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Pattern Generation (pattern + generation)
Selected AbstractsMulticolor Pattern Generation in Photonic Bandgap Composites,ADVANCED MATERIALS, Issue 2 2005P. Jiang The generation of complex, permanent, multicolor patterns in photonic bandgap films is demonstrated. The procedure allows for the overall spatial control of the reflected color on the surface of a photonic crystal, as well as the ability to define the visible or near-IR response of a patterned region through control of the stop-band wavelength. For example, the attached image presents a 10,mm wide, orange, "tiger paw" insignia templated on a green background. See also inside front cover. [source] ZnO nanowire arrays , Pattern generation, growth and applicationsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2010Margit Zacharias Abstract ZnO nanowires and related materials are in the focus of attention for electronic, optical or sensor applications. However, size, position and arrangement control are essential conditions for the development of future nanowire based devices. Various kinds of template methods including nanosphere lithography and UV laser interference lithography are powerful tools for the preparation of the starting metal catalyst arrays and will be demonstrated and discussed. However, only if the growth mechanism and its guiding parameters are understood in detail, the template will force a pattern arranged growth of nanowires. The paper gives an overview of the various kinds of growth modes for vertical arranged nanowires. Specific experimental conditions establishing the VS or the VLS growth are discussed. In addition, insight is given why the patterning is not all the time conserved and how to overcome these obstacles. In the second part different kinds of applications are summarized. Electronic properties are discussed based on metal,semiconductor,metal devices. The influence of a core,shell nanowire structure on the optical properties is demonstrated. In addition, a simple approach for ZnO nanowire based gas sensors is discussed and shown. As a last example, the transfer of Al2O3 coated nanowires into spinel tubes is reported. [source] FlattGen: Teaching tool for surface flatteningCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 2 2006Simon Kolmani Abstract In many cases in the industry, we can face a problem, where an object has to be manufactured out of thin plane material. This is especially the case in the car, airplane, shipbuilding, textile, and shoe making industry. In order to manufacture such an object, a pattern has to be generated first. It has to be cut out from plane material and then bend to the final shape. The same problem can be found also in computer graphics, where flat patterns are used to decrease distortions in texture mapping. Therefore, it is important for designers and computer engineers to master the flat pattern generation. In literature, a great number of methods for pattern generation can be found and it is important to know their advantages and weaknesses. In this article, the application FlattGen is presented where the most important flattening methods can be seen and compared to each other. In this way, students can experiment and prepare themselves better for the future work. © 2006 Wiley Periodicals, Inc. Comput Appl Eng Educ 14: 106,119, 2006; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20060 [source] Semantic patterns for user-interactive question answeringCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 7 2008Tianyong Hao Abstract A new type of semantic pattern is proposed in this paper, which can be used by users to post questions and answers in user-interactive question answering (QA) systems. The necessary procedures of using semantic patterns in a QA system are also presented, which include question structure analysis, pattern matching, pattern generation, pattern classification and answer extraction. Both the manual creation method and the automatic generation method are proposed for patterns for different applications. A pattern instantiation level metrics is also presented for the predication of the quality of generated or learned patterns. We implemented a user interface for using the semantic pattern in our QA system, which allows users to effectively post and answer questions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Homeostatic plasticity induced by chronic block of AMPA/kainate receptors modulates the generation of rhythmic bursting in rat spinal cord organotypic culturesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2001Micaela Galante Abstract Generation of spontaneous rhythmic activity is a distinct feature of developing spinal networks. We report that rat embryo organotypic spinal cultures contain the basic circuits responsible for pattern generation. In this preparation rhythmic activity can be recorded from ventral interneurons and is developmentally regulated. When chronically grown in the presence of an AMPA/kainate receptor blocker, this circuit expresses long-term plasticity consisting largely of increased frequency of fast synaptic activity and reduction in slow GABAergic events. We examined whether, once this form of homeostatic plasticity is established, the network could still exhibit rhythmicity with properties similar to controls. Control or chronically treated ventral interneurons spontaneously generated (with similar probability) irregular, network-driven bursts over a background of ongoing synaptic activity. In control cultures increasing network excitability by strychnine plus bicuculline, or by raising [K+]o, induced rapid-onset, regular rhythmic bursts. In treated cultures the same pharmacological block of Cl, -mediated transmission or high-K+ application also induced regular patterned activity, although significantly faster and, in the case of high K+, characterized by slow onset due to postsynaptic current summation. Enhancing GABAergic transmission by pentobarbital surprisingly accelerated the high-K+ rhythm of control cells (though depressing background activity), whereas it slowed it down in chronically treated cells. This contrasting effect of pentobarbital suggests that, to preserve bursting ability, chronic slices developed a distinct GABAergic inhibitory control on over-expressed bursting circuits. Conversely, in control slices GABAergic transmission depressed spontaneous activity but it facilitated bursting frequency. Thus, even after homeostatic rearrangement, developing