Different Types Of Operations Research Articles

TUMORS OF THE NASOPHARYNX

Tumors of the nasopharynx present a perplexing problem from the standpoints of both diagnosis and management. The anatomical peculiarities of the nasopharynx make adequate clinical examination and early diagnosis difficult. When the symptoms develop, the tumor may have reached such an advanced stage that the results of treatment will be unsatisfactory. Diagnosis is rarely made clinically because the complaints are seldom related to the nasopharynx. The difficulties encountered in the recognition of these lesions have been shown by New. 42 In his series of 194 patients with malignant tumors of the nasopharynx, 185 different types of operations had been performed for relief of symptoms prior to admission to the Mayo Clinic. For practical purposes, any patient with unexplained otological complaints should have a thorough examination of the nasopharynx. When a patient complains of nasal obstruction, epistaxis, persistent sore throat, or other nasopharyngeal symptoms, one should suspect the possibility of a tumor of the nasopharynx with extension to the oropharynx. Cranial nerve paralysis, particularly of the sixth to third nerves, should lead to a suspicion of a nasopharyngeal tumor. Any enlargement of the cervical lymph nodes should merit a nasopharyngeal examination. A palpable deep node under the sternocleidomastoid muscle is almost pathognomonic of a malignant tumor of the nasopharynx. 15 Roentgen examination is a valuable adjunct in the diagnosis of these tumors. In interpreting roentgenograms of the nasopharynx, a knowledge of regional anatomy of the head and neck and of the routes of spread of the disease is imperative. For a presumptive diagnosis, demonstration of a soft tissue mass is essential; bony sclerosis of the base of the skull is highly suggestive of a malignant process, and destruction of the base of the skull is reliable evidence of neoplastic disease. For the final diagnosis of tumors of the nasopharynx, the clinical and roentgen findings must be confirmed by tissue biopsy. Once the diagnosis is established, the gross limits of disease as demonstrated roentgenologically provide a firm basis for treatment planning.

Design of Aerobic Wastewater Treatment Facilities

This paper is concerned with the various aspects of designing biological treatment facilities capable of removing organic contaminants from industrial wastewaters. Outlined are a sequential approach to developing a conceptual plan, formulating design criteria, and estimating capital and operating costs. Wastewater characterization data, which are a necessary prerequisite for developing basic design concepts, will be considered with respect to the functioning of the treatment processes. This will include the most prevalent organic parameters and some of the pertinent inorganic parameters which are meaningful in terms of plant operation and effluent quality criteria. The necessary bench or pilot scale studies which must precede final design will be discussed. These include the determination of oxygen and mixing requirements, hydraulic retention times in the various unit processes, and sludge-handling requirements. After translation of this information to the sizing of the various basins, mixing and oxygen-transfer equipment and other mechanical appurtenances will be discussed. Some general aspects of estimating the capital costs for these treatment processes will be included. Additionally, many of those expenditures which can be anticipated with respect to maintenance and operation of different types of aerobic plants will be stated.

Inguinal and femoral hernias. Results following 238 preperitoneal radical operations.

The fact that so many different types of operation are employed for the repair of inguinal and femoral hernias can possibly be interpreted as an indication that good results are not easily obtained and that there is still a need for important methods. In contrast to what one tends to assume, such factors as heavy work, obesity, and advanced age do not influence the recurrence rate to any great extent according to Borgstrom 1 and Ryan. 2 On the other hand Marsden 3 and Jernberger and Liljedahl 4 found an increase in the frequency of recurrence with advancing age. Recurrence is uncommon following hernia operations in children, while in adults, direct hernias recur more often than indirect ones. Ryan 2 stated in his analysis of 369 recurrent hernias that direct hernias were 2½ times as common as in a large series of primary hernias. Large hernias recur more often than small

On the Psychological Importance of Time in a Time Sharing System

One of the most important problems in the design and/or operation of a computer utility is to obtain dynamical characteristics that are acceptable and convenient to the on-line user. This paper is concerned with the problems of access to the computer utility, response time and its effect upon conversational use of the computer, and the effects of load on the system. Primary attention is placed upon response time; rather than a single measure, a set of response times should be measured in a given computer utility, in correspondence to the different types of operations requested. It is assumed that the psychological value of short response time stems from a subjective cost measure of the user's own time, largely influenced by the value of concurrent tasks being postponed. A measure of cost (to the individual and/or his organization) of the time-on-line required to perform a task might thus be derived. More subtle is the problem of the user's acceptability of given response times. This acceptability is a function of the service requested (e.g., length of computation), and variability with respect to expectations due both to uncertainty in the user's estimation and to variations in the response time originated by variable loads on the system. An effort should be made by computer-utility designers to include dynamic characteristics (such as prediction of loads and their effects) among their design specifications.

