Evaluation of ecotoxicological effects of endocrine disrupters during a four-year survey of the Mediterranean population of swordfish (Xiphias gladius)     

M. Cristina Fossi  Silvia Casini  Letizia Marsili  Stefania Ancora  Gabriele Mori  Giovanni Neri  Teresa Romeo  Antonella Ausili 《Marine environmental research》2004,58(2-5):425

In this project we investigated the ecotoxicological effects of endocrine disrupters in a four-year survey of the Mediterranean population of swordfish (Xiphias gladius). In the Mediterranean environment, top predators, such as swordfish, accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, potentially incurring high toxicological risk. The effects of organochlorines and trace elements (Hg, Cd and Pb) in 192 swordfish specimens, caught in the Strait of Messina, Sicily, Italy, were investigated using vitellogenin (Vtg), zona radiata proteins (Zrp) and CYP1A (BPMO, EROD) activities. Vtg and Zrp were found to be dramatically induced in some adult male specimens, suggesting that this species is highly exposed to estrogens in the Mediterranean Sea. A role of organochlorines in this induction phenomenon is suggested by the statistically significant correlations between Zrp in plasma and PCB concentrations in muscle (p<0.032) and Vtg in plasma and PCB concentrations in liver (p<0.034) of male specimens. Levels of trace elements in liver were in the following ranges: Hg 1–22, Cd 1–28 and Pb 0–1.6 ppm d.w. These data indicate potential reproductive alterations in large pelagic fish and suggest the need for continuous monitoring to avoid reductions in the population of this fish species of high commercial and ecological interest.  相似文献   

健跳港上游引水对海床冲淤影响的数值模拟分析     

唐子文  黄世昌 《海洋学研究》2007,25(1):23-33

健跳港是一个狭长的淤泥质港汊,针对枯季和洪季健跳港海床不同的冲淤特点,利用一维潮流泥沙模型复演了该港海床的冲淤过程,通过调整挟沙力系数来模拟健跳港枯水期的淤积和洪水期的冲刷这两种不同的海床变化形态,并预测了健跳港上游引水后对该港河床的淤积影响。  相似文献   

Integrated methodology for determining provenance of detrital quartz using optical petrographic microscopy and cathodoluminescence (CL) properties     

《Marine and Petroleum Geology》2017

The provenance of detrital quartz is a useful predictor in frontier basin sandstone reservoirs of the availability of coarse-grained quartz grains of plutonic or high grade metamorphic origin. The standard approach is to use scanning electron microscope (SEM) panchromatic cathodoluminescence (CL) imagery and observations from an optical petrographic microscope. We describe a work flow, modified from previous literature proposals, to determine quartz provenance in detrital grains using optical petrographic microscopy and CL properties from both a hot-cathode cathodoluminescence microscope attachment (HCMA) and panchromatic SEM-CL. HCMA analysis permits better discrimination of different types of metamorphic quartz. This method is applied to a Middle Jurassic to Lower Cretaceous section in the Bandol-1 wildcat well, located in the Laurentian sub-basin south of Newfoundland. Two types of high-grade metamorphic quartz are distinguished, one with low luminescence as described in previous literature and one with medium blue CL colour and a moderate colour shift that is also known from granulite in the hinterland. Three phases of detrital supply are identified, suggesting progressive unroofing of higher grade metamorphic sources through the middle Jurassic and major input of plutonic quartz in the early Cretaceous.  相似文献   

Search for radio pulsations in four anomalous X-ray pulsars and discovery of two new pulsars     

Marta Burgay  Nanda Rea  GianLuca Israel  Andrea Possenti  Luciano Burderi  Tiziana Di Salvo  Nichi D’Amico  Luigi Stella  Elisa Nichelli 《Astrophysics and Space Science》2007,308(1-4):531-534

We have performed deep searches for radio pulsations from four southern anomalous X-ray pulsars (AXPs) to investigate their physical nature in comparison with the rotation powered pulsars. The data were acquired using the Parkes radio telescope with the 1.4 GHz multibeam receiver. No pulsed emission with periodicity matching the X-ray ephemeris have been found in the observed targets down to a limit of ∼0.1 mJy. A blind search has also been performed on all the 13 beams of the multibeam receiver (the central beam being pointed on the target AXP), leading to the serendipitous discovery of two new radio pulsars and to the further detection of 18 pulsars. Also a search for single dispersed pulses has been performed in the aim to detect signals similar to those of the recently discovered rotating radio transients.   相似文献   

