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  • 1
    Electronic Resource
    Electronic Resource
    Monte Carlo and spin dynamics study of the anisotropic Heisenberg model in two dimensions : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5746-5748 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By using Monte Carlo and molecular dynamics we study the static as well as the dynamical behavior of the classical two dimensional anisotropic Heisenberg model. Our results show that the vortices developed in such a model exhibit two different behaviors depending if the value of the anisotropy λ lies below or above a critical value λc. The in-plane and out-of-plane correlation functions were obtained numerically for λ〈λc and λ〉λc. We found that the out-of-plane dynamical correlation function exhibits a central peak for λ〉λc but not for λ〈λc at temperatures above TKT. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364712
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  • 2
    Electronic Resource
    Electronic Resource
    Chemoluminescence generation and MTT dye reduction by polymorphonuclear leukocytes from periodontal disease patients (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 29 (1994), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Alterations of polymorphonuclear leukocytes (PMNs) functions have been reported in patients with severe forms of some periodontal disease. In this study we evaluated the chemoluminescence generation and MTT dye reduction by human PMN in patients with juvenile periodontitis (JP), rapidly progressive periodontitis (RPP) and adult periodontitis (AP) during protein kinase C (PKC) activation or during the phagocytosis of opsonized zymosan. The results demonstrated that only PMNs of JP patients showed a decreased chemoluminescence generation and MTT dye reduction during the phagocytosis of opsonized zymosan (p 〈 0.05). The time to reach the maximal peak during the PKC activation on the chemoluminescence reaction was evaluated and JP PMNs patients demonstrated a depressed value (7.0 ± 0.4 min) compared with healthy volunteers (13.8 ± 0.5 min). The etiology and importance of such cellular alterations in the immunopathogenesis of the periodontal disease are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1994.tb01098.x
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  • 3
    Electronic Resource
    Electronic Resource
    An eruptive prominence and associated cm-mm emission outside the solar limb (1988)
    Springer
    Solar physics 116 (1988), S. 83-89 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present radio maps at 22 and 44 GHz which show the emission before and after the eruption of a quiescent prominence located at the west limb. The observed radiation following the eruption is not consistent with thermal bremsstrahlung mechanism. It can be interpreted as due to gyrosynchrotron emission of nonthermal electrons. Our observations appear to be similar to the microwave radiation observed in post-flare loops; this radiation is due to nonthermal electrons trapped in the closed magnetic structures formed after the prominence eruption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171716
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  • 4
    Electronic Resource
    Electronic Resource
    A multibeam antenna for solar MM-wave burst observations with high spatial and temporal resolution (1992)
    Springer
    Solar physics 142 (1992), S. 157-170 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper a new method for the determination of the position of microwave burst sources on the Sun, its implementation and first observational results, are presented. The 13.7 m antenna at Itapetinga with a five-channel receiver operating at 48 GHz and with a time resolution of 1 ms is used. Five horn antennas clustered around the focus of the Cassegrain reflector provide 5 beams diverging by about 2′. This configuration allows the observation of different parts of an active region and the determination of the center of the burst position with an accuracy of 5″ to 20″ depending on the angular distance relative to the antenna axis. The field of view is ≈ 2′ by ≈ 4′. The time resolution of 1 ms is suitable to search for fast structures at 48 GHz. A total bandwidth of 400 MHz is used in order to achieve a sensitivity of 0.04 s.f.u. sufficient for the detection of weak bursts. First observational results of the flare on May 11, 1991 show a well-located source position during all stages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156639
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  • 5
    Electronic Resource
    Electronic Resource
    Time delays in solar bursts measured in the mm-cm range of wavelengths (1982)
    Springer
    Solar physics 81 (1982), S. 159-172 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Various solar bursts have been analysed with high sensitivity (0.03 sfu, rms) and high-time resolution (1 ms) at two frequencies in the millimeter wave range (22 GHz and 44 GHz), and with moderate time resolution (100 ms) by a patrol telescope at a frequency in the microwave range (7 GHz). It was found that, in most cases, burst maximum emission is not coincident in time at those frequencies. Preceding maximum emission can be either at the higher or at the lower frequency. Time delays ranged from about 3 s to near coincidence, defined within 10 ms. Some complex bursts presented all kinds of delays among different time structures, and sometimes nearly uncorrelated time structures. Large time delays favour the association of the dynamic effects to shock wave speeds. Directional particle acceleration in complex magnetic configuration could be considered to explain the variety of the dynamic effects. Fastest burst rise times observed, less than 50 ms at 44 GHz and at 22 GHz, might be associated to limiting formation times of emission sources combined with various absorption mechanisms at the source and surrounding plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151987
