BACKGROUND & AIMS: :A phylogeny of tetrapods is inferred from nearly complete sequences of the nuclear RAG-1 gene sampled across 88 taxa encompassing all major clades, analyzed via parsimony and Bayesian methods. The phylogeny provides support for Lissamphibia, Theria, Lepidosauria, a turtle-archosaur clade, as well as most traditionally accepted groupings. This tree allows simultaneous molecular clock dating for all tetrapod groups using a set of well-corroborated calibrations. Relaxed clock (PLRS) methods, using the amniote = 315 Mya (million years ago) calibration or a set of consistent calibrations, recovers reasonable divergence dates for most groups. However, the analysis systematically underestimates divergence dates within archosaurs. The bird-crocodile split, robustly documented in the fossil record as being around approximately 245 Mya, is estimated at only approximately 190 Mya, and dates for other divergences within archosaurs are similarly underestimated. Archosaurs, and particulary turtles have slow apparent rates possibly confounding rate modeling, and inclusion of calibrations within archosaurs (despite their high deviances) not only improves divergence estimates within archosaurs, but also across other groups. Notably, the monotreme-therian split ( approximately 210 Mya) matches the fossil record; the squamate radiation ( approximately 190 Mya) is younger than suggested by some recent molecular studies and inconsistent with identification of approximately 220 and approximately 165 Myo (million-year-old) fossils as acrodont iguanians and approximately 95 Myo fossils colubroid snakes; the bird-lizard (reptile) split is considerably older than fossil estimates (< or = 285 Mya); and Sphenodon is a remarkable phylogenetic relic, being the sole survivor of a lineage more than a quarter of a billion years old. Comparison with other molecular clock studies of tetrapod divergences suggests that the common practice of enforcing most calibrations as minima, with a single liberal maximal constraint, will systematically overestimate divergence dates. Similarly, saturation of mitochondrial DNA sequences, and the resultant greater compression of basal branches means that using only external deep calibrations will also lead to inflated age estimates within the focal ingroup.

背景与目标： ：四足动物的系统发育是从简约的核RAG-1基因序列中推断出来的，该RAG-1基因在88个分类单元中采样，涵盖所有主要进化枝，通过简约和贝叶斯方法进行了分析。系统发育学为Lissamphibia，Theria，Lepidosauria，乌龟-恐龙进化枝以及大多数传统接受的分类提供了支持。该树允许使用一组经过充分验证的校准同时对所有四足动物组进行分子时钟测年。松散时钟（PLRS）方法使用羊水= 315 Mya（百万年前）校准或一组一致的校准，可以为大多数组恢复合理的发散日期。但是，该分析系统地低估了恐龙内部的发散日期。在化石记录中有据可查的是，鸟类与鳄鱼的分裂大约为245 Mya，据估计仅为大约190 Mya，同样低估了恐龙内其他发散的日期。始祖龙，特别是乌龟的表观速率很慢，可能会混淆速率建模，并且在始祖龙中添加标定值（尽管它们的高度偏差）不仅可以改善始祖龙内的差异估计，而且还可以提高其他群体之间的差异估计。值得注意的是，单极-以太裂（约210米亚）与化石记录相符。鳞状辐射（大约190 Mya）比最近的一些分子研究所建议的要年轻，并且与大约220个和大约165个Myo（百万岁）化石被定为尖牙鬣蜥和大约95个Myo化石类蛇蝎蛇不一致；鸟类-蜥蜴（爬行动物）分裂的年龄比化石估计的年龄大得多（<或= 285 Mya）； Sphenodon是一个非凡的系统发育遗迹，是超过25亿年前的世系的唯一幸存者。与其他有关四脚架发散的分子钟研究的比较表明，在单个自由最大约束的情况下，将大多数标定强制为最小值的惯例会系统地高估发散日期。类似地，线粒体DNA序列的饱和以及基底分支的更大压缩意味着仅使用外部深层校准也会导致焦点人群的年龄估计膨胀。

