红树植物木榄种群高度结构的分形特征

 采用计测等值线分形维数的方法,探讨山口国家级红树林自然保护区内的木榄(Bruguiera gymnorrhiza)种群高度结构的特征。结果表明,木榄种群的高度结构具有分形的特征,其计盒维数介于1.61～1.90之间,信息维数介于1.63～1.84之间,分形维数的高低主要与幼树个体的数量、个体的集聚程度和高度层次结构的复杂程度等密切相关。计盒维数定量描述种群占据垂直空间的能力和程度,而信息维数揭示种群高度层次细节的尺度变化强度和个体高度分布的非均匀性程度。分析表明,等值线法能够有效地表征木榄种群高度结构的分     

Visual discrimination of fractal borders.

The ideas of fractals and fractal dimension are here translated into the realm of visual psychophysics. Borders between two fields of different luminance were used. Because of the finite grain of the visual system, fractal dimension need be defined only within a certain size range. For a fractal dimension of 1.15, the just-detectable difference in fractal dimension was found to be about 0.0085, rising to about 0.015 for a fractal dimension of 1.25. Reducing exposure duration from 1 s to 0.33 s decreases sensitivity to differences in fractal dimension, but there was no gain in increasing the exposure duration. Good visual observers who are naive to the task require some training before reaching optimal performance. The ability to discriminate fractal dimension differs between fractal edges of the same fractal dimension that were generated with differing statistical programs. Even after considerable training, an observer makes 29% errors when asked to distinguish a fractal edge generated with a Gaussian random walk from one with a rectangular random walk. Gaussian random walk fractals can be more easily distinguished from Poissonian and Cauchy ones.     

基于盒维数的心音信号分形特征研究

在传统盒维数的基础上,从尺度变化的角度,提出一种计算心音信号时域波形分形维数的新的二进盒维数算法,并给出了算法思想和估算方法;然后用该方法对正常心音和几种典型的病态心音的分形维数进行计算,并对其分形特征进行了研究．研究结果表明：心音信号具有明显的分形特征,分形维数能够反映心音信号的复杂程度,并且能够明显地区分正常心音和病态心音．     

云贵鹅耳枥种群分布格局的分形特征

应用分形理论中的计盒维数和信息维数探讨了贵阳喀斯特山地贵鹅耳枥种群分布格局的分形特征。结果表明,贵鹅耳枥种群的分布格局具有分形特征,其计盒维数为1．1853－1．7419,信息维数为1．1961－1．7051。集群型的贵鹅耳枥种群的计盒维数和信息维数均比随机型的高。计盒维数定量地反映了贵鹅耳枥种群占据生态空间的能力,信息维数则揭示了该种群格局强度的尺度变化程度和表征了种群个体分布的非均匀性。这两种维数方法都适用于贵鹅耳枥种群分布格局分形特征的定量描述。     

Intradimensional and extradimensional shifts in conditional discrimination

Two groups of pigeons learned a two key conditional discrimination. Color was the conditional stimulus and form the choice stimulus for subjects in one group. Form was the conditional stimulus and color the choice stimulus in the other group. Half the subjects in each group then underwent an intradimensional shift: The conditional stimulus dimension and choice stimulus dimension were unchanged but the correct and incorrect stimulus compounds were reversed. The remaining subjects underwent an extra-dimensional shift in which the conditional stimulus dimension and choice stimulus dimension were reversed. Subjects which experienced an intradimensional shift learned the new conditional discrimination more quickly. It was concluded that subjects followed rules to solve conditional discriminations but also learned the functions of each stimulus dimension.     

天然黄山松种群格局的分形特征——计盒维数与信息维数

采用计盒维数和信息维数对屏南和寿宁不同群落的天然黄山松(Pinus taiwanensis)种群格局的分形特征进行比较分析.结果表明,天然黄山松种群格局具有分形特征,其计盒维数值在1.299 8～1.862 6之间,不同群落的大小次序为Q3>Q1>Q2>Q4>Q7>Q8>Q5>Q6;信息维数值在1.205 7～1.863 7之间,大小次序是Q3>Q1>Q2>Q4>Q8>Q7>Q5>Q6,屏南天然黄山松近纯林黄山松种群的计盒维数和信息维数均高于寿宁混交林,计盒维数定量描述种群占据水平空间的能力和程度,信息维数揭示种群格局强度的尺度变化及个体分布的非均匀程度,分形维数值的高低与群落环境、种群密度、种群在群落中的优势地位、个体的聚集程度及幼树个体数量等相关.黄山松种群格局分形维数随海拔呈现上下波动变化,1 250～1 270 m是更适生的海拔范围.此外,黄山松种群格局的分形特征存在一定的尺度范围,其拐点尺度是分形范围的下限尺度.     

