当前共找到 1063 篇文献分享,本页显示第 601 - 620 篇。
601.
钟鸣 (2022-11-29 00:04):
#paper https://doi.org/10.3389/fvets.2020.00252 ,Frontiers in Veterinary Science,Contagious Yawning in African Elephants (Loxodonta africana): Responses to Other Elephants and Familiar Humans 你可能知道,打哈欠是会传染的,即当看到/听到/想到别人打哈欠时,也会不由自主跟着打哈欠。不仅如此,打哈欠也会在物种间相互传染,目前已知的是人与狗、人与黑猩猩间存在种间传染性打哈欠现象。虽然传染性打哈欠的发生机制和作用还不清楚,但据推测与个体间的社会沟通有关。大象具有高度发达的大脑,且社会化程度很高,为探究大象与人是否存在种间传染性哈欠,本文作者设计了一系列观察实验。实验对象是公园里的7头大象,它们每天按例与饲养员沟通,还要与游客互动。 在正式试验前,作者记录了大象打哈欠的频率:在觉醒时平均18小时打一个哈欠,这表明觉醒时自发打哈欠的频率很低。在正式试验中,饲养员在执行日常训练任务时,直视大象并且做出打哈欠动作(嘴巴缓慢张开、呆住,随后迅速闭合),对照试验为张嘴动作(缓慢张开、缓慢闭合)。结论是观察到了人象之间的种间传染性哈欠。
Abstract:
While spontaneous yawning is common across all vertebrate classes, contagious yawning is less common and has been observed only in a few species of social animals. Interspecific contagious yawning in … >>>
While spontaneous yawning is common across all vertebrate classes, contagious yawning is less common and has been observed only in a few species of social animals. Interspecific contagious yawning in response to yawning by humans has been observed only by chimpanzees and dogs. After confirming additional occurrences of intraspecific contagious yawning in a group of captive African elephants previously studied, we further investigated the potential for the same group of elephants to engage in interspecific contagious yawning with familiar human handlers. Ten captive African elephants, most of whom had been previously studied, were observed over 13 nights for evidence of intraspecific contagious yawning. Seven of these elephants were also involved in trials where familiar handlers performed staged yawns, as well as trials with staged non-yawning gapes, or trials with no yawns or gapes. Incorporating previously collected contagious yawning data, we describe nine instances of intraspecific contagious yawning in the elephants. Three of the seven elephants yawned contagiously in response to humans during the interspecific yawning trials. This is the first report of interspecific contagious yawning by elephants in response to yawns by familiar humans. <<<
翻译
602.
DeDe宝 (2022-11-28 23:47):
#paper https://doi.org/10.1038/s41562-019-0811-3 Nature Human Behaviour volume 4, pages397–411 (2020) Multimodal mapping of the face connectome 面部处理支持人脸识别和情感理解的能力,这依赖于脑区网络分布,但目前研究者对脑区的相互作用知之甚少。本篇文章结合解剖、功能连接测量与行为分析,建立了面部连接体的全脑模型,探明了模型的关键特征,如脑网络拓扑结构和纤维束构成。研究者提出了具有三个核心流的神经认知模型,面部处理流程沿着这些核心流并行或交互处理。虽然长程神经纤维束是很重要,但面部脑网络由短程神经纤维束主导,最后,研究者提供了面部处理流程右偏侧化是由于半球内和半球间连接不平衡的证据。总之,面部脑网络依赖于高度结构化的神经纤维束之间的动态链接,使支持行为和认知的面部处理流程成为可能。
IF:21.400Q1 Nature human behaviour, 2020-04. DOI: 10.1038/s41562-019-0811-3 PMID: 31988441
Abstract:
Face processing supports our ability to recognize friend from foe, form tribes and understand the emotional implications of changes in facial musculature. This skill relies on a distributed network of … >>>
Face processing supports our ability to recognize friend from foe, form tribes and understand the emotional implications of changes in facial musculature. This skill relies on a distributed network of brain regions, but how these regions interact is poorly understood. Here we integrate anatomical and functional connectivity measurements with behavioural assays to create a global model of the face connectome. We dissect key features, such as the network topology and fibre composition. We propose a neurocognitive model with three core streams; face processing along these streams occurs in a parallel and reciprocal manner. Although long-range fibre paths are important, the face network is dominated by short-range fibres. Finally, we provide evidence that the well-known right lateralization of face processing arises from imbalanced intra- and interhemispheric connections. In summary, the face network relies on dynamic communication across highly structured fibre tracts, enabling coherent face processing that underpins behaviour and cognition. <<<
翻译
603.
尹志 (2022-11-28 21:20):
#paper https://doi.org/10.1093/bib/bbab344 Briefings in Bioinformatics, 22(6), 2021, 1-11:Molecular design in drug discovery: a comprehensive review of deep generative models. 一篇基于深度生成模型的药物发现中的分子设计的综述。看年份是比较新的,但其实已经完全不sota了啊,哈哈哈哈哈。但是作为科普是很好的。文章介绍了基于深度生成模型的分子设计这个在药物发现领域的重要主题。综述了两种主流的分子表示:SMILES-based和图based。然后在每个表示下,分别介绍了基于VAE,GAN,RNN,Flow几种深度生成模型的分子设计。同时也介绍了目前市面上主要的de novo的分子设计的数据集。文章的结尾还从数据、模型、评价指标的角度讨论了分子设计目前存在的挑战。不过作者在写这篇综述的时候,可能是万万没想到今年diffusion model会在生成模型领域大杀四方吧,哈哈哈哈
IF:6.800Q1 Briefings in bioinformatics, 2021-11-05. DOI: 10.1093/bib/bbab344 PMID: 34415297
Abstract:
Deep generative models have been an upsurge in the deep learning community since they were proposed. These models are designed for generating new synthetic data including images, videos and texts … >>>
Deep generative models have been an upsurge in the deep learning community since they were proposed. These models are designed for generating new synthetic data including images, videos and texts by fitting the data approximate distributions. In the last few years, deep generative models have shown superior performance in drug discovery especially de novo molecular design. In this study, deep generative models are reviewed to witness the recent advances of de novo molecular design for drug discovery. In addition, we divide those models into two categories based on molecular representations in silico. Then these two classical types of models are reported in detail and discussed about both pros and cons. We also indicate the current challenges in deep generative models for de novo molecular design. De novo molecular design automatically is promising but a long road to be explored. <<<
翻译
604.
