空间独立成分分析实现fMRI信号的盲分离

独立成分分析（ICA）在功能核磁共振成像（fMRI)技术中的应用是近年来人们关注的一个热点。简要介绍了空间独立成分分析（SICA）的模型和方法,将fMRI信号分析看作是一种盲源分离问题,用快速算法实现fMRI信号的盲源分离。对fMRI信号的研究大多是在假定已知事件相关时间过程曲线的情况下,利用相关性分析得到脑的激活区域。在不清楚有哪几种因素对fMRI信号有贡献、也不清楚其时间过程曲线的情况下,用SICA可以对fMRI信号进行盲源分离,提取不同独立成分得到任务相关成分、头动成分、瞬时任务相关成分、噪声干扰、以及其它产生fMRI信号的多种源信号。     

Smiss, stoichiometric matrix inversion for steady state metabolic networks.

A program is described for the reduction of the stoichiometric matrices associated with steady state metabolic networks. The program generates a set of independent and dependent reactions and gives the dependent reactions as functions of the independent reactions. The program can also be used to generate all possible alternative sets of independent reactions.     

Application of the isobologram technique for the analysis of combined effects with respect to additivity as well as independence

Combined actions of two substances with similar effects are frequently expressed by pairs of doses that produce a fixed response, usually 50%, in so-called isobolograms (ED50 isobolograms). In addition to the dose scales in such graphs we propose the addition of effect scales, where possible, to indicate the effect at certain doses, e.g., the ED30. We further propose to construct isoboles for expected independent interaction, in addition to the additivity line, for which purpose a simple procedure is delineated. In practice, an independent isobole for 50% effect passes through the point formed by the ED30s of A and of B in ED50 isobolograms. Thus, the ED30s constitute the "zenith" of an independent isobole in ED50 isobolograms. It is shown that theoretical independent isoboles can either represent additive, overadditive, or underadditive interactions, depending on the steepness of the dose-response curves of the components. Hence, drugs with shallow dose-response curves exhibit overadditive independent effects, compounds with exponentially steep curves show additive independent interactions. Substances with very steep dose-response curves, producing lethal effects, exhibited marked underadditive effects which could be ascribed largely to an independent mechanism of action of the components. Hence, the inclusion of independent isoboles into conventional isobolograms provides new insights into the mechanisms of interactions and into the actions of the components. Interactions can thus be characterized better and more completely, and misinterpretations appear less likely than with conventional isoboles.     

均衡独立样本设计的研究

均衡独立样本设计是一种把独立样本设计与差异显著性检验相结合的试验设计．它基本上可以保证参试的优劣个体在所分样本（或组）间的分布相对均匀一致,使所分样本既具有独立性又具有均衡性,以增强对处理效果反应的灵敏度,提高试验的准确度．     

新的独立成分分析算法实现功能磁共振成像信号的盲分离

采用独立成分分析(independent component analysis,ICA)的一种新的牛顿型算法来提取功能磁共振成像(functional magnetic rasonance imaging,fMRI)信号中的各种独立成分(包括与实验设计相关的成分以及各种噪声)。与fastICA相比,该算法减少了运算量,提高了运算速度,而且能够很好地分离出各个独立成分。结果表明该算法是一种有效的fMRI信号分析手段。     

Analysis of Survival Data with Two Dependent Competing Risks

Here we consider a competing risks model where the two risks of interest are not independent. The dependence is due to the additive effect of an independent contaminating risk on two initially independent risks. The problem is identifiable when the three risks fllow independent exponential distributions and also when the two initial risks follow proportional hazards model. Procedures are suggested for estimation and testing hypotheses regarding the parameters of the three exponentials in the first can and the constant of proportionality in the second case, when the information available consists of the times to death and the causes of death of the individuals.     

Comparison of methods for clustering independent EEG components in healthy subjects and patients with postconcussion syndrome after traumatic brain injury

The efficiencies of three clustering methods for independent components of 19-channel baseline EEG in location of pathological cerebral activity sources were compared. The samples comprised 518 healthy subjects and 87 patients with postconcussion syndrome after traumatic brain injury (TBI). Clustering of independent component topographies, the spatial coordinates of equivalent dipole sources corresponding to independent component topographies, and locations of the maximums of the equivalent source current density calculated by standardized low resolution electromagnetic tomography (sLORETA) were compared. A comparison of the power spectra of independent components showed a significant increase in the EEG power in the Δ, θ, and α bands for sources located in the frontal and temporal lobes of TBI patients compared to healthy subjects. The method of clustering of independent component topographies proved to be the most sensitive of the methods compared.     