BACKGROUND & AIMS: :A brain network consisting of two key parietal nodes, the precuneus and the posterior cingulate cortex, has emerged from recent fMRI studies. Though it is anatomically adjacent to and spatially overlaps with the default mode network (DMN), its function has been associated with memory processing, and it has been referred to as the parietal memory network (PMN). Independent component analysis (ICA) is the most common data-driven method used to extract PMN and DMN simultaneously. However, the effects of data preprocessing and parameter determination in ICA on PMN-DMN segregation are completely unknown. Here, we employ three typical algorithms of group ICA to assess how spatial smoothing and model order influence the degree of PMN-DMN segregation. Our findings indicate that PMN and DMN can only be stably separated using a combination of low-level spatial smoothing and high model order across the three ICA algorithms. We thus argue for more considerations on parametric settings for interpreting DMN data.

背景与目标： 最近的功能磁共振成像研究已经形成了一个由两个重要的顶叶节组成的大脑网络，即前神经突和后扣带回皮层。尽管它在解剖上与默认模式网络（DMN）相邻并在空间上重叠，但其功能已与内存处理相关联，并且已被称为顶内存网络（PMN）。独立成分分析（ICA）是用于同时提取PMN和DMN的最常见的数据驱动方法。但是，ICA中的数据预处理和参数确定对PMN-DMN隔离的影响是完全未知的。在这里，我们采用ICA组的三种典型算法来评估空间平滑度和模型阶数如何影响PMN-DMN分离的程度。我们的发现表明，只有结合使用三种ICA算法中的低级空间平滑和高模型阶数，才能稳定地分离PMN和DMN。因此，我们主张对用于解释DMN数据的参数设置进行更多考虑。

BACKGROUND & AIMS: :Recent experimental chemical vapor depositions of silicon at extreme pressures of ~ 50 MPa (~ 500 atm) have been observed to generate remarkably smooth surfaces not predicted by low-pressure deposition models. In this paper, we propose an anti-shadowing mechanism where the collision of particles within the valleys of the surface growth front leads to smoothening. We conduct Monte Carlo simulations to simulate the evolution of film roughness at pressures between 1 and 50 MPa. We observe that surface roughness approaches an asymptotic invariant value that follows power law behavior as a function of pressure. The film thickness at which invariance begins is shown to have a similar power law behavior with respect to pressure. Our simulated results compare favorably with recent experimental observations and provide insight into the fundamental mechanisms underlying film evolution at pressures between one and hundreds of atmospheres.

背景与目标： ：最近观察到的实验性硅化学气相沉积是在〜50 MPa（〜500 atm）的极端压力下产生的，非常光滑的表面是低压沉积模型所无法预测的。在本文中，我们提出了一种防阴影机制，其中表面生长前沿的谷内的粒子碰撞导致平滑。我们进行蒙特卡洛模拟以模拟在1至50 MPa的压力下薄膜粗糙度的演变。我们观察到表面粗糙度接近渐近不变值，该渐近不变值遵循幂律行为作为压力的函数。不变性开始的膜厚度显示出相对于压力具有相似的幂律特性。我们的模拟结果可与最近的实验观察结果相提并论，并提供了对在1个大气压和数百个大气压之间的压力下薄膜演化的基本机理的深入了解。

BACKGROUND & AIMS: :As improvements in cortical surface modeling allowed accurate cortical topology in brain imaging studies, surface-based methods for the analysis of functional magnetic resonance imaging (fMRI) were introduced to overcome the topological deficiency of commonly used volume-based methods. The difference between the two methods is mainly due to the smoothing techniques applied. For practical applications, the surface-based methods need to quantitatively validate the accuracy of localizing activation. In this study, we evaluated the spatial accuracy of activation detected by the volume- and surface-based methods using simulated blood oxygenation level-dependent (BOLD) signals and MRI phantoms focusing on the influence of their smoothing techniques. T1- and T2-weighted phantoms were acquired from BrainWeb () and used to extract cortical surfaces and to generate echo planar imaging (EPI) data. Simulated BOLD signals as the gold standard of activation in our experiment were applied to the surfaces and projected to the volume space with random noise. Three-dimensional isotropic Gaussian kernel smoothing and two-dimensional heat kernel smoothing were applied to the volume- and surface-based methods. Sensitivity and 1-specificity, which are truly and falsely detected activations, and similarity measures, which are spatially and statistically similar for the gold standard and detected activations, were calculated. In the results, the surface-based method showed the sensitivity and similarity scores of about 12% higher than the volume-based method. In conclusion, the surface-based method guarantees better spatial accuracy for the localization of BOLD signal sources within the cortex than the volume-based method.