惊鸿 (2022-11-28 10:33):
#paper CRISPRing future medicinesExpert Opin. Drug Discov.PubDate:2021-01-03DOI:10.1080/17460441.2021.1850687Laure Grand Moursel 1 , Mijke Visser 1 , Geraldine Servant 1 , Selvi Durmus 1 , Anne-Marie Zuurmond 1这是以快速且具有成本效益的方式设计哺乳动物基因组的能力导致 CRISPR 技术在生物医学研究中的快速适应。基于 CRISPR 的工程具有加速药物发现、支持降低药物开发中的高损耗率以及促进细胞和基因疗法的开发的潜力。CRISPR 技术正迅速成为基因组工程的首选工具,如今很难想象没有这项技术的药物发现管道。随着未来几年,CRISPR 技术无疑将得到进一步完善,并将蓬勃发展成为一项成熟的技术,它将在支持药物发现管道以及细胞和基因治疗开发中的基因组工程要求方面发挥关键作用。
Abstract:
: The ability to engineer mammalian genomes in a quick and cost-effective way has led to rapid adaptation of CRISPR technology in biomedical research. CRISPR-based engineering has the potential to … >>>
: The ability to engineer mammalian genomes in a quick and cost-effective way has led to rapid adaptation of CRISPR technology in biomedical research. CRISPR-based engineering has the potential to accelerate drug discovery, to support the reduction of high attrition rate in drug development and to enhance development of cell and gene-based therapies.: How CRISPR technology is transforming drug discovery is discussed in this review. From target identification to target validation in both and models, CRISPR technology is positively impacting the early stages of drug development by providing a straightforward way to genome engineering. This property also attracted attention for CRISPR application in the cell and gene therapy area.: CRISPR technology is rapidly becoming the preferred tool for genome engineering and nowadays it is hard to imagine the drug discovery pipeline without this technology. With the years to come, CRISPR technology will undoubtedly be further refined and will flourish into a mature technology that will play a key role in supporting genome engineering requirements in the drug discovery pipeline as well as in cell and gene therapy development. <<<
翻译
605.
前进 (2022-11-28 10:25):
#paper Zhu Y , Lu S . Swin-VoxelMorph: A Symmetric Unsupervised Learning Model forDeformable Medical Image Registration Using Swin Transformer[C]// International Conference on Medical Image Computing and Computer-Assisted Intervention. Springer, Cham, 2022. 可变形医学图像配准广泛应用于医学图像处理中,具有可逆一对一的映射。虽然最先进的图像配准方法是基于卷积神经网络,但很少有人尝试用Transformer的方法。现有的模型忽略了在嵌入学习中使用注意机制来处理远程交叉图,限制了这种方法来识别解剖结构的语义上有意义的对应关系。这些方法虽然实现了快速的图像配准,但也忽略了变换的拓扑保存和可逆性。在本文中,提出了一种新的基于Swin Transformer对称无监督学习网络,它可以最小化图像之间的差异,并同时估计正变换和逆变换像相关性.具体地说,本文提出了三维Swin-UNet,它应用具有Shfited window的分层Swin Transformer作为编码器来提取上下文特征。设计了一种基于patch expanding的symmetric swin Transformer解码器,进行上采样操作,估计配准场。此外,目标损失函数可以保证预测变换的实质性微分性质。本文在ADNI和PPMI两个数据集上验证了该方法,并在保持理想的微分性质的同时实现了最先进的配准精度。
Abstract:
Deformable medical image registration is widely used in medical image processing with the invertible and one-to-one mapping between images. While state-of-the-art image registration methods are based on convolutional neural networks, … >>>
Deformable medical image registration is widely used in medical image processing with the invertible and one-to-one mapping between images. While state-of-the-art image registration methods are based on convolutional neural networks, few attempts have been made with Transformers which show impressive performance on computer vision tasks. Existing models neglect to employ attention mechanisms to handle the long-range cross-image relevance in embedding learning, limiting such approaches to identify the semantically meaningful correspondence of anatomical structures. These methods also ignore the topology preservation and invertibility of the transformation although they achieve fast image registration. In this paper, we propose a novel, symmetric unsupervised learning network Swin-VoxelMorph based on the Swin Transformer which minimizes the dissimilarity between images and estimates both forward and inverse transformations simultaneously. Specifically, we propose 3D Swin-UNet, which applies hierarchical Swin Transformer with shifted windows as the encoder to extract context features. And a symmetric Swin Transformer-based decoder with patch expanding layer is designed to perform the up-sampling operation to estimate the registration fields. Besides, our objective loss functions can guarantee substantial diffeomorphic properties of the predicted transformations. We verify our method on two datasets including ADNI and PPMI, and it achieves state-of-the-art registration accuracy while maintaining desirable diffeomorphic properties. <<<
翻译
606.
