Search results for: J.M. Walsh

Professional education can be a stressful experience for some individuals, and may impact negatively on emotional well-being and academic performance. Psychological morbidity and associated sources of stress have not been investigated extensively in physiotherapy students. This study explored sources of stress, psychological morbidity and possible associations between these variables in undergraduate...

chapter

A recursive construction of the set of binary entropy vectors

J.M. Walsh, S. Weber

2009 47th Annual Allerton Conference on Communication, Control, and Computing (Allerton) > 545 - 552

2009 47th Annual Allerton Conference on Communication, Control, and Computing (Allerton 2009)

The primary contribution is a finite terminating algorithm that determines membership of a candidate entropy vector in the set of binary entropy vectors ??_N. We outline the relationship between ??_N and its unbounded cardinality discrete random variable counterpart ????_N*or its normalization ????_N*). We discuss connections between ??_N and ????_N*. For example, for any outer bound, say the Shannon outer...

chapter

Belief propagation distributed estimation in sensor networks: An optimized energy accuracy tradeoff

J.M. Walsh, P.A. Regalia

2008 IEEE International Conference on Acoustics, Speech and Signal Processing > 2297 - 2300

ICASSP 2008. IEEE International Conference on Acoustic, Speech and Signal Processes

The estimation error performance of Gaussian belief propagation based distributed estimation in a large sensor network employing random sleep strategies is explicitly evaluated for a simple model using density evolution analysis. Both regular sleep strategies, in which the number of nodes awake at any time instant is fixed, as well as irregular sleep strategies, in which the number of awake nodes...

chapter

Expectation propagation for distributed estimation in sensor networks

J.M. Walsh, P.A. Regalia

2007 IEEE 8th Workshop on Signal Processing Advances in Wireless Communications > 1 - 5

2007 IEEE 8th Workshop on Signal Processing Advances in Wireless Communications

We show that the expectation propagation (EP) family of algorithms constitute a natural choice for distributed estimation and detection in sensor networks. In particular, random sleep strategies, which are commonly chosen to ensure robustness, equal power dissipation across the network, and ease of deployment, espouse a sparse dependence structure among the parameters to be estimated. This sparse...

chapter

Density Evolution for Expectation Propagation

J.M. Walsh

2007 IEEE International Conference on Acoustics, Speech and Signal Processing - ICASSP '7 > 2 > II-545 - II-548

2007 IEEE International Conference on Acoustics, Speech, and Signal Processing

Expectation propagation (EP) is a theoretical extension of the belief propagation family of message passing algorithms for statistical inference which allows for efficient handling of models with continuous random variables as well as second or higher order correlation via the use of standard exponential families of probability measures. Here we provide theoretically rigorous justifications for the...

article

Optimality and Duality of the Turbo Decoder

P.A. Regalia, J.M. Walsh

Proceedings of the IEEE > 2007 > 95 > 6 > 1362 - 1377

The near-optimal performance of the turbo decoder has been a source of intrigue among communications engineers and information theorists, given its ad hoc origins that were seemingly disconnected from optimization theory. Naturally one would inquire whether the favorable performance might be explained by characterizing the turbo decoder via some optimization criterion or performance index. Recently,...

chapter

Dual Optimality Frameworks for Expectation Propagation

J.M. Walsh

2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications > 1 - 5

2006 IEEE 7th Workshop on Signal Processing Advances in Wireless Communications

We show a duality relationship between two different optimality frameworks for expectation propagation, a family of algorithms for distributed statistical inference that include belief propagation and the turbo decoder/equalizer as particular examples. Each of the two optimality frameworks may then be used to interpret each other

chapter

Iterative Constrained Maximum Likelihood Estimation Via Expectation Propagation

J.M. Walsh, P.A. Regalia

2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings > 5 > V

2006 IEEE International Conference on Acoustics, Speech, and Signal Processing

Expectation propagation defines a family of algorithms for approximate Bayesian statistical inference which generalize belief propagation on factor graphs with loops. As is the case for belief propagation in loopy factor graphs, it is not well understood why the stationary points of expectation propagation can yield good estimates. In this paper, given a reciprocity condition which holds in most cases,...

