Model-order selection in Zernike polynomial expansion of corneal surfaces using the efficient detection criterion

Corneal-height data are typically measured with videokeratoscopes and modeled using a set of orthogonal Zernike polynomials. We address the estimation of the number of Zernike polynomials, which is formalized as a model-order selection problem in linear regression. Classical information-theoretic criteria tend to overestimate the corneal surface due to the weakness of their penalty functions, while bootstrap-based techniques tend to underestimate the surface or require extensive processing. In this paper, we propose to use the efficient detection criterion (EDC), which has the same general form of information-theoretic-based criteria, as an alternative to estimating the optimal number of Zernike polynomials. We first show, via simulations, that the EDC outperforms a large number of information-theoretic criteria and resampling-based techniques. We then illustrate that using the EDC for real corneas results in models that are in closer agreement with clinical expectations and provides means for distinguishing normal corneal surfaces from astigmatic and keratoconic surfaces.

Independent review of ACT Corrective Services Alexander Maconochie Centre [Interim Report]

Under a Services Agreement dated 16th April 2010 the Australian Capital Territory (ACT) engaged Knowledge Consulting Pty Ltd to conduct an independent review of operations at the Alexander Maconochie Centre (AMC) in the ACT. The Review was commissioned following a motion passed in the ACT Legislative Assembly as follows: “That this Assembly: (1) notes: (a) concerns regarding the operation of the AMC; (b) the unanimous findings of the Standing Committee on Justice and Community Safety report, Inquiry into the delay in the commencement of operations at the Alexander Maconochie Centre; and (c) the Government’s intention to have a review into the operation of the AMC after its first year of operation; and (2) calls on the Government to: (a) commission an independent reviewer to conduct the one year review into the AMC; (b) ensure that the review be open and transparent and public, and include input from community and non-government groups with an interest or involvement in the AMC, including on the terms of reference for the review; (c) ensure the review is completed in a timely manner and be tabled in the Legislative Assembly immediately upon completion; and (d) report upon the progress of the review in August 2010;”

Higher-Order spectra of nonlinear polynomial models for Chua's circuit

Polynomial models are shown to simulate accurately the quadratic and cubic nonlinear interactions (e.g. higher-order spectra) of time series of voltages measured in Chua's circuit. For circuit parameters resulting in a spiral attractor, bispectra and trispectra of the polynomial model are similar to those from the measured time series, suggesting that the individual interactions between triads and quartets of Fourier components that govern the process dynamics are modeled accurately. For parameters that produce the double-scroll attractor, both measured and modeled time series have small bispectra, but nonzero trispectra, consistent with higher-than-second order nonlinearities dominating the chaos.

Book Review: "Mark Considine, Jenny Lewis and Damon Alexander Networks, Innovation and Public Policy : Politicians, Bureaucrats and the Pathways to Change inside Government Houndsmills, UK: Palgrave Macmillan, 2009"

Having wrung the most from workforce and workplace productivity initiaitves, innovation has come to the fore as a key goal and directive for public sector organisations to become more efficient. This clarion call for innovation can be heard all around the world, with public services everywhere taking up the message to develop better, smarter, novel, more innovative processes, programs and policies. In the current push for innovation, networks are considered to be a superior vehicle through which collective knowledge can be shared and leveraged; replacing or at least supplementing the role function previously provided by inventive leaders...

Decomposition construction for secret sharing schemes with graph access structures in polynomial time

The purpose of this paper is to describe a new decomposition construction for perfect secret sharing schemes with graph access structures. The previous decomposition construction proposed by Stinson is a recursive method that uses small secret sharing schemes as building blocks in the construction of larger schemes. When the Stinson method is applied to the graph access structures, the number of such “small” schemes is typically exponential in the number of the participants, resulting in an exponential algorithm. Our method has the same flavor as the Stinson decomposition construction; however, the linear programming problem involved in the construction is formulated in such a way that the number of “small” schemes is polynomial in the size of the participants, which in turn gives rise to a polynomial time construction. We also show that if we apply the Stinson construction to the “small” schemes arising from our new construction, both have the same information rate.

An accuracy assessment of ASTER stereo images-derived digital elevation model by using rational polynomial coefficient model

The along-track stereo images of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor with 15 m resolution were used to generate Digital Elevation Model (DEM) on an area with low and near Mean Sea Level (MSL) elevation in Johor, Malaysia. The absolute DEM was generated by using the Rational Polynomial Coefficient (RPC) model which was run on ENVI 4.8 software. In order to generate the absolute DEM, 60 Ground Control Pointes (GCPs) with almost vertical accuracy less than 10 meter extracted from topographic map of the study area. The assessment was carried out on uncorrected and corrected DEM by utilizing dozens of Independent Check Points (ICPs). Consequently, the uncorrected DEM showed the RMSEz of ± 26.43 meter which was decreased to the RMSEz of ± 16.49 meter for the corrected DEM after post-processing. Overall, the corrected DEM of ASTER stereo images met the expectations.