2,282 research outputs found
Familiarity-based Collaborative Team Recognition in Academic Social Networks
Collaborative teamwork is key to major scientific discoveries. However, the
prevalence of collaboration among researchers makes team recognition
increasingly challenging. Previous studies have demonstrated that people are
more likely to collaborate with individuals they are familiar with. In this
work, we employ the definition of familiarity and then propose MOTO
(faMiliarity-based cOllaborative Team recOgnition algorithm) to recognize
collaborative teams. MOTO calculates the shortest distance matrix within the
global collaboration network and the local density of each node. Central team
members are initially recognized based on local density. Then MOTO recognizes
the remaining team members by using the familiarity metric and shortest
distance matrix. Extensive experiments have been conducted upon a large-scale
data set. The experimental results show that compared with baseline methods,
MOTO can recognize the largest number of teams. The teams recognized by MOTO
possess more cohesive team structures and lower team communication costs
compared with other methods. MOTO utilizes familiarity in team recognition to
identify cohesive academic teams. The recognized teams are in line with
real-world collaborative teamwork patterns. Based on team recognition using
MOTO, the research team structure and performance are further analyzed for
given time periods. The number of teams that consist of members from different
institutions increases gradually. Such teams are found to perform better in
comparison with those whose members are from the same institution
The Ambivalence of Cultural Homophily: Field Positions, Semantic Similarities, and Social Network Ties in Creative Collectives
This paper utilizes a mixture of qualitative, formal, and statistical
socio-semantic network analyses to examine how cultural homophily works when
field logic meets practice. On the one hand, because individuals in similar
field positions are also imposed with similar cultural orientations, cultural
homophily reproduces objective field structure in intersubjective social
network ties. On the other hand, fields are operative in practice and to
accomplish pragmatic goals individuals who occupy different field positions
often join in groups, creatively reinterpret the field-imposed cultural
orientations, and produce cultural similarities alternative to the
position-specific ones. Drawing on these emergent similarities, the cultural
homophily mechanism might stimulate social network ties between members who
occupy not the same but different field positions, thus contesting fields. I
examine this ambivalent role of cultural homophily in two creative collectives,
each embracing members positioned closer to the opposite poles of the field of
cultural production. I find different types of cultural similarities to affect
different types of social network ties within and between the field positions:
Similarity of vocabularies stimulates friendship and collaboration ties within
positions, thus reproducing the field, while affiliation with the same cultural
structures stimulates collaboration ties between positions, thus contesting the
field. The latter effect is visible under statistical analysis of ethnographic
data, but easy to oversee in qualitative analysis of texts because informants
tend to flag conformity to their positions in their explicit statements. This
highlights the importance of mixed socio-semantic network analysis, both
sensitive to the local context and capable of unveiling the mechanisms
underlying the interplay between the cultural and the social.Comment: The latest version of this paper was accepted to Poetics in 201
The MODEST questions: challenges and future directions in stellar cluster research
We present a review of some of the current major challenges in stellar
cluster research, including young clusters, globular clusters, and galactic
nuclei. Topics considered include: primordial mass segregation and runaway
mergers, expulsion of gas from clusters, the production of stellar exotica seen
in some clusters (eg blue stragglers and extreme horizontal--branch stars),
binary populations within clusters, the black--hole population within stellar
clusters, the final parsec problem, stellar dynamics around a massive black
hole, and stellar collisions. The Modest Questions posed here are the outcome
of discussions which took place at the Modest-6A workshop held in Lund, Sweden,
in December, 2005. Modest-6A was organised as part of the activities of the
Modest Collaboration (see www.manybody.org for further details)Comment: 24 pages, no figures, accepted for publication in New Astronom
Plasma Edge Kinetic-MHD Modeling in Tokamaks Using Kepler Workflow for Code Coupling, Data Management and Visualization
