Invasion genetics of Pacific oyster Crassostrea gigas shaped by aquaculture stocking practices     

Jenny Moehler  K. Mathias Wegner  Karsten Reise  Sabine Jacobsen 《Journal of Sea Research》2011,66(3):256-262

As a result of aquaculture activities Pacific oysters Crassostrea gigas (Thunberg, 1793) have invaded the European Wadden Sea. Using a variable noncoding mitochondrial marker, we show that the invaded range is the result of two independent invasions. Haplotype frequencies point towards two separate groups, one in the southern and the other in the northern Wadden Sea. We found virtually no genetic differentiation throughout the southern range and the putative source from British Columbia, Canada, suggesting that the Southern region can be considered as a closed population. In the North, mismatch distributions, haplotype ordination and isolation-by-distance analysis suggest a stronger, persistent impact of aquaculture on invasive populations. Due to the ongoing supply of new genetic material from hatchery production the northern invasive populations can therefore be considered as an open population highlighting the importance of aquaculture practice on the genetics of this keystone invader in the Wadden Sea.  相似文献   

The NOAO Fundamental Plane Survey – III. Variations in the stellar populations of red-sequence galaxies from the cluster core to the virial radius     

Russell J. Smith  Michael J. Hudson  John R. Lucey  Jenica E. Nelan  Gary A. Wegner 《Monthly notices of the Royal Astronomical Society》2006,369(3):1419-1436

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Comparison of the ENEAR peculiar velocities with the PSCz gravity field     

Adi Nusser  Luiz N. da Costa  Enzo Branchini  Mariangela Bernardi  M.V. Alonso  Gary Wegner  C. N. A. Willmer  P. S. Pellegrini 《Monthly notices of the Royal Astronomical Society》2001,320(3):L21-L24

We present a comparison between the peculiar velocity field measured from the ENEAR all-sky D _n– σ catalogue and that derived from the galaxy distribution of the IRAS Point Source Catalog Redshift Survey (PSC z ). The analysis is based on a modal expansion of these data in redshift space by means of spherical harmonics and Bessel functions. The effective smoothing scale of the expansion is almost linear with redshift reaching 1500 km s⁻¹ at 3000 km s⁻¹. The general flow patterns in the filtered ENEAR and PSC z velocity fields agree well within 6000 km s⁻¹, assuming a linear biasing relation between the mass and the PSC z galaxies. The comparison allows us to determine the parameter     where Ω is the cosmological density parameter and b is the linear biasing factor. A likelihood analysis of the ENEAR and PSC z modes yields     in good agreement with values obtained from Tully–Fisher surveys.  相似文献   

Evaluation of a component of the cloud response to climate change in an intercomparison of climate models     

K. D. Williams  M. A. Ringer  C. A. Senior  M. J. Webb  B. J. McAvaney  N. Andronova  S. Bony  J. -L. Dufresne  S. Emori  R. Gudgel  T. Knutson  B. Li  K. Lo  I. Musat  J. Wegner  A. Slingo  J. F. B. Mitchell 《Climate Dynamics》2006,26(2-3):145-165

Most of the uncertainty in the climate sensitivity of contemporary general circulation models (GCMs) is believed to be connected with differences in the simulated radiative feedback from clouds. Traditional methods of evaluating clouds in GCMs compare time–mean geographical cloud fields or aspects of present-day cloud variability, with observational data. In both cases a hypothetical assumption is made that the quantity evaluated is relevant for the mean climate change response. Nine GCMs (atmosphere models coupled to mixed-layer ocean models) from the CFMIP and CMIP model comparison projects are used in this study to demonstrate a common relationship between the mean cloud response to climate change and present-day variability. Although atmosphere–mixed-layer ocean models are used here, the results are found to be equally applicable to transient coupled model simulations. When changes in cloud radiative forcing (CRF) are composited by changes in vertical velocity and saturated lower tropospheric stability, a component of the local mean climate change response can be related to present-day variability in all of the GCMs. This suggests that the relationship is not model specific and might be relevant in the real world. In this case, evaluation within the proposed compositing framework is a direct evaluation of a component of the cloud response to climate change. None of the models studied are found to be clearly superior or deficient when evaluated, but a couple appear to perform well on several relevant metrics. Whilst some broad similarities can be identified between the 60°N–60°S mean change in CRF to increased CO₂ and that predicted from present-day variability, the two cannot be quantitatively constrained based on changes in vertical velocity and stability alone. Hence other processes also contribute to the global mean cloud response to climate change.  相似文献   

Nanometric modulation in apatite     

C. Ferraris  T. J. White  J. Plévert  R. Wegner 《Physics and Chemistry of Minerals》2005,32(7):485-492

Brazilian gem-grade apatite (B-Ap) consists of contiguous fluorine-enriched (host-Ap) domains (∼400 nm), interspersed by isolated domains (∼200 nm) of a chlorine-enriched (guest-Ap) apatite in a long period compositional modulation. Within each of these domains a third modulation differentiating Si- and S-rich nanocrystals (5–10 nm) of ellestadite (El-Ap), a monoclinic apatite variety, developed possibly during a short term high temperature event. These unexpected miscibility gaps may be useful geothermometric tools, and could prove decisive for enhancing the properties of apatites used as heterogeneous catalysts and fuel–cell electrolytes.  相似文献   

The Oxford–Dartmouth Thirty Degree Survey – I. Observations and calibration of a wide-field multiband survey     

Emily C. MacDonald  Paul Allen  Gavin Dalton  Leonidas A. Moustakas  Catherine Heymans  Edward Edmondson  Chris Blake  Lee Clewley  Molly C. Hammell  Ed Olding  Lance Miller  Steve Rawlings  Jasper Wall  Gary Wegner  Christian Wolf 《Monthly notices of the Royal Astronomical Society》2004,352(4):1255-1272

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Bathymetric chart of Atka Ice Port     

Gerd Wegner 《Ocean Dynamics》1981,34(4):162-166

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Zum Verlauf der Oberflächentemperaturen der Nordsee von Ende Oktober 1992 bis Ende Juni 1993     

Gerd Wegner 《Ocean Dynamics》1993,45(3):203-210

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Exsolution in terrestrial and lunar plagioclases revealed by chemical etching     

M. W. Wegner  R. E. Jones  J. M. Christie 《Contributions to Mineralogy and Petrology》1978,65(3):283-291

A new chemical etching technique reveals fine scale exsolution structures on polished surfaces of plagioclases in the bytownite and labradorite range. A very obvious blue and locally brown stain is produced (by the action of citric acid) in growth zones of a restricted range of compositions on etched surfaces. The blue-stained zones contain very fine grooves, corresponding to the traces of thin exsolution lamellae. Exsolution features have been revealed in this way in plagioclases in a terrestrial diabase, lunar basalts and an amphibolite. Compositions of the exsolved areas found by microprobe analysis represent averages of the matrix and exsolution lamellae. Analytical methods with higher spatial resolution are required to determine the composition of the lamellae. This etching method permits easy optical identification of compositional zoning and of fine scale exsolution over relatively large areas and is therefore complementary to other techniques.  相似文献   

Chemical etching of dislocations in forsterite     

M. W. Wegner  J. M. Christie 《Contributions to Mineralogy and Petrology》1976,59(2):131-140

Chemical etching of pure melt-grown forsterite crystals is reported here for the first time. Cleaved forsterite crystals of known purity, and polished sections of the same crystals have been successfully etched revealing dislocations, subgrain boundaries, inclusions and growth imperfections.  相似文献