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Anthony J. Baucum - One of the best experts on this subject based on the ideXlab platform.
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Mechanisms and Consequences of Dopamine Depletion-Induced Attenuation of the Spinophilin/Neurofilament Medium Interaction.
Neural plasticity, 2017Co-Authors: Andrew C. Hiday, Asma B. Salek, Cameron W. Morris, Michael C. Edler, Morrent Thang, Tyler J. Rentz, Kristie L. Rose, Lisa M. Jones, Anthony J. BaucumAbstract:Signaling changes that occur in the striatum following the loss of dopamine neurons in the Parkinson disease (PD) are poorly understood. While increases in the activity of kinases and decreases in the activity of phosphatases have been observed, the specific consequences of these changes are less well understood. Phosphatases, such as protein phosphatase 1 (PP1), are highly promiscuous and obtain substrate selectivity via targeting proteins. Spinophilin is the major PP1-targeting protein enriched in the postsynaptic density of striatal dendritic spines. Spinophilin association with PP1 is increased concurrent with decreases in PP1 activity in an animal model of PD. Using proteomic-based approaches, we observed dopamine depletion-induced decreases in spinophilin binding to multiple protein classes in the striatum. Specifically, there was a decrease in the association of spinophilin with neurofilament Medium (NF-M) in dopamine-depleted striatum. Using a heterologous cell line, we determined that spinophilin binding to NF-M required overexpression of the catalytic subunit of protein kinase A and was decreased by cyclin-dependent protein kinase 5. Functionally, we demonstrate that spinophilin can decrease NF-M phosphorylation. Our data determine mechanisms that regulate, and putative consequences of, pathological changes in the association of spinophilin with NF-M that are observed in animal models of PD.
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mechanisms and consequences of dopamine depletion induced attenuation of the spinophilin neurofilament Medium Interaction
Neural Plasticity, 2017Co-Authors: Andrew C. Hiday, Asma B. Salek, Anthony J. Baucum, Cameron W. Morris, Michael C. Edler, Morrent Thang, Tyler J. Rentz, Kristie L. Rose, Lisa M. JonesAbstract:Signaling changes that occur in the striatum following the loss of dopamine neurons in the Parkinson disease (PD) are poorly understood. While increases in the activity of kinases and decreases in the activity of phosphatases have been observed, the specific consequences of these changes are less well understood. Phosphatases, such as protein phosphatase 1 (PP1), are highly promiscuous and obtain substrate selectivity via targeting proteins. Spinophilin is the major PP1-targeting protein enriched in the postsynaptic density of striatal dendritic spines. Spinophilin association with PP1 is increased concurrent with decreases in PP1 activity in an animal model of PD. Using proteomic-based approaches, we observed dopamine depletion-induced decreases in spinophilin binding to multiple protein classes in the striatum. Specifically, there was a decrease in the association of spinophilin with neurofilament Medium (NF-M) in dopamine-depleted striatum. Using a heterologous cell line, we determined that spinophilin binding to NF-M required overexpression of the catalytic subunit of protein kinase A and was decreased by cyclin-dependent protein kinase 5. Functionally, we demonstrate that spinophilin can decrease NF-M phosphorylation. Our data determine mechanisms that regulate, and putative consequences of, pathological changes in the association of spinophilin with NF-M that are observed in animal models of PD.
N V Pogorelov - One of the best experts on this subject based on the ideXlab platform.
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physics of the solar wind local interstellar Medium Interaction role of magnetic fields
Space Science Reviews, 2009Co-Authors: G P Zank, H Washimi, J Heerikhuisen, V Florinski, N V Pogorelov, S N Borovikov, I A Kryukov, Hansreinhard MullerAbstract:The Interaction of the solar wind with the local interstellar Medium is characterized by the self-consistent coupling of solar wind plasma, both upstream and downstream of the heliospheric termination shock, the interstellar plasma, and the neutral atom component of interstellar and solar wind origin. The complex coupling results in the creation of new plasma components (pickup ions), turbulence, and anomalous cosmic rays, and new populations of neutral atoms and their coupling can lead to energetic neutral atoms that can be detected at 1 AU. In this review, we discuss the Interaction and coupling of global sized structures (the heliospheric boundary regions) and kinetic physics (the distributions that are responsible for the creation of energetic neutral atoms) based on models that have been developed by the University of Alabama in Huntsville group.
