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This paper begins with a review of the well-known KdV hierarchy, the $N$-th Novikov equation, and its finite hierarchy in the classical commutative case. This finite hierarchy consists of $N$ compatible integrable polynomial dynamical systems in $\mathbb{C}^{2N}$. We discuss a non-commutative version of the $N$-th Novikov hierarchy defined on the finitely generated free associative algebra ${\mathfrak{B}}_N$ with $2N$ generators. Using the method of quantisation ideals in ${\mathfrak{B}}_N$, for $N=1,2,3,4$, we obtain two-sided homogeneous ideals ${\mathfrak{Q}}_N\subset{\mathfrak{B}}_N$ (quantisation ideals) that are invariant with respect to the $N$-th Novikov equation and such that the quotient algebra ${\mathfrak{C}}_N = {\mathfrak{B}}_N/ {\mathfrak{Q}}_N$ has a well-defined Poincare-Birkhoff-Witt basis. This allows us to define the quantum $N$-th Novikov equation and its hierarchy on ${\mathfrak{C}}_N$. We derive $N$ commuting quantum first integrals (Hamiltonians) and represent the equations of the hierarchy in the Heisenberg form. Essential for our research is the concept of cyclic Frobenius algebras, which we introduced in our recent paper. In terms of the quadratic form that defines the structure of a cyclic Frobenius algebra, we explicitly express the first integrals of the $N$-th Novikov hierarchy in the commutative, free, and quantum cases.

Background. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective treatment method of refractory and recurrent forms of acute leukemia in children, while the question of choosing a conditioning regimen in order to achieve the best treatment results remains debatable. Conditioning based on total body irradiation (TbI) was confirmed to be most effective in some trials, but there are still issues of overcoming early and late toxicity, as well as difficulties in planning and routing patients.Aim. To share the experience of interdisciplinary patient management during the conditioning period with TbI inclusion in Saint petersburg, to evaluate the feasibility, toxicity and effectiveness of the method.Materials and methods. patients undergoing allo-HSCT for high risk acute lymphoblastic leukemia conditioned either with TbI (n = 12) or chemotherapy (n = 10) were included. Medical data were retrospectively analyzed with an assessment of the following transplant outcomes: HSCT-associated toxicity, the frequency and severity of infectious complications, graft versus host disease, as well as overall and event-free survival rates. we have evaluated radiotherapy plans in order to assess the compliance of radiation exposure with acceptable values for critical organs.Results. All patients with acute lymphoblastic leukemia in both groups received appropriate myeloablative conditioning. According to the study results, despite the lack of significance, we obtained differences in HSCT-associated mortality (8.3 and 30 %; p = 0.151), 2-years overall and event-free survival (66 ± 13.6 and 36 ± 16.1 %; p = 0.122) in group with TbI and HdCT respectively. It should be noted that there was a trend towards a decrease of toxic reactions frequency in case of TbI-containing regimens; however we didn’t reveal any significant differences in the number of infectious complications during post-transplant period. The median follow-up was 24.2 months and there were no signs of delayed toxicity.Conclusion. TbI-based conditioning was well tolerated with a low incidence of early and delayed toxicity, better overall and event-free survival. based on feasibility of TbI in Saint petersburg hospitals it is possible to recommend the method in routine practice, taking into account clinical indications.

We described a case report of transcatheter aortic valve replacement in conditions when the aortic stenosis anatomy does not make it possible to perform retrograde left ventricular catheterization, and the patient’s condition severity does not allow performing transapical or surgical aortic valve replacement. The presented technique of interatrial septal puncture with antegrade passage of the guidewire through the mitral and aortic valves and the venoarterial looping demonstrates an elegant way to solve this clinical situation, and can be adopted by specialists performing transcatheter interventions in severe aortic stenosis.

Timely diagnostics and treatment of cytomegalovirus infection in pregnant women and newborns allow to avoid serious consequences, preserving the life and health of the child. The article provides an example of antenatal diagnosis of congenital cytomegalovirus infection in the fetus (positive result of polymerase chain reaction in umbilical cord blood), treatment with umbilical transfusion of donor red blood cells, postnatal therapy with antiviral drugs, including ganciclovir and specific immunoglobulin. The issues of assessing the risk of congenital cytomegalovirus infection, approaches to its prevention and treatment during pregnancy are discussed.

This article presents some results and reflections of the current study of the intangible cultural heritage of St. Petersburg, including the definition of the intangible characteristics of the UNESCO World Heritage Site “The Historical Center of St. Petersburg and related group of monuments” (hereinafter — World Heritage Site).The concept of the “intangible heritage” is defined and its role in the formation of the city’s identity of St. Petersburg youth is indicated. Practices and values of the regional identity of the young generation are revealed.The work used sociological both quantitative and qualitative methods: Internet survey, analysis of documents, interviews and examinations of young people’ self-perception, self-identity and their awareness of the city. The answers were analyzed by the authors from the standpoints of the individual habits of the city’s residents, as well as professionals from related fields of knowledge (architecture, cultural studies, philology, psychology, sociology, jurisprudence) involved in urban projects to popularize the city’s cultural heritage.

