Effects of magnetic fields on radiatively overstable shock waves

We discuss high-resolution simulations of one-dimensional, plane-parallel shock waves with mean speeds between 150 and 240 km/s propagating into gas with Alfven velocities up to 40 km/s and outline the conditions under which these radiative shocks experience an oscillatory instability in the cooling length, shock velocity, and position of the shock front. We investigate two forms of postshock cooling: a truncated single power law and a more realistic piecewise power law. The degree of nonlinearity of the instability depends strongly on the cooling power law and the Alfven Mach number: for power-law indices \alpha < 0 typical magnetic field strengths may be insufficient either to stabilize the fundamental oscillatory mode or to prevent the oscillations from reaching nonlinear amplitudes.Comment: 11 text pages, LaTeX/AASTeX (aaspp4); 5 figures; accepted by Ap

Radiative instabilities in simulations of spherically symmetric supernova blast waves

High-resolution simulations of the cooling regions of spherically symmetric supernova remnants demonstrate a strong radiative instability. This instability, whose presence is dependent on the shock velocity, causes large-amplitude fluctuations in the shock velocity. The fluctuations begin almost immediately after the radiative phase begins (upon shell formation) if the shock velocity lies in the unstable range; they last until the shock slows to speeds less than approximately 130 km/s. We find that shock-velocity fluctuations from the reverberations of waves within the remnant are small compared to those due to the instability. Further, we find (in plane-parallel simulations) that advected inhomogeneities from the external medium do not interfere with the qualitative nature of the instability-driven fluctuations. Large-amplitude inhomogeneities may alter the phases of shock-velocity fluctuations, but do not substantially reduce their amplitudes.Comment: 18 pages text, LaTeX/AASTeX (aaspp4); 10 figures; accepted by Ap

パーティクル・ボードに関する研究 : (第6報)含脂率およびパーティクル・ディメンションが低比重ボードの材質におよぼす影響について

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Malignant cell transformation by the SV-40 DNA and phagocytic activity related to alteration of cell membranes

In vitro cell transformation of human embryo cells could be induced by the DNA purified from SV 40. The result shows clearly that cell transforms a part of viral DNA into the genome. In addition, for the purpose of clarifying th~ biological differences between the normal and transformants the alteration of cell membraneous structures of transformants (hamster and mouse fibroblasts) were observed from mechanism of phagocytosis. The iron colloid particles are taken up by normal diploid fibroblasts but not by the human and hamster transformants. This fact suggests a differ~nce in the molecular arrangement of the cell membranes between the normal and transformants. In the presence of histones, however, the transformants phagocytize the colloid particles very actively. The results show that cell membranes of transformants are altered in the molecular structure r~sponsible for the surface charge. In addition, there is no remarkable quantative differences of sialic acids on the cell surfaces of non-malignant and malignant transformants so that phagocytic activity might be correlated to the alteration of molecular composition of cell membrane itself rather than of cell surfaces, i. e, sialic acids.</p

Hierarchy of the Selberg zeta functions

We introduce a Selberg type zeta function of two variables which interpolates several higher Selberg zeta functions. The analytic continuation, the functional equation and the determinant expression of this function via the Laplacian on a Riemann surface are obtained.Comment: 14 page

Malignant transformation of human cell in vitro by the SV 40 DNA and related alteration in biological activity of cell membranes

In vitro cell transformation of human embryonic cells could be induced by DNA extracted from virions of SV 40 purified by density gradient centrifugation. The result shows clearly that cell transformation is in· duced by incorporation ofa part of viral DNA into the genome. In addition, for the purpose of clarifing the biological differences between the normal and transformant, the alteration of the cell membrane structures of transformants was observed from the mechanism of phagocytosis. The iron colloid particles are taken up by normal diploid fibroblasts but not by the human and hamster transformants. This fact suggests a difference in the molecular arrangement of the cell membranes between the normal and transformants. In the presence of histones, however, the transformants phagocytize the colloid particles very actively. The results show cell membranes of transformants are altered in the molecular structure responsible for the surface charge.</p

Arithmetical properties of Multiple Ramanujan sums

In the present paper, we introduce a multiple Ramanujan sum for arithmetic functions, which gives a multivariable extension of the generalized Ramanujan sum studied by D. R. Anderson and T. M. Apostol. We then find fundamental arithmetic properties of the multiple Ramanujan sum and study several types of Dirichlet series involving the multiple Ramanujan sum. As an application, we evaluate higher-dimensional determinants of higher-dimensional matrices, the entries of which are given by values of the multiple Ramanujan sum.Comment: 19 page

Solvable model of a phase oscillator network on a circle with infinite-range Mexican-hat-type interaction

We describe a solvable model of a phase oscillator network on a circle with infinite-range Mexican-hat-type interaction. We derive self-consistent equations of the order parameters and obtain three non-trivial solutions characterized by the rotation number. We also derive relevant characteristics such as the location-dependent distributions of the resultant frequencies of desynchronized oscillators. Simulation results closely agree with the theoretical ones