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31.
This article examines the implementation and impacts of a program intended to improve research-led teaching in schools. Little consideration is given to the role of research-led teaching in schools; the argument is that this is a consequence of fractures between schools and universities. A program was developed to bring contemporary geographical research of university scholars into schools. Examining this program, the finding is that being exposed to research: improves access to up-to-date knowledge; heightens student enthusiasm; and informs choices students make about their learning. This article calls for bridges to be built between universities and schools upon the nexus of teaching and research. 相似文献
32.
Apolinarska Karina Pleskot Krzysztof Pełechata Aleksandra Migdałek Michał Pełechaty Mariusz 《Journal of Paleolimnology》2021,66(1):41-53
Journal of Paleolimnology - We conducted year-round, monthly monitoring of the stable isotope composition of DIC and water in hypereutrophic Lake Kierskie, western Poland, along with isotope... 相似文献
33.
Krzysztof Kolon Aleksandra Samecka-Cymerman Alexander J. Kempers Lucyna Mróz 《Journal of Atmospheric Chemistry》2010,66(3):157-166
Concentrations of the elements Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn were measured in the moss Pleurozium schreberi from the Tatra National Park, one of the most protected regions in Poland. The moss samples were collected at different elevations
between 860 and 2220 m a.s.l. P. schreberi was used as bioindicator for long range transported atmospheric pollution investigating the hypothesis that elevation influences
the concentrations of elements in this moss. Principal component and classification analysis (PCCA) distinguished between
mosses from the highest and the lowest elevations and mosses from West/East oriented valleys. P. schreberi from the highest elevations contained the highest concentrations of Cd, Cu, Cr, Fe, Mn, Pb, V and Zn. P. schreberi from the lowest elevation contained the highest concentration of K. P. schreberi from West/East oriented valleys contained the highest concentrations of Ni and Co. P. schreberi from the Tatra National Park, one of the most protected areas in Poland, receives metals originating from long distance aerial
transport. 相似文献
34.
Marek Biesiada Aleksandra Piórkowska 《Monthly notices of the Royal Astronomical Society》2009,396(2):946-950
It is generally expected that quantum gravity theory should yield the model of a space–time foam at short distances leading to Lorentz-invariance violation (LIV) manifested e.g. by energy-dependent modification of the standard relativistic dispersion relation. One direction of research, pursued intensively, is to measure the energy-dependent time-of-arrival delays in photons emitted by astrophysical sources located at cosmological distances. This is tempered, however, by our ignorance of intrinsic emission delays in different energy channels.
In this paper we discuss a test based on gravitational lensing. Monitoring time delays between images obtained in different energy channels, for example optical (low-energy) and TeV photons, may reveal extra delays due to the distorted dispersion relation typical in LIV theories, a test that is free from the systematics inherent in other settings. 相似文献
In this paper we discuss a test based on gravitational lensing. Monitoring time delays between images obtained in different energy channels, for example optical (low-energy) and TeV photons, may reveal extra delays due to the distorted dispersion relation typical in LIV theories, a test that is free from the systematics inherent in other settings. 相似文献
35.
Aleksandra Šajnović Ksenija Stojanović Branimir Jovančićević Anatoly Golovko 《Environmental Geology》2009,56(8):1629-1641
Sediments from the Valjevo-Mionica Basin of Neogene age were investigated in this study using different geochemical methods.
The results of the inorganic part analyses suggest that during genesis of the sediments, the contents of Na2O, B and As changed the most, which indicates that genesis of the investigated sediments was followed by climate changes and
volcanic activity. The quantity of other macro- and microelements did not vary significantly. Investigations of the organic
substance showed that it is native organic matter, which has been preserved to a significant extent, formed predominantly
of algal precursor organisms, which provided good quality, deposited under reducing conditions and that it is at a low maturity
level. As it has been established that genesis of the investigated sediments was mostly affected by an arid climate with more
intensive salinity, the aim of this study, was also to identify the processes which were the most affected by the change in
salinity, as well as biomarkers which are the most sensitive to this change. The results led to the conclusion that the salinity
increase in the depositional environment had a primary effect on the preservation of the organic substance and the formation
of the mineral searlesite. In addition, it was noticed that besides the Sq/nC26 ratio, the parameters nC17/nC27, CPI and Ph/nC18, are also significantly sensitive to salinity change in a depositional environment in case of immature organic substance
deposited under reducing conditions. 相似文献
36.
