Marilyn Bishop | Virginia Commonwealth University (original) (raw)
Papers by Marilyn Bishop
Biochemistry, 1987
We have obtained a quantitative description of villin-nucleated actin polymerization in physiolog... more We have obtained a quantitative description of villin-nucleated actin polymerization in physiological salt by determining the concentrations of free villin (V), villin-actin monomer (VA), villin-actin dimer (VA2), and villin-actin oligomer (VAn). Over a range of actin-villin ratios from 0.1 to 20 we determined the concentration of actin-bound villin by measuring the low-intensity pyrenylactin fluorescence of the two terminal actins in each villin-actin polymer. (To this end we first showed that each villin-actin oligomer and polymer contains two low-intensity pyrenylactin molecules.) We determined the concentration of free villin using a calibrated cutting activity assay. The pattern of increase in bound villin together with the pattern of increase in high-intensity pyrenylactin fluorescence with increasing G-actin concentration indicated, first, that villin-actin monomers were not formed at detectable levels even at a 12-fold villin excess over actin. Second, there was no stoichiometric villin-actin dimer formation at actin-villin ratios of 2. Instead there was an equilibrium between free villin, VA2, and VAn. Defining K1 = [VA]/[V][A] and K2 = [VA2]/[VA][A], a good fit of the data was obtained with K1 much less than K2 and a value of K1K2 = Kv = 10(12)-10(13) M-2 = [VA2]/[V][A]2, i.e., 1/Kv1/2 = (0.3-1) X 10(-6) M. We have assumed here that the monomer binding constant of VA2 to form VA3 was equal to the monomer binding constant of pointed filament ends, K infinity = 1/c infinity, obtained as described below.(ABSTRACT TRUNCATED AT 250 WORDS)
Résumé. — Nous présentons la théorie et les évaluations numériques pour la section de la diffu-si... more Résumé. — Nous présentons la théorie et les évaluations numériques pour la section de la diffu-sion Raman en résonance avec les bandes d'absorption F des centres F dans les cristaux d'halogénure alcalin, caractérisés par un couplage d'interaction spin orbite X différent de zéro dans les états électro-niques excités. On montre que pour toutes les polarisations de la lumière incidente et diffusée les sections de la diffusion Raman pour les densités d'états phononiques ri", r j et rt sont toujours différentes de zéro. La théorie est appliquée aux deux cas particuliers des centres F dans les cristaux de Kl et CsF. Abstract. — We present the theory and the theoretical evaluations for the cross sections of the polarized Raman scattering in resonance with the F absorption bands of the F centres in alkali halides, characterized by a spin orbit interaction coupling coefficient A different from zero in the excited electronic states. We show that for all the polarizati...
: The theoretical results for the breakdown of the symmetry selection rules for defect-induced Ra... more : The theoretical results for the breakdown of the symmetry selection rules for defect-induced Raman scattering are presented in the case that (1) at least one of the p-like virtual electronic excited states has a strong spin orbit interaction and (2) the Jahn Teller active electron phonon interaction couplings evaluated on this excited state are different from zero. The evaluation of the effect presented here is performed for the Raman scattering from the F center in cesium halides. The author shows that all the densities of phonon states that transform according to the irreducible representations of the point group of the defect site are involved in determining every scattering process in which the incident and scattered light are linearly polarized.
Physical Review B
It is shown that the discrepancy between the magnitudes of the dips in the attenuated total refle... more It is shown that the discrepancy between the magnitudes of the dips in the attenuated total reflection (ATR) spectra associated with the surface exciton polariton prediction in earlier work by two of the present authors and those measured and calculated recently by Lagois and Fischer is due to the fact that our earlier
Le Journal de Physique Colloques
Nous présentons la théorie et les évaluations numériques pour la section de la diffusion Raman en... more Nous présentons la théorie et les évaluations numériques pour la section de la diffusion Raman en résonance avec les bandes d'absorption F des centres F dans les cristaux d'halogénure alcalin, caractérisés par un couplage d'interaction spin orbite X différent de zéro dans les états électroniques excités. On montre que pour toutes les polarisations de la lumière incidente et diffusée les sections de la diffusion Raman pour les densités d'états phononiques ri", rj et rt sont toujours différentes de zéro. La théorie est appliquée aux deux cas particuliers des centres F dans les cristaux de Kl et CsF.