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  • 6
    Electronic Resource
    Electronic Resource
    Spatial positions of fast-time structures of a solar burst observed at 48 GHz (1995)
    Springer
    Solar physics 159 (1995), S. 143-155 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The impulsive solar burst of October 28, 1992 showed temporal and spatial fine structures that were observed at 48 GHz with the multi-beam antenna of the Itapetinga Radio Observatory. The relative positions of burst centroids were determined with a spatial accuracy of 2″, with a temporal resolution of 1 millisecond. The burst intensity time profile shows fast pulses of about one second duration, superimposed by subsecond time structures. The spatial analysis of the fast pulses suggests that the emission originated from distinct locations, separated by about 5″. Our results favour the idea that impulsive solar bursts are a superposition of small elementary events spread both in time and space, probably resulting from discontinuous energy release processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00733038
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  • 7
    Electronic Resource
    Electronic Resource
    A method for arc-second determination of solar burst emission centers with high time resolution and sensitivity at 48 GHz (1995)
    Springer
    Solar physics 159 (1995), S. 157-171 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A 48 GHz five-radiometer front end was installed at the Cassegrain focus of the 13.7-m Itapetinga antenna for the observation of solar bursts. The system works with five beam patterns partly overlapping. The five antenna temperatures are recorded with a temporal resolution of 1 millisecond, including time and antenna position. The ratios of the incoming antenna signals are used to determine the centroid of burst emission. Its coordinates are determined from groups of three receivers by using a least-square fit. In favourable observing conditions we obtain an angular accuracy of about 2 arc sec (r.m.s.), with a time resolution of 1 ms and a sensitivity of 0.05 s.f.u. The accuracy of the antenna tracking, the absolute pointing and the quality of radio seeing at Itapetinga are discussed. A preliminary analysis of an impulsive solar burst event is used to illustrate the capabilities of the method described here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00733039
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  • 8
    Electronic Resource
    Electronic Resource
    The simplest solar microbursts flux and circular polarization at 22 GHz (1985)
    Springer
    Solar physics 95 (1985), S. 155-165 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The simplest solar microwave microbursts detected with high sensitivity may be the response to the simpler energetic burst injections. Seventeen events from this category were identified in a series of more than 150 bursts recorded in 21–26 November, 1982. This first systematic study suggest that microbursts e-folding rise times concentrate into two classes of time scales, 0.05 s 〈 t ≪ 1 s and 0.5 s ⪝ t ⪝ 2 s. Microbursts’ circular polarization present a dominant steady or slowly varying component that sets in before maximum emission. In some cases a faster component of polarization was found superimposed, which is not always well correlated in time with flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162643
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  • 9
    Electronic Resource
    Electronic Resource
    Solar burst with millimetre-wave emission at high frequency only (1985)
    [s.l.] : Nature Publishing Group
    Nature 313 (1985), S. 380-382 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Past observations at centimetre-millimetre wavelengths indicate that certain bursts can display turnover frequencies which are higher than 30 GHz (l 〈 10 mm)4-9. One very large burst exhibited a spectral 'flattening' in the range 30-71 GHz (refs 4, 5), which was also found for a few other ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/313380a0
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  • 10
    Electronic Resource
    Electronic Resource
    Sub-second pulsations simultaneously observed at microwaves and hard X rays in a solar burst (1983)
    [s.l.] : Nature Publishing Group
    Nature 302 (1983), S. 317-319 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A solar sub-flare occurred on 4 November 1981 at 18 h 28 min 20 s UT. The associated radio and X-ray bursts, shown in compressed time scale in Fig. la, b, reveal that the correlation of the major burst time structures is poor among the three microwave frequencies, and between microwaves and hard X ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/302317a0
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