We discuss the concept of Lax-Darboux scheme and illustrate it on well known examples associated with the Nonlinear Schro¨dinger (NLS) equation. We explore the Darboux links of the NLS hierarchy with the hierarchy of Heisenberg model, principal chiral field model as well as with differential-difference integrable systems (including the Toda lattice and differential-difference Heisenberg chain) and integrable partial difference systems. We show that there exists a transformation which formally diagonalises all elements of the Lax-Darboux scheme simultaneously. It provides us with generating functions of local conservation laws for all integrable systems obtained. We discuss the relations between conservation laws for systems belonging to the Lax-Darboux scheme.

The modified final-state interaction theory taking into consideration the Coulomb interaction between two-fragment nuclear resonance decay products and accompanying reaction products is developed including the case of near-threshold resonances. The branching ratio change is also studied for the near-threshold resonance 7Li*(Ex = 7.45 MeV), which is formed in the reaction 7Li(α, α)7Li* at Eα = 27.2 MeV.

Crustal earthquakes with magnitude 6.0>M≥5.5 observed in Italy for the period 1979–2009 including the last one at L'Aquila on 6 April 2009 were considered to check if the earlier obtained relationships for ionospheric precursors for strong Japanese earthquakes are valid for the Italian moderate earthquakes. The ionospheric precursors are based on the observed variations of the sporadic E-layer parameters (h'Es, fbEs) and foF2 at the ionospheric station Rome. Empirical dependencies for the seismo-ionospheric disturbances relating the earthquake magnitude and the epicenter distance are obtained and they have been shown to be similar to those obtained earlier for Japanese earthquakes. The dependences indicate the process of spreading the disturbance from the epicenter towards periphery during the earthquake preparation process. Large lead times for the precursor occurrence (up to 34 days for M=5.8–5.9) tells about a prolong preparation period. A possibility of using the obtained relationships for the earthquakes prediction is discussed.

A critical analysis of recent publications devoted to the NmF2 pre-storm enhancements is performed. There are no convincing arguments that the observed cases of NmF2 enhancements at middle and sub-auroral latitudes bear a relation to the following magnetic storms. In all cases considered the NmF2 pre-storm enhancements were due to previous geomagnetic storms, moderate auroral activity or they presented the class of positive quiet time events (Q-disturbances). Therefore, it is possible to conclude that there is no such an effect as the pre-storm NmF2 enhancement as a phenomenon inalienably related to the following magnetic storm. The observed nighttime NmF2 enhancements at sub-auroral latitudes may result from plasma transfer from the plasma ring area by meridional thermospheric wind. Enhanced plasmaspheric fluxes into the nighttime F2-region resulted from westward substorm-associated electric fields is another possible source of nighttime NmF2 enhancements. Daytime positive Q-disturbances occurring under very low geomagnetic activity level may be related to the dayside cusp activity.

Earlier revealed seasonal/latitudinal variations of the occurrence for positive and negative F2-layer Q-disturbances have been interpreted in the framework of the present-day concept of the thermosphere-ionosphere interaction. The basic process is the solar-driven and storm-induced thermospheric circulation's interaction which varies with season and latitude. Such morphological features as clustering of negative Q-disturbances around winter solstice and the appearance of an additional occurrence of summer peak at lower latitudes, the equinoctial occurrence peaks for positive Q-disturbances and their merging to one summer peak at lower latitudes can be explained in the framework of this concept. Moreover, seasonal/latitudinal variations of the occurrence for usual storm-induced F2-layer disturbances, which exhibit quite different morphology, are also explained within this concept and this may be considered as its success. Although some types of F2-layer Q-disturbances are obviously related to the impact from below, the analyzed seasonal/latitudinal occurrence variations are shown to have their origin in the thermosphere itself.

A previous approach to the ionospheric long-term trend analysis has been applied to the foF1 observations from Slough and Rome in order to investigate a possible relationship between the foF1 and the long-term variation of geomagnetic activity. A 40-year period, starting in 1962, has been used for the analysis. According to the results obtained earlier for F2 and E-region trends, geomagnetic control of the long-term variation has also been revealed for the foF1. Thus, it is now possible to speak about the geomagnetic control of the ionospheric trends in the whole ionosphere. This is not surprising as the Earth's ionosphere is a single entity that is strongly controlled, either directly or indirectly, by the magnetic field. As with the F2-region, this geomagnetic control is provided via neutral composition and temperature changes. A very long-term (centennial) increase in geomagnetic activity in the 20th century is seen in the long-term foF1 variations as well. After its removal, the residual foF1 trends are very small and insignificant. In principal, this means that the observed foF1 long-term variations have a natural origin and can be attributed to solar and geomagnetic activity long-term variations. However, the situation in the thermosphere has been changing since 1997 and available foF2 observations at the two stations reveal information about the "break down" of the geomagnetic control in the F2-region. Possible reasons of these changes are discussed.

Negative F2-layer storms related to geomagnetic activity and quiet-time disturbances (Q-disturbances) belong to different classes of events and exhibit different morphology. Mid-latitude daytime Q-disturbances, unlike the usual negative F2-layer storms, demonstrate NmF2 and hmF2 in-phase variations. An analysis of Millstone Hill ISR observations for usual and Q-disturbances has shown the difference in the controlling aeronomic parameter variations for the two classes of events. The decrease in atomic oxygen concentration provides the main contribution to the hmF2 decrease below the monthly median level during Q-disturbance events. Unlike the usual negative storms, the negative effect takes place in the whole topside ionosphere under Q-disturbance conditions. The difference is due to different effective plasma scale heights in the two cases. Clustering of the usual negative F2-layer disturbances around equinoxes and Q-disturbances around winter solstice, as well as different latitudinal variations for the occurrence of the two types of disturbances is due to their different formation mechanisms.

