Ink-Jet Printing System?An Analytical Computer Model

An analytical computer model of an ink jet printing system was created. Based upon the values of 13 input parameters, the program delivers predictions of the forces acting on individual drops and their resulting dynamic behavior. Predictions of drop displacements and flight times were used to infer drop pattern appearance resulting from a given input signal. The computer model was based upon theoretical work plus extensive empirical measurements. Drop behavior was predicted with modest accuracy. An improved understanding of ink jet printing systems and numerous recommendations for their use were also derived in this study.     

An Analysis of Chorioretinal Thermal Response to Intense Light Exposure

An analytical expression has been obtained for the transient temperature distribution produced when the retina is irradiated by a high-intensity light source. The following factors are included in the analysis: (1) structurally the fundus consists of layers of material which have different physical properties, (2) absorption of energy from the light beam follows the Beer-Lambert law, (3) energy is absorbed in the sclera as well as in the pigment epithelium and choroid, (4) heat is removed from the fundus by blood circulating through the capillaries of the choroid, and (5) intensity of the light source may vary with time. Computed values indicate that absorption of energy in the sclera and removal of heat by convection are both important for longer irradiation times, which agrees with recent experimental observations. The asymptotic response to a train of pulses is presented also.     

A case of reversible deafness in cystic arachnoiditis (author's transl)

A patient studied preoperatively by a neuro-otological test battery showed signs of an extensive cerebellopontine angle tumour. During the operation dense fibrotic tissue was found extending from the choroid plexus to the right acoustic nerve, which was freed and thus decompressed. Postoperatively, low frequency hearing improved markedly in the right ear. In contrast to the well-known documented cases of successful decompression of the optic nerve it has not been possible up to now to achieve a successful outcome in similar procedures on the acoustic nerve. In the described case the fibrotic lesion had obviously just caused reversible damage to the myelin sheaths of the eighth nerve, which can be interpreted as "neurapraxia" (Seddon, 1943). Further investigations in regard to the systematic elucidation of possibly reversible damage to the acoustic nerve are currently being performed at the IInd ENT department of Vienna University.     

Practice of computer use in radiotherapy planning

The main problems of radiotherapy planning are discussed with respect to use of computers now being available for a greater number of centers. One of the most essential premises is apart from clear ideas on a modern target volume concept - a sufficiently high speed in producing realistic summarized isodose contours for any radiation therapy arrangement in any individual patient's cross section outline. This problem being solved, those individual summarized isodose figures have to be critically evaluated and therefore the importance of applicable meaningful optimization criteria come into account. The properties of such criteria, which must be quantifiable, generally applicable and really relevant for judgement on quality of a plan, had to be accepted, before automatic optimization procedures could be developed; principles involved are presented. By means of a short series of examples, namely 60Co fixed field combinations with and without use of wedges, combinations of arc therapy for a number of clinical tasks. It has been pointed out, that most experienced estimate by the eye would have been by far insufficient when compared to the automized computer optimization when using such simple criteria as 1. homogeneity of absorbed dose within target volume, 2. numerically limited absorbed dose within areas of risk, 3. as low as possible radiation effects to all "outside areas". It seems to be a real danger, that so called isodose libraries, how high their merits might be estimated, may change into an "isodose bcemetery", unless we'll be successful for each individual clinical case by use of computers, which are now prepared to supply the best possible variant of the standard plan or the primary radiotherapy idea. Regular use of computers in such a way will furthermore give an incomparable documentation material.     

