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901.
Prof. Dr. A. Mäde 《International journal of biometeorology》1959,3(1):311-319
Ohne Zusammenfassung 相似文献
902.
The present-day practices of electrocardiography and vectorardiography are based upon the theory that the surface potential
differences can be assumed to be due to a single dipole inside the body. It is shown in this paper that a dipole cannot account
for all the surface potentials due to realistic current generators, and hence the determination of the current generator from
surface potential measurements based upon such a theory will lead to inconsistent representations of the heart for one and
the same subject.
To demonstrate this point two eccentric dipoles of different strengths and locations representing two muscle fibers are taken
to be the current generator in a homogeneous spherical conductor. The exact surface potentials are then expressed by means
of the “interior sphere theorem” of the authors. With these expressions the magnitude, direction, and location of the resultant
dipole are determined by the method of D. Gabor and C. V. Nelson (J. App. Physics,25, 413–16, 1954). The surface potentials due to this resultant dipole are again exactly expressed by means of the “interior
sphere theorem” and compared with those due to the eccentric dipoles assumed. It can be seen that the differences can be considerable.
It is suggested that the multipole model of the authors (Bull. Math. Biophysics,20, 203–16, 1958) be used as a more accurate and the only unique representation of the heart.
This investigation was supported by the National Heart Institute under a research grant H-2263(c). 相似文献
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Of four species studied, tolerance of extreme temperatures in greatest in Spirorbis pagenstecheri (which extends highest on the shore) and least in S. corallinae (which always occurs immersed in water). The latter species breeds between May and August, the other three from May to October. S. borealis liberates its larvae mainly at the moon's quarters, but this fortnightly rhythm is less obvious in S. corallinae and not found in the other two species. S. corallinae differs from S. borealis in being slower to re-emerge after disturbance and in having a lesser breeding size, maximum size and life span. Growth in the laboratory is slower in S. tridentatus than in the other species. Growth of S. borealis under natural conditions is much faster in summer than in winter. 相似文献