The observed NmF2 and NmE variations were analyzed for the periods of positive and negative quiet-time F2-layer disturbances (Q-disturbances) observed in the midlatitude daytime F2-layer to specify the mechanism of their origin. The noontime δNmF2 and δNmE deviations demonstrate a synchronous type of variation which can be explained by vertical gas motion in the thermosphere. This neutral gas motion should result in atomic abundance variations, the latter being confirmed by the Millstone Hill ISR observations for periods of positive and negative Q-disturbance events. The analysis of the ISR data has shown that atomic oxygen concentration variations are the main cause of the daytime F2-layer Q-disturbances. The auroral heating which controls the poleward thermospheric wind is considered to be the basic mechanism for the Q-disturbances, however, the specific mechanisms of positive and negative Q-disturbances are different. Some morphological features of the Q-disturbances revealed earlier are explained in the scope of the proposed concept.

A relationship between foE trends and geomagnetic activity long-term variations has been revealed for the first time. By analogy with earlier obtained results on the foF2 trends it is possible to speak about the geomagnetic control of the foE long-term trends as well. Periods of increasing geomagnetic activity correspond to negative foE trends, while these trends are positive for the decreasing phase of geomagnetic activity. This "natural" relationship breaks down around 1970 (on some stations later) when pronounced positive foE trends have appeared on most of the stations considered. The dependence of foE trends on geomagnetic activity can be related with nitric oxide variations at the E-layer heights. The positive foE trends that appeared after the "break down" effect may also be explained by the [NO] decrease which is not related to geomagnetic activity variations. But negative trends or irregular foE variations on some stations for the same time period require some different mechanism. Chemical pollution of the lower thermosphere due to the anthropogenic activity may be responsible for such abnormal foE behavior after the end of the 1960s.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances)

Storm effects at F1-layer heights (160–200 km) were analyzed for the first time using Millstone Hill (mid-latitudes) and EISCAT (auroral zone) incoherent scatter (IS) observations. The morphological study has shown both increases (positive effect) and decreases (negative effect) in electron concentration. Negative storm effects prevail for all seasons and show a larger magnitude than positive ones, the magnitude of the effect normally increasing with height. At Millstone Hill the summer storm effects are small compared to other seasons, but they are well detectable. At EISCAT this summer decrease takes place only with respect to the autumnal period and the autumn/spring asymmetry in the storm effects is well pronounced. Direct and significant correlation exists between deviations in electron concentration at the F1-layer heights and in the F2-layer maximum. Unlike the F2-layer the F1-region demonstrates a relatively small reaction to geomagnetic disturbances despite large perturbations in thermospheric parameters. Aeronomic parameters extracted from IS observations are used to explain the revealed morphology. A competition between atomic and molecular ion contributions to Ne variations was found to be the main physical mechanism controlling the F1-layer storm effect. The revealed morphology is shown to be related with neutral composition (O, O2, N2) seasonal and storm-time variations. The present day understanding of the F1-region formation mechanisms is sufficient to explain the observed storm effects.Key words. Atmospheric composition and structure (thermosphere-composition and chemistry); ionosphere (ion chemistry and composition; ionospheric disturbances)

An overall statistical study of night-time enhancements of NmF2 has been carried out. All available foF2 observations since 1955 at 53 ionosonde stations distributed worldwide in the latitude range fgeom = 15° - 60° were used in the analysis. More than 200 000 station-nights of data were analysed. This large data base allowed us to study seasonal, solar cycle and spatial variations of the NmF2 nighttime enhancements. Both pre-midnight and post-midnight NmF2 peaks demonstrate distinct variations with geophysical conditions, indicating different physical mechanisms responsible for their formation.Key words. Ionosphere (mid-latitude ionosphere, ionosphere-magnetosphere interactions) Radio science (ionospheric physics)

A new approach to extract foF2 long-term trends, which are free to a great extent from solar and geomagnetic activity effects, has been proposed. These trends are insensitive to the phase (increasing/decreasing) of geomagnetic activity, with long-term variations being small and insignificant for such relatively short time periods. A small but significant residual foF2 trend, with the slope Kr = - 2.2 × 10-4 per year, was obtained over a 55-year period (the longest avail-able) of observations at Slough. Such small trends have no practical importance. On the other hand, negative (although insignificant) residual trends obtained at 10 ionosonde stations for shorter periods (31 years) may be considered as a manifestation of a very long-term geomagnetic activity increase which did take place during the 20th century. All of the revealed foF2 long-term variations (trends) are shown to have a natural origin related to long-term variations in solar and geomagnetic activity. There is no indication of any manmade foF2 trends. Key words. Ionosphere (ionosphere-atmosphere interactions, ionospheric disturbances)

