Development of a low-cost automated sample presentation and analysis system for counting and classifying nematode eggs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Mechatronics at Massey University, Manawatu, New Zealand

This thesis discusses the concept development and design of a low-cost, automated, sample presentation system for faecal egg counting, and classification. The system developed uses microfluidics to present nematode eggs for digital imaging to produce images suitable for image analysis and classification. The system costs are kept low by using simple manufacturing methods and commonly available equipment to produce microfluidic counting chambers, which can be interfaced with conventional microscopes. This thesis includes details of the design and implementation of the software developed to allow capture and processing of images from the presentation system. This thesis also includes details on the measures taken to correct for the optical aberrations introduced by the sample presentation system

Hi-precision audio in listening tests - also in the browser?

In listening tests, detailed sound control is sometimes mandatory down to each individual digital sample value and guarantee is needed that they are not unintentionally altered. At other times, a lesser degree of control is acceptable, if on the other hand test execution becomes less restricted. Detailed control of sound is often possible only under “laboratory” conditions where hardware and software are under complete control and sound pressure levels can be accurately calibrated. On the other hand, if test persons can do listening tests at home, via an internet browser for example, collecting large amounts of data becomes faster and cheaper (no laboratory facilities required, and more persons can do tests in parallel). Online listening tests made possible by the Web Audio API offers great flexibility in test execution, but compromises in precise stimulus control must be accepted. This paper analyzes such compromises by discussing technological limitations of Web Audio API followed by validation measurements of sound playback in popular internet browsers. The measurements show that at the detailed level there are significant differences in actual performance of different browsers and behavior is not always as expected. Finally, a solution is presented where audio presentation is delegated to an external audio presenter for situations where the limitations of Web Audio API are not acceptable

Rigorous perturbation theory versus variational methods in the spectral study of carbon nanotubes

Recent two-photon photo-luminescence experiments give accurate data for the ground and first excited excitonic energies at different nanotube radii. In this paper we compare the analytic approximations proved in \cite{CDR}, with a standard variational approach. We show an excellent agreement at sufficiently small radii.Comment: Accepted for publication in Contemporary Mathematic

Perturbative vs. variational methods in the study of carbon nanotubes

Published in: Contemporary Mathematics: "Adventures in Mathematical Physics". Editors: F. Germinet and P. D. Hislop, 2007.International audienceRecent two-photon photo-luminescence experiments give accurate data for the ground and first excited excitonic energies at different nanotube radii. In this paper we compare the analytic approximations proved in [CDR], with a standard variational approach. We show an excellent agreement at sufficiently small radii

Survival of Φ0/2\Phi_{0}/2 periodicity in presence of incoherence in asymmetric Aharonov-Bohm rings

Magneto conductance oscillations periodic in flux with periodicity $\Phi_{0}$ and $\Phi_{0}/2$ are seen in asymmetric Aharonov-Bohm rings as a function of density of electrons or Fermi wave vector. Dephasing of these oscillations is incorporated using a simple approach of wave attenuation. In this work we study how the excitation of the $\Phi_{0}/2$ oscillations and the accompanying phase change of $\pi$ are affected by dephasing. Our results show that the $\Phi_{0}/2$ oscillations survive incoherence, i.e., dephasing, albeit with reduced visibility while incoherence is also unable to obliterate the phase change of $\pi$.Comment: 4 pages, 3 figure