Non-homogeneous Type Research Articles

Oral leukoplakia, with emphasis on malignant transformation: A follow-up study of 46 patients

A review of oral leukoplakia, based on data from the literature and experience with 84 patients is presented. The leukoplakic lesions of 3 patients developed malignant transformation within an average period of 5 years. All three patients were elderly women with idiopathic leukoplakia, in two cases of the homogeneous and in one case of the non-homogeneous type. The initial biopsy of the former two patients showed only hyperorthokeratosis without epithelial dysplasia. In the first biopsy of the third patient epithelial dysplasia was recorded. One of the patients finally died of widespread metastases. The other two have been treated surgically and are still alive.

The treatment of nonhomogeneous Dirichlet boundary conditions by thep-version of the finite element method

The paper addresses the problem of the implementation of nonhomogeneous essential Dirichlet type boundary conditions in thep-version of the finite element method.

Effect of material nonhomogeneity on stress distribution in the vicinity of a thin elastic inclusion

A problem of a matrix of exponentially nonhomogeneous material has been discussed in a case a thin elastic inclusion of a similar type of nonhomogeneity. A stress function for elastic solids of exponential non-homogeneity varying with x and y has been derived.

Yeast species and biotypes associated with oral leukoplakia and lichen planus

Of 36 patients, 17 had oral leukoplakia, including homogeneous and nonhomogeneous types, and 19 had reticular lesions of oral lichen planus. A sample of yeast flora in each patient was taken from the pathologic lesion as well as from normal-appearing mucosa. The isolated yeasts were identified according to species level, and identification was extended beyond the species level for one species, Candida albicans, to reveal the biotype by means of the Odds and Abbott procedure comprising tests for acid and salt tolerance, proteinase production, resistance to 5-fluorocytosine and safranine, and assimilation of urea, sorbose, and citrate. Yeasts were present in the lesions of 82% of leukoplakia patients, compared to 37% of lichen planus patients, a frequency of yeasts corresponding to that in healthy adults. C. albicans was the dominating species in lesions of both diseases, constituting 82% of all yeasts in the leukoplakia lesions. In addition, the following species were identified: Canadia tropicalis, Candida pintolopesii, Torulopsis glabrata, and Saccharomyces cerevisiae. Eighteen biotypes of C. albicans were encountered, the most frequently occurring biotypes being 355 and 177. Differences between C. albicans biotypes isolated from pathologic and normal mucosa were encountered in five of eleven leukoplakia patients and in one of three lichen planus patients. This indicates that the oral cavity comprises several ecologic niches for yeasts. As nonhomogeneous leukoplakias are more likely to develop into carcinoma than are homogeneous leukoplakias, it is interesting to note that the C. albicans biotypes isolated from nodular lesions (one type of nonhomogeneous leukoplakia)—biotypes 145, 175, and 575—rarely occur. The observation might indicate a possible causal role of some C. albicans biotypes in transformation of leukoplakia into carcinoma.

