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31.
The change of foot length and width with age has been reported in a few anthropometric studies in the literature. However, the relationship with body height rarely is reported, and the dynamic effect of weightbearing on foot size has not been documented. In this series, 2829 children 3 to 18 years of age of equal gender distribution were included in the study. The foot length and width on weightbearing and nonweightbearing were measured with a special precision electronic caliper. The foot length and width were found to increase linearly from the age of 3 years until 12 years in girls and 15 years in boys. This was followed by a phase during which the increase plateaued. The foot length and width increased significantly on weightbearing at all ages in both genders with a mean of 2.1 to 4.4 mm or 3.1% to 4.8%, respectively. The foot length and width also were found to correlate significantly with the body height in both genders, with a correlation coefficient of 0.96 to 0.98. No significant differences were found between the sizes of the dominant and nondominant foot in either gender. 相似文献
32.
OFDM/FM frame synchronization for mobile radio data communication 总被引:13,自引:0,他引:13
A synchronization scheme enabling the use of orthogonal frequency division multiplexing (OFDM)/FM over a mobile radio channel in a pure ALOHA environment is proposed. The scheme encodes synchronization information in parallel with data in the same manner in which data is encoded in the OFDM/FM frame. The synchronization information is in the form of tones, centered in certain reserved frequency subchannels of the OFDM signal. The receiver uses a correlation detector, implemented in the frequency domain, to acquire synchronization accurately on a packet-by-packet basis. Experimental results indicate that the bit-error-rate performance achievable with the proposed scheme is within 1.5 dB of the performance obtained with ideal synchronization 相似文献
33.
Occlusion of large atrial septal defects with a centering buttoned device: early clinical experience
EB Sideris M Leung JH Yoon CR Chen R Lochan AM Worms C Rey B Meier 《Canadian Metallurgical Quarterly》1996,131(2):356-359
A feasibility clinical study was conducted for the transcatheter occlusion of large ostium secundum atrial septal defects with the centering buttoned device. The centering buttoned device is a modification of the regular buttoned device in which a centering counter-occluder is sutured at the central 40% portion of the occluder. During centering it is stretched, forming a parachute-shaped structure and pulling the occluder over the center of the defect. During buttoning, the counter-occluder forms a double figure eight, opposing the right atrial side of the atrial septum. Occlusion was performed in 12 patients aged 6 to 56 years. All had been rejected for transcatheter occlusion by the regular buttoned device, because of either their defect size or the lack of adequate septal rim. The defect size varied between 23 and 31 mm, and the device size varied between 45 and 60 mm. Nine had immediate effective occlusions of their defects and three residual shunts. One patient with unbuttoning had hemolysis at 2 weeks and underwent surgery. Early results of the transcatheter occlusion of large atrial septal defects are promising, and larger clinical trials are justified. 相似文献
34.
BACKGROUND: Pancreatic cancer is a common cause of mortality in the United States, with an estimated 27,800 people dying of the disease in this country in 1996. Epidemiologic studies have suggested that Western diets containing high fat, high protein, and low calcium contents are associated with increased incidence of pancreatic cancer. PURPOSE: We investigated whether a Western-style diet containing increased fat content and decreased calcium and vitamin D contents would induce epithelial cell hyperproliferation (excess cell duplication) or hyperplasia (excess cell accumulation) in the pancreas, as was previously demonstrated in the colon and mammary gland. METHODS: C57BL/6J mice at 4 weeks of age were randomly assigned to one of two groups of 14 mice each. One group received the control diet ad libitum, and the other group was given the Western-style diet ad libitum. After 6, 9, and 15 weeks on the diet, four or five mice per group were infused with 5-bromo-2'-deoxyuridine (BrdU) for 72 hours by use of subcutaneously implanted Alzet osmotic pumps. The mice were then killed, and the pancreas of each mouse was removed. In the exocrine pancreas with ductal secretion, the duct system (including interlobular and intralobular ducts and centroacinar [i.e., centroductular] cells) and acini were measured both histopathologically and immunohistochemically (BrdU) and were analyzed without knowledge of the source of the specimens. Two-way analysis of variance was carried out. All P values were generated from two-sided tests for statistical significance. RESULTS: The number of pancreatic ducts (interlobular, intralobular, and centro-acinar-cancer-prone regions in certain rodent models and in humans) and acini per mouse in the Western-style diet group was similar to that in the control diet group during the entire feeding period (P = .76, .32, .93, and .42, respectively). Statistically significant higher BrdU-labeling indices of the ductal interlobular and intralobular epithelial cells were seen in mice fed the Western-style diet than in mice fed the control diet during the entire observation period (P = .014 and .016, respectively). There was no statistically significant difference (P = .098) between both diet groups in the BrdU-labeling indices of the centroacinar epithelial cells. CONCLUSIONS: A Western-style diet induced pancreatic epithelial cell hyperproliferation in mice, further suggesting that increased fat content and decreased calcium and vitamin D contribute to the development of pancreatic neoplasms. 相似文献
35.
