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排序方式: 共有268条查询结果,搜索用时 812 毫秒
61.
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A new mode of operation of pMOS radiation dosimeters is explored, using zero applied oxide field. Over a certain dose range, a linear dependence of response against dose was found. Charge pumping currents and threshold voltages were measured as a function of dose. 相似文献
63.
JR Vaughan MJ Farrer ZK Wszolek T Gasser A Durr Y Agid V Bonifati G DeMichele G Volpe S Lincoln M Breteler G Meco A Brice CD Marsden J Hardy NW Wood 《Canadian Metallurgical Quarterly》1998,7(4):751-753
PURPOSE: Tumor hypoxia may be an important factor predicting relapse following radiation therapy. This study was designed to determine the relationship between the oxygenation parameters measured using a polarographic oxygen electrode, prior to and during treatment in patients with cervix cancer, and to assess these results with regard to patient survival. MATERIALS AND METHODS: Forty-three patients had pretreatment oxygen assays performed and measurements repeated following external beam radiation to a median dose of 50 Gy (range 26-52 Gy). Stage distribution showed 15 patients in Stage IB, 17 in Stage II, and 11 in Stage III. The median tumor size was 5 cm (range 3-10 cm). RESULTS: The median proportion of pO2 values <5 mm Hg (the HP5) was 41% following radiation, and the median pO2 was 12 mm Hg. These results were not significantly different from the pretreatment HP5 or pO2 of 37% and 12 mm Hg, respectively. Disease-free survival at 2 years was 50% in patients with posttreatment HP5 < or =50%, compared to 60% when posttreatment HP5 was >50% (p = 0.35). CONCLUSIONS: Unlike pretreatment results, tumour oxygenation measured following external radiation does not appear to be a useful predictive assay in patients with cervical cancer. 相似文献
64.
This paper is concerned with the relation between the dynamics of a given Hamiltonian system with a given symmetry group and its reduced dynamics. We illustrate the process of visualization of reduced orbits using the double spherical pendulum. In this process of visualization, one sees certain patterns when the dynamics is viewed relative to rotating frames with certain critical angular velocities. By using the reduced dynamics, we also explain these patterns. We show that if the motion on the phase space reduced by a continuous symmetry group at a given momentum level is periodic, then there is a uniformly rotating frame, that is, a one-parameter group motion, relative to which the unreduced trajectory is periodic with the same period. If the continuous symmetry group of the system is Abelian, which corresponds to the system having cyclic variables, we derive an explicit expression for the required angular velocity in terms of the dynamic phase (an average of the mechanical connection) and the geometric phase (the holonomy of the mechanical connection). We show that one can also find such a frame if the reduced orbit is quasi-periodic and a KAM (Kolmogorov-Arnold-Moser) condition is satisfied The almost periodic case is also discussed. An important aspect of this procedure is how to use it in the presence of discrete symmetries. We show that, under appropriate conditions, the visualized orbit has, relative to a suitable uniformly rotating frame, the same temporal behavior and discrete symmetries as the reduced orbit. Since these spatio-temporal patterns are not apparent with repect to most frames, we call the phenomenon pattern evocation 相似文献
65.
J Marsden 《Canadian Metallurgical Quarterly》1995,4(16):948-953
This article examines the process of developing a nurse practitioner role. Areas which must be considered before and during the implementation of such a role are general and may be applied to any area of practice, although examples here are from the author's own practice. 相似文献
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A patient with a 2(1/2)-year history of painful spasms and rigidity of both lower limbs is described. Symptoms began after an episode of acute myelitis. The spasms--which were spontaneous and stimulus sensitive and occurred on voluntary action--involved the repetitive grouped discharge of motor units. Continuous motor unit activity was present at rest in the muscles of both legs, and cutaneomuscular reflexes were abnormal. This patient is similar to those recently reported as having stiffness and spasms of the legs due to a possible chronic spinal interneuronitis and provides further evidence that this kind of movement disorder may be caused by spinal cord pathology. 相似文献
68.
The effect of a 5-hydroxytryptamine7 (5-HT7) receptor-directed antisense oligonucleotide on rat behaviour and neuroendocrine function was investigated. Six days of intracerebroventricular 5-HT7 antisense oligonucleotide treatment significantly reduced [3H]5-HT binding to hypothalamic 5-HT7 receptors, whereas cortical 5-HT2C density remained unchanged. In rats on a food-restricted diet, both antisense and mismatch oligonucleotides reduced food intake and body weight compared with that in vehicle-treated controls by day 4 of administration. 5-HT7 antisense oligonucleotide administration did not affect exploratory or locomotor activity in photocell activity monitors on day 4 or elevated plus-maze behaviour on day 6 of intracerebroventricular treatment. 5-HT7 antisense oligonucleotide did not affect plasma corticosterone or prolactin levels or 5-HT turnover in either 5-HT cell body or terminal areas. These data demonstrate that intracerebroventricular 5-HT7 antisense oligonucleotide administration selectively reduced rat hypothalamic 5-HT7 receptor density without affecting any of the biochemical or behavioural measures. The results suggest that this antisense protocol could be a valuable tool to investigate central 5-HT7 receptor functions, and that this receptor is not critical for the control of neuroendocrine function or food intake. 相似文献
69.
Fuzzy inference is a method of reasoning with imprecise information. The mathematical operations of fuzzy inference can be stated in terms of generalized vector algebra, in which multiplication and summation are generalized to min and max operations. An optoelectronic H-tree architecture is ideally suited to perform these generalized vector operations in parallel and requires only a simple imaging optical interconnection. Appropriate data encodings and electronic circuitry permit large scale, pipelined systems. 相似文献
70.