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Forty-three patients with spastic quadriplegia (mean age 7.9 years, range 3.3 to 17.2 years) underwent bone mineral density (BMD) measurement of the lumbar spine and were evaluated between 2.6 and 5.5 years (mean 3.8) later to determine whether this measurement had predicted risk of fracture over the subsequent period of observation. Other potential risk factors that were evaluated include body weight z score, serum vitamin D levels, previous fracture, and hip spica casting. The baseline measurements showed that BMD falls further below normal with increasing age and was more than one standard deviation below age-matched normal mean in 38 of the 43 patients. Fracture rate did not differ between those with low and those with very low spinal BMD. Similarly, serum vitamin D levels and body weight z scores were not predictive of fracture. However, fracture rate was over fourfold greater following spica casting and more than threefold greater following an initial fracture. Fracture rates in the study group were similar to those reported for age- and sex-matched normal children, though generally the location of the fractures and mechanisms of injury differed. 相似文献
13.
Smart cars, smart highways 总被引:2,自引:0,他引:2
Advanced electronics is being used to unclog the transportation network and allow private vehicles, trucks, buses and trains to move further faster. already a range of technologies and ideas have been explored, deployed, and tested as part of the Intelligent Vehicle Highway System programs in the United States and Japan, and in the Road Transport Informatics program in Europe. The authors describe how these latest electronics for automobiles and roadways herald far fewer traffic jams, greater safety, and perhaps even a decline in pollution 相似文献
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P Verkade LH Schrama AJ Verkleij WH Gispen AB Oestreicher 《Canadian Metallurgical Quarterly》1997,79(4):1207-1218
Calmodulin and de-phosphorylated B-50/growth-associated protein-43 (GAP-43) have been shown to bind in vitro in a molecular complex, but evidence for an in situ association in the nervous system does not exist. Previously, we have reported that, in the model of the regenerating rat sciatic nerve, the B-50/GAP-43 immunoreactivity is increased and concentrated at the axolemma of unmyelinated axons located proximal to the site of injury and axon outgrowth. To explore a putative function of B-50/GAP-43, namely, the capacity of binding calmodulin to the plasma membrane, we examined the ultrastructural distribution of calmodulin in the proximal unmyelinated axon shafts of this model, using double immunolabelling and detection by fluorescent or gold probes conjugated to second antibodies. Immunofluorescence showed that seven days post-sciatic nerve crush the calmodulin immunoreactivity, similar to B-50/GAP-43 immunoreactivity, was intense in unmyelinated axon shafts located proximal to the site of injury of the regenerating nerve. Ultrastructurally, calmodulin was located at the axolemma of these regenerating unmyelinated axon shafts and inside the axoplasm, where it was associated with vesicles and microtubules. The plasma membrane labelling (approximately 69%) was significantly higher than the axoplasmic labelling. Over 60% of the plasma membrane-associated calmodulin co-localized with B-50/GAP-43 in a non-random distribution. Since normally calmodulin is largely present in the cytoplasm, these data suggest that calmodulin has been concentrated at the plasma membrane of unmyelinated axons, most probably by B-50/GAP-43. If the concentrating effect is due to B-50/GAP-43, then there is a possibility that these proteins may be present as a molecular complex in situ. The physiological significance could be that this association regulates the local availability of both B-50/GAP-43 and calmodulin for other interactions. 相似文献
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Rats bled to a severe condition of volume-controlled hemorrhagic shock were randomly assigned to one of the following treatments: (1) saline, 1 ml/kg i.v.; (2) saline, 0.2 ml/kg per min i.v. for 10 min; (3) ACTH-(1-24), 160 micrograms/kg i.v.; 4) methylprednisolone, 40 mg/kg i.v.; (5) methylprednisolone, 80 mg/kg i.v.; (6) aprotinin, 10,000 KIU/kg i.v.; (7) norepinephrine, 5 micrograms/kg per min i.v. for 10 min; (8) norepinephrine, 10 micrograms/kg per min i.v. for 10 min. All rats treated with saline or with either of the two doses of methylprednisolone, and half of the rats treated with aprotinin, died within the subsequent 2 h. On the other hand, rats treated with norepinephrine, at either dose, or with ACTH-(1-24) were all still alive 2 h later, a similar improvement in cardiovascular and respiratory parameters being obtained with the two treatments. The effect of ACTH on mean arterial pressure was however more sustained throughout the observation period. These results further support the potential usefulness of ACTH-(1-24) as first-aid treatment in cases of severe blood losses. 相似文献
17.
A mild thermal treatment of wood leads to improved macroscopic properties (dimensional stabilization and resistance against fungal degradation). The chemical modifications induced by the thermal treatment were investigated by means of DRIFT spectroscopy on wood blocks in order to explain the new macroscopic properties on a molecular level. The formation of new ether linkage was observed in addition to the well-known acidic hydrolysis reactions of wood. Fungal attack was found to take place even after thermal degradation of pentosanes by a standard oxidative way. A competition between depolymerization and condensation reactions was observed. 相似文献
18.
Hybrid finite-element method for discretising cylindrically symmetric parts in electrotechnical models 总被引:1,自引:0,他引:1
In many technical devices such as transformers and electrical machines, large differences in geometric dimensions are observed. As a consequence, the generation of a 3D computational grid for the whole device leads to unacceptably large numbers of elements or can even fail. In addition to the commonly applied cartesian or cylindrical symmetries of the overall geometry, the model can be subdivided into parts featuring translational or cylindrical symmetries. Such parts are discretised separately, accounting for the local symmetry, and are then combined with the surrounding 3D model. Excitations and boundary conditions of the submodels are not necessarily symmetric but are expected to be smooth in the direction of the symmetry. Then, the field distribution at the interface is well approximated by a set of spectral elements along the dimension of symmetry. Coupling between the model parts is carried out by means of Lagrange multipliers. A single-phase transformer with thin insulation sheets is taken as an example to illustrate the proposed hybrid discretisation. The cross-section of the cylindrically symmetric part containing thin sheets, is represented by a fine 2D finite-element mesh so that all the geometrical details can be resolved, and the rest of the structure is discretised by a 3D mesh. Nevertheless, a fully 3D field distribution is calculated in all model parts. Only a small number of harmonic functions is needed to account for the azimuthal field variation at the cylindrical interface. Hence, the number of unknowns in the numerical model is reduced significantly, while a high level of accuracy is maintained 相似文献
19.
We evaluated the effect of the image acquisition parameters on the accuracy of the principal axes and surface-fitting techniques for three-dimensional image registration. Using two types of phantom objects, MR brain image and a mathematically defined ellipsoid, we simulated pairs of scans with known acquisition parameters, including longitudinal coverage, magnitude of mis-registration, number of sections and section thickness. Both methods are sensitive to the systematic deformation of contours. The principal axes method is also sensitive to incomplete scan coverage and to the x-axis and y-axis misangulation. Both methods are insensitive to the number of sections, section thickness and the number of points per section. Surface fitting performed well without user supervision. There is no need for routine inclusion of the scaling factors as search parameters. The results confirm the feasibility of three-dimensional multimodality registration of brain scans with accuracy 1-2 mm, with surface fitting being the method of choice. 相似文献
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