1,721,066 research outputs found
Sacrifice Study, 2013
No full text130 romantic couples (N 260) from Amsterdam and surrounding, Netherlands. All participants were required to speak Dutch. Couples could participate in the study if they were together for longer than 4 months, if they had no children, and if they had a smartphone (for the experience sampling and diary parts). All couples were heterosexual, except for one homosexual couple. Participants’ age ranged from 18 to 43 years (M = 23.33, SD = 3.65). Over half of the participants (63.6%) were students, 34% were working full time, and 2.4% were both working and studying. Couples’ romantic involvement ranged from 4 months to 17 years (M = 34.13, SD = 29.01 months) and 34.8% of the couples were living together, of which a minority (2.4%) was married.
Couples came to the laboratory for an intake session, they were separated and asked to fill in some questionnaires. After this they were videotaped while discussing a situation of divergence of interests between them. We also assessed cortisol and testosterone before and after the conversation. After the conversation they watched the video of their conversation and provided some ratings about it.
At the end of the intake session they were given instructions about the experience sampling procedure. Each couple started the experience sampling on the Saturday following the intake session. For eight days (two Saturdays, two Sundays, one Monday, one Tuesday, one Thursday and one Friday), participants received six signals per day, approximately one signal every two hours, to ask them some questions (many of them regarding sacrifices – see also variables list)
Furthermore, each day, after 9.00 pm. participants performed a daily diary survey with general questions about their day.
Finally, one year later, couples were contacted again for a follow-up in which they replied to few questions.
The study was approved by the ethical board of the faculty of Behavioral and Movement Sciences of the VU Amsterdam
Mobile6TiSCH: a Simulator for 6TiSCH-based Industrial IoT Networks with Mobile Nodes
No full textThe Internet Engineering Task Force (IETF) has defined the 6TiSCH architecture to enable the Industrial Internet of Things (IIoT). While many industrial applications involve mobile devices (e.g., mobile robots or wearable devices carried by workers), 6TiSCH does not provide any mechanism to manage node mobility. However, recently, a Synchronized Single-hop Mul-tiple Gateway (SHMG) architecture has been proposed to allow an efficient management of mobile nodes in 6TiSCH networks. The SHMG architecture is quite flexible and can be customized to meet the requirements of different IIoT applications. However, find the appropriate configuration to guarantee the application requirements, may not be trivial. In this paper, we present Mobile6TiSCH, a simulation tool based on OMNeT ++, that implements the SHMG architecture. The proposed tool is general and allows to evaluate the Quality of Service (QoS) achieved by mobile nodes, in different scenarios. As such, it can be used to evaluate different solutions in a simulated environment before implementing them in practice. We describe the organization and implementation of Mobile6TiSCH and show the simulation results to display its effectiveness
Is Edge Computing Always Suitable for Image Analysis? An Experimental Analysis
No full textIn the era of Smart Cities, video surveillance stands as a pivotal tool for enhancing urban security, optimizing resource management, and improving the quality of urban life. When video surveillance is seamlessly integrated with image analysis systems, raw visual data are transformed into actionable insights, significantly enhancing the capability of Smart Cities to ensure public safety and optimize urban operations.
Image analysis systems mainly rely on the cloud: images are offloaded to a cloud infrastructure to be processed, analyzed and segmented for inference. The analysis of images in external systems, however, is not always recommended, due to privacy/security concerns, e.g., human action recognition. In this paper, we investigate the opportunity to adopt edge computing to implement such systems, where images are analyzed directly on-premises.
