148 research outputs found
Moment closure approximations of susceptible-infected-susceptible epidemics on adaptive networks
No full textThe influence of people's individual responses to the spread of contagious phenomena, like the COVID-19 pandemic, is still not well understood. We investigate the Markovian Generalized Adaptive Susceptible-Infected-Susceptible (G-ASIS) epidemic model. The G-ASIS model comprises many contagious phenomena on networks, ranging from epidemics and information diffusion to innovation spread and human brain interactions. The connections between nodes in the G-ASIS model change adaptively over time, because nodes make decisions to create or break links based on the health state of their neighbors. Our contribution is fourfold. First, we rigorously derive the first-order and second-order mean-field approximations from the continuous-time Markov chain. Second, we illustrate that the first-order mean-field approximation fails to approximate the epidemic threshold of the Markovian G-ASIS model accurately. Third, we show that the second-order mean-field approximation is a qualitative good approximation of the Markovian G-ASIS model. Finally, we discuss the Adaptive Information Diffusion (AID) model in detail, which is contained in the G-ASIS model. We show that, similar to most other instances of the G-ASIS model, the AID model possesses a unique steady state, but that in the AID model, the convergence time toward the steady state is very large. Our theoretical results are supported by numerical simulations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Network Architectures and Service
Characteristics of Self-Citation in Journal of Natural Rubber Research 1988-1997: a Ten-Year Bibliometric Study
No full textAnalyses the extent of journal self-citation and author self-citation in the research articles and short communications published in Journal of Natural Rubber Research during 1988 to 1997. Results show that 53% of articles contained journal self-citations; the rate of journal self-citations per article ranges between 1 to 12; a high percentage of authors (61.4%) contributing articles to the journal cited themselves; a tendency is noticed for authors affiliated to the institution publishing the journal to cite the journal; the highest self-citing author is A. D. Roberts
From epidemics to information propagation: Striking differences in structurally similar adaptive network models
No full textThe continuous-time adaptive susceptible-infected-susceptible (ASIS) epidemic model and the adaptive information diffusion (AID) model are two adaptive spreading processes on networks, in which a link in the network changes depending on the infectious state of its end nodes, but in opposite ways: (i) In the ASIS model a link is removed between two nodes if exactly one of the nodes is infected to suppress the epidemic, while a link is created in the AID model to speed up the information diffusion; (ii) a link is created between two susceptible nodes in the ASIS model to strengthen the healthy part of the network, while a link is broken in the AID model due to the lack of interest in informationless nodes. The ASIS and AID models may be considered as first-order models for cascades in real-world networks. While the ASIS model has been exploited in the literature, we show that the AID model is realistic by obtaining a good fit with Facebook data. Contrary to the common belief and intuition for such similar models, we show that the ASIS and AID models exhibit different but not opposite properties. Most remarkably, a unique metastable state always exists in the ASIS model, while there an hourglass-shaped region of instability in the AID model. Moreover, the epidemic threshold is a linear function in the effective link-breaking rate in the AID model, while it is almost constant but noisy in the AID model.Intelligent SystemsElectrical Engineering, Mathematics and Computer Scienc
Middle of the (by)line: Examining hyperauthorship networks in the Human Genome Project
No full textThe era of big science promises rapid growth of scientific innovations and complex problem-solving, bringing forth the practice of doing science in large-scale collaborative effort rather than single author, solitary work. In disciplines such as genomics and high-energy physics, it is not uncommon that hyperauthorship phenomenon with the amount of authors soaring high from hundredth to thousandth. The purpose of this research is to explore the collaboration dynamics and the partial alphabetical author byline in one of the primary research article within the Human Genome Project (HGP). Using co-authorship network analysis, we find that middle authors play crucial roles in facilitating collaboration among previously unconnected authors as well as contributing to genetic sequencing efforts. Future work entails network analysis of all published works by HGP to comprehensively capture collaboration dynamics among multiple research centers.Open Restriction set for Item 107980 on 2018-10-22T16:13:30Z with date null by [email protected] by Jessica Cheng ([email protected]) on 2018-10-22T16:23:50Z
No. of bitstreams: 2
ASIS&T18_MiddleOfTheByline_final.pdf: 929023 bytes, checksum: ebc590c0a662502f696e162225dbca84 (MD5)
ASIST-MiddleOfByline-2018Poster.pdf: 8457527 bytes, checksum: ba5c6071140e590754f1547967626378 (MD5)Made available in DSpace on 2018-10-22T16:23:51Z (GMT). No. of bitstreams: 2
ASIS&T18_MiddleOfTheByline_final.pdf: 929023 bytes, checksum: ebc590c0a662502f696e162225dbca84 (MD5)
ASIST-MiddleOfByline-2018Poster.pdf: 8457527 bytes, checksum: ba5c6071140e590754f1547967626378 (MD5)
Previous issue date: 2018Goggin fundSmith fundOpe
Using information obtained through informetrics to address practical problems and to aid decision making Sponsored by: ASIS&T SIG/MET Panel committee: Judit Bar-Ilan i , Jonathan Levitt (corresponding author) ii
No full textABSTRACT This panel aims to inform participants of, and to stimulate interest in, the diverse ways in which the measurement of information (informetrics) is used in real-world applications. Its timeliness is indicated by the recent increase in interest amongst ASIS&T members in informetrics that culminated in the endorsement of the change of status of SIG/MET from a virtual SIG to fully functional ASIS&T SIG. The panelists, selected for their diverse experiences in informetrics, address a diversity of issues in the use of informetric information in real-world situations. The format of the panel is designed to encourage audience participation with the audience being encouraged to suggest issues for discussion
Spreading Processes over Adaptive Networks
No full textThe spreading process of diseases has been an important research topic for many years. It has profound effects on the development of human social behaviors. The underlying social network structure may change when individuals change their connection with other individuals in response to the epidemic. The classic susceptible-infected-susceptible (SIS) model is used to model the spread of an epidemic on a network, where all individuals are defined as nodes and the connections between the individuals are regarded as links. Besides the typical static network, the structure of the network can be related to the state of nodes (infected or susceptible) by link breaking and link creation processes. So the extended network, adaptive susceptible-infected-susceptible model (ASIS model) can be derived.To study the spreading process on static networks and adaptive networks, we use stochas- tic simulations and mean field approximations. We assume that the spreading process over the network is a continuous-time discrete-state Markov process. But most recent works use the discrete-time simulator, which is actually an approximation of the process. In this report, we extend a existing continuous-time simulator towards adaptive networks. This existing simulator is based on the Gillespie algorithm. We perform the simulations using both discrete-time Markov chain and continuous-time Markov process. And based on the simulation results, we demonstrate that the continuous-time simulator has a better performance than the discrete-time simulator on modeling both static SIS network and ASIS network with high accuracy.The second part of this work aims to study the characteristics of the ASIS network in the metastable state. We observe three possible states of the ASIS network: the endemic state, disease-free state and bistable state. The degree distribution of the graph follows a binomial distribution in some cases. By plenty of simulations with different parameters, we illustrate under what circumstances the degree distribution follows the binomial distribution.Electrical Engineering | Wireless Communication and Sensin
An initial exploration of the link relationship between UK university Web sites.