林李泽强 (2022-11-27 19:25):
#paper https://doi.org/10.1002/hbm.25980 Human Brain Mapping, 2022: Voxel-wise intermodal coupling analysis of two or more modalities using local covariance decomposition. 这篇文章提出了一种新的多模态耦合的方法——基于协方差特征分解的耦合方法,这种方法解决了先前相关的研究中耦合值不对称以及仅限两种模态的缺点(Vandekar et al., 2016)。 该方法使用局部协方差分解(主成分分析中的最大特征值的方差占比)来定义对两个或多个模态有效的对称体素耦合值,较大的值表明体素的跨模态的局部协方差矩阵可以在单个维度中很好地概括。此外,作者还验证中这个指标的生物相关性,即验证该指标与年龄或性别的相关性。
IF:3.500Q1 Human brain mapping, 2022-10-15. DOI: 10.1002/hbm.25980 PMID: 35730989
Abstract:
When individual subjects are imaged with multiple modalities, biological information is present not only within each modality, but also between modalities - that is, in how modalities covary at the … >>>
When individual subjects are imaged with multiple modalities, biological information is present not only within each modality, but also between modalities - that is, in how modalities covary at the voxel level. Previous studies have shown that local covariance structures between modalities, or intermodal coupling (IMCo), can be summarized for two modalities, and that two-modality IMCo reveals otherwise undiscovered patterns in neurodevelopment and certain diseases. However, previous IMCo methods are based on the slopes of local weighted linear regression lines, which are inherently asymmetric and limited to the two-modality setting. Here, we present a generalization of IMCo estimation which uses local covariance decompositions to define a symmetric, voxel-wise coupling coefficient that is valid for two or more modalities. We use this method to study coupling between cerebral blood flow, amplitude of low frequency fluctuations, and local connectivity in 803 subjects ages 8 through 22. We demonstrate that coupling is spatially heterogeneous, varies with respect to age and sex in neurodevelopment, and reveals patterns that are not present in individual modalities. As availability of multi-modal data continues to increase, principal-component-based IMCo (pIMCo) offers a powerful approach for summarizing relationships between multiple aspects of brain structure and function. An R package for estimating pIMCo is available at: https://github.com/hufengling/pIMCo. <<<
翻译
607.
李翛然 (2022-11-26 21:39):
#paper https://www.who.int/publications/m/item/plasmid-dna-vaccines-annex-2-trs-no-1028 Guidelines on the quality, safety and efficacy of plasmid DNA vaccines 最近由于工作原因,在跟踪一家国内第一个获得IND药物审批的DNA疫苗,主要团队都工作的接触,还是非常佩服的。全程听了他们的研发流程和路演,确实也经历了非常多的困难。 不过这项技术真的是走在了世界前列。 不过,我这个外行对于直接操作dna 还是或多或少有一些谨慎。 所以找来了这个WHO的指导原则仔细看了看, 结论感觉跟当年的mrna一样,都是暂未发现,但是大规模临床后如何呢? 只能是时间给答案了。
Abstract:
Since the 1990s, a novel third approach to vaccination against a broad array of target antigens and diseases has been in development. This technology involves the direct administration of plasmid … >>>
Since the 1990s, a novel third approach to vaccination against a broad array of target antigens and diseases has been in development. This technology involves the direct administration of plasmid deoxyribonucleic acid (DNA) containing the gene encoding the immunogen against which an immune response is sought, leading to the in-situ production of the target immunogen(s) in the vaccine recipient. Such vaccines are referred to as “plasmid DNA vaccines” or simply “DNA vaccines” (with both terms used interchangeably throughout these Guidelines). The value and advantages of plasmid DNA products need to be assessed on a case-by-case basis; their utility will depend upon: (a) the nature of the organism being vaccinated against or the targeted disease; (b) the nature of the immunogen or activity of the gene insert; (c) the type of immune response required for effectiveness; and (d) the delivery system and route of administration. The development and application of DNA vaccines continues to progress. Since the WHO Guidelines for assuring the quality and nonclinical safety evaluation of DNA vaccines were adopted by the Expert Committee for Biological Standardization in 2005, many clinical trials of DNA vaccines have taken place and considerable experience in their manufacture and control has accrued. The current revision reflects this experience, especially in relation to data derived from nonclinical and clinical safety testing, which address many of the concerns expressed in previous versions of these Guidelines. The control of DNA vaccines should continue to be approached in a flexible manner to enable further modifications as more experience is gained in their production and use, and as other components or delivery systems are included. The intention of the current document is to provide a scientifically sound basis for the consistent manufacture and control of DNA vaccines for human use to ensure their continued safety and efficacy following licensure. <<<
翻译
608.
徐炳祥 (2022-11-23 13:30):
#paper doi:10.1038/s41592-021-01248-7 Nature methods, 2021, Systematic evaluation of chromosome conformation capture assays。染色质空间构象捕获(3C)及由其衍生的一系列技术是当前研究真核生物染色质空间组织模式的主要高通量手段,已经取得了多项重要发现。目前,多个实验室已发展了多套不同的实验流程。本文对这些流程中的主要差异点,包括交联剂配方,使用的内切酶等对实验结果的影响进行了详细分析。通过对比多个细胞类型的结果,作者找到了最优的交联剂配方和内切酶类型,发展了一套新的,能同时适用于染色质结构与和染色质环检测的新Hi-C实验流程。
IF:36.100Q1 Nature methods, 2021-09. DOI: 10.1038/s41592-021-01248-7 PMID: 34480151
Abstract:
Chromosome conformation capture (3C) assays are used to map chromatin interactions genome-wide. Chromatin interaction maps provide insights into the spatial organization of chromosomes and the mechanisms by which they fold. … >>>
Chromosome conformation capture (3C) assays are used to map chromatin interactions genome-wide. Chromatin interaction maps provide insights into the spatial organization of chromosomes and the mechanisms by which they fold. Hi-C and Micro-C are widely used 3C protocols that differ in key experimental parameters including cross-linking chemistry and chromatin fragmentation strategy. To understand how the choice of experimental protocol determines the ability to detect and quantify aspects of chromosome folding we have performed a systematic evaluation of 3C experimental parameters. We identified optimal protocol variants for either loop or compartment detection, optimizing fragment size and cross-linking chemistry. We used this knowledge to develop a greatly improved Hi-C protocol (Hi-C 3.0) that can detect both loops and compartments relatively effectively. In addition to providing benchmarked protocols, this work produced ultra-deep chromatin interaction maps using Micro-C, conventional Hi-C and Hi-C 3.0 for key cell lines used by the 4D Nucleome project. <<<
翻译
609.
