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131.
Insulin secretion rate (ISR) is not directly measurable in man but it can be reconstructed from C-peptide (CP) concentration measurements by solving an input estimation problem by deconvolution. The major difficulties posed by the estimation of ISR after a glucose stimulus, e.g., during an intravenous glucose tolerance test (IVGTT), are the ill-conditioning of the problem, the nonstationary pattern of the secretion rate, and the nonuniform/infrequent sampling schedule. In this work, a nonparametric method based on the classic Phillips-Tikhonov regularization approach is presented. The problem of nonuniform/infrequent sampling is addressed by a novel formulation of the regularization method which allows the estimation of quasi time-continuous input profiles. The input estimation problem is stated into a Bayesian context, where the a priori known nonstationary characteristics of ISR after the glucose stimulus are described by a stochastic model. Deconvolution is tackled by linear minimum variance estimation, thus allowing the derivation of new statistically based regularization criteria. Finally, a Monte-Carlo strategy is implemented to assess the uncertainty of the estimated ISR arising from CP measurement error and impulse response parameters uncertainty 相似文献
132.
Arithmetic coding for data compression 总被引:17,自引:0,他引:17
Howard P.G. Vitter J.S. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1994,82(6):857-865
Arithmetic coding provides an effective mechanism for removing redundancy in the encoding of data. We show how arithmetic coding works and describe an efficient implementation that uses table lookup as a first alternative to arithmetic operations. The reduced-precision arithmetic has a provably negligible effect on the amount of compression achieved. We can speed up the implementation further by use of parallel processing. We discuss the role of probability models and how they provide probability information to the arithmetic coder. We conclude with perspectives on the comparative advantages and disadvantages of arithmetic coding 相似文献
133.
134.
M. M. Mezdrogina A. V. Abramov G. N. Mosina I. N. Trapeznikova A. V. Patsekin 《Semiconductors》1998,32(5):555-561
The decrease in the density of dangling silicon-silicon bonds in a-Si:H films as a result of annealing in an atomic-hydrogen atmosphere is determined by their density in the initial (nonannealed)
film. The change in the total hydrogen density in a-Si:H films, annealed in an atomic-hydrogen atmosphere, is determined by the type of silicon-hydrogen bonds and the impurity
content: The hydrogen content can decrease to 1 at. % in the presence of monohydride bonds (2020 cm−1) and no change is observed in the hydrogen content in the presence of oxygen (≲0.1 at. %). A decrease in the defect density
as a result of annealing in an atomic-hydrogen atmosphere is observed for all films. The Staebler-Wronski effect — AM-1 irradiation
for 10 h — is observed for all films irrespective of the total hydrogen density, the type of silicon-hydrogen bonds, and the
presence of oxygen.
Fiz. Tekh. Poluprovodn. 32, 620–626 (May 1998) 相似文献
135.
G. F. Brand 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(7):1253-1262
The transmission of millimeter waves through a semiconductor changes according to the amount of light falling on it. In the experiments reported here, a pattern of light and shadow is projected onto a sheet of semiconductor and the regions of greater and lesser transmission serve as a diffracting object for a millimeter-wave beam. The light source is a quartz tungsten halogen lamp. A lock-in amplifier is employed to overcome difficulties due to the differences in transmitted power being small. 相似文献
136.
137.
138.
Silver nitrate-acetonitrile and π iodine-benzene complexes in thermotropic liquid crystals have been studied by 1H, 2H, and 13C NMR spectroscopy and by optical microscopy. Evidence for at least two silver complexes in each liquid crystal is presented. 相似文献
139.
W. Fallmann P. Hudek I. Kostic A. Neubauer D. Pum I. Rangelow K. Riedling F. Rüdenauer U. B. Sleytr G. Stangl 《e & i Elektrotechnik und Informationstechnik》1998,115(7-8):349-353
This contribution describes the preparation, based upon a chemically amplified novolak resist (CAR), electron beam lithography, and ECR plasma etching, of structures with a high aspect ratio (10∶1) and lateral dimensions in the sub-micrometer range (150nm–300nm) which may serve as collector surfaces for sub-μm dust particles in a space experiment. 相似文献
140.
Bouferrache B. Krim G. Mejdoub N. Quanjer P.H. Freville M. Libert J.P. 《IEEE transactions on bio-medical engineering》1998,45(11):1305-1312
Dynamic modeling of lung C18O diffusion is used to measure the C18O transfer factor (TLco) of 14 newborns aged 1-4 mo. The model equation is based on the alveolar fractions of C18O and on changing alveolar ventilation induced by the rebreathing conditions. The model does not involve the volume of the rebreathing bag which is usually needed when applying rebreathing technique add which is a source of error. The equation is discretized and solved for recorded data obtained with equipment adapted to use in newborns. A least-square parameter calculation technique is applied to estimate TLco. Results show a strong relationship between this index and the biometrical ones and confirm those found in the literature featuring that the measurement duration can be considerably shortened 相似文献