Solid State Communications, 1976
We present theoretical results for the temperature dependent breakdown of the Raman scattering se... more We present theoretical results for the temperature dependent breakdown of the Raman scattering selection rules induced by a dynamical lowering of the site symmetry in systems that exhibit the dynamic Jahn-Teller effect in the excited electronic states.
Solid State Communications, 1973
Journal of Biological …, 1986
Jennifer NorthropS, Annemarie Weber$#, Mark S . Moosekern, Clara Franzini-Armstrong$, Marilyn F. ... more Jennifer NorthropS, Annemarie Weber$#, Mark S . Moosekern, Clara Franzini-Armstrong$, Marilyn F. Bishop[[, George R. Dubyak$, Marianne Tucker$, and Terrence P. Walsh$** From the $Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, the ( ...
Biophysical Journal, 1989
We show that the commonly used Rayleigh-Debye method for calculating light scattering can lead to... more We show that the commonly used Rayleigh-Debye method for calculating light scattering can lead to significant errors when used for describing scattering from dilute solutions of long rigid polymers, errors that can be overcome by use of the easily applied Shifrin approximation. In order to show the extent of the discrepancies between the two methods, we have performed calculations at normal incidence both for polarized and unpolarized incident light with the scattering intensity determined as a function of polarization angle and of scattering DiupI1ywcI a,iopnysicai ocew
Biophysical Journal, 1984
We present a perturbation method for analyzing nucleation-controlled polymerization augmented by ... more We present a perturbation method for analyzing nucleation-controlled polymerization augmented by a secondary pathway for polymer growth. With this method, the solution to the kinetic equations assumes a simple analytic closed form that can easily be used in fitting data. So long as the formation of polymers by the secondary pathway depends linearly on the concentration of monomers polymerized, the form of the solutions is the same. This permits the analysis of augmented growth models with a minimum number of modeling assumptions, and thus makes it readily possible to distinguish between a variety of secondary processes (heterogeneous nucleation, lateral growth, and fragmentation). In addition, the parameters of the homogeneous process, such as the homogeneous nucleus size, can be determined independent of the nature of the secondary mechanism. We describe applications of this method to the polymerization of actin, collagen, and sickle hemoglobin. We present an extensive analysis of data on actin polymerization (Wegner, A., and P. Savko, 1982, Biochemistry, 21:1909-1913) to illustrate the use of the method. Although our conclusions generally agree with theirs, we find that lateral growth describes the secondary pathway better than the fragmentation model originally proposed. We also show how this method can be used to study the degree of polymerization, the parentage of polymers, and the behavior of polymers in cycling experiments.
Physical Review B
Surface polaritons associated with localized modes in crystals are investigated theoretically by ... more Surface polaritons associated with localized modes in crystals are investigated theoretically by considering the case of CaF, :H. The dielectric constant is calculated using a simple model that includes damped oscillators for both the tansverse-optical mode of the pure crystal and the localized mode, for two temperatures, 80 and 300'K. We find that the surface polaritons of the impurities are Zenneck modes, while those of the pure crystal are lossy Fano modes. The dispersion relation for real wave vector and complex frequency is given, and the determination of the dispersion relation by the method of attenuated total reflection (ATR) is calculated. We find that the damping in this system is sufficient that one must consider the ratio of pto s-polarized reflectivities in the ATR spectra in order to determine the localized-mode surface-polariton dispersion relation. Any elementary excitation in a solid, liquid, or gas that is electric dipole or magnetic dipole active, in the sense that it contributes a pole (real or complex) to the dielectric tensor or magnetic
Physical Review B
We consider energy flow in a semi-infinite spatially dispersive absorbing dielectric bounded by v... more We consider energy flow in a semi-infinite spatially dispersive absorbing dielectric bounded by vacuum, on which light is incident from the vacuum, with the direction of propagation normal to the surface. While the total energy flux in the vacuum is given by its electromagnetic Poynting vector, the total energy flux in the crystal is given by the sum of the electromagnetic Poynting vector and a mechanical Poynting vector, which arises from the energy transported by the excitations in the medium. We consider two models, the first of which is a semi-infinite medium in the dielectric approximation, which consists of assuming that the nonlocal dielectric function of the semi-infinite crystal is that of the infinitely extended medium, so that the surface of the medium enters the theory only through the restriction of the coordinates normal to the surface to the halfspace occupied by the medium. We show that this model fails to conserve energy in the sense that the surface acts as a source of energy, because for this model the mechanical Poynting vector is positive on the surface, while the electromagnetic Poynting vector is continuous across the surface. The second model considered includes the effects of a surface in a phenomenological way in the dielectric function. We find that for this model energy is conserved; that is, the surface acts neither as a source nor sink of energy. Finally, we find that for normal incidence, when the additional boundary condition for a given model of a spatially dispersive dielectric medium may be expressed in terms of the polarization %(z) associated with the dipole-active excitation in the medium as [a%(z)+ P dP(z)/dz], 0 = 0, the coefficients a and P determine whether or not the surface is a source or sink of energy. The mechanical Poynting vector is proportional to Im(a/P), so that when this quantity vanishes, the surface is neither a source nor sink of energy, but when it is nonzero, the surface is either a source or sink of energy, depending on the sign of the other constants entering into the expression for the mechanical Poynting vector.
