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1.
A bioengineered spinal cord is fabricated via extrusion‐based multimaterial 3D bioprinting, in which clusters of induced pluripotent stem cell (iPSC)‐derived spinal neuronal progenitor cells (sNPCs) and oligodendrocyte progenitor cells (OPCs) are placed in precise positions within 3D printed biocompatible scaffolds during assembly. The location of a cluster of cells, of a single type or multiple types, is controlled using a point‐dispensing printing method with a 200 µm center‐to‐center spacing within 150 µm wide channels. The bioprinted sNPCs differentiate and extend axons throughout microscale scaffold channels, and the activity of these neuronal networks is confirmed by physiological spontaneous calcium flux studies. Successful bioprinting of OPCs in combination with sNPCs demonstrates a multicellular neural tissue engineering approach, where the ability to direct the patterning and combination of transplanted neuronal and glial cells can be beneficial in rebuilding functional axonal connections across areas of central nervous system (CNS) tissue damage. This platform can be used to prepare novel biomimetic, hydrogel‐based scaffolds modeling complex CNS tissue architecture in vitro and harnessed to develop new clinical approaches to treat neurological diseases, including spinal cord injury.  相似文献   
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The total population and the overall average density are derived for a single city, in which the spatial structure conforms approximately to the negative exponential function. It is then shown that across the cities of an urban system, the areal extent of a city is positively related to its average density and also to its population. Consideration is next given to a system of regions and again to the manner in which areal extent is related to average density and population across regions. In this setting, however, the relationships are usually different from those found within an urban system.  相似文献   
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Autonomous Unmanned Aerial Vehicles (UAVs) have the potential to significantly improve current working practices for a variety of applications including aerial surveillance and search-and-rescue. However before UAVs can be widely integrated into civilian airspace there are a number of technical challenges which must be overcome including provision of an autonomous method of landing which would be executed in the event of an emergency. A fundamental component of autonomous landing is safe landing zone detection of which terrain classification is a major constituent. Presented in this paper is an extension of the Multi-Modal Expectation Maximization algorithm which combines data in the form of multiple images of the same scene, with knowledge in the form of historic training data and Ordnance Survey map information to compute updated class parameters. These updated parameters are subsequently used to classify the terrain of an area based on the pixel data contained within the images. An image''s contribution to the classification of an area is then apportioned according to its coverage of that area. Preliminary results are presented based on aerial imagery of the Antrim Plateau region in Northern Ireland which indicates potential in the approach used.  相似文献   
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A methodology for using a calibrated filter radiometer to measure and monitor the spectral radiance of calibration sources is described. An example is presented using the NIST calibration sphere source that is used to support the NASA Earth Observing remote-sensing program.  相似文献   
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The aim of the present study was to investigate the concept of complexity in wine as a function of domain-specific expertise. Thirty-nine wine professionals and 30 wine consumers participated in interviews aimed at inducing verbal responses concerning their representations of (i) wine complexity in general, (ii) wine complexity in relation to white wine with perceived ageing ability, and (iii) wine complexity in relation to red wine with perceived ageing ability. The verbal data were analysed with the textual data analysis software ALCESTE ( [Reinert, 1983], [Reinert, 1986], [Reinert, 2001] and [Reinert, 2008]). Results showed that wine professionals as a group tended to represent complexity in wine in terms of extrinsic factors such as oenological processes (e.g., lees stirring; use of oak) and terroir variables (e.g., soil; viticulture: see Moran, 2006). On the other hand, wine consumers’ representations of wine complexity were dominated by intrinsic factors relating to their experience of consuming wine (e.g., smell and taste of wines) and were personalised and subjective (e.g., about their own enjoyment and pleasure). Further, wine professionals’ representations clearly differentiated between characteristics of white wine with ageing potential and characteristics of red wine with ageing potential whereas those of wine consumers did not. The results are discussed in terms of the salient components of the concept of complexity in wine, including wine judged to have ageing ability, along with the cognitive processing associated with wine expertise.  相似文献   
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The combination of a cryogenic radiometer and synchrotron radiation enables detector scale realization in spectral regions that are otherwise difficult to access. Cryogenic radiometry is the most accurate primary detector-based standard available to date, and synchrotron radiation gives a unique broadband and continuous spectrum that extends from x ray to far IR. We describe a new cryogenic radiometer-based UV radiometry facility at the Synchrotron Ultraviolet Radiation Facility II at the National Institute of Standards and Technology. The facility is designed to perform a variety of detector and optical materials characterizations. The facility combines a high-throughput, normal incidence monochromator with an absolute cryogenic radiometer optimized for UV measurements to provide absolute radiometric measurements in the spectral range from 125 nm to approximately 320 nm. We discuss results on photodetector characterizations, including absolute spectroradiometric calibration, spatial responsivity mapping, spectroreflectance, and internal quantum efficiency. In addition, such characterizations are used to study UV radiation damage in photodetectors that can shed light on the mechanism of the damage process. Examples are also given for UV optical materials characterization.  相似文献   
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