4,056 research outputs found

    Descriptive Anatomy and Three-Dimensional Reconstruction of the Skull of the Early Tetrapod Acanthostega gunnari Jarvik, 1952

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    The early tetrapod Acanthostega gunnari is an iconic fossil taxon exhibiting skeletal morphology reflecting the transition of vertebrates from water onto land. Computed tomography data of two Acanthostega skulls was segmented using visualization software to digitally separate bone from matrix and individual bones of the skull from each other. A revised description of cranial and lower jaw anatomy in this taxon based on CT data includes new details of sutural morphology, the previously undescribed quadrate and articular bones, and the mandibular symphysis. Sutural morphology is used to infer loading regime in the skull during feeding, and suggests Acanthostega used its anterior jaws to initially seize prey while smaller posterior teeth were used to restrain struggling prey during ingestion. Novel methods were used to repair and retrodeform the skull, resulting in a three-dimensional digital reconstruction that features a longer postorbital region and more strongly hooked anterior lower jaw than previous attempts while supporting the presence of a midline gap between the nasals and median rostrals

    香港華人多發性硬化症的流行病學研究:問卷調查

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    OBJECTIVE: To study the epidemiology of multiple sclerosis in Hong Kong Chinese. DESIGN: Cross-sectional questionnaire survey. SETTING: Neurology and paediatric neurology departments in Hong Kong from January through June 1999. PARTICIPANTS: All confirmed multiple sclerosis patients. MAIN OUTCOME MEASURES: Demographic data, investigation results, Kurtzke's Expanded Disability Status Scale during the last follow-up visit, number of relapses between 1997 and 1998, and treatments used/currently in use. RESULTS: Fifty-three Chinese multiple sclerosis patients were identified. The prevalence was thus estimated to be 0.77 per 100,000 population. This low prevalence was also noted in other multiple sclerosis studies from South-East Asia (range, 0.8-4 per 100,000 population). The female to male ratio among the Chinese multiple sclerosis sufferers was 9.6:1, a figure somewhat higher than that reported in the other studies from South-East Asia (range, 3.2-6.6:1). The Chinese multiple sclerosis patients in this study also had a high spinal cord involvement (66%) and a low presence of cerebrospinal fluid oligoclonal banding (40%). These findings were different from those in Caucasian multiple sclerosis patients. CONCLUSION: Multiple sclerosis in Hong Kong Chinese has a low prevalence, a high female to male ratio, and a low cerebrospinal fluid oligoclonal banding presence.published_or_final_versio

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

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    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

    A novel approach to circuit-field-torque coupled time stepping finite element modeling of electric machines

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    Author name used in this publication: S. L. HoAuthor name used in this publication: W. N. FuAuthor name used in this publication: H. C. WongH.C. Wong, Industrial Centre2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    An effective method to reduce the computing time of nonlinear time-stepping finite-element magnetic field computation

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    Author name used in this publication: W. N. FuAuthor name used in this publication: S. L. HoAuthor name used in this publication: H. C. Wong2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Psychosocial perception of adults with onychomycosis: a blinded, controlled comparison of 1,017 adult Hong Kong residents with or without onychomycosis

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    BACKGROUND: A survey was conducted amongst 1,017 Hong Kong residents ages 18 and over to determine their knowledge of fungal nail infections (onychomycosis) and the psychosocial impact of the disease on the relationships, social lives and careers of sufferers. METHODS: The Fungal Nail Perception Survey was conducted by email and online between May 29th and June 10th, 2013. Participants were shown three photographs of people with and without onychomycosis of the toenails. Respondents were asked ten questions (repeated for each picture) to ascertain their perceptions of the people in the pictures. Questions were related to perceptions around the ability of sufferers and non-sufferers to form relationships with others, social activities of sufferers and non-sufferers, perceptions of the effect of the disease on the potential for career success, and awareness of fungal nail disease and health. The sub-population who themselves suffered from onychomycosis were asked about self-perception as well as their perception of others with onychomycosis. RESULTS: Compared with non-sufferers, survey respondents perceived those with onychomycosis as less likely to be able to form good relationships. They also indicated that they would be more likely to exclude sufferers than non-sufferers from social activities and that they would be more likely to feel uncomfortable when sitting or standing beside an infected person than beside an uninfected person. Respondents perceived people with onychomycosis to be less able to perform well in their chosen career than with someone without onychomycosis. Interestingly, those respondents who themselves were infected felt socially excluded, upset and embarrassed by their infection. CONCLUSIONS: Onychomycosis may lead to stigmatization and social exclusion. Misconceptions of onychomycosis are high and education about the disease needs to be improved. Early recognition and treatment of the disease is essential to avoid complications and improve treatment outcomes, which would lead to reduced psychosocial impact on those with fungal nail infections

    A multislice coupled finite-element method with uneven slice length division for the simulation study of electric machines

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    Author name used in this publication: W. N. FuAuthor name used in this publication: S. L. HoAuthor name used in this publication: H. C. Wong2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Fabrication of Photovoltaic Cell From Rhenium Containing Polymer

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    Photovoltaic devices were fabricated using rhenium bis(arylimino) acenaphthene (DIAN) complex containing poly(p-phenylenevinylene). These polymers absorb strongly in the visible region at ca. 440-550 nm. In addition, this type of transition metal based polymers have been shown to exhibit large photo-sensitivity due to the presence of the rhenium complex, which has a relatively long-lived Metal-to-Ligand Charge Transfer (MLCT) character. By using this type of polymers, the metal content can be adjusted easily by simply changing the monomer feed ratio. Moreover, the excited state properties and electronic absorption properties can be modified by varying the structure of the diimine ligand coordinated to the metal. This approach allows us to fine-tune the absorption spectra of the polymers by employing different types of rhenium complex derivatives. PEDOT:PSS and PTCDI were used as the hole and electron transport layers, respectively. The ITO/PEDOT:PSS/DIAN-PPV/PTCDI/Al devices were found to exhibit photovoltaic response under the illumination of AMI solar radiation. The short-circuit current ISC, open-circuit voltage V OC, and the fill factor FF were measured to be 38 μA/cm 2, 0.93 V and 0.21 respectively. Another photovoltaic device was prepared with the structure ITO/PEDOT:PSS/DIAN-PPV:TiO2/PTCDI/Al and its photovoltaic properties were studied. The presence of TiO2 will assist the electron transport of the DIAN-PPV to the PTCDI, in which the electrons can be collected at the aluminium electrode. The short-circuit current ISC open-circuit voltage VOC, and the fill factor FF were measured to be 51 μA/cm2, 1.18 V and 0.12 respectively. It was observed that the power conversion efficiency of photovoltaic devices related closely to the rhenium content and the structure of the rhenium complex used.published_or_final_versio

    Performance analysis of brushless DC motors including features of the control loop in the finite element modeling

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    Author name used in this publication: S. L. HoAuthor name used in this publication: H. C. WongAuthor name used in this publication: W. N. Fu2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
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