背景与目标： ：由于皮质表面建模的改进使大脑成像研究中的皮质拓扑结构更加精确，因此引入了基于表面的功能磁共振成像（fMRI）分析方法，以克服常用的基于体积的方法的拓扑缺陷。两种方法之间的差异主要是由于应用了平滑技术。对于实际应用，基于表面的方法需要定量验证定位激活的准确性。在这项研究中，我们评估了基于体积和基于表面的方法使用模拟的血液氧合水平依赖性（BOLD）信号和MRI幻像（重点关注其平滑技术的影响）检测到的激活的空间准确性。从BrainWeb（）获得了T1和T2加权的幻像，并用于提取皮质表面并生成回波平面成像（EPI）数据。在我们的实验中，将模拟的BOLD信号作为激活的金标准，将其应用于表面并投射到具有随机噪声的体积空间中。将三维各向同性高斯核平滑和二维热核平滑应用于基于体积和表面的方法。计算了真实和错误检测到的激活的灵敏度和1特异性，以及金标准品和检测到的激活在空间和统计上相似的相似性度量。在结果中，基于表面的方法显示出比基于体积的方法高约12％的灵敏度和相似性得分。总之，与基于体积的方法相比，基于表面的方法可确保BOLD信号源在皮质内定位的空间精度更高。

BACKGROUND & AIMS: OBJECTIVE:Volume segmentation with concurrent visualization is becoming an increasingly important part of medical diagnostics. This is due to the fact that the immediate visual feedback speeds up evaluation of the segmentation process, hence enhances segmentation quality. Therefore, our aim was to develop a method for volume segmentation and smoothing which achieves interactive performance on standard PCs and is useful in clinical practice (i.e. fast and of high quality). METHODS:Our application is based on seeded region growing and nonlinear isotropic as well as anisotropic diffusion. We use current GPUs (graphics processing units) to speed up the computation of the diffusion process and use hardware-accelerated interactive volume rendering. RESULTS:Using our approach the user can observe the diffusion process in real-time, change parameters interactively and view the result in a high-quality 3D direct volume rendering (DVR). CONCLUSION:The interactive nature of our algorithm and simultaneous visualization improved the usability of our segmentation and smoothing algorithm and proved useful in the clinical workflow. Using our application we were able to speed up the (an)isotropic diffusion process to achieve interactive performance.

背景与目标： 目的：同时进行可视化的体积分割正成为医学诊断中越来越重要的部分。这是由于以下事实：立即的视觉反馈加快了对分割过程的评估，因此提高了分割质量。因此，我们的目标是开发一种用于体积分割和平滑的方法，该方法可在标准PC上实现交互性能，并且可用于临床实践（即快速且高质量）。
方法：我们的应用是基于种子区域生长和非线性各向同性以及各向异性扩散。我们使用当前的GPU（图形处理单元）来加速扩散过程的计算，并使用硬件加速的交互式体绘制。
结果：使用我们的方法，用户可以实时观察扩散过程，以交互方式更改参数，并以高质量3D直接体积渲染（DVR）观看结果。
结论：我们算法的交互性质和同时可视化提高了我们的分割和平滑算法的可用性，并被证明在临床工作流程中很有用。使用我们的应用程序，我们能够加快（各向同性）扩散过程，以实现交互性能。

BACKGROUND & AIMS: :Diffusion Tensor Imaging (DTI) data is characterized by a high noise level. Thus, estimation errors of quantities like anisotropy indices or the main diffusion direction used for fiber tracking are relatively large and may significantly confound the accuracy of DTI in clinical or neuroscience applications. Besides pulse sequence optimization, noise reduction by smoothing the data can be pursued as a complementary approach to increase the accuracy of DTI. Here, we suggest an anisotropic structural adaptive smoothing procedure, which is based on the Propagation-Separation method and preserves the structures seen in DTI and their different sizes and shapes. It is applied to artificial phantom data and a brain scan. We show that this method significantly improves the quality of the estimate of the diffusion tensor, by means of both bias and variance reduction, and hence enables one either to reduce the number of scans or to enhance the input for subsequent analysis such as fiber tracking.

