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Science and, United States

Weinberg G.V.,Defence Science and Technology Group
Digital Signal Processing: A Review Journal | Year: 2016

Recently a transformation approach for noncoherent radar detector design has been introduced, where the classical constant false alarm rate detectors for Exponentially distributed clutter are modified to operate in any clutter intensity model of interest. Recent applications of this approach have introduced new decision rules for target detection in Pareto and Weibull distributed clutter. These transformed detectors tended to lose the constant false alarm rate property with respect to one of the clutter parameters. A closer examination of this transformation process yields conditions under which the constant false alarm rate property can be retained. Based upon this, a new model for X-band maritime radar returns is investigated, and corresponding detectors are developed. The relative merits of this new development are investigated with synthetic and real X-band data. Crown Copyright © 2016 Published by Elsevier Inc. All rights reserved.

Taylor R.,Defence Science and Technology Group
Operations Research Letters | Year: 2016

For any given ϵ>0 we provide an algorithm for the Quadratic Knapsack Problem that has an approximation ratio within O(n2/5+ϵ) and a run time within O(n9/ϵ). © 2016 Published by Elsevier B.V. All rights reserved.

Bocquet S.,Defence Science and Technology Group
Electronics Letters | Year: 2015

Closed-form parameter estimators are obtained for Pareto distributed clutter with noise. The estimators consist of simple combinations of data moments, with no special functions, but they are only applicable to multilook data, because they make use of the harmonic mean, which is zero for the single-look clutter plus noise distribution. They have been tested on simulated two-look clutter and noise data. The closed-form estimators have about the same accuracy as the numerically solved z log z estimators obtained in previous work, but they are much simpler and quicker to compute. © Crown 2015.

Weinberg G.V.,Defence Science and Technology Group
Digital Signal Processing: A Review Journal | Year: 2016

This paper introduces a new variation of the p-norm detector, which is designed for application to coherent multilook detection in compound Gaussian clutter with inverse Gamma texture. By applying what is termed a compensator, enhanced detection performance can be achieved independently of the number of looks used. This is particularly useful in the case of a fast scan rate radar where the number of looks may be quite small. Conventional coherent detectors tend to experience saturation in such scenarios, and so this new detection process complements recent advances in this area. Further validation is provided by applying this new decision rule to synthetic target detection in real X-band radar clutter. Crown Copyright © 2016 Published by Elsevier Inc. All rights reserved.

Thirkettle-Watts D.,Defence Science and Technology Group
Biochemistry and Biophysics Reports | Year: 2016

The mu opioid receptor is a G-protein coupled receptor able to signal through the Gαi /o class of G-protein and β-arrestin pathways, stimulating down-stream effector pathways. Signaling bias occurs when different receptor agonists lead to different signaling outcomes. Traditionally these have been studied using end-point assays. Real-time cellular analysis platforms allow for the analysis of the holistic effects of receptor activation as an integrated output. While this allows for different ligands to be compared rapidly, the cellular mechanisms underlying the signal are not well described. Using an impedance based system, the impedance responses for two opioid ligands, morphine and DAMGO were examined.The impedance responses for these two agonists, while showing similar features, were distinct from each other. Some of the mechanisms underlying the mu opioid receptor coupled impedance changes were investigated. It was found that the response is a result of discrete cellular processes, including G-protein signaling and protein kinase phosphorylation. © 2016 .

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