Properties of slips of zirconia stabilized by oxides of rare earth metals

Casting properties of concentrated aqueous dispersions of zirconia stabilized by Y₂O₃, Si₂O₃, or a mixture of them are investigated. Optimum values of the pH, temperature, and slip concentration for the production of thin-walled vacuum-tight articles are established. Translated from Ogneupory, No. 3, pp. 12–15, March, 1995.     

Therapeutic approach in blast injuries of the ear

Otic blast injury is caused by arrhythmic air blast wave. The perforation of the tympanic membrane is the commonet finding associated with lacerations of mucosa in the middle ear. Makki [6] published 34 cases of myringoplasty after war blast injuries. However, healing of such perforations is common; Kerr [7] noted a healing rate of 83% after the blast injury. The aim of the study was to evaluate different therapic procedures of otic blast injuries. There were 74 patients with bilateral otic blast injuries, who underwent otomycroscopic examination. The following parameters were noted: Integrity of tympanic membrane and size of perforation, presence of haemorrhagic exudate in the middle ear and median value of conductive deafness (Table 2). Main symptoms, presented in Table 1 were: pain, deafness and otohaematorrhoea. The first group of 19 patients received antibiotics by parenteral way during 7 days according to the bacterial finding in ear exudate. Healing rate was dependent on the size of tympanic membrane perforation, and rated from 71% in perforation of one third of tympanic membrane to 25% in total perforation of tympanic membrane. Data are presented in Table 3. The second group of 24 patients received the same therapy as the first treatment, plus otomycroscopic removal of haemorrhagic exudate, lacerated middle ear mucosa, and repair of tympanic membrane lacerations. Healing rate was significantly better than the one obtained in the first group (Table 4). Persistent tympanic perforation, as indicator of failed therapy, was present in 5 (35%) of all examined ears with two thirds of tympanic membrane perforation in the first group, while in the second group the rate was 3 (12%). The third group received the same therapy as the second treatment, including administration of amicacyn into the external auditory canal. The results were statistically compared by chi 2 test, and we found that the second therapy protocol was significantly better. There was no significant difference between the second and the third therapy protocols. We found blast ruptures of tympanic membrane and auditory ossicles chain discontinuity in 88% of examined ears. In our material the high incidence of total tympanic membrane ruptures and subtotal ruptures (48%) is quite different in comparison to other authors [5-7]. We consider it as the effect of high power blast wave. Loss of conductive hearing was present in 91% of blast injured patients, while 7.4% of patients had mixed, predominantly senzoneural deafness. Consequently, in addition to mechanic blast injuries acoustic trauma could profoundly damage the inner ear. Spontaneous healing of tympanic membrane occurred in 71% of injured persons and this was a better result than the results obtained by other authors [3, 4, 6]. The spontaneous healing of tympanic membrane failed if infection of the middle ear occurred or blast caused the total tympanic membrane perforation. In the second and third therapy protocols significantly higher healing of tympanic membrane ruptures was evident; it rated from 88% to 91%. Better results could be explained by the effect of optimal healing conditions, based on removal of exudate from the middle ear and necrotic parts of tympanic membrane, completed by fitting of lacerated parts of tympanic membrane and antibiotic prophylaxis. Healing of tympanic membrane without scars and adhesions was more frequent than in patients treated only with antibiotics. Incidence of undesired outcome of persistent perforation of tympanic membrane was reduced. To prevent posttraumatic complications in the middle ear, we recommend early cleaning of margins, reposition of lacerated fragments of tympanic membrane, and removal of haemorrhagic exudate. Myringoplasty should be performed if spontaneous healing of tympanic membrane did not occur after 6 months. CONCLUSION: Otic blast injury was frequently found in war induced trauma. (ABSTRACT TRUNCATED)     

Effects of diversion and reperfusion of pancreaticobiliary juice on amylase release from isolated rat pancreas

Excitability of functionally different alpha-motoneurons was studied in 62 patients with gunshot injuries of nervous trunks of lower extremities both before and during process of rehabilitation by means of physical factors. The correlation of reactions of spinal cord motoneurons and the degree of injuries of nervous trunks was observed. Neuroapraxia of nervous trunks was accompanied by multidirectional alterations in reflex activity of large and small alpha-motoneurons. It was depressed in axonothermesis and lost in simultaneous full anatomic interruption of ischiatic nerve and trunks of both fibular and tibial nerves. Under influence of physical factors the function of motoneurons was normalized in neuroapraxia and was improved in axonothermesis of nervous trunks.     

