Showing papers by "University of Minnesota published in 1969"

Nucleon-Nucleus Optical-Model Parameters, A > 40 , E 50 MeV

Abstract: Proton-nucleus and neutron-nucleus standard optical-model parameters are given that represent, quite well, much of the elastic scattering data in the range $Ag40$, $El50$ MeV. These parameters were determined by fitting simultaneously a large sample of the available proton data, and independently, a large sample of the available neutron data. Explicit energy- and isospin-dependent terms were included and their coefficients obtained directly from the data analysis. The results are shown to be consistent with the range and strength of the central and isospin components of the two-body interaction.

Late Results after Meniscectomy

Abstract: Two hundred thirteen patients with uncomplicated meniscus injuries were studied from ten to thirty years after their meniscectomy in order to determine the late effects of surgery. Delay of operation after injury did not affect the ultimate result. Patients less than twenty years old at the time of operation had fewer excellent and good results. The diagnosis is more difficult, and the benefit of meniscectomy is less certain, in women than in men. There was no difference in results between total and partial meniscectomy except in bucket-handle tears. Leaving the peripheral rim intact in uncomplicated bucket-handle tears produced the most excellent results. Persistence in a physical occupation or participation in non-contact sports seems not to alter the course after meniscectomy. It was usually, but not invariably, possible to correlate roentgenographic appearance with the clinical result. The meniscectomy site was readily apparent in ninety-four of 110 patients (85 per cent). Sixty-eight per cent of patients in our series had satisfactory clinical results, but only 45 per cent of men and 10 per cent of women had symptom-free knees.

The problem of dirichlet for quasilinear elliptic differential equations with many independent variables

Abstract: This paper is concerned with the existence of solutions of the Dirichlet problem for quasilinear elliptic partial differential equations of second order, the conclusions being in the form of necessary conditions and sufficient conditions for this problem to be solvable in a given domain with arbitrarily assigned smooth boundary data. A central position in the discussion is played by the concept of global barrier functions and by certain fundamental invariants of the equation. With the help of these invariants we are able to distinguish an important class of ‘ regularly elliptic5 equations which, as far as the Dirichlet problem is concerned, behave comparably to uniformly elliptic equations. For equations which are not regularly elliptic it is necessary to impose significant restrictions on the curvatures of the boundaries of the underlying domains in order for the Dirichlet problem to be generally solvable; the determination of the precise form of these restrictions constitutes a second primary aim of the paper. By maintaining a high level of generality throughout, we are able to treat as special examples the minimal surface equation, the equation for surfaces having prescribed mean curvature, and a number of other non-uniformly elliptic equations of classical interest.

On the Exact Covariance of Products of Random Variables

Abstract: For the general case of jointly distributed random variables x and y, Goodman [3] derives the exact variance of the product xy. For the special case where x and y are stochastically independent, he provides a simpler expression for the exact variance. We offer a weaker set of assumptions which suffices to yield the simpler expression. We then extend Goodman's analysis to present the exact covariance of two products xy and uv, and sketch several specializations and applications.

Effective lagrangians and field algebras with chiral symmetry.

Abstract: This paper reviews recent developments of effective Lagrangians and field algebras as means of treating chiral symmetry and partially conserved axial current (PCAC) for the study of elementary particle physics. The techniques employed are developed in considerable detail. As examples, we concentrate primarily on spin 0 and 1, linear and nonlinear realizations of $\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(2)$ and $\mathrm{SU}(3)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(3)$ and some of the significant predictions of the theory are derived. The paper contains an extensive discussion of an effective Lagrangian with nonets of real scalar, pseudoscalar, vector, and axial-vector mesons that illustrate the problems of broken $\mathrm{SU}(3)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(3)$.

Sensory conflict in judgments of spatial direction

Abstract: Artificial discrepancy was created between information about azimuth coming from different sense modalities. The resolution of this discrepancy was examined for the cases of vision and proprioception, proprioception and audition, and vision and audition. Vision biases proprioceptive and auditory judgments. Proprioception biases auditory judgments and has a small effect on visual judgments. The results suggest that the combinations of sense modalities do not behave as an integrated system and the data are interpreted as indicating that different processes are involved in the resolution of discrepant directional information from different pairs of modalities.

