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  • 1
    Electronic Resource
    Electronic Resource
    Absorption of laser light in overdense plasmas by sheath inverse bremsstrahlung (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 3146-3154 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The original sheath inverse bremsstrahlung model [P. J. Catto and R. M. More, Phys. Fluids 20, 704 (1977)] is modified by including the v×B term in the equation of motion, as the evanescent magnetic field in an overdense plasma is greater than the corresponding electric field. It is shown that the present results are significantly different from those derived without the v×B term. The v×B term is also important in interpreting the absorption mechanism. If the v×B term were neglected, the absorption of the light would be incorrectly interpreted as an increase in the transverse components of the canonical momentum, in the case of a normally incident laser light. It is also shown that both the sheath inverse bremsstrahlung and the anomalous skin effect are limiting cases of the same collisionless absorption mechanism. Results from particle-in-cell (PIC) plasma simulations are compared with the absorption coefficient calculated from the linear theory. Finally, the effects of finite density gradients are investigated by PIC simulations. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871146
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanisms for collisionless absorption of light waves obliquely incident on overdense plasmas with steep density gradients (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2702-2709 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For p-polarized laser light obliquely incident on overdense plasmas with steep density gradients, a new collisionless absorption mechanism (sheath-transit absorption) is studied analytically and numerically. Complementary to Brunel's "not-so-resonant'' resonant absorption, and to the conventional resonant absorption, the sheath-transit absorption is most effective for steep density gradients and when the light pressure is less than the plasma pressure. It is also shown that the assumption of instantaneous particle reflection, usually a reasonable assumption for the normal incidence case, is invalid for the p-polarized oblique incident case. A test-particle model which provides a simple physical picture of the sheath-transit absorption is presented. Absorption coefficients obtained from the test-particle model agree reasonably well with those from particle-in-cell (PIC) simulations. The transition from the resonant absorption to the sheath-transit absorption as the density gradient steepens is demonstrated by PIC simulations with a wide range of density gradients. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871527
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  • 3
    Electronic Resource
    Electronic Resource
    Evolution of the Weibel instability in relativistically hot electron–positron plasmas (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3059-3077 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Analytical and numerical studies of the evolution of the Weibel instability in relativistically hot electron–positron plasmas are presented. Appropriate perturbations on the electromagnetic fields and the particle orbits, corresponding to a single unstable mode, are determined analytically and used as initial conditions in the numerical simulations to excite a single unstable mode. A simple estimate of the saturation amplitude is also obtained analytically. Numerical simulations are carried out when a single unstable mode is favorably excited. Comparisons of the simulation results with the analytical ones show very good agreement. Also observed in the simulations are mode competition, mode suppression, and the difference in the long-term evolution between the magnetized and unmagnetized plasmas. For relativistic unmagnetized plasmas, energy-like global constraints, which are conservation laws in addition to the conservation of energy and momentum, are derived. Numerical simulations of the multimode evolution are described. Simulation results show growth in electromagnetic energy in the early stage, a narrowing in the bandwidth and a shift in the peak of the spectrum to longer wavelength in the subsequent evolution, and a decrease in the temperature anisotropy. In a simulation for an unmagnetized plasma, it is observed that the system reaches a steady state halfway through the simulation. In contrast, the peak of the spectrum continues to shift to lower wave number k, and the temperature anisotropy continues to decrease during the entire simulation for a magnetized plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870498
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  • 4
    Electronic Resource
    Electronic Resource
