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1.
利用重合度理论中的连续性定理研究了时标下具Hassell-Varley型功能性反应的捕食者-食饵系统的周期性,得到周期解存在的充分条件,所得结果推广了已有文献中的相关结论.  相似文献   

2.
讨论一类具有脉冲和功能反应的两种群扩散时滞的竞争系统,利用重合度的理论得到了系统存在正周期解的充分条件,进而改进了现有的一些结果.  相似文献   

3.
In this paper we are concerned with test procedures for umbrella alternatives in the k-sample location problem. Distribution-free tests are considered for both cases where the peak of the umbrella is known or unknown. Comparative results of a Monte Carlo power study are presented.  相似文献   

4.
利用重合度理论中的延拓定理,讨论了捕食者具有阶段结构和比率型功能性反应的捕食模型的正周期解的存在性,得到了保证周期解存在的充分条件,推广了已知的相关结果.  相似文献   

5.
This paper deals with the problem of tele-monitoring EEG signals. In EEG tele-monitoring system, the integral step is to compress the signals in computationally efficient manner so that they can be transmitted over a limited bandwidth. In such a situation a Compressed Sensing (CS) framework for compressing and recovering the signals is the most viable approach. Previously the well known synthesis prior formulation is used for reconstruction. For the first time in this work, we show that the lesser known analysis prior formulation is a more appropriate way to frame the reconstruction problem. We show that our method yields better results than the previous synthesis prior formulation.  相似文献   

6.
具有时滞和反馈控制的Logistic增长模型的正周期解   总被引:9,自引:1,他引:8  
首次研究同时具有状态依赖时滞和连续时滞的反馈控制Logistic增长模型,利用重合度理论研究其正周期解的存在性问题,得到了该系统周期正解存在的充分性条件,同时通过构造适当地Lyapunov泛函得到保证该系统(在适当限制下)存在全局稳定周期解的充分性条件,得到一些新结果,所得结果推广和改进了相关文献的主要结果。  相似文献   

7.
Y形接头延伸法(Y-shaped adaptor dependent extension,YADE)是一种扩增已知DNA片段相邻序列的方法,但其效率常受到已知序列周围酶切位点数目的限制。在Y形接头延伸中采用由多种酶切和连接产生的DNA作模板,大大提高了该方法扩增相邻序列的效率,实现了相邻序列的连续扩增。利用该方法通过2轮连续的扩增从7种酶切连接产物中成功地获得了1个棉花小GTP酶基因(GhRacB)的2228bp上游序列。结果表明,多模板Y形接头延伸法是一种从复杂基因组中扩增相邻序列的有用方法。  相似文献   

8.
A familial mutation in SRY, the gene coding for the testis-determining factor TDF, was identified in an XY female with gonadal dysgenesis, her father, her two brothers and her uncle. The mutation consists of a T to C transition in the region of the SRY gene coding for a protein motif known as the high mobility group (HMG) box, a protein domain known to confer DNA-binding specificity on the SRY protein. This point mutation results in the substitution, at amino acid position 109, of a serine residue for phenylalanine, a conserved aromatic residue in almost all HMG box motifs known. This F109S mutation was not found in 176 male controls. When recombinant wildtype SRY and SRYF109S mutant protein were tested in vitro for binding to the target site AAC AAAG, no differences in DNA-binding activity were observed. These results imply that the F109S mutation either is a rare neutral sequence variant, or produces an SRY protein with slightly altered in vivo activity, the resulting sex phenotype depending on the genetic back-ground or environmental factors.This paper is dedicated by G. S. to Professor Ulrich Wolf on the occasion of his 60th birthday  相似文献   

9.
Several non iterative tests for the equality of two correlated means with missing data on both responses are compared by means of Monte Carlo studies. The main results are that a test due to LIN and STIVERS (1974) is to be preferred when the number of complete pairs is large, a WELCH type statistic with degrees of freedom modified in this paper when the correlation between the two responses is known to be low, and one of four suggested, one in this paper, maximum likelihood based tests when the number of complete pairs is small and there is no large variance inequality believed to exist.  相似文献   

10.
Lee AJ  Lin MC  Hsu CM 《Bio Systems》2011,103(3):392-399
Many methods have been proposed for mining protein complexes from a protein-protein interaction network; however, most of them focus on unweighted networks and cannot find overlapping protein complexes. Since one protein may serve different roles within different functional groups, mining overlapping protein complexes in a weighted protein-protein interaction network has attracted more and more attention recently. In this paper, we propose an effective method, called MDOS (Mining Dense Overlapping Subgraphs), for mining dense overlapping protein complexes (subgraphs) in a weighted protein-protein interaction network. The proposed method can integrate the information about known complexes into a weighted protein-protein interaction network to improve the mining results. The experiment results show that our method mines more known complexes and has higher sensitivity and accuracy than the CODENSE and MCL methods.  相似文献   

11.
Di/oligomerization of G-protein coupled receptors (GPCRs) is well established, however very little is known regarding the interaction details. Current paper presents results of molecular dynamics simulations of theoretical model of rhodopsin tetramer with transducine (Gt) in lipid bilayer. Ligand-protein and receptor-receptor interactions have been proposed.  相似文献   

12.
In this paper, a new immune genetic algorithm for motif discovery is proposed. The algorithm adopts concentration regulation mechanism to maintain the population diversity and vaccine mechanism to inhibit degeneracy during evolution. Experimental results have demonstrated the method's capacity to find known motifs in relatively long promoter sequences and multiple motifs within a single run.  相似文献   

