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Petrozavodsk, Russia

Gerasimov Y.,Finnish Forest Research Institute | Katarov V.,Petrozavodsk State University
Croatian Journal of Forest Engineering | Year: 2010

A study of the effect of bogie wheel track and slash reinforcement on the sinkage (as rut depth) and soil compaction (as bulk density) of silt loam soil was carried out in spring and autumn at two harvesting sites in Russia. A Ponsse ELK forwarder loaded with 16 m3 of timber, fitted and unfitted with bogie tracks, was repeatedly driven on forest soil for 1-10 passes. The degree of sinkage and soil compaction was measured at two soil moisture contents: moist (W = 80%) and wet (W = 93%) after each pass. A John Deere 1410 forwarder loaded with 16 m3 of timber, and fitted and unfitted with bogie tracks, was driven on forest soil covering a 15 kg/m2 slash layer for 1-10 passes. The degree of soil compaction was measured at moist soil (moisture content W = 88%). The results indicated that on forest silt loam soil the bogie track decreases sinkage in comparison with a conventional wheel with a tire: the maximum rut depths reached were 0.48 m vs. 0.71 m (-0.23 m) on wet and 0.22 m vs. 0.40 m (-0.18 m) on moist soils by the 10th pass (160 m 3 of extracted timber), respectively. The track influence on soil compaction varied and was mixed. Bulk density increased up to 1.30 g/cm 3 vs. 1.24 g/cm3 (+0.06 g/cm3) on moist soil and it was almost the same on wet soil by the 10th pass, respectively. The slash reinforcement constrained rut-forming and soil compaction after all forwarder passes. Cubic regressions between average rut depth and bulk density and cumulative volume of extracted timber were derived for forest silt loam soil with different moisture contents. Bogie track and particularly slash reinforcement are necessary for environmentally sensitive wood harvesting by the CTL system on soft soils. Source

Pergament A.,Petrozavodsk State University
Phase Transitions | Year: 2010

On the basis of the Ashcroft empty core model potential, the equation for the constant of Coulomb interaction in the theory of excitonic insulator is modified. It is shown that in this case the dependence of the energy gap width on the charge carrier density obeys the Mott criterion in the limit of low densities. The conformity of the theory with some experimental data concerning metal-insulator phase transitions in doped semiconductors and transition metal compounds is discussed. © 2010 Taylor & Francis. Source

Singh V.K.,Bundelkhand University | Slabunov A.,Petrozavodsk State University
International Geology Review | Year: 2015

Analysis of 3.3 Ga tonalite-trondhjemite-granodiorite (TTG) series granitoids and greenstone belt assemblages from the Bundelkhand craton in central India reveal that it is a typical Archaean craton. At least two greenstone complexes can be recognized in the Bundelkhand craton, namely the (i) Central Bundelkhand (Babina, Mauranipur belts) and (ii) Southern Bundelkhand (Girar, Madaura belts). The Central Bundelkhand greenstone complex contains three tectonostratigraphic assemblages: (1) metamorphosed basic or metabasic, high-Mg rocks; (2) banded iron formations (BIFs); and (3) felsic volcanics. The first two assemblages are regarded as representing an earlier sequence, which is in tectonic contact with the felsic volcanics. However, the contact between the BIFs and mafic volcanics is also evidently tectonic. Metabasic high-Mg rocks are represented by amphibolites and tremolite-actinolite schists in the Babina greenstone belt and are comparable in composition to tholeiitic basalts-basaltic andesites and komatiites. They are very similar to the metabasic high-Mg rocks of the Mauranipur greenstone belt. Felsic volcanics occur as fine-grained schists with phenocrysts of quartz, albite, and microcline. Felsic volcanics are classified as calc-alkaline dacites, less commonly rhyolites. The chondrite-normalized rare earth element distribution pattern is poorly fractionated (LaN/LuN = 11-16) with a small negative Eu anomaly (Eu/Eu∗ = 0.68-0.85), being characteristic of volcanics formed in a subduction setting. On Rb - Y + Nb, Nb - Y, Rb - Ta + Yb and Ta - Yb discrimination diagrams, the compositions of the volcanics are also consistent with those of felsic rocks formed in subduction settings. SHRIMP-dating of zircon from the felsic volcanics of the Babina belt of the Central Bundelkhand greenstone complex, performed for the first time, has shown that they were erupted in Neoarchaean time (2542 ± 17 Ma). The early sequence of the Babina belt is correlatable with the rocks of the Mauranipur belt, whose age is tentatively estimated as Mesoarchaean. The Central Bundelkhand greenstone complex consists of two (Meso- and Neoarchaean) sequences, which were formed in subduction settings. © 2014 © 2014 Taylor & Francis. Source

