Effects of solar activity in the middle atmosphere dynamical regime over Eastern Siberia, USSR

Lower thermospheric (90 to 120 km) wind data was acquired by ground based spaced-receiver method (HF, LF) near Irkutsk (52 deg N, 104 deg E). There is interrelated solar and meteorological control of lower thermosphere dynamics. Some features of solar control effects on the wind parameters are discussed

The geomagnetic control of the lower thermosphere wind system over East Siberia

The geomagnetic control of ionospheric D region dynamics was revealed and confirmed on the basis of radiophysical wind measurements (1978 to 1983) over East Siberia. The monthly mean parameters of the wind system are different for quiet and disturbed conditions. There is an increase in stability of the meridional wind with increasing level of geomagnetic activity. The influence of geomagnetic storms on the measured wind is considered on the basis of 31 events. There are effects on the phase of the semidiurnal tidal wind, but variations of amplitude are weak. The effect of the geomagnetic storm depends on the intensity and is more clear-cut for the A sub p is greater than 100

Behavior of the emission from atomic oxygen of the atmosphere at 557.7 nm during the events of stratospheric warming over East Siberia

The influence of stratospheric warming on the atomic oxygen emission at 557.7-nm wavelength (airglow) was investigated based on data obtained at the Geophysical Observatory of ISTP SB RAS (52°N, 103°E) in [1997][1998][1999][2000][2001][2002][2003][2004][2005]. In this period, several cases of anomalous behavior of the 557.7-nm emission intensity in the absence of strong geomagnetic disturbances have been recorded. It has been found that these cases of the growth of intensity of atmospheric emission at 557.7 nm in the height region of the mesosphere and lower thermosphere, have been caused by strong stratospheric warming when the disturbance covers a wide range of atmospheric altitudes. It should be emphasized that high concentration of centers of stratospheric warming is characteristic of Asia and, in particular, of the East Siberia that can result in the formation of regional peculiarities in characteristics of the airglow

Functional state of the nigrostriatal system of Krushinsky – Molodkina rats during audiogenic seizure expression

Neurochemical mechanisms of initiation and expression of epileptic seizures are poorly explored, and there are no published data that could demonstrate the functional state of the neuromediator systems at the initial state of seizure in the animals genetically prone to seizure. In the current work, we studied the role of extracellular signal-regulated kinase (ERK1/2) in the regulation of the nigrostriatal glutamate, GABA and dopamine neurons of Krushinsky – Molodkina rats at clonus-tonus and ataxia stages of audiogenic seizure. We demonstrated upregulation of ERK1/2 activity upon audio stimulation which was accompanied by increased activation of Synapsin I in the striatum and substantia nigra in comparison to intact Krushinsky – Molodkina rats. The observed exocytosis activation led to secretion of glutamate in the striatum and, as a result, to stimulation of seizures. However, at clonus-tonus stage in the striatum we revealed the changes that could participate in further inhibition of seizure activity, such as increased phosphorylation of tyrosine hydroxylase upon increased ERK1/2 activity followed by activation of dopamine release in the pars compacta of the substantia nigra. At the same time, enhanced D2 and increased D1 dopamine receptor contents were observed. These data revealed attenuation of direct (pro-seizure) and indirect (anti-seizure) pathways of the regulation of the substantia nigra GABA neurons. We demonstrated activation of GABA in the substantia nigra pars reticulate, which probably results in the inhibition of glutamate neurons of the thalamus and could be one of the mechanisms inhibiting seizure activity during ataxia

The Planetary Wave Activity in Temperatures of the Stratosphere, Mesosphere and in Critical Frequencies of Ionospheric F2 Layer

A large body of experimental evidence lends credit to the existence of a close relationship between ionospheric parameters and the underlying atmosphere. Vertical-incidence ionospheric sounding data and temperature measurements at stratospheric (30 km) and mesospheric (80 km) heights have been used in investigating the interrelation between the occurrence of fluctuations with periods of planetary waves in temperature variations at different heights and in F2 layer critical frequency variations (foF2) under low solar activity conditions for the time interval 2006-2007. The distinctive characteristics of the manifestation of common periodicities of the wave structures under consideration are discussed. The statistically significant periods of stratospheric and mesospheric temperature fluctuations vary from 11 to 49 days, whereas foF2 periodograms show higher-frequency fluctuations with periods of 5, 8, 9, and 10 days. The study revealed a similarity between periodic structures for the variations in the parameters involved

Surface ultraviolet radiation over east Siberia: seasonal variations

The results of spectral measurements of the daily near-noon surface direct solar ultraviolet radiation in the wavelength range of 295–345 nm obtained in Irkutsk (East Siberia) for the time interval of 1998–2000 are presented. For the period under consideration, the seasonal UV radiation variations are analysed that are associated with the total ozone dynamics, the transition of cyclonic and anticyclonic (Siberian anticyclone) periods, the presence of snow cover, and other factors. The analysis reveals an asymmetric behaviour of the seasonal course in ground-level UV radiation around the time of the summer solstice, with seasonal variation dependence on the wavelength. We have determined the irregular variations of surface UV radiation that is typical for the region, with their properties dependent on the season and on the spectral range analysed. The similarity of the above noted features from year to year was revealed.<br><br><b>Key words. </b>Atmospheric composition and structure (Transmission and scattering of radiation; instruments and techniques) – Meteorology and atmospheric dynamics (middle atmosphere dynamics

Postnatal development of the suprachiasmatic nucleus in the rat. Morpho-functional characteristics and time course of tyrosine hydroxylase immunopositive fibers

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