    Macroclump model of the nonlinear evolution of the sideband instability in a helical wiggler free-electron laser (1990)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 3093-3113 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nonlinear evolution of a helical wiggler, free-electron laser is investigated within the framework of a macroclump model for the trapped electrons. The model describes the nonlinear evolution of a right-circularly polarized electromagnetic wave with frequency ωs and wave number ks, and slowly varying amplitude aˆs(z,t) and phase δs(z,t) (eikonal approximation). The model further assumes that the trapped electrons can be treated as tightly bunched macroclumps that interact coherently with the radiation field. The analysis is carried out in the ponderomotive frame, which leads to a substantial simplification in both the analytical and numerical studies. As a first application, the nonlinear evolution of the primary signal is examined when ∂/∂l'=0 (no spatial variation of the wave amplitude and phase). The evolution equations are reduced to quadrature, and the maximum excursion of the wave amplitude aˆs,max is calculated analytically. Subsequently, the nonlinear evolution of the sideband instability is investigated, making use of the equations describing the self-consistent evolution of the wave amplitude aˆs and phase δs, which vary slowly with both space and time, together with the macroclump orbit equation.In the present analysis, the sideband signals are treated as perturbations (not necessarily small) about a constant-amplitude (aˆ0s =const) primary electromagnetic wave with slowly varying phase δ0s(z'). The coupled orbit and field equations are investigated analytically and numerically over a wide range of system parameters to determine detailed scaling properties of the sideband instability. The results of the present analysis suggest that free-electron lasers operating with system parameters corresponding to the strong-pump regime [(Ω'B/Γ0)6/4(very-much-greater-than)1] are least vulnerable to the sideband instability. Moreover, the nonlinear evolution of the sideband instability is investigated numerically for system parameters corresponding to the Los Alamos free-electron laser experiment [Warren et al., IEEE J. Quantum Electron. QE-21, 882 (1985)]. In several aspects, the numerical results are found to be in good qualitative agreement with the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859221
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of the trapped-electron distribution on the sideband instability in a helical wiggler free-electron laser (1990)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 2456-2481 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Use is made of the Vlasov–Maxwell equations to investigate detailed properties of the sideband instability for a helical wiggler free-electron laser with wiggler wavelength λw=2π/k0=const and normalized wiggler amplitude aw=eBˆw/mc2k0=const. The model describes the nonlinear evolution of a right circularly polarized primary electromagnetic wave with frequency ωs, wave number ks, and slowly varying amplitude aˆs(z,t) and phase δs(z,t) (eikonal approximation). The coupled Vlasov and field-evolution equations are analyzed in the ponderomotive frame ("primed'' variables) moving with velocity vp=ωs/(ks+k0) relative to the laboratory. Detailed properties of the sideband instability are investigated for small-amplitude perturbations about a quasi-steady state characterized by an equilibrium electron distribution f0(γ'0) and a primary electromagnetic wave with constant amplitude aˆ0s=const (independent of z' and t') and slowly varying phase δ0s(z'). A formal dispersion relation is derived for perturbations about a general equilibrium distribution f0(γ0) that may include both trapped and untrapped electrons. For the case where only trapped electrons are present, the dispersion relation is reduced to a simple analytical form. Detailed properties of the sideband instability are investigated for the case where the trapped electrons uniformly populate the ponderomotive potential up to an energy γ'M≤γˆ+, where γˆ'+ is the energy at the separatrix. Analysis of the dispersion relation shows that the maximum energy of the trapped-electron population (γM) significantly affects detailed stability properties in the strong-pump and intermediate-pump regimes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859511
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  • 6
    Electronic Resource
    Electronic Resource
    Weibel instability in relativistically hot magnetized electron–positron plasmas (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 3369-3387 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A linear stability analysis is carried out for the Weibel instability in relativistic magnetized electron–positron-pair plasmas, with the propagation direction parallel to the background magnetic field. The instability in the ultrarelativistic regime, with the typical Lorentz factor γ much greater than unity, is emphasized for its relevance to astrophysical sources of synchrotron radiation. Detailed stability properties are examined, in the ultrarelativistic regime, for two model distribution functions, the water-bag distribution function, and a smooth distribution function. The dispersion relations are obtained in closed analytic forms for both distribution functions. The necessary and sufficient conditions for instability are determined when the temperature along the background magnetic field is cold (T(parallel)=0). The dispersion relations are solved numerically with T(parallel)≠0 over a wide range of system parameters to determine the detailed dependence of the instability on the strength of the background magnetic field and the temperature anisotropy. The present analysis shows that both a decrease in temperature anisotropy and an increase in the background magnetic field can cause a significant decrease in growth rate. For the smooth distribution function, it is found that, for a given plasma density, the system stabilizes completely when the background magnetic field is stronger than the moderate threshold value [(ωp±/ωc±)2≤2/π], corresponding to T(parallel)=0. As the temperature anisotropy decreases, the threshold magnetic field decreases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860631
