Operative Interference Research Articles

Engagement of the fetal head in the negro primigravida.

A prospective study into causes of non-engagement of the fetal head at term in the negroid primigravida showed no correlation with fetal birth weight nor with the pelvic brim inclination. However, there was a significant difference (p less than 0.05) between the mean head circumference of babies with heads which had not engaged (34.1 cm) and with those which had (33.1 cm). Labour was generally prolonged with a high head at term, but there was no increase in the incidence of fetal or maternal mortality and morbidity nor was it associated with an increase in the rate of operative interference. In addition, retrospective studies on pelvic brim inclination between 31 Nigerian primiparae and matched Caucasians at the Queen Charlotte's Maternity Hospital showed no statistically significant differences. It is suggested that an unengaged fetal head in early labour should not by itself be an indication for early delivery by caesarean section.

Assessment of scoliosis in children: low dose radiographic technique.

When scoliosis is clinically suspected in school children it may be necessary to radiograph the spine in the erect position to determine the degree of scoliosis and the presence of developmental abnormalities. The findings will be valuable to determine the future treatment of a child and to assess the necessity for operative interference. It is obviously desirable to devise a radiographic technique which will produce the information required with a low dose of radiation, bearing in mind the age of the children and the fact that subsequent radiography may be required on many occasions.

Factors causing and reversing vasoconstriction in unventilated lung

Vasoconstriction occuring a unventilated or hypoxic lung was studied in dogs and cats to elucidate mechanisms which both cause and reverse it. Lungs were perfused in vivo at constant pressure or constant blood flow; alternatively blood flow and pressure were measured with minimal operative interference. Stimulus-response curves of lung vessels to hypoxia showed a large response within the physiological range of P02 values. Vasoconstriction in unventilated lung caused by bronchial occlusion sometimes matched that caused by an equal degree of ventilation hypoxia but was sometimes greater. Responses to both stimuli varied widely between animals and in one animal at different times. This could be due to variable availability of a transmitter or variable presence of vasodilator substances. Both histamine and beta-adrenoreceptor stimulants caused pulmonary vasodilatation in unventilated lung. Histamine caused pulmonary vasoconstriction and vasodilatation in different circumstances which could be blocked respectively by H1 and H2 antihistamine drugs. Potent alpha- and beta-adrenoreceptor action on pulmonary vessels was demonstrated in both species. Alpha-adrenoreceptor blocking drugs caused dilatation and beta-adrenoreceptor blocking drugs caused vasoconstriction. The possible role of histamine and catecholamines in causing or reversing hypoxic vasoconstriction or in maintaining pulmonary vascular tone is discussed.

A ceramic restoration bonded by etched enamel and resin for fractured incisors

This report describes a technique for making ceramic restorations for fractured incisors without operative interference. The ceramic block is baked in the laboratory on a 24 karat gold matrix cast. A resin is bonded to a silane-treated porcelain block and etched enamel.

Assembly line sequencing for model mix

SUMMARY This paper describes a model sequencing algorithm for model-mix assembly lines. A new formulation of the sequencing problem is proposed, the objective function of which is to minimize the overall assembly line-length for no operator interference. Lower bounds for the overall line-length are developed. Two types of work station interfaces are considered; ‘closed’, where boundaries cannot be violated, and ‘open’ where defined boundaries do not exist—adjacent operators being allowed to enter each others apparent work areas without causing any interference. A complete factorial experiment was made on five factors to determine their influence on the overall assembly line length. These are, the number of models, the model cycle time deviation, the production demand deviation for each model, the operator time deviation, and the number of stations in the assembly line. The main conclusions of this experiment are discussed and recommendations made for the selection of parameters used in the design of model...

Geniohyoid and genioglossus muscles: Effect of experimental section

Abstract In five young sibling New Zealand white rabbits the muscular complex on the lingual side of the midline of the mandible was severed and a V-shaped piece of bone with the midline muscular attachments was removed from the lower border. In five control rabbits an incision was made down to the lower border but there was no further operative interference. There was no appreciable difference in weight gain between the two groups over a period of 8 weeks. All animals had difficulty in “swallowing” for 2 weeks, and two of the experimental animals gave evidence of such difficulty at 8 weeks. Firm muscular reattachments in the midline of the mandible had occurred in all the experimental animals when examined at the end of the eighth week.