Analysis and interpretation of single‐well tracer tests in stratified aquifers

This study deals with the definition and measurement of the dispersive properties of a stratified aquifer based on the single‐well tracer test. Knowledge of such dispersive properties are of fundamental importance to the evaluation, analysis, and simulation of contaminant migration in groundwater, a subject of great interest in recent years. In the single‐well test, tracer is pumped into the formation for a period of time and then pumped out. Concentration data are obtained from the injection‐withdrawal well and from one or more sampling‐observation wells which may be multilevel. Our analysis of such a test is based on a Lagrangian‐Eulerian numerical model which considers the depth‐dependent advection in the radial direction and local hydrodynamic dispersion in the vertical and radial directions. Results show that the movement of an injected tracer in a stratified aquifer may be accurately simulated without resorting to the use of a scale‐dependent, full aquifer dispersivity if the flow field is known in sufficient detail. When the advection process is simulated accurately, the values of local dispersivity will be small, constant, and on the order of those measured in the field or laboratory at individual levels in the aquifer. The full‐aquifer breakthrough curves measured in observation wells in a single‐well test in a stratified aquifer are determined by the hydraulic conductivity profile in the region between the injection‐withdrawal well and the observation well if the travel distance between these wells is typical of most test geometries. However, the relative concentration versus time data recorded at the injection‐withdrawal well during the withdrawal phase is primarily a measure of mixing in the aquifer due to local dispersion which has taken place during the experiment. The amount of mixing will depend on both the hydraulic conductivity distribution in the aquifer and the size of the experiment. As the experiment scale increases, the effects of local vertical dispersion will become larger compared to the effects of local radial dispersion. Local vertical dispersion will cause a solute traveling in a high‐conductivity layer in an aquifer to migrate into adjacent low‐conductivity layers where its movement will be relatively slow in comparison. In the initial design of a tracer test it is important to have some idea of the type of nonhomogeneity with which one is dealing. More information of a broad nature concerning the types or classifications of nonhomogeneities that exist in natural aquifers would be very useful. Future research in this area is needed.

A simple approximate method for the solution of the Helmholtz equation in the case of rectangular, non-homogeneous domains

The dynamic behavior of non-homogeneous continuous media is of interest in many fields, from geophysics to everyday mechanical engineering systems and especially in bioengineering. Discontinuous types of non-homogeneities are considered in this paper and it is shown that the Ritz method is convenient for this complicated type of structural element.

Mindlin Plate Analysis by Segmentation Method

A method for the numerical analysis of rectangular plates based on Mindlin's theory is presented. Any two opposite edges are assumed to be simply supported in the present analysis. A variety of boundary conditions including the mixed and the nonhomogeneous types can be specified along either of the remaining two opposite edges. Numerical results are presented for four examples. The present results clearly show the discrepancies in the results of the usual thin plate theory. Some of the problems associated with the use of the thin plate theory based on Kirchhoff's assumptions are clarified. Finally it is shown that the present segmentation method which is based on the numerical integration of the governing equation system is efficient, economical, reliable, and very accurate in such applications.

Nonhomogeneous Stochastic Automata

In this note we consider a nonhomogeneous Markov chain type stochastic automaton which is a generalization of Bartoszyński’s stochastic automaton. The latter is a generalization of the Pawlak’s known machine in a stochastic direction. By nonhomogeneous stochastic automaton we mean a system ⟨ T, α, {A(n), n ⩾ 1}⟩, where T is a finite nonempty set, α, is an initial distribution on T, and {A(n), n ⩾ 1} is a matrix sequence whose every element is a stochastic matrix called a transition probability matrix. If A(n) = A for all n ⩾ 1, then we obtain Bartoszyński’s automaton. The sequence (ti0, ti1, …), tij ∈ T, j = 0, 1, 2, … is called a word of automata if α(ti0) > 0 and A(k)(tik-1, tik) > 0 for every k ⩾ 1. The goal of this note is to give necessary and sufficient conditions for the existence of an extension and a shrinkage of the automata under consideration. These problems for T, A were considered for the first time by Bartoszyński. The shrinkage problem deals with the existence of a stochastic automaton which generates only all sequences of states of T which are simultaneously generated by two given automata while the extension problem treats of the existence of a stochastic automaton which generates all sequences of states of which are generated by at least one of two given automata. Moreover, we introduce some new notions: attainable state, concordance of automata in a wide and a narrow sense, which help us to solve the problems mentioned above.

Numerical analysis of elastic plates with two opposite simply supported ends by segmentation method

A method for the numerical analysis of elastic plates with two opposite simply supported ends is presented. A variety of boundary conditions including the mixed and the nonhomogeneous types can be prescribed along either of the remaining two opposite edges. Numerical results are presented for the three examples. Based on the comparisons made with the results available elsewhere, it is concluded that the present method is efficient, economical, reliable and very accurate.