背景与目标： ：扩散张量成像（DTI）数据的特点是高噪声水平。因此，诸如各向异性指数或用于光纤跟踪的主扩散方向之类的量的估计误差相对较大，并且可能会大大混淆DTI在临床或神经科学应用中的准确性。除了脉冲序列优化以外，通过平滑数据来降低噪声可以作为提高DTI精度的一种补充方法。在这里，我们建议一种各向异性的结构自适应平滑方法，该方法基于“传播-分离”方法，并保留了DTI中看到的结构以及它们的不同大小和形状。它适用于人工幻象数据和脑部扫描。我们表明，该方法通过减少偏差和减少方差，显着提高了扩散张量估计的质量，因此使减少扫描次数或增强输入以进行后续分析（如纤维跟踪）的方法得以实现。

BACKGROUND & AIMS: :Two oft-cited drawbacks of kernel density estimators (KDEs) of home range are their sensitivity to the choice of smoothing parameter(s) and their need for independent data. Several simulation studies have been conducted to compare the performance of objective, data-based methods of choosing optimal smoothing parameters in the context of home range and utilization distribution (UD) estimation. Lost in this discussion of choice of smoothing parameters is the general role of smoothing in data analysis, namely, that smoothing serves to increase precision at the cost of increased bias. A primary goal of this paper is to illustrate this bias-variance trade-off by applying KDEs to sampled locations from simulated movement paths. These simulations will also be used to explore the role of autocorrelation in estimating UDs. Autocorrelation can be reduced (1) by increasing study duration (for a fixed sample size) or (2) by decreasing the sampling rate. While the first option will often be reasonable, for a fixed study duration higher sampling rates should always result in improved estimates of space use. Further, KDEs with typical data-based methods of choosing smoothing parameters should provide competitive estimates of space use for fixed study periods unless autocorrelation substantially alters the optimal level of smoothing.

背景与目标： ：经常提到的原始范围内核密度估计器（KDE）的两个缺点是，它们对选择平滑参数的敏感性以及对独立数据的需求。已经进行了一些模拟研究，以比较在家庭范围和利用率分布（UD）估计的情况下选择最佳平滑参数的客观，基于数据的方法的性能。在平滑参数选择的讨论中，丢失的是平滑在数据分析中的一般作用，即，平滑以增加偏差为代价来提高精度。本文的主要目的是通过将KDE应用到来自模拟运动路径的采样位置来说明这种偏差-方差的权衡。这些模拟也将用于探讨自相关在估计UD中的作用。自相关可以通过以下方法降低：（1）通过增加研究持续时间（针对固定样本量）或（2）通过降低采样率来降低。尽管第一种选择通常是合理的，但对于固定的研究持续时间，较高的采样率应始终可以改善对空间使用的估计。此外，除非采用自相关方法可以显着改变最佳平滑度，否则采用典型的基于数据的平滑度选择方法的KDE应当提供固定研究期间空间使用的竞争性估算值。

BACKGROUND & AIMS: :The effect of alkyltrimethylammonium ions on the thermostability of natural and modified DNA duplexes has been investigated. We have shown that the use of tetramethylammonium ions TMA+along with the chemical modification of duplexes allow the fine adjustment of T m and the possibility of obtaining several duplex systems with varied isostabilizedtemperatures, some of which show greater stability than those of natural DNA. This approach could be very useful for DNA sequencing by hybridization.