负负 (2022-11-22 13:51):
#paper https://doi.org/10.1016/j.neuroimage.2021.118423. NeuroImage, 2021, Representation learning of resting state fMRI with variational autoencoder. 这篇文章是变分自编码器(VAE)在静息态磁共振成像上进行表征学习的一次尝试。该团队使用了HCP的650个健康被试的静息态磁共振影像,利用FreeSurfer工具将单个被试的BOLD信号volume数据(仅皮层)映射至球面,之后再利用极坐标转换(用横向和纵向偏转角度描述)至二维平面,将该“二维平面激活图”输入VAE训练。主要研究结论: 1、VAE对rfMRI的重建效果显著优于PCA、GIFT等数据重建方法,但会对全脑BOLD信号造成smooth效果。在VAE的latent space上随机重采样重建数据,进一步计算出的seed-based FC或FCS都具有很高的可重复性。 2、训练集不包括fMRI的时间维度的信息,但是研究发现volume的全脑BOLD信号映射至latent space后随着时间序列推移存在某些特定的运动规律(例如主要沿着某些方向运动),这是由某些脑区(感觉运动、初级视觉、听觉等)的独特激活模式造成的。 3、t-SNE分析发现来自同一被试的volume数据聚为一类,说明VAE学习到了每个被试独特的BOLD信号激活模式,这是其他数据重建算法(PCA等)无法做到的。 4、无论是在latent space还是在reconstruction space,VAE都保留了被试间和被试内(不同session之间)的相似性。
IF:4.700Q1 NeuroImage, 2021-11-01. DOI: 10.1016/j.neuroimage.2021.118423 PMID: 34303794
Abstract:
Resting state functional magnetic resonance imaging (rsfMRI) data exhibits complex but structured patterns. However, the underlying origins are unclear and entangled in rsfMRI data. Here we establish a variational auto-encoder, … >>>
Resting state functional magnetic resonance imaging (rsfMRI) data exhibits complex but structured patterns. However, the underlying origins are unclear and entangled in rsfMRI data. Here we establish a variational auto-encoder, as a generative model trainable with unsupervised learning, to disentangle the unknown sources of rsfMRI activity. After being trained with large data from the Human Connectome Project, the model has learned to represent and generate patterns of cortical activity and connectivity using latent variables. The latent representation and its trajectory represent the spatiotemporal characteristics of rsfMRI activity. The latent variables reflect the principal gradients of the latent trajectory and drive activity changes in cortical networks. Representational geometry captured as covariance or correlation between latent variables, rather than cortical connectivity, can be used as a more reliable feature to accurately identify subjects from a large group, even if only a short period of data is available in each subject. Our results demonstrate that VAE is a valuable addition to existing tools, particularly suited for unsupervised representation learning of resting state fMRI activity. <<<
翻译
610.
颜林林 (2022-11-20 22:18):
#paper doi:10.1093/bioinformatics/btac018 Bioinformatics, 2022, StainedGlass: interactive visualization of massive tandem repeat structures with identity heatmaps. 这篇paper介绍了来自华盛顿大学Evan Eichler团队的一个小工具,它在基因组尺度上计算序列之间的一致性(或相似性),并以基因组浏览器上通常展示连锁不平衡(LD)的三角形方式,展示这些序列一致性关系。这几乎就只是一项日常分析工作中的普通任务,谈不上多大的创新性和重要意义。因此,作为一篇可以帮助其他人复用并快速实现类似功能的Application Note,作者将该功能封装成为snakemake模块,并且借用另一个发表于2018年的工具HiGlass,实现结果的交互式展示,允许快速进行不同分辨率的调节,倒是确实突出了实用性。
Abstract:
SUMMARY: The visualization and analysis of genomic repeats is typically accomplished using dot plots; however, the emergence of telomere-to-telomere assemblies with multi-megabase repeats requires new visualization strategies. Here, we introduce … >>>
SUMMARY: The visualization and analysis of genomic repeats is typically accomplished using dot plots; however, the emergence of telomere-to-telomere assemblies with multi-megabase repeats requires new visualization strategies. Here, we introduce StainedGlass, which can generate publication-quality figures and interactive visualizations that depict the identity and orientation of multi-megabase tandem repeat structures at a genome-wide scale. The tool can rapidly reveal higher-order structures and improve the inference of evolutionary history for some of the most complex regions of genomes.AVAILABILITY AND IMPLEMENTATION: StainedGlass is implemented using Snakemake and available open source under the MIT license at https://mrvollger.github.io/StainedGlass/.SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online. <<<
翻译
611.
张德祥 (2022-11-19 07:13):
#paper https://doi.org/10.1038/nrn2787 The free-energy principle: a unified brain theory? 自由能原理,说明了行动、感知和学习。这篇评论从自由能的角度审视了生物(如神经达尔文主义)和物理(如信息理论和最优控制理论)科学中的一些关键大脑理论。至关重要的是,有一个关键的主题贯穿了这些理论中的每一个--优化。此外,如果我们仔细观察被优化的东西,同样的数量不断出现,即价值(预期奖励,预期效用)或其补充,惊喜(预测错误,预期成本)。这就是在自由能量原理下被优化的数量,这表明几个全局性的大脑理论可能在自由能量框架内被统一起来。 生物系统的生理学几乎可以完全还原为它们的稳态。更确切地说,生物体所处的生理和感觉状态是有限的,这些状态决定了生物体的表型。数学上,这意味着这些(内感受和外感受)感觉状态的概率必须具有低熵;换句话说,系统很有可能处于少数状态中的任何一种,而处于其余状态的可能性很小。熵也是平均自我信息或“惊喜”8(更正式地说,它是一个结果的负对数概率)。在这里,“一条离开水的鱼”将处于一种震惊的状态(无论是情感上还是数学上)。一条经常离开水的鱼会有高熵值。 贝叶斯大脑假说 使用贝叶斯概率理论将感知表述为基于内部或生成模型的建构过程。潜在的想法是,大脑有一个世界模型 ,它试图使用感觉输入来优化它。这个想法与综合分析 和认识论自动化 有关。根据这种观点,大脑是一个 推 理 机 器 , 它 积 极 地 预 测 和 解 释 它 的 感 觉。这个假设的核心是一个可以产生预测的概率模型,根据这个模型,感官样本被测试来更新对其原因的信念。这个生成模型被分解成一个可能性(给定原因的感觉数据的概率)和一个先验(这些原因的先验概率)。然后,感知成为反转可能性模型(从原因到感觉的映射)的过程,以访问给定感觉数据(从感觉到原因的映射)的原因的后验概率。 这种反演与最小化识别密度和后验密度之间的差异以抑制自由能是一样的。事实上,开发自由能模拟是为了通过将其转化为更简单的优化问题来解决精确推理的难题 。这为模型识别和比较提供了一些强大的近似技术(例如,变分贝叶斯或集成学习)。贝叶斯大脑假说伴随着许多有趣的问题, 这些问题可以用自由能原理来解
Abstract:
A free-energy principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and … >>>
A free-energy principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and physical (for example, information theory and optimal control theory) sciences from the free-energy perspective. Crucially, one key theme runs through each of these theories - optimization. Furthermore, if we look closely at what is optimized, the same quantity keeps emerging, namely value (expected reward, expected utility) or its complement, surprise (prediction error, expected cost). This is the quantity that is optimized under the free-energy principle, which suggests that several global brain theories might be unified within a free-energy framework. <<<
翻译
612.