The purpose of this paper is to develop performance criteria for fleet selection in surface mining of lignin as a raw material for factory-made fuel. The East Siberian Biotechnical Plant (ESBP) proposes to close the Lignin Waste Storage (LWS) at Tulun, Irkutsk Region of Russia. The LWS is a 9.6 ha facility used for the long-term storage of hydrolysis lignin and some fly ash. The project provided whole-year open-pit mining of lignin storage with one mining ledge within 3 years. Productivity – 1500 t/day or 447 000 t/year. Excavated lignin will be stockpile on the Pellet Plant territory for later processing. Part of this closure effort would involve constructing an artificial reservoir on the place of LWS. The objectives of this project were as follows: determine equipment needs and develop optimal procedures for the lignin excavation and transportation. Lignin moving may include site preparation, excavation, transportation and road surfacing. Lignin excavation is conduct by using techniques similar to those used for open-pit mining of peat. For this project, the excavator is the most important piece of equipment required for lignin removal and handling. The mining process consist of excavating the lignin (using Kraneks ЕК-270LC) and hauling it to pellet plant via six off-road tractors&semitrailers (John Deere 7730& ISON-8520).

Equinoctial summer/winter transitions in the parameters of the F2-region are analyzed using ground-based ionosonde and incoherent scatter observations. Average transition from one type of diurnal NmF2 variation to another takes 20–25 days, but cases of very fast (6–10 days) transitions are observed as well. Strong day-time NmF2 deviations of both signs from the monthly median, not related to geomagnetic activity, are revealed for the transition periods. Both longitudinal and latitudinal variations take place for the amplitude of such quiet time NmF2 deviations. The summer-type diurnal NmF2 variation during the transition period is characterized by decreased atomic oxygen concentration [O] and a small equatorward thermospheric wind compared to winter-type days with strong poleward wind and increased [O]. Molecular N2 and O2 concentrations remain practically unchanged in such day-to-day transitions. The main cause of the F2-layer variations during the transition periods is the change of atomic oxygen abundance in the thermosphere related to changes of global thermospheric circulation. A possible relationship with an equinoctial transition of atomic oxygen at the E-region heights is discussed.Key words. Atmospheric composition and structure (thermosphere – composition and chemistry) – Ionosphere (ionosphere- atmosphere interactions; ionospheric disturbances)

Earlier revealed morphological features of the foF2 and hmF2 long-term trends are interpreted in the scope of the geomagnetic control concept based on the contemporary F2-layer storm mechanisms. The F2-layer parameter trends strongly depend on the long-term varying geomagnetic activity whose effects cannot be removed from the trends using conventional indices of geomagnetic activity. Therefore, any interpretation of the foF2 and hmF2 trends should consider the geomagnetic effects as an inalienable part of the trend analysis. Periods with negative and positive foF2 and hmF2 trends correspond to the periods of increasing or decreasing geomagnetic activity with the turning points around 1955, and the end of 1960s and 1980s, where foF2 and hmF2 trends change their signs. Such variations can be explained by neutral composition, as well as temperature and thermospheric wind changes related to geomagnetic activity variations. In particular, for the period of increasing geomagnetic activity (1965–1991) positive at lower latitudes, but negative at middle and high latitudes, foF2 trends may be explained by neutral composition and temperature changes, while soft electron precipitation determines nighttime trends at sub-auroral and auroral latitudes. A pronounced dependence of the foF2 trends on geomagnetic (invariant) latitude and the absence of any latitudinal dependence for the hmF2 trends are due to different dependencies of NmF2 and hmF2 on main aeronomic parameters. All of the revealed latitudinal and diurnal foF2 and hmF2 trend variations may be explained in the frame-work of contemporary F2-region storm mechanisms. The newly proposed geomagnetic storm concept used to explain F2-layer parameter long-term trends proceeds from a natural origin of the trends rather than an artificial one, related to the thermosphere cooling due to the greenhouse effect. Within this concept, instead of cooling, one should expect the thermosphere heating for the period of increasing geomagnetic activity (1965–1991).Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances)

The method earlier used for the foF2 long-term trends analysis is applied to reveal hmF2 long-term trends at 27 ionosonde stations in the European and Asian longitudinal sectors. Observed M(3000)F2 data for the last 3 solar cycles are used to derive hmF2 trends. The majority of the studied stations show significant hmF2 linear trends with a confidence level of at least 95% for the period after 1965, with most of these trends being positive. No systematic variation of the trend magnitude with latitude is revealed, but some longitudinal effect does take place. The proposed geomagnetic storm concept to explain hmF2 long-term trends proceeds from a natural origin of the trends rather than an artificial one related to the thermosphere cooling due to the greenhouse effect.Key words. Ionosphere (ionosphere-atmosphere interaction)

Physical interpretation is made of the O+/Ne diurnal variations in summer, revealed by Litvine et al. (1998) from the EISCAT observations. It is shown that the observed anti-correlation between the Z50 parameter, corresponding to the transition region between 50% of molecular and atomic ions, and the width Dz of the transition, defined as the altitude width between 10% and 90% of the O+/Ne ratio, can be reproduced in model calculations and the result of different recombination laws (quadratic in the lower and linear in the upper ionosphere) as well as diurnal variations in the photo-ionization rates.Key words.Ionosphere (ion chemistry and composition; modeling and forecasting)

