On the Structure of Symplectic Mappings. The Fast Lyapunov Indicator: a Very Sensitive Tool

It is already known (Froeschlé, Lega and Gonczi, 1997) that the Fast Lyapunov Indicator (FLI), that is the computation on a relatively short time of the largest Lyapunov indicator, allows to discriminate between ordered and weak chaotic motion. We have found that, under certain conditions, the FLI also discriminates between resonant and non-resonant orbits, not only for two-dimensional symplectic mappings but also for higher dimensional ones. Using this indicator, we present an example of the Arnold web detection for four and six-dimensional symplectic maps. We show that this method allows to detect the global transition of the system from an exponentially stable Nekhoroshevs like regime to the diffusive Chirikovs one.     

3D structure of the Earth's crust beneath the northern part of the Bohemian Massif

The SUDETES 2003 wide-angle refraction/reflection experiment covered the area of the south-western Poland and the northern Bohemian Massif. The good quality data that were gathered combined with the data from previous experiments (POLONAISE'97, CELEBRATION 2000) allowed us to prepare a 3D seismic model of the crust and uppermost mantle for this area. We inverted travel times of both refracted and reflected P waves using the JIVE3D package. This allowed us to obtain a model of P-wave velocity distribution as well as the shape of major boundaries in the crust. We also present a detailed uncertainty analysis for both the boundary depths and the velocity field. In doing the uncertainty analysis we found an interesting, strong dependence between uncertainty and inversion scheme (order of used phases). We also compared the model with surface geology and found good correlation between velocity inhomogeneities in the uppermost crust (down to 2 km) and major geological units. The higher velocity lower crust (6.9–7.2 km/s) could result from remelting of the lower crust or magmatic underplating.     

Reconstructions of spring/summer precipitation for the Eastern Mediterranean from tree-ring widths and its connection to large-scale atmospheric circulation

This study represents the first large-scale systematic dendroclimatic sampling focused on developing chronologies from different species in the eastern Mediterranean region. Six reconstructions were developed from chronologies ranging in length from 115 years to 600 years. The first reconstruction (1885–2000) was derived from principal components (PCs) of 36 combined chronologies. The remaining five, 1800–2000, 1700–2000, 1600–2000, 1500–2000 and 1400–2000 were developed from PCs of 32, 18, 14, 9, and 7 chronologies, respectively. Calibration and verification statistics for the period 1931–2000 show good levels of skill for all reconstructions. The longest period of consecutive dry years, defined as those with less than 90% of the mean of the observed May–August precipitation, was 5 years (1591–1595) and occurred only once during the last 600 years. The longest reconstructed wet period was 5 years (1601–1605 and 1751–1755). No long term trends were found in May–August precipitation during the last few centuries. Regression maps are used to identify the influence of large-scale atmospheric circulation on regional precipitation. In general, tree-ring indices are influenced by May–August precipitation, which is driven by anomalous below (above) normal pressure at all atmospheric levels and by convection (subsidence) and small pressure gradients at sea level. These atmospheric conditions also control the anomaly surface air temperature distribution which indicates below (above) normal values in the southern regions and warmer (cooler) conditions north of around 40°N. A compositing technique is used to extract information on large-scale climate signals from extreme wet and dry summers for the second half of the twentieth century and an independent reconstruction over the last 237 years. Similar main modes of atmospheric patterns and surface air temperature distribution related to extreme dry and wet summers were identified both for the most recent 50 years and the last 237 years. Except for the last few decades, running correlation analyses between the major European-scale circulation patterns and eastern Mediteranean spring/summer precipitation over the last 237 years are non-stationary and insignificant, suggesting that local and/or sub-regional geographic factors and processes are important influences on tree-ring variability over the last few centuries.     

