Three-body dynamics: intermittent chaos with strange attractor     

Pekka Heinämäki  Harry J. Lehto  Mauri J. Valtonen  & Arthur D. Chernin 《Monthly notices of the Royal Astronomical Society》1998,298(3):790-796

We have studied the structure of chaos in three-body dynamics using the concept of intermittency, implying that violent states of a system alternate in time with quasi-regular states producing together a non-stationary and evolving pattern of unpredictable behaviour. Computer simulations are produced to demonstrate explicitly sporadic short violent bursts in quasi-regular hierarchical states of the systems. This is seen both in orbits and in the long time series generated by the system. The time series prove to be similar in shape to what is observed in various physical experiments with laboratory chaotic systems when they reveal the so-called type-III intermittency. The new effective methods of time series analysis enable us to discover a strange attractor with a fractal dimension slightly above 2. This shows that three-body dynamics has the same intrinsic qualitative structure and quantitative measure of chaos as the widely known chaotic system, the Lorenz attractor.  相似文献   

Technogenic hydrogeochemical anomalies of tungsten deposits in Kykylbey ore region     

Leonid V.Zamana  Larisa P.Chechel 《世界地质(英文版)》2004,7(1)

Peculiarities of the tungsten deposits drainage flow chemical composition formation, the development of which was ceased almost 40 years ago, have been considered. Migration peculiarities of ore components have been covered, and forms of their migration have been calculated. Inertial characteristics of the surface flow contamination are shown.  相似文献   

Impact of different energies of precipitating particles on NOx generation in the middle and upper atmosphere during geomagnetic storms     

Esa Turunen  Pekka T. Verronen  Annika Seppälä  Craig J. Rodger  Mark A. Clilverd  Johanna Tamminen  Carl-Fredrik Enell  Thomas Ulich 《Journal of Atmospheric and Solar》2009,71(10-11):1176-1189

Energetic particle precipitation couples the solar wind to the Earth's atmosphere and indirectly to Earth's climate. Ionisation and dissociation increases, due to particle precipitation, create odd nitrogen (NO_x) and odd hydrogen (HO_X) in the upper atmosphere, which can affect ozone chemistry. The long-lived NO_x can be transported downwards into the stratosphere, particularly during the polar winter. Thus, the impact of NO_x is determined by both the initial ionisation production, which is a function of the particle flux and energy spectrum, as well as transport rates. In this paper, we use the Sodankylä Ion and Neurtal Chemistry (SIC) model to simulate the production of NO_x from examples of the most representative particle flux and energy spectra available today of solar proton events (SPE), auroral energy electrons, and relativistic electron precipitation (REP). Large SPEs are found to produce higher initial NO_x concentrations than long-lived REP events, which themselves produce higher initial NO_x levels than auroral electron precipitation. Only REP microburst events were found to be insignificant in terms of generating NO_x. We show that the Global Ozone Monitoring by Occultation of Stars (GOMOS) observations from the Arctic winter 2003–2004 are consistent with NO_x generation by a combination of SPE, auroral altitude precipitation, and long-lived REP events.  相似文献   

Carbon monoxide in low-mass dwarf stars     

Hugh R. A. Jones  Yakiv Pavlenko  Serena Viti  R. J. Barber  Larisa A. Yakovina  David Pinfield  Jonathan Tennyson 《Monthly notices of the Royal Astronomical Society》2005,358(1):105-112

We compare high-resolution infrared observations of the CO 2–0 bands in the 2.297–2.310 μm region of M dwarfs and one L dwarf with theoretical expectations. We find a good match between the observational and synthetic spectra throughout the 2000–3500 K temperature regime investigated. None the less, for the 2500–3500 K temperature range, the temperatures that we derive from synthetic spectral fits are higher than expected from more empirical methods by several hundred kelvin. In order to reconcile our findings with the empirical temperature scale, it is necessary to invoke warming of the model atmosphere used to construct the synthetic spectra. We consider that the most likely reason for the back-warming is missing high-temperature opacity due to water vapour. We compare the water vapour opacity of the Partridge–Schwenke line list used for the model atmosphere with the output from a preliminary calculation by Barber & Tennyson. While the Partridge–Schwenke line list is a reasonable spectroscopic match for the new line list at 2000 K, by 4000 K it is missing around 25 per cent of the water vapour opacity. We thus consider that the offset between empirical and synthetic temperature scales is explained by the lack of hot water vapour used for computation of the synthetic spectra. For our coolest objects with temperatures below 2500 K, we find best fits when using synthetic spectra which include dust emission. Our spectra also allow us to constrain the rotational velocities of our sources, and these velocities are consistent with the broad trend of rotational velocities increasing from M to L.  相似文献   