The ionospheric sounding data at two southern hemisphere stations, the Argentine Islands and Port Stanley, are analyzed using a method previously developed by the authors. Negative trends of the critical frequency foF2 are found for both stations. The magnitudes of the trends are close to those at the corresponding (close geomagnetic latitude) stations of the northern hemisphere, as considered previously by the authors. The values of the F2 layer height hmF2 absolute trends ΔhmF2 are considered. The effect of ΔhmF2 dependence on hmF2 found by Jarvis et al. (1998) is reproduced. A concept is considered that long-term changes of the geomagnetic activity may be an important (if not the only) cause of all the trends of foF2 and hmF2 derived by several groups of authors. The dependence of both parameters on the geomagnetic index Ap corresponds to a smooth scheme of the ionospheric storm physics and morphology; thus, a principal cause of the foF2 and hmF2 geomagnetic trends is most probably a trend found in several publications in the number and intensity of ionospheric storms.Key words. Ionosphere (ionosphere-atmosphere interaction; ionospheric disturbances)

The mechanism of the NmF2 peak formation at different levels of solar activity is analyzed using Millstone Hill IS radar observations. The hmF2 nighttime increase due to thermospheric winds and the downward plasmaspheric fluxes are the key processes responsible for the NmF2 peak formation. The electron temperature follows with the opposite sign the electron density variations in this process. This mechanism provides a consistency with the Millstone Hill observations on the set of main parameters. The observed decrease of the nighttime NmF2 peak amplitude with solar activity is due to faster increasing of the recombination efficiency compared to the plasmaspheric flux increase. The E×B plasma drifts are shown to be inefficient for the NmF2 nighttime peak formation at high solar activity.Key words: Ionosphere (ionosphere-atmosphere interactions; mid-latitude ionosphere; plasma temperature and density)

There are differences between existing models of solar EUV with λ < 1050 Å and between laboratory measurements of the O+ + N2 – reaction rate coefficient, both parameters being crucial for the F2-region modeling. Therefore, indirect aeronomic estimates of these parameters may be useful for qualifying the existing EUV models and the laboratory measured O+ + N2 – rate coefficient. A modified self-consistent method for daytime F2-region modeling developed by Mikhailov and Schlegel was applied to EISCAT observations (32 quiet summer and equinoctial days) to estimate the set of main aeronomic parameters. Three laboratory measured temperature dependencies for the O+ + N2 – rate coefficient were used in our calculations to find self-consistent factors both for this rate coefficient and for the solar EUV flux model from Nusinov. Independent of the rate coefficient used, the calculated values group around the temperature dependence recently measured by Hierl et al. in the 850–1400 K temperature range. Therefore, this rate coefficient may be considered as the most preferable and is recommended for aeronomic calculations. The calculated EUV flux shows a somewhat steeper dependence on solar activity than both, the Nusinov and the EUVAC models predict. In practice both EUV models may be recommended for the F2-region electron density calculations with the total EUV flux shifted by ±25% for the EUVAC and Nusinov models, correspondingly.Key words: Ionosphere (ion chemistry and composition; ionosphere atmosphere interactions; modeling and forecasting)

A statistical analysis of two peaks (pre-midnight and post-midnight) occurrence in NmF2 daily variations was made on a latitudinal chain of four ionosonde stations in the Eurasian longitudinal sector. Overall 6182 cases of the first and 5600 cases of the second peak occurrence were analyzed using all available foF2 observations for the years of solar maximum and minimum. Well-pronounced and systematic variations with season and solar activity were revealed in the occurrence probability of the peaks, their amplitude and timing. The pattern of both peaks occurrence is similar during winter and equinoxes for midlatitude stations implying one and the same mechanism of their formation. The pre-midnight summer peak shows specific variations in particular during solar maximum pointing to a different mechanism controlling its appearance. Possible mechanisms of both peaks formation are discussed.Key words: Ionosphere (electric fields and currents; ionosphere-magnetosphere interactions; mid-latitude ionosphere)

Further development of the method proposed by Danilov and Mikhailov is presented. The method is applied to reveal the foF2 long-term trends on 30 Northern Hemisphere ionosonde stations. Most of them show significant foF2 trends. A pronounced dependence of trend magnitude on geomagnetic (invariant) latitude is confirmed. Periods of negative/positive foF2 trends corresponding to the periods of long-term increasing/decreasing geomagnetic activity are revealed for the first time. Pronounced diurnal variations of the foF2 trend magnitude are found. Strong positive foF2 trends in the post-midnight-early-morning LT sector and strong negative trends during daytime hours are found on the sub-auroral stations for the period with increasing geomagnetic activity. On the contrary middle and lower latitude stations demonstrate negative trends in the early-morning LT sector and small negative or positive trends during daytime hours for the same period. All the morphological features revealed of the foF2 trends may be explained in the framework of contemporary F2-region storm mechanisms. This newly proposed F2-layer geomagnetic storm concept casts serious doubts on the hypothesis relating the F2-layer parameter long-term trends to the thermosphere cooling due to the greenhouse effect.Key words: Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances)

Using a method suggested by the authors earlier, the long-term trends of the F2-layer critical frequency, foF2 are derived for a set of ionospheric stations with a wide latitudinal and longitudinal coverage. All the trends are found to be negative. A pronounced dependence on geomagnetic latitude is found, the trend magnitude increasing with the latter. No globe scale longitudinal effect in trends is detected. For the majority of the stations there is also a pronounced seasonal effect, the trend magnitude being higher in summer than in winter.Key words. Ionosphere (ionospheric disturbances; mid-latitude ionosphere)

