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301.
U. M. Leiko 《Kinematics and Physics of Celestial Bodies》2016,32(6):299-306
The results of an analysis of the north–south asymmetry in solar activity and solar magnetic fields are reported. The analysis is based on solar mean magnetic field and solar polar magnetic field time series, 1975–2015 (http://wso.stanford.edu), and the Greenwich sunspot data, 1875–2015 (http://solarscience.msfc.nasa.gov/greenwch.shtml). A long-term cycle (small-scale magnetic fields, toroidal component) of ~140 years is identified in the north–south asymmetry in solar activity by analyzing the cumulative sum of the time series for the north–south asymmetry in the area of sunspots. A comparative analysis of the variations in the cumulative sums of the time series composed of the daily values of the sun’s global magnetic field and in the asymmetry of the daily sunspot data over the time interval 1975–2015 shows that the photospheric large-scale magnetic fields may also have a similar long-term cycle. The variations in the asymmetry of large-scale and small-scale solar magnetic fields (sunspot area) are in sync until 2005.5 and in antiphase since then. 相似文献
302.
303.
The OSIRIS camera onboard Rosetta successfully acquired images of asteroid 2867 Steins through a variety of color filters during the flyby on 5 September 2008. The best images of this 5 km diameter asteroid have a resolution of 78 m per pixel. We process the images by deconvolving with the point spread function and enlarging through the Mitchell-Netravali filter. The enhanced set is analyzed by means of various techniques (PCA, band ratios, stereo anaglyphs) to study surface morphology and search for variegation. We identify a landslide, which supports a YORP origin for Steins’ unusual diamond shape. In addition, we find that the interior of one of two large craters on the south pole is bluer than the rest of the body. 相似文献
304.
Kinder A Sierts-Herrmann A Biselli S Heinzel N Hühnerfuss H Kammann U Reineke N Theobald N Steinhart H 《Marine environmental research》2007,63(5):506-515
Heat shock proteins 70 (hsp70) are known to be induced by a great variety of chemical stressors. The effects of different environmental contaminants, which were identified in sediments of the North Sea and the Baltic Sea as main contaminants or as contaminants of special toxicological interest, on the extent of expression of hsp70 in a permanent cell line Epithelioma papulosum cyprini (EPC) were investigated. Concentrations of the single contaminants leading to elevated hsp70 levels were compared to the respective concentrations of these contaminants encountered in the sediment extracts thus allowing an assessment of their contribution to the toxicity of these sediments. Analysis of hsp70 was performed using western blotting techniques with subsequent comparative quantification by densitometry. Eleven of thirteen contaminants have shown a dose-dependent increase in hsp70 levels. An expression of hsp70 was observed in most cases between 0.1 and 10 microg/mL test solution. Some of the investigated stressors led to extremely high hsp70 contents even at low concentrations. However, in most cases contaminant concentrations in sediments were too low to cause an effect. For this reason, effects of the tested sediments are attributed to other contaminants or rather to mixtures of stressors. 相似文献
305.
306.
In Jabalpur area about 18 m to 45 m thick Lameta Formation is stratigraphically divisible into five lithounits namely, Green
Sandstone, Lower Limestone, Mottled Nodular Beds, Upper Limestone and Upper Sandstone. Having differentiated lithofacies constitution
and here grouped as facies associations, these units are intensively burrowed and sparingly fossiliferous. Ichnogenera including
Arenicolites, Calycraterion, Fucusopsis, Laevicyclus, Macanopsis, Ophiomorpha, Paleomeandron, Rhizocorallium, Stipsellus,
Thalassinoides and Zoophycos are recovered from the Lower Limestone, Mottled Nodular Beds and Upper Limestone associations of the Lameta Formation of
Jabalpur area.Among these, Arenicolites, Calycraterion, Laevicyclus, Ophiomorpha, Rhizocorallium, Stipsellus and Thalassinoides belong to mixed Skolithos and Cruziana ichnofacies and indicate sandy backshore to sublittoral condition of deposition. Additionally rhyzocretes, some times chertified,
are also present in different parts of the Lameta Formation. Ichnofacies assemblage supported by sedimentological information
suggests that the Lameta Formation of Jabalpur area was deposited in coastal marine settings where sediments were subaerially
exposed intermittently. 相似文献
307.