A new predictive computer simulation tool targeting the development of the H-mode pedestal at the plasma edge in tokamaks and the triggering and dynamics of edge localized modes (ELMs) is presented in this report. This tool brings together, in a coordinated and effective manner, several first-principles physics simulation codes, stability analysis packages, and data processing and visualization tools. A Kepler workflow is used in order to carry out an edge plasma simulation that loosely couples the kinetic code, XGC0, with an ideal MHD linear stability analysis code, ELITE, and an extended MHD initial value code such as M3D or NIMROD. XGC0 includes the neoclassical ion-electron-neutral dynamics needed to simulate pedestal growth near the separatrix. The Kepler workflow processes the XGC0 simulation results into simple images that can be selected and displayed via the Dashboard, a monitoring tool implemented in AJAX allowing the scientist to track computational resources, examine running and archived jobs, and view key physics data, all within a standard Web browser. The XGC0 simulation is monitored for the conditions needed to trigger an ELM crash by periodically assessing the edge plasma pressure and current density profiles using the ELITE code. If an ELM crash is triggered, the Kepler workflow launches the M3D code on a moderate-size Opteron cluster to simulate the nonlinear ELM crash and to compute the relaxation of plasma profiles after the crash. This process is monitored through periodic outputs of plasma fluid quantities that are automatically visualized with AVS/Express and may be displayed on the Dashboard. Finally, the Kepler workflow archives all data outputs and processed images using HPSS, as well as provenance information about the software and hardware used to create the simulation. The complete process of preparing, executing and monitoring a coupled-code simulation of the edge pressure pedestal buildup and the ELM cycle using the Kepler scientific workflow system is described in this paper
Efficient Data Streaming Analytic Designs for Parallel and Distributed Processing
Today, ubiquitously sensing technologies enable inter-connection of physical\ua0objects, as part of Internet of Things (IoT), and provide massive amounts of\ua0data streams. In such scenarios, the demand for timely analysis has resulted in\ua0a shift of data processing paradigms towards continuous, parallel, and multitier\ua0computing. However, these paradigms are followed by several challenges\ua0especially regarding analysis speed, precision, costs, and deterministic execution.\ua0This thesis studies a number of such challenges to enable efficient continuous\ua0processing of streams of data in a decentralized and timely manner.In the first part of the thesis, we investigate techniques aiming at speeding\ua0up the processing without a loss in precision. The focus is on continuous\ua0machine learning/data mining types of problems, appearing commonly in IoT\ua0applications, and in particular continuous clustering and monitoring, for which\ua0we present novel algorithms; (i) Lisco, a sequential algorithm to cluster data\ua0points collected by LiDAR (a distance sensor that creates a 3D mapping of the\ua0environment), (ii) p-Lisco, the parallel version of Lisco to enhance pipeline- and\ua0data-parallelism of the latter, (iii) pi-Lisco, the parallel and incremental version\ua0to reuse the information and prevent redundant computations, (iv) g-Lisco, a\ua0generalized version of Lisco to cluster any data with spatio-temporal locality\ua0by leveraging the implicit ordering of the data, and (v) Amble, a continuous\ua0monitoring solution in an industrial process.In the second part, we investigate techniques to reduce the analysis costs\ua0in addition to speeding up the processing while also supporting deterministic\ua0execution. The focus is on problems associated with availability and utilization\ua0of computing resources, namely reducing the volumes of data, involving\ua0concurrent computing elements, and adjusting the level of concurrency. For\ua0that, we propose three frameworks; (i) DRIVEN, a framework to continuously\ua0compress the data and enable efficient transmission of the compact data in the\ua0processing pipeline, (ii) STRATUM, a framework to continuously pre-process\ua0the data before transferring the later to upper tiers for further processing, and\ua0(iii) STRETCH, a framework to enable instantaneous elastic reconfigurations\ua0to adjust intra-node resources at runtime while ensuring determinism.The algorithms and frameworks presented in this thesis contribute to an\ua0efficient processing of data streams in an online manner while utilizing available\ua0resources. Using extensive evaluations, we show the efficiency and achievements\ua0of the proposed techniques for IoT representative applications that involve a\ua0wide spectrum of platforms, and illustrate that the performance of our work\ua0exceeds that of state-of-the-art techniques
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