18,074 research outputs found
Two-Dimensional Pattern Matching with k Mismatches
We give an algorithm which finds all occurrences of an m1 x m2 pattern array embedded as subarrays in an n1 x n2 array of text, where at most k mismatches are allowed per occurrence. The algorithm runs in time O((k+a)(blogb+ n1n2)), where a = min(m1m2) and b=max(m1m2). This improves upon the previously best known algorithm, and is asymptotically optimal for k ≈ a
Thermodynamic behavior of short oligonucleotides in microarray hybridizations can be described using Gibbs free energy in a nearest-neighbor model
While designing oligonucleotide-based microarrays, cross-hybridization
between surface-bound oligos and non-intended labeled targets is probably the
most difficult parameter to predict. Although literature describes
rules-of-thumb concerning oligo length, overall similarity, and continuous
stretches, the final behavior is difficult to predict. The aim of this study
was to investigate the effect of well-defined mismatches on hybridization
specificity using CodeLink Activated Slides, and to study quantitatively the
relation between hybridization intensity and Gibbs free energy (Delta G),
taking the mismatches into account. Our data clearly showed a correlation
between the hybridization intensity and Delta G of the oligos over three orders
of magnitude for the hybridization intensity, which could be described by the
Langmuir model. As Delta G was calculated according to the nearest-neighbor
model, using values related to DNA hybridizations in solution, this study
clearly shows that target-probe hybridizations on microarrays with a
three-dimensional coating are in quantitative agreement with the corresponding
reaction in solution. These results can be interesting for some practical
applications. The correlation between intensity and Delta G can be used in
quality control of microarray hybridizations by designing probes and
corresponding RNA spikes with a range of Delta G values. Furthermore, this
correlation might be of use to fine-tune oligonucleotide design algorithms in a
way to improve the prediction of the influence of mismatching targets on
microarray hybridizations.Comment: 32 pages on a single pdf fil
Robust Motion Segmentation from Pairwise Matches
In this paper we address a classification problem that has not been
considered before, namely motion segmentation given pairwise matches only. Our
contribution to this unexplored task is a novel formulation of motion
segmentation as a two-step process. First, motion segmentation is performed on
image pairs independently. Secondly, we combine independent pairwise
segmentation results in a robust way into the final globally consistent
segmentation. Our approach is inspired by the success of averaging methods. We
demonstrate in simulated as well as in real experiments that our method is very
effective in reducing the errors in the pairwise motion segmentation and can
cope with large number of mismatches
Parametrization of stochastic inputs using generative adversarial networks with application in geology
We investigate artificial neural networks as a parametrization tool for
stochastic inputs in numerical simulations. We address parametrization from the
point of view of emulating the data generating process, instead of explicitly
constructing a parametric form to preserve predefined statistics of the data.
This is done by training a neural network to generate samples from the data
distribution using a recent deep learning technique called generative
adversarial networks. By emulating the data generating process, the relevant
statistics of the data are replicated. The method is assessed in subsurface
flow problems, where effective parametrization of underground properties such
as permeability is important due to the high dimensionality and presence of
high spatial correlations. We experiment with realizations of binary
channelized subsurface permeability and perform uncertainty quantification and
parameter estimation. Results show that the parametrization using generative
adversarial networks is very effective in preserving visual realism as well as
high order statistics of the flow responses, while achieving a dimensionality
reduction of two orders of magnitude
Assessment of a photogrammetric approach for urban DSM extraction from tri-stereoscopic satellite imagery
Built-up environments are extremely complex for 3D surface modelling purposes. The main distortions that hamper 3D reconstruction from 2D imagery are image dissimilarities, concealed areas, shadows, height discontinuities and discrepancies between smooth terrain and man-made features. A methodology is proposed to improve automatic photogrammetric extraction of an urban surface model from high resolution satellite imagery with the emphasis on strategies to reduce the effects of the cited distortions and to make image matching more robust. Instead of a standard stereoscopic approach, a digital surface model is derived from tri-stereoscopic satellite imagery. This is based on an extensive multi-image matching strategy that fully benefits from the geometric and radiometric information contained in the three images. The bundled triplet consists of an IKONOS along-track pair and an additional near-nadir IKONOS image. For the tri-stereoscopic study a densely built-up area, extending from the centre of Istanbul to the urban fringe, is selected. The accuracy of the model extracted from the IKONOS triplet, as well as the model extracted from only the along-track stereopair, are assessed by comparison with 3D check points and 3D building vector data
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