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排序方式: 共有237条查询结果,搜索用时 15 毫秒
1.
N Sobel V Prabhakaran JE Desmond GH Glover EV Sullivan JD Gabrieli 《Canadian Metallurgical Quarterly》1997,78(1-2):115-123
A method for generating olfactory stimuli for humans within a functional magnetic resonance imaging (fMRI) experimental design is described. The system incorporates a nasal-mask in which the change from odorant to no-odorant conditions occurs in less than 500 ms and is not accompanied by visual, auditory, tactile, or thermal cues. The mask provides an ordorant-free environment following prolonged ordorant presence. Specific imaging parameters that are conducive to the study of the human olfactory system are described. In a pilot study performed using these methods, the specific patterns of activation observed converged with published experimental and clinical findings. 相似文献
2.
This paper addresses the key issue of providingflexible multimedia presentation with user participation and suggests synchronization models that can specify the user participation during the presentation. We study models like the Petrinet-based hypertext model and the object composition Petri nets (OCPN). We suggest adynamic timed Petri nets structure that can model pre-emptions and modifications to the temporal characteristics of the net. This structure can be adopted by the OCPN to facilitate modeling of multimedia synchronization characteristics with dynamic user participation. We show that the suggested enhancements for the dynamic timed Petri nets satisfy all the properties of the Petri net theory. We use the suggested enhancements to model typical scenarios in a multimedia presentation with user inputs. 相似文献
3.
Y Liu B Prabhakaran X Guo 《IEEE transactions on visualization and computer graphics》2012,18(10):1693-1703
This paper proposes an algorithm to build a set of orthogonal Point-Based Manifold Harmonic Bases (PB-MHB) for spectral analysis over point-sampled manifold surfaces. To ensure that PB-MHB are orthogonal to each other, it is necessary to have symmetrizable discrete Laplace-Beltrami Operator (LBO) over the surfaces. Existing converging discrete LBO for point clouds, as proposed by Belkin et al. [CHECK END OF SENTENCE], is not guaranteed to be symmetrizable. We build a new point-wisely discrete LBO over the point-sampled surface that is guaranteed to be symmetrizable, and prove its convergence. By solving the eigen problem related to the new operator, we define a set of orthogonal bases over the point cloud. Experiments show that the new operator is converging better than other symmetrizable discrete Laplacian operators (such as graph Laplacian) defined on point-sampled surfaces, and can provide orthogonal bases for further spectral geometric analysis and processing tasks. 相似文献
4.
5.
Significant amount of research and development is being directed on monitoring activities of daily living of senior citizens who live alone as well as those who have certain motion disorders such as Alzheimer’s and Parkinson’s. A combination of sophisticated inertial sensing, wireless communication and signal processing technologies has made such a pervasive and remote monitoring possible. Due to the nature of the sensing and communication mechanisms, these monitoring sensors are susceptible to errors and failures. In this paper, we address the issue of identifying and isolating faulty sensors in a Body Sensor Network that is used for remote monitoring of daily living activities. We identify three different types of faults in a Body Sensor Network and propose fault isolation strategies using history-based and non-history based approaches. The contributions of this paper are: (i) faulty sensor node identification in a small number of deployed body sensors (accelerometers); and (ii) identification of a faulty sensor node using a statically or dynamically bound group of sensor nodes that is sharing similar sensor signal patterns. 相似文献
6.
Kuttan Prabhakaran Jorly Joseph Nitin Madhusudan Gokhale Suresh Chandra Sharma Ramji Lal 《Journal of the American Ceramic Society》2006,89(7):2335-2337
Nanocrystalline lanthanum strontium manganite (LSM) powder has been synthesized by combustion of a transparent gel obtained by the polymerization of methylol urea and urea in a solution containing La3+ , Sr2+ , and Mn2+ (LSM ions). Chemistry of the transparent urea–formaldehyde (UF) polymer gel formation and structure of the gel have been proposed such that the LSM ions act in between the growing UF polymer chains by interacting through NH, OH, and CO groups by co-ordination and prevent polymer self-assembly through inter-chain hydrogen bonding as evidenced from infrared spectrum. Thermally stable structures formed by the decomposition of UF polymer below 300°C undergo combustion in the presence of nitrate oxidant in a temperature range from 350°–450°C. A perovskite LSM phase has been formed by self-sustained combustion of the dried gel initiated with little kerosene. The powder obtained after deagglomeration and calcination at 600°C for 2 h has a D 50 value of 0.19 μm, and the particles are aggregates of crystallites 10–25 nm in size. 相似文献
7.
Narayanan Nandakumar S.; Prabhakaran Vivek; Bunge Silvia A.; Christoff Kalina; Fine Eric M.; Gabrieli John D. E. 《Canadian Metallurgical Quarterly》2005,19(2):223
Neuroimaging studies have been inconclusive in characterizing the role of the prefrontal cortex (PFC) for maintaining increasingly larger amounts of information in working memory (WM). To address this question, the authors collected event-related functional MRI data while participants performed an item-recognition task in which the number of to-be-remembered letters was parametrically modulated. During maintenance of information in WM, the dorsolateral and the ventrolateral PFC exhibited linearly increasing activation in response to increasing WM load. Prefrontal regions could not be distinguished from one another on the basis of load sensitivity, but the dorsolateral PFC had stronger functional connectivity with the parietal and motor cortex than the ventrolateral PFC. These results suggest an increasingly important role for the PFC in actively maintaining information as the amount of that information increases. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
P. D. Hatton S. B. Wilkins T. A. W. Beale T. Johal D. Prabhakaran A. T. Boothroyd 《Journal of Superconductivity》2005,18(5-6):87-91
Soft X-ray resonant diffraction is a new technique and there exist several examples of large resonant enhancements of charge and magnetic scattering that can be obtained at the L-edges of 3d transition metal oxides. Here we have employed resonant soft X-ray scattering at the manganese L edges which provide a direct measurement of the orbital ordering. We have studied the layered manganite La0.5Sr1.5MnO4 that displays charge, spin, and orbital ordering. Energy scans at constant wavevector show that there are two separate contributions to the observed scattering, direct Goodenough orbital ordering and strong cooperative Jahn–Teller distortions of the Mn3+ ions. Finally we will show how that the charge, spin and orbital degrees of freedom are strongly correlated in these materials. 相似文献
9.
A distributed multimedia document presentation involves retrieval of objects from one or more document servers and their
presentation at the client system. The presentation of the multimedia objects has to be carried out in accordance with the
specification of temporal relationships between the objects. The retrieval of multimedia objects from the document server(s)
is influenced by factors such as temporal specification of objects presentations, throughput offered by the network service
provider, and the buffer resources on the client system. Flexibility in the temporal specification of the multimedia document
may help in deriving an object retrieval schedule that can handle variations in network throughput and buffer resource availability.
In this paper, we develop techniques for deriving a flexible object retrieval schedule for a distributed multimedia document
presentation. The schedule is based on flexible temporal specification of the multimedia document using the difference constrai
nts approach. We show how the derived retrieval schedule can be validated and modified to ensure that it can work with the
offered network throughput and the available buffer resources. 相似文献
10.