Phosphorescent metal complexes can be incorporated into amyloid-like fibrils, and these fibrils can be decorated with conjugated polyelectrolytes (CPEs). In this study, fac-tris[2-phenylpyridinato-C2,N]irdium(III) complexes [Ir(piq)3] were used as the phosphorescence emitter and Sodium-poly(3-thiophene acetic acid) (PTAA-Na) compounds were used as CPEs. Herein we study the energy transfer processes between the iridium complexes and the CPEs. To investigate these mechanisms, the analysis of the emission quenching and time-resolved measurements were done. Our measurements show that energy can be transfered from singlet state of PTAA to the singlet state of Ir(piq)3. Moreover, incorporation of iridium into amyloid fibrils decreases the importance of energy transfer by the Dexter mechanism. Finally we propose a geometry of interaction to explain the obtained results.

This thesis focuses on investigations of transient dark states of fluorescentmolecules using spectroscopic techniques. The main purpose is to show andconvince the reader that transient dark states are not always a nuisance, butalso represent an additional source of information. Several studies with fluorescencecorrelation spectroscopy were performed, all related to non-fluorescentstates such as triplet state or isomerized states.Photobleaching is one of the main problems in virtually all of the fluorescencetechniques. In this thesis, mechanisms that retard photobleaching arecharacterized. Several compounds, antioxidants and triplet state quenchers,which decrease photobleaching, are studied, and guidelines for achieving optimalfluorescence brightness using these compounds are presented.Triplet state quenching by several compounds was studied. Detailed investigationsof the fluorescence quencher potassium iodide demonstratedthat for some of fluorophores, except of quenching, there is fluorescence enhancementmechanism present. In agreement with the first publication inthis thesis, antioxidative properties were found to play an important role inthe fluorescence enhancement. Quenching of the triplet state is proposedas a tool for monitoring diffusion mediated reactions over a wide range offrequencies.Specially designed fluorophores combining high triplet yields with reasonablefluorescence brightness and photostability were characterized forpossible applications in novel super-resolution imaging techniques based onfluorescence photoswitching. Except of benefits for imaging techniques, photoinducedswitching to non-fluorescent states could be used for monitoringmolecular diffusion, which was also demonstrated in this thesis.Studies of the triplet state kinetics of fluorophores close to dielectric interfaceswere performed using fluorescence spectroscopy. The analysis of thetriplet state kinetic can provide information about the local microenvironmentand electrostatic interactions near dielectric interfaces. / QC 20100414

No description available.

Face detection and pose estimation are two widely studied problems - mainly because of their use as subcomponents in important applications, e.g. face recognition. In this thesis I investigate a new approach to the general problem of object detection and pose estimation and apply it to faces. Face detection can be considered a special case of this general problem, but is complicated by the fact that faces are non-rigid objects. The basis of the new approach is the use of scale and orientation invariant feature structures - feature triplets - extracted from the image, as well as a biologically inspired associative structure which maps from feature triplets to desired responses (position, pose, etc.). The feature triplets are constructed from curvature features in the image and coded in a way to represent distances between major facial features (eyes, nose and mouth). The final system has been evaluated on different sets of face images.

No description available.

<p>Face detection and pose estimation are two widely studied problems - mainly because of their use as subcomponents in important applications, e.g. face recognition. In this thesis I investigate a new approach to the general problem of object detection and pose estimation and apply it to faces. Face detection can be considered a special case of this general problem, but is complicated by the fact that faces are non-rigid objects. The basis of the new approach is the use of scale and orientation invariant feature structures - feature triplets - extracted from the image, as well as a biologically inspired associative structure which maps from feature triplets to desired responses (position, pose, etc.). The feature triplets are constructed from curvature features in the image and coded in a way to represent distances between major facial features (eyes, nose and mouth). The final system has been evaluated on different sets of face images.</p>

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 81-86).

