Application of ANOVA into the Evaluation of Homogeneity of Materials

The concept of homogeneity of materials and the aim for the evaluation of homogeneity were introduced. It was discussed in detail for the application of one-way ANOVA into the evaluation of homogeneity of materials and the role which a statistical quantity plays in the different range. It can be illustrated that a small F value is necessarily not considered as a criterion of qualified homogeneity. It was also pointed out that the inhomogeneity with sample may cause a small F value. Based on the theoretical explanation, an equation was given for the threshold value of small F. A calculation of the threshold value of small F occurring in the common experiments was made using the routines of numerical integration. An investigation into the origin of small F value was carried out. Moreover, the regional inhomogeneity and its criteria were also shown.

Influence of site of regional ischemia on LV cavity shape change in dogs

We assessed whether altering the location of acute ischemia produced differing and consistent changes in cavity shape in the canine left ventricle. Twenty anesthetized open-chest dogs underwent transient occlusion of the left anterior descending (LAD) or circumflex (Circ) artery, and cavity shape change was recorded in two-dimensional short-axis echocardiograms. The extent of injury was assessed by radiolabeled microspheres. Shape was analyzed by converting digitized endocardial contours into polar form and expressing the result as a Fourier series. Series terms reflected specific shape deformations, i.e., 2nd term would equal "elongation," 3rd term would equal "triangular." During LAD occlusions, 32.5 +/- 3.0% of the ventricle was hypoperfused compared with 29.8 +/- 2.9% during Circ occlusions (NS). Normal ventricular shape became more circular during ejection indicated by a reduction in the power in nearly all of the Fourier spectra components. During Circ occlusion, the chamber became more elongated, seen in a 63 +/- 16% rise in the 2nd component, and overall shape significantly less circular at end systole than at end diastole. LAD occlusion produced an entirely different pattern, one with no significant elongation but the development of a more triangular shape (86 +/- 27% rise in the 3rd term) by end systole. We conclude that there are characteristic and contrasting shape deformations in LV short-axis contours that depend on the site of ischemic injury. These changes may relate to site-specific geometry and loading, and they point to potential limitations of left ventricular models that do not account for regional inhomogeneity.

Effect of regional inhomogeneity on collateral airway resistance

We studied the interaction of transpulmonary pressure (Pao) and the pressure in an isolated sublobar lung segment (Ps) on collateral resistance (Rcoll) in excised dog lungs. A double-lumen catheter was advanced through the trachea and wedged in a peripheral airway. Gas flowed through the outer lumenof the catheter (Vcoll) to enter the segment while Ps was measured by the inner lumen. Collateral resistance was calculated as Rcoll = (Ps - Pao)/Vcoll. At constant Ps, raising Pao sharply decreased Rcoll, but at constant Pao, raising Ps increased Rcoll. Replotting these data showed that Rcoll was related to the pressure difference between the segment and the remainder of the lobe (Ps - Pao), such that raising Ps - Pao caused no change in Rcoll at lower Pao but increased Rcoll at higher Pao. Similarfindings occurred in the lungs of closed-chest anesthetized dogs. We propose that this technique measures the sum of resistances of airways and collateral channels found in the segment body (Rs) and of those passing through the segment-lobar parenchymal interface (Ri). Raising Ps - Pao decreases Rs because of the volume dependency of airway resistance and increases Ri due to tissue distortion at the interface occurring as a result of inhomogeneous segment inflation. The net change in measured Rcoll depends on which of its components change in greatest magnitude. This effect varies with Pao due to thehyperbolic relationship of Pao with airway and collateral resistance.

Regional inhomogeneity of alveolar air and R.Q. differences in the lungs of the normal dog

Regional inhomogeneity of alveolar air was studied by simultaneous sampling through catheters in primary or secondary bronchi, at the end of normal expiration in dogs under sodium pentobarbital anesthesia. With dogs lying on the back, the right lung usually had the lower Pco2, higher Po2 and higher R. P( t) < .001 for each difference. In the side-lying position the ‘down’ lung usually had the higher Po2 and R unless the catheters were placed so deep as to differentially obstruct the airway in that lung. Submitted on July 3, 1958