Collapse of Primordial Filamentary Clouds under Far-Ultraviolet Radiation

Collapse and fragmentation of primordial filamentary clouds under isotropic dissociation radiation is investigated with one-dimensional hydrodynamical calculations. We investigate the effect of dissociation photon on the filamentary clouds with calculating non-equilibrium chemical reactions. With the external radiation assumed to turn on when the filamentary cloud forms, the filamentary cloud with low initial density ($n_0 \le 10^2 \mathrm{cm^{-3}}$) suffers photodissociation of hydrogen molecules. In such a case, since main coolant is lost, temperature increases adiabatically enough to suppress collapse. As a result, the filamentary cloud fragments into very massive clouds ($\sim 10^5 M_\odot$). On the other hand, the evolution of the filamentary clouds with high initial density ($n_0>10^2 \mathrm{cm^{-3}}$) is hardly affected by the external radiation. This is because the filamentary cloud with high initial density shields itself from the external radiation. It is found that the external radiation increases fragment mass. This result is consistent with previous results with one-zone models. It is also found that fragment mass decreases owing to the external dissociation radiation in the case with sufficiently large line mass.Comment: 26 pages, 15 figures, accepted by PAS

Formation of Hot Planets by a combination of planet scattering, tidal circularization, and Kozai mechanism

We have investigated the formation of close-in extrasolar giant planets through a coupling effect of mutual scattering, Kozai mechanism, and tidal circularization, by orbital integrations. We have carried out orbital integrations of three planets with Jupiter-mass, directly including the effect of tidal circularization. We have found that in about 30% runs close-in planets are formed, which is much higher than suggested by previous studies. We have found that Kozai mechanism by outer planets is responsible for the formation of close-in planets. During the three-planet orbital crossing, the Kozai excitation is repeated and the eccentricity is often increased secularly to values close enough to unity for tidal circularization to transform the inner planet to a close-in planet. Since a moderate eccentricity can remain for the close-in planet, this mechanism may account for the observed close-in planets with moderate eccentricities and without nearby secondary planets. Since these planets also remain a broad range of orbital inclinations (even retrograde ones), the contribution of this process would be clarified by more observations of Rossiter-McLaughlin effects for transiting planets.Comment: 15 pages, 16 figures, Accepted for publication in Ap

Courant sigma model and L∞L_\infty-algebras

The Courant sigma model is a 3-dimensional topological sigma model of AKSZ type which has been used for the systematic description of closed strings in non-geometric flux backgrounds. In particular, the expression for the fluxes and their Bianchi identities coincide with the local form of the axioms of a Courant algebroid. On the other hand, the axioms of a Courant algebroid also coincide with the conditions for gauge invariance of the Courant sigma model. In this paper we embed this interplay between background fluxes of closed strings, gauge (or more precisely BRST) symmetries of the Courant sigma model and axioms of a Courant algebroid into an $L_\infty$-algebra structure. We show how the complete BV-BRST formulation of the Courant sigma model is described in terms of $L_\infty$-algebras. Moreover, the morphism between the $L_\infty$-algebra for a Courant algebroid and the one for the corresponding sigma model is constructed.Comment: 34 pages. v2: typos corrected, published versio

Characteristics of a multilayer eddy‐current‐type ac magnetic coil with a cooling system

This paper deals with the performance characteristics of a new ac high magnetic field generator based on the effect of eddy currents. We have proposed a new ac high magnetic field generator and have obtained magnetic fields up to 15 T at 60 Hz. The proposed structure consists of layers of exciting coils and conductors built in concentric circles. The eddy currents in the conductor flow close to the hole in the conductor. The magnetic flux induced by the eddy currents is concentrated within the hole, and an ac high magnetic field is produced. A procedure for estimating the optimum shape and number of layers required to increase the concentration effect, together with a design of the colling system necessary for continuous operation, is presented

Initiation of DNA interstrand cross-link repair in humans: the nucleotide excision repair system makes dual incisions 5' to the cross-linked base and removes a 22- to 28-nucleotide-long damage-free strand.

Most DNA repair mechanisms rely on the redundant information inherent to the duplex to remove damaged nucleotides and replace them with normal ones, using the complementary strand as a template. Interstrand cross-links pose a unique challenge to the DNA repair machinery because both strands are damaged. To study the repair of interstrand cross-links by mammalian cells, we tested the activities of cell extracts of wild-type or excision repair-defective rodent cell lines and of purified human excision nuclease on a duplex with a site-specific cross-link. We found that in contrast to monoadducts, which are removed by dual incisions bracketing the lesion, the cross-link causes dual incisions, both 5' to the cross-link in one of the two strands. The net result is the generation of a 22- to 28-nucleotide-long gap immediately 5' to the cross-link. This gap may act as a recombinogenic signal to initiate cross-link removal

Numerical analysis of a new magnetic frequency tripler with series-connected reactors

The authors propose a new magnetic frequency tri­pler with series-connected reactors, and present a numerical analysis of the tripler. In the analysis, Φ-i characteristic of saturable reactor is approximated by (if th-order plynominal, and nonlinear ordinary d if­ferencial equations for flux linkage are derived from an equ ivalenc circuit. The nonlinear simultaneous equations, which are obtained by using the method of Harmonic Balance, are solved by an improved Newton\u27s method. The improved numerical method enables to de­termine optimum gap length and coil turns of the re­actors. Experimental results, which are obtained by using the reactors with the numerically determined gap length and coil turns, show a constant voltage charac­teristic up to a certain load and a drooping character­istic above that load

Four components three dimensional FEM analysis of flux concentration apparatus with four plate

This paper deals with the four component three dimensional FEM analysis of a flux concentration model with four thick conducting plates placed between a pair of a.c.-excited coils. We have already analyzed a flux concentration apparatus with two conducting plates by using a newly developed iterative 3-D calculation method.[1] [2] An improved formulation is also treated in this paper. This calculation method is applied to the present four-plate type model, to prove its adaptability and to search for more efficient design of such apparatus. Distributions of flux densities, eddy currents and scalar potentials are calculated and discussed. The role of the scalar potential for the 3-D eddy current diffusion problems is also interpreted, based on our calculation results

Three dimensional flow of eddy currents in flux concentration apparatus

This paper deals with three dimensional analysis of the eddy current distribution in a cylinder-type flux concentration apparatus by using a four component finite element calculation method. In order to solve z-ward component of eddy currents in a new model with multi-rims, boundary conditions of four components are discussed. We have already examined and analyzed several types of flux concentration apparatus, which utilize the flux concentration effect of eddy currents [1][2][3][4]. However, in these models treated in the references shown above, we do not have to consider the current component perpendicular to the excitation current. In order to obtain three dimensional flow of eddy currents, boundary conditions for four variables should-be selected carefully. Boundary conditions especially for z-ward vector potential and the scalar potential are discussed