Influence of gravity waves on the internal rotation and Li abundance of solar-type stars     

Charbonnel C  Talon S 《Science (New York, N.Y.)》2005,309(5744):2189-2191

The Sun's rotation profile and lithium content have been difficult to understand in the context of conventional models of stellar evolution. Classical hydrodynamic models predict that the solar interior must rotate highly differentially, in disagreement with observations. It has recently been shown that internal waves produced by convection in solar-type stars produce an asymmetric, shear layer oscillation, similar to Earth's quasi-biennial oscillation, that leads to efficient angular momentum redistribution from the core to the envelope. We present results of a model that successfully reproduces both the rotation profile and the surface abundance of lithium in solar-type stars of various ages.  相似文献   

Marine polysaccharides: a source of bioactive molecules for cell therapy and tissue engineering     

Senni K  Pereira J  Gueniche F  Delbarre-Ladrat C  Sinquin C  Ratiskol J  Godeau G  Fischer AM  Helley D  Colliec-Jouault S 《Marine drugs》2011,9(9):1664-1681

The therapeutic potential of natural bioactive compounds such as polysaccharides, especially glycosaminoglycans, is now well documented, and this activity combined with natural biodiversity will allow the development of a new generation of therapeutics. Advances in our understanding of the biosynthesis, structure and function of complex glycans from mammalian origin have shown the crucial role of this class of molecules to modulate disease processes and the importance of a deeper knowledge of structure-activity relationships. Marine environment offers a tremendous biodiversity and original polysaccharides have been discovered presenting a great chemical diversity that is largely species specific. The study of the biological properties of the polysaccharides from marine eukaryotes and marine prokaryotes revealed that the polysaccharides from the marine environment could provide a valid alternative to traditional polysaccharides such as glycosaminoglycans. Marine polysaccharides present a real potential for natural product drug discovery and for the delivery of new marine derived products for therapeutic applications.  相似文献   

Growth characteristics of potato plants useful in studies of population dynamics and biological control of aphids     

W. A. Shands  G. W. Simpson  Corinne C. Gordon 《American Journal of Potato Research》1971,48(12):439-449

During three growing seasons, certain information was recorded weekly that was related to several characteristics of the aerial growth of five varieties of field-growing potatoes, viz. the number of stems and leaves per plant, the length of stems, and leaf area. Conversions of aphid numbers recorded from stratified subsamples of plants in the field to the number of aphids per plant or per unit of leaf area became possible by knowing the number of leaves and the leaf area per plant at the time of each aphid count. The numbers and areas of leaves per plant varied greatly among varieties as well as within and among years. The range in average maximum area of leaves per plant was 533 to 2,523 in.² for the years 1967 to 1969. The comparable range for number of leaves per plant for the years 1967 and 1969 was 53 to 145. Consideration was given to the probable influence upon the magnitude of errors of estimate of aphid abundance that might result in making conversions of field counts of aphids to the numbers of aphids per plant or per unit of leaf area.  相似文献   

Rapid beetle community convergence following experimental habitat restoration in a mined peat bog     

Corinne H. Watts  Beverley R. Clarkson 《Biological conservation》2008,141(2):568-579

The rate of recovery of invertebrate communities following habitat restoration has received little attention, despite the importance of invertebrates in ecosystem dynamics. In experimental trials in a mined peat bog in New Zealand, we compared the short-term rate of beetle community re-assembly at sites restored using management techniques varying in cost and effort to implement, and subsequently examined the long-term rate of beetle community convergence towards the ‘target’ community structure of an undisturbed peat bog. There was a direct relationship between the rate of beetle community re-assembly and the cost and effort applied to plant community restoration treatments (processed peat with no seed, processed peat with seed, and direct habitat translocation). To test the longer term rate of beetle community convergence following habitat restoration, we monitored beetle assemblages on a chronosequence of experimental habitat islands in which restoration was initiated 1, 13, 24, 25, 42 and 72 months previously. With increasing age, the plant community became more diverse and structurally complex, and beetle community composition converged rapidly on the target community structure of an undisturbed peat bog. Using a simple linear regression analysis on ordination axis scores, we obtained the quantitative prediction that the beetle community on restored islands would converge on the average community composition of an undisturbed peat bog within just 7-8.5 years. Our results clearly show that rapid invertebrate community re-assembly can occur in direct response to management techniques focused on establishing vegetation structure. Even the use of a low-cost restoration technique (processed peat with seed added) was effective in initiating remarkably rapid invertebrate community re-assembly in cutover peat bogs within 10 years.  相似文献   

Application of stable carbon isotope analysis to the detection of testosterone administration to cattle     

Hebestreit M  Flenker U  Buisson C  Andre F  Le Bizec B  Fry H  Lang M  Weigert AP  Heinrich K  Hird S  Schänzer W 《Journal of agricultural and food chemistry》2006,54(8):2850-2858

The use of anabolic substances is prohibited in food-producing animals throughout the European Union. No method is available to reliably detect the misuse of natural hormones in cattle. A method was developed to detect the abuse of testosterone in cattle fattening. Synthesized testosterone is rather depleted in the (13)C/(12)C ratio. Hence, the method is based on gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis of urine. To select testosterone metabolites and endogenous reference compounds (ERC), the concentration of urinary steroids of cattle was investigated. Dehydroepiandrosterone and androst-5ene-3beta,17alpha-diol were chosen as ERCs to show endogenous (13)C/(12)C ratios. Etiocholanolone and 5alpha-androstane-3beta,17alpha-diol were chosen as the most important testosterone metabolites. Other metabolites known from literature like epitestosterone were less promising. In principle, GC/C/IRMS is a nonspecific method because finally carbon dioxide is analyzed. Therefore, a dedicated cleanup procedure for the selected steroids was developed. By means of proposed confidence intervals in the isotopic composition of ERCs and metabolites, the administration of testosterone to cattle could be detected reliably. Differences of up to 11 per thousand on the delta-scale between ERC and testosterone metabolites were found after testosterone administration, whereas endogenous differences did not exceed 2 per thousand.  相似文献   

Evaluation of assays for quantification of DNA in canine plasma as an indirect marker of NETosis          下载免费PDF全文

Stephanie A. Smith  Corinne M. Lawson  Maureen A. McMichael  Katrina Jung  Mauria O'Brien  Ron Achiel 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2017,46(2):278-286

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