An off-line large vocabulary hand-written Chinese character recognizer

An off-line hand-written Chinese character recognizer based on contextual vector quantization (CVQ) supporting a vocabulary of 4616 Chinese characters, alphanumerics and punctuation symbols has been reported. Trained with a sample for each character from each of 100 writers and tested on texts of 160000 characters written by another 200 writers, the average recognition rate is 77.2%. Two statistical language models have been investigated in this study. Their performance in terms of their capabilities in upgrading the recognition rate by 8.8% and 12.0% respectively when used as post-processors of the recognizer are reported.published_or_final_versio

A continuous Putonghua recognizer

A multi-speaker continuous Putonghua recognizer has been developed composing of 20 speaker-dependent recognizer as sub-systems. Each sub-system is a network of hidden Markov models modeling triphones as the fundamental speech units. Over 3 GB of speech data have been collected for training from twenty native Putonghua speakers reading carefully designed tests trying to include all phone-to-phone transitions in Putonghua. A Viterbi path search yields the best speech unit sequence over the HMMnet for each unknown input utterance which is then passed down to a language model for post-processing. The most suitable word sequence is determined by means of the bigram statistics of 470 word classes covering a vocabulary of over 80,000 words. An enrollment process is required for each new user to select the most suitable speaker-dependent system among the 20 sub-systems according to their recognition performance on a small quantity of speech data collected from the user.published_or_final_versio

Ahmed glaucoma valves in refractory glaucoma: A 7-year audit

Purpose: To present the long-term results of Ahmed glaucoma valve (AGV) implantation. Methods: Consecutive case series of 94 eyes with AGV implantation over 7 years. Temporary tube ligation with C3F8 gas fill was used in high-risk eyes (group G&L) and compared with standard implantation in both phakic (group A) and pseudophakic/aphakic eyes (group B). Success was intraocular pressure (IOP) of 6 mm Hg or greater and 21 mm Hg or less and/or IOP reduction of 20% or greater. Results: Average follow-up was 28.9±20.3 months. The mean preoperative IOP changed from 30.8±8.2 to 19.7±7.6 mm Hg and mean preoperative medications changed from 3.3±1.2 to 1.2±1.1 at the final visit. Cumulative probability of survival at 1 and 4 years was 89.1% and 72.9%. There was no statistically significant difference in success between the three groups, but complications due to postoperative hypotony (six eyes) only occurred in group B. Other complications were corneal decompensation (three eyes), tube erosion (six eyes) and aqueous misdirection (four eyes). Conclusions: AGV implantation offered good long-term IOP control with a success rate of 78.7%. The authors recommend C3F8 gas fill and temporary tube ligation in eyes at high risk of postoperative hypotony and the use of donor sclera or human pericardial patch to prevent tube erosion.published_or_final_versio

Secondary production and diet of an invasive snail in freshwater wetlands: Implications for resource utilization and competition

Invasive species can monopolize resources and thus dominate ecosystem production. In this study we estimated secondary production and diet of four populations of Pomacea canaliculata, a freshwater invasive snail, in wetlands (abandoned paddy, oxbow pond, drainage channel, and river meander) in monsoonal Hong Kong (lat. 22°N). Apple snail secondary production (ash-free dry mass [AFDM]) ranged from 165.9 to 233.3 g m-2 year-1, and varied between seasons. Production was lower during the cool dry northeast monsoon, when water temperatures might have limited growth, but fast growth and recruitment of multiple cohorts were possible throughout much (7-10 months) of the year and especially during the warm, wet southwest monsoon. The diet, as revealed by stomach-content analysis, consisted mainly of detritus and macrophytes, and was broadly consistent among habitats despite considerable variation in the composition and cover of aquatic plants. Apple snail annual production was >10 times greater than production estimates for other benthic macroinvertebrates in Hong Kong (range 0.004-15 g AFDM m-2 year-1, n = 29). Furthermore, annual production estimates for three apple snail populations (i. e. >230 g AFDM m-2 year-1) were greater than published estimates for any other freshwater snails (range 0.002-194 g AFDM m-2 year-1, n = 33), regardless of climatic regime or habitat type. High production by P. canaliculata in Hong Kong was attributable to the topical climate (annual mean ~24°C), permitting rapid growth and repeated reproduction, together with dietary flexibility including an ability to consume a range of macrophytes. If invasive P. canaliculata can monopolize food resources, its high productivity indicates potential for competition with other macroinvertebrate primary consumers. Manipulative experiments will be needed to quantify these impacts on biodiversity and ecosystem function in wetlands, combined with management strategies to prevent further range extension by P. canaliculata. © Springer Science+Business Media B.V. 2009.published_or_final_versionSpringer Open Choice, 01 Dec 201