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  • 7
    Electronic Resource
    Electronic Resource
    Purification and characterization of a novel glucooligosaccharide oxidase from Acremonium strictum T1
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular 1118 (1991), S. 41-47 
    Details
    ISSN: 0167-4838
    Keywords: (Acremonian) ; Enzyme characterization ; Enzyme purification ; Fungus ; Glucooligosaccharide oxidase
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0167-4838(91)90439-7
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  • 8
    Electronic Resource
    Electronic Resource
    Purification and characterization of cytochrome o from Azotobacter vinelandii
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Bioenergetics 502 (1978), S. 543-548 
    Details
    ISSN: 0005-2728
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2728(78)90086-5
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  • 9
    Electronic Resource
    Electronic Resource
    Molecular analysis of survival motor neuron (SMN) and neuronal apoptosis inhibitory protein (NAIP) genes of spinal muscular atrophy patients and their parents (1997)
    Springer
    Human genetics 〈Berlin〉 100 (1997), S. 577-581 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have assayed deletions of two candidate genes for spinal muscular atrophy (SMA), the survival motor neuron (SMN) and neuronal apoptosis inhibitory protein (NAIP) genes, in 101 patients from 86 Chinese SMA families. Deletions of exons 7 and 8 of the telomeric SMN gene were detected in 100%, 78.6%, 96.6%, and 16.7%, in type I, II, III, and adult-onset SMA patients, respectively. Deletion of exon 7 only was found in eight type II and one type III patient. One type II patient did not have a deletion of either exon 7 or 8. The prevalence of deletions of exons 5 and 6 of the NAIP gene were 22.5% and 2.4% in type I and II SMA patients, respectively. We also examined four polymorphisms of SMN genes and found that there were only two, SMN-2 and CBCD541-2, in Chinese subjects. In our study, analysis of the ratio of the telomeric to centromeric portion (T/C ratio) of the SMN gene after enzyme digestion was performed to differentiate carriers, normals, and SMA patients. We found the T/C ratio of exon 7 of the SMN gene differed significantly among the three groups, and may be used for carrier analysis. An asymptomatic individual with homozygous deletion of exons 7 and 8 of the SMN gene showed no difference in microsatellite markers in the SMA-related 5q11.2–5q13.3. In conclusion, SMN deletion in clinically presumed child-onset SMA should be considered as confirmation of the diagnosis. However, adult-onset SMA, a heterogeneous disease with phenotypical similarities to child-onset SMA, may be caused by SMN or other gene(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050555
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  • 10
    Electronic Resource
    Electronic Resource
    Lewis (FUT3) genotypes in Taiwanese, Thai, and Filipino populations (2000)
    Springer
    Annals of hematology 79 (2000), S. 599-603 
    Details
    ISSN: 1432-0584
    Keywords: Key words Lewis blood group ; α (1,3/1,4)-Fucosyltransferase (FUT3) ; Taiwanese ; Thai ; Filipino
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The Lewis (Le) blood type comprises two major antigens, Lea and Leb, which are encoded by α (1,2)-fucosyltransferase (FUT2) and α (1,3/1,4)-fucosyltransferase (FUT3). In this study, we analyzed the mutations of FUT3 in Taiwanese, Thai, and Filipino populations and correlated these with serologic phenotypes. One hundred and thirty-seven Taiwanese, 71 Thai, and 125 Filipino were studied unselectively. The frequency of the normal and four other mutant alleles for Taiwanese, Thai, and Filipino, respectively, were as follows: 187/274 (68.2%), 87/142 (61.3%), and 160/250 (64.0%) were wild type (Le); 14/274 (5.1%), 1/142 (0.7%), and 1/250 (0.4%) were a T202C/C314T mutation (le202,314); 35/274 (12.8%), 15/142 (10.6%), and 22/250 (8.8%) had the G508A mutation (le508); and 38/274 (13.9%), 39/142 (27.4%), and 67/250 (26.8%) carried the T1067A mutation (le1067). The le445 and le1007 were not detected in this study. Our result provided the first genetic data of the FUT3 gene in these three populations, and the frequency distribution of mutant alleles among Taiwanese, Thai, and Filipinos demonstrates a significant difference (P〈0.001). In our study, the le202,314 mutation had considerable frequency in the Taiwanese, but the le1067 mutation had a higher frequency in Thai and Filipinos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770000212
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