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modeling kinetic neutral atoms in the solar wind interstellar Medium Interaction region
ASPC, 2008Co-Authors: J Heerikhuisen, V Florinski, N V Pogorelov, G P ZankAbstract:The solar wind is a continuous stream of plasma flowing out from the Sun. The flow of interstellar Medium plasma diverts the solar wind and creates a teardrop shaped heliosphere. Although the plasma flows do not mix, neutral atoms of interstellar origin penetrate deep into the solar wind, unhindered by magnetic field fields. Charge-exchange couples these neutral atoms to the ionized plasma, creating a complicated neutral atom distribution function which encapsulates aspects of the cold interstellar, fast solar wind and hot heliosheath parent plasma populations. Due to the large mean free paths, we must model the neutral atoms kinetically. In this paper we will present an overview of the kinetic neutral atom model and its coupling to a 3D MHD-plasma code. We will indicate some key results regarding the neutral distribution function and how this compares to neutral fluid models. Finally we show how this model can be used to predict and understand energetic neutral atom skymaps which will be a key part of the upcoming IBEX mission data.
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mhd boltzmann simulations of the solar wind interstellar Medium Interaction
ASPC, 2006Co-Authors: J Heerikhuisen, V Florinski, G P Zank, N V PogorelovAbstract:The supersonic solar wind carves out a bubble within the local interstellar cloud. The Sun is moving supersonically with respect to the cloud, giving rise to a solar wind termination shock, an interstellar bow shock and a tangential discontinuity called the heliopause which separates the solar and interstellar plasmas. The local interstellar Medium is a partially ionized plasma, being comprised predominantly of neutral hydrogen gas. While the ionized components are constrained by magnetic fields, the neutral atoms travel large distances unimpeded, their dominant Interaction being charge exchange with a plasma proton. Due to these large mean free paths the neutral hydrogen component needs to be modeled kinetically rather than hydrodynamically. In this paper we present some background to the solar wind-interstellar Medium Interaction problem and some details of the Monte Carlo algorithm used to model neutral atom trajectories. We will then compare kinetic and hydrodynamic models for hydrogen atoms in the heliosphere and present some latest predictions for neutral atom fluxes which IBEX will measure.
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nonevolutionary mhd shocks in the solar wind and interstellar Medium Interaction
A&A, 2000Co-Authors: N V Pogorelov, Takuya MatsudaAbstract:We present the study of the solar wind Interaction with the super-Alfv´ enic magnetized interstellar Medium in the controversial case when fast magnetosonic shocks are nonevo- lutionary, while admissible switch-on shocks cannot exist due to geometrical reasons. The flow behaviour and the accom- panying shock configuration are investigated both in the two- dimensional axisymmetric and 2.5-dimensional, that is, permit- ting rotation around the symmetry axis, statements. General questions of the origin of nonevolutionary MHD shocks are discussed.
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application of numerical methods to modeling the stellar wind and interstellar Medium Interaction
arXiv: Geophysics, 1998Co-Authors: N V Pogorelov, Takuya MatsudaAbstract:We present a review of the application of numerical methods to solve the problem of the stellar/solar wind with the local interstellar Medium. Most of approaches described are developed by the authors. They include both purely gas dynamic and magnetohydrodynamic methods. Some attention is given to the influence of the neutral component of the interstellar Medium on the flow structure. Far-field boundary conditions are formulated which are usually required in astrophyscal application owing to the extremely large length scale of these problems. Results are presented of the stationary and nonstationary, axisymmetric and geniunly three-dimensional calculations. Newly developed high-resolution numerical methods are discussed which can be applied to a large variety of astrophysical problems. The bibliography includes 113 references. The review will be published in ``CFD Review 97'' by John Wiley.
R S Steinolfson - One of the best experts on this subject based on the ideXlab platform.
