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131.
W. F. Harris 《Ophthalmic & physiological optics》2003,23(3):251-261
Traditional treatments of spectacle magnification for distant objects consider only stigmatic spectacle lenses and they compare the retinal image size in a refractively fully compensated eye with the image size in the uncompensated eye. Spectacle magnification is expressed as a product of two factors, the power and shape factors of the lens. The power factor depends on the position of the entrance pupil of the eye. For an eye with an astigmatic cornea, however, the position of the entrance pupil is not well defined. Thus, the traditional approach to spectacle magnification does not generalize properly to allow for astigmatism. Within the constraints of linear optics and subject to the restriction that the eye's iris remains the aperture stop, this paper provides a complete, unified and exact treatment for optical instruments in general. It compares retinal image size in a generalized sense (including image shape and orientation) for any instrument in front of an eye with that of the eye alone irrespective of whether the instrument compensates or not. The approach does not make use of the concept of the entrance pupil at all and it allows for astigmatism and for non-alignment of refracting elements in the instrument and in the eye. The concept of spectacle magnification generalizes to the concept of instrument size magnification. Instrument size magnification can be expressed as the product of two matrix factors one of which can be interpreted as a power factor (as back-vertex power) and the other factor for which the name dilation factor is more appropriate in general. The general treatment is then applied to a number of special cases including afocal instruments, spectacle lenses (including obliquely crossing thick bitoric lenses), contact lenses, stigmatic systems and stigmatic eyes. In the case of spectacle lenses, the dilation factor reduces to the usual shape factor. 相似文献
132.
目的:探讨口腔粘结技术对儿童下颌骨骨折的治疗效果。方法:对37例儿童下颌骨骨折应用复合树脂粘结固定夹板,其中 4例应用复合树脂直接固定;13例实施尼龙丝结扎-复合树脂固定夹板;12例实施贴钩-尼克丝-复合树脂固定;3例应用金属丝弓一复合树脂单颌固定;5例实施牙列贴钩 带钩丝弓-复合树脂颌间弹性牵引。结果:37例儿童下颌骨骨折中有35例咬合关系恢复正常,2例 有轻度错(牙合),经调(牙合)后咬合关系正常。结论:儿童混合牙列时期乳、恒牙交替及牙齿形态特殊,又儿童下颌骨中含有牙胚不易手术治疗,而常规牙弓夹板固定困难,因此,应用复合树脂粘结固定夹板治疗儿童下颌骨骨折是一项简易、高效的技术。 相似文献
133.
Following the discovery of X-rays in 1895 by Wilhelm Röntgen the value to the military surgeon of the new technique was soon realised. The localisation of retained bullets by radiography avoided inappropriate exploration of the wound. The X-rays were first used on casualties from the Abyssinian War of 1896 and the developing radiological technology was progressively applied to military surgery. In addition the needs of warfare stimulated the development of all aspects of radiology. 相似文献
134.
Steven J. Davidson MD MBA Frank L. Zwemer Jr. MD MBA Larry A. Nathanson MD Kenneth N. Sable MD Abu N.G.A. Khan MD MS 《Academic emergency medicine》2004,11(11):1127-1134
Physician-generated emergency department clinical documentation (information obtained from clinician observations and summarized decision processes inclusive of all manner of electronic systems capturing, storing, and presenting clinical documentation) serves four purposes: recording of medical care and communication among providers; payment for hospital and physician; legal defense from medical negligence allegations; and symptom/disease surveillance, public health, and research functions. In the consensus development process described by Handler, these objectives were balanced with the consideration of efficiency, often evaluated as physician time and clinical documentation system costs, in recording the information necessary for their accomplishment. The consensus panel session participants and authors recommend that 1) clinical documentation be electronically retrievable; 2) selection and implementation be evidence-based and grounded on valid metrics (research is needed to identify these metrics); 3) the user interface be crafted to promote clinical excellence through high-quality information collection and efficient charting techniques; 4) the priorities for integration of clinical information be standardized and implemented within enterprises and across health and information systems; 5) systems use accepted standards for bidirectional, real-time clinical data exchange, without limiting the location or number of simultaneous users; 6) systems fully utilize existing electronic sources of specific patient information and general medical knowledge; 7) systems automatically and reliably capture appropriate data that support electronic billing for emergency department services; and 8) systems promote bedside documentation and mobile access. 相似文献
135.
Neurosurgery has traditionally been at the forefront of advancing technologies, adapting new techniques and devices successfully
in an effort to increase the safety and efficacy of brain and spine surgery. Among these adaptations are surgical robotics.
This paper reviews some of the more promising systems in neurosurgical robotics, including brain and spine applications in
use and in development. The purpose of the discussion is twofold—to discuss the most promising models for neurosurgical applications,
and to discuss some of the pitfalls of robotic neurosurgery given the unique anatomy of the brain and spine. 相似文献
136.
137.
138.
感染日本血吸虫的家兔治疗前后肝纤维化动态观察 总被引:1,自引:1,他引:0
感染日本血吸虫的家兔治疗前后肝纤维化B超声像图模型、血清MAO水平及病理学结果表明,血吸虫引起的肝纤维化变化过程与血清MAO水平升降趋势趋向一致,均在18周达到高峰。解剖与病理学检查结果基本相符,血吸虫性肝纤维化形成后,只要及时给予杀虫治疗,肝纤维化部分可发生逆转。 相似文献
139.
M. Uhl K. H. Allmann C. Ihling M. P. Hauer W. Conca M. Langer 《Skeletal radiology》1998,27(12):677-682
Purpose. To assess the accuracy of different MR sequences for the detection of articular cartilage abnormalities in rheumatoid arthritis.
Design and patients. Ten metacarpophalangeal joints and 10 metatarsophalangeal joints (specimens from arthritis patients undergoing ablative joint
surgery) were examined with a fat-suppressed (FS) 3D FLASH, a FS 3D FISP, a FS 2D fast spin-echo T2-weighted, and a 2D FS
spin-echo T1-weighted sequence. Each cartilage lesion and each cortical lesion was graded from 0 to 4 (modified Outerbridge
staging system). Subsequently, the results of each sequence were compared with the macroscopic findings and statistically
tested against each other. Results. The study shows that 3D gradient-echo sequences with fat suppression were best for imaging and grading of cartilage lesions
in arthritis of the small joints of the hands and feet. Using 3D techniques, all grade 2, grade 3, and grade 4 lesions of
cartilage or cortical bone were detected. Conclusion. FS 3D gradient-echo techniques were best for the detection and grading of hyaline cartilage and subchondral bone lesions
in rheumatoid arthritis. MRI has a great potential as an objective method of evaluating cartilage damage and bone erosions
in rheumatoid arthritis. 相似文献
140.
A wireless device for the assessment of tardive dyskinesia by means of digital image processing is presented. Four skin-cream dots placed around the subjects' mouth are recorded by a video camera. The image is passed to a framegrabber with a signal processor, where it is converted from analogue to digital. A fast spot-detecting algorithm implemented on the signal processor tracks the dots and passes the information to a personal computer, where a Fourier transformation is performed to calculate the frequency spectrum of the movements. The device provided detailed information on the magnitude and on the frequencies of the movements. Data from a longitudinal investigation suggest a higher sensitivity and reliability than conventional rating scales to detect and evaluate abnormal perioral movements. The device might be useful for the early detection, for the longitudinal assessment (p.e. clinical trials) and in some cases for the differential diagnosis of tardive dyskinesia, thus providing a tool for both research and clinical purposes. 相似文献