To investigate the suitability of this approach, we carried out an extensive experimentation using two large-scale Fed4Fire+ testbeds, namely, Grid'5000 and Virtual Wall. Specifically, we considered different cloud-edge configurations using different inference models, and evaluated the impact of those models on performance and resource utilization. Based on these results, we provide a set of guidelines for the adoption of different models depending on the requirements of the specific application
Energy-efficient Orchestration Strategies for Function-as-a-Service Platforms
No full textCommercial cloud computing platforms are seamlessly adopted to support many different types of applications, ensuring economic benefits to the application providers. Among the different solutions proposed by cloud providers, Function as a Service (FaaS) platforms are becoming very attractive, since they support lean and agile application packaging and management. However, the energy consumed by the many servers used to support FaaS poses economical and environmental challenges for the Cloud companies. To tackle such challenges, in this paper we design a framework to reduce energy consumption of FaaS platforms by consolidating container creation through active monitoring of the platform status. We implemented our solution on the OpenWhisk platform and carried out a performance evaluation using the Azure Dataset traces. Our experiments show an energy consumption reduction up to 46% with respect to the default resource orchestration of the OpenWhisk platform
Investigating the CoAP Congestion Control Strategies for 6TiSCH-Based IoT Networks
No full textThe Constrained Application Protocol (CoAP) is a RESTful protocol standardized by the IETF and widely used for IoT applications. CoAP includes a default congestion control algorithm to ensure efficient operation under high traffic conditions. Other congestion control algorithms for CoAP have been proposed and evaluated in the literature, including the very popular CoCoA algorithm. All these algorithms assume that the underlying wireless communication is regulated through the 802.15.4 CSMA-CA protocol. Today, many IoT systems are based on the 6TiSCH architecture that, instead, leverages the TSCH (Time Slotted Channel Hopping) mode of IEEE 802.15.4, i.e., a synchronous and time-slotted access protocol. In this paper we investigate, by simulation, the suitability of existing CoAP congestion-control algorithms to the 6TiSCH architecture. Our results show that the performance of the considered algorithms are strongly influenced by the Scheduling Function used to allocate communication resources to nodes. In addition, our analysis emphasizes that CoCoA does not provide a significant advantage over the default algorithm in 6TiSCH networks. We investigate the motivations for such a behavior and propose an optimized version of CoCoA, namely 6CoCoA, specifically tailored for 6TiSCH networks. 6CoCoA is able to provide up to a 15% improvement of the Transaction Delivery Ratio and up to a 25% reduction of the end-to-end Transaction Delay, when the network is congested
An Evaluation of the 6TiSCH Distributed Resource Management Mode
Full text linkThe IETF is currently defining the 6TiSCH architecture for the Industrial Internet of Things to ensure reliable and timely communication. 6TiSCH relies on the IEEE TSCH MAC protocol and defines different scheduling approaches for managing TSCH cells, including a distributed (neighbor-to-neighbor) scheduling scheme, where cells are allocated by nodes in a cooperative way. Each node leverages a Scheduling Function (SF) to compute the required number of cells, and the 6top (6P) protocol to negotiate them with neighbors. Currently, the Minimal Scheduling Function (MSF) is under consideration for standardization. However, multiple SFs are expected to be used in real deployments, in order to accommodate the requirements of different use cases. In this article, we carry out a comprehensive analysis of 6TiSCH distributed scheduling to assess its performance under realistic conditions. Firstly, we derive an analytical model to assess the 6P protocol, and we show that 6P transactions take a long time to complete and may also fail. Then, we evaluate the performance of MSF and other distributed SFs through simulations and real experiments. The results show that their performance is affected by the failure of 6P transactions and the instability of the routing protocol, which may lead to congestion from which the network is unable to recover. Finally, we propose a new SF (E-OTF) and show, through simulations and real experiments, that it can effectively improve the overall performance, by allowing nodes to quickly recover from congestion
Vulnerabilities of the 6P protocol for the Industrial Internet of Things : Impact analysis and mitigation
Full text linkThe 6TiSCH architecture defined by the IETF provides a standard solution for extending the Internet of Things (IoT) paradigm to industrial applications with stringent reliability and timeliness requirements. In this context, communication security is another crucial requirement, which is currently less investigated in the literature. In this article, we present a deep assessment of the security vulnerabilities of 6P, the protocol used for resource negotiation at the core of the 6TiSCH architecture. Specifically, we highlight two possible attacks against 6P, namely the Traffic Dispersion and the Overloading attacks. These two attacks effectively and stealthy alter the communication schedule of victim nodes and severely thwart network basic functionalities and efficiency, by specifically impacting network availability and energy consumption of victim nodes. To assess the impact of the attacks two analytical models have been defined, while, to demonstrate their feasibility, they have been implemented in Contiki-NG. The implementation has been used to quantitatively evaluate the impact of the two attacks by both simulations and measurements in a real testbed. Our results show that the impact of both attacks may be very significant. The impact, however, strongly depends on the position of the victim node(s) in the network and it is highly influenced by the dynamics of the routing protocol. We have investigated mitigation strategies to alleviate this impact and proposed an extended version of the Minimal Scheduling Function (MSF), i.e., the reference scheduling algorithm for 6TiSCH. This allows network nodes to early detect anomalies in their schedules possibly due to an Overloading attack, and thus curb the attack impact by appropriately revising their schedule. Funding details: 952652; Funding details: RIT17-0032; Funding details: Horizon 2020 Framework Programme, H2020; Funding details: VINNOVA; Funding details: Ministero dell’Istruzione, dell’Università e della Ricerca, MIUR; Funding text 1: The authors sincerely thank the anonymous reviewers and the Associate Editor for their insightful comments and suggestions, that have helped to improve the technical and editorial quality of the manuscript. The authors would also like to thank Gioele Carignani for his invaluable help in the implementation of the attacks on the Contiki-NG OS. This work was partially supported by the Italian Ministry of Education and Research (MIUR) in the framework of the CrossLab project (Departments of Excellence); by VINNOVA and the CelticNext project CRITISEC; by the H2020 project SIFIS-Home (Grant agreement 952652 ); and by the SSF project SEC4Factory (grant RIT17-0032 ).</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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