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31.
Attila Mészáros 《Astrophysics and Space Science》1985,111(2):399-405
Graviton may, in principle, have a small non-zero mass. In this paper the relevant theory of the massive graviton with six polarisations is developed. The drastic impact of a non-zero mass of the graviton on cosmology is also illustrated. 相似文献
32.
Gabriella Sch?ll-Barna Attila Demény Gábor Serlegi Szilvia Fábián Pál Sümegi István Fórizs Bernadett Bajnóczi 《Journal of Paleolimnology》2012,47(1):87-100
Geochemical records of bivalve shells have been increasingly studied in the last decade to obtain information on climate conditions.
In this paper we present stable isotope compositions of living and prehistoric shells of freshwater mussels (Unionidae) and
their relationships with climate conditions in a shallow lake environment of Lake Balaton, West-Central Hungary. Physical
conditions and stable oxygen isotope compositions of lake water samples were monitored where living bivalves were collected.
Comparisons between seasonal variations in ambient temperature, water composition and within-shell isotopic variations indicate
that the shells of Unio pictorum do reflect local changes at high resolution and thus can be used to study past conditions. Additionally, shells covering
the last two decades were gathered at several locations along the lake in order to determine spatial and temporal variations
in the shells’ isotopic compositions as a function of weather conditions. As an application, prehistoric shells collected
in archaeological excavations were analysed in order to study past environmental variations. Climate variations during the
Late Copper Age (5460–4870 cal. yr BP) have been assumed on the basis of geomorphological and archaeozoological observations
at the site Balatonkeresztúr-Réti-dűlő (south of Lake Balaton), that suggested increasing humidity as a cause of changes in
settlement location and domestic livestock husbandry. Stable carbon and oxygen isotope compositions of prehistoric bivalve
shells were analyzed from excavations representing five archaeological subphases (Boleráz subphase, 5460–5310 cal. yr BP;
two transitional subphases around 5310 cal. yr BP; Early Classic subphase, 5310–5060 cal. yr BP; Late Classic subphase, 5040–4870 cal.
yr BP). The analyses revealed significant negative C and O isotope shifts in the transitional subphases relative to the earlier
and later subphases. The isotopic variations indicate that the local climate became relatively wet and possibly cold around
5310 cal. yr BP, then it returned to drier (and likely warmer) conditions during the Classic subphases. This interpretation
is in agreement with previous studies on climate changes related to the “5.3 ky event” in the European continental area and
the North Atlantic Region, indicating an Atlantic influence in the Carpathian Basin. 相似文献
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36.
Tomáš Navrátil James B. Shanley Jan Rohovec Irena Dobešová Šárka Matoušková Michal Roll Tereza Nováková Filip Oulehle 《水文研究》2021,35(6):e14255
From 2011 to 2019, mercury (Hg) stores and fluxes were studied in the small forested catchment Lesní potok (LES) in the central Czech Republic using the watershed mass balance approach together with internal measurements. Mean input fluxes of Hg via open bulk deposition, beech throughfall and spruce throughfall during the periodwere 2.9, 3.9 and 7.6 μg m−2 year−1, respectively. These values were considerably lower than corresponding deposition Hg fluxes reported in the early years of the 21st century from catchments in Germany. Current bulk precipitation inputs at unimpacted Czech mountainous sites were lower than those in Germany. The largest Hg inputs to the catchment were via litterfall, averaging 22.6 and 17.8 μg m−2 year−1 for beech and spruce stands. The average Hg input, based on the sum of mean litterfall and throughfall deposition, was 23.0 μg m−2 year−1, compared to the estimated Hg output in runoff of 0.5 μg m−2 year−1, which is low compared to other reported values. Thus, only ~2% of Hg input is exported in stream runoff. Stream water Hg was only weakly related to dissolved organic carbon (DOC) but both concentrations were positively correlated with water temperature. The estimated total soil Hg pool averaged 47.5 mg m−2, only 4% of which was in the O-horizon. Thus Hg in the O-horizon pool represents 72 years of deposition at the current input flux and 3800 years of export at the current runoff flux. Age-dating by 14C suggested that organic soil contains Hg from recent deposition, while mineral soil at 40–80 cm depth contained 4400-year old carbon, suggesting the soil had accumulated atmospheric Hg inputs through millennia to reach the highest soil Hg pool of the soil profile. These findings suggest that industrial era intensification of the Hg cycle is superimposed on a slower-paced Hg cycle during most of the Holocene. 相似文献
37.