Interactions Between Radiation Fields from Radioisotope Thermoelectric Generators and Scientific Experiments on Spacecraft

Spacecraft radioisotope thermoelectric generator interference in onboard instrument operation, using analytical models to determine necessary shielding

Termination in the prevertebral abdominal sympathetic ganglia of axons arising from the local (terminal) vegetative plexus of visceral organs. Peripheral reflex arcs.

Degeneration of synaptic axon terminals in the prevertebral (celiac and superior mesenteric) ganglia, occurring after operative interferences on visceral organs, shows that processes of ganglion cells (probably of Dogiel type II) located in the terminal ganglia of the gallbladder and the small intestine reach and establish synapses in the prevertebral ganglia. This finding is in accordance with the persistence of delicate axons in the peripheral stumps of visceral nerves two weeks after removal of the celiac ganglion. These results speak in favour of the existence of peripheral reflex arcs in the vegetative nervous system.

Extradural spinal cord compression by tumor. II. High daily dose experience without laminectomy.

COMPRESSION OF THE spinal cord is a medical emergency. If treatment is unsuccessful, transection of the cord results in lack of sensation, paralysis of limbs, and loss of sphincter control. When the compression is the result of lymphoma or metastatic carcinoma, management has classically consisted of laminectomy and tumor resection. Most centers utilize radiation therapy postoperatively in low to regular daily dose schedules as an adjuvant to the surgical attack, occasionally with the simultaneous administration of chemotherapy. The rationale evolved has been based upon the emergency nature of spinal cord compression and the dire consequences of failure to halt its progression. Because immediate decompression is considered essential, laminectomy is the procedure of choice. Some physicians believe that surgical decompression also reduces the risk of radiation edema due to tumor or spinal cord swelling, which may heighten the risk of further cord compression before relief is obtained. The statistics in the literature are such that any combination of surgery, radiation therapy, and chemotherapy can be justified. Each combined attack has had some measure of success, but there is no agreement as to a preferred therapeutic approach. Our results offer new clinical evidence which challenges the status quo of initial surgical management in favor of high daily dose radiotherapy without the need for laminectomy or systemic chemotherapy. Review of The Literature : Historical Perspective (Table I) Concepts in medicine are slow to change. The first description of compression of the spinal cord resulting from tumor was by Mongagni in 1769, while the first successful removal of a spinal cord tumor by surgery was achieved by Horsley in 1887. In subsequent decades, surgical approaches to spinal cord tumors were developed and refined. A pioneer and leader was Elsberg, who published his treatise on this subject in 1929. His philosophy, which has essentially guided the therapeutic effort in managing spinal cord compression by tumor, is reflected in the following statement: “Whenever the diagnosis of compression of the spinal cord by an extramedullary new growth has been made, operative interference should follow without more than the necessary delay.” This point of view was presented with some modification in his book of 1941, in which he advocated palliative measures for relief of pain (principally chordotomy in cases of malignancy). The lack of a consistent terminology for the description of the degree of impairment, coupled with the failure to quantify the therapeutic response of neurological recovery objectively in most reports, makes it difficult to compare different series. The numerous clinical variables in presentation and management are often lacking, and any attempt to tabulate such data is consequently handicapped when offered as a basis for historical review and criticism.

External Auditory Meatal Plasty

THERE MAY be a need to enlarge the external auditory meatus which can be absent or become insufficient in diameter because of a congenital defect, an acute or chronic infection, previous operative interference, or trauma. There may also be a need for an enlarged view of the middle ear following middle ear or mastoid surgery; for example, following a procedure such as Schuknecht's tympanoplasty. Present methods for enlarging the external auditory meatus consist of either free grafting of the skin taken from the arm, or just freeing the stenosis by incision, packing the meatus with bismuth iodide paste (BIPP), and inserting polyethylene tubing of suitable diameter or various other dilators.1The results of these procedures were not encouraging. The graft often shrank beyond what was expected despite generous allowance on cutting. It was often desquamated, sloughed, or became soggy and infected. This we felt was due in part to

Weaving Processes-Effects of Non-Preemptive Priority and Operator Interference on Output

Warp yarns are depleted in the weaving process and must be replaced. Principles of queueing theory are applied to warp beam replacement. Looms may be serviced with new warp beams on a first-come-first-served or on a priority basis. Comparative studies have been made to determine the queueing dis cipline that would maximize loom output or loom operating efficiency for the same number of repairmen. Monte Carlo methods have been used for examining the queueing process. The actual universe of looms was replaced by a mathematical model that was demonstrated to be theoretically equivalent to the actual universe. For the particular system investigated, the priority queue discipline proved to be marginally more economical than the first-come-first-served discipline. The effectiveness of simulation as a tool for this type of study has been demonstrated.