HESS observations of extragalactic objects     

Matthias Beilicke 《Astrophysics and Space Science》2007,309(1-4):139-145

The HESS experiment (High Energy Stereoscopic System), consisting of four imaging atmospheric Cherenkov telescopes (IACTs) in Namibia, has observed many extragalactic objects in the search for very high energy (VHE) γ-ray emission. These objects include active galactic nuclei (AGN), notably Blazars, Seyferts, radio galaxies, starburst galaxies and others. Beyond the established sources, γ-ray emission has been detected for the first time from several of these objects by HESS, and their energy spectra and variability characteristics have been measured. Multi-wavelength campaigns, including X-ray satellites, radio telescopes, and optical observations, have been carried out for AGNs, in particular for PKS 2155-304, H 2356-309 and 1ES 1101-232, for which the implications concerning emission models are presented. Also results from the investigations of VHE flux variability from the giant radio galaxy M 87 are shown. For the HESS Collaboration.  相似文献   

Detection of a 1258-Hz high-amplitude kilohertz quasi-periodic oscillation in the ultracompact X-ray binary 1A 1246–588     

P. G. Jonker  J. J. M. in't Zand  M. Méndez  M. van der Klis 《Monthly notices of the Royal Astronomical Society》2007,378(3):1187-1190

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Near-infrared light curve of Comet 9P/Tempel 1 during Deep Impact     

Y.R. Fernández  C.M. Lisse  N. Dello Russo  C.E. Woodward 《Icarus》2007,187(1):220-227

On UT 2005 July 4 we observed Comet 9P/Tempel 1 during its encounter with the Deep Impact flyby spacecraft and impactor. Using the SpeX near-infrared spectrograph mounted on NASA's Infrared Telescope Facility, we obtained 0.8-to-2.5 μm flux-calibrated spectral light curves of the comet for 12 min before and 14 min after impact. Our cadence was just 1.1 s. The light curve shows constant flux before the impact and an overall brightening trend after the impact, but not at a constant rate. Within a 0.8-arcsec-radius circular aperture, the comet rapidly-brightened by 0.63 mag at 1.2 μm in the first minute. Thereafter, brightening was more modest, averaging about 0.091 mag/min at 1.2 μm, although apparently not quite constant. In addition we see a bluing in the spectrum over the post-impact period of about 0.07 mag in J-H and 0.35 mag in J-K. The majority of this bluing happened in the first minute, and the dust only marginally blued after that, in stark contrast to the continued brightening. The photometric behavior in the light curve is due to a combination of crater formation effects, expansion of the ejecta cloud, and evolution of liberated dust grains. The bluing is likely due to an icy component on those grains, and the icy grains would have had to have a devolatilization timescale longer than 14 min (unless they were shielded by the optical depth of the cloud). The bluing could also have been caused by the decrease in the “typical” size of the dust grains after impact. Ejecta dominated by submicron grains, as inferred from other observations, would have stronger scattering at shorter wavelengths than the much larger grains observed before impact.  相似文献   

三峡库首区最小一维速度模型研究   总被引：3，自引：0，他引：3  

赵旭  李强  蔡晋安 《大地测量与地球动力学》2007,27(Z1):1-7

根据三峡台网2001～2006年记录的490个地震事件中的7 330条P波和3 524条S波到时资料,利用Kissling方法得到了三峡库区最小一维P波和S波速度模型以及台站校正值,并应用于地震的精定位.重新定位后地震走时残差均方根从原来的0.56 s下降到0.41 s,地震定位精度在经度、纬度、深度方向上有了较大提高.  相似文献   

The shape, topography, and geology of Tempel 1 from Deep Impact observations     

Peter C. Thomas  J. Veverka  Alan Hidy  T.L. Farnham  Jian-Yang Li  Jessica Sunshine  Carey Lisse  Karen J. Meech 《Icarus》2007,187(1):4-15

Deep Impact images of the nucleus of Comet Tempel 1 reveal pervasive layering, possible impact craters, flows with smooth upper surfaces, and erosional stripping of material. There are at least 3 layers 50-200 m thick that appear to extend deep into the nucleus, and several layers 1-20 m thick that parallel the surface and are being eroded laterally. Circular depressions show geographical variation in their forms and suggest differences in erosion rates or style over scales >1 km. The stratigraphic arrangement of these features suggests that the comet experienced substantial periods of little erosion. Smooth surfaces trending downslope suggest some form of eruption of materials from this highly porous object. The Deep Impact images show that the nucleus of Tempel 1 cannot be modeled simply as either an onion-layer or rubble pile structure.  相似文献   

A MERLIN Study of 6-GHz excited-state OH and 6.7-GHz methanol masers in ON1     

J. A. Green  A. M. S. Richards  W. H. T. Vlemmings  P. Diamond  R. J. Cohen † 《Monthly notices of the Royal Astronomical Society》2007,382(2):770-778

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