Jack Merrin - Academia.edu (original) (raw)

Papers by Jack Merrin

Physica B: Condensed Matter, 2000

We discuss the use of the Kubo Golden rule (KGR) in the derivation of new muon polarization funct... more We discuss the use of the Kubo Golden rule (KGR) in the derivation of new muon polarization functions for arbitrary static field distributions in both zero (ZF) and longitudinal (LF) applied fields. ZF/LF muon spin relaxation measurements in spin-ladder system Sr(Cu1−xZnx)2O3 are reported, with observations of dilute moment freezing for x≲0.008 and dense moment freezing for x≳0.008. In neither the dilute nor the dense case do the data conform to classic muon polarization functions. Using the KGR we derive new muon polarization functions to deal with both of these cases. The dilute case assumes dilute moments with a dense moment background, while the dense case assumes an exponential distribution of fields. Simulation of this system is consistent with an exponential distribution of fields.

Physical review. B, Condensed matter

We have studied the magnetic properties of the S=1/2 quasi-one-dimensional Heisenberg antiferroma... more We have studied the magnetic properties of the S=1/2 quasi-one-dimensional Heisenberg antiferromagnet SrCuO2, which has zigzag chains of Cu2+ ions. We have observed a static magnetic ordering below T-c similar to 2 K. The weak internal field in the muon spin relaxation spectra and the absence of the magnetic Bragg peaks below T-c suggest that the Cu2+ moments are largely reduced probably due to the quantum fluctuation. The remarkable suppression of the ordering temperature (kT(c)/J(2)=1.1x10(-3)), where J(2) is the dominant exchange constant, probably originates from the combined effects of quantum fluctuation and frustration.

Physical Review B, 1997

... SrCuO2 M. Matsuda and K. Katsumata The Institute of Physical and Chemical Research (RIKEN), W... more ... SrCuO2 M. Matsuda and K. Katsumata The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan KM Kojima, M. Larkin, GM Luke, J ... This work was partially supported by the NEDO International Joint Research Grant, by the NSF under Grant No. ...

Physical Review B, 1998

... 4 GM Luke, K. Kojima, M. Larkin, J. Merrin, B. Nachumi, YJ Uemura, Y. Nakamura, S. Uchida, an... more ... 4 GM Luke, K. Kojima, M. Larkin, J. Merrin, B. Nachumi, YJ Uemura, Y. Nakamura, S. Uchida, and M. Crawford, Hyperfine Interact. 105, 113 1997 . 5 F. Borsa, P. Carretta, JN Cho, FC Chou, Q. Nu, DC Johnston, A. Lascialfari, DR Torgeson, RJ Gooding, NM Salem, and KJE Vos ...

We report muSR measurements confirming the microscopic coexistence (rather than phase separation)... more We report muSR measurements confirming the microscopic coexistence (rather than phase separation) of superconductivity and novel stripe magnetic order in the 214 cuprate series with dopant concentrations x=0.125-0.15. In addition, we present the results of calculations of the muon site and the ordered moment size. The stripe phase is compared to the magnetic 3-leg ladder cuprate and other quasi 1-dimensional

ABSTRACT Living matter is a non-equilibrium system in which many components work in parallel to p... more ABSTRACT Living matter is a non-equilibrium system in which many components work in parallel to perpetuate themselves through a fluctuating environment. Physiological states or functionalities revealed by a particular environment are called phenotypes. Transitions between phenotypes may occur either spontaneously or via interaction with the environment. Even in the same environment, genetically identical bacteria can exhibit different phenotypes of a continuous or discrete nature. In this thesis, we pursued three lines of investigation into discrete phenotypic heterogeneity in bacterial populations: the quantitative characterization of the so-called bacterial persistence, a theoretical model of phenotypic switching based on those measurements, and the design of artificial genetic networks which implement this model. Persistence is the phenotype of a subpopulation of bacteria with a reduced sensitivity to antibiotics. We developed a microfluidic apparatus, which allowed us to monitor the growth rates of individual cells while applying repeated cycles of antibiotic treatments. We were able to identify distinct phenotypes (normal and persistent) and characterize the stochastic transitions between them. We also found that phenotypic heterogeneity was present prior to any environmental cue such as antibiotic exposure. Motivated by the experiments with persisters, we formulated a theoretical model describing the dynamic behavior of several discrete phenotypes in a periodically varying environment. This theoretical framework allowed us to quantitatively predict the fitness of dynamic populations and to compare survival strategies according to environmental time-symmetries. These calculations suggested that persistence is a strategy used by bacterial populations to adapt to fluctuating environments. Knowledge of the phenotypic transition rates for persistence may provide statistical information about the typical environments of bacteria. We also describe a design of artificial genetic networks that would implement a more general theoretical model of phenotypic switching. We will use a new cloning strategy in order to systematically assemble a large number of genetic features, such as site-specific recombination components from the R64 plasmid, which invert several coexisting DNA segments. The inversion of these segments would lead to discrete phenotypic transitions inside a living cell. These artificial phenotypic switches can be controlled precisely in experiments and may serve as a benchmark for their natural counterparts.

