A simple and effective automatic focusing algorithm is proposed in this article. The principle of the proposed automatic focusing algorithm is based on that, for the radial test pattern, a best-focused image should ha...
详细信息
A simple and effective automatic focusing algorithm is proposed in this article. The principle of the proposed automatic focusing algorithm is based on that, for the radial test pattern, a best-focused image should have the smallest blurred region in the middle of the acquired image, and hence, should have the smallest equivalent radius. The circular Hough transform has became a common method in numerous image-processing applications for circle detection. Various modifications to the basic circular Hough transform have been suggested, such as: the inclusion of edge orientation, simultaneous consideration of a range of circle radii, the use of a complex accumulator array with the phase proportional to the log of the radius, or for filter operations. The purpose of this work is to show that a radius of a circular region extracted by a normalized circular Hough transform is a possible solution for determining the sharpness of images. To acquire high quality images with a given CCD camera, it is crucial that the camera be located exactly at the back length of the lens, i.e., the focus position of the lens. In the best conditions, the contours of the acquired images are of the sharpest, with none of the blurring effects associated with unfocused images. Acquiring such high quality images by these means is the main goal of the automatic focusing algorithm proposed in this article. (C) 2003 Wiley Periodicals, Inc.
The terminal functional of a general control system is refined by studying an analogous problem for a variational system and regularization. A sequential refinement method is designed by combining the local approximat...
详细信息
The terminal functional of a general control system is refined by studying an analogous problem for a variational system and regularization. A sequential refinement method is designed by combining the local approximation of the reachability set and reduction. The corresponding algorithm has relaxation properties. An illustrative example is given.
A computer algorithm, p53MH, was developed, which identifies putative p53 transcription factor DNA-binding sites on a genome-wide scale with high power and versatility. With the sequences from the human and mouse geno...
详细信息
A computer algorithm, p53MH, was developed, which identifies putative p53 transcription factor DNA-binding sites on a genome-wide scale with high power and versatility. With the sequences from the human and mouse genomes, putative p53 DNA-binding elements were identified in a scan of 2,583 human genes and 1,713 mouse orthologs based on the experimental data of el-Deiry et al. [el-Deiry, W. S., Kern, S. E., Pietenpol, J. A., Kinzler, K. W. & Vogelstein, B. (1992) Nat. Genet 1, 45-49] and Funk et al. [Funk, W. D., Pak, D. T., Karas, R. H., Wright, W. E. & Shay, J. W. (1992) Mol. Cell. Biol. 12, 2866-2871] (http://***/p53). The p53 DNA-binding motif consists of a 10-bp palindrome and most commonly a second related palindrome linked by a spacer region. By scanning from the 5' to 3' end of each gene with an additional 10-kb nucleotide sequence appended at each end (most regulatory DNA elements characterized in the literature are in these regions), p53MH computes the binding likelihood for each site under a discrete discriminant model and then outputs ordered scores, corresponding site positions, sequences, and related information. About 300 genes receiving scores greater than a theoretical cut-off value were identified as potential p53 targets. Semiquantitative reverse transcription-PCR experiments were performed in 2 cell lines on 16 genes that were previously unknown regarding their functional relationship to p53 and were found to have high scores in either proximal promoter or possible distal enhancer regions. Ten (similar to63%) of these genes responded to the presence of p53.
This paper extends the A* methodology to shortest path problems in dynamic networks, in which arc travel times are time dependent. We present efficient adaptations of the A* algorithm for computing fastest (minimum tr...
详细信息
This paper extends the A* methodology to shortest path problems in dynamic networks, in which arc travel times are time dependent. We present efficient adaptations of the A* algorithm for computing fastest (minimum travel time) paths from one origin node to one destination node, for one as well as multiple departure times at the origin node, in a class of dynamic networks the link travel times of which satisfy the first-in-first-out property. We summarize useful properties of dynamic networks and develop improved lower bounds on minimum travel times. These lower bounds are exploited in designing efficient adaptations of the A* algorithm to solve instances of the one-to-one dynamic fastest path problem. The developed algorithms are implemented and their computational performance is analyzed experimentally. The performance of the computer implementations of the adaptations of the A* algorithm are compared to a dynamic adaptation of Dijkstra's algorithm, stopped when the destination node is selected. Comparative computational results obtained demonstrate that the algorithms of this paper are efficient. Using a network containing 3000 nodes, 10000 links, and 100 time intervals, the dynamic adaptations of the A* led to a savings ratio of 11, in terms of number of nodes selected, and to a savings ratio of five in terms of computation time. The effect of the network size on the performance of these adaptations is also studied. It is shown that the computational savings in term of both the number of nodes selected and the computation time, increase with the size of the network topology.
