214 Using Interictal Multivariate Granger Causality to Detect Epileptogenic Hubs

Neurosurgery ◽  
2017 ◽  
Vol 64 (CN_suppl_1) ◽  
pp. 258-258
Author(s):  
David P Darrow ◽  
Theoden Netoff
Keyword(s):  
Granger Causality ◽  
Information Exchange ◽  
Time Windows ◽  
Directional Coupling ◽  
Recorded Data ◽  
Influential Nodes ◽  
Noise Nodes ◽  
Seizure Localization ◽  
Frequency Basis ◽  
Over Time

Abstract INTRODUCTION Surgical localization of epileptogenic networks requires significant intensive-care stays and facilitation of seizures for visual inspection. Multivariate Granger Causality (MVGC) provides a method of calculating the directional influence from each node to every other node during interictal data before seizures are facilitated after implantation of electrodes. MVGC is an efficient method of detecting biological coupling and has been shown to be robust against noise. Nodes identified as influential by MVGC have recently been shown to correlate with predicted seizure zones. METHODS Electrocorticography was examined and analyzed for five patients undergoing seizure localization surgery. Used ECOG channels were sampled at greater than 1.5 KHz for all patients. Model estimation was performed, and MVGC was used to calculate patterns of directional coupling over 100 second time windows. MVGC was performed on entire stays for two patients and on subsampled data for 3 patients. Coupling was also examined in the frequency domain to establish frequency basis of information exchange. Comparisons were made after blinded analysis was complete with seizure nodes identified by epileptologists. RESULTS >Five patients were included with more than 12 weeks of recorded data. MVGC adjacency matrices from interictal data over time from each patient revealed significant dominance by few nodes (average 1.8). Coupling changed little over time with highly accurate reconstructions after an average of 184 minutes when compared to the average matrix over the entire stay. On comparison to seizure onset nodes determined by epileptologist, the analysis found concordance 92.1% of the time with high significance compared to randomly selected channels (P < 0.00001). CONCLUSION MVGC is a method of detecting directional coupling in ECOG recordings. Previous and current work suggests that influential nodes during interictal data may predict epileptogenic hubs. Data collection may only require a few hours to reproduce the predicted influential nodes, potentially dramatically reducing the required length of stay.

scholarly journals Sars-Cov-2 in Argentina: Lockdown, Mobility, and Contagion

2020 ◽  
Author(s):  
Juan M.C. Larrosa
Keyword(s):  
Panel Data ◽  
Granger Causality ◽  
Random Effects ◽  
Social Costs ◽  
Political Discussion ◽  
Fixed And Random Effects ◽  
The World ◽  
Causality Tests ◽  
Granger Causality Tests ◽  
Over Time

AbstractThere is a debate in Argentina about the effectiveness of mandatory lockdown measures in containing COVID-19 that lasts five months making it one of the longest in the World. The population effort to comply the lockdown has been decreasing over time given the economic and social costs that it entails. We contributes by analyzing the Argentinian case through information of mobility and contagion given answers to recurrent questions on these topics. This paper aims to fill the gap in the literature by assessing the effects of lockdown measures and the regional relaxation on the numbers of rate of new infections. We also respond to issues of internal political discussion on regional contagion and the effect of marches and unexpected crowd events. We use pool, fixed and random effects panel data modeling and Granger causality tests identifying relations between mobility and contagion. Our results show that lockdown in Argentina has been effective in reducing the mobility but not in way that reduces the rate of contagion. Strict lockdown seems to be effective in short periods of time and by extend it without complementary measures loss effectiveness. Contagion rate seems to be discretely displaced in time and resurging amidst slowly increasing in mobility.

The Enterprise 2.0 Organization

2010 ◽  
pp. 44-56 ◽  
Author(s):  
Nadira Ali
Keyword(s):  
Web 2.0 ◽  
Information Exchange ◽  
Enterprise 2.0 ◽  
Web 2.0 Technologies ◽  
Global Business ◽  
New Era ◽  
Current Trends ◽  
Collaboration And Communication ◽  
Internet Revolution ◽  
Over Time

The implementation of Web 2.0 technologies in organizations ushers in a new era of collaboration and communication for enterprises. Enterprise 2.0 is the term that has emerged to describe the organization’s embrace of Web 2.0 technologies. This chapter examines the current trends and impact of Web 2.0 on organizations, managers, the workforce, and information exchange within and across companies. This phenomenon is expected to bring another wave of change to organizations that some believe could be on the magnitude of that experienced during the Internet revolution. These technological advancements do not come without challenges. Security, privacy, ethics, and legal considerations all play a major role in how these technologies develop over time. The time has come, however, for companies to begin to determine strategies for utilizing these technologies in order to remain competitive in the global business arena.

