One hundred years of orthopedics in the Netherlands. IV. Spinal abnormalities]

In recent years there has been spectacular progress in the approach to various disorders of the spinal column. Owing to improved methods of osteosynthesis there is no longer so much need for long periods of postoperative bed rest. Of all the scolioses, idiopathic scoliosis is most common. The vast majority of these cases are not clinically significant. What is seen in the remaining cases if left untreated is a progression in the curvature during growth. Progressive idiopathic scoliosis can be effectively treated using conservative methods. Screening at school is an important part of this process. If the curvature proves progressive and skeletal growth is not complete a brace can be prescribed. Use of this strategy and form of treatment can avoid progression of the curvature and development of serious deformities. This conservative therapy has markedly reduced the need for corrective surgery. Scheuermann's disease is characterized by a fixed dorsal thoracic kyphosis. Progressive Scheuermann's kyphosis can be effectively treated using a brace. The majority of fractures of the vertebral bodies can be treated conservatively. However, serious fractures normally require surgical intervention. In the industrialised Western world, low back pain is a major health problem and the foremost cause of disability and unfitness for work. Low back pain caused by degenerative disease of the spinal column should be treated using a multidisciplinary approach. The development of advanced operative techniques and osteosynthesis methods has made it possible to treat metastases of the spine surgically. The effects of this treatment on the quality of life are encouraging.     

Antibiotic pharmacodynamics in cerebrospinal fluid

The CSF half-lives of lipophilic agents, such as quinolones, are similar to those in serum and peak concentrations in CSF are achieved relatively quickly. In contrast, the pharmacokinetics of hydrophilic agents (beta-lactams and vancomycin) in CSF often differ from those in serum. In particular, the half-lives of these agents in CSF tend to be extended, and the time to achieve peak concentrations in CSF is delayed. Hydrophilic antibiotics, such as beta-lactams, penetrate poorly through the BBB, but CSF penetration is significantly increased in the presence of inflammation. In contrast, lipophilic antibiotics, such as quinolones, enter the CSF more efficiently and their penetration is not inflammation dependent. The pharmacodynamic properties of antibiotics in CSF are generally similar to those in other body sites; beta-lactam agents and vancomycin are time-dependent, whereas the quinolones and aminoglycosides are concentration-dependent. However, a notable difference from infections in other sites is that quinolones have a short PAE in CSF and need to continually exceed the MBC for maximal effectiveness. Thus, in CSF, quinolones demonstrate features of both concentration-dependency and time-dependency, evidence that the AUC/MBC is an important predictor of effectiveness. With the exception of quinolones, many antibiotics appear to have prolonged sub-MIC effects and longer half-lives in CSF than in serum, suggesting that dosing intervals longer than those used traditionally would be effective in meningitis. However, this requires clinical verification.     

The pacemaker inverse problem--computer diagnosis of paced electrocardiograms

Like the electrocardiographic inverse problem, the object of which is the algorithmical analysis and diagnosis of the electrocardiogram (ECG), the pacemaker inverse problem is the analysis of the ECG in order to establish details of heart-pacemaker interaction (HPI) with special reference to the diagnosis of pacemaker failure. The solution to this problem is of practical importance, since it is often difficult to evaluate such records clinically. The ECG patterns of natural cardiac depolarizations and paced events may not be distinguishable and many combinations of potential pacemaker response must be taken into account. A computer system providing automatic analysis of the HPI, based on ECG data, has been developed and implemented on an IBM PC AT computer. The system uses a complex algorithm which enables the evaluation of all possible combinations of HPI events, and establishes for each of these combinations its correspondence to the specified pacemaker algorithm. The system is written in Pascal and its source text has approximately 11,000 lines. The first version of the system has been tested with algorithms of the dual chamber cardiac pulse generator AUTIMA-II (Telectronics). The interactive input of the system allows the pacemaker algorithm and the ECG, in the form of timing of "definite" and "possible" sensing events and pacemaker pulses, to be specified. The analysis establishes whether the device operates correctly within permitted error. Should one or more correct explanations of the specified case be found, the system prints simplified patterns of the ECG accompanied by a simulated marker channel tracing the possible HPIs.     

Property stabilization in filled,drawn polyethylene

Mechanical properties of high density polyethylene (HDPE) extended to draw ratios in the 20–40 range have been determined and compared with corresponding properties of the polymers containing particulates including rutile, carbon black, iron oxide, and mica. Shrinkage of drawn structures was studied to temperatures near the fusion of the polymer host. The degree of interaction at polymer/additive interfaces was varied by surface coating certain of the solids with standard coupling agents. Solids were found to increase tensile moduli and to decrease shrinkage, particularly at higher exposure temperatures. The magnitude of changes due to the presence of solids was shown to depend on the apparent interaction at contacts between host and additive. In a dispersion–force matrix, like HDPE, benefits were optimized when the particulates were amphoteric or neutral, rather than having pronounced acid or base interaction potentials.     

Gravity optimised particle filter for hand tracking

This paper presents a gravity optimised particle filter (GOPF) where the magnitude of the gravitational force for every particle is proportional to its weight. GOPF attracts nearby particles and replicates new particles as if moving the particles towards the peak of the likelihood distribution, improving the sampling efficiency. GOPF is incorporated into a technique for hand features tracking. A fast approach to hand features detection and labelling using convexity defects is also presented. Experimental results show that GOPF outperforms the standard particle filter and its variants, as well as state-of-the-art CamShift guided particle filter using a significantly reduced number of particles.     

Morphological and mechanical studies of surface treated mica reinforced high density polyethylene

Morphological studies of high density polyethylene (HDPE) reinforced by mica flakes has been investigated. The mica flakes were surface treated by silane and titanate coupling agents. Effects of these treatments on the polymer-mica interface is discussed. It is found that surface treatment, particularly silane treated composites, have better adhesion between the reinforcing agent and the polymer matrix. This effect can only be detected when the mica concentration is higher than 20 weight percent. This interfacial adhesion could not be seen across the surface of the sample but only when the measurements were made parallel to the surface.     

Corrosion and mechanical behavior of fusion bonded epoxy (FBE) in aqueous media

In recent years there have been many reported cases of corrosion failure in cement concrete pipelines. In the majority of cases, the failures have been attributed to rebar corrosion which is caused by the permeability of chloride from low resistivity soil and subsequent attack on a passive layer on an iron bar in the structure. As a possible alternative to cementitious materials, some organic coatings based on olefin, vinyl or epoxy-based polymers have been considered. However, due to a paucity of data on the behavior of these coatings in aqueous media— particularly product water—the possibility of their application in water transmission systems in the Kingdom has not been fully exploited. This paper deals with the studies carried out on the corrosion and mechanical behavior of fusion bonded epoxy (FBE) coating on steel in aqueous media which include product water, distilled water and saline water. The mechanical testings on coating include adhesion, bending and cathodic disbondment testings. The corrosion studies include immersion testing under static and dynamic conditions, autoclave tests and accelerated (salt-fog) tests. The analysis of results indicates chemical inertness of FBE coating in either of the aforementioned water used during testing, good adhesion and no damage to the coating during bending. Cathodic disbondment tests indicate that FBE coating sustains under cathodic protection (CP) conditions. In general, the results of mechanical and corrosion tests indicate that FBE is a promising material for internal coating on steel in water transmission systems.