A well-known common problem on the design of a stabilizing control law for a linear system with unknown parameters is studied. For an object given in input-output form with Hurwitz numerator, an approach based on robu...
详细信息
A well-known common problem on the design of a stabilizing control law for a linear system with unknown parameters is studied. For an object given in input-output form with Hurwitz numerator, an approach based on robust control algorithms is developed to stabilize a linear uncertain system using only output measurements. The control system is simple in implementation and the dimension of the controller is one less than the degree of the object.
Microarray analyses are providing a plethora of data concerning transcriptional responses to specific gene regulators and their inducers but do not distinguish between direct and indirect responses. Here, we identify ...
详细信息
Microarray analyses are providing a plethora of data concerning transcriptional responses to specific gene regulators and their inducers but do not distinguish between direct and indirect responses. Here, we identify directly activated promoters of the overlapping marA , soxS and rob regulon(s) of Escherichia coli by applying informatics, genomics and molecular genetics to microarray data obtained by others. Those studies found that overexpression of marA , or the treatment of cells with salicylate to derepress marA , or treatment with paraquat to induce soxS , resulted in elevated transcription of 153 genes. However, only 27 out of the promoters showed increased transcription under at least two of the aforementioned conditions and eight of those were previously known to be directly activated. A computer algorithm was used to identify potential activator binding sites located upstream of the remaining 19 promoters of this subset, and conventional genetic and biochemical approaches were applied to test whether these sites are critical for activation by the homologous MarA, SoxS and Rob transcriptional activators. Only seven out of the 19 promoters were found to be activated when fused to lacZ and tested as single lysogens. All seven contained an essential activator binding site. The remaining promoters were insensitive to stimulation by the inducers suggesting that the great majority of elevated microarray transcripts either were misidentified or resulted from indirect effects requiring sequences outside of the promoter region. We estimate that the total number of directly activated promoters in the regulon is less than 40.
作者：
Iwata, SUniv Tokyo
Grad Sch Informat Sci & Technol Dept Math Informat Tokyo 1138656 Japan
This paper presents a strongly polynomial algorithm for submodular function minimization using only additions, subtractions, comparisons, and oracle calls for function values. (C) 2001 Elsevier Science (USA).
This paper presents a strongly polynomial algorithm for submodular function minimization using only additions, subtractions, comparisons, and oracle calls for function values. (C) 2001 Elsevier Science (USA).
Malicious attacks on Web servers by intruders and hackers are prime concerns of organizations, administrators of Web sites, as well as users who access them.
Malicious attacks on Web servers by intruders and hackers are prime concerns of organizations, administrators of Web sites, as well as users who access them.
In irregular all-to-all communication, messages are exchanged between every pair of processors. The message sizes vary from processor to processor and are known only at run time. This is a fundamental communication pr...
详细信息
In irregular all-to-all communication, messages are exchanged between every pair of processors. The message sizes vary from processor to processor and are known only at run time. This is a fundamental communication primitive in parallelizing irregularly structured scientific computations. Our algorithm reduces the total number of message start-ups. It also reduces node contention by smoothing out the lengths of the messages communicated. As compared to the earlier approaches, our algorithm provides deterministic performance and also reduces the buffer space at the nodes during message passing, The performance of the algorithm is characterised using a simple communication model of high-performance computing (HPC) platforms. We show the implementation on T3D and SP2 using C and the message passing interface standard. These can be easily ported to other HPC platforms. The results show the effectiveness of the proposed technique as well as the interplay among the machine size, the variance in message length, and the network interface. (C) 2002 Elsevier Science (USA).
A vital step in the creation of a visual language is adequate empirical evidence to support any claimed advantages. To this end, the effects of visualisation when applied to the domain of algebraic specifications are ...
详细信息
A vital step in the creation of a visual language is adequate empirical evidence to support any claimed advantages. To this end, the effects of visualisation when applied to the domain of algebraic specifications are investigated through an experiment designed to compare the comprehensibility of one textual and two visual approaches. A statistical analysis of the results is presented and conclusions are drawn regarding the relative worth of the differing approaches. (C) 2002 Elsevier Science Ltd. All rights reserved.
暂无评论