Static-dynamic friction transition of FRP esthetic orthodontic wires on various brackets by suspension-type friction test.

A new testing apparatus for the measurement of frictional properties was designed and the frictional coefficients were obtained and compared with each other in various combinations of brackets and orthodontic wires, including esthetic fiber-reinforced plastic (FRP) wire that was especially designed and manufactured. Three kinds of wires (stainless steel, nickel-titanium, and FRP) and four brackets (single-crystal alumina, polycrystalline alumina, polycarbonate, and stainless steel) were used. The testing was done under dry and wet conditions. The friction testing equipment was designed to attach the bracket to a C-shaped bar suspended with a variable mass, and sliding along a fixed wire. The transition between static and dynamic friction was measured as a breakaway force, with the use of a universal test machine. In addition to material properties, this testing fixture eliminates geometrical factors, such as the rotational moment at the edge of the bracket slot, deflection of the orthodontic wire, and tension of the ligature wire. Nearly ideal frictional properties between materials are obtained. The frictional properties of FRP wire were similar to those of metal wires on all brackets, except the polycrystalline alumina bracket. The frictional coefficient between the polycrystalline ceramic bracket and FRP wire was larger than that of other combinations. There was little difference in frictional coefficients between dry and wet conditions.

The transient appearance of small blastoid cells in the marrow after bone marrow transplantation.

Of 14 patients who underwent allogeneic or syngeneic bone marrow transplantation, 6 had a transient appearance of small blastoid cells in the bone marrow after transplantation. Most of these patients (11) had leukemia, although 3 had severe aplastic anemia. The cells were 8-18 micron in diameter and had scant cytoplasm and dense nuclei with smooth, homogeneous chromatin. They often had distinct nuclear clefts. These cells constituted 4.0-21.3% of the total number of bone marrow cells. They were not reactive with peroxidase, alpha-naphtyl butylate esterase, naphthol AS-D chloroacetate esterase, or periodic acid-Schiff stains. Immunocytochemical analysis revealed that the small blastoid cells expressed terminal deoxynucleotidyl transferase, Ia-like, CD19, and CD10 antigens and cytoplasmic mu heavy chains, indicating a precursor B-cell phenotype. CD20 antigen was not expressed on these cells. The data suggest that cytoplasmic mu may be expressed earlier than CD20 antigen in the differentiation of B-cell lineage. The morphologic, cytochemical, and immunophenotypic characteristics did not distinguish these nonneoplastic cells distinctly from leukemic lymphoblastic cells. The increase of small blastoid cells was a transient and self-limited phenomenon, in contrast to that of neoplastic blasts. These cells should be recognized as a common component of the bone marrow of marrow transplant recipients. The significance and role of these cells in immune recovery and hematopoiesis remain uncertain.

Supracellular structural principle of multicellular organisms.

All the supracellular structures composed of compact aggregates of constituent units are subordinate to a single structural principle. It is a particular space division called equilibrium space division (ESD) by the author. EDS is a geometrical expression of the second law of thermodynamics corresponding to a state of minimized potential energy of the system of constituent units assembled by uniform or polarized centripetal force. It is a statistical process under incomplete mechanical restrictions and cannot entirely be reduced to deterministic mechanisms. Supracellular structures are accordingly not directly prescribed by genetic information based upon the template function of DNA molecules. Blood vessels are essentially localized on the edges of ESD, so that their geometry is influenced by this particular space division. Some geometrical parameters of arteries are theoretically derived from the geometry of ESD, partly with the aid of a model of space division by uniform beta-tetrakaidecahedra, which approximately replaces ESD.

Supracellular structural principle and geometry of blood vessels.

All the supracellular structures of multicellular organisms are subordinate to a single structural principle. It is a particular space division minimizing the potential energy of the constituent units in a field of mechanical force and is specified as equilibrium space division (ESD). Three-dimensional ESD is characterized by the feature that three faces unite to an edge and four edges converge to a corner, but other geometrical characters are susceptible to variation. Blood vessels are localized predominantly on edges of ESD, so that their geometry depends largely on ESD. ESD is represented approximately by a model of complete space division with uniform beta-tetrakaidecahedra, and some geometrical parameters of blood vessels can be derived theoretically from ESD, partly with the aid of the above-mentioned model. ESD is a statistical process under incomplete restrictions. It is consequently impossible to interpret the morphogenesis of supracellular structures directly from genetic information in a deterministic manner.