article

Turbo Decoding as Iterative Constrained Maximum-Likelihood Sequence Detection

J.M. Walsh, P.A. Regalia, C.R. Johnson

IEEE Transactions on Information Theory > 2006 > 52 > 12 > 5426 - 5437

The turbo decoder was not originally introduced as a solution to an optimization problem, which has impeded attempts to explain its excellent performance. Here it is shown, that the turbo decoder is an iterative method seeking a solution to an intuitively pleasing constrained optimization problem. In particular, the turbo decoder seeks the maximum-likelihood sequence (MLS) under the false assumption...

chapter

A convergence proof for the turbo decoder as an instance of the gauss-seidel iteration

J.M. Walsh, P. Regalia, C.R. Johnson

Proceedings. International Symposium on Information Theory, 2005. ISIT 2005. > 734 - 738

2005 IEEE International Symposium on Information Theory (ISIT)

Many previous attempts at analyzing the convergence behavior of turbo and iterative decoding, such as EXIT style analysis (S. ten Brink, Oct. 2001) and density evolution (H. El Gamal and A. R. Hammons, Jr, Feb. 2001), ultimately appeal to results which become valid only when the block length grows rather large, while still other attempts, such as connections to factor graphs (F. R. Kshischang, et...

article

The effect of investment material and ceramming regime on the surface roughness of two castable glass-ceramic materials

A. Johnson, R. van Noort, P.V. Hatton, J.M. Walsh

Dental Materials > 2003 > 19 > 3 > 218-225

Objective: To assess the surface roughness (R _a ) of two castable glass-ceramic materials, cast using four different investment materials and employing different ceramming regimes.Methods: Forty discs, each 12mm diameter and 2mm thick were produced from two castable glass-ceramic materials, one a glass ionomer derivative based on 1.5SiO ₂ -1Al ₂ O ₃ -0.53P ₂ ...

article

Effect of furnace type and ceramming heat treatment conditions on the biaxial flexural strength of a canasite glass-ceramic

A. Johnson, M.Y. Shareef, R. van Noort, J.M. Walsh

Dental Materials > 2000 > 16 > 4 > 280-284

Objective: To assess the effect of different heat treatment conditions when using two different furnace types on the biaxial flexural strength (BFS) of a fluorcanasite castable glass-ceramic.Methods: Two furnace types, one a programmable furnace (PF), the other a dental laboratory burnout furnace (DLF), were used with various ceramming times to determine their effect on the BFS of a fluorcanasite...

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INFONA - science communication portal

Search results for: J.M. Walsh

EP34.27: The evolution of ultrasound features from a Caesarean scar ectopic to placenta accreta spectrum

OC02.09: Placenta accreta spectrum ultrasound stage and fetal growth

VP04.03: Assessment of maternal anxiety among women undergoing an early comprehensive fetal anatomy scan

OC08.01: Placenta accreta spectrum prenatal ultrasound grade and association with clinical outcomes

VP24.09: First trimester screening for open spina bifida: validation of measurement technique of the posterior fossa landmarks for open spina bifida

EP14.06: Prenatal diagnosis, management and outcome of fetal tachyarrhythmia: a 12‐year single centre experience

Pregnancies in older women—it's time to adopt an ‘every woman, every time’ approach to preconception care

1939 Late cardiac effects of chemotherapy in breast cancer survivors treated with adjuvant Doxorubicin: 10-Year follow-up

Sources of stress and psychological morbidity among undergraduate physiotherapy students

A recursive construction of the set of binary entropy vectors

Belief propagation distributed estimation in sensor networks: An optimized energy accuracy tradeoff

Expectation propagation for distributed estimation in sensor networks

Density Evolution for Expectation Propagation

Optimality and Duality of the Turbo Decoder

Dual Optimality Frameworks for Expectation Propagation

Iterative Constrained Maximum Likelihood Estimation Via Expectation Propagation

Turbo Decoding as Iterative Constrained Maximum-Likelihood Sequence Detection

A convergence proof for the turbo decoder as an instance of the gauss-seidel iteration

The effect of investment material and ceramming regime on the surface roughness of two castable glass-ceramic materials

Effect of furnace type and ceramming heat treatment conditions on the biaxial flexural strength of a canasite glass-ceramic

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