FFT analysis of DNA sequences Harvey Lab Group Meeting March 1, - - PowerPoint PPT Presentation
FFT analysis of DNA sequences Harvey Lab Group Meeting March 1, - - PowerPoint PPT Presentation
FFT analysis of DNA sequences Harvey Lab Group Meeting March 1, 2004 Russell Hanson 2 Nave string search: FFT sequence analysis implementation 2003.03.01 3 Alignments local and global FFT sequence analysis 2003.03.01 BLAST Two
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Naïve string search: implementation
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Alignments local and global
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BLAST
Two steps: 1) Hash
2) Lookup table
It encodes all the 8-mers as numbers, then it encodes
the search string (i.e. chromosome sequence fragment), then it shifts the 8-mers along the search string, building a lookup table of 8-mers and their locations in the search
- string. For any subsequent search, therefore, you need
- nly compare the hash values of the query string with
the lookup table (avoiding working with the search string ever again).
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Fourier transforms
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Fourier transforms II
This is a matrix vector multiplication, which takes O(n)
- perations.
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Convolution & correlation
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Convolution & correlation II
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FFT Convolution equation
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Convolution theorem
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Base vector encodings
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C Language implementation
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Results
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PSSMs
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Shift-and algorithm
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MAFFT – Multi-Alignment FFT
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FFT for global alignment
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