During a nearby passage of the Active satellite above the Millstone Hill radar on 21 March 1990 at local sunset, the satellite and the radar performed simultaneous measurements of upper ionospheric parameters in nearly the same spatial volume. For this purpose the radar carried out a special azimuth-elevation scan to track the satellite. Direct comparisons of radar data and in situ satellite measurements have been carried out quite rarely. In this case, the coincidence of co-ordinated measurements and active ionospheric-magnetospheric processes during an extended storm recovery phase presents a unique occasion resulting in a very valuable data set. The measurements show generally good agreement both during quiet prestorm and storm conditions and the combination of radar and satellite observations gives a more comprehensive picture of the physical processes involved. We find a close relationship between the rapid westward ion drift peak at subauroral latitudes (SAID event) and the occurrence of a stable auroral red (SAR) arc observed after sunset by an all-sky imager and reported in an earlier study of this event. The SAID electric field is caused by the penetration of energetic ions with energies between about 1 keV and 100 keV into the outer plasmasphere to a latitude equatorward of the extent of the plasmasheet electrons. Charge separation results in the observed polarisation field and the SAID. Unusually high molecular ion densities measured by the satellite at altitudes of 700-870 km at subauroral and auroral latitudes point on strong upward-directed ion acceleration processes and an intense neutral gas upwelling. These structures are collocated with a narrow trough in electron density and an electron temperature peak as observed simultaneously by the radar and the satellite probes.Key words. Ionosphere (ionosphere-magnetosphere interactions; plasma temperature and density); Magnetospheric physics (plasmasphere).

A self-consistent method for day-time F2-region modelling was applied to the analysis of Millstone Hill incoherent scatter observations during the storm period of March 16-22, 1990. The method allows us to calculate in a self-consistent way neutral composition, temperature and meridional wind as well as the ionized species height distribution. Theoretically calculated Ne(h) profiles fit the observed daytime ones with great accuracy in the whole range of heights above 150 km for both quiet and disturbed days. The overall increase in Tex by 270 K from March 16 to March 22 reflects the increase of solar activity level during the period in question. A 30% decrease in [O] and a two-fold increase in [N2] are calculated for the disturbed day of March 22 relative to quiet time prestorm conditions. Only a small reaction to the first geomagnetic disturbance on March 18 and the initial phase of the second storm on March 20 was found in [O] and [N2] variations. The meridional neutral wind inferred from plasma vertical drift clearly demonstrates the dependence on the geomagnetic activity level being more equatorward on disturbed days. Small positive F2-layer storm effects on March 18 and 20 are totally attributed to the decrease in the northward neutral wind but not to changes in neutral composition. A moderate (by a factor of 1.5) O/N2 ratio decrease relative to the MSIS-83 model prediction is required to describe the observed NmF2 decrease on the most disturbed day of March 22, but virtually no change of this ratio is needed for March 21.

Ground-based ionosonde and magnetic-field observations on the equatorial station Huancayo, ESRO4 neutral-composition measurements, and theoretical model calculations were used to analyze disturbed E×B vertical plasma drift during the phase of solar minimum in 1973. Vertical drifts calculated for disturbed days do not show the systematic decrease often mentioned in publications, and demonstrate strong dependence on IMF-Bz changes. It is confirmed with the help of our drift calculations that Bz turnings to a northward direction result in a decrease (up to reversal) of normal Sq (eastward during daytime and westward at nighttime) in the zonal component of electric field. Southward Bz excursions enhance normal Ey both in daytime and nighttime hours. Model predictions of Ey\'s reaction to IMF-Bz changes are discussed.

Daytime F2-layer positive storm effects at middle and lower latitudes in the winter thermosphere are analyzed using AE-C, ESRO-4 neutral gas composition data, ground-based ionosonde observations and model calculations. Different longitudinal sectors marked by the storm onset as 'night-time' and 'daytime' demonstrate different F2-layer positive storm mechanisms. Neutral composition changes in the 'night-time' sector with increased [O] and [N2] absolute concentrations, while (N2/O)storm/(N2/O)quiet\approx1 at F2-layer heights, are shown to contribute largely to the background NmF2 increase at lower latitudes lasting during daytime hours. Storm-induced surges of the equatorward wind give rise to an additional NmF2 increase above this background level. The mid-latitude F2-layer positive storm effect in the 'daytime' sector is due to the vertical plasma drift increase, resulting from the interaction of background (poleward) and storm-induced (equatorward) thermospheric winds, but not to changes of [O] and [N2] concentrations.

In article results of experiments on creation of coal and peat fuel compositions for burning in solid-fuel boilers are described. The main objective of research consisted in development of combination of coal dust and natural peat without binding additives. The role of peat consists that it increases efficiency of process of granulation, being natural binding. The method of granulation allows to utilize waste of the coal industry. Joint burning of two types of fuel – coal dust and peat reduces emission of sulfur dioxides. The cost of peat raw materials is lower, than artificial binding, applied to briquetting of coal dust. The composition of mix of coal dust and peat varied in the ratio 2:1, 1:1 and 1:2 in volume ratio at humidity of mix before extrusion of 65 %. In the course of preparatory operations of coal raw materials its crushing and sifting through sieve of 24 mesh (0,707 mm) was carried out. Procedure of hashing of samples of coal and peat was carried out before receiving homogeneous mixture. After hashing mix was located in piston press for receiving granules. Coal dust and wet peat pass semifixed extrusion on piston press with formation of cylindrical granules with a diameter of 16 mm. After extrusion of granule are dried to operational humidity of 25 %. Coal and peat fuel granules showed sufficient mechanical strength for transportation and power feed in solid-fuel boilers. Burning of coal and peat fuel granules in vitro at temperature of 800 °C does not lead to ashes agglomeration. The conducted preliminary researches showed prospects of utilization of coal waste by granulation method in mix with natural peat.