A 132 kVA electrical transmission line has been proposed to connect the towns of Eket and Ikot Abasi in the eastern Niger
delta in Nigeria. A geotechnical and hydrological study was performed to geotechnically characterize the route alignment and
to provide data for design of the foundations for the transmission towers. In this paper, we introduce the study location
and its geological, topographical and physiological characteristics, present the hydrological and geotechnical investigations
and their results, and make recomendations for the design of the transmission tower foundations. Hydrological inspection of
the power line alignment revealed that the route is traversed by numerous tributaries of the Qua-Iboe and Imo Rivers, the
two major rivers that control the drainage of the study area. In-situ geotechnical tests consisted of cone penetration tests
(CPTs), vane shear tests, test pit sampling (0–2.0 m depth) and lithologic boreholes (20 and 50 m deep). Laboratory tests
included grain size analysis, pH determination and Atterberg Limits. Based on the CPT log pattern, no of stratum, and refusal
depths, the soils along the transmission alignment were classified into twelve structural domains having common geotechnical
properties. Because of the elevated water levels, and the nature of the soils, deep pile foundations were recommended for
the towers. Software from the Louisiana Transportation Research Center, was employed to estimate skin friction, end bearing,
and ultimate bearing capacities for assumed 225 mm square shaped reinforced concrete pile in each of the different zones of
the alignment. 相似文献
308.
309.
Thermal and exhumation history of the central Rwenzori Mountains, Western Rift of the East African Rift System, Uganda 总被引:2,自引:1,他引:1
F. U. Bauer U. A. Glasmacher U. Ring A. Schumann B. Nagudi 《International Journal of Earth Sciences》2010,99(7):1575-1597
The Rwenzori Mountains (Mtns) in west Uganda are the highest rift mountains on Earth and rise to more than 5,000 m. We apply
low-temperature thermochronology (apatite fission-track (AFT) and apatite (U–Th–Sm)/He (AHe) analysis) for tracking the cooling
history of the Rwenzori Mtns. Samples from the central and northern Rwenzoris reveal AFT ages between 195.0 (±8.4) Ma and
85.3 (±5.3) Ma, and AHe ages between 210.0 (±6.0) Ma to 24.9 (±0.5) Ma. Modelled time–temperature paths reflect a protracted
cooling history with accelerated cooling in Permo-Triassic and Jurassic times, followed by a long period of constant and slow
cooling, than succeeded by a renewed accelerated cooling in the Neogene. During the last 10 Ma, differentiated erosion and
surface uplift affected the Rwenzori Mtns, with more pronounced uplift along the western flank. The final rock uplift of the
Rwenzori Mtns that partly led to the formation of the recent topography must have been fast and in the near past (Pliocene
to Pleistocene). Erosion could not compensate for the latest rock uplift, resulting in Oligocene to Miocene AHe ages. 相似文献
310.
Zinc availability in relation to selected soil properties in a crude oil polluted eutric tropofluvent 总被引:2,自引:2,他引:0
M. C. Chukwuma E. T. Eshett E. U. Onweremadu Ph.D. M. A. Okon 《International Journal of Environmental Science and Technology》2010,7(2):261-270
The study investigated zinc availability in relation to selected soil properties in a crude-oil-polluted Eutric Tropofluvent in Egbema, Southeastern Nigeria. For this purpose, three treatments have been applied: unpolluted soil, polluted without vegetation and polluted with vegetation with five replicates arranged in a randomized complete block design. Guided by transect sampling technique, soil sampling was carried out in June 2008. Soil samples were collected from the three different land units using soil auger at a depth of 0–20 cm. Standard laboratory procedures were adopted in analysing the soils. Soil generated data were subjected to analysis of variance and correlation analysis. Results showed highly significant variation (p = 0.01) in bulk density, porosity, silt: clay ratio, pH, effective cation exchange capacity, percent base saturation, total nitrogen, organic matter, available phosphorus, calcium: magnesium ratio and zinc. It was found that zinc was higher in crude oil polluted soils than in non-polluted soil and it was below critical limits. Zinc availability in relation to selected soil properties in the crude oil polluted soils indicated that clay and organic matter did not affect zinc availability, while pH and effective cation exchange capacity did. A study on zinc dynamics in crude-oil-polluted soils will certainly provide further information on the management of crude-oil-polluted soils since it is one of the key micronutrient for crop productivity. 相似文献