Theoretical Considerations of the Three-Level Maser Detector for the Far-Infrared

In the case when the pumping transition in a three-level system of a molecule does not exactly coincide with the output frequency of a maser oscillator, four different types of operation at off-resonance of the three-level maser detector are discussed. At first the use of pressure broadening is considered; secondly a method which observes the double-quantum transition and thirdly the other method which measures a change in population caused by the double-quantum pumping are considered, and finally the level shift due to the far-infrared input is considered. It is found that the third method of double-quantum pumping in which three waves are involved is the most sensitive. The minimum detectable power of order 10-6W/cm2 with the resolving time of about 10-6s is expected in detecting the maser output at the far-infrared which differs from the resonant frequency of the detector by as large as 10 GHz.

Slipped Capital Femoral Epiphysis

SEVERAL YEARS AGO, while visiting a well-known hospital in a large city, I saw on the operating schedule: Slipped Capital Femoral Epiphysis. When I inquired of my host regarding the type of operation used in this hospital for this condition, to my surprise he replied: Doctor, there are 17 orthopedic surgeons in this city and they use 17 different types of operation. This indicated to me that no orthopedic surgeon there had been able to develop an acceptable procedure for treating this condition which was convincingly better than any other so that it could be generally accepted as the method of treatment. I felt sorry for any patient in that hospital with this lesion because it seemed to me that his treatment was a matter of chance. Surely all of us know of this potentially crippling condition of childhood, the etiology of which appears to be related largely to growth.

Import Licensing in Pakistan

Pakistan's import trade in the private sector is regulated by an elaborate licensing system. It is complex in its structure and detailed in its operation. The structural complexity of the system arises from the simultaneous operation of different types of licences which seek to regulate the import sector in microscopic detail. It regulates the volume of imports, the composition of imports, and, in certain cases, even the sources of imports. This elaborate system is administered by the Chief Controller of Imports and Exports (CCI&E), in the Ministry of Commerce, who is the principal licensing authority in the country. His task is to assess import needs and then to allocate scarce foreign-exchange resources earmarked for the private sector. In arriving at his decisions he is guided, on the one hand, by the latest market intelligence reports regarding the price trends of imported commodities as the indicators of what the market actually needs, and on the other hand, by official views of what the market should need, and in what proportion, to conform to the broader scheme of ensuring an optimal allocation of domestic resources. The formulation of the semi-annual Import Policy, which is the sum-total of all these varied and complex decisions, is, therefore, a momentous undertaking, and occupies a central position in the broader strategy of economic planning.

TIC DOULOUREUX TREATED WITH NEW ANTICONVULSANT; EXPERIENCES WITH G 32883.

The numerous different types of operation described for trigeminal neuralgia are an indication of the therapeutic difficulties encountered with this disease. Even if several good methods of operation exist, they all have certain disadvantages that prevent them from enbeing ideal. The drugs reported as having any effect are few, and all of them either have proved toxic with long-term therapy or have had excessive secondary effects. A therapeutically practical method would seem to be to block the mechanism that gives rise to the attacks of pain, or—to put it another way—to find a means of blocking both normal and pathological transmission in synapses in the trigeminal area. At the same time, the drug used should be selective, so as not to have any marked effect on other cerebral functions, and it should be possible to give it over a long period. To be regarded as specific and safe, such a drug

Some Principles of the Production Control of Building Work: The Application of Queue Theory and of Simulation Techniques

IN recent years there has been a rapid development in production planning and control in a variety of industries. Among the methods which have contributed to this development are those of operational research, such as queue theory, sequencing theory and simulation. These methods have thrown light on the factors which influence the flow of production and have provided a basis for practical techniques for control. The Building Research Station has been studying the application of such methods to the control of production on building sites. The actual techniques used in the factory are mostly not applicable directly to building work, because of the different type of operations and the different conditions obtaining on the building site. However, it has proved possible to develop some of these methods so as to provide practical techniques which can be used both in research and in actual building work.

