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Li A.-M.,CAS South China Botanical Garden | Li A.-M.,Huaihua College | Wu X.-Q.,CAS South China Botanical Garden | Zhang D.-X.,CAS South China Botanical Garden | Barrett S.C.H.,University of Toronto
Annals of Botany | Year: 2010

Background and Aims: Evolutionary transitions from heterostyly to dioecy have been proposed in several angiosperm families, particularly in Rubiaceae. These transitions involve the spread of male and female sterility mutations resulting in modifications to the gender of ancestral hermaphrodites. Despite sustained interest in the gender strategies of plants, the structural and developmental bases for transitions in sexual systems are poorly understood. Methods: Here, floral morphology, patterns of fertility, pollen-tube growth and floral development are investigated in two populations of the scandent shrub Mussaenda pubescens (Rubiaceae), native to southern China, by means of experimental and open-pollinations, light microscopy, fluorescence microscopy and scanning electron microscopy combined with paraffin sectioning. Key Results Mussaenda pubescens: has perfect (hermaphroditic) flowers and populations with two style-length morphs but only weak differentiation in anther position (stigma-height dimorphism). Experimental pollinations demonstrated that despite morphological hermaphroditism, the species is functionally dioecious. The long-styled (L) morph possesses sterile pollen and functions as a female, whereas the short-styled (S) morph is female sterile and functions as a male. Self- and intra-morph pollinations of the S-morph were consistent with those expected from dimorphic incompatibility. The two populations investigated were both S-morph (male) biased. Investigations of early stages of floral development indicated patterns typical of hermaphroditic flowers, with no significant differences in organ growth between the floral morphs. Meiosis of microspore mother cells was of the simultaneous type with tetrads isobilateral in shape. The tapetal cells in anther walls of the L-morph became vacuolized during meiosis I, ahead of the uninucleate microspore stage in the S-morph. In the L-morph, the microspore nucleus degenerated at the tetrad stage resulting in male sterility. Microsporogenesis and male gametophyte development was normal in the S-morph. Failure in the formation of megaspore mother cells and/or the development of megagametophytes resulted in female sterility in the S-morph, compared with normal megasporogenesis in the L-morph. Conclusions In M. pubescens: cryptic dioecy has evolved from stigma-height dimorphism as a result of morph-specific sterility mutations. © The Author 2010. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. Source


Wei G.,Huaihua College | Shen J.,Hangzhou Normal University
Computers and Mathematics with Applications | Year: 2010

This paper is concerned with the nonlinear delay difference equations with positive and negative coefficients x(n+1)-x(n)+p(n)f(x(n-k))-q(n)f(x(n-l))=0, n Source


Yuan Y.,Huaihua College
Proceedings of the International Conference on E-Business and E-Government, ICEE 2010 | Year: 2010

Substitution effect of tourism product is the phenomenon that some tourism products substitute each others because of their similar value and utility. With the goal to appraise the substitution effect of tourism product quantitatively, the author utilizes the multi-level grey theory which is the synthesis of grey correlation theories and group-decision analytical hierarchy process (AHP). The author also carries out the demonstration study of Wuling and Red Stone Forest, which indicates: there is certain substitution effect between the geological tourism resources groups of Wuling and Red Stone Forest, but Wuling silicarenite resources group has no sufficiently strong substitution effect for Red Stone Forest, so the Wuling Geological tourism resources group has the shielding effect on the Red Stone Forest. Through demonstration study, it is confirmed that application of multi-level grey theory in appraising quantitatively the substitution effect of tourism product is objective and credible, avoiding the disadvantages of analytic hierarchy process. This method provides a feasible quantitative analysis tool for the substitution effect appraisal with small sample and poor information. © 2010 IEEE. Source


Wei G.,Huaihua College
Tamkang Journal of Mathematics | Year: 2014

This paper is concerned with the nonlinear neutral delay differential equation with positive and negative coefficients [x(t )c(t )x(t φ)]′ +p(t ) f (x(t δ))q(t ) f (x(t σ)) = 0, t ≥ t0, where φ ε (0,∞), δ and σ ε [0,∞), c(t ) ε C([t0,σ),R), p(t) and q(t) ε C([t0,σ), [0, σ)), f ε C(R,R). Sufficient conditions are obtained under which every solution of the above equation is bounded and tends to a constant as t → σ. Our results extend and improve some known results. Source


Li J.-C.,National University of Defense Technology | Huang B.,Huaihua College | Peng Y.-X.,National University of Defense Technology
Wuli Xuebao/Acta Physica Sinica | Year: 2012

Bilateral filtering can effectively smooth synthetic aperture radar (SAR) images with preserving the edges, but it is difficult to configure the parameters of bilateral filtering to the optimum. The iterative method to configure the parameters with high precision and efficiency has been presented, but the iterative process may be aborted incorrectly. In this paper, we present a modified configuration method to get the optimal trade-off parameters, and give the proof of the convergence of the method. The experimental results on real SAR images show that the modified method can not only obtain equivalent visibility as the iterative method, but also higher accuracy of the gray value similarity variance than that under identical iterative precision. With the iterative precision improved, the convergence rate of the modified method is faster than that of the iterative method. © Chinese Physical Society. Source

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