Mikulino and Valdai palaeoenvironments in the Vologda area, NW Russia     

Valery Gey  Matti Saarnisto  Juha Pekka Lunkka  Igor Demidov 《Global and Planetary Change》2001,31(1-4)

Nine representative sediment sequences and pollen diagrams obtained during the Quaternary mapping programme carried out by the Geological Expedition (St. Petersburg, Russia) between 1960s and 1980s are presented from the Vologda area, NW Russian Plain, covering the time span from the Moscow cold (Saale) stage into the Late Valdai (Weichsel) substage. This work was done in order to shed light on the evolution of palaeoenvironments, vegetation and climate in the area. The results suggest that two major depressions in the Vologda area, namely the Mologa–Sheksnian and Prisukhonian basins, witnessed lake level fluctuations that were most likely closely linked to climatic fluctuations. It is suggested that during the Mikulino (Eem) thermal optimum most of the lowland areas were dry land. However, during the Early and Middle Valdai, the large depressions started to flood as a result of wet and cold climate. This caused the accumulation of lacustrine and also lacustrine–alluvial and lacustrine–bog sediments into the basins. The Valdai forest composition varied between closed spruce–birch forests and treeless tundra. Lakes persisted throughout the Valdai stage including the extremely dry last glacial maximum (LGM)-time when the Scandinavian Ice Sheet dammed the northbound rivers in the Vologda area.  相似文献   

Physiological status of whitefish (<Emphasis Type="Italic">Coregonus lavaretus pallasi</Emphasis>) prior to spawning in lakes of differing acidity     

Pekka?J.?VuorinenEmail author  Marja?Kein?nen  Antti?Lappalainen  Seppo?Peuranen  Martti?Rask 《Aquatic Sciences - Research Across Boundaries》2004,66(3):305-314

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Sedimentation and Iithostratigraphy of the North Sea Drift and Lowestoft Till Formations in the Coastal cliffs of northeast Norfolk,England     

Juha Pekka Lunkka 《第四纪科学杂志》1994,9(3):209-233

The most complete terrestrial sequence of Anglian (Elsterian) glacial sediments in western Europe was investigated in northeast Norfolk, England in order to reconstruct the evolution of the contemporary palaeoenvironments. Lithostratigraphically the glacial sediments in the northeast Norfolk coastal cliffs can be divided into the Northn Sea Drift and Lowestoft Till Formations. Three of the diamicton members of the North Sea Drift Formation (Happisburgh, Walcott and Cromer Diamictons) were deposited as lodgement and/or subglacial deformation till by grounded ice, but one, the Mundesley Diamicton, is waterlain and was deposited in an extensive glacial lake. Sands and fine sediments interbedded between the diamictons represent deltaic sands and glaciolacustrine sediments derived not solely from the melting ice in the north but also from extra-marginal rivers in the south. The Lowestoft Till Formation is not well preserved in the cliffs but includes lodgement till (Marly Drift till) and, most probably, associated meltwater deposits. Extensive glaciotectonism in the northern part of the area is shown to relate to oscillating ice that deposited the Cromer Diamicton and also partially to the ice sheet that deposited the Marly Drift till. It is suggested that during the Anglian Stage the present day northeast Norfolk coast was situated on the northwestern margin of an extensive glaciolacustrine basin. This basin was dammed by the Scandinavian ice sheet in the north and northeast. Because the grounding line of this ice sheet oscillated in space and time, part of the North Sea Drift diamictons were deposited directly by this ice. However, during ice retreat phases glaciolacustrine deposition comprised waterlain diamicton, sands and fines. When the Scandinavian ice sheet was situated in northernmost Norfolk, the British ice sheet (responsible for depositing the Marly Drift facies) entered the area from the west. This ice sheet partially deformed the North Sea Drift Formation sediments in the northern part of the area but not in the south, where the British ice sheet apparently terminated in water. The interplay of these two ice sheets on the northern and western margins of the glacial lake is thought to be the major determining factor for the accumulation of thick glacial deposits in this area during the Anglian glaciation.  相似文献   