scholarly journals A Grid-Based Genetic Approach to Solving the Vehicle Routing Problem with Time Windows

2019 ◽  
Vol 9 (18) ◽  
pp. 3656 ◽  
Author(s):  
Marco Antonio Cruz-Chávez ◽  
Abelardo Rodríguez-León ◽  
Rafael Rivera-López ◽  
Martín H. Cruz-Rosales
Keyword(s):  
Genetic Algorithm ◽  
Vehicle Routing ◽  
Vehicle Routing Problem ◽  
Information Exchange ◽  
Time Windows ◽  
Optimization Procedure ◽  
Virtual Private Network ◽  
Routing Problem ◽  
Private Network ◽  
Grid Based

This paper describes one grid-based genetic algorithm approach to solve the vehicle routing problem with time windows in one experimental cluster MiniGrid. Clusters used in this approach are located in two Mexican cities (Cuernavaca and Jiutepec, Morelos) securely communicating with each other since they are configured as one virtual private network, and its use as a single set of processors instead of isolated groups allows one to increase the computing power to solve complex tasks. The genetic algorithm splits the population of candidate solutions in several segments, which are simultaneously mutated in each process generated by the MiniGrid. These mutated segments are used to build a new population combining the results produced by each process. In this paper, the MiniGrid configuration scheme is described, and both the communication latency and the speedup behavior are discussed. Experimental results show one information exchange reduction through the MiniGrid clusters as well as an improved behavior of the evolutionary algorithm. A statistical analysis of these results suggests that our approach is better as a combinatorial optimization procedure as compared with other methods.

scholarly journals Feature integration within discrete time windows

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Leila Drissi-Daoudi ◽  
Adrien Doerig ◽  
Michael H. Herzog
Keyword(s):  
Computational Model ◽  
Discrete Time ◽  
Time Windows ◽  
Temporal Integration ◽  
Sensory Information ◽  
Stimulus Onset ◽  
Feature Integration ◽  
Spatio Temporal ◽  
The Individual ◽  
Over Time

Abstract Sensory information must be integrated over time to perceive, for example, motion and melodies. Here, to study temporal integration, we used the sequential metacontrast paradigm in which two expanding streams of lines are presented. When a line in one stream is offset observers perceive all other lines to be offset too, even though they are straight. When more lines are offset the offsets integrate mandatorily, i.e., observers cannot report the individual offsets. We show that mandatory integration lasts for up to 450 ms, depending on the observer. Importantly, integration occurs only when offsets are presented within a discrete window of time. Even stimuli that are in close spatio-temporal proximity do not integrate if they are in different windows. A window of integration starts with stimulus onset and integration in the next window has similar characteristics. We present a two-stage computational model based on discrete time windows that captures these effects.

scholarly journals Story Tracker: Incremental visual text analytics of news story development

2013 ◽  
Vol 12 (3-4) ◽  
pp. 308-323 ◽  
Author(s):  
Miloš Krstajić ◽  
Mohammad Najm-Araghi ◽  
Florian Mansmann ◽  
Daniel A Keim
Keyword(s):  
Visual Analytics ◽  
Time Windows ◽  
Clustering Algorithms ◽  
Temporal Analysis ◽  
Online News ◽  
Full Detail ◽  
News Story ◽  
The Past ◽  
Split And Merge ◽  
Over Time

Online news sources produce thousands of news articles every day, reporting on local and global real-world events. New information quickly replaces the old, making it difficult for readers to put current events in the context of the past. The stories about these events have complex relationships and characteristics that are difficult to model: they can be weakly or strongly related or they can merge or split over time. In this article, we present a visual analytics system for temporal analysis of news stories in dynamic information streams, which combines interactive visualization and text mining techniques to facilitate the analysis of similar topics that split and merge over time. Text clustering algorithms extract stories from online news streams in consecutive time windows and identify similar stories from the past. The stories are displayed in a visualization, which (1) sorts the stories by minimizing clutter and overlap from edge crossings, (2) shows their temporal characteristics in different time frames with different levels of detail, and (3) allows incremental updates of the display without recalculating the past data. Stories can be interactively filtered by their duration and connectivity in order to be explored in full detail. To demonstrate the system’s capabilities for detailed dynamic text stream exploration, we present a use case with real news data about the Arabic Uprising in 2011.