庞庞 (2022-11-17 18:14):
​#paper https://doi.org/10.1073/pnas.2110416119 Sex differences in the functional topography of association networks in youth 之前的工作已经证实,大脑皮层功能网络的空间分布存在个体间差异。然而,至今仍不知道年轻人大脑功能网络形态是否存在性别差异。该研究基于693个年轻人被试,使用NMF定义个体的功能网络,并使用多变量(LSVM)模型,用个体功能形态指标对性别进行分类,准确率达到82.9%,对预测做出显著贡献的脑区分布在联合网络:包括额顶网络,默认模式网络,背外侧注意网络。同时,作者也使用单变量(GAM)模型探究形态指标和性别的关系,发现了一致的结果。最后,作者使用艾伦脑图谱的基因表达数据,揭示了功能形态存在差异的脑区与X染色体的基因表达相关。综上,该研究表明性别是塑性功能形态的重要生物因素。
Abstract:
Prior work has shown that there is substantial interindividual variation in the spatial distribution of functional networks across the cerebral cortex, or functional topography. However, it remains unknown whether there … >>>
Prior work has shown that there is substantial interindividual variation in the spatial distribution of functional networks across the cerebral cortex, or functional topography. However, it remains unknown whether there are sex differences in the topography of individualized networks in youth. Here, we leveraged an advanced machine learning method (sparsity-regularized non-negative matrix factorization) to define individualized functional networks in 693 youth (ages 8 to 23 y) who underwent functional MRI as part of the Philadelphia Neurodevelopmental Cohort. Multivariate pattern analysis using support vector machines classified participant sex based on functional topography with 82.9% accuracy ( < 0.0001). Brain regions most effective in classifying participant sex belonged to association networks, including the ventral attention, default mode, and frontoparietal networks. Mass univariate analyses using generalized additive models with penalized splines provided convergent results. Furthermore, transcriptomic data from the Allen Human Brain Atlas revealed that sex differences in multivariate patterns of functional topography were spatially correlated with the expression of genes on the X chromosome. These results highlight the role of sex as a biological variable in shaping functional topography. <<<
翻译
613.
张德祥 (2022-11-16 09:16):
#paper https://doi.org/10.48550/arXiv.2206.02063 Active Bayesian Causal Inference :We sequentially design experiments that are maximally informative about our target causal query, collect the corresponding interventional data, and update our beliefs to choose the next experiment; 目前的工作中,我们考虑了更一般的设置,其中我们有兴趣进行因果推理,但没有获得参考因果模型的先验。 在这种情况下,因果发现可以被视为达到目的的手段,而不是主要目标。由于两个原因, 专注于主动学习完整的因果模型以实现随后的因果推理可能是不利的。首先,如果我们只对因果模型的特定方面感兴趣,那么浪费样本来学习完整的因果图是次优的。其次,从少量数据中发现因果关系会带来显著的认知不确定性; 我们提出了主动贝叶斯因果推理(ABCI),这是一个完全贝叶斯框架,用于整合因果发现和推理与实验设计。基本方法是将贝叶斯先验置于选择的因果模型类之上, 并将学习问题作为贝叶斯推理置于模型后验之上。给定未观察的因果模型,我们通过引入目标因果查询来形式化因果推理 ; 我们遵循贝叶斯最优实验设计方法[10,42]然后根据我们当前的信念,在真正的因果模型上选择最能提供我们目标查询信息的可接受的干预。给定观察到的数据,我们然后通过计算因果模型和查询的后验来更新我们的信念,并使用它们来设计下一个实验。
Abstract:
Causal discovery and causal reasoning are classically treated as separate and consecutive tasks: one first infers the causal graph, and then uses it to estimate causal effects of interventions. However, … >>>
Causal discovery and causal reasoning are classically treated as separate and consecutive tasks: one first infers the causal graph, and then uses it to estimate causal effects of interventions. However, such a two-stage approach is uneconomical, especially in terms of actively collected interventional data, since the causal query of interest may not require a fully-specified causal model. From a Bayesian perspective, it is also unnatural, since a causal query (e.g., the causal graph or some causal effect) can be viewed as a latent quantity subject to posterior inference -- other unobserved quantities that are not of direct interest (e.g., the full causal model) ought to be marginalized out in this process and contribute to our epistemic uncertainty. In this work, we propose Active Bayesian Causal Inference (ABCI), a fully-Bayesian active learning framework for integrated causal discovery and reasoning, which jointly infers a posterior over causal models and queries of interest. In our approach to ABCI, we focus on the class of causally-sufficient, nonlinear additive noise models, which we model using Gaussian processes. We sequentially design experiments that are maximally informative about our target causal query, collect the corresponding interventional data, and update our beliefs to choose the next experiment. Through simulations, we demonstrate that our approach is more data-efficient than several baselines that only focus on learning the full causal graph. This allows us to accurately learn downstream causal queries from fewer samples while providing well-calibrated uncertainty estimates for the quantities of interest. <<<
翻译
614.