published_or_final_version / Chemistry / Master / Master of Philosophy

Hearing loss has a prevalence of 10.3% in New Zealand, with the Māori population being disproportionately affected compared to the non-Māori population. Hearing loss is an impairment that is under-recognised, under-reported and under-treated. This can be explained by the many existing barriers – the shortage of audiological services, financial cost to an individual seeking treatment, the stigma of both hearing loss and hearing aids, and healthcare seeking rates, particularly among the Māori population. This study aimed to develop a Māori language adaptive digit triplet test that could be offered remotely via the telephone and Internet as a hearing-screening test. Three sets of recordings were made of digit triplets spoken in te reo Māori by a female speaker. Two of these sets were selected for normalisation in speech noise. Normal-hearing participants (8 listeners) with hearing thresholds ≤20 dB HL were tested to establish the intelligibility of the individual recorded digits at various signal-to-noise ratios (-13, -10.5, -8 and -5.5 dB). Psychometric functions were fitted to the intelligibility data, and the digits in each position of the triplet that had the steepest slope were selected as the final test stimuli. The level of each selected digit was then adjusted to achieve equal intelligibility as measured at the midpoints of the psychometric functions. These digits were then assembled into eight equivalent lists of similar difficulty, ready for pilot testing. Due to low participant numbers, the pilot testing phase was not completed. Further development of this test continues as the focus of a follow-on study.

Presbycusis, or age-related hearing loss, is one of the most common chronic conditions to affect adults. On average individuals wait seven years from the time they notice a hearing impairment to the time they seek help from a hearing professional. This delay may have wide reaching implications for public health in the coming decades, as aging populations become more prevalent and as further research assesses the relationship between hearing loss and mental health conditions such as depression and dementia. The development of the New Zealand Hearing Screening Test (NZHST) aims to fulfil a need for a robust hearing screening test that individuals can access from home. This digit triplet test (DTT) will be particularly valuable for those in rural areas where audiological services are sparse and for those who have mobility issues which restrict attendance at clinical appointments. In order to accommodate as many New Zealanders as possible, the NZHST will have two versions, an internet version and a land-line telephone version; both of which can be delivered into their home in either New Zealand English or Te Reo Māori. This research is the third instalment in the development of the NZHST. The current research is divided into three parts; the verification of the New Zealand English DTT for the internet version, the pilot study for the Te Reo Māori DTT for the internet version, and the normalisation of the New Zealand English DTT for the telephone version. In the verification process, 50 individuals with various audiometric thresholds listened to 3 lists of 27 New Zealand English digit triplets, presented in three conditions; binaurally and to each ear separately via an internet interface. In the pilot study, 27 participants with various audiometric thresholds listened to 3 lists of 27 Te Reo Māori digit triplets via a software interface on a laptop computer. The normalisation process involved 10 individuals with normal hearing (average air-conduction pure tone thresholds of ≤ 20 dB HL) listening to 168 New Zealand English digit triplets under two different noise conditions; one as continuous speech noise and the other a noise with spectral and temporal gaps (STG noise) presented via a software interface on a laptop computer. Four conditions of the 168 digits were presented; once to each ear for the continuous noise, and once to each ear for the STG noise. Significant correlations were found between the binaural DTT and PTA (R = 0.66), and between the monaural ear DTT and PTA (R = 0.73) for the verification. The binaural DTT had a test sensitivity of 94% and a specificity of 88%. Pilot study correlation between binaural DTT and PTA was R = 0.61, and was R = 0.63 between monaural DTT and PTA; while the binaural sensitivity (100%) and specificity (100%) of the Te Reo DTT was affected by the very small number of participants with hearing loss (n = 4). The normalisation revealed that detection of the digit triplets was easier when STG noise (Lmid = -11.5 dB SNR, SD = 1.6 dB) was used as a masker, rather than continuous noise (Lmid = -8.9 dB SNR, SD = 1.4 dB).