We have used the muon spin relaxation technique to study magnetic properties of the hole dopeable... more We have used the muon spin relaxation technique to study magnetic properties of the hole dopeable hybrid two leg ladder/linear chain compound (La,Sr,Ca)_14Cu_24O_41. Hole doping was varied from 0 to 6 holes per formula unit in La_6-xSr_xCa_8Cu_24O_41, x=0,1,2,4,6 and effective (chemical) pressure was varied at maximal hole doping in Sr_14-yCa_yCu_24O_41, y=8,11. For 0 doped holes T_N=14K and the average interal

Physica B: Condensed Matter, 2000

Proceedings of the National Academy of Sciences, 2011

Physical Review Letters, 1996

Physical Review Letters, 1997

... KM Kojima,1,* Y. Fudamoto,1 M. Larkin,1 GM Luke,1 J. Merrin,1 B. Nachumi,1 YJ Uemura,1 M. Has... more ... KM Kojima,1,* Y. Fudamoto,1 M. Larkin,1 GM Luke,1 J. Merrin,1 B. Nachumi,1 YJ Uemura,1 M. Hase,2,† Y. Sasago,2 K. Uchinokura,2 Y. Ajiro,3,‡ A. Revcolevschi,4 and J.-P. Renard5 1Department of Physics, Columbia University, New York, New York 10027 2Department of ...

Physical Review Letters, 1997

Physica B: Condensed Matter, 2000

We discuss the use of the Kubo Golden rule (KGR) in the derivation of new muon polarization funct... more We discuss the use of the Kubo Golden rule (KGR) in the derivation of new muon polarization functions for arbitrary static field distributions in both zero (ZF) and longitudinal (LF) applied fields. ZF/LF muon spin relaxation measurements in spin-ladder system Sr(Cu1−xZnx)2O3 are reported, with observations of dilute moment freezing for x≲0.008 and dense moment freezing for x≳0.008. In neither the dilute nor the dense case do the data conform to classic muon polarization functions. Using the KGR we derive new muon polarization functions to deal with both of these cases. The dilute case assumes dilute moments with a dense moment background, while the dense case assumes an exponential distribution of fields. Simulation of this system is consistent with an exponential distribution of fields.

Physical review. B, Condensed matter

We have studied the magnetic properties of the S=1/2 quasi-one-dimensional Heisenberg antiferroma... more We have studied the magnetic properties of the S=1/2 quasi-one-dimensional Heisenberg antiferromagnet SrCuO2, which has zigzag chains of Cu2+ ions. We have observed a static magnetic ordering below T-c similar to 2 K. The weak internal field in the muon spin relaxation spectra and the absence of the magnetic Bragg peaks below T-c suggest that the Cu2+ moments are largely reduced probably due to the quantum fluctuation. The remarkable suppression of the ordering temperature (kT(c)/J(2)=1.1x10(-3)), where J(2) is the dominant exchange constant, probably originates from the combined effects of quantum fluctuation and frustration.

Physical Review B, 1997

... SrCuO2 M. Matsuda and K. Katsumata The Institute of Physical and Chemical Research (RIKEN), W... more ... SrCuO2 M. Matsuda and K. Katsumata The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan KM Kojima, M. Larkin, GM Luke, J ... This work was partially supported by the NEDO International Joint Research Grant, by the NSF under Grant No. ...

