A line vortex in a two-fluid system

This paper considers the classical problem of a line vortex in planar flow of a fluid. However, an interface is present at some finite radius from the line vortex, and beyond that is a second fluid of different density. The interface is therefore subject to shearing-type instabilities and may overturn as time progresses. A linearized inviscid theory is developed and reveals unstable behaviours, dependent on the parameters in the system. The non-linear inviscid problem is solved by a spectral method, and high-frequency modes are regularized by a type of filtering. In addition, a Boussinesq viscous model is presented and allows the overturning interface to fold. Results are discussed and compared with the predictions of the inviscid theory.     

Modeling the vulcanization reaction of silicone rubber

Characterization of the vulcanization process of silicone rubber was achieved through the modeling of dynamic DSC tests. The Kissinger equation and the Kamal‐Sourour model were used to determine kinetic parameters that fit the experimental data. The technique allows for the determination of the activation energy through Kissinger's model, which is then used to mathematically determine the other five parameters for the Kamal‐Sourour model. This novel technique finds a physically meaningful activation energy. The method generates a single set of parameters that accurately models all scanning rates tested (1, 2.5, 5, and 10 K/min). Five formulations of liquid silicone rubber as well as one solid silicone rubber were tested and modeled. For each material, the models generated fitting parameters that were in agreement with the dynamic DSC scans. The models were used to compare the processing of the liquid and solid silicone rubber. The characterization of both materials demonstrates the lower processing time, temperatures, and energy consumption when processing liquid silicone rubber, as compared to processing of hard silicone rubber. POLYM. ENG. SCI., 47:675–683, 2007. © 2007 Society of Plastics Engineers.     

Botulinum toxin in the management of the lower limb in cerebral palsy

The role of intramuscular botulinum toxin A in the treatment of 26 children with cerebral palsy was evaluated. The indication for injection was the presence of a dynamic contracture of lower-limb muscles interfering with positioning or walking. Spastic target muscles were identified by clinical examination and, in ambulant children, by gait analysis. Between 50 and 320 units of botulinum toxin were injected into each muscle group to a total dose of 100 to 400 units per child. The effects of injection were monitored by repeated clinical examination and gait analysis. There were no clinically detectable systemic side-effects, and all but one patient had a reduction in tone, which occurred within three days and persisted for two to four months. There were significant improvements in ambulatory status and in sagittal-plane kinematics. In some cases these gains persisted after the tone-reducing effects of the toxin had worn off.     

Verapamil, a phenylalkylamine Ca2+ channel blocker, inhibits ATP-sensitive K+ channels in insulin-secreting cells from rats

Radioisotopic and electrophysiological techniques were used to assess the effects of verapamil, a phenylalkylamine Ca2+ channel blocker, on K+ permeability of insulin-secreting cells. Verapamil provoked a concentration-dependent inhibition of 86Rb (42K substitute) outflow from prelabelled and perifused rat pancreatic islets. This property appears to be inherent to the phenylalkylamine Ca2+ channel blockers since gallopamil, a methoxyderivative of verapamil, but not nifedipine, a 1,4-dihydropyridine Ca2+ channel blocker, inhibited 86Rb outflow. The experimental data further revealed that verapamil interacted with a Ca2+-independent, glucose- and glibenclamide-sensitive modality of 86Rb extrusion. Moreover, verapamil prevented the increase in 86Rb outflow brought about by BPDZ 44; a potent activator of the ATP-sensitive K+ channel. Single-channel current recordings by the patch clamp technique confirmed that verapamil elicited a dose-dependent inhibition of the ATP-dependent K+ channel. Lastly, under experimental conditions in which verapamil clearly inhibited the ATP-sensitive K+ channels, the drug did not affect 45Ca outflow, the cytosolic free Ca2+ concentration or insulin release. It is concluded that the Ca2+ entry blocker verapamil inhibits ATP-sensitive K+ channels in pancreatic beta cells. This effect was not associated with stimulation of insulin release.     

