The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform

Carl P. Schmertmann - One of the best experts on this subject based on the ideXlab platform.

James R. Carey - One of the best experts on this subject based on the ideXlab platform.

Tetsuya J. Kobayashi - One of the best experts on this subject based on the ideXlab platform.

  • Pathwise analysis for a structured Population dynamics and its application to inference of cell states
    2019
    Co-Authors: Yuki Sughiyama, So Nakashima, Tetsuya J. Kobayashi
    Abstract:

    Control of the Stationary Population growth rate, which represents the averaged expansion rate of the total Population size, is ubiquitous problems in many fields. Theoretical studies to evaluate the Stationary Population growth rate and to analyze its behavior have been often conducted by ordinary- or partial-differential equation approaches by focusing on the time-slice distribution of the Population. However, these approaches can not be directly applied to analyzing the following cell lineage tree data. Owing to recent development of microfluidic devices, we can observe a lineage tree data, which describes a growing cell Population with hundreds of cells over hundreds generations. From the lineage tree data, we can obtain the information of mother-daughter relationship and inter-division interval (cell cycle), which can never be accessible in the time-slice observations. In order to analyze the lineage tree data, a pathwise approach have recently developed, instead of the conventional differential equation approaches. Main ingredients of this approach are two kinds of genealogical paths on a lineage tree: time-forward and time-backward (retrospective) paths. By using these two genealogical paths, we can evaluate the Stationary Population growth rate and selection strength that exists in the growing Population. In this presentation, we demonstrate the pathwise structure introduced above, under a multi-type age-structured Population dynamics (MTASP), which has an age-dependent cell replication and type transition. In the analysis of the MTASP, the large deviation technique for semi-Markov processes plays an important role. As a result, we find that the responses of the Stationary Population growth rate with respect to environmental changes can be calculated by the retrospective tracking on the cell lineage tree. Furthermore, we introduce a statistical method to infer the growth-related latent cell states by employing the pathwise structure on MTASP. To be more precise, we devise the inference method for the cell states based on the inter-division intervals data on the cell lineage tree. References [1] So Nakashima, Yuki Sughiyama and Tetsuya J. Kobayashi, arXiv:1806.00215 (2018). [2] Yuki Sughiyama, So Nakashima and Tetsuya J. Kobayashi, Phys. Rev. E 91, 012413 (2019). [3] Yuki Sughiayma and Tetsuya J. Kobayashi, J. Phys. A: Math. Theor. 51, 125001 (2018).

  • Fitness response relation of a multitype age-structured Population dynamics.
    Physical Review E, 2019
    Co-Authors: Yuki Sughiyama, So Nakashima, Tetsuya J. Kobayashi
    Abstract:

    We construct a pathwise formulation for a multitype age-structured Population dynamics, which involves an age-dependent cell replication and transition of gene- or phenotypes. By employing the formulation, we derive a variational representation of the Stationary Population growth rate; the representation comprises a tradeoff relation between growth effects and a single-cell intrinsic dynamics described by a semi-Markov process. This variational representation leads to a response relation of the Stationary Population growth rate, in which statistics on a retrospective history work as the response coefficients. These results contribute to predicting and controlling growing Populations based on experimentally observed cell-lineage information.

  • Pathwise analysis for a multi-type age-structured Population dynamics
    arXiv: Statistical Mechanics, 2018
    Co-Authors: Yuki Sughiyama, So Nakashima, Tetsuya J. Kobayashi
    Abstract:

    We show a pathwise formulation for a multi-type age-structured Population dynamics, which has an age-dependent cell replication and type transition. By employing the pathwise formulation, we find that the Stationary Population growth rate is determined by a variational principle that represents a trade off between growth effects and a single-cell intrinsic dynamics described by a semi-Markov process. Owing to this variational principle, a response relation of the Stationary Population growth rate is revealed. As a result, we find that the response coefficients can be evaluated by a statistics on a retrospective history.

Masaaki Suzuki - One of the best experts on this subject based on the ideXlab platform.

  • An experimental study of Stationary Population inversion in a cold recombining expanding helium plasma jet
    Plasma Sources Science and Technology, 1995
    Co-Authors: Hiroshi Akatsuka, Masaaki Suzuki
    Abstract:

    A Stationary cold recombining helium plasma is generated in an arc-heated magnetically trapped expanding plasma jet that was developed in the authors' laboratory. The plasma can be generated very stably and spectroscopic analysis is accomplished with sufficient accuracy. Population densities of the He I levels whose principal quantum numbers are 3-6 and 73D, 83D, 93D levels are observed spectroscopically. When the plasma comes downstream, the electron temperature and density become low and Population inversion is obtained between some level pairs, such as 41S-31P and 43P-3 3D. The degree of inversion is insufficient to be used for lasing. The electron temperature as found by Boltzmann plots of the higher states drops to about 0.2 eV in the downstream expansion. The electrons are cooled by contact with cold residual gas. The magnetic confinement of the plasma jet is adequate to cause large Population inversions without decreasing the electron density. The experimental results are explained in terms of a calculation based on a collisional radiative model including an optical thickness. The mechanisms of formation of Population inversions are discussed in terms of atomic processes.

