1,016 research outputs found

    Influence of the indirect restoration design on the fracture resistance: a finite element study

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    The roles of Irx3 and Irx5 in mammalian inner ear development

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    Iroquois genes encode a family of transcription factors containing TALE class homeodomain. They are regarded as prepatterning genes in Drosophila sensory organ development. There are six members (Irx1Irx6) of Iroquois genes in mouse and human. Irx3 and Irx5 are linked genes on mouse chromosome 8, which are involved in many mammalian developmental processes. However, the roles of Irx3 and Irx5 in mammalian hearing loss are poorly understood. To identify the function of these two genes in inner ear development, we have investigated two reporter knock‐in mouse mutants: Irx3lacZ, Irx5EGFP, and a double knock‐out mutant: Irx3/5‐/‐. Irx3 and Irx5 have overlapping expression domains in the developing inner ear. Physiological tests indicated that the Irx3lacZ and Irx5EGFP mutant mice displayed hearing defect, while Irx3/5‐/‐ mice were embryonic lethal. Although paint filling analysis showed the normal cochlea morphology of Irx3lacZ and Irx5EGFP mutant mice, ectopic inner hair cells have been discovered in the organ of Corti. Interestingly, the cochlear duct of Irx3/5‐/‐ mice was enlarged and shortened, and the basal part of the cochlea was fused with the saccule. There were also numerous vestibular‐like ectopic hair cells surrounded by ectopic Sox2‐positive cells in the greater epithelial ridge of cochlea. The organ of Corti was malformed with neither hair cell differentiation nor supporting cell differentiation at E16.5. In summary, our results indicate that Irx3 and Irx5 cooperatively pattern the boundary between the vestibule and the cochlea and they are important for the cochlear sensory neural cell specification.postprin

    Individually Frequency Tunable Dual- and Triple-band Filters in a Single Cavity

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    © 2013 IEEE. This paper presents a new class of second-order individually and continuously tunable dual- and triple-band bandpass filters in a single metal cavity. Each passband is realized by two identical metal posts. These dual- and triple-band tunable filters are achieved by putting two or three identical sets of metal-post pair in a single metal cavity. Metal screws are co-designed as a part of the metal posts to control their insertion depth inside the cavity. In this way, the resonant frequencies can be continuously controlled and designed at the desired frequency bands. Moreover, the distance between the two metal posts in a post pair can be freely tuned. Thus, the external quality factor (Qe) and coupling coefficient (k) between the adjacent modes can be easily adjusted to meet the specified requirement in synthesis design. At the bottom of the cavity, some grooves are used to extend the tunable frequency range and make the resonant frequency linearly varied with the height of the metal post. The center frequency of each passband can be independently tuned with a frequency range of 0.8-3.2 GHz and tunable ratio of 4. Finally, the continuously tunable dual- and triple-band bandpass filters prototypes with second order response are designed and fabricated, of which each passband can be individually tuned with a large tuning range

    The impact of SARS on hospital performance

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    © 2008 Chu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

    An activity-based integrated land-use transport model for urban spatial distribution simulation

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    This research develops an activity-based integrated land use/transport interaction model based on the concepts – activities (mainly, households and employment activities), activity location and relocation for Chinese regions. It consists of a residential and employment location sub-model, a transport sub-model and an implicit real estate rent adjustment sub-model. The model is developed to model the urban activity distribution evolution, predict urban spatial development trends and examine various planning decision implications. It spatially distributes household and employment activity change of a study area by zone based on the current activity distribution, land use policies and the accessibilities of the zones. The model is subsequently calibrated to predict the distribution of households and employment activities in Beijing metropolitan area in 2025. Model results show that the resident and employment densities are still high in central Beijing in 2025, and most zones’ resident densities are higher than their employment densities. However, there is also significant population density increase along the 6th ring road, indicating the relocation trend of the residents and businesses to the outskirts. This is consistent with the government objectives to decentralize activities within the central urban area. The paper also suggests that the model should be used mainly in examining the possible differences arising from the adoption of different policies though predicting future of a city distribution proves feasible
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