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1.
Our nervous system is confronted with a barrage of sensory stimuli, but neural resources are limited and not all stimuli can be processed to the same extent. Mechanisms exist to bias attention toward the particularly salient events, thereby providing a weighted representation of our environment. Our understanding of these mechanisms is still limited, but theoretical models can replicate such a weighting of sensory inputs and provide a basis for understanding the underlying principles. Here, we describe such a model for the auditory system-an auditory saliency map. We experimentally validate the model on natural acoustical scenarios, demonstrating that it reproduces human judgments of auditory saliency and predicts the detectability of salient sounds embedded in noisy backgrounds. In addition, it also predicts the natural orienting behavior of naive macaque monkeys to the same salient stimuli. The structure of the suggested model is identical to that of successfully used visual saliency maps. Hence, we conclude that saliency is determined either by implementing similar mechanisms in different unisensory pathways or by the same mechanism in multisensory areas. In any case, our results demonstrate that different primate sensory systems rely on common principles for extracting relevant sensory events.  相似文献   

2.
Airport detection in remote sensing images: a method based on saliency map   总被引:1,自引:0,他引:1  
The detection of airport attracts lots of attention and becomes a hot topic recently because of its applications and importance in military and civil aviation fields. However, the complicated background around airports brings much difficulty into the detection. This paper presents a new method for airport detection in remote sensing images. Distinct from other methods which analyze images pixel by pixel, we introduce visual attention mechanism into detection of airport and improve the efficiency of detection greatly. Firstly, Hough transform is used to judge whether an airport exists in an image. Then an improved graph-based visual saliency model is applied to compute the saliency map and extract regions of interest (ROIs). The airport target is finally detected according to the scale-invariant feature transform features which are extracted from each ROI and classified by hierarchical discriminant regression tree. Experimental results show that the proposed method is faster and more accurate than existing methods, and has lower false alarm rate and better anti-noise performance simultaneously.  相似文献   

3.
In this paper we introduce a simple framework which provides a basis for estimating parameters and testing statistical hypotheses in complex models. The only assumption that is made in the model describing the process under study, is that the deviations of the observations from the model have a multivariate normal distribution. The application of the statistical techniques presented in this paper may have considerable utility in the analysis of a wide variety of complex biological and epidemiological models. To our knowledge, the model and methods described here have not previously been published in the area of theoretical immunology.  相似文献   

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Distance matrices obtained from allozyme studies on tilapiine fish are analysed by a multivarite approach. A hierarchical clustering procedure facilitated comparison with tree representations. A map-like representation provided information additional to the tree representation. The current belief that Sarotherodon is closer to Oreochromis than to Tilapia is strengthened. But while it may be the link between these genera at the species level, it is not entirely distinct from Oreochromis at the molecular level. Further, Sarotherodon and Oreochromis species may have arisen from Tilapia in several speciation events. Some of the species interrelations agreed with inferences from morphological data, and disagreed with those from a consensus maximum parsimony (MP) tree. It is suggested that both Chromidotilapia guntheri and Tylochromis jentinki are ancestral to diVerent sub-groups of Tilapia , so that inferences from morphological studies and the consensus MP method are both partially correct. The graphical representation also suggests that the Nile tilapia strains in Asia may be derived from Egypt rather than from Ghana. It is advantageous to use the map-like and tree representations together for maximum visual informativeness and inference from the data.  相似文献   

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种群趋势指数的方差近似估计式及其应用   总被引:2,自引:0,他引:2  
根据吴惠龙等(1986)发表的稻纵卷叶螟 Cnaphalocrocis medinalis 的生命表及 Watt 种群趋势指数数学模型,在delta-方法的基础上,本文提出了一种种群趋势指数方差的近似估计法,并应用于评价稻螟赤眼蜂Trichogramma japonicum Ashmead 及化学杀虫剂(甲六粉)对稻纵卷叶螟的控制作用。根据中心极限定律,当样本足够大时,种群趋势指数近似于正态分布。根据近似方差估计量以及 Z-检验方法,取得以下结论:放蜂区明显优于对照区,因其种群趋势指数取值较小,相应的 P 值为 0.0111,该区也明显优于化学杀虫剂处理区,相应的 P 值为 0.0036。杀虫剂处理区差于对照区,因其种群趋势指数值较大(0.3035),但这种差异并未达到显著水平,P 值为 0.2236。虽然本文的结论近似于吴惠龙等(1986)单纯依据种群趋势指数所得到的结果,但本文的结论更具统计意义,更加可靠。  相似文献   

10.

Background

Although Daphnia is increasingly recognized as a model for ecological genomics and biomedical research, there is, as of yet, no high-resolution genetic map for the genus. Such a map would provide an important tool for mapping phenotypes and assembling the genome. Here we estimate the genome size of Daphnia magna and describe the construction of an SNP array based linkage map. We then test the suitability of the map for life history and behavioural trait mapping. The two parent genotypes used to produce the map derived from D. magna populations with and without fish predation, respectively and are therefore expected to show divergent behaviour and life-histories.