The GM2 activator protein is a small monomeric protein containing a single site for Asn-linked glycosylation. Its only proven in vivo function is to act as a substrate specific cofactor for the hydrolysis of GM2 ganglioside by lysosomal beta-hexosaminidase A. However, we and others have shown it can act as a general glycolipid transporter at neutral pH in vitro. Any other possible in vivo functions would require that some of the newly synthesized activator molecules not be targeted to the lysosome. The lysosomal targeting mechanism for the activator has not been conclusively identified. While earlier reports suggested that it is likely through the mannose-6-phosphate receptor, another more recent report demonstrated that deficient human cells could recapture nonglycosylated, bacterially produced activator, suggesting its use of an alternate targeting pathway. Here, we demonstrate that the mannose-6-phosphate pathway is likely the major intracellular, biosynthetic route to the lysosome, as well as a high affinity recapture pathway for the endocytosis of activator protein from extracellular fluids. Additionally, we show that there exists a second lower affinity recapture pathway that requires its native protein structure, is carbohydrate independent, and likely does not involve its ability to bind glycosphingolipids in the plasma membrane. Finally, we document that the pool of newly synthesized precursor activator protein contains a majority of molecules with a complex-type oligosaccharide, which cannot contain a functional mannose-6-phosphate targeting signal. These molecules makeup the secreted forms of the protein in normal human fibroblasts. 相似文献
36.
The complex backpropagation algorithm 总被引:6,自引:0,他引:6
The backpropagation (BP) algorithm that provides a popular method for the design of a multilayer neural network to include complex coefficients and complex signals so that it can be applied to general radar signal processing and communications problems. It is shown that the network can classify complex signals. The generalization of the BP to deal with complex signals should make it possible to expand the line of applications of this powerful nonlinear signal processing algorithm 相似文献
37.
The development of biaxial segmental orientation and stress in a flexible-chain polymer fluid subjected to steady biaxial extensional flow is analyzed. Closed-formula model based on the Padè approximation of the inverse Langevin function in the non-Gaussian distribution of the chain end-to-end vectors is considered. The approach is free from the limitations related to finite chain extensibility and slow convergence of the series expansion formulations at higher chain deformations.Segmental orientation is characterized by the average orientation tensor, related axial orientation factors and global orientation anisotropy. Orientational behavior and corresponding stresses in the biaxial elongational potential flow are discussed in a wide range of elongation rates. Orientation characteristics calculated for the biaxial flow deformation are much higher than those predicted for the affine biaxial stretch deformation in polymer solids. 相似文献
38.
This paper presents an analysis of a monopole in free space. The result is given in a concise form that facilitates numerical programming. Moreover, the calculation involves no numerical integration and, thus, the computation is extremely fast 相似文献
39.
40.
Abstract: Non-classical fractals generated by many generators are of interest. Random fractals caused by the random action of given generators and by random generrrtors are discussed The generators may have different scales. The fractal spectral function, the generalized fractal dimensions and scaling index are derived explicitly. Examples include the cracking patterns of concrete mix. 相似文献