RESUMO
A synchronous polarimeter was set up for the measurement of small rotation angles of the polarization plane of light. The polarimeter is based on a polarizer-Faraday modulator-analyzer structure with a synchronous detection scheme, which produces a linear system response. The theoretical background is studied, and the system performance is investigated experimentally. We achieved an accuracy of the order of 10(-4) deg, or 5 mg/dl of glucose in a 1-cm light path.
RESUMO
We describe a novel optical sensor based on the Faraday effect for measuring ac. The sensing element is a piece of material of high Verdet constant placed between polarizers. When the angle between the polarizers differs by 45 degrees, a signal of twice the frequency of the ac is generated--in addition to the usual signal with the same frequency as the current. The quotient of these two signals allows a normalized output to be obtained that is proportional to the amplitude of the current. Experimental results demonstrating the practicality of the procedure are presented.
RESUMO
Based on the Faraday effect for measuring ac current, we describe a fiber-optic sensor that uses laser-diode intensity modulation to perform heterodyne signal detection. The sensor output at the carrier frequency is used as a reference signal to normalize the results. The sensing element consists of a few coils low-birefringence fibers between polarizers. We built the current sensor described above and tested its performance--sensitivity and noise--as functions of the angle between polarizers.
RESUMO
Three patients with occult severe hyperflexion sprain of the lower cervical spine are described. Because the spine radiographs obtained at the time of trauma were physiologically normal, the complete instability was initially overlooked. The authors recommend an algorithm for adequate diagnosis of this condition. Posterior cervical fusion is the treatment of choice.
Assuntos
Vértebras Cervicais/lesões , Instabilidade Articular/etiologia , Entorses e Distensões/diagnóstico por imagem , Adulto , Algoritmos , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Entorses e Distensões/complicaçõesRESUMO
An unusual case of anterolateral fracture-dislocation of the lumbosacral junction is reported, and seven additional cases from the literature are discussed. The mechanism of injury is forced hyperflexion and shear. The prevalence of neurologic involvement is high, as is the number of fractures of the adjacent spinal elements and the occurrence of disk fragments in the spinal canal. The value of plain radiography and computed tomography in diagnosis and planning treatment is illustrated.
Assuntos
Luxações Articulares/diagnóstico por imagem , Vértebras Lombares/lesões , Sacro/lesões , Fraturas da Coluna Vertebral/diagnóstico por imagem , Adulto , Humanos , Masculino , Tomografia Computadorizada por Raios XRESUMO
The dynamic ASIF-BM external fixator incorporates telescopic tubes for axial dynamization and angled bayonet screws to keep the tubes parallel to the bone axis, that is essential for gliding, and adjustment of rotation. The results after treatment of 70 type II and III open tibial fractures with static ASIF and dynamic ASIF-BM frames were analysed. Of the fractures, 32 were treated with the delta ASIF static frame, the other 38 with delta and uniplanar dynamic ASIF-BM frames. The groups were found to be comparable. The results of the study confirm that tubular external fixation is a safe method for treating the bone and soft tissue lesions in such fractures. The comparative study shows that axial compression, using the ASIF-BM device, with early weight bearing, gave a higher rate of union (97 per cent against 87 per cent with the ASIF frame), a shorter healing time (19 weeks against 29 weeks with the ASIF frame) and a decreased need for bone grafting (21 per cent against 84 per cent with the ASIF frame). The incidence of pin track infection was also decreased in dynamic frames. Thus it seems that the ASIF-BM dynamic fixator has a valuable part to play as a definitive mode of therapy for severe open fractures of the tibial shaft.
Assuntos
Fixadores Externos , Fixação Interna de Fraturas/instrumentação , Fraturas Expostas/cirurgia , Fraturas da Tíbia/cirurgia , Adolescente , Adulto , Idoso , Desenho de Equipamento , Feminino , Fixação Interna de Fraturas/métodos , Consolidação da Fratura , Fraturas não Consolidadas , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Fatores de TempoRESUMO
Two cases of ipsilateral open fracture of the femur and tibia treated using the dynamic ASIF-BM tubular external fixator are described. Results were very good, with short periods of occupational disability. These cases support primary stable osteosynthesis of these simultaneous fractures and the value of dynamic axial external fixation as a definitive treatment of open fractures of the femur and tibia shaft, either isolated or simultaneous.
Assuntos
Fraturas do Fêmur/cirurgia , Fixação Intramedular de Fraturas/instrumentação , Fraturas Expostas/cirurgia , Fraturas da Tíbia/cirurgia , Acidentes de Trabalho , Adulto , Feminino , Fraturas do Fêmur/diagnóstico por imagem , Fraturas do Fêmur/etiologia , Fraturas Expostas/diagnóstico por imagem , Fraturas Expostas/etiologia , Humanos , Masculino , Motocicletas , Radiografia , Fraturas da Tíbia/diagnóstico por imagem , Fraturas da Tíbia/etiologiaRESUMO
A series of 14 cases of open fractures of the shaft of the femur and another group of 13 cases of infected non-union of the shaft of the femur are reported. They were treated with the AO tubular external fixator. The complications and results are assessed and it is concluded that the AO external fixator system has a valuable part to play in these difficult cases.