Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí y học Molecular Biology cung cấp cho các bạn kiến thức về ngành sinh học đề tài: Local sequence alignments statistics: deviations from Gumbel statistics in the rare-event tail. | Algorithms for Molecular Biology BioMed Central Research Open Access Local sequence alignments statistics deviations from Gumbel statistics in the rare-event tail Stefan Wolfsheimer 1 2 Bernd Burghardt1 and Alexander K Hartmann1 2 Address 1Institut fur Theoretische Physik Universitat Gottingen 37077 Gottingen Friedrich-Hund-Platz 1 Germany and 2Institut fur Physik Universitat Oldenburg 26111 Oldenburg Germany Email Stefan Wolfsheimer - wolfsh@ Bernd Burghardt - burghard@ Alexander K Hartmann - Corresponding author Published II July 2007 Received 5 October 2006 Algorithms for Molecular Biology 2007 2 9 doi 1748-7188-2-9 Accepted 11 July 2007 This article is available from http content 2 1 9 2007 Wolfsheimer et al licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Background The optimal score for ungapped local alignments of infinitely long random sequences is known to follow a Gumbel extreme value distribution. Less is known about the important case where gaps are allowed. For this case the distribution is only known empirically in the high-probability region which is biologically less relevant. Results We provide a method to obtain numerically the biologically relevant rare-event tail of the distribution. The method which has been outlined in an earlier work is based on generating the sequences with a parametrized probability distribution which is biased with respect to the original biological one in the framework of Metropolis Coupled Markov Chain Monte Carlo. Here we first present the approach in detail and evaluate the convergence of the algorithm by considering a simple test case. In the earlier work .