Fractal dimension in human cerebellum measured by magnetic resonance imaging

Fractal dimension has been used to quantify the structures of a wide range of objects in biology and medicine. We measured fractal dimension of human cerebellum (CB) in magnetic resonance images of 24 healthy young subjects (12 men and 12 women). CB images were resampled to a series of image sets with different 3D resolutions. At each resolution, the skeleton of the CB white matter was obtained and the number of pixels belonging to the skeleton was determined. Fractal dimension of the CB skeleton was calculated using the box-counting method. The results indicated that the CB skeleton is a highly fractal structure, with a fractal dimension of 2.57 +/- 0.01. No significant difference in the CB fractal dimension was observed between men and women.     

Determination of the fractal dimension of membrane protein aggregates using fluorescence energy transfer.

It is demonstrated that fluorescence resonance energy transfer may be used to determine the fractal dimension of aggregates of membrane-bound proteins. Theoretical and experimental results are presented for two different experimental designs: energy transfer between proteins and energy transfer from lipids to proteins. For energy transfer between proteins the lattice spacing must be known independently for a fractal dimension to be uniquely determined, and this represents a disadvantage to this experimental design. Results are presented for the calcium ATPase and a fractal dimension of 1.9 is estimated for ATPase aggregates by assuming a lattice spacing of 50 A. Energy transfer from lipids to protein provides a means of estimating the length of the "coast-line" of the aggregate. In this case the fractal dimension is uniquely determined from a log-log plot. An analysis of data for bacteriohodopsin reconstituted in phospholipid vesicles gives a fractal dimension of 1.6. The structural basis of the value for the fractal dimension is discussed for these two systems. These techniques provide a means of assessing the nature of protein-protein interactions in membranous systems.     

The Quasi-Fractal Structure of Fish Brain Neurons

The box-counting method for calculating the fractal dimension (D) with the ImageJ 1.20s software is used as a tool for quantitative analysis of the neuronal morphology in the fish brain. The fractal dimension was determined for several types of neurons in the brain of two teleost species, Pholidapus dybowskii and Oncorhynchus keta. These results were compared with those obtained for some neurons of the human brain. The fractal (fractional) dimension (D), as a quantitative index of filling of two-dimensional space by the black and white image of a cell, is shown to vary from 1.22 to 1.72 depending on the type of neuron. The fractal dimension reaches its maximum in less specialized neurons that carry out a number of different functions. On the other hand, highly specialized neurons display a relatively low fractal dimension. Thus, the fractal dimension serves as a numerical measure of the spatial complexity of the neuron and correlates with the morphofunctional organization of the cell.     

保安湖莲群丛分布格局分形特征的初步研究

应用非线性科学中的分形几何理论,以保安湖扁担塘湖汊中的莲群丛为对象,研究该群丛小尺度水平格局的分形特征。主要应用计盒维数和信息维数公式计算群丛中莲种群和菱种群的个体分布格局的分维值,莲的计盒维数为1.92,信息维数为1.88;菱的计盒维数为1.04,信息维数为1.11.表明在采样区莲的空间占有程度远大于菱,是该时期的优势种,而菱则成为伴生种。莲在各尺度上的分布较均匀。最后讨论了莲的分维值在连续样方上的变化。       