Sources of Agricultural Productivity Gap Among Selected Countries

Abstract: This study explores the causes of enormous agricultural productivity differences now existing among the developed and less developed countries. Factors are identified that determine the productivity gap, and their influences are gauged on the 1957–62 national aggregate data of 38 nations. Aggregate production functions are estimated on the cross-country data; and, with the estimates of production elasticities, the productivity differences between India and United States and between India and Japan are accounted for by conventional inputs (labor, land, fertilizer and machinery) and nonconventional inputs (education and research). The measured contributions of respective factors to the productivity differences provide a guideline for allocating development efforts in the less developed countries.

Fibrous xanthoma of synovium (giant-cell tumor of tendon sheath, pigmented nodular synovitis). A study of one hundred and eighteen cases.

Abstract: One hundred seventeen patients with 118 fibrous xanthomas of synovium were studied. Ninety-one of these xanthomas were in the fingers. The most common site was the dorsal surface of the distal joints of the index, long, ring, and little fingers. Fourteen tumors were found in the knee joint; four each, in the hand, wrist, and foot; and one tumor was in the hip joint. There was clinical or roentgenographic evidence that the joint from which the tumor arose or the joint nearest the tumor was damaged by traumatic or idiopathic degenerative joint disease in fifty-three patients. All of the tumors in this study were locally excised; 17 per cent recurred one or more times. All of the recurrences were in the fingers. From our material it could not be determined whether or not incomplete excision of the tumors accounted for these recurrences. Fibrous xanthoma, xanthoma due to disturbed systemic lipid metabolism, tumors of histiocytes, pigmented villonodular synovitis, and synovitis due to traumatic or idiopathic degenerative joint disease were compared with respect to some of their clinical and pathological characteristics.

Induction of drug metabolism. I. Differences in the mechanisms by which polycyclic hydrocarbons and phenobarbital produce their inductive effects on microsomal N-demethylating systems.

Abstract: The administration of 3,4-benzpyrene, 3-methylcholanthrene, or phenobarbital to male rats stimulated the N-demethylation of 3-methyl-4-methylaminoazobenzene (3-MMAB) by hepatic microsomes, but only phenobarbital stimulated the N-demethylation of ethylmorphine. Simultaneous administration of maximum stimulatory doses of 3-methylcholanthrene and phenobarbital resulted in additive stimulation of N-demethylation of 3-MMAB, whereas similar treatment with 3,4-benzpyrene and 3-methylcholanthrene did not stimulate 3-MMAB N-demethylation beyond that observed when either was administered singly. Thioacetamide prevented increases in N-demethylation resulting from phenobarbital administration, but had little effect on increased drug metabolism resulting from 3-methylcholanthrene administration. It was concluded that 3,4-benzpyrene and 3-methylcholanthrene stimulate hepatic microsomal drug-metabolizing activity by the same mechanism and that phenobarbital stimulates drug metabolism through a different mechanism. During phenobarbital administration parallel increases were observed in the N-demethylase activities and in the cytochrome P-450 content of microsomes; when phenobarbital was discontinued, microsomal N-demethylase activities and cytochrome P-450 content decreased in a parallel manner. Thioacetamide, administered alone, caused concomitant decreases in N-demethylase activities and cytochrome P-450 content. When given with phenobarbital, thioacetamide prevented the usual increases in N-demethylase activities and in cytochrome P-450 content seen when phenobarbital is administered. Polycyclic hydrocarbons caused an increase in microsomal P-450 content and in 3-MMAB N-demethylase activity, but the increases were not parallel. No increase in ethylmorphine N-demethylase activity occurred even though the content of microsomal hemoprotein was elevated. These studies suggested either that cytochrome P-450 is not rate-limiting in the over-all ethylmorphine N-demethylation reaction or that the administration of polycyclic hydrocarbons causes the synthesis of a microsomal hemoprotein different from that which was present initially in that it is capable of participating in the N-demethylation of 3-MMAB, but not of ethylmorphine.

