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  • 1
    Electronic Resource
    Electronic Resource
    Macro-particle simulations of collisionless magnetic reconnection (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2920-2930 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The basic process of collisionless reconnection is studied in terms of coalescence of two flux bundles using an implicit particle simulation of two-dimensions. As the toroidal electric field is generated by magnetic induction, an elongated current sheet whose width is a few electron skin depths is formed. Sub-Alfvénic plasma outflow off the reconnection region is generated in the poloidal plane which spreads within the dual fans originating at the X-point. Significant toroidal acceleration and streaming of the electrons without direct thermalization is observed in the current sheet. The electron parallel transport is proved to enhance the reconnection rate by comparing the implicit and hybrid-particle simulations; in the latter the electrons are spatially frozen to the ions. The reconnection rate is insensitive to finite Larmor radii of the ions in the regime where the magnetic flux merges constantly in time. The simulation results support that the collisionless reconnection is mediated by the electron inertia. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871192
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  • 2
    Electronic Resource
    Electronic Resource
    Asymmetry and thermal effects due to parallel motion of electrons in collisionless magnetic reconnection (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 4010-4017 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fast collisionless reconnection of magnetic flux loops by the macro-particle simulation code shows significant asymmetry of the plasma flow under an ambient toroidal magnetic field. The parallel motion of electrons induced by the reconnection electric field is found to produce large density and toroidal magnetic field inhomogeneities of a quadrupole shape, δn/n0∼0.3, unlike the m=1 mode. The divergence of the plasma flow is locally not identical to zero with each species, ∇⋅V(s)≠0 (s=e,i), due to the electron spatial movement along the magnetic field. This internal structure results in a thick current layer and enhances the reconnection process. A plasmoid that impedes magnetic reconnection is created when the parallel mass diffusivity of electrons arising from their thermal motion is suppressed (the fluid limit). The reconnection rate becomes a smoothly increasing function of the ion mass and an inverse of the toroidal magnetic field, the latter of which being due to the compressional effect. The rate is drastically reduced when the ion Larmor radius far exceeds the ion skin depth. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871573
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  • 3
    Electronic Resource
    Electronic Resource
    Excitation of kinetic Alfvén waves by resonant mode conversion and longitudinal heating of magnetized plasmas (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 325-332 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Simulation of the kinetic Alfvén wave is performed using a two-and-one-half-dimensional (2 (1)/(2) -D) macroscale particle [magnetohydrodynamic (MHD) scale kinetic] simulation code. An oscillating antenna current is applied in one of the boundary regions to launch MHD perturbations into an inhomogeneous plasma in which a sheared magnetic field is present. It is shown that the applied perturbation is mode converted into the kinetic Alfvén wave at the Alfvén resonance layers, resulting in resonant heating of both the ions and electrons. When the plasma beta is relatively low, only the electrons are heated along the ambient magnetic field. The electron heating rate is found to be scaled as dTe(parallel)/dt∝β1/2e 〈δB2y〉, where βe is the electron beta and 〈δB2y〉 is the wave magnetic field intensity. In contrast, ion heating occurs when the ion beta is close to unity and the temperature ratio satisfies Te/Ti〉1. Besides plasma heating, it is found that the plasma particles are accelerated along the ambient magnetic field in the direction of the wave propagation through Landau resonance with the kinetic Alfvén wave.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859145
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  • 4
    Electronic Resource
    Electronic Resource