Fractal dimension in aspiration cytology smears of breast and cervical lesions

OBJECTIVE: To standardize the automated measurement of fractal dimension on cytologic smears and compare the fractal dimension of benign and malignant breast cells and cervical lesions on cytologic material to evaluate its role in the discrimination of benign from malignant cells. STUDY DESIGN: We randomly selected fine needle aspiration cytology smears of 42 cases of infiltrating duct carcinoma and 38 cases of fibroadenoma of the breast. Similarly, 16 cervical carcinoma and 20 normal cervical smears were selected for study. Ten cells were selected randomly from each case. Box counting of fractal dimension of malignant and benign cells was achieved with an image cytometer (Leica, Cambridge, England) using Quantimet 600 software (Leica). Then a well-spaced grid with multiple small boxes of a particular pixel length was superimposed on the cell. The dimension of the box was selected as 4, 8 and 16 pixels. With the help of a logical "AND" operation, we counted the number of boxes touching the peripheral margin of the cell nuclei. For each cell, the log-log graph of 1 per box size was plotted against the number of boxes touching the peripheral rim of the cell. The slope of each graph was identified using the least-squares method of regression analysis. RESULTS: The mean fractal dimension of malignant cells was 0.8536 +/- 0.1120 as compared to 0.8403 +/- 0.1115 in benign cell groups. The Mann-Whitney U test showed a significant difference in fractal dimension in these 2 groups (P = .05). The mean fractal dimension of malignant cells from the cervix was 0.8656 +/- 0.1499 as compared to 0.8315 +/- 0.1312 in benign cells. The Mann-Whitney U test showed a significant difference in fractal dimension in these 2 groups (P < .02). CONCLUSION: Fractal dimension may be a helpful adjunctive technique to discriminate between benign and malignant cells.     

北美车前(Plantago Virginica)和车前(P.asiatica)分布格局的分形分析

北美车前 (ＰｌａｎｔａｇｏｖｒｉｇｉｎｉｃａＬ .)是我国东南地区的一种外来杂草 ,该杂草在浙江、江苏、上海、江西等省区有分布 ,多见于田梗路边、住宅四周、抛荒地、公路两侧等人畜出没频繁的地段 ,其种群生长迅速 ,呈现出生态爆发态势 ,是一种典型的生态入侵种。分形理论已被广泛地应用于自然科学、社会科学中的众多领域。在生态学领域 ,应用分形维数能够客观地表达种群的分布式样 ,同时也能反映种群占有空间、资源利用的能力[1～ 6 ] 。本研究以新入侵种北美车前为对象 ,并与我国境内分布较广的杂草车前 (Ｐ .ａｓｉａｔｉｃａ)作比…     

Matrix dimensions bias demographic inferences: implications for comparative plant demography

While the wealth of projection matrices in plant demography permits comparative studies, variation in matrix dimensions complicates interspecific comparisons. Collapsing matrices to a common dimension may facilitate such comparisons but may also bias the inferred demographic parameters. Here we examine how matrix dimension affects inferred demographic elasticities and how different collapsing criteria perform. We analyzed 13 x 13 matrices representing nine plant species, collapsing these matrices (i) into even 7 x 7, 5 x 5, 4 x 4, and 3 x 3 matrices and (ii) into 5 x 5 matrices using different criteria. Stasis and fecundity elasticities increased when matrix dimension was reduced, whereas those of progression and retrogression decreased. We suggest a collapsing criterion that minimizes dissimilarities between the original- and collapsed-matrix elasticities and apply it to 66 plant species to study how life span and growth form influence the relationship between matrix dimension and elasticities. Our analysis demonstrates that (i) projection matrix dimension has significant effects on inferred demographic parameters, (ii) there are better-performing methods than previously suggested for standardizing matrix dimension, and (iii) herbaceous perennial projection matrices are particularly sensitive to changes in matrix dimensionality. For comparative demographic studies, we recommend normalizing matrices to a common dimension by collapsing higher classes and leaving the first few classes unaltered.     

黑土表层土壤颗粒的分形特征

基于第二次全国土壤普查结果,应用土壤颗粒的质量分布计算了36个典型剖面表层土壤颗粒的分形维数值.结果表明:土壤颗粒分形维数值D在2.5831～2.8230,其变异性极弱,且分形维数值随质地变细而增大;土壤机械组成中,砂粒(2～0.02mm)含量、粉粒(0.02～0.002mm)含量与分形维数值均呈显著负相关(P<0.05);粘粒(<0.002mm)含量与土壤分形维数值呈极显著正相关(P<0.01);分形维数值D与土壤中的有机质、全N、全P、全K含量及pH值相关性均不显著.土壤分布的分形维数可以作为反映黑土退化程度的一个综合性定量指标.     