Measures of node centrality in mobile social networks

2015 ◽  
Vol 26 (09) ◽  
pp. 1550107 ◽  
Author(s):  
Zhenxiang Gao ◽  
Yan Shi ◽  
Shanzhi Chen
Keyword(s):  
Social Networks ◽  
Social Relations ◽  
Human Mobility ◽  
Graph Model ◽  
Information Propagation ◽  
Mobile Social Networks ◽  
Mobility Patterns ◽  
Centrality Metrics ◽  
Influential Nodes ◽  
Over Time

Mobile social networks exploit human mobility and consequent device-to-device contact to opportunistically create data paths over time. While links in mobile social networks are time-varied and strongly impacted by human mobility, discovering influential nodes is one of the important issues for efficient information propagation in mobile social networks. Although traditional centrality definitions give metrics to identify the nodes with central positions in static binary networks, they cannot effectively identify the influential nodes for information propagation in mobile social networks. In this paper, we address the problems of discovering the influential nodes in mobile social networks. We first use the temporal evolution graph model which can more accurately capture the topology dynamics of the mobile social network over time. Based on the model, we explore human social relations and mobility patterns to redefine three common centrality metrics: degree centrality, closeness centrality and betweenness centrality. We then employ empirical traces to evaluate the benefits of the proposed centrality metrics, and discuss the predictability of nodes' global centrality ranking by nodes' local centrality ranking. Results demonstrate the efficiency of the proposed centrality metrics.

scholarly journals Hospitals’ adoption of intra-system information exchange is negatively associated with inter-system information exchange

2018 ◽  
Vol 25 (9) ◽  
pp. 1189-1196 ◽  
Author(s):  
Joshua R Vest ◽  
Kosali Simon
Keyword(s):  
Health System ◽  
Health Information ◽  
Information Exchange ◽  
Health Information Exchange ◽  
American Hospital ◽  
Organizational Information ◽  
System Information ◽  
Types Of Information ◽  
The Relationship ◽  
Over Time

Abstract Introduction U.S. policy on interoperable HIT has focused on increasing inter-system (ie, between different organizations) health information exchange. However, interoperable HIT also supports the movement of information within the same organization (ie, intra-system exchange). Methods We examined the relationship between hospitals’ intra- and inter-system information exchange capabilities among health system hospitals included in the 2010-2014 American Hospital Association’s Annual Health Information Technology Survey. We described the factors associated with hospitals that adopted more intra-system than inter-system exchange capability, and explored the extent of new capability adoption among hospitals that reported neither intra- or inter-system information capabilities at baseline. Results The prevalence of exchange increased over time, but the adoption of inter-system information exchange was slower; when hospitals adopt information exchange, adoption of intra-system exchange was more common. On average during our study period, hospitals could share 4.6 types of information by intra-system exchange, but only 2.7 types of information by inter-system exchange. Controlling for other factors, hospitals exchanged more types of information in an intra-system manner than inter-system when the number of different inpatient EHR vendors in use in health system is larger. Conclusion Consistent with the U.S. goals for more widely accessible patient information, hospitals’ ability to share information has increased over time. However, hospitals are prioritizing within-organizational information exchange over exchange between different organizations. If increasing inter-system exchanges is a desired goal, current market incentives and government policies may be insufficient to overcome hospitals’ motivations for pursuing an intra-system-information-exchange-first strategy.

scholarly journals Evaluation of intra-articular injection of bupivacaine with morphine or methylprednisolone or alone on pain after knee arthroscopy

2020 ◽  
pp. 314-322
Keyword(s):  
Side Effects ◽  
Pain Intensity ◽  
Repeated Measures ◽  
Knee Arthroscopy ◽  
Sedative Effect ◽  
Visual Analog Scales ◽  
Repeated Measures Analysis ◽  
Recorded Data ◽  
Spss Software ◽  
Over Time

Background and Aim: Knee arthroscopy is used to diagnose and treat intra-articular lesions. Controlling acute pain after arthroscopy requires the use of a method with the least side effects and the most efficiency. The aim of this study was to compare the sedative effect after intra-articular injection of bupivacaine combination with morphine or methylprednisolone or alone in knee arthroscopy. Materials and Methods: In this study clinical-randomized three-blind trial, 99 volunteer patients with knee arthroscopy were randomly divided into three groups: 1. Bupivacaine (0.5%), 2. Morphine (5 mg)+ bupivacaine (0.5%) and 3. Methylprednisolone (40 mg) + bupivacaine (0.5%). At the end of the operation, drugs were injected intra-articular and the amount of postoperative pain was evaluated and recorded based on visual analog scales 6, 12, 18, and 24 hours after injection. Also, receiving the injected analgesic within 24 hours, was recorded. Data were analyzed using SPSS software and repeated measures analysis of variance. Results: In all three groups, the pain intensity decreased significantly over time. The pain intensity of the methylprednisolone + bupivacaine and morphine+bupivacaine group was the similar, at different postoperative periods, but the pain intensity of these groups was significantly lower than the control. Also, consumption of the analgesics was significantly reduced in methylprednisolone+bupivacaine group compared to the two other groups. Conclusion: The results of this study showed that intra-articular injection of methylprednisolone + bupivacaine and morphine+bupivacaine was more effective than bupivacaine alone in reducing pain and the need for injectable analgesia.