背景与目标： ：已研究了烷基三甲基铵离子对天然和修饰的DNA双链体的热稳定性的影响。我们已经表明，使用四甲基铵离子TMA以及双链体的化学修饰可以对T m进行精细调节，并可以获得具有不同等稳定温度的多个双链体系统，其中某些系统显示出比天然DNA更高的稳定性。该方法对于通过杂交进行DNA测序非常有用。

BACKGROUND & AIMS: :Hierarchical Bayesian models are proposed for over-dispersed longitudinal spatially correlated binomial data. This class of models accounts for correlation among regions by using random effects and allows a flexible modelling of spatiotemporal odds by using smoothing splines. The aim is (i) to develop models which will identify temporal trends of odds and produce smoothed maps including regional effects, (ii) to specify Markov chain Monte Carlo (MCMC) inference for fitting such models, (iii) to study the sensitivity of such Bayesian binomial spline spatiotemporal analyses to prior assumptions, and (iv) to compare mechanisms for assessing goodness of fit. An analysis of regional variation for revascularization odds of patients hospitalized for acute coronary syndrome in Quebec motivates and illustrates the methods developed.

背景与目标： ：提出层次贝叶斯模型用于过度分散的纵向空间相关二项式数据。此类模型通过使用随机效应来说明区域之间的相关性，并可以通过使用平滑样条线对时空几率进行灵活的建模。目的是（i）开发能够识别赔率的时间趋势并产生包括区域效应在内的平滑图的模型；（ii）指定马尔可夫链蒙特卡罗（MCMC）推论来拟合此类模型；（iii）研究模型的敏感性。这样的贝叶斯二项式样条时空分析到先前的假设，以及（iv）比较评估拟合优度的机制。对魁北克因急性冠脉综合征住院的患者进行血运重建几率的区域变化进行分析，可以激发并说明所开发的方法。

BACKGROUND & AIMS: :Slow amplitude modulation of human voice was approximated by a sinusoidal wave. The theoretical effects of smoothing window size, F0, and modulation frequency on window amplitude average as well as calculated shimmer were mathematically derived. Subsequently, the theoretical predictions were tested using idealized and real voice signals from normal speakers. The theoretical and experimental results suggest that shimmer (when calculated using a smoothing window) is a function of window duration and modulation frequency. Window duration when defined as a constant number of pitch periods varies from speaker to speaker depending on their F0. It may not be desirable to use local smoothing windows with a constant number of cycles for shimmer computation, especially if voices with known low-frequency amplitude modulations but notably different fundamental frequencies are compared.

背景与目标： ：人声的慢幅度调制由正弦波近似。数学上得出了平滑窗口大小，F0和调制频率对窗口幅度平均值以及计算出的微光的理论影响。随后，使用来自正常扬声器的理想和真实语音信号测试了理论预测。理论和实验结果表明，闪烁（使用平滑窗口计算时）是窗口持续时间和调制频率的函数。当定义为恒定音调周期数时，窗口持续时间因扬声器的F0而异。可能不希望使用具有恒定周期数的局部平滑窗口来进行微光计算，尤其是在比较具有已知低频幅度调制但明显不同的基频的声音的情况下。

BACKGROUND & AIMS: :Stepped leaf edges are the major limitation of conforming to the prescribed treatment contour defined by the conventional multileaf collimator (MLC), which produces a scalloped dose pattern. The commercial HD-270 MLC (HDI) technique provides a software solution of the conventional MLC to achieve smoothed edge and optimal penumbra of the MLC shaped field. We implemented the HDI functionality on a 3D treatment planning system and compared the dosimetric effects of the HDI delivery in simulation with those in experiment for a number of the MLC fields. The fields from the contour of varied shapes with different sizes of the leaf stepping were tested for the HDI delivery. There is a good agreement of the dose distribution between the calculation as implemented in the planning system and the measurement performed on the treatment machine. It has been shown that the HDI delivery significantly smooths the stepped field edge with the reduced isodose undulation and effective penumbra. A problem may be present when the HDI is applied for the treatment of the circular contour of smaller diameter, and the conformity of the MLC shaping may not be achievable satisfactorily with the existing system. The optimization of leaf configuration is suggested to improve the conformity of the HDI technique. The HDI planning then can be used to assist in the decision making of applying the HDI treatment delivery.