张德祥 (2022-11-16 08:17):
​#paper https://doi.org/10.48550/arXiv.2204.14170 Tractable Uncertainty for Structure Learning 不幸的是,DAGs 的超指数空间使得表示和学习这样的后验概率都极具挑战性。一个重大突破是引入了基于order的表示(Friedman & Koller,2003),其中状态空间被简化为拓扑序的空间,即使这样,任然难于计算。 基于样本的表征对后验的覆盖非常有限,限制了它们所能提供的信息。例如,考虑在给定任意一组所需边的情况下,寻找最可能的图扩展的问题。给定超指数空间,即使是大样本也可能不包含与给定边集一致的单个订单,这使得回答这样的查询是不可能的。 因此需要寻找紧凑的表示。 利用阶模分布中存在的精确的层次条件独立性。这允许OrderSPNs 在相对于其大小的潜在指数级更大的订单集合上表达分布。提供线性时间的Bayesian causal effects因果计算。
Abstract:
Bayesian structure learning allows one to capture uncertainty over the causal directed acyclic graph (DAG) responsible for generating given data. In this work, we present Tractable Uncertainty for STructure learning … >>>
Bayesian structure learning allows one to capture uncertainty over the causal directed acyclic graph (DAG) responsible for generating given data. In this work, we present Tractable Uncertainty for STructure learning (TRUST), a framework for approximate posterior inference that relies on probabilistic circuits as the representation of our posterior belief. In contrast to sample-based posterior approximations, our representation can capture a much richer space of DAGs, while also being able to tractably reason about the uncertainty through a range of useful inference queries. We empirically show how probabilistic circuits can be used as an augmented representation for structure learning methods, leading to improvement in both the quality of inferred structures and posterior uncertainty. Experimental results on conditional query answering further demonstrate the practical utility of the representational capacity of TRUST. <<<
翻译
615.
张德祥 (2022-11-14 14:39):
#paper https://doi.org/10.48550/arXiv.2210.12761 Path integrals, particular kinds, and strange things FEP 是一个第一原理解释或方法,可以应用于任何“事物”, 以某种方式消除物理学、生物学和心理学之间的界限。 这种应用认可了许多关于感知行为和自组织的规范性解释。 范围从控制论到协同学(敖,2004;阿什比,1979 年;哈肯,1983;凯尔索,2021); 从强化学习到人工好奇心(巴尔托等人,2013;施密德胡伯,1991;萨顿和巴尔托,1981 年;Tsividis 等人,2021 年); 从预测处理到通用计算(Clark,2013bHohwy,2016;赫特,2006); 从模型预测控制到empowerment(Hafner 等人,2020;Klyubin 等人,2005),等等。 文章用统计物理学和信息论的标准结果来解开上面叙述的论点。
Abstract:
This paper describes a path integral formulation of the free energy principle. The ensuing account expresses the paths or trajectories that a particle takes as it evolves over time. The … >>>
This paper describes a path integral formulation of the free energy principle. The ensuing account expresses the paths or trajectories that a particle takes as it evolves over time. The main results are a method or principle of least action that can be used to emulate the behaviour of particles in open exchange with their external milieu. Particles are defined by a particular partition, in which internal states are individuated from external states by active and sensory blanket states. The variational principle at hand allows one to interpret internal dynamics - of certain kinds of particles - as inferring external states that are hidden behind blanket states. We consider different kinds of particles, and to what extent they can be imbued with an elementary form of inference or sentience. Specifically, we consider the distinction between dissipative and conservative particles, inert and active particles and, finally, ordinary and strange particles. Strange particles (look as if they) infer their own actions, endowing them with apparent autonomy or agency. In short - of the kinds of particles afforded by a particular partition - strange kinds may be apt for describing sentient behaviour. <<<
翻译
616.
半面阳光 (2022-11-12 18:32):
#paper DOI: 10.1126/science.35.896.340 Science, 1912, First use of word “genotype”. 这篇文章1921年3月1日发表在Science杂志,是一篇Letter,作者Henry Fairfield Osborn。文章非常短,只有几百字。主要内容是讨论“genotype”这个词的使用起源。作者向当时的一位权威命名学和分类学家Dr Joel Asaph Allen询问“genotype”这个词首次被使用的情形。Dr Joel Asaph Allen回复说他认为genotype这个词最早使用是在1903年,并且在1910年之前获得了国际动物学委员会(International Zoological Commission)官方认可,最早应该是被Nature或Annals and magazine of Natural History杂志的作者所用。Genotype词源于希腊语的两个词,语义是“kind, genus” 和“type”。这个合成词中间用“O”这个元音进行连接。但是作者提出为什么没有像genetic和genesis一样用元音“E”来连接呢?作者提出理清“genotype”一词的使用问题,可以避免后续使用中可能出现的混淆情况。这篇Letter类似“社交媒体”类的分享,感觉很像1900年代的朋友圈。因为本文的信息量太少,原文中有些内容读起来有点一头雾水。根据文章提到的一些人和概念,去回溯了几篇文章,发现当时对“Genotype”这个词的使用似乎很有争议,类似于引发了一波当时的“骂战”。1921年3月29日的Science杂志的Letter版块,又有一篇名为The use of the word “genotype”的文章,讨论学术界对这个词使用中的不同意见。另外,这个词还引出了一个对遗传学发展有重要影响的人Wilhelm Ludvig Johannsen,他被认为是Gene、Genotype、Phenotype这些概念的创造者,以及遗传学科的奠基人之一。在双螺旋结构发现之前,遗传学领域的发展和历史应该很热闹,只是课本以及平时工作研究所看的文献中,很少有机会读到这种更偏向于生物学历史研究的文章。另外,这个作者Henry Fairfield Osborn除了是一个著名的古生物学者,担任美国自然历史博物馆馆长达25年,还是个富二代,他的父亲是当时著名的铁路大亨William Henry Osborn。
IF:44.700Q1 Science, 2006. DOI: 10.1126/science.35.896.340
Abstract: No abstract available.
617.
