Showing papers by "University of Kentucky published in 1973"

Hydrodynamic Prediction of Peak Pool-boiling Heat Fluxes from Finite Bodies

Abstract: Previous theoretical models are considered, giving attention to the original formulation proposed by Zuber (1959), an infinite horizontal flat plate, a horizontal cylinder, and a sphere. Some general features of any hydrodynamic prediction are inferred by examining the characteristics of the models. It is found possible to eliminate the need for observed values of the vapor-blanket thickness. The concepts obtained are utilized in the derivation of expressions for the prediction of the peak pool-boiling heat flux in the case of some new configurations.

A revised simplex method for linear multiple objective programs

Abstract: For linear multiple-objective problems, a necessary and sufficient condition for a point to be efficient is employed in the development of a revised simplex algorithm for the enumeration of the set of efficient extreme points. Five options within this algorithm were tested on a variety of problems. Results of these tests provide indications for effective use of the algorithm.

Studies of a Class of Covariance Structure Models

Abstract: This article demonstrates the usefulness of analysis of covariance structure procedures for estimating variance components under more general assumptions than are provided in the typical mixed-model analysis of variance. A sequence of eight models is presented based on varying degrees of restrictive assumptions. Maximum likelihood procedures are employed in the estimation of the parameters of the models. The procedures are applied to simulated data and to an empirical example which shows the necessity of the more general assumptions.

Peak Pool Boiling Heat-Flux Measurements on Finite Horizontal Flat Plates

Abstract: Boiling and Phose Change Laboratory, Mechanical Engineering Department, University of Kentucky, Lexington, Ky. Experimental data obtained at both earth-normal and elevated gravity, in a variety of organic liquids and water, are used to verify the hydrodynamic theory for the peak pool boiling heat flux on flat plates. A modification of Zuber' s formula, which gives a 14 percent higher peak heat flux, is verified as long as the flat plate is more than three Taylor wavelengths across. For smaller heaters, the hydrodynamic theory requires a wide variation in heat flux owing to discontinuities in the number of escaping jets. Data for smaller plates bear out this predicted variation with heat fluxes that range between 40 percent and 235 percent of Zuber' s predicted value. Finally, a method is suggested for augmenting the peak heat flux on large heaters, and shown experimentally to be viable.

Size and Foreign Policy Behavior: A Test of Two Models

Abstract: The categorization of states according to size has long been a part of world politics. Rothstein notes, for example, that the formalization of the categories of great and small powers occurred as a result of the signing of the Treaty of Chaumont in 1817. Recently, the concept of size has received an increasing amount of attention as a factor affecting foreign policy. One manifestation of this is the renewed interest in die foreign policy behavior of small states. In his pre-theory of foreign policy, Rosenau includes size as one of three “genotypic” variables assumed to exert a major influence on foreign policy. In addition, empirical studies have shown size to be an important factor underlying variations in the international behavior of nation-states.

A clinical system for scoring a patient's oral hygiene performance.

Abstract: A need was recognized for a recording system to evaluate a patient’s oral hygiene performance. In a system developed to satisfy five requirements, plaque retention and bleeding points are used as the criteria for evaluation. Because the performance of the patient can be measured, parameters for an effective level of oral hygiene can be established.

The Gas of Long Rods as a Model for Lyotropic Liquid Crystals

Abstract: The microscopic theories which have been proposed for lyotropic liquid crystals are studied, in particular in connection with the model gas of hard rods. For sufficiently long rods most theories are equivalent to that of Onsager; for shorter rods no theory seems to have a very good claim to accuracy. The theory of Flory is shown to be untrustworthy. A series of experimental tests is proposed which would allow determination of the coefficients of the Onsager expansion; available experimental data are reviewed.

Factor-Xa inactivation by antithrombin. 3. Evidence for biological stabilization of factor Xa by factor V-phospholipid complex.

Abstract: Summary. The inactivation of the procoagulant activity of bovine factor Xa by antiproteinase present in antithrombin III preparation follows the pseudo-first-order kinetics with respect to factor Xa. The rate of inactivation is devoid of the dimension of factor Xa concentration when antiproteinase in excess is held constant. In the presence of physiological concentrations of factor V, phospholipids and ionic calcium, the affinity of factor Xa for antithrombin III drastically decreases, and the half-life of the enzyme is very significantly prolonged. This biological stabilization of factor Xa requires the presence of all three substances: factor V, phospholipid and calcium. However, it is quantitatively dictated only by factor V concentrations. Calcium ions and phospholipid required for factor Xa protection from inactivation by antithrombin III have a rather low optimum concentration range, beyond which the original fast rate of inactivation tends to be restored. A direct interaction between antithrombin III and factor V or phospholipid was not found. Thus binding of factor V mediated by phospholipid and calcium ions, which brings about the increase in factor Xa proteolytic activity, also decreases the susceptibility of this enzyme to a biological inactivator in blood.