Pulse-Testing: A New Method for Describing Reservoir Flow Properties Between Wells

Abstract A new method of reservoir evaluation called pulse-testing has been developed for describing formation properties between wells. Pulse-testing utilizes a sensitive differential-pressure gauge at a responding well to measure and record the response generated by a series of flow rate changes (pulses) at an adjacent or pulsing well. Since the pulse-test instruments have a sensitivity of about 0.001 psi, pulses of several hours or less in duration will generate a measurable response in most reservoirs. For this reason, many well pairs can be tested in a short period of time with little interference in field operations. Comparison of pulse-test results to conventional testing methods shows that the pulses obey unsteady-state, compressible-flow theory and thus provide a measure of both transmissibility (kh/mu) and storage (phi ch). In addition, the method can be used qualitatively to describe communication across faults and between zones, and direction and magnitude of fracture trends. Introduction To obtain maximum usefulness of new reservoir analysis methods as well as to aid the field engineer in under-standing local reservoir anomalies, improved methods are needed to describe heterogeneities in specific reservoirs. Optimum well spacing, equipment specifications, well completion design and especially the economics of pressure maintenance and secondary recovery programs depend on the extent and location of the heterogeneities that affect flow behavior in the field. One method for obtaining a measure of areal reservoir heterogeneity is an interference test, in the simplest interference test, constant-rate production or injection is initiated at one well and the effect of this flow is measured as pressure vs time at another well. Thus, during interference tests the flow characteristics of the formation are determined in situ. Despite their obvious usefulness in reservoir delineation, interference tests have not enjoyed frequent usage. Reasons for this have been the weeks or months required in many fields to obtain a pressure response measurable with conventional gauges, and the interruption of routine field operation during the field-wide shut-in normally required during these long times. Also, only average properties of the relatively large volume of the reservoir disturbed during these long times can normally be obtained - variations in properties between individual wells cannot be delineated. To eliminate these drawbacks of conventional tests, a special reservoir description technique called pulse testing has been developed. Pulse-testing has several advantages that make it more convenient and practical for field use than interference tests. Valid tests are more certain because use of a series of flow disturbances gives rise to a diagnostic pressure response that can more readily be distinguished from unknown trends in reservoir pressure and other "noise." The time required is only a fraction of that for an interference test because a special, high-sensitivity differential pressure gauge can detect a much smaller pressure change. Variations in properties between individual wells can be delineated because of the relatively small volume of the reservoir disturbed during these short times. Finally, wells other than the pulsing and responding wells do not have to be shut in or carefully regulated. JPT P. 1599ˆ

Pathological principles in the management of spinal cord trauma.

Pathological principles governing early management of spinal cord trauma are: 1. The anatomical features of capacity, blood supply, and spinal cord structure. 2. The mechanisms by which the trauma is caused: flexion, extension and rotation, together with crushing, stretching and concussion. 3. The neural pathological pictures which emerge (i) Haematomyelia of the cord, with many manifestations caused by direct compression and direct interference with blood supply. (ii) Gross crushing of the cord. (iii) Subarachnoid and extra-dural haemorrhage. (iv) Longitudinal manifestations of stretching and colliquative necrosis. 4. The bony patterns: (i) The importance of the integrity of the neural canal after conservative management. (ii) The absence of continuing bony compression. In the later stages the final patterns that emerge are: (i) Gross crushing. (ii) Cysts. (iii) Peri-neural and peri-dural fibrosis. Applying these pathological principles, the author believes that a rational method of conservative treatment is, under most circumstances, the only method of management to be considered and explains the almost universal rejection of operative interference, since such interference can do little to affect the pathological state which has existed since the time of injury. Clinico-pathological facts which emerge are: (a) That movement of the fracture site is minimal with proper nursing. (b) Only a small percentage (7 per cent.) of a potentially unstable group of fractures in the cervical spine prove to be so after adequate management. (c) Non-union is a rarity in lumbo-dorsal fractures and stability occurs early after the time of injury.

Factors influencing the growth of epiphyseal cartilage.

SummaryThe growth of epiphyseal cartilage of femur and tibia is stimulated by operative interference and insertion of a tube into the knee joint.

PREMATURE OVIPOSITION FOLLOWING OPERATIVE INTERFERENCE WITH THE BRAIN OF THE CHICKEN.