背景与目标： ：叶片边缘呈阶梯状是符合常规多叶准直仪（MLC）所定义的规定治疗轮廓的主要限制，它会产生扇贝形的剂量模式。商业HD-270 MLC（HDI）技术提供了常规MLC的软件解决方案，以实现MLC成形场的平滑边缘和最佳半影。我们在3D治疗计划系统上实现了HDI功能，并将HDI交付在模拟中的剂量效应与在许多MLC领域的实验中的剂量效应进行了比较。测试了来自不同形状轮廓和不同叶阶大小的区域的HDI交付情况。在计划系统中执行的计算与在治疗机上执行的测量之间的剂量分布有很好的一致性。业已表明，HDI的输送显着平滑了阶梯状的场边缘，并减少了等剂量的起伏和有效的半影。当将HDI应用于较小直径的圆形轮廓的处理时，可能会出现问题，并且现有系统可能无法令人满意地实现MLC成形的一致性。建议优化叶配置以提高HDI技术的一致性。然后，可以使用HDI规划来协助做出应用HDI处理交付的决策。

BACKGROUND & AIMS: :In the statistical analysis of fMRI data, the parameter of primary interest is the effect of a contrast; of secondary interest is its standard error, and of tertiary interest is the standard error of this standard error, or equivalently, the degrees of freedom (df). In a ReML (Restricted Maximum Likelihood) analysis, we show how spatial smoothing of temporal autocorrelations increases the effective df (but not the smoothness of primary or secondary parameter estimates), so that the amount of smoothing can be chosen in advance to achieve a target df, typically 100. This has already been done at the second level of a hierarchical analysis by smoothing the ratio of random to fixed effects variances (Worsley, K.J., Liao, C., Aston, J.A.D., Petre, V., Duncan, G.H., Morales, F., Evans, A.C., 2002. A general statistical analysis for fMRI data. NeuroImage, 15:1-15); we now show how to do it at the first level, by smoothing autocorrelation parameters. The proposed method is extremely fast and it does not require any image processing. It can be used in conjunction with other regularization methods (Gautama, T., Van Hulle, M.M., in press. Optimal spatial regularisation of autocorrelation estimates in fMRI analysis. NeuroImage.) to avoid unnecessary smoothing beyond 100 df. Our results on a typical 6-min, TR = 3, 1.5-T fMRI data set show that 8.5-mm smoothing is needed to achieve 100 df, and this results in roughly a doubling of detected activations.

背景与目标： ：在功能磁共振成像数据的统计分析中，主要关注的参数是对比度的影响；次要利益是其标准误差，三次利益是该标准误差的标准误差，或者等效地是自由度（df）。在ReML（受限最大似然）分析中，我们显示了时间自相关的空间平滑如何增加有效df（而不是主要或辅助参数估计的平滑度），因此可以提前选择平滑量以实现目标df，通常为100。通过平滑随机效应与固定效应方差的比率（Worsley，KJ，Liao，C.，Aston，JAD，Petre，V.，Duncan，GH ，Morales，F.，Evans，AC，2002. fMRI数据的一般统计分析（NeuroImage，15：1-15）；我们现在展示如何通过平滑自相关参数在第一级上做到这一点。所提出的方法非常快，并且不需要任何图像处理。它可以与其他正则化方法结合使用（印刷中的Gautama，T.，Van Hulle，M.M.。fMRI分析中自相关估计的最佳空间正则化。NeuroImage），以避免超过100 df的不必要平滑。我们在典型的6分钟，TR = 3、1.5-T fMRI数据集上的结果表明，要达到100 df，需要8.5 mm的平滑处理，这导致检测到的激活次数大约增加了一倍。

BACKGROUND & AIMS: :A numerical method to process experimental data concerning plasmid stability of a recombinant bacteria during continuous cultures with nonselective media is proposed here. This method differs from previous ones in that it uses the derivatve form of the state equation of the Imanaka-Aiba model for recombinant cultures. The methodology proposed here allows one to estimate values for the two model parameters without forcing them to be constant. Until now, this could not be done using classical analytical techniques because these parameters have been considered invariable because of the integration used in the evaluation of the model. These parameters are (1) the difference in the specific growth rates between plasmid-carrying cells and plasmid-free cells (deltamu), and (2) the probability of plasmid loss by plasmid-containing cells (rho(r) mu(+)). The derivative technique used here is completed by mathematical treatments involving data filtering and smoothing. The values of the two parameters are in agreement with those already published. The current technique does not impose preconditions and permit us to further study related phenomena.