张浩彬 (2022-11-10 00:03):
#paper Momentum Contrast for Unsupervised Visual Representation Learning doi:10.1109/cvpr42600.2020.00975 大名鼎鼎的moco。之前只是粗略了解,今天算是认真精读了一下。受nlp的影响,cv也开始了自监督方法的新一代卷了。 自监督,其实也是无监督了。倒是为了和前人分开,又起了self supervised learning的名字。moco这篇论文,算是趟平了有监督和无监督的差距了,第一次用无监督的方法取得了比有监督预训练任务更好的结果。毕竟人工打标签还是很贵的,如果可以利用无监督的方法对模型进行预训练,那么可以说大大降低了受限于标注数据的性能瓶颈了。 说回本文的技术,可以算是自监督目前的一个主流了(另一个是生成式)。在对比学习中,关键在于:1代理任务;2损失函数。当然本文的突出主要贡献还是在于动量更新方法。 1.moco中的代理任务,选择了比较简单的个体判别,即对于原始数据某个样本x_i,通过两个不同的数据增强,获得锚点样本和正样本;而其他样本,则是相对于该基础样本的负样本。另外,作者提到,把锚点称之为q(query),正样本和负样本对称之为k(key)。 2.损失函数是infonce,本质是其实还是类似于softmax。但是考虑到我们有这么多负样本,实际上就有这么多类别,所以选用了infonce,超参数是“温度” 3.接下里是本文的两个贡献,或者说回归对比学习,作者也提到受到两个问题制约:1是字典大小;2是字典一致性(字典姑且理解为负样本集,对比学习中,负样本集越大越好。另外moco是一个正样本,但也有文献证明,使用多个正样本更好)。(1)字典大小问题:在simclr这样的方法中,实际上每个batch都是对应的字典,这样就保证字典一致性,但是问题是字典大小受限制。要对这么多一个字典是反向传播,需要GPU非常大的内存,其次就是大batchsize的优化,相对也更难。(2)字典一致性问题:相比于simclr这样的端到端方法,另一个套路是使用memory bank的方式。我们依然有一个很大的字典,每次从字典抽样k个负样本进行梯度更新。但是这样的问题在于每次我们只更新了抽样的k个样本,实际上,这时候整个字典的特征是很不一致的(因为我们每次用一个较大梯度去更新所选k个样本,这样对于一个大字典,一个epoch后,第一次更新和最后一次更新的特征会差别很大) 4.针对以上问题,作者首先提出队列作为字典。即每次更新新的特征后,最久的特征剔除出字典,新的特征进度。 5.其次就是动量更新。及我们依然使用梯度下降更新q的encoder。但是我们不再使用梯度更新更细k的encoder,而是使用动量的方式,即,(另外,初始化时,k的encoder是直接复制q的encoder)并且m选择一个非常大的数,例如0.999,这就保证了每次更新都只更新一点,从而保证了字典一致性。 5.接下里是下游任务实现。作者冻结了主干网络,之后只使用了Linear Classification Protocol(一个全连接层和softmax层)作为最后的分类器,与经过ImageNet预训练后的其他模型进行比较,除少部分任务外,moco基本都取得了sota结果。 6.另一个有意思的地方是,moco的分类器,用girdsearch日常搜索发现最优的学习率是30.作者解释到,这也说明了自监督得到的特征确实与有监督得到的特征差别很大。另外在后续比较中,考虑到使用grid search不方便,作者使用了归一化处理。
Abstract:
We present Momentum Contrast (MoCo) for unsupervised visual representation learning. From a perspective on contrastive learning as dictionary look-up, we build a dynamic dictionary with a queue and a moving-averaged … >>>
We present Momentum Contrast (MoCo) for unsupervised visual representation learning. From a perspective on contrastive learning as dictionary look-up, we build a dynamic dictionary with a queue and a moving-averaged encoder. This enables building a large and consistent dictionary on-the-fly that facilitates contrastive unsupervised learning. MoCo provides competitive results under the common linear protocol on ImageNet classification. More importantly, the representations learned by MoCo transfer well to downstream tasks. MoCo can outperform its supervised pre-training counterpart in 7 detection/segmentation tasks on PASCAL VOC, COCO, and other datasets, sometimes surpassing it by large margins. This suggests that the gap between unsupervised and supervised representation learning has been largely closed in many vision tasks. <<<
翻译
618.
龙海晨 (2022-11-01 23:04):
#paper Vicente M, Schlebusch C M. African population history: an ancient DNA perspective[J]. Current Opinion in Genetics & Development, 2020, 62: 8-15. PMID: 32563853  DOI: 10.1016/j.gde.2020.05.008 上次我分享了基因和考古相关的一篇实验论著,结果几天后公布的诺贝尔奖和这项技术相关。发现群里不少人对这个方向感兴趣。这次给大家推荐一篇综述。这篇综述所涉及的领域就是通过一个古老的DNA视角去看非洲的人口历史。如果对于基因考古感兴趣的朋友,除了这篇综述之外,该综述的参考文献也推荐阅读。这篇文章通过总结相关的研究文献。通过研究非洲大陆现代人类,古代人类,远古人类的遗传基因,与考古发现相关联对比,研究非洲大陆从狩猎采集到农耕文明以及现代的文明发展。从现代和史前非洲人的不同群体中获得完整的基因组数据。随着这项技术的发展,未来的古代DNA研究有望 揭示更详细的非洲人类史前故事。人类的历史研究以前通过考古文字,基因技术的加入,可以把研究人类的历史推进到没有文字没有金属的远古时代。基因技术不仅研究未来,也研究过去。文章介绍了考古所用的ancient DNA 的技术发展。在非洲大陆上考古,各个地区,国家,部落,文明的研究与基因技术考古的运用。对基因考古人类文明感兴趣的朋友,推荐阅读该文章和文章的参考文献。
Abstract:
The history of human populations in Africa is complex and includes various demographic events that influenced patterns of genetic variation across the continent. Through genetic studies of modern-day, and most … >>>
The history of human populations in Africa is complex and includes various demographic events that influenced patterns of genetic variation across the continent. Through genetic studies of modern-day, and most recently, ancient African genetic variation, it became evident that deep African history is captured by the relationships among hunter-gatherers. Furthermore, it was shown that agriculture had a large influence on the distribution of current-day Africans. These later population movements changed the demographic face of the continent and descendants of farming groups today form the majority populations across Africa. Ancient DNA methods are continually evolving, and we see evidence of this in how research has advanced in the last decade. With the increased availability of full genomic data from diverse sets of modern-day and prehistoric Africans we now have more power to infer human demography. Future ancient DNA research promises to reveal more detailed stories of human prehistory in Africa. <<<
翻译
619.