Extended hydrodynamic theory of the peak and minimum pool boiling heat fluxes

Abstract: The hydrodynamic theory of the extreme pool boiling heat fluxes is expanded to embrace a variety of problems that have not previously been analyzed. These problems include the prediction of the peak heat flux on a variety of finite heaters, the influence of viscosity on the Taylor and Helmoltz instability mechanisms with application to film boiling and to the peak heat flux in viscous liquids, the formalization of the analogy between high-current-density electrolysis and boiling, and the description of boiling in the low-gravity limit. The predictions are verified with a large number of new data.

Conditioning of successive adaptive responses to the initial effects of drugs.

Abstract: Data in the literature indicate that conditioned responses (CRs) generated by repeated pairing of conditional stimulus (CS) with administration of a neurotropic drug may resemble its unconditional effects or they may be opposite in direction; furthermore, the CRs may change as such pairings are continued. In explanation, it is hypothesized that as in conditioning of physiological reflexes, a CS repeatedly paired with administration of a neurotropic drug eventually comes to activate central“processing” events that are evoked by the“stimulus” properties of the drug,i.e., the effects of the drug at receptor sites inside or outside the pia mater which lie in the afferent arms of“reflex” neural circuits; or, the CS comes to activate central processing events that are evoked by centripetal feedback responses to the effects of the drug at receptor sites in the processing or efferent arms of reflex neural circuits. Depending on the receptor site action of the drug, the conditioned autonomic and/or neuromuscular responses that are observed may be in the same direction as, or opposite in direction to the unconditioned effects of the drug. With continued pairings of CS and drug, the unconditioned processing events evoked by the stimulus properties of the drug, and hence the CRs also, change in consequence of compensatory (sometimes“overshooting”) biochemical alterations proximal to the receptor site of action of the drug, induced by negative or positive neuronal feedback mechanisms. These concepts are utilized in a theory of opiate addiction and relapse.

Deformation mechanisms in commercial Ti (0.5 at. pct oineq) at intermediate and high temperatures (0.3 - 0.6 tinm)

Abstract: The plastic flow of the commercial titanium material Ti-50A (0.5 at. pct Oeq) of 22 μm grain size was investigated over the temperature range of 600 to 1150 structure) and strain rates of 3 x 10-5 to 3 x 10-2 per s employing both constant strain rate and strain rate cycling tests. Dynamic strain aging occurred in the temperature range of 600 to 850 (0.31 to 0.44Tm) with an activation energy of 50 kcal per mole derived from the start of serrations in the stress-strain curves, maxima in strain hardening and minima in ductility. This value is in accord with that for the diffusion of oxygen in titanium. At temperatures above 850 (0.46 to 0.59Tm) the data were very well represented by Weertman’s glide and climb high temperature creep mechanism, giving eskT/Dμb= 1.1 x 106 (σ/μ)4.55 withD = 1.0 x exp (- 57,800/RT). The value of 57.8 kcal per mole is in accord with available self-diffusion data for titanium.

Mammary duct proliferation in the elderly. A histopathologic study.

Abstract: Both breasts of women over 70 years of age dying from causes other than mammary cancer were studied microscopically at autopsy by multiple step sections. Intense focal intraductal proliferative activity was characteristic of almost half of the breasts of women in this age group. Proliferative intraductal changes tended to be bilateral and were frequently associated with adenosis and intraductal papillomas. Four cases (5.7%) showed intraductal carcinoma, and, in one of these (1.4%), there was a focus of microinvasion. All four cases showed both benign and atypical hyperplastic lesions in other areas of the breast. It is concluded that occult infiltrating breast carcinoma, unlike occult prostatic carcinoma, is an infrequent lesion in the elderly. Intraductal carcinoma, while somewhat more common, is unlikely to eventuate in clinical malignancy within the life span of these patients. Intraductal hyperplasia appears to be a common finding in the elderly and need not be viewed with alarm.

Postnatal Changes in Rat Ventricular Function

Abstract: Experiments were designed to assess the intrinsic changes in myocardial function with age and to determine the role of increasing left ventricular mass in this process. Isometric ventricular pressure-volume curves and length-tension curves were measured in isolated perfused rat hearts of different ages and masses. Incremental tension, peak active tension, and peak passive tension were less for 10-day-old hearts than they were for older hearts subjected to proportionately equal increases in length. At resting length, peak active tension developed by hearts at least 16 days old was 78% higher than that developed by 10-day-old hearts, and peak passive tension was 133% higher. There was no significant difference between 16-day-old rats and older rats. Thus, by the sixteenth postnatal day, the heart had developed functional maturity. These functional changes appeared to be related to age rather than to left ventricular mass. Histological studies of the left ventricle showed that, at birth, the myofibrils were disoriented with a high ratio of nonmyofibrillar elements to myofibrillar elements. Within 16-20 days after birth, the structural organization and the ratio of nonmyofibrillar elements to myofibrillar elements were similar to the organization and the ratio found in an adult. Thus a direct relationship existed between the functional properties and the anatomical development of the myocardium. Mass per se was not the sole factor that contributed to improved myocardial function with age.