Physical Review B, 1998

... 4 GM Luke, K. Kojima, M. Larkin, J. Merrin, B. Nachumi, YJ Uemura, Y. Nakamura, S. Uchida, an... more ... 4 GM Luke, K. Kojima, M. Larkin, J. Merrin, B. Nachumi, YJ Uemura, Y. Nakamura, S. Uchida, and M. Crawford, Hyperfine Interact. 105, 113 1997 . 5 F. Borsa, P. Carretta, JN Cho, FC Chou, Q. Nu, DC Johnston, A. Lascialfari, DR Torgeson, RJ Gooding, NM Salem, and KJE Vos ...

We report muSR measurements confirming the microscopic coexistence (rather than phase separation)... more We report muSR measurements confirming the microscopic coexistence (rather than phase separation) of superconductivity and novel stripe magnetic order in the 214 cuprate series with dopant concentrations x=0.125-0.15. In addition, we present the results of calculations of the muon site and the ordered moment size. The stripe phase is compared to the magnetic 3-leg ladder cuprate and other quasi 1-dimensional

ABSTRACT Living matter is a non-equilibrium system in which many components work in parallel to p... more ABSTRACT Living matter is a non-equilibrium system in which many components work in parallel to perpetuate themselves through a fluctuating environment. Physiological states or functionalities revealed by a particular environment are called phenotypes. Transitions between phenotypes may occur either spontaneously or via interaction with the environment. Even in the same environment, genetically identical bacteria can exhibit different phenotypes of a continuous or discrete nature. In this thesis, we pursued three lines of investigation into discrete phenotypic heterogeneity in bacterial populations: the quantitative characterization of the so-called bacterial persistence, a theoretical model of phenotypic switching based on those measurements, and the design of artificial genetic networks which implement this model. Persistence is the phenotype of a subpopulation of bacteria with a reduced sensitivity to antibiotics. We developed a microfluidic apparatus, which allowed us to monitor the growth rates of individual cells while applying repeated cycles of antibiotic treatments. We were able to identify distinct phenotypes (normal and persistent) and characterize the stochastic transitions between them. We also found that phenotypic heterogeneity was present prior to any environmental cue such as antibiotic exposure. Motivated by the experiments with persisters, we formulated a theoretical model describing the dynamic behavior of several discrete phenotypes in a periodically varying environment. This theoretical framework allowed us to quantitatively predict the fitness of dynamic populations and to compare survival strategies according to environmental time-symmetries. These calculations suggested that persistence is a strategy used by bacterial populations to adapt to fluctuating environments. Knowledge of the phenotypic transition rates for persistence may provide statistical information about the typical environments of bacteria. We also describe a design of artificial genetic networks that would implement a more general theoretical model of phenotypic switching. We will use a new cloning strategy in order to systematically assemble a large number of genetic features, such as site-specific recombination components from the R64 plasmid, which invert several coexisting DNA segments. The inversion of these segments would lead to discrete phenotypic transitions inside a living cell. These artificial phenotypic switches can be controlled precisely in experiments and may serve as a benchmark for their natural counterparts.

We have used the muon spin relaxation technique to study magnetic properties of the hole dopeable... more We have used the muon spin relaxation technique to study magnetic properties of the hole dopeable hybrid two leg ladder/linear chain compound (La,Sr,Ca)_14Cu_24O_41. Hole doping was varied from 0 to 6 holes per formula unit in La_6-xSr_xCa_8Cu_24O_41, x=0,1,2,4,6 and effective (chemical) pressure was varied at maximal hole doping in Sr_14-yCa_yCu_24O_41, y=8,11. For 0 doped holes T_N=14K and the average interal

Physica B: Condensed Matter, 2000

Proceedings of the National Academy of Sciences, 2011

Physical Review Letters, 1996

Physical Review Letters, 1997

... KM Kojima,1,* Y. Fudamoto,1 M. Larkin,1 GM Luke,1 J. Merrin,1 B. Nachumi,1 YJ Uemura,1 M. Has... more ... KM Kojima,1,* Y. Fudamoto,1 M. Larkin,1 GM Luke,1 J. Merrin,1 B. Nachumi,1 YJ Uemura,1 M. Hase,2,† Y. Sasago,2 K. Uchinokura,2 Y. Ajiro,3,‡ A. Revcolevschi,4 and J.-P. Renard5 1Department of Physics, Columbia University, New York, New York 10027 2Department of ...

Physical Review Letters, 1997