The condition of simulated or real manned spaceflight, i.e. thermally comfortable microgravitation (G∼ 0), is very similar to the intrauterine immersion to the amniotic fluid. Domination of fast muscle fibers and phasic movements forms the fetal strategy to survive in heating, strongly hypoxic, albeit normal for fetus, immersion. In adults, the adaptive response separately to microgravitation, heat stress and hypoxia also shifts muscle fiber properties to faster values. That allows to speculate about specific motor strategy induced by micro-or hypogravitation (fetal/. microgravitation, or FM-strategy).After birth the newborn is subjected to a combined 'sensory attack' of Earth gravitation, cooler ambient temperature and normoxia which is actually hyperoxic for fetus. The process of parturition can be considered as equivalent to cosmonaut's/astronaut's transition from microgravitation back to Earth gravitation (G= 1) during landing. These factors also act simultaneously and constitute another set of sensory inputs with the effect that is opposite to the intrauterine condition. In normal gravitation, comfortable temperature and normoxia decreases the motor unit activity (MU) firing rate to a level, characteristic for the regular Earth condition. In contrast to 'faster' fetal adaptive motor response (microgravitation, heat, hypoxia), the post-natal adult set of conditions (lower, but still normal temperature, normoxia, 1. G gravitation, healthy maturation) may represent the 'Earth' adaptive motor response, or the (gravitation/. Earth, or GE-strategy). The motor system undergoes a second profound remodeling in older people during healthy ageing that results in further domination of slow muscle fibers and slowing down motor unit activity, simulating the condition of hypergravitation (G> 1). Similar slowing adaptive responses are represented by cold and hyperoxia thus forming further motor strategy that could be named as SJ-strategy (after 'slow' and Jupiter - the most massive planet and the only planet with G> 1 in the solar system).These strategies suppose that definite sensory inputs and conditions may substitute each other due to its equivalent action on the motor system. Thus, cold 'sensory attack' may serve as a 'surrogate' for gravitation because these two conditions exert equivalent stimulating action on muscle tone. In that respect long-term mild cooling exposures or shorter severe cold exposures may be considered as a prophylactic countermeasure against hazardous action of weightlessness. Also, combination of cooling sensory intervention with traditional and well- documented interventions (whole body vibration and stimulation of 'support zone' afferents) may elevate their anti-microgravitation efficiency. © 2012 Elsevier Ireland Ltd. Source

Here we describe GATO (gravity, age, thermoregulation, and oxygenation) hypothesis (or a "Baby Astronaut" hypothesis) which we suggest to explain synergistic effect of these factors on the motor system. Taken separately, microgravity (in spaceflight, G ∼ 0), the early age, heat and hypoxia exert identical effect on the motor system. We posit that synergy of these factors originate from their synchronicity during intrauterine immersion (analog microgravity) of the fetus in warm hypoxic condition. We further postulate three successive motor adaptive strategies, driven lifelong by gravity as the key factor. The first by age, fetal/microgravity (FM)-strategy, induced by the intrauterine immersion of the fetus, is based on domination of fast type muscle fibers. After birth, thought to be analog for landing from orbit, newborn is subjected to combined influence of cooler ambient temperature, normoxia, and 1G Earth gravity, which cooperatively form a slower GE-strategy. Eventually, healthy ageing results in further domination of slow type muscle fibers that forms the slowest (SL)-strategy. Our hypothesis implies that specific sensory conditions may substitute for each other owing to their synergistic action on the motor system. According to GATO hypothesis heating and hypoxia may be considered as "pro-microgravity" factors, while cold and hyperoxia - as "pro-gravity" ones. As such, cold may act as a partial "surrogate" for gravity, estimated as ∼0.2. G. That may have potential to elaborate countermeasures for muscle atrophy in astronauts either on-board in long-term spaceflight or for post-flight rehabilitation. Based on GATO hypothesis, predictions on muscle remodeling caused by illumination, sound/noise, and gravidity are discussed. © 2012 Elsevier Ltd. Source

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