Editorial: solar radiophysics—recent results on observations and theories     

Valery M. Nakariakov  ;Larisa K. Kashapova  ;Yi-Hua Yan 《中国天文和天体物理学报》2014,(7):I0001-I0006

Solar radiophysics is a rapidly developing branch of solar physics and plasma astrophysics. Solar radiophysics has the goal of analyzing observations of radio emissions from the Sun and understanding basic physical processes operating in quiet and active regions of the solar corona. In the near future, the commissioning of a new generation of solar radio observational facilities, which include the Chinese Spectral Radio Heliograph（CSRH） and the upgrade of the Siberian Solar Radio Telescope（SSRT）, and the beginning of solar observations with the Atacama Large Millimeter/submillimeter Array（ALMA）, is expected to bring us new breakthrough results of a transformative nature. The Marie-Curie International Research Staff Exchange（MC IRSES） “RadioSun” international network aims to create a solid foundation for the successful exploitation of upcoming solar radio observational facilities, as well as intensive use of the existing observational tools, advanced theoretical modeling of relevant physical processes and observables, and training a new generation of solar radio physicists. The RadioSun network links research teams from China,Czech Republic, Poland, Russia and the UK. This mini-volume presents research papers based on invited reviews and contributed talks at the 1st RadioSun workshop in China. These papers cover a broad range of research topics and include recent observational and theoretical advances in solar radiophysics, MHD seismology of the solar corona, physics of solar flares, generation of radio emission, numerical modeling of MHD and plasma physics processes, charged-particle acceleration and novel instrumentation.  相似文献   

Impact of peatland drainage and restoration on esker groundwater resources: modeling future scenarios for management   总被引：1，自引：0，他引：1  

Pekka M. Rossi  Pertti Ala-aho  John Doherty  Bjørn Kløve 《Hydrogeology Journal》2014,22(5):1131-1145

Esker aquifers are common groundwater bodies in Europe. Management of these aquifers should take account of the sustainability of groundwater-dependent ecosystems and land use in an integrated way. An unconfined esker aquifer in northern Finland was modelled with MODFLOW to determine how groundwater resources are impacted by the surrounding peatland drainage scheme and to simulate scenarios for possible drainage restoration. The impacts of groundwater abstraction and climate change were also simulated. A calibration-constrained Monte Carlo method was used to provide information on the uncertainties associated with model predictions. The results suggest that peatland drainage in the vicinity of eskers can have a significant role in lowering the water table, even though climate variability may mask these impacts. Drainage restoration by filling the ditches might have positive impacts on the aquifer water levels. Comparison of water-table changes caused by peatland drainage with the changes brought by water abstraction and climate variability helped to quantify impacts of different land-use scenarios and facilitated discussion with the local stakeholders. Based on this study, more attention should be devoted to peatland drainage schemes in integrated groundwater management of esker aquifers.  相似文献   

Biochemical biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)     

Hansson T  Schiedek D  Lehtonen KK  Vuorinen PJ  Liewenborg B  Noaksson E  Tjärnlund U  Hanson M  Balk L 《Marine pollution bulletin》2006,53(8-9):451-468

A battery of biochemical biomarkers and the SigmaPCB concentration in adult female perch (Perca fluviatilis) verified an aquatic pollution gradient with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included both an upstream gradient, 46 km westwards through Lake M?laren, and a downstream gradient, 84 km eastwards through the Stockholm archipelago. Besides the main gradient from Stockholm, there were strong indications of pollution coming from the Baltic Sea. The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch, characterised by increased specific EROD activity in the liver, increased liver EROD somatic index, decreased AChE activity in the muscle, increased amount of DNA adducts in the liver, and a high concentration of biliary 1-pyrenol. In addition, laboratory exposure to common EROD inducers elicited an abnormal response, suggestive of chronic intoxication.  相似文献