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Impact of autocorrelation on functional connectivity

Mohammad R. Arbabshirani, Eswar Damaraju, Ronald Phlypo, Sergey Plis, Elena Allen, Sai Ma, Daniel Mathalon, Adrian Preda, Jatin G. Vaidya, Tülay Adali, Vince D. Calhoun
2014 NeuroImage  
Although the impact of serial correlation (autocorrelation) in residuals of general linear models for fMRI time-series has been studied extensively, the effect of autocorrelation on functional connectivity  ...  To our knowledge this is the first work comprehensively investigating the effect of autocorrelation on functional connectivity estimates.  ...  Acknowledgments We would like to acknowledge the efforts of all parties responsible for designing and implementing the experiment, collecting the data, and facilitating the brain imaging that made this  ... 
doi:10.1016/j.neuroimage.2014.07.045 pmid:25072392 pmcid:PMC4253536 fatcat:oxskide3ifacvdige2w2dwppj4

Impact of sampling rate on statistical significance for single subject fMRI connectivity analysis

Oliver James, Hyunjin Park, Seong‐Gi Kim
2019 Human Brain Mapping  
While performing connectivity analysis in fMRI, the impact of the autocorrelation is largely ignored.  ...  In addition, temporal filtering, one of the crucial steps in preprocessing of functional magnetic resonance images, induces its own autocorrelation.  ...  In this study, we investigated the impact of the sampling rate on the functional connectivity analysis that accounts for the autocorrelation.  ... 
doi:10.1002/hbm.24600 pmid:31004386 pmcid:PMC6618018 fatcat:c3nkh2dtcbe55dxmbadytiq2di

Assessing dynamic functional connectivity in heterogeneous samples

B.C.L. Lehmann, S.R. White, R.N. Henson, Cam-CAN, L. Geerligs
2017 NeuroImage  
These methods are often based on a sliding-window analysis, which aims to capture how the brain's functional organization varies over the course of a scan.  ...  A B S T R A C T Several methods have been developed to measure dynamic functional connectivity (dFC) in fMRI data.  ...  Hill for his helpful comments on a draft of this manuscript. BL, SRW and RNH are supported by the UK Medical Research Council [Programme numbers U105292687  ... 
doi:10.1016/j.neuroimage.2017.05.065 pmid:28578129 pmcid:PMC5590721 fatcat:dv5aci3qdrd4nf6xukzkg44zpm

Assessing dynamic functional connectivity in heterogeneous samples [article]

Brieuc C L Lehmann, Simon R White, Richard N Henson, Linda Geerligs
2017 bioRxiv   pre-print
These methods are often based on a sliding-window analysis, which aims to capture how the brain's functional organization varies over the course of a scan.  ...  Several methods have been developed to measure dynamic functional connectivity (dFC) in fMRI data.  ...  Figure 3 illustrates the impact of neural autocorrelation on estimated dFC.  ... 
doi:10.1101/118968 fatcat:gk25bozsmbehzonzi65rwbtsuq

Effective degrees of freedom of the Pearson's correlation coefficient under autocorrelation

Soroosh Afyouni, Stephen M. Smith, Thomas E. Nichols
2019 NeuroImage  
We find that the severity of autocorrelation is highly dependent on spatial characteristics of brain regions, such as the size of regions of interest and the spatial location of those regions.  ...  Since fMRI time series are notoriously autocorrelated, the issue of biased standard errors - before or after Fisher's transformation - becomes vital in individual-level analysis of resting-state functional  ...  Acknowledgements We thank Andrew Zalesky at University of Melbourne, Mark Fiecas at University of Minnesota, Simon Schwab and Samuel Davenport at University of Oxford and Jeanette Mumford at University  ... 
doi:10.1016/j.neuroimage.2019.05.011 pmid:31158478 pmcid:PMC6693558 fatcat:5sb5v65mpbey7pp72fpjvzrxzm

Investigating the impact of autocorrelation on time-varying connectivity

Hamed Honari, Ann S. Choe, James J. Pekar, Martin A. Lindquist
2019 NeuroImage  
Although previous studies have shown that autocorrelation can negatively impact estimates of static functional connectivity, its impact on TVC estimates is not well known at this time.  ...  In recent years, a number of studies have reported on the existence of time-varying functional connectivity (TVC) in resting-state functional magnetic resonance imaging (rs-fMRI) data.  ...  NS104644 from the National Institute of Neurological Disorders and Stroke, and Craig H.  ... 
doi:10.1016/j.neuroimage.2019.04.042 pmid:31022568 pmcid:PMC6684286 fatcat:yb77aot2bjaxnfzugmdl6rn5lq

A Markov Model of Server to Client IP Traffic in First Person Shooter Games

P. A. Branch, A. L. Cricenti, G. J. Armitage
2008 2008 IEEE International Conference on Communications  
In part this has been driven by a desire to properly simulate the network impact of highly interactive online game genres such as the first person shooter (FPS).  ...  Past work has dealt with packet size and packet interarrival times without consideration of packet size autocorrelations.  ...  Phases of game-play and game traffic There are roughly three different phases of interaction between client and server that impact on network traffic. • A client initially connects to the server, and receives  ... 
doi:10.1109/icc.2008.1070 dblp:conf/icc/BranchCA08 fatcat:byiab6basnggzjlbr7vgzghhoq

Spatial Effects of Urban-Rural Ditch Connectivity Gradient Changes on Water Quality to Support Ditch Optimization and Management