Theoretical model calculations along with ground-based observations from Huancayo ionosonde station and ESRO-4 gas analyzer data, were used to estimate the contribution of neutral gas composition changes and E×B vertical plasma drift to the observed F2-layer storm effects at the geomagnetic equator. Atomic oxygen concentration increase may give the main contribution to the positive NmF2 effect when drift velocity changes are small, but negative storm effects, on the other hand, are related mostly to vertical drift variations.

The first part of the paper is directed to the investigation of the practical importance of possible longterm trends in the F2-layer for ionospheric prediction models. Using observations of about 50 different ionosonde stations with more than 30 years data series of foF2 and hmF2, trends have been derived with the solar sunspot number R12 as index of the solar activity. The final result of this trend analysis is that the differences between the trends derived from the data of the individual stations are relatively large, the calculated global mean values of the foF2 and hmF2 trends, however, are relatively small. Therefore, these small global trends can be neglected for practical purposes and must not be considered in ionospheric prediction models. This conclusion is in agreement with the results of other investigations analyzing data of globally distributed stations. As shown with the data of the ionosonde station Tromsø, however, at individual stations the ionospheric trends may be markedly stronger and lead to essential effects in ionospheric radio propagation. The second part of the paper deals with the reasons for possible trends in the Earths atmo- and ionosphere as investigated by different methods using characteristic parameters of the ionospheric D-, E-, and F-regions. Mainly in the F2-region different analyses have been carried out. The derived trends are mainly discussed in connection with an increasing greenhouse effect or by long-term changes in geomagnetic activity. In the F1-layer the derived mean global trend in foF1 is in good agreement with model predictions of an increasing greenhouse effect. In the E-region the derived trends in foE and h´E are compared with model results of an atmospheric greenhouse effect, or explained by geomagnetic effects or other anthropogenic disturbances. The trend results in the D-region derived from ionospheric reflection height and absorption measurements in the LF, MF and HF ranges can at least partly be explained by an increasing atmospheric greenhouse effect.

Height distribution of ionospheric plasma parameters in the F2-region is closely related to height distribution of the main thermospheric parameters. Therefore, they can be extracted from ionospheric observations solving an inverse problem of aeronomy. A self-consistent approach to the Ne(h) modeling at the F2-region heights has been applied to solve the problem. Using routine incoherent scatter radar observations (Ne(h), Te(h), Ti(h), Vi(h) profiles) the method yields a self-consistent set of main aeronomic parameters responsible for the F2-region formation. The list of derived parameters includes: neutral temperature profile Tn(h) depending on the exospheric temperature Tex, the temperature at 120 km T120 and the shape-parameter S, which determine the temperature profile, concentration of neutral species [O], [O2], [N2], vertical plasma drift W, which may be converted to the meridional thermospheric wind Vnx, total solar EUV flux and ion composition (O+, O2 +, NO+, N2 +, N+) as a result of Ne(h) fitting. Therefore, the method gives a complete description of the upper atmosphere condition in the vicinity of incoherent scatter facility for the periods of observation. Analysis of all available EISCAT (CP-1, CP-2) observations has shown wide deviations from MSIS-86 model predictions for geomagnetically disturbed conditions while the retrieved parameters are close to the model ones for quiet periods. The approach turns out to be very useful for physical analyses of the F2-layer disturbance mechanisms giving a complete picture of the phenomenon in question. Limitations and problems related to method application are discussed. Under existing conditions when thermospheric observations are not conducted currently the proposed method may be considered a real tool for thermosphere investigation and monitoring at least for the periods of ISR observations.

Monthly median f0F2 and M(3000)F2 ionospheric model, MQMF2, based on the multiquadric (MQ) method of spatial interpolation and a new ionospheric index MF2 describes the monthly median f0F2 and M(3000)F2 over Europe for any UT moment, month and level of solar activity. The multiquadric method allows a surface to be drawn strictly over a given set of points unlike many other currently used ionosphere mapping methods. A non-linear dependence of f0F2 and M(3000)F2 on solar activity level (expressed by MF2 index) is used to establish local models for each ionosonde station. Observations on 28 ionosondes for f0F2 and 19 for M(3000)F2 over 10-30 years were used for model derivation. The MQMF provides better accuracy than the CCIR model in retrospective mode over Europe. Long-term f0F2 prediction with the help of MF2 index for the rising part of solar cycle 22 is shown to provide better prediction accuracy than the CCIR model based on sunspot number R12. MQMF2 is implemented as a code for PC AT-386/387 or compatible, providing tables, plots and maps.