Aleksandra Smyrak-Sikora Per Terje Osmundsen Alvar Braathen Kei Ogata Ingrid Anell Mark J. Mulrooney Valentin Zuchuat 《Basin Research》2020,32(5):949-978
World-class examples of fault-controlled growth basins with associated syn-kinematic sedimentary fill are developed in Upper Triassic prodelta to delta-front deposits exposed at Kvalpynten, SW Edgeøya in East Svalbard. They are interpreted to have interacted with north-westerly progradation of a regional delta system. The syn-kinematic successions consist of 4 to 5 coarsening-upward units spanning from offshore mudstones to subtidal heterolithic bars and compound tidal dunes, which were blanketed by regional, post-kinematic sandstone sheets deposited as laterally continuous, subaqueous tidal dune fields. The rate of growth faulting is reflected in the distribution of accommodation, which governs sedimentary architecture and stacking patterns within the coarsening-upward units. Fully compartmentalized basins (12, 200–800 m wide and c. 150 m high grabens and half grabens) are characterized by syn-kinematic sedimentary infill. These grabens and half-grabens are separated by 60–150 m high horsts composed of pro-delta to distal delta-front mudstones. Grabens host tabular tidal dunes (sandwaves), whereas half-grabens bound by listric faults (mainly south-dipping) consist of wedge-shaped, rotated strata with erosive boundaries proximal to the uplifted fault block crests. Heterolithic tidal bars (sand ridges) occur in narrow half-grabens, showing migration oblique to the faults, up the dipslope. Structureless sandstone wedges and localized subaqueous slumps that formed in response to collapse of the block crests were only documented in half-grabens. Late-kinematic deposition during the final stages of faulting occurred in partly compartmentalized basins, filled with variably thick sets of continuous sandstone belts (compound tidal dunes). 相似文献
37.
Sanja Mrki?Ksenija Stojanovi? Aleksandar Kosti?Hans Peter Nytoft Aleksandra Šajnovi? 《Organic Geochemistry》2011,42(6):655-677
The origin, depositional environment and maturity of petroleum source rocks were determined via conventional whole rock and biomarker analysis of samples from wells in the Banat Depression, where the most important Serbian oil and gas fields are located. The organic matter (OM) in organic-rich upper Tertiary siltstones and marls consists predominantly of Type II kerogen. Numerous biomarker parameters indicated mixed algal-terrestrial OM, related to a brackish or freshwater environment, whose salinity decreased from Middle to Upper Miocene. The OM was deposited under variable redox conditions, reducing to sub-oxic.The wells in the Banat Depression experienced variable high rates of rapid heating, providing an opportunity for examining the applicability of different thermal indicators in a hyperthermal basin. Rock-Eval and numerous biomarker parameters indicate that the main stage of oil generation begins at ca.130 °C and vitrinite reflectance (Rc) ca. 0.63% and reaches a maximum at ca.145-150 °C and Rc ca. 0.72-0.75%, while the late stage of oil generation starts at ca.155 °C and ca. Rc 0.78%, which corresponds, depending on geothermal gradient, to relative depths of 2100-2300 m, 2600-2900 m and 3050-3100 m, respectively. The naphthalene and phenanthrene maturity parameters proved to be less applicable than the biomarker ratios, particularly in the early to moderate maturation range. The newly proposed parameter C(14a)-homo-26-nor-17α(H)-hopane/C30hopane (C30HH/C30H) proved applicable to a wide range of maturity. 相似文献
38.