Results

Using flow cytometry we estimated the genome size of D. magna to be about 238 mb. We developed an SNP array tailored to type SNPs in a D. magna F2 panel and used it to construct a D. magna linkage map, which included 1,324 informative markers. The map produced ten linkage groups ranging from 108.9 to 203.6 cM, with an average distance between markers of 1.13 cM and a total map length of 1,483.6 cM (Kosambi corrected). The physical length per cM is estimated to be 160 kb. Mapping infertility genes, life history traits and behavioural traits on this map revealed several significant QTL peaks and showed a complex pattern of underlying genetics, with different traits showing strongly different genetic architectures.

Conclusions

The new linkage map of D. magna constructed here allowed us to characterize genetic differences among parent genotypes from populations with ecological differences. The QTL effect plots are partially consistent with our expectation of local adaptation under contrasting predation regimes. Furthermore, the new genetic map will be an important tool for the Daphnia research community and will contribute to the physical map of the D. magna genome project and the further mapping of phenotypic traits. The clones used to produce the linkage map are maintained in a stock collection and can be used for mapping QTLs of traits that show variance among the F2 clones.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1033) contains supplementary material, which is available to authorized users.  相似文献   

11.
Shi SP  Qiu JD  Sun XY  Suo SB  Huang SY  Liang RP 《PloS one》2012,7(6):e38772
Protein methylation is predominantly found on lysine and arginine residues, and carries many important biological functions, including gene regulation and signal transduction. Given their important involvement in gene expression, protein methylation and their regulatory enzymes are implicated in a variety of human disease states such as cancer, coronary heart disease and neurodegenerative disorders. Thus, identification of methylation sites can be very helpful for the drug designs of various related diseases. In this study, we developed a method called PMeS to improve the prediction of protein methylation sites based on an enhanced feature encoding scheme and support vector machine. The enhanced feature encoding scheme was composed of the sparse property coding, normalized van der Waals volume, position weight amino acid composition and accessible surface area. The PMeS achieved a promising performance with a sensitivity of 92.45%, a specificity of 93.18%, an accuracy of 92.82% and a Matthew's correlation coefficient of 85.69% for arginine as well as a sensitivity of 84.38%, a specificity of 93.94%, an accuracy of 89.16% and a Matthew's correlation coefficient of 78.68% for lysine in 10-fold cross validation. Compared with other existing methods, the PMeS provides better predictive performance and greater robustness. It can be anticipated that the PMeS might be useful to guide future experiments needed to identify potential methylation sites in proteins of interest. The online service is available at http://bioinfo.ncu.edu.cn/inquiries_PMeS.aspx.  相似文献   

12.
Park  Jonghyuk  Baek  Nakhoon  Kim  Sung-Ho 《Cluster computing》2016,19(4):1879-1884
Cluster Computing - Nowadays, touchable displays are widely used in most embedded systems, including mobile phones and other hand-held devices. Although interactive user interfaces are intuitively...  相似文献   

13.
DNAs of all inbred mouse strains contain multiple copies (18 to 28 copies per haploid mouse genome) of endogenous xenotropic murine leukemia virus-related sequences detectable by Southern analysis with a xenotropic murine leukemia virus env gene-specific probe. After PvuII digestion, we identified a subset of xenotropic murine leukemia virus-related sequences that are well resolved by agarose gel electrophoresis and can be mapped to specific chromosomes by using recombinant inbred mouse strains. Interestingly, three of six xenotropic proviral loci that we mapped were integrated near genes encoding mouse lymphocyte antigens (Ly-m22, chromosome 1; Ly-m6, chromosome 2; and Ly-m10, chromosome 19) and a fourth xenotropic proviral locus mapped near a gene on chromosome 4 that has a major influence on xenotropic virus cell surface antigen levels. These studies indicate that xenotropic proviral loci are located on many different mouse chromosomes and may be useful markers for molecularly cloning and characterizing regions of the mouse genome important in lymphocyte development.  相似文献   

14.
Deciphering the understanding of T cell epitopes is critical for vaccine development. As recognition of specific peptides bound to Major histocompatibility complex (MHC) class I molecules, cytotoxic T cells are activated. This is the major step to initiate of immune system response. Knowledge of the MHC specificity will enlighten the way of diagnosis, treatment of pathogens as well as peptide vaccine development. So far, a number of methods have been developed to predict MHC/peptide binding. In this article, a novel feature amino acid encoding scheme is proposed to predict MHC/peptide complexes. In the proposed method, we have combined orthonormal encoding (OE) and Taylor’s Venn-diagram, and have used Linear support vector machines as the classifier in the tests. We also have compared our method to current feature encoding scheme techniques. The tests have been carried out on comparatively large Human leukocyte antigen (HLA)-A and HLA-B allele peptide three binding datasets extracted from the Immune epitope database and analysis resource. On three datasets experimented, the IC50 cutoff a criteria is used to select the binders and non-binders peptides. Experimental results show that our amino acid encoding scheme leads to better classification performance than other amino acid encoding schemes on a standalone classifier.  相似文献   

