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- Hillier, Ladeana W, et al.
(författare)
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
- 2004
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
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Tidskriftsartikel (refereegranskat)abstract
- We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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2. |
- Cheng, Yuanji, et al.
(författare)
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Remarks on bifurcation in elliptic boundary value problems
- 2003
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Ingår i: International Conference on Differential Equations. - : World Scientific. ; , s. 1051-1055
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present some observations of biurcation in nonlinear elliptic boundary value problem - ∆u = f(λ, u) in domain Ω, and u = 0 on the boundary ∂Ω. We are interested in how solution(s) depends on the parameter λ. Through examples, we show that multiple solutions appear, when λ cross certain critical value, i.e. bifurcation occurs.
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3. |
- Wang, Lina
(författare)
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Computational Stability and Adaptive Strategies - An Experimental Study of ODE Software
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The algorithmic content of adaptive ODE/DAE software is dominated by a considerable amount of control structures, support algorithms and logic. The control logic has been largely heuristic and lacking support by analysis. In this thesis we study adaptive time-stepping based on control theory, combined with other carefully selected control strategies. Thus we argue that ODE/DAE software can be constructed and analyzed by proven, "standard" scientific techniques instead of heuristics. We show that carefully designed adaptive algorithms have a most significant impact on the reliability and computational stability of ODE/DAE codes. The latter notion implies that minor changes of the computational setup must only lead to small changes in the computed result: the software must be computationally well-conditioned. A series of computational experiments with the standard implementations of DASSL and RADAU5 are compared to results obtained with modified versions of these codes, where the improved strategies build on the theory mentioned above. These include stepsize control based on digital filters. The experiments demonstrate that these "minor" algorithmic changes strongly improve computational stability at no extra computational expense.
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