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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4723-4732 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ wafer curvature measurements were performed to study mechanical stress in amorphous SiO2 during Xe, Ne, and Er ion irradiation at energies in the 0.27–4.0 MeV range. Three phenomena are observed: network compaction, radiation-induced viscous flow, and a nonsaturating anisotropic deformation phenomenon. The radiation-induced viscosity is shown to be inversely proportional to the energy density deposited into atomic displacements. The relation between radiation-induced flow and diffusion is discussed in the context of the Stokes–Einstein relation. Viscous flow serves to relax stress, yet a continuous nonsaturating anisotropic deformation effect causes the stress in the irradiated layer to saturate at nonzero values: Xe irradiation at an energy below 3.6 MeV results in a tensile saturation stress; for higher energies a compressive stress builds up. These effects are explained in terms of competing bulk and surface deformation processes resulting from local heating of the SiO2 around the ion tracks. The macroscopic effect of deformation phenomena is illustrated by showing the surface morphology after 4.9 MeV Er irradiation of silica through a contact implantation mask. Finally, an in situ stress study of an alkali borosilicate glass is presented. In this case a fourth radiation induced effect is observed, namely, the generation and annihilation of volume occupying point defects. These defects are shown to anneal out at room temperature, following a broad spectrum of activation energies. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 140-149 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: A compact expression for the calculation of phase shifts is derived for a potential which is the sum of local and nonlocal parts. Nonlocal potentials can support positive energy bound states, that is, states embedded in the continuous energy spectrum. These states, sometimes referred to as "isolated" states, are not associated with any poles of the S matrix. Some controversy exists in the literature on how such bound states are included in Levinson's theorem; it is found that the phase shift should be taken continuous at the energy of the bound state rather than taken to have a discontinuity of π. For simplicity, the analysis is restricted to the radial s wave Schrödinger equation and separable nonlocal potentials. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2948-2950 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present low energy ion beam mixing as a tool for the fabrication of composite layers with smooth interfaces. Using this tool we make a stack of alternating layers of Si and MoxSiy. We measure composition and interfacial roughness (σ) and find x/y≈5/3 and σ≈4 A(ring). The method can be applied to reduce absorption losses in x-ray multilayer mirrors for high-resolution dispersive purposes, and to increase thermal stability of multilayers. The thickness of the mixed layers is found to be equal to the ion range. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We investigated the effects of stem cell factor (SCF) on histamine release (HR) from human bronchoalveolar lavage (BAL) mast cells. BAL cells were recovered from lavage performed in patients undergoing clinical bronchoscopy. SCF (0.02–20 ng/ml), which is by itself a poor secretagogue (mean ± SEM HR: 3.7 ± 0.9%; n= 27), strongly enhanced HR induced by anti-IgE in a concentration-related manner. Significant potentiation began at 0.2 ng/ml (30 ± 10°0; p〈0.05; n= 12) and reached a plateau at 2 ng/ml (40 ± 10%; P〈0.01 at 2 ng/ml and 45 ± 10%; P〈0.01 at 20 ng/ml; n= 12). In contrast, SCF failed to enhance HR induced by calcium ionophore A23187. Among the BAL cell samples initially unresponsive to anti-IgE (55° of samples), 36% (10/28) were converted to responders if the cells were shortly preincubated with SCF. In 25% of samples (7/27), SCF (20 ng/ml) caused direct HR of 10 ± 2.1 %. The mast cells which released histamine when challenged with SCF also secreted higher levels of histamine in response to anti-IgE and calcium ionophore than those nonresponsive to SCF. While interleukin (IL)-3 and IL-5 (20 ng/ml) were unable to modulate immunologic HR. GM-CSF (20 ng/ml) produced significant potentiation (P〈0.05), which was, however, smaller than that observed with SCF. The rate of responders to anti-IgE in atopic asthma (47 %) was greater than that in control (9%) and intrinsic asthma (10%) but not different from that in some other respiratory diseases such as chronic bronchitis (44%), lung cancer (47%), or interstitial disease (68%,). The potentiation of HR afforded by SCF did not differ significantly among the several disease groups. We conclude that, whatever the underlying respiratory disease, SCF selectively enhances IgE-mediated HR from human BAL mast cells. Furthermore, this cytokine is sometimes necessary to render mast cells able to release histamine in response to anti-IgE.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 182 (1998), S. 687-694 
    ISSN: 1432-1351
    Keywords: Key words Phonotaxis ; Pattern recognition ; Calling song ; Bushcricket Tettigonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The selectivity of female phonotaxis in Tettigonia cantans and T. viridissima was investigated on a Kramer treadmill, with respect to the specific differences in temporal pattern and spectrum of the songs of both species. In choice situations, both species preferred the conspecific song over the heterospecific one. The courses of both species were deflected by about 15–20° from the position of the conspecific song, that of T. viridissima being away from, that of T. cantans in the direction of the heterospecific song. In no-choice situations, song models with the temporal pattern of T. cantans did not attract T. viridissima. Models with the conspecific time pattern but heterospecific spectrum were as attractive as the conspecific model. In contrast, T. cantans was attracted by T. viridissima song presented alone. In choice situations, either spectral or temporal differences were sufficient for discrimination. The preference for the conspecific model gradually disappeared with stepwise reduction of its intensity and was reversed at −12 dB. Acoustic communication alone can serve species isolation in T. viridissima; however, premating isolation in T. cantans must involve other mechanisms. The orientation during the choice situations suggests a serial processing of song recognition and localization for the Tettigonia species.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 180 (1997), S. 621-630 
