Evolution sequence

Families of similar sequences contain information on sequence evolution in the form of specific conservation patterns at all sequence positions. Multiple sequence alignments are useful for... 

Clarifying Problems in the Description of Pre Main Sequence Evolution... 

DNA-sequence evolution mutation and variation in the human genome Computer-assisted phylogenetic analysis large genomic regions... 

Ascending and descending branches of sequence evolution. The aim of the study [70] was to introduce explicitly the concept of sequence evolution into the CDSD scheme. 

Fig. 11 a Mean square gyration radius and b Jensen-Shannon divergence measure as a function of the attraction energy pp between hydrophilic segments, after the sequence evolution procedure. The characteristic energy of H - H interactions is fixed at hh = 2/cbT, thus stabilizing a dense globular core. Adapted from [70]... 

A. Selection from Libraries with or without Concurrent Sequence Evolution 1. Peptide Display... 

J. C. Evans, Stellar post-main sequence evolution, http //www.physics.gmu.edu/classinfo/ astrl03/CourseNotes/Text/Lec05/Lec05 pt5 txt stellarPostMSEvol.htm... 

Itis ofinterestthatLi is easily destroyed by (p, alpha) reactions atT = 2.5 MK or greater, so that when newly born stars arrive on the Main Sequence, they have already destroyed Li throughout most of their interiors by these nuclear interactions in the deep convection of the pre-Main-Sequence evolution. The observed Li has survived only in the outermost few percent by mass of the interior of the stars. 

A statistical mechanical model of thermodynamic entropy production in a sequence-structure system suggests that the shared thermodynamic entropy is the probability function that weighs any sequence average. The sequence information is defined as the length of the shortest string that encodes the sequence. The connection between sequence evolution and nonequilibrium thermodynamics is that the minimal length encoding of specific amino acids will have the same dependence on sequence as the shared thermodynamic entropy. 

Fig. 4. The pre-main sequence evolution of 0.5 to 1.5 solar mass stars in the Hertzsprung-Russell diagram. The lines represent theoretical evolutionary tracks, while the dots represent observational data for T Tauri stars (Cohen and Kuhi, 1979). The corresponding ages and ratios of UV flux to present solar UV flux are indicated for a solar-mass star.

Clearly slice selection and phase encoding form part of the preparation segment of the sequence, evolution occurs under the influence of the PGSE pulse pair, and detection occurs in the presence of the read gradient. Given excitation of a single slice, the number of dimensions is reduced to two in k space and one in q space. We may combine all these influences to write... 

Due to the degeneracy of the HRD positions during the main sequence evolution (see Fig. 8), a comparison of the observed stellar boron abundances and effective temperatures... 

Finally, we want to emphasise that, although stars of less than 1.3 M lose 99% of their angular momentum due to a magnetic wind during their main sequence evolution, it can not be excluded that the proposed mechanism of 13C-production due to differential... 

A further striking feature shown in Fig. 20 is the convergence of the rotational velocities to the value of v( nt,iinm (i.e., lOOkrns ), which is produced by the fact that the time dependence of the critical rotational velocity is almost independent of the mass loss history, in particular its minimum value. Note, however, that although the rotation velocities of the four sequences displayed in Fig. 20 at the end of the main sequence evolution are almost identical, their masses at that time are greatly different, and thus their ensuing post-main sequence evolution is expected to be very different as well. 

Schematically, during main sequence evolution, the fast wind creates a cavity in the interstellar medium and sweeps out a shell of compressed gas. After departure from the main sequence, the nature of the mass loss changes and the star loses chemically enriched material. When the star reaches the Wolf-Rayet phase, its outer layers are almost hydrogen free. This material is lost at high velocity and catches up with material lost in previous stages (see Chu 1991 or Marston 1999 for a review).

Smith, N.H., Maynard-Smith, J., and Spratt, B.G. (1995). Sequence evolution of the porB gene of Neisseria gonorrhoeae and N. memingitidis Evidence of positive Darwinian selection. Mol, Biol. Evol. 72 363-370. 

Convection occurs in the core when the CNO cycle contributes more than ss 20% of the total energy output, since n T17 implies that the temperature gradient in the core is very steep. The fact that stars in the 1 — 1.4 M range can develop CNO burning during main-sequence evolution also implies that such stars (including the Sun) may develop a convective core. 

Second, the shape of the evolution track is altered. In a star with a radiative core nuclear burning shifts smoothly from the hydrogen-depleted core to a thick hydrogen-poor shell and then to a thin hydrogen-rich shell. The transition from main-sequence to post main-sequence evolution is comparatively smooth (Fig. 8). In a star with a convective core, nuclear burning switches off abruptly as the entire convective core is exhausted. This precipitates a minor collapse of the depleted core before ignition of the hydrogen shell, and produces a hook in the evolution track at the end of main-sequence evolution. 

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