scholarly journals Penerapan Keamanan Penyampaian Informasi Melalui Citra dengan Kriptografi Rijndael dan Steganografi LSB

2016 ◽  
Vol 3 (3) ◽  
pp. 228
Author(s):  
Bonifacius Vicky Indriyono
Keyword(s):  
Information Technology ◽  
Information Exchange ◽  
Human Life ◽  
Least Significant Bit ◽  
Media Images ◽  
Confidential Information ◽  
Science And Art ◽  
The Media ◽  
Cryptographic Techniques ◽  
Over Time

Komunikasi telah menjadi bagian dari kehidupan manusia dan menjadi hal yang sangat penting seiring dengan berjalannya waktu. Dalam proses komunikasi, banyak terjadi kegiatan pertukaran informasi. Ada kalanya informasi yang dipertukarkan tersebut bersifat penting dan rahasia sehingga keberadaannya tidak boleh diketahui oleh pihak yang tidak berkepentingan. Dengan berkembangnya teknologi informasi, banyak cara yang dilakukan agar kerahasiaan informasi tersebut dapat terjaga agar tidak jatuh ke tangan pihak-pihak yang tidak berkepentingan. Kriptografi merupakan kajian ilmu dan seni untuk menjaga suatu pesan dan meningkatkan aspek keamanan informasi. Selain menggunakan teknik kriptografi, menjaga kerahasiaan informasi juga dapat dilakukan dengan menggunakan metode steganografi, dimana dalam metode ini informasi yang akan dikirimkan disisipkan melalui sebuah media (gambar, musik, suara, video). Dalam penelitian ini, peneliti merancang sebuah aplikasi dengan menerapkan kombinasi steganografi teknik Least Significant Bit untuk menyisipkan informasi pesan dalam media Gambar bitmap 24 bit dan kriptografi Rijndael yang digunakan untuk melakukan enkripsi terhadap gambar bitmap sehingga informasi pesan dapat diamankan dari pihak-pihak yang tidak berkepentingan.Communication has been a part of human life and become very important over time. In the process of communication, a lot going on information exchange. There are times when the information exchanged is important and so secret that its existence should not be known by unauthorized parties. With the development of information technology, many ways in which the confidentiality of the information that can be maintained in order not to fall into the hands of parties who are not interested. Cryptography is the study of science and art to keep a message and to improve aspects of the security of information. In addition to using cryptographic techniques, confidential information can also be done by using steganography, which in this method of information to be transmitted is inserted through a media (images, music, sound, and video). In this study, researchers designed an application by applying a combination of Least Significant Bit steganography techniques to insert messages in the media information 24 bit bitmap images and Rijndael cryptography is used to encrypt the message bitmap image so that information can be secured from the parties who are not interested.

scholarly journals A unified framework for dissecting the effects of common signals on functional and effective connectivity analyses: power, coherence, and Granger causality

2017 ◽  
Author(s):  
Dror Cohen ◽  
Naotsugu Tsuchiya
Keyword(s):  
Granger Causality ◽  
Effective Connectivity ◽  
Reference Electrode ◽  
Mathematical Framework ◽  
Connectivity Analysis ◽  
Unified Framework ◽  
Special Cases ◽  
Recorded Data ◽  
The Common ◽  
Common Signal

AbstractWhen analyzing neural data it is important to consider the limitations of the particular experimental setup. An enduring issue in the context of electrophysiology is the presence of common signals. For example a non-silent reference electrode adds a common signal across all recorded data and this adversely affects functional and effective connectivity analysis. To address the common signals problem, a number of methods have been proposed, but relatively few detailed investigations have been carried out. We address this gap by analyzing local field potentials recorded from the small brains of fruit flies. We conduct our analysis following a solid mathematical framework that allows us to make precise predictions regarding the nature of the common signals. We demonstrate how a framework that jointly analyzes power, coherence and quantities from the Granger causality framework allows us to detect and assess the nature of the common signals. Our analysis revealed substantial common signals in our data, in part due to a non-silent reference electrode. We further show that subtracting spatially adjacent signals (bipolar rereferencing) largely removes the effects of the common signals. However, in some special cases this operation itself introduces a common signal. The mathematical framework and analysis pipeline we present can readily be used by others to detect and assess the nature of the common signals in their data, thereby reducing the chance of misinterpreting the results of functional and effective connectivity analysis.

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