Effects of Rotatory and Valgus Malpositions on Blood Supply to the Femoral Head

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The Theory of Forward Exchange and Effects of Government Intervention on the Forward Exchange Market

THE THEORY OF FORWARD EXCHANGE badly needs a systematic reformulation. Traditionally, the emphasis has always been upon covered interest arbitrage, which forms the basis of the so-called interest parity theory of forward exchange.1 Modern economists, of course, recognize that operations other than interest arbitrage, such as hedging and speculation, also exert a determining influence upon the forward exchange rate,2 but a systematic theory of forward exchange which explains precisely how the interplay of all these different types of operation jointly determine the forward exchange rate and how the forward exchange market is linked to the spot exchange market still appears to be lacking. The purpose of this paper is to work out a more comprehensive and systematic theory of forward exchange, which would enable us better to understand the behavior of the forward exchange rate and to deduce the likely consequences of government intervention in the forward exchange market.

Natural Gas Supplies for Tomorrow

The control sought to be vested in the Federal Power Commission over the price received by the producer and gatherer of natural gas presents one of our most important contemporary problems. The issue, in so far as it affects the independent producer,' is now before the United State Supreme Court in the Phillips case (State of Wisconsin v. Federal Power Commission2). The issue as it affects natural gas companies has already been passed on in several cases, the soundness from the legal standpoint and wisdom of which are still being debated.3 The problem is a fundamental one in so far as natural gas supplies for tomorrow are concerned. The business of producing and gathering natural gas and selling it in or near the field is, under our American system, a private undertaking. The risks and hazards are so great that no one will undertake them if he is held to a return on his investment similar to that received by utility companies with altogether different types of operations and risks. Notwithstanding this, in the past decade through a series of encroachments on the part of the Federal Power Commission and by strained constructions given the Natural Gas Act by the courts, such a limitation on return or income would appear to be sought. As a basis for understanding the problem presented, it is necessary to describe briefly the nature of natural gas, the operations involved in producing and gathering it, and the competitive and risk-taking characteristics of gas exploration and production.

Hazards of lobotmy; study of two thousand operations.

Lobotomy for the relief of mental disorders and pain has become such a widely used procedure that a statistical analysis of a substantial number of cases seems worth while as a means of clarifying the dangers inherent in this type of procedure. This paper deals with my personal experience, at first with Watts 1 and later alone or with Williams, 2 over the 16 year period from 1936 to 1952. In this report no attempt is made to evaluate the different types of operations from the standpoint of effectiveness but only from that of safety. The question concerns not only operative or postoperative death but also later fatalities from causes not directly linked with surgery and also complications and sequelae of lobotomy that have impaired the social effectiveness of the patient. Finally, some figures are given to show the hazards of delay in treating patients by this method. The present

A comparison of the psychological effects of different types of operations on the frontal lobes.

Three years ago at the last International Congress of Psychology I reported on a preliminary investigation of personality changes after the usual standard prefrontal leucotomy. This investigation was carrried out on 20 neurotic patients before and three months after the operation performed by Mr. McKissock (McKissock, 1943). An extensive group of objective personality tests were chosen to define the factors of “Neuroticism” and “Introversion” as described by Eysenck (1947), which to all intents and purposes are equivalent to Cattell's (1950) factors C and F. In addition, the following intelligence tests were used: the Wechsler Scale, Porteus Mazes, and the proverbs from the Stanford Binet. The changes found provided us with some evidence in support of the hypothesis with which the investigation had been planned. This was that as a result of this type of incision in the frontal lobe there was a decrease in “Neuroticism,” a decrease in “Introversion” and a decrease in certain aspects of intelligence (Petrie, 1949a).Since then a further 50 patients have been examined before and after operations on the frontal lobes, bringing the total to 70. Most of these were severe neurotics attending the psychiatric department of Dr. Desmond Curran at St. George's Hospital, London. Only those changes will be referred to as an alteration in personality where the probability is less than one in twenty that they could have occurred by chance.