选择回归方程自变量的条件数法及其在RK手术中的应用

选择合适的自变量是确定线性回归模型的首要问题,本文以消除自变量之间的复共线性为目标,介绍了一种选择回归方程自变量的条件数法,并在ＲＫ手术的结果预测问题中采用了这一方法。     

Kinetic time constants independent of previous single-channel activity suggest Markov gating for a large conductance Ca-activated K channel

Models for the gating of ion channels usually assume that the rate constants for leaving any given kinetic state are independent of previous channel activity. Although such discrete Markov models have been successful in describing channel gating, there is little direct evidence for the Markov assumption of time-invariant rate constants for constant conditions. This paper tests the Markov assumption by determining whether the single-channel kinetics of the large conductance Ca-activated K channel in cultured rat skeletal muscle are independent of previous single-channel activity. The experimental approach is to examine dwell-time distributions conditional on adjacent interval durations. The time constants of the exponential components describing the distributions are found to be independent of adjacent interval duration, and hence, previous channel activity. In contrast, the areas of the different components can change. Since the observed time constants are a function of the underlying rate constants for transitions among the kinetic states, the observation of time constants independent of previous channel activity suggests that the rate constants are also independent of previous channel activity. Thus, the channel kinetics are consistent with Markov gating. An observed dependent (inverse) relationship between durations of adjacent open and shut intervals together with Markov gating indicates that there are two or more independent transition pathways connecting open and shut states. Finally, no evidence is found to suggest that gating is not at thermodynamic equilibrium: the inverse relationship was independent of the time direction of analysis.     

On the equivalence of meta-analysis using literature and using individual patient data

When data come from several independent studies for the purpose of estimating treatment control differences, meta-analysis can be carried out either on the best linear unbiased estimators computed from each study or on the pooled individual patient data modelled as a two-way model without interaction, where the two factors represent the different studies and the different treatments. Assuming that observations within and between studies are independent having a common variance, Olkin and Sampson (1998) have obtained the surprising result that the two meta-analytic procedures are equivalent, i.e., they both produce the same estimator. In this article, the same equivalence is established for the two-way fixed-effects model without interaction with the only assumption that the observations across studies be independent. A consequence of the equivalence result is that, regardless of the covariance structure, it is possible to get an explicit representation for the best linear unbiased estimator of any vector of treatment contrasts in a two-way fixed-effects model without interaction as long as the studies are independent. Another interesting consequence is that, for the purpose of best linear unbiased estimation, an unbalanced two-way fixed-effects model without interaction can be treated as several independent unbalanced one-way models, regardless of the covariance structure, when the studies are independent.     

A new approach to the study of sequence-dependent properties of polynucleotides

A sequence-dependent properly of any long polynucleotide can be related to the properties of a limited number of other polynucleotides. The properties of the constituent sequence subunits need not be individually known. Only the properties of a set of linearly independent sequence combinations in polymers need be known. The number of independent sequences depends on the number of neighboring bases (or base pairs) contributing to the property and on the number of different bases (or base pairs) allowed. General formulae are derived. If only nearest neighbors contribute to a property, there are 13 linearly independent single-strand sequences with four different bases and there are 8 linearly independent double-strand sequences with two different base pairs. The study of independent sequences in polymers should be especially useful with double-stranded polynucleotides. It should be possible by this polymer approach to estimate nearest-neighbor frequencies from the circular dichroism of double strands and also to investigate the relation between solution conformation and double-strand sequence.     

The effects of isoproterenol, UDCG 115, and caffeine on the heart related to excitation-contraction coupling in heart muscle

A myothermal technique was used to measure initial heat and tension independent heat from isometrically contracting papillary muscles taken from the right ventricle of rabbits. Tension independent heat produced by the muscle at Lo was isolated with a 2,3-butanedione monoxime (diacetyl monoxime)--hyperosmotic Krebs solution. The effects of the inotropic drugs isoproterenol (1 X 10(-7) M), UDCG 115 (2 X 10(-4) M), and caffeine (2 X 10(-3) M) on heat and mechanical output were measured. We tested the hypothesis that these drugs alter peak twitch tension by increasing the total amount of Ca2+ cycled during the twitch, assuming that net tension independent heat is proportional to total Ca2+ cycled. The hypothesis was rejected for each drug as the positive inotropic effects of isoproterenol and UDCG 115 on twitch tension were not accompanied by increases in net tension independent heat. Net tension independent heat was actually depressed by UDCG 115. The negative inotropic effect of caffeine on twitch tension was accompanied by an increase in tension independent heat at times between the end of mechanical relaxation and the next stimulus. Possible mechanisms to account for these results are discussed.     