13.
整体原位杂交(Whole-mount in situ hybridization)用于基因表达定位和表达分布模式的研究,已经成为一种非常重要的手段。PCR方法进行探针标记,可以获得特异性高,片断大小可变的探针。采用DIG标记,检测已知基因noggin在爪蟾胚胎时空分布,所得结果与文献报道一致,表明PCR方法获得的DNA探针在一定的条件下可以用于爪蟾胚胎整体原位杂交。  相似文献   

14.
目的利用已有的研究结果和数据,采用多目标评价方法建立乳腺癌易感基因评价模型,对与已知乳腺癌基因关系密切的其它基因进行分析和排序,并给出结果的网络表达模式。方法通过分析已有的文献,并利用有关的基因数据库和已有文献中的数据,提炼出乳腺癌易感基因的多目标评价体系,构建基于加权和法的乳腺癌易感基因评价模型,并利用Cytoscape软件进行评价结果计算和评价结果的网络模式表达。结果利用多目标模型所得到的评价结果,与已有的研究结果一致。其中,乳腺癌易感基因TopBP1排名第二,已知乳腺癌候选易感基因HMMR排名第六。结论文章提出的多目标评价模型能够准确评价被选基因与乳腺癌易感性之间的关系,所提出的评价方法与相关软件结合使用,将成为癌症易感基因研究方面有效的分析方法和途径。  相似文献   

15.
Whenever the calendar age of the studied fetal material is not known we are bound to reconstruct it by replacing it with the developmental age. In this paper some common developmental standards used in the determination of fetal age are reviewed. The standards, as found in the relevant literature, are tested against a control group for their accuracy in predicting fetal age. The results indicate considerable discrepancy among the various standards. Further, the developmental ages defined by these standards often differ considerably from the known menstrual age. My own attempt to present a more reliable set of developmental standards is based on the analysis of three morphological features commonly used in biological assessment. Body weight, crown-heel length, and crown-rump length are measured in weekly termed groups representing the 20th-42nd weeks of intrauterine life. The accuracy of body weight and crown-heel length in predicting fetal age is tested both within and against a control group. Statistical analysis show no significant differences between the predicted and known fetal ages. These results indicate that body weight and crown-heel length are reliable developmental standards from which fetal age can be defined.  相似文献   

16.
ADHD (attention hyperactivity disorder) is a polygenetic disorder with various candidate genes. At this time, more than thirty dopaminergic, noradrenergic, serotonergic and GABA-ergic genes are known. The research of only some candidate genes (DRD4, DAT, DRD5, DBH, 5HTT, HTR1B and SNAP25) brought relatively consistent results confirming the heredity of ADHD syndromes. The results of research of other genes (DRD2, DRD3, MAO, ADR2A, GABA A3, GABA B3) are not clear yet. This paper summarizes the most important genetic data in correlations with biochemical periphery parameters (especially for DBH, HVA, MHPG, serotonin). Hypothetically, certain subgroups of ADHD may be identified by correlation of biochemical characteristics and some candidate genes. The paper discusses some implications for future research. Review.  相似文献   

17.
The Salmonella mutagenicity test (Ames assay) is part of the routine screening battery applied to all new drugs at The Upjohn Company. The purpose of this paper is to report results for 29 compounds. These compounds are very diverse in chemical structure and represent classes of compounds selected because of known biological activity and other reasons. None of the compounds reported here produced an increase in revertant colonies in the Salmonella strains employed (TA98, TA100, TA1535, TA1537 and TA1538) and therefore the Salmonella mutagenicity results with these materials do not suggest potential for mutagenesis or carcinogenesis.  相似文献   

18.
Zenithoptera dragonflies are known for their remarkable bluish colouration on their wings and unique male behaviour of folding and unfolding their wings while perching. However, nothing is known about the optical properties of such colouration and its structural and functional background. In this paper, we aimed to study the relationship between the wing membrane ultrastructure, surface microstructure and colour spectra of male wings in Zenithoptera lanei and test the hypothesis that colouration functions as a signal in territorial fights between males. The results show that the specific wing colouration derives from interference in alternating layers of melanized and unmelanized cuticle in the wing membrane, combined with diffuse scattering in two different layers of wax crystals on the dorsal wing surface, one lower layer of long filaments, and one upper layer of leaf-shaped crystals. The results also show that the thicker wax coverage of the dorsal surface of the wings results in increased brightness and reduced chroma. In the field experiments, we have demonstrated that there is a reduction of aggressive reactions of rivals towards individuals with experimentally reduced amount of blue wing colouration.  相似文献   

19.
The use of ratio and product estimators, using auxiliary information, for estimating the mean of a finite population is well known. The efficiency of ratio estimator or product estimator is high depending on whether the auxiliary character is highly positively or negatively coorelated with the main character of interest. This paper proposes a product-type estimator which is more efficient than the usual ratio and product estimators in practical situations. We consider the case of double sampling from which the single sampling results may easily be derived.  相似文献   

20.
In this paper we present solutions of the master equations for the microtubule length and show that the local probability for rescues or catastrophes can lead to bell-shaped length histograms. Conversely, as already known, non-local probabilities for these events result in exponential length histograms. We also derive master equations for a stabilizing cap and obtain a new boundary condition which provides an explanation of the results obtained in dilution and cutting experiments.  相似文献   

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