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Zhaoping L  Zhe L 《PloS one》2012,7(6):e36223
From a computational theory of V1, we formulate an optimization problem to investigate neural properties in the primary visual cortex (V1) from human reaction times (RTs) in visual search. The theory is the V1 saliency hypothesis that the bottom-up saliency of any visual location is represented by the highest V1 response to it relative to the background responses. The neural properties probed are those associated with the less known V1 neurons tuned simultaneously or conjunctively in two feature dimensions. The visual search is to find a target bar unique in color (C), orientation (O), motion direction (M), or redundantly in combinations of these features (e.g., CO, MO, or CM) among uniform background bars. A feature singleton target is salient because its evoked V1 response largely escapes the iso-feature suppression on responses to the background bars. The responses of the conjunctively tuned cells are manifested in the shortening of the RT for a redundant feature target (e.g., a CO target) from that predicted by a race between the RTs for the two corresponding single feature targets (e.g., C and O targets). Our investigation enables the following testable predictions. Contextual suppression on the response of a CO-tuned or MO-tuned conjunctive cell is weaker when the contextual inputs differ from the direct inputs in both feature dimensions, rather than just one. Additionally, CO-tuned cells and MO-tuned cells are often more active than the single feature tuned cells in response to the redundant feature targets, and this occurs more frequently for the MO-tuned cells such that the MO-tuned cells are no less likely than either the M-tuned or O-tuned neurons to be the most responsive neuron to dictate saliency for an MO target.  相似文献   

17.
The feasibility of reliably estimating percent cover of coral reef benthos by video techniques is examined. Video belt transects were recorded within study areas on Davies and John Brewer Reefs in the central Great Barrier Reef during September 1988. Two years later in September 1990, the study area at Davies Reef was resampled concurrently by video and line intercept transects. Percent cover data of major coral growth forms and non-biotic physionomic attributes were extracted from video footage by scoring the identity of items located at even or random spaced points along the transect. A cost-benefit analysis which compared increases in precision with increases in sampling effort suggested that the optimum regime for analyzing 200 m long video transects was five subsamples of 110 random points or one sample of 550. This regime resolved both spatial variability at large and smaller spatial scales (between study areas and among transects) and temporal change (within a single study area over a two year period) for total live coral and individual growth forms. The strengths of the technique lie in its cost-savings in filed expenses, and in the production of a permanent visual record. The limitations of the technique lie in reduced taxonomic resolution when compared with hands on field techniques. The results suggest that for broad taxonomic categories of coral reef benthos reliable estimates of relative abundance can be obtained by video techniques.  相似文献   

18.
It is shown that, when irradiated in the visible, ethidium bromide (EB) engages in direct photochemistry with its DNA binding site. At the photochemical end point, an average of one single-strand break is produced per bound EB molecule in a reaction which also bleaches the dye chromophore. Using high-resolution electrophoresis, we have mapped the distribution of EB photocleavage sites on DNA, at one-base resolution. It is argued that because the photocleavage is stoichiometric, the resulting pattern is similar to, if not identical with, the local distribution of EB binding affinity. When interpreted in the context of the extensive thermodynamic and structural data which are available for EB, a binding distribution of that kind can be used to infer details of DNA structure variation within the underlying helix. As a first application of the method, we have used EB to probe the structure of a 265 bp fragment of DNA, which had been described as being bent as the result of a periodic array of oligo(A) segments [Kitchin et al. (1986) J. Biol. Chem. 261, 11302]. The EB mapping data provide evidence that the oligo(A) elements in this fragment assume a local secondary structure which is different than that assumed by isolated ApA nearest neighbors and that the ends of the oligo(A) elements comprise a junctional domain with EB binding properties which differ from those of the oligo(A) element or of random-sequence DNA.  相似文献   

19.
Body size is an essential variable in many behavioural and physiological studies. Previous methods for body size estimation present two conflicting drawbacks. They either (1) consider variation in only one dimension through linear measurements or (2) they are time and resource consuming, hard to apply in field conditions and/or stressful to the animal. We present a method for estimating body size, an ellipsoid approximation, which requires simple linear measurements and incorporates variation in three dimensions. The method is tested on two species of teleost fish and one species of insect. The amount of variance in mass explained by the proposed method exceeds that of previous reported methods, including the most accurate ones, that usually require expensive digitising procedures and/or stressful handling.  相似文献   

20.
Body size is an essential variable in many behavioural and physiological studies. Previous methods for body size estimation present two conflicting drawbacks. They either (1) consider variation in only one dimension through linear measurements or (2) they are time and resource consuming, hard to apply in field conditions and/or stressful to the animal. We present a method for estimating body size, an ellipsoid approximation, which requires simple linear measurements and incorporates variation in three dimensions. The method is tested on two species of teleost fish and one species of insect. The amount of variance in mass explained by the proposed method exceeds that of previous reported methods, including the most accurate ones, that usually require expensive digitising procedures and/or stressful handling.  相似文献   

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