OVERHAUSER:ANOMALOUS O-BK, 2010
OVERHAUSER:ANOMALOUS O-BK, 2010
Physical Review B, 1981
Scattering of electrons by phasons, the collective excitations of an incommensurate charge-densit... more Scattering of electrons by phasons, the collective excitations of an incommensurate charge-density wave (CDW), is presented as a new mechanism in the low-temperature resistivity of potassium. It is shown to provide an explanation for recent precision measurements in potassium between 0.38 and 1.3 K, where conventional mechanisms, such as electron-electron scattering, fail. With this theory, it is possible to explain the shape of the measured resistivity curves, the magnitude of the temperature-dependent part of the resistivity, and the sample dependence. The sample dependence is explained since the measured electron-phason resistivity, which is much larger along the CDW wave vector Q--> than perpendicular to it, depends on the Q-->-domain structure of a particular sample. Fitting this theory to these experiments yields the value for the phason temperature Thetaphi=3.25 K and an approximate range of the anisotropy of the phason spectrum, 7.7<~(1eta)<~9.7.. Further resistivity measurements at ultralow temperatures are needed to test the hypothesis of electron-phason scattering, and, if this mechanism continues to show promise, to provide more accurate estimates for the phason parameters.
Biochemistry, 1987
We have obtained a quantitative description of villin-nucleated actin polymerization in physiolog... more We have obtained a quantitative description of villin-nucleated actin polymerization in physiological salt by determining the concentrations of free villin (V), villin-actin monomer (VA), villin-actin dimer (VA2), and villin-actin oligomer (VAn). Over a range of actin-villin ratios from 0.1 to 20 we determined the concentration of actin-bound villin by measuring the low-intensity pyrenylactin fluorescence of the two terminal actins in each villin-actin polymer. (To this end we first showed that each villin-actin oligomer and polymer contains two low-intensity pyrenylactin molecules.) We determined the concentration of free villin using a calibrated cutting activity assay. The pattern of increase in bound villin together with the pattern of increase in high-intensity pyrenylactin fluorescence with increasing G-actin concentration indicated, first, that villin-actin monomers were not formed at detectable levels even at a 12-fold villin excess over actin. Second, there was no stoichiometric villin-actin dimer formation at actin-villin ratios of 2. Instead there was an equilibrium between free villin, VA2, and VAn. Defining K1 = [VA]/[V][A] and K2 = [VA2]/[VA][A], a good fit of the data was obtained with K1 much less than K2 and a value of K1K2 = Kv = 10(12)-10(13) M-2 = [VA2]/[V][A]2, i.e., 1/Kv1/2 = (0.3-1) X 10(-6) M. We have assumed here that the monomer binding constant of VA2 to form VA3 was equal to the monomer binding constant of pointed filament ends, K infinity = 1/c infinity, obtained as described below.(ABSTRACT TRUNCATED AT 250 WORDS)
Résumé. — Nous présentons la théorie et les évaluations numériques pour la section de la diffu-si... more Résumé. — Nous présentons la théorie et les évaluations numériques pour la section de la diffu-sion Raman en résonance avec les bandes d'absorption F des centres F dans les cristaux d'halogénure alcalin, caractérisés par un couplage d'interaction spin orbite X différent de zéro dans les états électro-niques excités. On montre que pour toutes les polarisations de la lumière incidente et diffusée les sections de la diffusion Raman pour les densités d'états phononiques ri", r j et rt sont toujours différentes de zéro. La théorie est appliquée aux deux cas particuliers des centres F dans les cristaux de Kl et CsF. Abstract. — We present the theory and the theoretical evaluations for the cross sections of the polarized Raman scattering in resonance with the F absorption bands of the F centres in alkali halides, characterized by a spin orbit interaction coupling coefficient A different from zero in the excited electronic states. We show that for all the polarizati...