Reviews

LAND INTO LANDSCAPE by John M. Hunter, George Godwin/Longmans, 1985, 182 pp, £25.00

EATON ESTATE: LANDSCAPE CONSERVATION PLAN: Abridged Version of the Landscape Consultants' Report by Ian Laurie et al, Department of Town and Country Planning: University of Manchester, 1983.

DISCOVERING THE VERNACULAR LANDSCAPE by John B. Jackson, 165 pages, Yale University Press, 1984, $16.50.

THE ECOLOGICAL IMPACTS OF OUTDOOR RECREATION ON MOUNTAIN AREAS IN EUROPE AND NORTH AMERICA edited by N. G. Bayfield and G. C. Barrow. Published by Recreation Ecology Research Group 1985, Report No. 9.     

Hemorrhage into a lumbar synovial cyst causing an acute cauda equina syndrome. Case report

Juxtafacet cysts of the lumbar spine have been reported with increasing frequency but their pathogenesis remains obscure. These cysts most frequently present with back pain, followed by chronic progressive radiculopathy or gradual onset of symptoms of spinal canal compromise. The authors report an unusual case of hemorrhage into a right L3-4 synovial cyst causing an acute cauda equina syndrome and describe its successful surgical treatment. The clinical, radiographic, and pathological features are discussed.     

The archaeological attributes of behaviour: difference or variability?

Phylogenesis, embryology and anatomy are emphasizing that two ligaments are found between the temporo-mandibular joint and the middle ear. These two oto-mandibular ligaments are named the disco-mallear ligament and the malleo-mandibular ligament. Originating from the first arch, these ligaments are not involved in the otologic manifestations of the temporo-mandibular joint syndrome. The disco-mallear ligament is a brake applied to the anterior excursion of the disc. When this disco-mallear ligament is stretched the disc can be displaced anteriorly breeding disc displacement, hypermobility and temporo-mandibular dislocation. The malleo-mandibular ligament is a remainder of the Meckel's cartilage: its role is not clear. When excessive forces are applying on the mandible, ossicles dislocation can be seen the forces being transmitted through it.     

Components of respiratory depression after narcotic premedication in adolescents

The biliary and urinary excretion and the choleretic effect of ioglycamide were studied in unanesthetized bile fistula dogs using stepwise increasing infusion rates to obtain multiple steady states. The results are compared with data from previously reported experiments in the same animals using iodoxamate and iodipamide. The rate of biliary excretion and the choleretic effect of ioglycamide are similar to those of iodipamide and iodoxamate. Like iodipamide and iodoxamate, the relation between infusion rate or plasma concentration and biliary excretion or concentration of ioglycamide are hyperbolic and can be fitted to saturation kinetics. Quantitatively, the excretion of ioglycamide and iodipamide are virtually identical. However, for any equimolar infusion rate or plasma concentration, more iodoxamate than ioglycamide is excreted in the bile. Despite the greater biliary excretion of iodoxamate, the maximum biliary concentration of ioglycamide, iodipamide, and iodoxamate is the same at low basal bile flow because the choleretic effects of the three compounds are equal. The data suggest that, theoretically, with any equimolar dose ioglycamide will be identical to iodipamide as a contrast material for intravenous cholangiography, but that iodoxamate may be superior to ioglycamide because more iodoxamate is excreted in the bile. This advantage of iodoxamate might become apparent clinically in patients with high basal bile flow or if smaller doses of the contrast material are used. However, at the presently recommended doses of the two compounds, it is unlikely that the use of ioglycamide for intravenous cholangiography will be any different than iodoxamate.     

SLASH: a program for analysing the functional groups in molecules

The authors examined the impact of a number of job stressors, including sexual harassment and gender-based discrimination, on female construction workers' level of job satisfaction and psychological and physical health. Results from a telephone survey with 211 female laborers indicated that having responsibility for others' safety and having support from supervisors and male coworkers was related to greater job satisfaction. Increased reported psychological symptoms were also related to increased responsibility, as well as skill underutilization, experiencing sexual harassment and gender-based discrimination from supervisors and coworkers, and having to overcompensate at work. Perceptions of overcompensation at work and job uncertainty were positively associated with self-reports of insomnia. Finally, sexual harassment and gender discrimination were positively related to reports of increased nausea and headaches.