The time profiles of the solar microwave emission exhibit various phenomona reflecting the evolution of magnetic flux tubes before and during the onset of flare events. Different scenarios are posslble to describe the processes of energy release in a flux tube and the interaction of a number of tubes during the preflare stage and the early flare development, Multi-peak structures at quite
different time scales displayed by flux records at mm-, cm-, and dm-waves are examined; they rise the question how to distinguish between repeated energy release at one site and the propagation of the flare disturbances over an extended source area, A discussion of observed time scales and released energy in the frame of some scenarios is carried out.
The protective effect of therapeutic hypothermia in cardiac arrest survivors (CAS) has been previously well documented. Animal studies have indicated that attenuation of tissue oxidative stress (OS) may be involved in the mechanisms that lead to the beneficial effect of hypothermia. The extent of OS and nitric oxide (NO) production in adult CAS treated with endovascular hypothermia is, however, unknown. A total of 11 adult patients who experienced cardiac arrest out of hospital were included in the present study, and all were treated with mild hypothermia using the Thermogard XP (Alsius, USA) endovascular system. A target core temperature of 33 °C was maintained for 24 hours, with a subsequent rewarming rate of 0.15 °C per hour, followed by normothermia at 36.8 °C. Blood samples for the measurement of nitrotyrosine and nitrate/nitrite levels were drawn at admission and every 6 hours thereafter for two days. During the hypothermic period, the levels of nitrotyrosine and nitrates/nitrites were comparable with baseline values. During the rewarming period, serum levels of both parameters gradually increased and, during the normothermic period, the levels were significantly higher compared with hypothermic levels (nitrotyrosine, P<0.001; nitrates/nitrites, P<0.05). In our study, significantly lower levels of nitrotyrosine and nitrates/nitrites were demonstrated during hypothermia compared with levels during the normothermic period in adult CAS. These data suggest that attenuation of OS and NO production may be involved in the protective effect of hypothermia in adult CAS., A. Krüger ... [et al.]., and Obsahuje seznam literatury
This paper reports on some consequences of a comparison between model calculations of the S-component solar radio emission and observations of active regions at different wavelengths in the microwave range. Calculations of the transfer of the Scomponent emission were carried out on the base of horizontally averaged semi-empiricalv models of the solar atmosphere above sunspots and plage regions consistent with optical and EUV observations and account for Coulomb bremsstrahlung and gyromagnetic emission in dipole-like or
force-free extrapolated magnetic field configurations,
While the mean characteristics are quite in accordance, discrepancies between observations and calculation arise mainly with respect to fine structures, Considering such discrepancies, (i) possible reasons for an obvious lack of observed ring structures of S-component sources above sunspots are discussed. (ii) Subtelescopic fine structures in plage regions are predicted whereas bright plage elemente are assuraed to be embedded in a quasi-quiet background. (iii) Different kinds of loop emissions are considered, among them strange cases of persistent "hot" loop emission connected with emerging magnetic flux regions.
Based on observations of the extraordinary behind-limb flare on February 16, 1984 the radio-flux time profiles at different
dm-wavelengths and dynamic spectrum corresponding
to a source height z > 200000 km above the photosphere are
compared with hard X-ray observations reported by Kane et al.
(1987). The nature of the dm-emission and implications on the
flare process are discussed. Dependíng on the emission
process estimations of relevant plasma parameters (electron
density, magnetic field) are given.
Part I of this review considers the outcome of different methods of observation of active regions at mm- and cm-v/aves exploring the source structures and parameters in the chromosphere and corona. Calculations of emission models invoking bremsstrahlung and gyromagnetic radiation are summarlzed applying for a great
variety of physical conditions. Diagnostic capacities of different kinds of microwave burst emission are briefly taken into account.
Part II of the review considers the dm- and m-radio spectral observations as diagnostic tool for the determination of plasma parameters in the coronal parts of solar active regions. The main attention is devoted to the radio diagnoetics of solar flares. The most important types of dm- and m-radio bursts are presented.
the latest theoretical and observational results summarized and their diagnostic aapects briefly discussed.