Masumi Hattori

Favorable effects of epidural analgesia on hemodynamics, oxygenation and metabolic variables in the immediate post‐anesthetic period

Fourteen adult patients undergoing elective major abdominal surgery were divided into two groups. One group received epidural and general anesthesia (epidural group), and 20 ml of 0.125% bupivacaine and 2 mg of morphine were administered epidurally about 30 min before the end of the operation for post‐anesthetic analgesia. The other group (control group) received general anesthesia alone with nitrous oxide, oxygen and enfiurane. Flow‐directed pulmonary arterial and radial arterial catheters were inserted preoperatively, and hemodynamic, respiratory, neuroendocrine and metabolic variables were measured serially. The data were compared during anesthesia and the immediate post‐anesthetic recovery period. In the control group, the plasma epinephrine level in the post‐anesthetic recovery period increased about four times over the anesthetic period. Oxygen consumption was increased and mixed venous oxygen saturation was decreased significantly. There was a close linear correlation between oxygen consumption (Y) and plasma epinephrine (X) level: Y = 285.7X + 90.5 (P < 0.01, r = 0.72). On the other hand, plasma epinephrine, oxygen consumption and mixed venous oxygen saturation did not change significantly in the epidural group in the post‐anesthetic recovery period. There was also a close linear correlation between oxygen consumption (Y) and oxygen delivery (X): Y = 0.22X ‐32.0 (P < 0.01, r = 0.89). We conclude that the surgical stress and anesthetic reversal may seriously influence neuroendocrine responses and subsequently increase plasma epinephrine. Tissue oxygenation and metabolic imbalance may occur due to the rapid increase of epinephrine in the postanesthetic recovery period. Epidural analgesia at this period may play a more important role and have a more favorable effect on the tissue metabolism.

Thermostatistical Investigation of Magnetic and Thermal Properties of Cobalt Dichalcogenide Compound Co(SxSe1-x)2 with Pyrite Structure

A statistical-mechanical calculation on the system of spins of quantum number one half which constitute a face-centred cubic lattice and couple not only with the nearest-neighbour spins but also with the second-neighbour spins due to the exchange interactions is carried out with the use of the inverse temperature expansion. By the application of this calculation, the magnetic and thermal properties of cobalt dichalcogenide compound Co(S x Se 1- x ) 2 of various values of the fraction x with pyrite structure is discussed, assuming that the antiferromagnetic exchange coupling between a pair of second-neighbour spins gets stronger with decreasing of the fraction x . The correspondence between the theory and experiment is quite well in all respects. The appearance of a certain metamagnetic transition is predicted in the compound of an intermediate x value which is not ferromagnetic although no ample measurement of the magnetization in variable magnetic field at various temperatures has been carried out yet en...

Magnetization Process of the Heisenberg Spin System on the F.C.C. Lattice with Second-Neighbor Interaction

By making use of the statistical-mechanical calculation based upon the method of expansion into inverse-temperature power series, magnetic properties of the Heisenberg spin system ( S =1/2) with the first- and second-neighbor exchange interactions, J 1 (>0) and J 2 (<0), are investigated more extensively than in the previous paper. It is shown that the system exhibits more various magnetic properties depending on the exchange ratio α= J 2 / J 1 ; that is, it exhibits, in the order of decreasing α, a usual ferromagnetism, ferromagnetism accompanied with a type of metamagnetism which is named “exchange-compensated paramagnetism”, a sole exchange-compensated paramagnetism and antiferromagnetism, the last of which is of no concern in the present paper. These properties have been significantly recognized in the observations on the compound series, Co(S x Se 1- x ) 2 .

Quantum Variational Principle of Irreversible Processes in a Magnetic field

Quantum variational principle of irreversible processes is generalized to the systems under the uniform magnetic field. For the electron transport in impurity potentials as a typical example, contractions of the density matrix are performed without any approximation in two steps; first the off-diagonal part of the density matrix is eliminated and subsequently the even part with respect to time reversal. In consequence the maximum principle is derived for the odd part of the diagonal elements of the density matrix. This means the contraction of the density matrix brings about irreversibility. The variational principle is shown to be closely related to that for the conventional Boltzmann–Bloch equation and is regarded as its fundamental version. The dependences of the density matrix on the magnetic field and wave number are discussed.

UNIFIED VARIATIONAL PRINCIPLES FOR THE VON NEUMANN, MASTER AND BOLTZMANN-BLOCH EQUATIONS AND THE T-MATRIX

The variational principle of irreversible processes, which was previously presented for the von Neumann equation as a stationarity problem and then converted into a maximum problem by contracting the density matrix perturbatively, is reinvestigated w.r.t. the contraction of the density matrix. The present contraction relies on the T-matrix theory of scattering, where no perturbational consideration enters. By taking the electron transport in solids as a typical example, the contraction is performed in two steps: the even component of the density matrix as to time reversal is eliminated first and then the off-diagonal elements in the scheme of diagonalizing the unperturbed Hamiltonian. The maximum problem thus obtained is for the diagonal elements of the odd component of the density matrix. The maximum condition gives the master equation, which is reduced to the Boltzmann-Bloch equation in the scheme of one-body picture. It is noticeable in this equation that the collision term is given in terms of the T-matrix in scattering theory.

Critical Relaxation in Dipolar Ising Model at Marginal Dimension

The equation of motion for a dipolar Ising Model at a marginal dimension d = 3 is studied on the basis of the renormalized field theory. It is shown that the temperature dependence of a nonlinear relaxation time t ( n l ) is related to a linear one t ( l ) as t ( n l ) = t ( l ) M s + , where M s + is defined as the spontaneous magnetization at the temperature T c -|τ| irrespective of the sign of the renormalized temperature difference τ= T - T c .