Immobilization of the first dimension in 2D blue native/SDS-PAGE allows the relative quantification of membrane proteomes

In biological membranes many proteins are organized in complexes. The method of choice for the global analysis of the subunits of these complexes is two-dimensional blue native (2D BN)/SDS-PAGE. In the 1st dimension complexes are separated by BN-PAGE, and in the 2nd dimension their subunits are resolved by SDS-PAGE. In the currently available protocols the 1st dimension BN gel lanes get distorted during their transfer to the 2nd dimension separation gels. This leads to low reproducibility and high variation of 2D BN/SDS-gels, rendering them unsuitable for comparative analysis. We have developed a 2D BN/SDS-PAGE protocol where the 1st dimension BN gel is cast on a GelBond PAG film. Immobilization prevents distortion of BN gel lanes, which lowers variation and greatly improves reproducibility of 2D BN/SDS-gels. 2D BN/SDS-PAGE with an immobilized 1st dimension was used for the comparative analysis of the cytoplasmic membrane proteomes of Escherichia coli cells overexpressing a membrane protein and to create a 2D BN/SDS-PAGE reference map of the E. coli cytoplasmic membrane proteome with 143 identified proteins from 165 different protein spots.     

A comparison of intradimensional and extradimensional shift learning in pigeons

In each of three experiments pigeons were trained on a simultaneous discrimination between stimuli that differed in both colour and orientation. For half the birds the colour dimension was relevant and for half orientation was relevant (i.e., differences along that dimension were correlated with reward and nonreward). All birds were then shifted to a second discrimination between new colours and orientations. For half this constituted an intradimensional shift in that the previously relevant dimension remained relevant; for the remainder the previously irrelevant dimension was made relevant (an extradimensional shift). Contrary to the predictions of attentional theory, the two types of shift were learned with equal ease.     

小叶章种群分布格局的分形特征Ⅱ信息维数与关联维数

应用分形理论中的信息维数(Information dimension)和关联维数(Carrelation dimension)研究了三江平原小叶章(Deyeuxia angustifolia)种群分布格局特征。结果表明:信息维数在5~9月分别为1.494、1.709、1.642、1.553、1.625,表明其结构较复杂,格局强度较高。关联维数则为1.662、1.861、1.766、1.750、1.807,说明小叶章个体空间相关程度较高。种内竞争强烈,对空间有较强的占据能力。两个维数的季节动态均自5月至6月达到极大值,而后逐渐下降,至9月略有回升。     

The nonlinear parameters of interference EMG of two day old human newborns

Temporal structure of interference electromyogram (iEMG) was studied in healthy two days old human newborns (n = 76) using the non-linear parameters (correlation dimension, fractal dimension, correlation entropy). It has been found that the non-linear parameters of iEMG were time-dependent because they were decreasing within the first two days of life. Also, these parameters were sensitive to muscle function, because correlation dimension, fractal dimension, and correlation entropy of iEMG in gastrocnemius muscle differed from the other muscles. The non-linear parameters were proven to be independent of the iEMG amplitude. That model of early ontogenesis may be of potential use for investigation of anti-gravitation activity.     

Brain activation associated with ratings of the hedonic component of thermal sensation during whole-body warming and cooling

Thermal sensation has both discriminative and hedonic components. The neural network associated with thermal discrimination has been described, but the representation of the hedonic component of thermal sensation in the brain has yet to be demonstrated. This study measured regional cerebral blood flow (rCBF) with Positron Emission Tomography in human participants during whole-body cooling and warming. Ratings of the hedonic dimension of thermal sensation were correlated with rCBF and compared to brain activation maps of skin and core temperature changes. The hedonic dimension of thermal sensation was represented in a widely distributed network that included somatosensory, limbic, paralimbic, and associative cortices. Changes in rCBF associated with ratings of the hedonic dimension of thermal sensation were contrasted with changes in rCBF associated with skin and core temperature to identify brain regions that were uniquely activated by the hedonic dimension of thermal sensation. The contrast between the correlates of the hedonic dimension of thermal sensation and the correlates of skin and core temperatures identified a region in the posterior part of the mid cingulate cortex (pMCC). The independent relationship between rCBF changes in the pMCC with ratings of the hedonic dimension of thermal sensation may indicate an important role for the pMCC in the integration of temperature-related signals from receptors in the skin and core.