  • Stationary Population inversion of hydrogen in an arc heated magnetically trapped expanding hydrogen helium plasma jet
    Physical Review E, 1994
    Co-Authors: Hiroshi Akatsuka, Masaaki Suzuki
    Abstract:

    A Stationary recombining hydrogen-helium mixed plasma is generated in the arc-heated magnetically trapped expanding plasma jet that was developed in the authors' laboratory. The plasma can be generated very stably and a spectroscopic analysis is accomplished with sufficient accuracy. Population densities of atomic hydrogen whose principal quantum number is 3--12 are observed spectroscopically. When the plasma comes downstream, the electron temperature becomes low and Population inversion is obtained between the level pairs 3-4, 3-5, and 4-5 in hydrogen atoms. The experimental results are explained very well by a calculation based on the collisional radiative model in which the hydrogen plasma is optically thin. The potential for cw lasing by H i is discussed in terms of atomic processes based on the experimental and numerical results.

Hiroshi Akatsuka - One of the best experts on this subject based on the ideXlab platform.

  • Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing
    AIP Conference Proceedings, 2005
    Co-Authors: Hiroshi Akatsuka, Katsuhiro Kano
    Abstract:

    An experiment of He gas‐contact for generating Population inversion in a recombining Ar plasma jet is carried out. Population inversion between Ar I excited states 5s′ → 4p′[1/2]1 and 5s′ → 4p[3/2]1,2, [5/2]2,3 is created by helium gas‐contact cooling of electrons, whereas it is not created without gas‐contact. Ar I lines 1.14 μm, 1.34 μm, and 1.09 μm are strongly enhnced due to the He gas cooling. It is experimentally found that helium gas contact effectively lowers electron temperature of the Ar plasma jet. The mechanisms giving rise to Population inversion are discussed in terms of atomic collisional processes of the recombining plasma. The experimental results of electron temperature and Population densities are discussed by simple numerical analysis which we previously developed. It is shown that the experimental results are well explained by our modeling quantitatively for the case without gas contact, except that the agreement of number densities of lower lying non‐LTE levels is qualitative for the...

  • An experimental study of Stationary Population inversion in a cold recombining expanding helium plasma jet
    Plasma Sources Science and Technology, 1995
    Co-Authors: Hiroshi Akatsuka, Masaaki Suzuki
    Abstract:

    A Stationary cold recombining helium plasma is generated in an arc-heated magnetically trapped expanding plasma jet that was developed in the authors' laboratory. The plasma can be generated very stably and spectroscopic analysis is accomplished with sufficient accuracy. Population densities of the He I levels whose principal quantum numbers are 3-6 and 73D, 83D, 93D levels are observed spectroscopically. When the plasma comes downstream, the electron temperature and density become low and Population inversion is obtained between some level pairs, such as 41S-31P and 43P-3 3D. The degree of inversion is insufficient to be used for lasing. The electron temperature as found by Boltzmann plots of the higher states drops to about 0.2 eV in the downstream expansion. The electrons are cooled by contact with cold residual gas. The magnetic confinement of the plasma jet is adequate to cause large Population inversions without decreasing the electron density. The experimental results are explained in terms of a calculation based on a collisional radiative model including an optical thickness. The mechanisms of formation of Population inversions are discussed in terms of atomic processes.

  • Stationary Population inversion of hydrogen in an arc heated magnetically trapped expanding hydrogen helium plasma jet
    Physical Review E, 1994
    Co-Authors: Hiroshi Akatsuka, Masaaki Suzuki
    Abstract:

    A Stationary recombining hydrogen-helium mixed plasma is generated in the arc-heated magnetically trapped expanding plasma jet that was developed in the authors' laboratory. The plasma can be generated very stably and a spectroscopic analysis is accomplished with sufficient accuracy. Population densities of atomic hydrogen whose principal quantum number is 3--12 are observed spectroscopically. When the plasma comes downstream, the electron temperature becomes low and Population inversion is obtained between the level pairs 3-4, 3-5, and 4-5 in hydrogen atoms. The experimental results are explained very well by a calculation based on the collisional radiative model in which the hydrogen plasma is optically thin. The potential for cw lasing by H i is discussed in terms of atomic processes based on the experimental and numerical results.