Implantable electronic stimulator electrode and method

Abstract: An apparatus for implantation in the body to locally stimulate a mass of electrically excitable tissue without stimulating nearby tissue structures, and the method of so stimulating the tissue is described The apparatus includes a plurality of electrodes, each of the electrodes including a pair of conductors for carrying signals of positive and negative polarity, each of said conductors having a plurality of electrically conductive coupling points for coupling to the mass of tissue Apparatus is also described for providing timed sequenced electrical impulses to the plurality of electrodes so that only one of the electrodes has a voltage applied between its input terminals at any given time An insulating backing placed between the electrodes and tissue structures surrounding the implanted stimulator for eliminating undesirable secondary tissue stimulation is also described The method of applying controlled time-spaced electrical impulses to a mass of electrically excitable tissue structure for causing stimulation of that tissue structure is also described

The rhetoric of confrontation

Abstract: (1969). The rhetoric of confrontation. Quarterly Journal of Speech: Vol. 55, No. 1, pp. 1-8.

Cystic Medial Necrosis of the Ascending Aorta in Relation to Age and Hypertension

Abstract: The presence of cystic medial necrosis in the human ascending thoracic aorta was determined by histologic examination in a series of 250 necropsies. Cases of Marfan's syndrome, idiopathic dilatation of the aorta and dissecting aneurysm were not included. The severity of lesions of cystic medial necrosis were graded on the basis of 1 to 4 according to the amount of basophilic ground substance and fragmentation of elastic tissue. In most positive cases the lesion was of minimal (grade 1 or 2) severity. The incidence of cystic medial necrosis increased progressively from 10 percent in the first two decades of age to 60 and 64 percent in the seventh and eighth decades, respectively. Using the Fisher probability test, this difference is highly significant (P < 0.01). Among hypertensive subjects, the incidence of cystic medial necrosis was consistently higher than in normotensive subjects of comparable ages. Using the chi square test by decades and “all together”, this difference could easily be due to chance alone (P = 0.36 → 0.94).

In-Situ Stress Determination At Great Depth By Means Of Hydraulic Fracturing

Abstract: One of the main functions of rock mechanics research has been to find ways of determining in situ stresses. Most methods usually employ some instrumentation for the purpose of measuring hole deformation. The method of hydraulic fracturing has been suggested, because it has been shown that the recorded pressures can be theoretically related to magnitudes of the principal in situ stresses; the orientation of the fracture can often be used to determine the direction of the principal stresses. The advantage of hydraulic fracturing over the present in situ stress determination methods is simplicity: no sophisticated instrumentation is required inside the borehole; hence, the stresses can be measured at any depth. If the formation is impermeable to the fracturing fluid, no elastic constants of the rock are required in calculating the stresses, a factor that not only simplifies the problem, but renders the results more reliable. The theoretical considerations are discussed. A laboratory experimental program was undertaken to verify some of the assumptions and results stated in the theoretical section. The equipment is described. (19 refs.)

The paradox of myocardial ischemia and necrosis in young women with normal coronary anteriograms. Relation to abnormal hemoglobin-oxygen dissociation.