Arantxa Luzón Angel González Arsenio Muñoz Belén Sánchez-Valverde 《Journal of Paleolimnology》2002,28(4):441-456
The lacustrine facies from two sections (Candasnos and Fraga) ofthe Oligocene-Miocene Torrente de Cinca lithostratigraphic Unit in thecentral part of the Ebro Basin (Spain) have been analysed to determine theinfluence of orbital parameters in lacustrine sedimentation. The unit ispredominantly composed of limestones and marls, and represents a shallowlacustrine freshwater system. The sedimentological features of the faciesstudied demonstrate that the lower part of the Candasnos section representsoffshore lacustrine subenvironments whereas the upper part, and the whole ofthe Fraga section, characterise marginal lacustrine areas. Series of stratalthickness variations of limestone, marl, and limestone/marl couplets fromboth sections have been analysed using spectral analysis. This shows thatinformation corresponding to periodic cycles only appears in the offshorefacies, that is to say, in the lower part of Candasnos section, and disappearsin the marginal facies where non-periodic cycles exist. Furthermore, thespectral analysis of the offshore facies highlights the existence of a peak inthe power spectrum with a period of around 7 (6.8 to 7.8) that can berecognised in the field as shallowing-upward lacustrine sequences.Magnetostratigraphic data from the Candasnos section allow us to establish atime span of 2,808 years for the limestone/marl couplet from the lower partof this section, and between 19,000 and 22,000 years for the periodic cycleidentified, thus representing the climatic precession cycle. Shallowingsequences from marginal areas do not correspond with any periodiccycle. 相似文献
38.
The composition of the impact plasma produced by fast dust particles (v > 1 km/sec) hitting an Au or W target was measured both with a model of the HELIOS micrometeoroid experiment (low electric field at the target) and a high field detector. The plasma composition and the total plasma charge depend strongly on the impact velocity and the electric field strength at the target. Spectra of 9 different projectile-target combinations were analysed. Two types of spectra could be observed, depending on the projectile material. (1) Spectra of metals and hard dielectrics (Mohs' hardness ? 5). Particle constituents of low ionisation energy (e · u ? 7eV, e.g. Na, K, Al) dominate the spectra of these materials at impact velocities below 10 km/sec. At higher speed the relative intensities change and new ions with higher ionisation energies appear. (2) Spectra of soft dielectrics (Mohs' hardness < 3). Below 9 km/sec these materials produced less total charge than did the others. The highest masses were detected at 74 amu. The relative abundance of ions with low ionization energies such as Li, Na, K, etc. is comparatively small. Negative ions were also observed in the impact plasma. Their total number was found to be approximately 3–6% of that of the positive ions at 6 km/sec particle speed. 相似文献
39.
The accumulation of sediment in river channels is a phenomenon that is not only influenced by the channel morphology, but also by the physical and geographical characteristics and the endogenous and exogenous processes taking place in the catchment. This paper presents an analysis of the impact the changes in lithological conditions have on the morphological and morphometric parameters of the Udava River channel and their relation to the channel accumulation forms representative of the river’s longitudinal profile as well as of its planform. Results document when accumulation forms occur and what is their spatial distribution within the longitudinal and cross-sectional river profiles. More resistant structures created sections with a lower degree of sedimentation, while in depression segments the degree of sedimentation was higher. With the increase in longitudinal slope, the impact of channel width on the average channel bar size increased. Also a difference in the accumulation was observed between the left and right bank which could be possibly explained by the impact of Coriolis force. 相似文献
40.
The interaction of carbon dioxide and amorphous water ice at 95 K is studied using transmission infrared spectroscopy. Samples are prepared in two ways: co-deposition of the gases admitted simultaneously or sequential deposition, in which amorphous water ice (ASW) is grown first and CO2 vapor is added subsequently. In either case, a fraction of the CO2 molecules is found to interact with water in a way that gives rise to shifts and splittings in the infrared bands with respect to those of a pure CO2 solid. In co-deposition experiments, a larger amount of carbon dioxide is trapped within the amorphous water than in sequential deposition samples, where a substantial proportion of molecules appears to be trapped in macropores of the ASW. The specific surface area of sequential samples is evaluated and compared to previous literature results. When the sequential samples are heated to 140 K, beyond the onset temperature at which water ice undergoes a phase transition, the CO2 molecules at the pores relocate inside the bulk in a structure similar to that found in co-deposited samples, as deduced by changes in the shape of the CO2 infrared bands. 相似文献