Chunqi Qiu, Yufeng Li, Alan L. Wright, Cheng Wang, Jiayi Xu, Shiwei Zhou, Wanchun Huang, Yanhui Wu, Yinglei Zhang, Hongyu Liu
2021 Sustainability  
The connectivity of ditches can have great impacts on nutrient migration and transformations.  ...  This paper considered ditch connectivity and water quality indicators comprehensively, using spatial autocorrelation and geographically weighted regression (GWR) models, to analyze the impact of ditch  ...  Conflicts of Interest: The authors declare no conflict of interest.  ... 
doi:10.3390/su13158329 fatcat:v5f2rzmvyrexlbkj736lmjdsry

Effective Degrees of Freedom of the Pearson's Correlation Coefficient under Autocorrelation [article]

Soroosh Afyouni, Stephen M. Smith, Thomas E. Nichols
2018 bioRxiv   pre-print
We find that the severity of autocorrelation is highly dependent on spatial characteristics of brain regions, such as the size of regions of interest and the spatial location of those regions.  ...  Since fMRI time series are notoriously autocorrelated, the issue of biased standard errors -- before or after Fisher's transformation -- becomes vital in individual-level analysis of resting-state functional  ...  Effect of Autocorrelation Correction on Functional Connectivity The copyright holder for this preprint . http://dx.doi.org/10.1101/453795 doi: bioRxiv preprint first posted online Oct. 25, 2018; connection  ... 
doi:10.1101/453795 fatcat:gyp2mq6fkvd4pgseazu4zxrjma

Temporal downscaling: a comparison between artificial neural network and autocorrelation techniques over the Amazon Basin in present and future climate change scenarios

David Mendes, José A. Marengo
2009 Theoretical and Applied Climatology  
This paper introduces an application of temporal neural networks for downscaling global climate model output and autocorrelation functions.  ...  The performance in downscaling of the temporal neural network was compared to that of an autocorrelation statistical downscaling model with emphasis on its ability to reproduce the observed climate variability  ...  Therefore, we can say that our autocorrelation function will depend on the time difference and not some absolute time.  ... 
doi:10.1007/s00704-009-0193-y fatcat:5k4i5p3xubb2nmdzppe7ydzkku

Traffic Forecasting for Monitoring in Computer Networks using Time Series

Henrique Dornel, Eliane da Silva Christo, Kelly Alonso Costa, Danilo Pinto Moreira de Souza
2019 International Journal of Advanced Engineering Research and Science  
The objective of this work is to monitoring the connection of users to network -based applications, including resource availability and network stability of a Brazilian educational institute.  ...  This paper presents a study of data traffic forecasting on a computer network, by using known approaching methods for Time Series analysis.  ...  autocorrelation functions for the input and output series For both input and output traffic, the sinusoidal behavior of the autocorrelation function and a peak in the partial autocorrelation function  ... 
doi:10.22161/ijaers.6727 fatcat:qncde2lixvaudn5u2p6a2a4npu

The Impact of Persistence Length on the Communication Efficiency of Microtubules and CNTs [chapter]

Stephen F. Bush, Sanjay Goel
2009 Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering  
This behavior depends strongly on the alignment of bond segments and filaments, which in turn depends on the persistence length of the tubes.  ...  Persistence length is also important in analyzing other structures such as DNA; however, the focus in this paper is on nanotube structures and microtubules.  ...  (3) The autocorrelation of one of the tube's angles is shown in Figure 3 .  ... 
doi:10.1007/978-3-642-04850-0_1 fatcat:xhrfoabekbhr3npbhjkvuhcfcu

Spatial Autocorrelation, Dispersal and the Maintenance of Source-Sink Populations [chapter]

T. H. Keitt
2003 Ecological Studies  
I explore the in uence of spatial autocorrelation in habitat quality on the survival of model populations. Dispersal is modeled as Markov transitions between patches.  ...  The e ect of spatial autocorrelation was relatively weak, but interacted with dispersal distance.  ...  Acknowledgments The support of the Santa Fe Institute is gratefully acknowledged.  ... 
doi:10.1007/978-3-662-05238-9_13 fatcat:carx6dv5bfhjdo4inzsqtlcn7m

Experimental characterization of mechanical vibrations and acoustical noise generated by defective automotive wheel hub bearings

Eduardo Rubio, Juan C. Jáuregui
2012 Procedia Engineering  
The results of the various methods are compared and it was found that most of the methods used in this work are well suited for the analysis.  ...  In this paper a series of in-situ test with defective and healthy wheel hub bearings were conducted.  ...  Acknowledgements The authors wish to acknowledge financial assistance from the Mexican National Council for Science and Technology (CONACyT) and the Government of Aguascalientes.  ... 
doi:10.1016/j.proeng.2012.04.178 fatcat:mhumeudgbbejrirge2eaj256cu

Autocorrelation of gene frequencies under isolation by distance

G Barbujani
1987 Genetics  
The autocorrelation coefficient of gene frequencies at a given distance is a direct function of the kinship at that distance, and an inverse function of the standardized gene frequency variance, Fst.  ...  Spatial autocorrelation statistics are used for description of geographic variation of gene frequencies, but the relationship of these indices with the parameters describing the genetic structure of populations  ...  Contribution 639 in Ecology and Evolution from the State University of New York at Stony Brook.  ... 
pmid:3428574 pmcid:PMC1203249 fatcat:pbruws4lb5gphm5mxggm4rymnu
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