Estimation of the distribution of ellipsoids with random test lines.

The distribution F(lambda) of the length lambda of chords delivered by a random test line of unit length, which intersects a sufficiently large number of ellipsoids of different sizes but of uniform shape randomly oriented and dispersed in a three-dimensional space of unit volume, is give by (formula: see text). In this equation, phi(e) is a coefficient determined by two eccentricities of the ellipsoids and N(r) is the distribution function of their major semi-axes r. In the case of spheres phi(e) is 1, but otherwise it is always smaller than 1. N(r) can be further expressed as the product of the probability distribution p(r) of r and the total number Nvo of the ellipsoids in a unit volume. On account of the above equation, it is possible to extend the application of the histometrical methods of spheres with the use of chord length immediately to a group of ellipsoids of uniform shape, so far as the estimation of the parameters of p(r) is concerned. Even with a group of ellipsoids of different shapes, the same principle is valid, provided that all the subgroups of ellipsoids of different eccentricities have a common p(r). Nvo is most practically estimated from Nvo=Tv(h)/2h, in which Tv(h) is the number of tangential points made by ellipsoids with a test plane of unit surface area during its transit h in the direction perpendicular to itself.

Left ventricular stiffness and chamber geometry in the pressure-overloaded hypertrophied heart.

Pressure-overloaded hypertrophy of the left ventricle (LV) was produced by coarctation of the ascending aorta in 7 dogs. The overall mean weight of the left ventricle (LVW) was 7.86 +/- 1.49 (S.D.) g/kg body weight; (normal, 5.99 +/- 0.70 g/kg: p less than 0.05). After potassium arrest, pressure-volume (P-V) relationships were examined with the left ventricles isolated from the normals and from the dogs of left ventricular hypertrophy (LVH-dogs). In both groups, the P-V relationships could be expressed by an equation deltaV=a-be-cP throughout the range of filling pressure of 2.5 to 35 cmH2O, where deltav was the actual volume change of LV, P intraventricular pressure, and a, b and c constants. A sensitive index of LV stiffness, the half-inflation pressure (h), was defined as 1n (2b/a)/c. In hypertrophied hearts, h was 10.5 +/- 0.7 cmH2O; (normal 8.0 +/- 0.4 cmH2O; P less than 0.001). The ratio of LVW to LVVp=h (the left ventricular volume at h) in hypertrophy, which was related to the LV chamber geometry, was 3.1 +/- 0.6 in contrast with the normal value of 2.0 +/- 0.3. The development of concentric hypertrophy was thus demonstrated. Moreover, h was closely correlated with LVW/LVVp=h in both the normals and the LVH-dogs (r=0.83; p less than 0.01). On the other hand, an index of LV wall stiffness h/LVW/LVVP=h was relatively constant. Therefore, the increase of LV stiffness in the LVH-dogs was attributed to the change in chamber geometry.

Errors of parameters of distribution functions for spherical bodies stochastically estimated on a random test plane.

The parameters of some distribution functions for the radius of spherical bodies randomly dispersed in a three-dimensional space can be estimated on a random test plane of unit surface area. In this estimation the set of measured Nao, delta and (delta2) or that of Nlambdao, lambda and (lambda2) is used. They are number of circles, arithmetical mean and secondary moment of circle diameters or number of chords delivered by intersection of a test line of unit length with circles, arithmetical mean and secondary moment of chord length, respectively. Provided that the region of measurement is sufficiently large, intraregional errors of these quantities expressed as the squares of coefficient of variation C are approximately: [C(Nao)]omega2=1/Nao, [C(delta)omega2=(32/3pi2)(Q3/Q2(2))(1/Nao) and [C(delta2)]omega2=(6/5)(Q5/Q3(2))(1/Nao); [C(Nlambdao)]omega2=1/MNlambdao, [C(lambda)]omega2=(9/8)(Q4Q2/Q3(2))(1/MNlambdao) and [C(lambda2)]omega2=(4/3)(Q6Q2/Q4(2))(1/MNlambdao). In these expressions Qn is a quotient defined by (Dn)/Dn, D and n being sphere diameter and a positive integer, respectively. The first three expressions may be used in these forms as the errors for the total region containing spheres. In the second three expressions M is the number of random test lines of unit length. When M is small, they can stand for the errors of the total region. In the case of large M, however, interregional errors or errors of sampling have to be added to them. The geometrical parameter of a distribution function of D is estimated from (delta2)/delta2 or (lambda2)/lambda2. The error of this ratio W is given by: [C(W)]2=[C(X2)-2C(X)]2, where X stands for delta or lambda.