Protective Signaling

Protection of life and property may be secured by electrical signaling systems which have been developed to give protection against damage to property by fire, burglary, and other causes, and to supervise the activities of night watchmen and the operation of different types of mechanical equipment, and to perform other services. This paper consists of a general outline of the types of service available and the electrical systems for accomplishing them.

Protective signaling

Protection of life and property may be secured by electrical signaling systems which have been developed to give protection against damage to property by fire, burglary, and other causes, and to supervise the activities of night watchmen and the operation of different types of mechanical equipment, and to perform other services. This paper consists of a general outline of the types of service available and the electrical systems for accomplishing them.

Comparative End Results in the Intracapsular and Extracapsular Operations for the Removal of Senile Cataracts

Very prominent in the minds of most ophthalmologists performing opera­ tions for the removal of senile cataracts is the question as to whether the extra­ capsular (capsulotomy) or the intra­ capsular type of operation gives the more benefit to the greatest number of patients. Many of those who seek to improve their work find it difficult to formulate a definite opinion as to which is really the better operation for them. Most men do not operate on enough cataracts in a year to be able to perfect themselves in several different types of operations, or to try out the different methods of cataract extraction so as to be able to judge from personal experi­ ence which operation, gives them the best results. They must, therefore, en­ deavor to form an opinion from the ex­ perience of others as published in the various journals. The literature is flooded with reports of series of successful cataract extrac­ tions, running anywhere from a series of 30 to those of a thousand or more. These reports are almost always pub­ lished as part of a plea for the adoption of a certain type of operation, such as extraction after a certain type of capsu­ lotomy, or intracapsular extraction ac­ cording to Smith, or Stanculeanu, or Knapp*, and so on. All too frequently the end result as regards vision ob­ tained by the patients is entirely omitted from these reports, the me­ chanical operative result apparently being the important one in that particu­ lar author's opinion. Other writers merely state that were satisfac­ tory, but fail to distinguish whether this means satisfactory to the operator or to the patient. References to the obtained by competent operators with the other method are practically always entirely omitted, or, if mentioned, quote the statistics published several decades ago. That this is unfair and misleading is obvious to any impartial reader. For the antagonist of the intracapsular method of operating to quote the tre­ mendously high percentage of vitreous losses reported by the early followers of the Smith operation is as wrong as for the proponents of that method to quote articles published 20 to 30 years ago, giving the percentage of discissions needed after the capsulotomy operation in which the cystitome instead of the capsule forceps was used. Furthermore, even in the recent liter­ ature, one can hardly put much value on the opinion of an operator who re­ ports when he has sec­ ondary cataracts in over 30 percent of his cases*. This same holds for the intracapsular operator who regards a 24-percent vitreous loss as not bad. Again there is a tremendous differ­ ence of opinion as to what constitutes satisfactory visual results. Some auth­ ors* mean by good results anything as as 6/24, or 6/36 or even 20/150. One would hardly expect private pa­ tients in the United States to be satis­ fied with such dubious success. It seems to the author that in private practice in this country one can hardly qualify any as unless the vision is at least 6/12(20/40), or better. This, of course, brings the well-known fact that tests of vision can be greatly influ­ enced by any examiner who wishes to procure a series of very visual re­ sults. By increasing the amount of light on the test charts the number of 6/6 or better will be greatly increased, thus dressing up statistics. To compare one type of operation with another by quotations from the literature, we must compare the extra-

SURGICAL DISEASES OF THE COLON

The strikingly successful end-results following cooperative management of cases of toxic goiter, of complicated cases of peptic ulcer and of other types of diseases requiring specialized preoperative and post-operative attention find a decidedly suggestive parallel in the group management of surgical diseases of the colon. The combination of resources made available by isolation of patients with surgical lesions of the colon into a single division under the combined management of surgeon and clinician has brought results as striking, in our experience, in the short length of time in which it has been employed, as the results obtained from any segregated group of unusual cases. Not only has isolation of these patients afforded individualization, with better selection of cases for different types of operation, but collective management in the postoperative period has been equally invaluable. Colonic conditions are complicated; they extend over a long period before the patients who suffer from