土佐湾沿岸域のシラス漁業における漁獲量の日変動

The daily catch of shirasu fishery in the coastal region of the Tosa Bay fluctuates irregularly day by day, while the seasonal change of species or size composition in catch is almost stationary every year. As the histogram of C(t) which is the cubic root of daily catch shows some normal distribution, time series analysis was carried out depending upon the stantionary and ergodic property of C(t). According to the inspections, it is inferred that C(t) fluctuation is based on the long term period of a month or more and is modified by some characteristic period of a few days or a week. And under the assumption that C(t) may be determined by the abunadance of fishing resource and the complex system which is composed of some factors and is specific to the fishery ground, the author attempted to analyze C(t) fluctuation by considering the ordinary differental equation of nonhomogeneous type. It was found that the two comparative spectra which are S(ƒ) that is got from the real C(t) fluctuatoon and Sc(ƒ) from this system analysis are in close correspondence.

Nonoscillation of arbitrary order retarded differential equations of non-homogeneous type

The object of the present paper is to study the delay differential equation of arbitrary order namely y(n)(t) + a(t)yτ(t) = f(t), n≥2 (an integer) and prove a nonoscillation theorem under the general situation in which a(t) and f(t) are allowed to oscillate arbitrarily often on some positive half real line. This is accomplished by way of two differential inequalities of nth order.

Analysis of centrifugal stresses in anisotropic viscoelastic cylinder.

HE stress analysis for anisotropic viscoelastic materials has become the subject of increasing concern in the past few years. The ever increasing use of composites and oriented plastics as structural members has made it necessary to study the effect of anisotropy as well as viscoelasticity on the performance of these components. Problems in linear isotropic viscoelasticity have been analyzed by many authors, such as Lee, 1 Hilton,2 and Bland,3 under various loading conditions. However, similar attempts in the analysis of anisotropic viscoelasticity have been frustrating because of the difficulties faced in the use of Laplace transform, particularly in the inversion of solutions. As a result, even the simple problems which can be solved explicitly, become important in understanding the interaction of anisotropy and the viscoelastic behavior of materials.4 ~ 6 In this paper, some elementary solutions of stress analysis problems for an anisotropic viscoelastic cylinder are given. Specifically, analysis for a long hollow cylinder, rotating about its axis, is considered. In the course of the analysis, the constitutive equations of the theory of infinitesimal viscoelasticity exhibiting a general anisotropic behavior are assumed. These are expressed in terms of different time-dependent modulus functions. A particular type of spacial nonhomogeneity, where the material moduli are assumed to be representable as a production of functions of time and coordinates, is considered. Through the application of integral (Laplace) transform the problem is then solved. Although the analysis is made for a general linear viscoelastic medium, for simplicity, numerical results are presented for a material having simple viscoelastic behavior. Anisotropic Viscoelasticity The basic problem in quasi-static linear viscoelastic stress analysis is to determine a stress field atj(xk, t) and the displacement field wf(xfc, t) as functions of space variables xk and time t. The governing equilibrium equations, which are independent of material constitution, are the displacement-strain relations and the principles of linear momentum and moment of momentum. They are in the usual notation

Transient rotary shear waves in nonhomogeneous viscoelastic media

Propagation of axisymmetrical rotary shear waves in nonhomogeneous viscoelastic media with a cylindrical hole is studied. Nonhomogeneities are assumed to depend on the radial distance from the axis of the hole. By means of the theory of the propagating surfaces of discontinuities, the solutions for the shear stress and particle velocity are expanded as Taylor series about the time of arrival of the wave front. Both stress-prescribed and velocity-prescribed boundary conditions are considered. The corresponding elastic problem is investigated as a special case; and, for certain types of nonhomogeneity, explicit solutions are presented and compared with the solutions obtained by the Laplace transform technique.

Paper chromatography of metal complexes : Replacement ability of the ligands

In the case of metal complexes the effects of the ligands upon the R F values obtained in paper chrornatography are shown The replacement ability of the different ligands has been illustrated Chromatographie studies involving complexes were divided into homogeneous and non-homogeneous types and the experimental results explained accordingly