Errors of parameters of distribution functions for spherical bodies stochastically estimated with parallel test lines of regular and narrow intervals.

The parameters of some distribution functions for the radius of spherical bodies randomly dispersed in a three-dimensional space can be estimated with a grating of parallel test lines of regular intervals superposed on a test plane of unit surface area. The interval of the test lines is set narrower than the mean diameter of the circles on the test plane. The errors of number Nlambdao of chords per test line of unit length, arithmetical mean lambda and secondary moment (lambda2) of the length of individual chords are: [C(Nlambdao)*]2=(4/9pi)(Q3/Q2(2))(1/M2lambdaNlambdao)+(4/pi)(lambda/Nlambdao), [C(lambda)*]2=(pi/4)[(32/3pi2) - 1](1/M2lambdaNlambdao)+[(4/pi)-(3pi/8)(Q2(2)/Q3)](lambda/Nlambdao) and [C(lambda2)*]2 = (1024/2025pi)(Q5Q3/Q4(2))(1/M2lambdaNlambdao)+4[(4/pi)-(3pi/8)(Q2(2)/Q3)](lambda/Nlambdao). The first and second terms of the right sides of these expressions represent intraregional and interregional errors, respectively; * denotes the error for the total region; M is the expectation of the number of test lines of unit length covering the test plane; and Qn a quotient (Dn)/Dn of sphere diameter D, n being a positive integer. Intraregional errors are inversely proportional to M2 with the grating, while they are inversely proportional only to M with random test lines. The use of regularly arranged test lines is consequently effective in minimizing intraregional errors.

Quantitative analysis of cardiac hypertrophy due to pressure load in reference to the relations of blood pressure, left ventricular weight and left ventricular capacity.

In almost all of the cases of cardiac hypertrophy due to sustained hypertension, left ventricular capacity is increased in proportion to increased left ventricular weight, even in the absence of manifest cardiac insufficiency. The condition is regarded as the general expression of cardiac response to pressure load, and the concept of "isomorphic hypertrophy" is proposed. Concentric hypertrophy of the current concept is observed only on rare special occasions, and its role in cardiac adaptation to pressure load is obscure. The increase in myocardial mass is sufficient to maintain the work done by a unit myocardial volume at a normal level. However, the calculation on pertinent models demonstrates that hypertrophied hearts of any type expel the normal stroke volume with smaller shortening of muscle fibers under larger stress, which is further elevated with the progress of cardiac contraction. Because the maximum force generated by muscle fibers declines with advancing cardiac contraction, hypertrophied hearts harbor a latent risk of mechanical insufficiency. Even under pressure load, ventricular dilation seems to precede the re-inforcement of ventricular wall in the development of cardiac hypertrophy. A common mechanism may be therefore assumed underlying the development and performance of all types of hypertrophied hearts, regardless of the difference in the character of physical loads.

Morphometrical method to estimate the parameters of distribution functions assumed for spherical bodies from measurements on a random section.

The general equations to correlate the distribution of the radius r of spheres randomly dispersed in the three-dimensional space with measurements on a random test plane are (see article) and (see article) for the diameter delta of circular sections of spheres; and (see article) and (see article) for the length lambda of chords delivered by intersection of a random test line. In the above expressions Nvo, Nao and Nlambdao are the numbers of spheres in a unit volume, of circles on a unit surface area and of chords per unit length of a test line, respectively; n is O or a positive integer; r the arithmetical mean of r; (deltan) and (lambdan) the means of the n-th powers of delta and lambda, respectively; and Qn a quotient defined by Qn = (rn)/rn. The ratio of measured (delta2/delta2 or (lambda2/lambda2 is used for calculating one of the parameters of assumed theoretical distribution functions. A second parameter is then estimated from delta or lambda. The method was applied to the normal pancreatic islets, and the use of chord length lambda was preferred to that of diameter delta, because the error due to the failure in identifying very small islet sections was minimized in the former.