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91.
92.
The Romanian earthquake of August 30, 1986 is the second largest intermediate depth event in this area since the worldwide deployment of digital instrumentation, and the first one since the installation of GEOSCOPE network. It offers the unique opportunity to document this well-known but poorly understood zone of deep continental seismicity using high quality teleseismic data in different frequency bands. The source is well constrained both from very-long period surface wave data observed on GEOSCOPE stations and, independently, from body wave modelling at various worldwide stations. The depth obtained is approximately 140 kilometers, the seismic moment, 0.8 1027 dyne-cm and the mechanism from both data sets is very similar to that of the previous 1940 and 1977 Vancrea events, indicating that these events, although having occurred at noticeably different depths, are expressions of the same tectonic process. However, from the detailed study of the source using broadband data, it can be inferred that the source presents much less complexity than the 1977 event. 相似文献
93.
Hydrogeological Decision Analysis: 1. A Framework 总被引:6,自引:0,他引:6
R. Allan Freeze Joel Massmann Leslie Smith Tony Sperling Bruce James 《Ground water》1990,28(5):738-766
94.
The characterization of the static stability of the troposphere over the western maritime Arctic remains limited in spite of its significance to both atmospheric thermodynamics and dynamics. Field observations of microwave radiometric temperature profiles from the International Polar Year, Circumpolar Flaw Lead System Study (late November 2007 to mid-July 2008) and the ArcticNet field campaign (mid-July to early November 2009) provided a unique opportunity to characterize the static stability of the troposphere over the southeastern Beaufort Sea–Amundsen Gulf region. Notably, the monthly median atmospheric boundary layer (<2000?m) static stability profile for April and the profile for May clearly revealed an inversion elevated above a thermal internal boundary layer, whereas the median summer static stability profiles had very strong surface-based inversions. These profiles have been linked to the seasonal evolution of sea-ice cover in Amundsen Gulf. The monthly static stability profiles for the free atmosphere (2000–10,000?m) revealed an annual cycle. The average static stability of the lower troposphere (2000–5000?m) had a minimum of 3.3?±?0.5?K?km?1 in July and a maximum of 4.5?±?0.5?K?km?1 in January and February. In the upper troposphere (>5000–8000?m), the average static stability had a minimum of 2.9?±?0.6?K?km?1 in June and August and a maximum of 5.3?±?0.8?K?km?1 in January. The monthly median heights of the tropopause also had an annual cycle. The maximum of 9750?m occurred in June, July, and August. The minimum tropopause height of 8000?m occurred in December, January, and March. The seasonal cycles of static stability in the free atmosphere and the seasonal cycle in the height of the tropopause can be attributed to regional as well as synoptic-scale forcing. This analysis will contribute to the understanding of the thermodynamics and dynamics of a data-sparse region of the Arctic by providing a “snapshot” of the state of the atmosphere through a composite annual cycle. 相似文献
95.
96.
Uptake of inorganic carbon and ammonium by the plankton community of three North Carolina estuaries was measured using 14C and 15N isotope methods. At 0% light, C appeared to be lost via respiration, and at increasing light levels uptake of inorganic carbon increased linearly, saturated (mean Ik = 358±30 μEin m−2 s−1), and frequently showed inhibition at the highest light intensities. At 0% light NH4+ uptake was significantly greater than zero and was frequently equivalent to uptake in the light (light independent); at increasing light levels NH4+ uptake saturated (mean Ik = 172±44 μEin m−2 s−1) and frequently indicated strong inhibition. Light-saturated uptake rates of inorganic carbon and NH4+ were a function of chlorophyll a (r2 = 0·7−0·9); average assimilation numbers were 625 nmol CO2 (μg chl. a)−1 h−1 and 12·9 nmol NH4+ (μg chl. a)−1 h−1 and were positively correlated with temperature (r2 = 0·3−0·7). The ratio of dark to light-saturated NH4+ uptake tended to be near 1·0 for large algal populations at low NH4+ concentrations, indicating near light independence of uptake; whereas the ratio was lower for the opposite conditions. These data are interpreted as indicative of nitrogen stress, and it is suggested that uptake of NH4+ deep in the euphotic zone and at night are mechanisms for balancing the C:N of cellular pools. A 24-h study using summed short-term incubations confirmed this; the cumulative C:N of CO2 and NH4+ uptake during the daylight period was 10–20, whereas over the 24-h period the ratio was 6 due to dark NH4+ uptake. Annual carbon and nitrogen primary productivity were respectively estimated as 24 and 4·0 mol m−2 year−1 for the South River estuary, 42 and 7·3 mol m−2 year−1 for the Neuse River estuary, and 9·6 and 1·6 mol m−2 year−1 for the Newport River estuary. 相似文献
97.
GSTA is a major glutathione S-transferase gene responsible for 4-hydroxynonenal conjugation in largemouth bass liver 总被引:2,自引:0,他引:2
We have previously shown that largemouth bass (Micropterus salmoides) has a remarkable ability to conjugate 4-hydroxy-2-nonenal (4HNE), a mutagenic and cytotoxic alpha,beta-unsaturated aldehyde produced during the peroxidation of lipids. In addition, we have isolated a glutathione S-transferase cDNA (bass GSTA) that encodes a recombinant protein which is highly active in 4HNE conjugation and structurally similar to plaice (Pleuronectes platessa) GSTA. In the present study, HPLC-GST subunit analysis revealed the presence of at least two major GST isoforms in bass liver, with one peak constituting 80% of the total bass liver GST protein. Liquid chromatography mass spectrometry (LC-MS) and electrospray ionization analysis of the major bass GST subunit yielded a molecular weight of 26,396 kDa. Endo-proteinase Lys-C digestion and Edman degradation protein sequencing of this GST peak demonstrated that this protein was encoded by bass GSTA. Analysis of genomic DNA fragments isolated by nested PCR indicated the presence of a GST gene cluster in bass liver that contained GSTA, and was similar to a GST gene cluster characterized by Leaver et al., in plaice. Collectively, our data indicates the presence of a major GST in bass liver involved in the protection against oxidative stress. This GST is part of a gene cluster that may be conserved in certain freshwater and marine fish. 相似文献
98.
99.
Tony Waltham 《Geology Today》2017,33(1):32-40
A dry waterfall that recently came to life, a landform that is not karstic in the middle of a great karst terrain, underground drainage that is not as simple as it seems, and on‐going debate about how it was formed: Malham Cove is more than just a spectacular sight. 相似文献
100.
Tony Waltham 《Geology Today》2007,23(3):101-107
Switzerland's Lötschberg tunnels present a long story of both failure and success. Tunnelling that began 100 years ago ended in a massive disaster–which is a classic of engineering geology–but subsequent works were very much more successful. 相似文献