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排序方式: 共有624条查询结果,搜索用时 78 毫秒
621.
Joaquin T. Valderrama Angel de la Torre Isaac Alvarez Jose Carlos Segura A. Roger. D. Thornton Manuel Sainz Jose Luis Vargas 《Computer methods and programs in biomedicine》2014
The recording of the auditory brainstem response (ABR) is used worldwide for hearing screening purposes. In this process, a precise estimation of the most relevant components is essential for an accurate interpretation of these signals. This evaluation is usually carried out subjectively by an audiologist. However, the use of automatic methods for this purpose is being encouraged nowadays in order to reduce human evaluation biases and ensure uniformity among test conditions, patients, and screening personnel. This article describes a new method that performs automatic quality assessment and identification of the peaks, the fitted parametric peaks (FPP). This method is based on the use of synthesized peaks that are adjusted to the ABR response. The FPP is validated, on one hand, by an analysis of amplitudes and latencies measured manually by an audiologist and automatically by the FPP method in ABR signals recorded at different stimulation rates; and on the other hand, contrasting the performance of the FPP method with the automatic evaluation techniques based on the correlation coefficient, FSP, and cross correlation with a predefined template waveform by comparing the automatic evaluations of the quality of these methods with subjective evaluations provided by five experienced evaluators on a set of ABR signals of different quality. The results of this study suggest (a) that the FPP method can be used to provide an accurate parameterization of the peaks in terms of amplitude, latency, and width, and (b) that the FPP remains as the method that best approaches the averaged subjective quality evaluation, as well as provides the best results in terms of sensitivity and specificity in ABR signals validation. The significance of these findings and the clinical value of the FPP method are highlighted on this paper. 相似文献
622.
G. Dattoli C. Mari A. Torre C. Chiccoli S. Lorenzutta G. Maino 《Journal of scientific computing》1992,7(2):175-196
Recently, some multivariable special functions have been obtained by generalizing functions of Bessel type. Here, we continue the treatment of these functions starting fromJ
n
(x, y; i), which is of noticeable practical interest. Finally, we consider the cases of functionsJ
n(x1, x2,..., xM) and the related modified version,I
n(x1, x2,..., xM), with two significant physical applications. Calculations of multivariable generalized Bessel functions are discussed and numerical results are given forJ
n(x1,x2;i), withn=0, 1, in a region of interest. 相似文献
623.
Tasha Yuliandra Konstantina Touvleliou Xavier de la Torre Francesco Botrè Steffen Loke Eduard Isenmann Sarah Valder Patrick Diel Maria Kristina Parr 《Molecular nutrition & food research》2023,67(14):2200518
Scope
The phytosteroid ecdysterone is present in spinach. In this study, the urinary elimination of ecdysterone and its metabolites in humans is investigated following spinach consumption of two different culinary preparations.Methods and results
Eight participants (four males, four females) ingested 950 (27.1) g sautéed spinach (average [±standard deviation (SD)]) and 912 (70.6) g spinach smoothie as second intervention after washout. Post-administration urines are analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). After intake of both preparations, ecdysterone and two metabolites, 14-deoxy-ecdysterone, and 14-deoxy-poststerone, are excreted in urine. The maximum concentration of ecdysterone is ranging from 0.09 to 0.41 µg mL−1 after sautéed spinach and 0.08–0.74 µg mL−1 after smoothie ingestion. The total excreted amount (mean% [±SD]) in the urine as a parent drug plus the metabolites is only 1.4 (1.0) for both sautéed spinach and smoothie. The apparent sex related differences in 14-deoxy-poststerone excretion will need further investigations.Conclusion
Only a small proportion of ecdysterone from spinach is excreted into urine. No significant differences are found in concentration and recovered amount (%) of ecdysterone, 14-deoxy-ecdysterone, and 14-deoxy-poststerone in urine between sautéed spinach and smoothie ingestion. A discrimination between ecdysterone from food or preparations will be challenging based on urinary concentrations only, at least for later post-administration samples. 相似文献624.
J. Biagiotti S. Fiori L. Torre M. A. López-Manchado J. M. Kenny 《Polymer Composites》2004,25(1):26-36
This work presents a systematic and statistical approach to evaluate and predict the properties of random discontinuous natural fiber reinforced composites. Different composites based on polypropylene and reinforced with natural fibers were produced and their mechanical properties are measured together with the distribution of the fiber size and the fiber diameter. The values obtained were related to the theoretical predictions, using a combination of the Griffith theory for the effective properties of the natural fibers and the Halpin-Tsai equation for the elastic modulus of the composites. The relationships between experimental results and theoretical predictions were statistically analyzed using a probability density function estimation approach based on neural networks. The results show a more accurate expected value with respect to the traditional statistical function estimation approach. In order to point out the particular features of natural fibers, the same proposed method is also applied to PP–glass fiber composites. 相似文献