Gender and age differences in basic ADL ability on the elderly: comparison between the independent and the dependent elderly

The purpose of this study was to investigate the ADL ability characteristics of the elderly by comparing the characteristics to achieve basic activities between the independent and institutionalized dependent elderly from the viewpoints of gender and age differences. The subjects were 697 Japanese dependent elderly living at welfare institutions for the aged, and 482 independent elderly living at home. Seventy-four activities were selected from nine ADL domains. The survey for the independent elderly was conducted in health or culture education classes, and for the elderly without these classes, a general delivery survey was conducted. The independent elderly provided their own data. The survey for the dependent elderly was conducted in welfare institutions and the staff working at the subjects' institutions responded. In two-way ANOVA of rates of items, significant gender differences were found in some changing and holding posture activities in the independent elderly group, and in activities using upper extremities in the dependent elderly group. ADL ability in the independent elderly group significantly decreases with aging, but this trend is unclear in the dependent elderly group. In the independent elderly group, indications of a decrease appear in activities with lower limbs from the 70s, and appear in the most of basic activities from the 80s. Furthermore, differences in achievement levels of each activity with aging were found in both elderly groups. These findings may suggest that there are remarkable individual differences in ADL ability of the elderly with aging.     

痛风性膝关节炎的关节镜诊疗价值分析

目的：探讨膝痛风性关节炎的关节镜治疗的临床疗效。方法：选取我院2006年至2009年共35例单膝痛风性关节炎患者,’喀随机分为2组：A组22例,给予药物治疗,同时行关节镜下检查及清理术;B组13例,仅给予药物治疗。观察比较两组患者膝关节Lysholm评分、疼痛VAS评分,关节活动度ROM改善情况。结果：关节镜治疗组22例病例中无关节镜手术并发症发生,关节镜治疗组在Lysholm、VAS评分和关节活动度ROM方面明显优于药物治疗组。结论：膝痛风性关节炎关节镜下有较显著的特点,膝关节镜下清理术治疗膝痛风性关节炎具有良好疗效,为药物治疗膝痛风性关节炎提供了良好的辅助治疗方法。     

Analysis of mammary tumors for cytochemical evidence of endogenous mammary peroxidase.

The purpose of this study was to determine whether or not endogenous mammary peroxidase can serve as a cytochemical marker to distinguish ovarian hormone-dependent from ovarian hormone independent mammary tumors. Spontaneous mammary tumors arising in virgin C3H and GR mice (hormone independent tumors) and hormone-dependent mammary tumors arising during pregnancy in GR mice were examined. None of these tumors contained mammary peroxidase. Mammary tumors induced in Sprague-Dawley rats with methylnitrousourea (MNU) and dimethylbenzanthracene (DMBA) were also examined. These tumors included hormone-dependent and hormone independent ones. Several of the DMBA-induced hormone-dependent tumors contained a few peroxidase-positive cells, but the hormone independent tumors were negative. All of the MNU-induced tumors examined were negative for mammary peroxidase. Twenty human breast tumors (malignant and non-malignant) removed from women at surgery, were also negative for mammary peroxidase. Our results indicate that endogenous mammary peroxidase cannot be used to distinguish hormone-dependent from hormone independent mammary tumors.     

Linear independence of pairwise comparisons of DNA microarray data

MOTIVATION: For DNA microarrays, the gain in certainty by performing multiple experimental repeats is offset by the high cost of each experiment. In a typical experiment, two independent measurements (that is, data from two separate arrays) are combined to yield a single comparative index per gene. Thus, although one uses 2n arrays and performs 2n independent measurements, one obtains only n comparative measurements. We addressed the question: how many of the potential n2 comparisons derivable from such data are actually independent, and what effect do these additional comparisons have on the false positive rate. RESULTS: We show there are precisely 2n - 1 independent comparisons available from among the n2 possibilities. Applying these additional n - 1 independent comparisons to experimental and simulated data reduced the false positive rate by as much as 10-fold, with excellent agreement between experimental and theoretical false positive rates.     

Exploring simple independent action in multifactor tables of proportions

The problem of assessing synergistic or antagonistic departure from simple independent action in multifactor tables of proportions is discussed. A generalized linear model is employed in which additivity corresponds to simple independent action. Data-analytic strategies are proposed for exploring departures from simple independent action in various extensions of the 2 X 2 table of proportions. This methodology is illustrated with a series of models fitted to cellular differentiation and murine toxicity data.     

The Influences of Group and Independent General Practice on Patient Care: A Comparative Study in Ontario

When the practices of four general practitioners, members of multispecialist-general practitioner salaried groups (clinic doctors) were compared with those of four independent general practitioners (solo practitioners), it was noted that: group practice patients had more office laboratory investigation and greater in-hospital consultation and referral. On the other hand, independent practitioners'' patients seemed to receive more personal attention from the doctor, a fuller explanation of diagnosis and treatment during office hours, more drug samples and more laboratory investigation in hospital.Group and independent practices are similar with respect to the rate of follow-up visits, the volume of preventive medicine, the number of radiographs and special procedures, the total number of drugs ordered, and the in-hospital formal written consultation rate and office consultation rate.The similarities between two types of practice may be a result of the interaction of group and independent practice in the same community.It is concluded that the team approach to medical care is not incompatible with independent practice.