: The theoretical results for the breakdown of the symmetry selection rules for defect-induced Ra... more : The theoretical results for the breakdown of the symmetry selection rules for defect-induced Raman scattering are presented in the case that (1) at least one of the p-like virtual electronic excited states has a strong spin orbit interaction and (2) the Jahn Teller active electron phonon interaction couplings evaluated on this excited state are different from zero. The evaluation of the effect presented here is performed for the Raman scattering from the F center in cesium halides. The author shows that all the densities of phonon states that transform according to the irreducible representations of the point group of the defect site are involved in determining every scattering process in which the incident and scattered light are linearly polarized.
Physical Review B
It is shown that the discrepancy between the magnitudes of the dips in the attenuated total refle... more It is shown that the discrepancy between the magnitudes of the dips in the attenuated total reflection (ATR) spectra associated with the surface exciton polariton prediction in earlier work by two of the present authors and those measured and calculated recently by Lagois and Fischer is due to the fact that our earlier
Le Journal de Physique Colloques
Nous présentons la théorie et les évaluations numériques pour la section de la diffusion Raman en... more Nous présentons la théorie et les évaluations numériques pour la section de la diffusion Raman en résonance avec les bandes d'absorption F des centres F dans les cristaux d'halogénure alcalin, caractérisés par un couplage d'interaction spin orbite X différent de zéro dans les états électroniques excités. On montre que pour toutes les polarisations de la lumière incidente et diffusée les sections de la diffusion Raman pour les densités d'états phononiques ri", rj et rt sont toujours différentes de zéro. La théorie est appliquée aux deux cas particuliers des centres F dans les cristaux de Kl et CsF.
Solid State Communications, 1976
We present theoretical results for the temperature dependent breakdown of the Raman scattering se... more We present theoretical results for the temperature dependent breakdown of the Raman scattering selection rules induced by a dynamical lowering of the site symmetry in systems that exhibit the dynamic Jahn-Teller effect in the excited electronic states.
Solid State Communications, 1973
Journal of Biological …, 1986
Jennifer NorthropS, Annemarie Weber$#, Mark S . Moosekern, Clara Franzini-Armstrong$, Marilyn F. ... more Jennifer NorthropS, Annemarie Weber$#, Mark S . Moosekern, Clara Franzini-Armstrong$, Marilyn F. Bishop[[, George R. Dubyak$, Marianne Tucker$, and Terrence P. Walsh$** From the $Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, the ( ...
Biophysical Journal, 1989
We show that the commonly used Rayleigh-Debye method for calculating light scattering can lead to... more We show that the commonly used Rayleigh-Debye method for calculating light scattering can lead to significant errors when used for describing scattering from dilute solutions of long rigid polymers, errors that can be overcome by use of the easily applied Shifrin approximation. In order to show the extent of the discrepancies between the two methods, we have performed calculations at normal incidence both for polarized and unpolarized incident light with the scattering intensity determined as a function of polarization angle and of scattering DiupI1ywcI a,iopnysicai ocew
Biophysical Journal, 1984
We present a perturbation method for analyzing nucleation-controlled polymerization augmented by ... more We present a perturbation method for analyzing nucleation-controlled polymerization augmented by a secondary pathway for polymer growth. With this method, the solution to the kinetic equations assumes a simple analytic closed form that can easily be used in fitting data. So long as the formation of polymers by the secondary pathway depends linearly on the concentration of monomers polymerized, the form of the solutions is the same. This permits the analysis of augmented growth models with a minimum number of modeling assumptions, and thus makes it readily possible to distinguish between a variety of secondary processes (heterogeneous nucleation, lateral growth, and fragmentation). In addition, the parameters of the homogeneous process, such as the homogeneous nucleus size, can be determined independent of the nature of the secondary mechanism. We describe applications of this method to the polymerization of actin, collagen, and sickle hemoglobin. We present an extensive analysis of data on actin polymerization (Wegner, A., and P. Savko, 1982, Biochemistry, 21:1909-1913) to illustrate the use of the method. Although our conclusions generally agree with theirs, we find that lateral growth describes the secondary pathway better than the fragmentation model originally proposed. We also show how this method can be used to study the degree of polymerization, the parentage of polymers, and the behavior of polymers in cycling experiments.