    ISSN: 1432-1351
    Keywords: Key words Calling song  ;  Phonotaxis  ;  Pattern recognition  ;  Cricket ; Teleogryllus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The phonotactic response of cricket females was investigated on a locomotion compensator to determine the temporal parameters of the male's calling song which are important for species recognition. Two sympatric species (Teleogryllus commodus, T. oceanicus) that show different syllable periods in the chirp and trill parts of their calling songs were used. By their responses T. commodus females exhibited two temporal filters for syllable periods, which were tuned to the species-specific syllable periods occurring during chirp and trill. For song recognition both filters had to be activated and for both a minimum number of three to five consecutive syllable periods was necessary. In contrast, T. oceanicus females showed only one sharply tuned filter corresponding to the chirp part of the male's calling song. This filter was sufficient for calling song recognition. Syllable periods of the trill part also influenced calling song recognition, but these played only a minor role. Carrier frequency was also important for positive phonotaxis. Calling song recognition by T. commodus females is largely based on central nervous processing, while for T. oceanicus both peripheral frequency filtering and central temporal filtering is important.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Der Nervenarzt 68 (1997), S. 309-323 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Creutzfeldt-Jakob Krankheit (CJD) ; Spongiforme Enzephalopathie ; Prion ; Diagnose ; Key words Creutzfeldt-Jakob disease (CJD) ; Spongiform encephalopathy ; Prion ; Diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Since its first description by H.G. Creutzfeldt and A. Jakob, six forms of human spongiform encephalopathies have been described. Besides Creutzfeldt-Jakob disease (CJD), a new variant CJD (nvCJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), fatal familial insomnia (FFI) and potentially familial progressive subcortical gliosis have been reported. The most likely causative agent of these and at least six animal-transmissible spongiform encephalopathies (TSE) is a structurally altered form of a regular cellular protein, designated prion. The best known animal forms are bovine spongiform encephalopathy (BSE) and scrapie. The clinical spectrum of human spongiform encephalopathies has been expanded in recent years by the discovery of new, partially genetically determined forms. The currently available clinical, neurophysiological, neuroradiological, biochemical and molecular-biological methods permit only a probable diagnosis of CJD. A definite diagnosis can only be achieved by the neuropathological demonstration of the pathological prion protein (PrPSc). The transmission of BSE to humans has neither been shown nor definitely excluded.
    Notes: Zusammenfassung Seit der Erstbeschreibung durch Creutzfeldt und Jakob sind bisher 6 humane spongiforme Enzephalopathien, die Creutzfeldt-Jakob-Krankheit (CJD), eine new variant CJD (nvCJD), das Gerstmann-Sträussler-Scheinker-Syndrom (GSS), die fatale familiäre Insomnie (FFI) und möglicherweise die familiäre progressive subkortikale Gliose beschrieben worden. Als wahrscheinlichster Auslöser dieser und von im Tierreich vorkommenden transmissiblen spongiformen Enzephalopathien (TSE), wie der bovinen spongiformen Enzephalopathie (BSE) und von Scrapie, gilt heute ein körpereigenes, im Krankheitsfall in seiner Struktur verändertes Eiweiß, das das Akronym Prion trägt. Das klinische Spektrum menschlicher spongiformer Enzephalopathien hat durch die Beschreibung neuer, teilweise genetisch bedingter Varianten in den letzten Jahren eine deutliche Ausweitung erfahren. Mit den bisher zur Verfügung stehenden klinischen, neurophysiologischen, neuroradiologischen, biochemischen und molekularbiologischen Verfahren läßt sich intra vitam lediglich eine wahrscheinliche Diagnose einer CJD stellen. Eine sichere Diagnose einer humanen spongiformen Enzephalopathie ist nur durch den neuropathologischen Nachweis des pathologischen Prionproteins (PrPSc) möglich. Eine Übertragung der BSE auf den Menschen ist bisher nicht bewiesen, läßt sich gegenwärtig aber auch nicht mit Sicherheit ausschließen.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 1 (1998), S. 39-44 
    ISSN: 1434-601X
    Keywords: PACS:21.10.Re Collective levels and giant resonances – 23.20.Lv Gamma transitions and level energies – 27.90.+b 220 ≤A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Excited bands of 228Th were studied in the 226Ra(α,2n) reaction by gamma-ray and conversion-electron spectroscopy. The first-excited K π=0+ and 2+ bands were identified up to I π= 12+ and 10+, respectively. The spin dependence of the moments of inertia is discussed. The experimental data indicate a structural change of these bands from 228Th to 230Th and 232Th.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-601X
    Keywords: PACS:23.20.-g Electromagnetic transitions – 21.60.Jz Hartree-Fock and random-physe approximations – 27.90.+b 220 ≤ A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The electron-capture decay of 228Pa to levels in 228Th was studied using mass-separated sources and a γ-ray detection system consisting of five Compton-suppressed Ge detectors. A total of 87 levels were observed up to an excitation energy of 2 MeV which are connected by approximately 500 γ-ray transitions. The complete octupole quadruplet, three excited K π=0+ bands and two K π=2+ bands were identified below 1.4 MeV. The observed level structure is compared to calculations within the quasiparticle-phonon nuclear model. The surprisingly good agreement indicates that 228Th has less transitional character than hitherto assumed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 3 (1998), S. 263-270 
    ISSN: 1434-601X
    Keywords: PACS: 23.20.-g Electromagnetic transitions – 23.20.Nx Internal conversion – 25.70.Gh Compound nucleus – 27.90.+b 220 ≤ A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The nuclear structure of 227Th was studied in the 226Ra (α,3n) reaction by gamma-ray and conversion-electron spectroscopy. Six rotational bands were identified with spins upto approximately 39/2. Attempts to connect these bands to the low-lying levels known from radioactive-decay work were not fully successful.
    Type of Medium: Electronic Resource
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