Heritability of the Carabelli Cusp in Twins

Abstract: The study of the Carabelli trait among 199 monozygotic and dizygotic twin pairs failed to demonstrate a high degree of heritability. Analyses of antimere differences in individuals indicated a lack of mirroring and no sexual dimorphism. Monozygotic twin pairs exhibited a higher concordance rate for corresponding tooth comparisons than dizygotic twin pairs.

Possible role of 6-hydroxymethylbenzo[a]pyrene as a proximate carcinogen of benzo[a]pyrene and 6-methylbenzo[a]pyrene†

Abstract: Benzo[a]pyrene (B[a]P) and 6-methylbenzo[a]pyrene ( 6-MeB[a]P) are metabolized by fortified rat-liver homogenates to a number of metabolites including one which is indistinguishable from 6-hydroxymethylbenzo[a]pyrene (6–OHMeB[a]P) by either thin-layer chromatography or ultra-violet absorption spectra. This compound is a potent carcinogen when administered by subcutaneous injection to rats. These observations are in accord with the hypothesis that methylation or hydroxymethylation is one of the first steps in metabolic activation of carcinogenic polycyclic hydrocarbons.

On the uniqueness of the topological degree

Abstract: In recent years there has been considerable success in extending the theory of topological degree for mappings in infinite-dimensional spaces beyond the compact perturbations of the identity considered by Leray and Schauder [223. Perturbation of the identity by weakly continuous maps [-21, 1], inclusion of a term corresponding to a contraction or to a k-set-contraction [10, 17, 30, 23, replacement of the identity by a more general homeomorphism or a quite general local diffeomorphism [5, 6, 13, 14, 153, degrees dependent on a representation [6, 73, possibly multivalued, and defined in terms of an approximation scheme [8, 9, 36] have provided many \"degree theories\" with limited knowledge of their mutual relation. It is not yet clear to which extent these notions preserve the various properties of the classical Brouwer degree, an extreme example being the loss of homotopy invariance in one case ([123, see w below). In addition, even in the finite-dimensional case, the analytic definitions of the Brouwer degree by Nagumo [23], based on Sard's theorem, and by Heinz [18], based on the Kronecker integral, omit a discussion of uniqueness, though it is mentioned in [24] that this may be proved by simplicial approximation. For the Leray-Schauder degree, this matter is usually referred to O'Neill's article [27], based on the fixed point index as introduced via cohomology theory.

Parameters of Deposit Contracts in the Modification of Smoking

Abstract: Contingency contracting wherein the reinforcer was the return of some of S’s money deposit effectively eliminated smoking in 2 groups of smokers for the duration of the contract, compared to 2 groups of Ss on a noncontingent money deposit contract. A 2-week maintenance period, part of the contract for 1 of each pair of groups, failed to have any effect. While 3- and 6-month follow-ups indicated substantial relapses in all groups, it was found that low frequency smokers, particularly those in the contingent groups, showed a significant tendency to remain abstinent. Results of the study were discussed in relation to the contracting technique and the general area of behavior modification.

Ultrastructural study of penetration of maize leaves by Colletotrichum graminicola

Abstract: When maize leaves are inoculated with conidia of Colletotrichum graminicola the uninucleate, single-celled spores swell and undergo mitosis. In each spore a septum forms between the daughter nuclei and one cell of the resulting two-celled structure germinates to produce an appressorium with an electron-dense outer cell wall. Prior to penetration a new, inner, electron-lucent wall forms around the basal portion of the appressorium. During penetration, which occurs 6 to 9 h after inoculation, the outer dense wall of the appressorium disappears, without evidence of mechanical disruption, in the area of the developing infection peg. At all stages of infection the infection peg and the hypha which develops from it are enveloped by a distinctive, electron-lucent cell wall which is continuous with the inner wall of the appressorium. During penetration only the cuticular layers of the host cell wall are depressed inward. Dense host reaction products (papillae) are formed and the plasma membranes are disrupted before cell walls are completely penetrated and also in cells adjacent to those invaded by the fungus. The infection process is completed within 12 h by the formation of a septum between the appressorium and the swollen infection hypha.

On Non-Negative Quadratic Unbiased Estimation of Variance Components

Abstract: Linear combinations of variance components for which there exist unbiased, non-negative quadratic estimators are characterized. It is shown that the ‘error’ component in ANOVA models is the only single component which can be so estimated.

An integral equation formulation of three dimensional anisotropic elastostatic boundary value problems

Abstract: An approximate solution capability is developed to handle three dimensional anisotropic elastostatic boundary value problems. The method depends crucially on the existence and explicit definition of a fundamental solution to the governing partial differential equations. The construction of this solution for the anisotropic elastostatic problem is presented as is the derivation of the expression for the surface tractions necessary to maintain the fundamental solution in a bounded region. After the fundamental solution and its associated surface tractions are determined, a real variable boundary integral formula is generated which can be solved numerically for the unknown surface tractions and displacements in a well-posed boundary value problem. Once all boundary quantities are known, the field solution is given by a Somigliana type integral formula. Techniques for numerically solving the integral equations are discussed.