Karem Azmy Uwe Brand Paul Sylvester Sara A. Gleeson Alan Logan Maria Aleksandra Bitner 《Chemical Geology》2011,280(1-2):180-190
The ΣREE and shale-normalized (PAAS) REESN values of modern brachiopods (biogenic low-Mg calcite: bLMC) represented by several species from high- to low latitudes, from shallow- to deep waters and from warm- and cold-water environments, define three distinct average ‘seawater’ trends. The warm- and cold-water brachiopods define two indistinguishable (p < 0.050) groups that mimic open-ocean seawater REE chemistry, exhibiting the typical LREE enrichment with a slightly positive to negative Ce anomaly followed by an otherwise invariant series. Other recent brachiopods from an essentially siliciclastic seabed environment are distinct in both ΣREE and REESN trends from the previous two populations, showing a slight enrichment in the MREEs and an increasing trend in the HREEs. Other groups of modern brachiopods are characterized by elevated REESN trends relative to the ‘normal’ groups as well as by complexity of the series trends. The most characteristic feature is the decrease in the HREEs in these brachiopods from areas of unusual productivity (i.e., such as upwelling currents, fluvial input and aerosol dust deposition). Preserved brachiopods from the Eocene and Silurian exhibit REESN trends and Ce anomalies similar to that of the ‘open-ocean’ modern brachiopods, although, their enriched ΣREE concentrations suggest precipitation of bLMC influenced by extrinsic environmental conditions.Preservation of the bLMC was tested by comparing the ΣREE and REESN trends of preserved Eocene brachiopods to those of Oligocene brachiopods that were altered in an open diagenetic system in the presence of phreatic meteoric-water. The altered bLMC is enriched by approximately one order of magnitude in both ΣREE and REESN trends relative to that in bLMC of their preserved counterparts. Similarly, the ΣREE and REESN of preserved Silurian brachiopod bLMC were compared to those of their enclosing altered lime mudstone, which exhibits features of partly closed system, phreatic meteoric-water diagenesis. Despite these differences in the diagenetic alteration systems and processes, the ΣREEs and REESN trends of the bLMC of altered brachiopods and of originally mixed mineralogy lime mudstones (now diagenetic low-Mg calcite) are enriched by about one order of magnitude relative to those observed in the coeval and preserved bLMC.In contrast to the changes in ΣREE and REESN of carbonates exposed to phreatic meteoric-water diagenesis, are the REE compositions of late burial calcite cements precipitated in diagenetically open systems from burial fluids. The ΣREE and REESN trends of the burial cements mimic those of their host lime mudstone, with all showing slight LREE enrichment and slight HREE depletion, exhibiting a ‘chevron’ pattern of the REESN trends. The overall enrichment or depletion of the cement REESN trends relative to that of their respective host rock material reflects not only the openness of the diagenetic system, but also strong differences in the elemental and REE compositions of the burial fluids. Evaluation of the (Ce/Ce*)SN and La = (Pr/Pr*)SN anomalies suggests precipitation of the burial calcite cements essentially in equilibrium with their source fluids. 相似文献
39.
In the Variscan Western Tatra granites hybridization phenomena such as mixing and mingling can be observed at the contact of mafic precursors of dioritic composition and more felsic granitic host rocks. The textural evidence of hybridization include: plagioclase?CK-feldspar?Csphene ocelli, hornblende- and biotite-rimmed quartz ocelli, plagioclase with Ca-rich spike zonation, inversely zoned K-feldspar crystals, mafic clots, poikilitic plagioclase and quartz crystals, mixed apatite morphologies, zoned K-feldspar phenocrysts. The apparent pressure range of the magma hybridization event was calculated at 6.1?kbar to 4.6?kbar, while the temperature, calculated by independent methods, is in the range of 810°C?770°C. U-Pb age data of the hybrid rocks were obtained by in-situ LA-MC-ICP-MS analysis of zircon. The oscillatory zoned zircon crystals yield a concordia age of 368?±?8?Ma (MSWD?=?1.1), interpreted as the age of magma hybridization and timing of formation of the magmatic precursors. It is the oldest Variscan magmatic event in that part of the Tatra Mountains. 相似文献
40.
Glen M. MacDonald Andrei A. Velichko Constantine V. Kremenetski Olga K. Borisova Aleksandra A. Goleva Andrei A. Andreev Les C. Cwynar Richard T. Riding Steven L. Forman Tom W. D. Edwards Ramon Aravena Dan Hammarlund Julian M. Szeicz Valery N. Gattaulin 《Quaternary Research》2000,53(3):302
Radiocarbon-dated macrofossils are used to document Holocene treeline history across northern Russia (including Siberia). Boreal forest development in this region commenced by 10,000 yr B.P. Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia. Treeline advance on the Kola Peninsula, however, appears to have occurred later than in other regions. During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern. The development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions, including heightened summer insolation, the demise of Eurasian ice sheets, reduced sea-ice cover, greater continentality with eustatically lower sea level, and extreme Arctic penetration of warm North Atlantic waters. The late Holocene retreat of Eurasian treeline coincides with declining summer insolation, cooling arctic waters, and neoglaciation. 相似文献