Following the accidental discovery that electrical stimulation of the hen's preoptic brain induced premature (Ct) oviposition of the terminal egg of a 2-egg sequence, an analysis was made of relationships between times of stimulation and times and frequency of premature (Ct) lay, and, during the period of maximal response to stimulation thus determined, tests were made of the specificity of stimulus and brain region. Preoptic stimulation at 4–25 hr before Ct oviposition induced premature lay. The incidence of response increased fairly regularly from 25 hr (16%) to 7 hr (100%). Tests during the period of maximal response to stimulation showed that the response was not dependent on the passage of current or position of the electrodes, but was dependent only on operative interference with the cerebrum. Pentobarbital anesthesia, administered before the operation, did not block the response to stimulation. Seventy per cent of premature oviposition following preoptic stimulation over a period of 21 hr, and 92% ...

SOME PERTINENT OBSERVATIONS ON THE PATHOLOGY OF TRAUMATIC SPINAL PARALYSIS.

In an attempt to elucidate the pathological problem in spinal cord injury associated with fracture dislocations of the lumbo-dorsal and cervico-dorsal column, observations have been made on post mortem specimens at the Paraplegic Unit of the Royal Perth Hospital. These include 23 specimens in all stages of post accident state from one day to 20 years, observations being made on the bony, ligamentous, disc and neural lesions. Important in those observations are those in the neural tissue where it has been observed that the lesion is always one over some distance. Frequently there are cysts present, the cord is crushed in certain injuries, and there is frequently root damage of a number of types where an arachnoiditis and peridural scar are observed. This epidural scar has already been proved to be made worse by operative interference. Oedema and changes in the C.S.F. are commented upon. With these pathological problems in mind, comment is made on the natural history of the disease, and the use and disuse of operative interference in the early stages. The author believes that these observations prove quite conclusively that in very few cases (and mainly for bony reasons) will operative interference be justified. A series of pathological observations obtained from the literature are briefly commented upon.

TWO COMPONENTS IN THE DEVELOPMENT OF RAYCATARACT IN FROGS.

RECENTLY it has been shown in our laboratory that any intra-ocular operation on irradiated tadpoles seemed to result in the development of a ray cataract1. Later on, the same results were obtained in adult frogs and mice as well, in which an accelerated development of the aforementioned disease was also brought about by a fine pricking of the irradiated lens2–4. At the same time, judging by long-term observations on irradiated tadpoles and frogs, even a very heavy irradiation without subsequent operative intervention affects neither the transparency nor the structure of lenses. The experiments described here suggested to us that a direct relation existed between the degree of irradiation of the eye prior to operation and completeness of the opacity of the lens. Therefore, the question arose as to which doses of ionizing radiation—extreme, minimal, and maximal, combined with operative interference—provoked an accelerated development of the ray cataract.

DEATH FROM PULMONARY EMBOLISM ASSOCIATED WITH HYDATIDIFORM MOLE

Abstract This case is being reported first to call attention to the somewhat neglected aspects of trophoblastic invasion and deportation. With the increased invasiveness of the trophoblasts in a benign mole the chance of emboli formation would seem to be increased appreciably, particularly when associated with repeated manipulation and examination or attempted induction. It is felt that a more acute awareness of the likelihood of pulmonary emboli brings up the question of the advisability of early operative interference as against the long accepted, more conservative therapy of abortion of the mole followed by curettage.

Death from pulmonary embolism associated with hydatidiform mole

This case is being reported first to call attention to the somewhat neglected aspects of trophoblastic invasion and deportation. With the increased invasiveness of the trophoblasts in a benign mole the chance of emboli formation would seem to be increased appreciably, particularly when associated with repeated manipulation and examination or attempted induction. It is felt that a more acute awareness of the likelihood of pulmonary emboli brings up the question of the advisability of early operative interference as against the long accepted, more conservative therapy of abortion of the mole followed by curettage.

Rupture of the thoracic aorta.

The publication of this article is based upon the conviction that aortic rupture has generally been mishandled due to confusion concerning its diagnosis and prognosis. The anatomicopathology of our cases suggests the feasibility of rapid diagnosis of the condition and early operative interference. The major handicaps to successful saving of life with ruptured aorta have been (1) missed early diagnosis, and (2) delay while waiting for the disease to define itself. Those patients with partial aortic rupture who have survived are those in whom the lesion was of such modest nature that localized hemorrhage occurred and a false aneurysm formed. Aortic rupture is becoming more common in this era of high-speed travel, and the incidence may be expected to increase. Both highway and air travel, in which the body of the occupant is subject to large G-forces due to abrupt starts and stops is particularly productive of the lesion. For