小擎子 (2022-10-31 23:59):
#paper doi:10.1126/science.aao3290 Science, 2019, The commensal microbiome is associated with anti-PD-1 efficacy in metastatic melanoma patients. 共生微生物组与转移性黑色素瘤患者的抗PD-1疗效相关,对免疫治疗有反应为R组,无反应为NR组。 文章开始用了16S测序、宏基因组测序和定量PCR,后比较发现,宏基因组的数据在R与NR的差异代表物种较少且与16S重叠(比较奇怪),后选用16S测序来做分析。在R组中,细菌物种, Bifidobacterium longum(长双歧杆菌), Collinsella aerofaciens(科林塞拉菌)和 Enterococcus faecium(屎肠球菌)含量较高,通过无菌小鼠实验,确认来自R组的粪便可以改善肿瘤控制,增强T细胞反应,提供抗PD-L1治疗的疗效。文献结尾的话,“除了微生物组之外,其他肿瘤和宿主因素会影响抗肿瘤免疫和癌症免疫治疗的疗效。Wnt/β-连环蛋白通路的肿瘤内在激活和Pte的缺失或突变已被证明会导致 T细胞浸润不足进入肿瘤微环境和对检查点阻断免疫疗法的耐药性。免疫调节基因中的种系多态性也有可能影响自发抗肿瘤T细胞反应的程度。我们在这里描述的结果开辟了将共生微生物组成以及肿瘤基因组学和种系遗传学整合到多参数模型中的途径,该模型可以最大限度地提高预测哪些患者可能对抗PD-1等免疫疗法产生反应的能力。”
Abstract:
Anti-PD-1-based immunotherapy has had a major impact on cancer treatment but has only benefited a subset of patients. Among the variables that could contribute to interpatient heterogeneity is differential composition … >>>
Anti-PD-1-based immunotherapy has had a major impact on cancer treatment but has only benefited a subset of patients. Among the variables that could contribute to interpatient heterogeneity is differential composition of the patients' microbiome, which has been shown to affect antitumor immunity and immunotherapy efficacy in preclinical mouse models. We analyzed baseline stool samples from metastatic melanoma patients before immunotherapy treatment, through an integration of 16 ribosomal RNA gene sequencing, metagenomic shotgun sequencing, and quantitative polymerase chain reaction for selected bacteria. A significant association was observed between commensal microbial composition and clinical response. Bacterial species more abundant in responders included , , and Reconstitution of germ-free mice with fecal material from responding patients could lead to improved tumor control, augmented T cell responses, and greater efficacy of anti-PD-L1 therapy. Our results suggest that the commensal microbiome may have a mechanistic impact on antitumor immunity in human cancer patients. <<<
翻译
620.
沈么是快乐星球 (2022-10-31 23:36):
#paper doi/abs/10.1111/nph.16552 1)Genome sequencing and assembly of L. japonica. 金银花基因组测序和组装。 2)Genome annotation and whole-genome duplication. 基因组注释与全基因组复制。系统发育分析,发现金银花与菊花、莴苣的亲缘关系最为密切,与菊花分化时间为87Ma。 3)Carotenoid accumulation at different stages of flower development. 花发育不同阶段类胡萝卜素的积累。类胡萝卜素浓度随着花的成熟而先降低后急剧增加,UPLC检测发现:叶黄素和β-胡萝卜素是不同花发育阶段的两种主要化合物。 4)Evolution and expression analysis of carotenogenesis genes. 胡萝卜素基因的进化和表达分析。PSY基因在金银花中扩张成一个小的基因家族,LjPSY1和LjPSY3同源基因可能是金银花WGD事件的产物。 5)Evolution and functional identification of carotenoid cleavage dioxygenases in flower coloration. 花着色中类胡萝卜素裂解双加氧酶(CCD)的进化和功能鉴定。全基因组的分析鉴定出7个CCD基因,5个亚家族,其中LjCCD4 和 LjCCD1b表达量比较高。体外酶活测定发现LjCCD4 和 LjCCD1b表达蛋白可将β-胡萝卜素、叶黄素和100-apo-β-胡萝卜素转化为无色和挥发性物质导致颜色发生变化。
Abstract:
Lonicera japonica is a widespread member of the Caprifoliaceae (honeysuckle) family utilized in traditional medical practices. This twining vine honeysuckle also is a much-sought ornamental, in part due to its … >>>
Lonicera japonica is a widespread member of the Caprifoliaceae (honeysuckle) family utilized in traditional medical practices. This twining vine honeysuckle also is a much-sought ornamental, in part due to its dynamic flower coloration, which changes from white to gold during development. The molecular mechanism underlying dynamic flower coloration in L. japonica was elucidated by integrating whole genome sequencing, transcriptomic analysis and biochemical assays. Here, we report a chromosome-level genome assembly of L. japonica, comprising nine pseudochromosomes with a total size of 843.2 Mb. We also provide evidence for a whole-genome duplication event in the lineage leading to L. japonica, which occurred after its divergence from Dipsacales and Asterales. Moreover, gene expression analysis not only revealed correlated expression of the relevant biosynthetic genes with carotenoid accumulation, but also suggested a role for carotenoid degradation in L. japonica's dynamic flower coloration. The variation of flower color is consistent with not only the observed carotenoid accumulation pattern, but also with the release of volatile apocarotenoids that presumably serve as pollinator attractants. Beyond novel insights into the evolution and dynamics of flower coloration, the high-quality L. japonica genome sequence also provides a foundation for molecular breeding to improve desired characteristics. <<<
翻译
回到顶部