Monthly median empirical models IRI-95 and NeUoG were compared with incoherent scatter EISCAT and Millstone Hill observations as well as with El Arenosillo Digisonde N e (h) bottomside profiles. A comparison was made for various seasons, levels of solar activity, daytime and night-time hours. The results on the topside comparison: 1) the IRI-95 model systematically and strongly overestimates the Ne (h) effective scale height both for daytime and night-time periods especially during maximum and middle solar activity both at EISCAT and Millstone Hill; 2) the NeUoG model on the contrary systematically underestimates the scale height at all levels of solar activity. But the NeUoG model provides much better overall agreement with SD being less by a factor of 1.5-1.7 in comparison with the IRI-95 model results. The results on the bottom-side comparison: 1) the IRI-95 accuracy is different for daytime and night-time hours, being much worse for the night-time; 2) the NeUoG model similar to IRI-95 demonstrates much worse accuracy for the night-time hours; 3) the NeUoG model demonstrates no advantages over the IRI-95 model in the bottomside N e (h) description. A new simple TopN e model for the N e (h) topside distribution based on the EISCAT and Millstone Hill observations is proposed. The model is supposed to be normalized by the observed hmF 2 and NmF 2 values and is valid below a 600 km height. The TopN e model provides good approximation accuracy over EISCAT and Millstone Hill observations. A comparison with the independent Intercosmos-19 topside sounder observations is given.

Ionosphere monitoring implies: observations, prediction and mapping of ionospheric parameters. A case with one available (El Arenosillo) ionosonde is considered. Some statistical methods for f0F2 short-term (1-24 h in advance) prediction are compared. The analysis of multi-dimensional regression for Df0F2 (relative deviation from running median) with Ap, F10.7 and previous Df0F2 observations has shown that inclusion of additional terms with Ap and F10.7 improves the prediction accuracy for lead time more than 15 h. For lead time 1-6 h a linear regression with earlier observed Df0F2 provides the f0F2 forecast with Relative Mean Deviation (RMD) 6-11%. This is acceptable from a practical point of view. A 24-h forecast can be done with RMD 10-11%. Multi-regressional methods provide better prediction accuracy than the usual 10-day running median or quasi-inertial method based on such median. Hourly f0F2 values may be used to calculate the effective index R12eff used as input to the ITU-R monthly median model. This allows the ITU-R model to "breathe" following hour-to-hour f0F2 variations. Then standard surfering methods may be applied for f0F2 mapping over the whole area. The f0F2 mapping accuracy based on the hourly R12eff index is shown to be 9-11% depending on solar activity level.

Seasonal variations of hmE and f0F2 are analyzed using El Arenosillo digisonde observations during solar minimum (1995-1996). Unlike some widely used empirical models daytime hmE show seasonal variations with winter hmE being higher than summer ones and seasonal differences increase with solar zenith angle. Model calculations enable us to reproduce the observed hmE seasonal variations but the calculated daytime f0E values are too low if conventional EUV fluxes and dissociative recombination rate constants are used. A reduction of a (NO+ ) by taking into account Te > Tn in the E-region as it follows from probe measurements seems to be a plausible solution. The E-region ion composition corresponding to rocket observations may be obtained in model calculations using an appropriate [NO] height distribution. Calculated summer concentrations of [NO] are by a factor of 3-4 larger than winter ones at the hmE-heights.

Ground-based ionosonde and magnetic-field observations on the equatorial station Huancayo, ESRO4 neutral-composition measurements, and theoretical model calculations were used to analyze disturbed E×B vertical plasma drift during the phase of solar minimum in 1973. Vertical drifts calculated for disturbed days do not show the systematic decrease often mentioned in publications, and demonstrate strong dependence on IMF-Bz changes. It is confirmed with the help of our drift calculations that Bz turnings to a northward direction result in a decrease (up to reversal) of normal Sq (eastward during daytime and westward at nighttime) in the zonal component of electric field. Southward Bz excursions enhance normal Ey both in daytime and nighttime hours. Model predictions of Ey's reaction to IMF-Bz changes are discussed.

Daytime F2-layer positive storm effects at middle and lower latitudes in the winter thermosphere are analyzed using AE-C, ESRO-4 neutral gas composition data, ground-based ionosonde observations and model calculations. Different longitudinal sectors marked by the storm onset as 'night-time' and 'daytime' demonstrate different F2-layer positive storm mechanisms. Neutral composition changes in the 'night-time' sector with increased [O] and [N2] absolute concentrations, while (N2/O)storm/(N2/O)quietapprox1 at F2-layer heights, are shown to contribute largely to the background NmF2 increase at lower latitudes lasting during daytime hours. Storm-induced surges of the equatorward wind give rise to an additional NmF2 increase above this background level. The mid-latitude F2-layer positive storm effect in the 'daytime' sector is due to the vertical plasma drift increase, resulting from the interaction of background (poleward) and storm-induced (equatorward) thermospheric winds, but not to changes of [O] and [N2] concentrations.

Theoretical model calculations along with ground-based observations from Huancayo ionosonde station and ESRO-4 gas analyzer data, were used to estimate the contribution of neutral gas composition changes and E×B vertical plasma drift to the observed F2-layer storm effects at the geomagnetic equator. Atomic oxygen concentration increase may give the main contribution to the positive NmF2 effect when drift velocity changes are small, but negative storm effects, on the other hand, are related mostly to vertical drift variations.