Total hip replacement with isoelastic prosthesis in animals (author's transl)

Uncemented fixation and low-fraction materials are the basis of this experiment. Plastics with an elasticity similar to the bone ("isoelasticity") show very propitious material qualities. The direct cementless incorporation of test bodies must be checked. In 63 sheep isoelastic total hip joints were implanted. After 2 till 51 weeks the animals were sacrificed and 44 specimen of hips and organs were explored macroscopically, radiologically, spherimetrically and histologically. The result was: 1. Plastic hip prosthesis are incorporated in the bone, but the boundary layer is built by a collagenous fiber tissue. 2. Loosening brings resoption of the bone and expansion of the structural changed soft tissue. 3. The transformation of the femoral cortex to osteoporosis is considered possibly as the consequence of an insufficient biological transfer of the weight. 4. Fractures of the femoral prosthesis-stem could not be observed. 5. The radiology allows at the pelvis prosthesis a concret statement concerning stability, on the femoral part a probable one. 6. The abrasion is minimal, the tissue reaction to abrasion products is unessential. 7. Small abrasion particles are carried of by the lymph tract and stored in the first regional gland. A more distant spreading is not demonstrable.     

Misdiagnosis of intraocular iron foreign bodies (author's transl)

Out of 393 intraocular foreign bodies (1961-1975) 361 were magnetically removed and 32 non-magnetically (copper 7,brass,2,lead 5, glass 10, stone 3, wood 4 and plastic 1).60% of the foreign bodies were caused by hammer and chisel injuries.73 foreign bodies were diagnosed too late, in 71 cases no x-ray was made. The incidence of complications (infection, siderosis, retinal detachment was considerably increased where the foreign bodies were removed late. From the 73 foreign bodies (18.5%) the patient did not consult a doctor in 37 cases because of "insignificance". 4 times the family doctor was consulted, who treated the patient symptomatically. In 4 cases occurring in the weekend no eye-specialist could be ostensibly found. In 26 cases the ophthalmologist performed no x-ray control, and small foreign bodies were twice described as "x-ray plate artefacts" from the roentgen specialist. It must be an absolute rule in the eye-doctor's practice that every injury received while working with metals necessitates an x-ray control!     

The problem of functional achlorhydria]

It was examined whether in anatomically intact specific adenic parenchyma of the gastric mucosa achlorhydria can persist after maximal stimulation or whether there is support to the conception of functional achlorhydria ("functional anacidity") furthermore. Relating to the anatomic structure of the gastric mucosa secretion of chloric acid was studied after submaximal and maximal stimulation in 101 cases. It was shown that there is no correlation between the morphology and the secretion of chloric acid in anatomically intact gastric mucosa after submaximal stimulation. In 18 cases out of 28 only the secretion of acid was in correspondence to the histological condition. In two cases out of 37 with atrophic gastric mucosa diverging results were found. After maximal stimulation with histamine chloride and pentagastrine one out of two cases with histologically intact mucosa showed normochlorhydria after seven days, whereas the second case remained achlorhydric. These results must be interpreted as functional achlorhydria. Submaximal stimulation of gastric secretion as it is practised today does not allow corresponding consequences concerning the morphological condition of the gastric mucosa. Discrepant results are found especially in histologically normal mucosa. There is more congruence in atrophic gastric mucosa.     

Safety on ladders: an ergonomic design approach

By studying the interactions between the user and a ladder or steps, with different shaped rungs, the author determines a preferred rung shape for improved ladder safety.     

Cracking in and around the thermally grown oxide in thermal barrier coatings: A comparison of isothermal and cyclic oxidation

In the present paper the time and temperature dependent evolution of the microstructure of TBC systems and especially of post-experimentally determined physical defects in and around the TGO for both isothermal and cyclic exposure conditions are investigated. Specimens with APS- as well as with PVD-topcoats have been oxidised between 950 and 1100°C up to a maximum duration of 5000 h followed by extensive scanning electron microscopy and subsequent interactive image analysis to measure the maximum crack lengths in and around the TGO. These cracks are additionally classified with respect to their local orientation in the TGO or its vicinity. The results of isothermal and cyclic test conditions show a number of similarities in results e.g. an unsystematic occurrence of inwardly growing, “cauliflower like” oxide or the most frequently occurring type of cracks in APS systems. Nevertheless substantial differences concerning the final failure, microstructure, crack growth behaviour and finally life time of the component between isothermal and cyclic test conditions exist. Some indications were found, that for this particular bond coat occurance of inwardly growing oxide intrusions increases the adherence of the TGO.