No full textAggregates of links are of interest to information scientists in the same way as citation counts are: as potential sources of data from which new knowledge can be mined. Builds on the recent discovery of a correlation between a Web link count measure and the research quality of British universities by applying a range of multivariate statistical techniques to counts of links between pairs of universities. This represents an initial attempt at developing an understanding of this phenomenon. Extracts plausible results. Also identifies outliers in the data by the techniques, some of which were verified by being tracked down to identifiable Web phenomena. This is an important outcome because successful anomaly identification is a precondition to more effective analysis of this kind of data. The identification of groupings is encouraging evidence that Web links between universities can be mined for significant results, although it is clear that more methodological development is needed, if any but the simplest patterns are to be extracted. Finally, based upon the types of patterns extracted, argues that none of the methods used are capable of fully analysing link structures on their own
Exterior view of Mission Santa Clara de Asis, 1861
No full textPhotograph of the exterior view of Mission Santa Clara de Asis, 1861. The mission is about three-stories tall and in dilapidated condition. Stucco from the church is pealing off. The tower, located to the left of the church, is approximately a story taller and in the same condition as the church. A fence separates the mission's courtyard from the street. A nearby building is visible in the background.; Picture file card reads: "Reproduced from Daguerreotype by Grant Jackson. This photograph should be dated as 1861, as in that year the Italian façade seen in photo CHS-7866 was built. In 1861, the roof of the church was extended to protect the side walls as seen in photo CHS-6188. Posts were set in to support the roof. In this same year, the Italian façade--brick veneer--was built."; "It was the intention of the padres to found another mission in pretty meadowland a few miles south of San Francisco Bay as soon as the San Francisco mission was well established. The mission of Santa Clara indeed was established only three months later on January 12, 1777. To the dismay of the missionaries, in six more months there arrived a large group of colonists from Mexico. The padres did their best to keep the mission and the pueblo separated, well knowing the detrimental influence of civilians on the neophytes. Ultimately, mission and pueblo grew into the twin cities of Santa Clara and San Jose. In 1784 the mission had to be abandoned because of damage from a great flood. A new site on higher ground was soon occupied, with the help of skilled artisans from the pueblo whose work gave the buildings a much more professional appearance. Yet this skill came to naught in 1818 when an earthquake effectively destroyed the mission again. With seemingly boundless energy the padres built a third time, with everything completed by 1825." -- unknown author
Gestión y Distribución de Aplicaciones en Grandes Organizaciones
No full textThis thesis describes first the general state of the art in Software Management and Distribution in large Organisations, entering then the specifics of CERN and its software management and distribution method for UNIX/Linux-based systems called ASIS. The advantages and shortcomings of ASIS in its state before 1997 are explained in detail. The redesign and rewrite of the ASIS software framework and its tools, for which the author spent 12 months at CERN, is the core part of the thesis. The main functionality enhancements include the design and implementation of a transaction-based system for validating changes to the ASIS software repository, and its fail-safe replication on local and remote sites. The new framework and these tools are currently in production at CERN and many other institutes
A Connectionist and Multivariate Approach to Science Maps: Som, Clustering and Mds Applied to Library & Information Science Research.
No full textThe visualization of scientific field structures is a classic of scientometric studies. This paper presents a domain analysis of the library and information science discipline based on author co-citation analysis (ACA) and journal cocitation analysis (JCA). The techniques used for map construction are the self-organizing map (SOM) neural
algorithm, Ward’s clustering method and multidimensional
scaling (MDS). The results of this study are compared with
similar research developed by Howard White and Katherine
McCain [1]. The methodologies used allow us to confirm that
the subject domains identified in this paper are, as well,
present in our study for the corresponding period. The appearance of studies pertaining to library science reveals
the relationship of this realm with information science.
Especially significant is the presence of the management on the journal maps. From a methodological standpoint, meanwhile, we would agree with those authors who consider
MDS, the SOM and clustering as complementary methods
that provide representations of the same reality from different analytical points of view. Even so, the MDS representation is the one offering greater possibilities for the structural representation of the clusters in a set of variables
- …
