10,488 research outputs found

    Diversity, Stability, Recursivity, and Rule Generation in Biological System: Intra-inter Dynamics Approach

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    Basic problems for the construction of a scenario for the Life are discussed. To study the problems in terms of dynamical systems theory, a scheme of intra-inter dynamics is presented. It consists of internal dynamics of a unit, interaction among the units, and the dynamics to change the dynamics itself, for example by replication (and death) of units according to their internal states. Applying the dynamics to cell differentiation, isologous diversification theory is proposed. According to it, orbital instability leads to diversified cell behaviors first. At the next stage, several cell types are formed, first triggered by clustering of oscillations, and then as attracting states of internal dynamics stabilized by the cell-to-cell interaction. At the third stage, the differentiation is determined as a recursive state by cell division. At the last stage, hierarchical differentiation proceeds, with the emergence of stochastic rule for the differentiation to sub-groups, where regulation of the probability for the differentiation provides the diversity and stability of cell society. Relevance of the theory to cell biology is discussed.Comment: 19 pages, Int.J. Mod. Phes. B (in press

    Proton-neutron alignment in the yrast states of 66^{66}Ge and 68^{68}Ge

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    The 66^{66}Ge and 68^{68}Ge nuclei are studied by means of the shell model with the extended P+QQP+QQ Hamiltonian, which succeeds in reproducing experimentally observed energy levels, moments of inertia and other properties. The investigation using the reliable wave-functions predicts T=0, J=9 one-proton-one-neutron (1p1n1p1n) alignment in the g9/2g_{9/2} orbit, at high spins (141+14_1^+, 161+16_1^+ and 181+18_1^+) in these N≈ZN \approx Z even-even nuclei. It is shown that a series of the even-JJ positive-parity yrast states (observed up to 261+26_1^+ for 68^{68}Ge) consists of the ground-state band and successive three bands with different types of particle alignments (two-neutron, 1p1n1p1n, two-proton-two-neutron) in the g9/2g_{9/2} orbit.Comment: 4 pages, 5 figures, to be published in Pyhs. Rev.

    Shape transition and oblate-prolate coexistence in N=Z fpg-shell nuclei

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    Nuclear shape transition and oblate-prolate coexistence in N=ZN=Z nuclei are investigated within the configuration space (2p3/22p_{3/2}, 1f5/21f_{5/2}, 2p1/22p_{1/2}, and 1g9/21g_{9/2}). We perform shell model calculations for 60^{60}Zn, 64^{64}Ge, and 68^{68}Se and constrained Hartree-Fock (CHF) calculations for 60^{60}Zn, 64^{64}Ge, 68^{68}Se, and 72^{72}Kr, employing an effective pairing plus quadrupole residual interaction with monopole interactions. The shell model calculations reproduce well the experimental energy levels of these nuclei. From the analysis of potential energy surface in the CHF calculations, we found shape transition from prolate to oblate deformation in these N=ZN=Z nuclei and oblate-prolate coexistence at 68^{68}Se. The ground state of 68^{68}Se has oblate shape, while the shape of 60^{60}Zn and 64^{64}Ge are prolate. It is shown that the isovector matrix elements between f5/2f_{5/2} and p1/2p_{1/2} orbits cause the oblate deformation for 68^{68}Se, and four-particle four-hole (4p−4h4p-4h) excitations are important for the oblate configuration.Comment: 6 pages, 5 figures, accepted for publication in Phys. Rev.

    Cosmological Family Asymmetry and CP violation

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    We discuss how the cosmological baryon asymmetry can be achieved by the lepton family asymmetries of heavy Majorana neutrino decays and they are related to CP violation in neutrino oscillation, in the minimal seesaw model with two heavy Majorana neutrinos. We derive the most general formula for CP violation in neutrino oscillation in terms of the heavy Majorana masses and Yukawa mass term. It is shown that the formula is very useful to classify several models in which e−e-, μ−\mu- and τ−\tau-leptogenesis can be separately realized and to see how they are connected with low energy CP violaton. To make the models predictive, we take texture with two zeros in the Dirac neutrino Yukawa matrix. In particular, we find some interesting cases in which CP violation in neutrino oscillation can happen while lepton family asymmetries do not exist at all. On the contrary, we can find e−e-, μ−\mu- and τ−\tau-leptogenesis scenarios in which the cosmological CP violation and low energy CP violation measurable via neutrino oscillations are very closely related to each other. By determining the allowed ranges of the parameters in the models, we predict the sizes of CP violation in neutrino oscillation and ∣Ve3MNS∣|V_{e3}^{MNS}|. Finally, the leptonic unitarity triangles are reconstructed.Comment: 22 pages, 9 figures A figure caption correcte

    Projection neurons in lamina III of the rat spinal cord are selectively innervated by local dynorphin-containing excitatory neurons

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    Large projection neurons in lamina III of the rat spinal cord that express the neurokinin 1 receptor are densely innervated by peptidergic primary afferent nociceptors and more sparsely by low-threshold myelinated afferents. However, we know little about their input from other glutamatergic neurons. Here we show that these cells receive numerous contacts from nonprimary boutons that express the vesicular glutamate transporter 2 (VGLUT2), and form asymmetrical synapses on their dendrites and cell bodies. These synapses are significantly smaller than those formed by peptidergic afferents, but provide a substantial proportion of the glutamatergic synapses that the cells receive (over a third of those in laminae I–II and half of those in deeper laminae). Surprisingly, although the dynorphin precursor preprodynorphin (PPD) was only present in 4–7% of VGLUT2 boutons in laminae I–IV, it was found in 58% of the VGLUT2 boutons that contacted these cells. This indicates a highly selective targeting of the lamina III projection cells by glutamatergic neurons that express PPD, and these are likely to correspond to local neurons (interneurons and possibly projection cells). Since many PPD-expressing dorsal horn neurons respond to noxious stimulation, this suggests that the lamina III projection cells receive powerful monosynaptic and polysynaptic nociceptive input. Excitatory interneurons in the dorsal horn have been shown to possess IA currents, which limit their excitability and can underlie a form of activity-dependent intrinsic plasticity. It is therefore likely that polysynaptic inputs to the lamina III projection neurons are recruited during the development of chronic pain states

    Quark mass dependence of the vacuum electric conductivity induced by the magnetic field in SU(2) lattice gluodynamics

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    We study the electric conductivity of the vacuum of quenched SU(2) lattice gauge theory induced by the magnetic field B as a function of the bare quark mass m. The conductivity grows as the quark mass decreases. Simplest power-like fit indicates that the conductivity behaves as B/sqrt(m). We discuss the implications of this result for dilepton angular distributions in heavy ion collisions.Comment: 5 pages RevTeX, 4 figure

    Leptogenesis and Low energy CP violation, a link

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    How is CP violation of low energy related to CP violation required from baryon number asymmetry ? We give an example which shows a direct link between CP violation of neutrino oscillation and baryogenesis through leptogenesis.Comment: 3 pages and 2 figures, Talk presented at 4th Nufac02, July 1-6, 200
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