Abstract: A double-blind study was carried out on 15 premenopausal women under 40 years of age who showed objective evidence of myocardial ischemia or necrosis as demonstrated by electrocardiogram or enzyme studies, or both. In each, selective coronary arteriography was normal. Three women later died with single or multiple subendocardial infarcts. None had disease of the large or small coronary arteries. None had a predisposing cause of premature coronary artery disease, except that 8 smoked cigarettes and 4 were obese. Abnormal hemoglobin-oxygen dissociation was found in 14 of the 15 women with myocardial ischemia or necrosis. Among 3 who discontinued cigarette smoking, the anomalous dissociation returned to normal within one month of cessation of cigarettes. In the other 5 it remained anomalous. Fifteen age-matched control women were also studied by double-blind technic. Abnormal dissociation was found in the 1 control subject who smoked (more than 12 cigarettes daily for more than 15 years). Selective coronary arteriograms were not performed among women in the control group. The strong correlation between the empiric observation of abnormal hemoglobin-oxygen dissociation and the presence of myocardial ischemia and necrosis with normal coronary arteriograms suggests that there may be a relation. This may be true in view of the high oxygen demands of the myocardium (especially the subendocardium). It is possible that inefficient or slow release of oxygen by hemoglobin could contribute to myocardial ischemia or necrosis. Alternatively, the hemoglobin-oxygen affinity changes may be secondary “stress phenomena.” Electrocardiographic abnormalities occurring at rest during forced hyperventilation appear to aid in predicting the laboratory abnormality. Propranolol is often effective in treating this condition.

Clinical and pathologic features of postinfarction cardiac rupture.

Abstract: In a 15 year period 106 instances of myocardial rupture after myocardial infarction were observed at autopsy, an incidence of 8.6 per cent of fatal acute myocardial infarcts. This complication occurred most frequently in the seventh and eighth decades and was slightly more common in women. Clinically, rupture occurred most frequently during the first week after infarction. Historical evidence of previous coronary artery disease was uncommon. Hypertension had been present in 70 percent of the patients, but it persisted after the infarct in less than a third. Pathogenetic factors were sought in the clinical aspects of the patients. No definite role could be ascribed to anticoagulant or sympathomimetic drugs or digitalis. Physical activity after infarction may be a predisposing factor in some instances. Sudden death without antecedent change in symptoms most often occurred. Cardiac tamponade or vascular collapse was documented in a few instances prior to death. In most instances no physical findings, laboratory tests, or electrocardiographic features that indicated cardiac rupture could be ascertained. Based on histologie data, 90 per cent of the ruptures occurred during the first two weeks after infarction, at an average time of five days; 22 per cent were in the first 24 hours, and 69 per cent were in the first week. All of the infarcts were transmural and involved large areas of the left ventricle. Ruptures presented as distinct tears (79 per cent) or large areas of hemorrhagic dissection (9 per cent), or both (12 per cent). The most common site of rupture was through the anterior wall of the left ventricle; commonly, ruptures were near the septum or near the base of papillary muscle. The areas of rupture were more common in the basal two thirds of the ventricle than in the apical portion. The ruptures varied greatly in size. Most were situated within the area of infarction rather than at the junction between the infarcted and the normal myocardium. Unusual accumulations of polymorphonuclear leukocytes were not found in most specimens. Most hearts had severe coronary artery disease, but myocardial scarring was present in only a fourth. Cardiac hypertrophy was usually present. The amount of hemopericardium varied widely and was the apparent mechanism responsible for death in some patients. Mural hemorrhage, hypertension, degree of polymorphonuclear infiltration, degree of myocardial fibrosis and location of the infarct may all be of pathogenetic significance in post-infarction rupture in different situations, but these considerations did not have universal applicability. The only common morphologic features among the infarcts that ruptured were their large size and transmural extent. The major pathogenetic considerations probably are loss of tensile strength of the infarcted segment, increased tension in this area, and, in some cases, divergent vector forces.

The Moments of Log-Weibull Order Statistics

Abstract: Let X 1n ≤ X 2n ≤,…, ≤ Xnn be the order statistics of a random sample of size n. For any integrable function g(x) define E(i, n) = E(g(X in )) and M(n) = E(1, n) = E(g(X 1n )). A number of formulae expressing E(i, n) in terms of M(j), j ≤ n, are developed. For example, These results are applied to obtain the means and variances of the order statistics of a log-Weibull distribution (F(z) = 1 – exp (− exp x)). Tables of these means and variances are given for 1 ≤ i ≤ n, n = 1 (1) 50 (5) 100. The computations were made using a set of 100 decimal place logarithms of integers. Examples of the use of these tables in obtaining weighted least squares estimates from censored samples from a Weibull distribution are also given.