Properties of a hand-printed Chinese character recognizer based on contexted vector quantization

A hand-printed Chinese character recognizer based on Contextual Vector Quantization (CVQ) has been built previously. In this paper, several properties of the recognizer will be discussed and the recognizer of 4516 Chinese characters has a successful rate of 91.0%. Then the output of the recognizer is passed to a language model which when applied to recognize a passage of about 1200 characters raises the rate from 91.5% to 97.5%.published_or_final_versio

Thermal-diffusivity measurements of an oriented superconducting-film–substrate composite using the mirage technique

When one measures the thermal diffusivity χ of a thin film on a substrate by the mirage method, the photothermal deflection of the probe beam is caused by the heat field contributed by both the film and the substrate which are heated by the pump beam. To include the effects due to the presence of the substrate, we present a method to measure the diffusivities of both the film and substrate in one set of mirage detection. Using the off-axis magnetron sputtering process, we fabricated YBa2Cu3O7-δ thin films of suitable thickness (∼60 nm) on SrTiO3 as our sample for χ measurements along the c and b axes. Our results are consistent with published ones.published_or_final_versio

Purpurin Triggers Caspase-Independent Apoptosis in Candida dubliniensis Biofilms

Candida dubliniensis is an important human fungal pathogen that causes oral infections in patients with AIDS and diabetes mellitus. However, C. Dubliniensis has been frequently reported in bloodstream infections in clinical settings. Like its phylogenetically related virulent species C. albicans, C. Dubliniensis is able to grow and switch between yeast form and filamentous form (hyphae) and develops biofilms on both abiotic and biotic surfaces. Biofilms are recalcitrant to antifungal therapies and C. Dubliniensis readily turns drug resistant upon repeated exposure. More than 80% of infections are associated with biofilms. Suppression of fungal biofilms may therefore represent a viable antifungal strategy with clinical relevance. Here, we report that C. dubliniensis biofilms were inhibited by purpurin, a natural anthraquinone pigment isolated from madder root. Purpurin inhibited C. dubliniensis biofilm formation in a concentration-dependent manner; while mature biofilms were less susceptible to purpurin. Scanning electron microscopy (SEM) analysis revealed scanty structure consisting of yeast cells in purpurin-treated C. dubliniensis biofilms. We sought to delineate the mechanisms of the anti-biofilm activity of purpurin on C. Dubliniensis. Intracellular ROS levels were significantly elevated in fungal biofilms and depolarization of MMP was evident upon purpurin treatment in a concentration-dependent manner. DNA degradation was evident. However, no activated metacaspase could be detected. Together, purpurin triggered metacaspase-independent apoptosis in C. dubliniensis biofilms.published_or_final_versio

Modelling and prediction of particulate matter, NOx, and performance of a diesel vehicle engine under rare data using relevance vector machine

2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Development of metal-containing polymers for optoelectronic applications

Most of the work in organic electroluminescent polymers has been focused on organic conjugated polymers. However, polymers attached with transition metal complex have received relatively less attention. We have synthesized and studied the light emitting properties of some metal containing polymers based on the polypyridine complexes of rhenium and ruthenium. These complexes exhibit long-lived excited states caused by the metal to ligand charge transfer transitions. By varying the structure of the ligand and/or the transition metal, we are able to fine-tune the electronic properties of the resulting metal complexes.We have synthesized a series of poly(phenylenevinylene) (PPV) derivatives which are functionalized with ruthenium polypyridine complexes at the polymer mainchain or side chain. These complexes are able to act as photosensitizers which enhance the photoconductivity of these polymers at longer wavelength. Both the conjugatedbackbone and the metal complex can emit light upon excitation. As a result, it is possible to tune the color by loading different amount of ruthenium complex to the polymer. Luminescence studies showed that the ruthenium complex could quench the emission of the conjugated backbone in some polymers, which suggests an energy transfer processbetween the backbone and the metal complexes. It was also found that the presence of metal complexes could enhance the charge carrier mobilities of the polymers, as the metal and/or ligands can act as extra charge carriers in the charge transport process.published_or_final_versio