    Macroscale particle simulation of relativistic electron beam injection into a magnetized plasma channel (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 3823-3831 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A large-scale particle simulation of an intense relativistic electron beam injection into a longitudinally periodic and magnetized, three-dimensional plasma channel is performed with application to the steady-state current drive of tokamaks. It is found that the electromagnetically beam-induced electric field uniformly decelerates the beam electrons and generates a plasma return current as far as the injection continues. The beam electrons are decelerated also by the scaler potential field especially before the beam path becomes closed. A net longitudinal current, and hence the azimuthal magnetic field, is formed in the vicinity of the beam path after the return current has reached a steady force–balance equilibrium with the electric field and anomalous friction. The net saturation current is independent of the injection beam current and is scaled as Inet∼(γ2−1)1/2, where γ=(1−v2b/c2)−1/2 and vb is the velocity of the electron beam. For γ(very-much-greater-than)1, a macroscale helical instability develops and prevents the net current from reaching the level given by the aforementioned scaling. This instability is suppressed by application of a strong longitudinal magnetic field, which recovers the net current of the previous scaling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865765
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular dynamics of strongly coupled multichain Coulomb polymers in pure and salt-added Langevin fluids (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 8176-8188 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The multichain effect and also the effect of added salt on randomly copolymerized charged polymers (polyampholytes) in a Langevin fluid are studied with the use of molecular dynamics simulations. The monomers of opposite signs tend to form loose complexes, which makes the Coulomb force attractive on average. With multichain polyampholytes, the typical state at high temperature is a container-bound one-phase state of separated chains with a substantial void among them. The association and dissociation processes occur repeatedly, with the former process a few times faster than the latter. A glass transition occurs when temperature is lowered. A compact and glassy globule in a segregated phase, which resembles that of a single-chain polyampholyte, is a typical state at low temperature due to the Coulomb force. The probability of losing this state is as low as Pdis∼exp(−N3/2), with N the number of monomers. The critical temperature defined by overlapping of the chains increases with molecular weight and stiffness of the chains, and is less sensitive to the number of the chains. An alternate charge sequence makes a difference only when its block size is quite small. The addition of salt suppresses the formation of a dense globule by shielding the electric field; however, this is not effective when the salt ions are not allowed to penetrate well into the globule. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478719
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  • 6
    Electronic Resource
    Electronic Resource
    Giant charge inversion of a macroion due to multivalent counterions and monovalent coions: Molecular dynamics study (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 567-574 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report molecular dynamics simulation of the (overall neutral) system consisting of an immobile macroion surrounded by the electrolyte of multivalent counterions and monovalent coions. In a short time (〈 a few nanoseconds), counterions adsorb on the macroion surface in the amount much exceeding neutralization requirement, thus effectively inverting the sign of the macroion charge. We find two conditions necessary for charge inversion, namely, counterions must be multivalently charged and Coulomb interactions must be strong enough compared to thermal energy. On the other hand, coion condensation on the multivalent counterions similar to Bjerrum pairing is the major factor restricting the amount of charge inversion. Depending on parameters, we observe inverted charge up to about 200% the original charge of the macroion in absolute value. The inverted charge scales as ∼ζ1/2 when ζ〈1 and crosses over to ∼ζ for ζ〉1, where ζ=(A0/rs)2, rs is the Debye screening length in the electrolyte and A0 is the distance between adsorbed counterions under neutralizing conditions. These findings are consistent with the theory of "giant charge inversion" [Phys. Rev. Lett. 85, 1568 (2000)]. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1377033
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  • 7
    Electronic Resource
    Electronic Resource
    Clinical study of IgA antibody against hepatitis C virus core antigen in patients with type C chronic liver disease (1995)
    Springer
    Digestive diseases and sciences 40 (1995), S. 457-464 
    Details
    ISSN: 1573-2568