Land Cover Change Characteristics of North-South Transect in Northeast Asia from 2001 to 2012

Northeast Asia is an area with relative concentrations of resources, a complex ecological environment pattern, and a marked human-land contrast relationship. This area has significance for analyzing land cover patterns and variations for regional sustainable development among the trans-boundary areas of China, Russia, and Mongolia. In this paper, the transect analysis research tool and transfer matrix method are used to capture the regional land cover change characteristics by using Moderate Resolution Imaging Spectroradiometer(MODIS) datasets recorded from 2001 to 2012.The spatial distribution results show that forests have increased dramatically, cropland increased marginally, and grassland and shrubs decreased totally. The inter-annual variation, results show a steady and slowly increasing trend for grassland and shrubs, dramatic fluctuation features with an increasing trend for forest land, and zigzag wave changing characteristic for cropland. The total land use dynamic degree (TLUDD)was steady, with an overall slightly increasing trend.     

Interglacial History of a Palaeo-lake and Regional Environment: A Multi-proxy Study of a Permafrost Deposit from Bol’shoy Lyakhovsky Island, Arctic Siberia

Chironomid, pollen, and rhizopod records from a permafrost sequence at Bol’shoy Lyakhovsky Island (New Siberian Archipelago) document the development of a thermokarst palaeo-lake and environmental conditions in the region during the last Interglacial (MIS 5e). Open Poaceae and Artemisia associations dominated vegetation at the beginning of the interglacial period. Rare shrub thickets (Salix, Betula nana, Alnus fruticosa) grew in more protected and wetter places as well. Saalian ice wedges started to melt during this time, resulting in the formation of an initial thermokarst water body. The high percentage of semi-aquatic chironomids suggests that a peatland-pool initially existed at the site. A distinct decrease in semi-aquatic chironomid taxa and an increase in lacustrine ones point to a gradual pooling of water in the basin, which could in turn induce thermokarst and create a permanent pond during the subsequent period. The highest relative abundance of Chironomus and Procladius reflects unfrozen water remaining under the ice throughout the ice-covered period during the later stage of palaeo-lake development. The chironomid record points to three successive stages during the history of the lake: (1) a peatland pool; (2) a pond (i.e., shallower than the maximum ice-cover thickness); and (3) a shallow lake (i.e., deeper than the maximum ice-cover thickness). The trend of palaeo-lake development indicates that intensive thermokarst processes occurred in the region during the last Interglacial. Shrub tundra communities with Alnus fruticosa and Betula nana dominated the vegetation during the interglacial optimum. The climate was moister and warmer than present. The results of this study suggest that quantitative chironomid-based temperature reconstructions from Arctic thermokarst ponds/lakes may be problematic due to other key environmental factors, such as prolonged periods of winter anoxia and local hydrological/geomorphological processes, controlling the chironomid assemblages.     

Assessment of the acid drainage neutralization capacity and the toxic metals lixiviation of tailing from Guanajuato mining district,Mexico

In Mexico, many environmental problems are generated by large mining activities taking place in several mining districts. These mining activities produce great quantities of residues; large majorities of these have high sulfur content, which could generate acid drainage due to their interaction with the oxygen in the environment. The study area was located in the Mining District of Guanajuato, Mexico with abandoned tailings generated mainly by the gold and silver production. Two areas, called as Monte de San Nicolás (SN) and Peregrina (P) were selected for this study. The results study shows that there was no risk of production of acid drainage, since these tailings contained high amount of carbonates, which neutralized the generation of acidity and consequently decreased the possibility of leaching of some elements. However, not all elements leach in acid pH, as arsenic bound to oxyhydroxides, which is in a basic environment and its increased release by increasing the pH.     

Origin of V. Grib pipe eclogites (Arkhangelsk region,NW Russia): geochemistry,Sm-Nd and Rb-Sr isotopes and relation to regional Precambrian tectonics

Mineralogy and Petrology - In this paper, new main and trace elements and isotopic data are presented for 14 coarse-grained eclogite xenoliths from the V. Grib kimberlite pipe in the central part...     

Soil acidity adaptive control problem

Problem of soil acidity regularization is modeled as stochastic adaptive control problem with a linear difference equation of the dynamics of a field pH level. Stochastic component in the equation represents an individual time variability of soil acidity of an elementary section. We use Bayesian approach to determine a posteriori probability density function of the unknown parameters of the stochastic transition process. The Kullback–Leibler information divergence is used as a measure of difference between true distribution and its estimation. Algorithm for the construction of an adaptive stabilizing control in such a linear control system is proposed in the paper. Numerical realization of the algorithm is represented for a problem of a field soil acidity control.