背景与目标： ：本文提出了一种数值方法，用于处理与非选择性培养基连续培养过程中重组细菌质粒稳定性有关的实验数据。该方法与以前的方法不同之处在于，它使用Imanaka-Aiba模型的状态方程的导数形式进行重组培养。这里提出的方法允许一个人估计两个模型参数的值，而不必强迫它们是恒定的。到现在为止，这不能使用经典的分析技术来完成，因为这些参数由于模型评估中使用的积分而被认为是不变的。这些参数是（1）质粒携带细胞和无质粒细胞之间的比生长速率的差异（deltamu），以及（2）含质粒的细胞（rho（r）mu（）造成质粒丢失的概率。此处使用的导数技术是通过涉及数据过滤和平滑处理的数学处理完成的。这两个参数的值与已经发布的参数一致。当前的技术没有施加先决条件，并允许我们进一步研究相关现象。

BACKGROUND & AIMS: :By use of nonparametric rate smoothing and nucleotide sequences of the rbcL gene, divergence times in Lycopodiaceae are estimated. The results show that much extant species diversity in Lycopodiaceae stems from relatively recent cladogenic events. These results corroborate previous ideas based on paleobotanical and biogeographical data. Previous molecular phylogenetic analyses recognized a split into neotropical and paleotropical clades in Huperzia, which contains 85-90% of all living species. Connecting this biogeographical pattern with continent movements, the diversification of this epiphytic group was suggested to coincide with that of angiosperms in the mid to Late Cretaceous. Results presented here are consistent with this idea, and the diversification of the two clades is resolved as Late Cretacous (78 and 95 Myr). In the related genera Lycopodium and Lycopodiella, the patterns are somewhat different. Here species diversity is scattered among different subgeneric groups. Most of the high-diversity subgeneric groups seem to have diversified very recently (Late Tertiary), whereas the cladogenic events leading to these groups are much older (Early to Late Cretaceous). Our analysis shows that, although much living species diversity stems from relatively recent cladogenesis, the origins of the family (Early Carboniferous) and generic crown groups (Early Permian to Early Jurassic) are much more ancient events.

背景与目标： ：通过使用非参数速率平滑和rbcL基因的核苷酸序列，可以估计番茄科的发散时间。结果表明，番茄科中许多现存的物种多样性源于相对较近的成枝事件。这些结果证实了基于古植物学和生物地理学数据的先前观点。先前的分子系统发育分析认为，石杉属分为新热带和古热带进化枝，其中包含所有活物种的85-90％。将此生物地理模式与大陆运动联系起来，表明该附生类群的多样性与白垩纪中晚期的被子植物相吻合。这里介绍的结果与这个想法是一致的，两个进化枝的多样性被解析为白垩纪晚期（78和95 Myr）。在相关的石蒜属和石蒜属中，模式有所不同。在这里，物种多样性散布在不同的亚属群之间。大多数高度多样性的亚属群似乎最近才多样化（第三纪晚期），而导致这些群体的成岩事件则要早得多（早至白垩纪晚期）。我们的分析表明，尽管许多生物物种的多样性起源于相对较新的近生，但该家族（早期石炭纪）和普通冠群（早二叠纪到侏罗纪早期）的起源却要古老得多。

BACKGROUND & AIMS: :P.J. Green has defined an OSL (one-step late) algorithm that retains the E-step of the EM algorithm (for image reconstruction in emission tomography) but provides an approximate solution to the M-step. Further modifications of the OSL algorithm guarantee convergence to the unique maximum of the log posterior function. Convergence is proved under a specific set of sufficient conditions. Several of these conditions concern the potential function of the Gibb's prior, and a number of candidate potential functions are identified. Generalization of the OSL algorithm to transmission tomography is also considered.

背景与目标： ：P.J。 Green定义了一种OSL（延迟一步）算法，该算法保留了EM算法的E步骤（用于放射线断层摄影中的图像重建），但提供了M步骤的近似解决方案。 OSL算法的进一步修改可确保收敛到对数后验函数的唯一最大值。在特定的一组充分条件下证明了收敛。其中一些条件与吉布先验的潜在功能有关，并且确定了许多候选潜在功能。还考虑将OSL算法推广到透射层析成像。