Physical Review B
Surface polaritons associated with localized modes in crystals are investigated theoretically by ... more Surface polaritons associated with localized modes in crystals are investigated theoretically by considering the case of CaF, :H. The dielectric constant is calculated using a simple model that includes damped oscillators for both the tansverse-optical mode of the pure crystal and the localized mode, for two temperatures, 80 and 300'K. We find that the surface polaritons of the impurities are Zenneck modes, while those of the pure crystal are lossy Fano modes. The dispersion relation for real wave vector and complex frequency is given, and the determination of the dispersion relation by the method of attenuated total reflection (ATR) is calculated. We find that the damping in this system is sufficient that one must consider the ratio of pto s-polarized reflectivities in the ATR spectra in order to determine the localized-mode surface-polariton dispersion relation. Any elementary excitation in a solid, liquid, or gas that is electric dipole or magnetic dipole active, in the sense that it contributes a pole (real or complex) to the dielectric tensor or magnetic
Physical Review B
We consider energy flow in a semi-infinite spatially dispersive absorbing dielectric bounded by v... more We consider energy flow in a semi-infinite spatially dispersive absorbing dielectric bounded by vacuum, on which light is incident from the vacuum, with the direction of propagation normal to the surface. While the total energy flux in the vacuum is given by its electromagnetic Poynting vector, the total energy flux in the crystal is given by the sum of the electromagnetic Poynting vector and a mechanical Poynting vector, which arises from the energy transported by the excitations in the medium. We consider two models, the first of which is a semi-infinite medium in the dielectric approximation, which consists of assuming that the nonlocal dielectric function of the semi-infinite crystal is that of the infinitely extended medium, so that the surface of the medium enters the theory only through the restriction of the coordinates normal to the surface to the halfspace occupied by the medium. We show that this model fails to conserve energy in the sense that the surface acts as a source of energy, because for this model the mechanical Poynting vector is positive on the surface, while the electromagnetic Poynting vector is continuous across the surface. The second model considered includes the effects of a surface in a phenomenological way in the dielectric function. We find that for this model energy is conserved; that is, the surface acts neither as a source nor sink of energy. Finally, we find that for normal incidence, when the additional boundary condition for a given model of a spatially dispersive dielectric medium may be expressed in terms of the polarization %(z) associated with the dipole-active excitation in the medium as [a%(z)+ P dP(z)/dz], 0 = 0, the coefficients a and P determine whether or not the surface is a source or sink of energy. The mechanical Poynting vector is proportional to Im(a/P), so that when this quantity vanishes, the surface is neither a source nor sink of energy, but when it is nonzero, the surface is either a source or sink of energy, depending on the sign of the other constants entering into the expression for the mechanical Poynting vector.
OVERHAUSER:ANOMALOUS O-BK, 2010
OVERHAUSER:ANOMALOUS O-BK, 2010
Physical Review B, 1981
Scattering of electrons by phasons, the collective excitations of an incommensurate charge-densit... more Scattering of electrons by phasons, the collective excitations of an incommensurate charge-density wave (CDW), is presented as a new mechanism in the low-temperature resistivity of potassium. It is shown to provide an explanation for recent precision measurements in potassium between 0.38 and 1.3 K, where conventional mechanisms, such as electron-electron scattering, fail. With this theory, it is possible to explain the shape of the measured resistivity curves, the magnitude of the temperature-dependent part of the resistivity, and the sample dependence. The sample dependence is explained since the measured electron-phason resistivity, which is much larger along the CDW wave vector Q--> than perpendicular to it, depends on the Q-->-domain structure of a particular sample. Fitting this theory to these experiments yields the value for the phason temperature Thetaphi=3.25 K and an approximate range of the anisotropy of the phason spectrum, 7.7<~(1eta)<~9.7.. Further resistivity measurements at ultralow temperatures are needed to test the hypothesis of electron-phason scattering, and, if this mechanism continues to show promise, to provide more accurate estimates for the phason parameters.