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711.
Changes in tropopause height for the Eurasian region determined from CARDS radiosonde data 总被引:2,自引:0,他引:2
Previous studies have identified the tropopause height (TH) as a promising fingerprint of climatic change. In the present paper, we report variations in TH for the Eurasian region over the period 1973–1998 and analyse the influence of the Northern Annular Mode (NAM) on these variations. As previous studies indicate that the greatest increases in TH occur in the extratropics, we focused our attention on this area. We applied a set of homogenization procedures to radiosonde data and considered three different scenarios that take into account change points and the main volcanic eruptions over the study period. Our results demonstrate that the number of stations with positive TH trends is very sensitive to the quality of data and the methods used to remove inhomogeneities. Consequently, when change points were included in the analysis, the number of stations with positive trends decreased markedly. Furthermore, stratospheric NAM appears to control TH in stations located at latitudes higher than 55°N.Electronic supplementary materials Supplementary material is available for this article at and is accessible to authorized users. 相似文献
712.
We sampled residues from high-order and low-order blow-in-place detonations of mortars and projectiles filled with Composition B (Comp B), a TNT and RDX mixture. Our goals were to (1) characterize the types of explosive particles, (2) estimate the explosive 'footprint' for different munitions, and (3) estimate the mass of Comp B remaining after each detonation. The aerial deposition of Comp B particles helps estimate how large of an area is contaminated by a low-order detonation and how best to sample residue resulting from different rounds. We found that the high-order detonations deposited microgram to milligram quantities whereas the low-order detonations deposited gram quantities of Comp B. For the high-order detonations the concentration of Comp B in the residue decreased as a function of distance from the blast. The low-order tests scattered centimeter-sized chunks and millimeter-sized or smaller particles of Comp B. The chunks were randomly scattered whereas the number of millimeter-sized particles decreased with distance from the detonation. For both high- and low-order detonations we found that the smaller munitions deposited less Comp B than the larger munitions and deposited it closer to the detonation point. 相似文献
713.
Successful invaders often become established in new ranges by outcompeting native species. The “evolution of increased competitive ability” hypothesis predicts that invasive species are subjected to less predation and parasitization than sympatric native species, and thus can allocate resources from defence and immunity to growth and fecundity, thereby achieving higher fitness. In this study, we examined whether American invasive Polistes dominula paper wasps have reduced immunocompetence. To explore this scenario, we tested their susceptibility towards parasites and pathogens at both the individual (immune defence) and colony levels, i.e. hygienic behaviour (removal of diseased individuals by nestmates). First, we examined the response to the specific coevolved parasite Xenos vesparum (lost after invasion) in terms of individual host susceptibility and hygienic behaviour. Second, we explored the response against general pathogens by quantifying the bacterial clearance in individual wasps after a challenge with Escherichia coli and hygienic behaviour after a challenge with the fungus Beauveria bassiana. Our results show that American invasive P. dominula have a higher response against X. vesparum at the colony level, but at the individual level their susceptibility is not significantly different from conspecifics of the native range. On the other hand, invasive P. dominula display lower response after a challenge with general pathogens at both the individual and colony levels. While supporting the hypothesis of a reduction of immunocompetence towards general pathogens in invasive species, these findings also suggest that the response against coevolved parasites might follow different evolutionary pathways which are not always easily predictable. 相似文献
714.
Aline Brum Geovana Dotta Katina Roumbedakis Eduardo L. T. Gonçalves Laura P. Garcia Patrícia Garcia 《Journal of environmental science and health. Part. B》2013,48(3):169-175
This study evaluated the influence of the clomazone herbicide (2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone) contamination on the hematological parameters and histological changes in gills and liver of silver catfish (Rhamdia quelen) from Madre River, Santa Catarina State, Southern Brazil. Fish were collected between March 2010 and January 2012 at two different sites of the Madre River, one site receiving residual water (contaminated site) from rice culture (n = 49) and another that do not receive residual water (reference site) (n = 48). The herbicide clomazone analysis detected 3.40 ± 1.70 μg/L in the contaminated site and 1.1 ± 0.33 μg/L in the reference site. Fish from contaminated site showed increased (P < 0.05) number of monocytes suggesting the possible defense response as a result of chronic exposure to clomazone. On the other hand, no difference was found in the hematocrit percentage, red blood cell count, total thrombocyte number, white blood cell count, lymphocytes, and neutrophils number. Fish from both sites showed histopathological changes in gills and liver, possibly caused by chronic exposure to contamination. The influence of herbicide sub doses on fish health is also discussed. 相似文献
715.
Meike Linnenschmidt Laura N. Kloepper Magnus Wahlberg Paul E. Nachtigall 《Die Naturwissenschaften》2012,99(9):767-771
Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8?m distance in a go/no-go paradigm. On-axis clicks had source levels of 145–174?dB re 1?μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4?m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100?ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise. 相似文献
716.
Isabella Fabietti Giulia Grassini Sara Savelli Roberta Vicario Anita Romiti Milena Viggiano Chiara Vassallo Laura Valfrè Paola Giliberti Irma Capolupo Marco Bonito Pietro Bagolan Francesco Morini Leonardo Caforio 《黑龙江环境通报》2023,43(8):1002-1007