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distances to the termination shock and heliopause from a simulation analysis of the 1992 93 heliospheric radio emission event
Geophysical Research Letters, 1995Co-Authors: R S SteinolfsonAbstract:A new heliospheric radio emission event observed by Voyagers 1 and 2 in mid-1992 is believed to have been produced by the Interaction of an interplanetary shock with the heliopause. The shock is thought to have oriented near the Sun during a period of intense solar activity in late-May and early-June, 1991. The observed travel time of the shock to the heliopause is 408 days; the initial speed is estimated to be between 600 and 800 km/s. We use a numerical gasdynamic simulation of an interplanetary shock, propagating through an equilibrium solution of the solar wind/interstellar Medium Interaction, to compute the distances to the termination shock and the heliopause that are consistent with these observations. For a shock speed of 600 km/s, the termination shock is located at 92 AU, and the heliopause is located at 128 AU. These distances increase to 112 AU and 156 AU when the shock speed is increased to 800 km/s.
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gasdynamic models of the solar wind interstellar Medium Interaction
Geophysical Research Letters, 1994Co-Authors: R S Steinolfson, V J Pizzo, T HolzerAbstract:The Interaction between the solar wind and the interstellar Medium is modeled self-consistently using numerical solutions of the time-dependent gasdynamic equations in spherical and cylindrical coordinates. For the results presented here it is assumed that the solar system moves through the surrounding Medium with a supersonic velocity. After an initial (nonequilibrium) state has been specified, the numerical solution follows the evolution in time until the Interaction relaxes to a dynamic equilibrium. As would be expected, the solutions show the formation of a bow shock upstream of the traveling solar system to deflect the interstellar plasma around the cavity created by the solar wind. A terminiation shock also forms to slow and compress the solar wind plasma. For the simulation in spherical coordinates, the downstream portion of the termination shock reaches equilibrium more than three times further from the Sun than the equilibrium distance to the termination shock on the upstream side.
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an mhd study of the Interaction between the solar wind and the interstellar Medium
Southwest Research Inst. Report, 1993Co-Authors: R S SteinolfsonAbstract:The overall objective of this research program is to obtain a better understanding of the Interaction between the solar wind and the interstellar Medium through the use of numerical solutions of the time-dependent magnetohydrodynamic (MHD) equations. The simulated results will be compared with observations where possible and with the results from previous analytic and numerical studies. The primary progress during the first two years has been to develop codes for 2-D models in both spherical and cylindrical coordinates and to apply them to the solar wind-interstellar Medium Interaction. Computations have been carried out for both a relatively simple gas-dynamic Interaction and a flow-aligned interstellar magnetic field. The results have been shown to compare favorably with models that use more approximations and to modify and extend the previous results as would be expected. Work has also been initiated on the development of a 3-D MHD code in spherical coordinates.
Liangduan Liu - One of the best experts on this subject based on the ideXlab platform.
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a multiple ejecta circumstellar Medium Interaction model and its implications for superluminous supernovae iptf15esb and iptf13dcc
The Astrophysical Journal, 2018Co-Authors: Liangduan Liu, Lingjun Wang, Shanqin Wang, Zigao DaiAbstract:In this paper, we investigate two hydrogen-poor superluminous supernovae (SLSNe), iPTF15esb and iPTF13dcc, whose light curves (LCs) show significant deviation from the smooth rise and fall. The LC of iPTF15esb exhibits two peaks and a post-peak plateau, and furthermore the late-time spectrum of iPTF15esb shows a strong, broad Hα emission line. The early-time LC of iPTF13dcc shows a long-duration bump followed by the second peak. Here, we propose an ejecta-circumstellar Medium Interaction model involving multiple shells/winds and use it to explain the LCs of iPTF15esb and iPTF13dcc. We find that the theoretical LCs reproduced by this model can match observations of iPTF15esb and iPTF13dcc. Based on our results, we infer that the progenitors have undergone multiple violent mass-loss processes before the SN explosion. In addition, we find that the variation trend of our inferred densities of the shells is consistent with that predicted by the stellar mass-loss history before an SN explosion. Further investigations for other bumpy SLSNe/SNe would shed light on their nature and provide a probe for the mass-loss history of their progenitors.
