
In this paper, we introduce a new analytical model for the α-stable probability density function (p.d.f). The new model is based on a corollary of the mixing theorem for symmetric α-stable (SαS) random variables (r.v.) [1] which states that a SαS r.v. can be expressed as the product of a Gaussian r.v. and a positive-stable r.v.(More)
The T cell receptor (TCR) expressed on most T cells is a protein complex consisting of TCRalphabeta heterodimers that bind antigen and cluster of differentiation (CD) 3epsilondelta, epsilongamma, and zetazeta dimers that initiate signaling. A long-standing controversy concerns whether there is one, or more than one, alphabeta heterodimer per complex. We(More)