mammalian spinal networks still generate rhythmic activity. [source] Cephalopod chromatophores: neurobiology and natural historyBIOLOGICAL REVIEWS, Issue 4 2001J. B. MESSENGER ABSTRACT The chromatophores of cephalopods differ fundamentally from those of other animals: they are neuromuscular organs rather than cells and are not controlled hormonally. They constitute a unique motor system that operates upon the environment without applying any force to it. Each chromatophore organ comprises an elastic sacculus containing pigment, to which is attached a set of obliquely striated radial muscles, each with its nerves and glia. When excited the muscles contract, expanding the chromatophore; when they relax, energy stored in the elastic sacculus retracts it. The physiology and pharmacology of the chromatophore nerves and muscles of loliginid squids are discussed in detail. Attention is drawn to the multiple innervation of dorsal mantle chromatophores, of crucial importance in pattern generation. The size and density of the chromatophores varies according to habit and lifestyle. Differently coloured chromatophores are distributed precisely with respect to each other, and to reflecting structures beneath them. Some of the rules for establishing this exact arrangement have been elucidated by ontogenetic studies. The chromatophores are not innervated uniformly: specific nerve fibres innervate groups of chromatophores within the fixed, morphological array, producing ,physiological units' expressed as visible ,chromatomotor fields'. The chromatophores are controlled by a set of lobes in the brain organized hierarchically. At the highest level, the optic lobes, acting largely on visual information, select specific motor programmes (i.e. body patterns); at the lowest level, motoneurons in the chromatophore lobes execute the programmes, their activity or inactivity producing the patterning seen in the skin. In Octopus vulgaris there are over half a million neurons in the chromatophore lobes, and receptors for all the classical neurotransmitters are present, different transmitters being used to activate (or inhibit) the different colour classes of chromatophore motoneurons. A detailed understanding of the way in which the brain controls body patterning still eludes us: the entire system apparently operates without feedback, visual or proprioceptive. The gross appearance of a cephalopod is termed its body pattern. This comprises a number of components, made up of several units, which in turn contains many elements: the chromatophores themselves and also reflecting cells and skin muscles. Neural control of the chromatophores enables a cephalopod to change its appearance almost instantaneously, a key feature in some escape behaviours and during agonistic signalling. Equally important, it also enables them to generate the discrete patterns so essential for camouflage or for signalling. The primary function of the chromatophores is camouflage. They are used to match the brightness of the background and to produce components that help the animal achieve general resemblance to the substrate or break up the body's outline. Because the chromatophores are neurally controlled an individual can, at any moment, select and exhibit one particular body pattern out of many. Such rapid neural polymorphism (,polyphenism') may hinder search-image formation by predators. Another function of the chromatophores is communication. Intraspecific signalling is well documented in several inshore species, and interspecific signalling, using ancient, highly conserved patterns, is also widespread. Neurally controlled chromatophores lend themselves supremely well to communication, allowing rapid, finely graded and bilateral signalling. [source] Pattern Formation And Rhythm Generation In The Ventral Respiratory GroupCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2000Donald R McCrimmon SUMMARY 1. There is increasing evidence that the kernel of the rhythm-generating circuitry for breathing is located within a discrete subregion of a column of respiratory neurons within the ventrolateral medulla referred to as the ventral respiratory group (VRG). It is less clear how this rhythm is transformed into the precise patterns appearing on the varied motor outflows. 2. Two different approaches were used to test whether subregions of the VRG have distinct roles in rhythm or pattern generation. In one, clusters of VRG neurons were activated or inactivated by pressure injection of small volumes of neuroactive agents to activate or inactivate groups of respiratory neurons and the resulting effects on respiratory rhythm and pattern were determined. The underlying assumption was that if rhythm and pattern are generated by neurons in different VRG subregions, then we should be able to identify regions where activation of neurons predominantly alters rhythm with little effect on pattern and other regions where pattern is altered with little effect on rhythm. 3. Based on the pattern of phrenic nerve responses to injection of an excitatory amino acid (DL -homocysteate), the VRG was divided into four subdivisions arranged along the rostrocaudal axis. Injections into the three rostral regions elicited changes in both respiratory rhythm and pattern. From rostral to caudal the regions included: (i) a rostral bradypnoea region, roughly associated with the Bötzinger complex; (ii) a dysrhythmia/tachypnoea area, roughly associated with the pre-Bötzinger complex (PBC); (iii) a second caudal bradypnoea area; and, most caudally, (iv) a region from which no detectable change in respiratory motor output was elicited. 4. In a second approach, the effect of unilateral lesions of one subregion, the PBC, on the Breuer,Hering reflex changes in rhythm were determined. Activation of this reflex by lung inflation shortens inspiration and lengthens expiration (TE). 5. Unilateral lesions in the PBC attenuated the reflex lengthening of TE, but did not change baseline respiratory rhythm. 6. These findings are consistent with the concept that the VRG is not functionally homogeneous, but consists of rostrocaudally arranged subregions. Neurons within the so-called PBC appear to have a dominant role in rhythm generation. Nevertheless, neurons within other subregions contribute to both rhythm and pattern generation. Thus, at least at an anatomical level resolvable by pressure injection, there appears to be a significant overlap in the circuitry generating respiratory rhythm and pattern. [source] | ||||||||||