The sensorimotor and cognitive integration of gravity

In order to demonstrate that gravity is not only a load acting locally and continuously on the body limbs, but is also used by higher levels of the nervous system as a dynamic orienting reference for the elaboration of the motor act, a review of several experiments conducted both in 1 g and 0 g are presented. During various locomotor tasks, the strategy that consists of stabilizing the head with respect to gravity illustrates one of the solutions used by the CNS to optimize the control of dynamic equilibrium. A question which remains to be solved when considering experimental results obtained in weightlessness concerns, however, the maintenance of motor schema that has evolved under normal gravity. Results have suggested that the concept of conservative processes, that would adapt postural control to weightlessness by using previously learned innate strategies, must be reconsidered during goal-oriented tasks. In fact, it is proposed that when conservative processes and existing solutions derived from a repertoire of terrestrial postural strategies do not provide efficient output, the CNS has to create novel strategies through a slow learning process. As with the study of postural control, three-dimensional arm reaching movements also illustrate the central representation of gravity. Indeed, gravity can be regarded as either initiating or braking arm movements and, consequently, may be represented in the motor command at the planning level. Finally, from a prospective point of view, there is a need to determine new experimental paradigms in order to study the specific motor control of man in space. It is suggested that the formulation of experimental paradigms should not consider man in space simply as a terrestrial biped.     

Examination of veins with magnetic resonance imaging and it's place in the diagnostic algorithm of patients with deep venous thrombophlebitis]

The aim of our study was to show the results of the Magnetic Resonance Angiography of pelvis and lower extremities. 21 patients with clinical signs of venous thrombosis were examined. The obtained results show the MRA is very useful in evaluation of venous flow.     

Complete single mode wavelength coverage over 40 nm with a superstructure grating DBR laser

The spectral characteristics of a widely tunable super structure grating distributed Bragg reflector (SSG-DBR) laser are investigated and the design considerations of the grating reflectors are given. By systematically adjusting the control currents of the two reflector sections and the phase section it is experimentally shown that every wavelength in an interval of 40 nm can be reached with a side-mode suppression usually better than 30 dB     

Co-ordinated economic and advance dispatch procedures

The paper deals with the problem of improving co-ordination between the online economic dispatch (ED) function and the very short-term advance dispatch (AD). Both procedures are formulated as optimal dispatching problems, but while a static model is used for the ED function, a dynamic model is employed in AD. The need to account for ramp-rate limits of thermal power generation even in the ED phase is satisfied by adding suitable penalty terms to the objective function of the classical ED problem. These penalties are proportional to the Lagrange multipliers associated with ramp-rate limits that are active at the AD solution. An efficient updating procedure is used to correct the penalization by taking the load forecast errors into account. The proposed co-ordination procedure can provide the snapshot ED with the long range perspective of AD without resorting to heuristic approaches. The procedure is validated by extensive testing carried out both on a small CIGRE test case and on a medium-large scale network representative of the Italian EHV system. Moreover, test results show that the CPU time requirements of the modified ED procedure are still suited to online applications     

Groupwork and computers: task type and children's performance

Abstract In the majority of British primary schools, children use the computer in groups of two or three. This is partly due to the lack of resources, that is, most classrooms still only have one or two computers to share between around 30 children. Groupwork on computers is also justified for pedagogic reasons. Previous research comparing children working in groups or alone has revealed an advantage for children working in groups although the work undertaken has generally been problem solving tasks. This investigation examined the performance of pairs and individual 6-year old children on a drill and practice program using a pre-test, intervention, post-test design. In comparison to the problem solving evidence, individuals were found to have a significant advantage over pairs during the computer-based task.