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a multiple ejecta circumstellar Medium Interaction model and its implications for superluminous supernovae iptf15esb and iptf13dcc
arXiv: High Energy Astrophysical Phenomena, 2018Co-Authors: Liangduan Liu, Lingjun Wang, Shanqin Wang, Zigao DaiAbstract:In this paper, we investigate two hydrogen-poor superluminous supernovae (SLSNe) iPTF15esb and iPTF13dcc whose light curves (LCs) show significant deviation from the smooth rise and fall. The LC of iPTF15esb exhibits two peaks and a post-peak plateau, and furthermore the late-time spectrum of iPTF15esb shows a strong, broad H$\alpha$ emission line. The early-time LC of iPTF13dcc shows a long duration bump followed by the second peak. Here we propose an ejecta-circumstellar Medium (CSM) Interaction model involving multiple shells/winds and use it to explain the LCs of iPTF15esb and iPTF13dcc. We find that the theoretical LCs reproduced by this model can well match the observations of iPTF15esb and iPTF13dcc. Based on our results, we infer that the progenitors have undergone multiple violent mass-loss processes before the SN explosion. In addition, we find that the variation trend of our inferred densities of the shells is consistent with that predicted by the stellar mass-loss history before an SN explosion. Further investigations for other bumpy SLSNe/SNe would shed light on their nature and provide a probe for the mass-loss history of their progenitors.
Andrew C. Hiday - One of the best experts on this subject based on the ideXlab platform.
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Mechanisms and Consequences of Dopamine Depletion-Induced Attenuation of the Spinophilin/Neurofilament Medium Interaction.
Neural plasticity, 2017Co-Authors: Andrew C. Hiday, Asma B. Salek, Cameron W. Morris, Michael C. Edler, Morrent Thang, Tyler J. Rentz, Kristie L. Rose, Lisa M. Jones, Anthony J. BaucumAbstract:Signaling changes that occur in the striatum following the loss of dopamine neurons in the Parkinson disease (PD) are poorly understood. While increases in the activity of kinases and decreases in the activity of phosphatases have been observed, the specific consequences of these changes are less well understood. Phosphatases, such as protein phosphatase 1 (PP1), are highly promiscuous and obtain substrate selectivity via targeting proteins. Spinophilin is the major PP1-targeting protein enriched in the postsynaptic density of striatal dendritic spines. Spinophilin association with PP1 is increased concurrent with decreases in PP1 activity in an animal model of PD. Using proteomic-based approaches, we observed dopamine depletion-induced decreases in spinophilin binding to multiple protein classes in the striatum. Specifically, there was a decrease in the association of spinophilin with neurofilament Medium (NF-M) in dopamine-depleted striatum. Using a heterologous cell line, we determined that spinophilin binding to NF-M required overexpression of the catalytic subunit of protein kinase A and was decreased by cyclin-dependent protein kinase 5. Functionally, we demonstrate that spinophilin can decrease NF-M phosphorylation. Our data determine mechanisms that regulate, and putative consequences of, pathological changes in the association of spinophilin with NF-M that are observed in animal models of PD.
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mechanisms and consequences of dopamine depletion induced attenuation of the spinophilin neurofilament Medium Interaction
Neural Plasticity, 2017Co-Authors: Andrew C. Hiday, Asma B. Salek, Anthony J. Baucum, Cameron W. Morris, Michael C. Edler, Morrent Thang, Tyler J. Rentz, Kristie L. Rose, Lisa M. JonesAbstract:Signaling changes that occur in the striatum following the loss of dopamine neurons in the Parkinson disease (PD) are poorly understood. While increases in the activity of kinases and decreases in the activity of phosphatases have been observed, the specific consequences of these changes are less well understood. Phosphatases, such as protein phosphatase 1 (PP1), are highly promiscuous and obtain substrate selectivity via targeting proteins. Spinophilin is the major PP1-targeting protein enriched in the postsynaptic density of striatal dendritic spines. Spinophilin association with PP1 is increased concurrent with decreases in PP1 activity in an animal model of PD. Using proteomic-based approaches, we observed dopamine depletion-induced decreases in spinophilin binding to multiple protein classes in the striatum. Specifically, there was a decrease in the association of spinophilin with neurofilament Medium (NF-M) in dopamine-depleted striatum. Using a heterologous cell line, we determined that spinophilin binding to NF-M required overexpression of the catalytic subunit of protein kinase A and was decreased by cyclin-dependent protein kinase 5. Functionally, we demonstrate that spinophilin can decrease NF-M phosphorylation. Our data determine mechanisms that regulate, and putative consequences of, pathological changes in the association of spinophilin with NF-M that are observed in animal models of PD.