    Keywords: IgA class antibody ; type C chronic liver disease ; HCV core ; histological activity ; IFN therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Immunoglobulin A class antibody to hepatitis C virus core antigen (IgA anti-HCc) was measured in the serum of 128 patients with type C chronic liver disease. Fifty-eight patients (45.3%) were seropositive. IgA anti-HCc was detected in only one of 20 patients with chronic persistent hepatitis; however, 52.3% (46/88) of patients with chronic active hepatitis and 55% (11/20) of patients with liver cirrhosis were seropositive. Histological examination revealed that 22 (71.0%) of 31 patients with severe disease activity were seropositive compared to 35 (44.9%) of 78 patients with moderate (P〈0.05) and one (5.3%) of 19 patients with mild (P〈0.01) histological changes. IgA anti-HCc was measured sequentially in 65 patients who underwent interferon therapy. There was a significant difference between responders and other patients in the mean ratio of IgA anti-HCc titers one month after therapy. Three months after therapy, IgA anti-HCc was detectable in only two of 15 responders who were IgA anti-HCc seropositive at the start of therapy. In contrast, IgA anti-HCc reappeared three months after therapy despite a temporary decrease to undetectable levels in all nonresponders. We conclude that IgA anti-HCc is a useful marker to identify the presence of active type C liver disease and that the disappearance of IgA anti-HCc three months after interferon therapy predicts a good response in treated patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02065435
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  • 8
    Electronic Resource
    Electronic Resource
    IgM and IgA antibodies generated against hepatitis C virus core antigen in patients with acute and chronic HCV infection (1994)
    Springer
    Digestive diseases and sciences 39 (1994), S. 2022-2031 
    Details
    ISSN: 1573-2568
    Keywords: hepatitis C virus ; IgA ; IgM ; IgG ; HCV RNA ; high performance liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Antibody subclasses directed against the core protein (HCc) of hepatitis C virus (HCV) were measured in 27 patients with acute non-A, non-B (NANB) hepatitis, and 99 patients with chronic HCV-associated liver disease. IgM, IgA, and IgG anti-HCc responses were observed in 11 (40.7%), 7 (25.9%), and 18 (67%) patients with acute NANB hepatitis, respectively. Twenty-four (24.2%) and 40 (40.4%) patients with chronic HCV infection also had detectable IgM and IgA, respectively. IgM anti-HCc inconsistently detected acute infection, and HCV ribonucleic acid (RNA) could be detected preceding the rise in anti-HCc antibodies in five consecutive patients with acute hepatitis. IgM anti-HCc also could not distinguish acute from chronic infection and did not correlate with histologic progression. However, the form of IgA present (polymeric vs monomeric) did discriminate acute from chronic infection and the IgA anti-HCc titer correlated with histologic evidence of liver disease in patients with chronic HCV infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02088141
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  • 9
    Electronic Resource
    Electronic Resource
    Clinical evaluation of three anti-HCV ELISAs in patients with various liver diseases (1992)
    Springer
    Digestive diseases and sciences 37 (1992), S. 1268-1274 
    Details
    ISSN: 1573-2568
    Keywords: ELISA systems ; HCV antibody ; HCV-RNA ; liver disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We measured antibodies to hepatitis C virus (HCV) in 380 patients with various liver diseases by three enzyme-linked immunosorbent assays (ELISAs): HCV antibody ELISA test (C100), KCL-163 (KCL) corresponding to the nonstructural protein of HCV, and JCC based on the translation product of the presumptive HCV core gene. Of 233 cases of non-A, non-B (NANB) liver disease, 63.9% were anti-C100 positive, 69.1% were anti-KCL positive, and 79.8% were anti-JCC positive. Detection of serum HCV-RNA in 213 cases of chronic NANB liver disease revealed that the concordance was 80.3% for C100, 86.4% for KCL, 94.8% for JCC, and 95.3% for all three ELISAs. Overall, 85.4% of chronic NANB cases were considered to have type C disease with HCV infection. The most reliable assays for diagnosing chronic NANB liver disease as type C appeared to be the KCL and JCC ELISAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01296571
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  • 10
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    Wii Fit U intensity and enjoyment in adults (2014)
    BioMed Central
    Details
    Publication Date: 2014-08-27
    Description: Background: The Wii Fit series (Nintendo Inc., Japan) provides active video games (AVGs) to help adults to maintain a sufficient level of daily physical activity (PA). The second generation of home AVG consoles is now emerging with new game modalities (including a portable mini screen in the case of the new Wii U). The present study was performed to investigate the intensity and enjoyment of Wii Fit U games among adults.FindingsMetabolic equivalent (METs, i.e., intensity) of the Wii Fit U activities were evaluated using metabolic chambers in 16 sedentary adults (8 women and 8 men). A short version of the physical activity enjoyment scale was completed for each activity. Wii Fit U activities were distributed over a range from 2.2 +/- 0.4 METs (Hula dance) to 4.7 +/- 1.2 (Hip-hop dance). Seven activities were classified as light-intensity PA (
    Electronic ISSN: 1756-0500
    Topics: Biology , Medicine
    Published by BioMed Central
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