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Publications

2017

Consumers' attitude toward Facebook advertising

Authors
Ferreira, F; Barbosa, B;

Publication
International Journal of Electronic Marketing and Retailing

Abstract
This paper aims to provide a closer look at consumers' attitude toward Facebook advertising by providing a comparison between attitude toward brand posts and ads, a topic that has been disregarded in the extant literature. It also considers the relationship with the users' ad avoidance and electronic word-of-mouth communication. An exploratory quantitative analysis was performed by means of a structured self-administered questionnaire. 385 individuals aged between 18 and 44 participated in the study. The results include evidence on respondents' more favourable attitude toward brand posts than toward Facebook ads. Moreover, ads are considered more annoying by those who spend more time on Facebook. These results help shed the light on how Facebook users handle ads and brand posts, offering some clues for a more effective social media marketing strategy. Copyright © 2017 Inderscience Enterprises Ltd.

2017

Permutations of functional magnetic resonance imaging classification may not be normally distributed

Authors
Al Rawi, MS; Freitas, A; Duarte, JV; Cunha, JP; Castelo Branco, M;

Publication
STATISTICAL METHODS IN MEDICAL RESEARCH

Abstract
A fundamental question that often occurs in statistical tests is the normality of distributions. Countless distributions exist in science and life, but one distribution that is obtained via permutations, usually referred to as permutation distribution, is interesting. Although a permutation distribution should behave in accord with the central limit theorem, if both the independence condition and the identical distribution condition are fulfilled, no studies have corroborated this concurrence in functional magnetic resonance imaging data. In this work, we used Anderson-Darling test to evaluate the accordance level of permutation distributions of classification accuracies to normality expected under central limit theorem. A simulation study has been carried out using functional magnetic resonance imaging data collected, while human subjects responded to visual stimulation paradigms. Two scrambling schemes are evaluated: the first based on permuting both the training and the testing sets and the second on permuting only the testing set. The results showed that, while a normal distribution does not adequately fit to permutation distributions most of the times, it tends to be quite well acceptable when mean classification accuracies averaged over a set of different classifiers is considered. The results also showed that permutation distributions can be probabilistically affected by performing motion correction to functional magnetic resonance imaging data, and thus may weaken the approximation of permutation distributions to a normal law. Such findings, however, have no relation to univariate/univoxel analysis of functional magnetic resonance imaging data. Overall, the results revealed a strong dependence across the folds of cross-validation and across functional magnetic resonance imaging runs and that may hinder the reliability of using cross-validation. The obtained p-values and the drawn confidence level intervals exhibited beyond doubt that different permutation schemes may beget different permutation distributions as well as different levels of accord with central limit theorem. We also found that different permutation schemes can lead to different permutation distributions and that may lead to different assessment of the statistical significance of classification accuracy.

2017

Addressing Facts and Gaps in the Phenolics Chemistry of Winery By-Products

Authors
Machado, NFL; Dominguez Perles, R;

Publication
MOLECULES

Abstract
Grape and wine phenolics display a noticeable structural diversity, encompassing distinct compounds ranging from simple molecules to oligomers, as well as polymers usually designated as tannins. Since these compounds contribute critically to the organoleptic properties of wines, their analysis and quantification are of primordial importance for winery industry operators. Besides, the occurrence of these compounds has been also extensively described in winery residues, which have been pointed as a valuable source of bioactive phytochemicals presenting potential for the development of new added value products that could fit the current market demands. Therefore, the cumulative knowledge generated during the last decades has allowed the identification of the most promising compounds displaying interesting biological functions, as well as the chemical features responsible for the observed bioactivities. In this regard, the present review explores the scope of the existing knowledge, concerning the compounds found in these winery by-products, as well as the chemical features presumably responsible for the biological functions already identified. Moreover, the present work will hopefully pave the way for further actions to develop new powerful applications to these materials, thus, contributing to more sustainable valorization procedures and the development of newly obtained compounds with enhanced biological properties.

2017

Exploring SDN to Deploy Flexible Sampling-Based Network Monitoring

Authors
da Silva, CP; Lima, SR; Silva, JMC;

Publication
NEW2AN

Abstract
In recent years we witnessed the arrival of new trends, such as server virtualization and cloud services, an increasing number of mobile devices and online contents, leading the networking industry to deliberate about how traditional network architectures can be adapted or even deciding if a new perspective for them should be taken. SDN (Software-Defined Networking) emerged under this framing, opening a road for new developments due to the centralized logic control and view of the network, the decoupling of data and control planes, and the abstraction of the underlying network infrastructure from the applications. Although firstly oriented to packet switching, network measurements have also emerged as one promising field for SDN, as its flexibility enables programmable measurements, allowing a SDN controller to manage measurement tasks concurrently at multiple spatial and temporal scales. In this context, this paper is focused on exploring the SDN architecture and components for supporting the flexible selection and configuration of network monitoring tasks that rely on the use of traffic sampling. The aim is to take advantage of the integrated view of SDN controllers to apply and configure appropriate sampling techniques in network measurement points according to the requirements of specific measurement tasks. Through SDN, flexible and service-oriented configuration of network monitoring can be achieved, allowing also to improve the trade-off between accuracy and overhead of the monitoring process. In this way, this study, examining relevant SDN elements and solutions for deploying this monitoring paradigm, provides useful insights to enhance the programmability and efficiency of sampling-based network monitoring.

2017

Worst-Case Bound Analysis for the Time-Critical MAC behaviors of IEEE 802.15.4e

Authors
Kurunathan, H; Severino, R; Koubaa, A; Tovar, E;

Publication
2017 IEEE 13TH INTERNATIONAL WORKSHOP ON FACTORY COMMUNICATION SYSTEMS (WFCS 2017)

Abstract
With an advancement towards the paradigm of Internet of Things (IoT), in which every device will be interconnected and communicating with each other, the field of wireless sensor networks has helped to resolve an ever-growing demand in meeting deadlines and reducing power consumption. Among several standards that provide support for IoT, the recently published IEEE 802.15.4e protocol is specifically designed to meet the QoS requirements of industrial applications. IEEE 802.15.4e provides five Medium-Access Control (MAC) behaviors, including three that target time-critical applications: Deterministic and Synchronous Multichannel Extension (DSME); Time Slotted Channel Hopping (TSCH) and Low Latency Deterministic Network (LLDN). However, the standard and the literature do not provide any worst-case bound analysis of these behaviors, thus it is not possible to effectively predict their timing performance in an application and accurately devise a network in accordance to such constraints. This paper fills this gap by contributing network models for the three time-critical MAC behaviors using Network Calculus. These models allow deriving the worst-case performance of the MAC behaviors in terms of delay and buffering requirements. We then complement these results by carrying out a thorough performance analysis of these MAC behaviors by observing the impact of different parameters.

2017

An application to enrich the study of Auditory Emotion Recognition

Authors
Rodrigues, R; Mendes, AJ; Carneiro, D; Amorim, M; Pinheiro, AP; Novais, P;

Publication
2017 13TH INTERNATIONAL CONFERENCE ON INTELLIGENT ENVIRONMENTS (IE 2017)

Abstract
The ability to recognize emotions in spoken words is central in human communication and social relationships. When studying one's ability to perceive emotions, the standard paradigm is to have listeners choose which one of several emotion words best characterizes linguistically neutral utterances made by actors attempting to portray various emotional states. Usually, generic experiment control software are used, which may present several limitations. In this paper we present a novel approach to the problem, based on a mobile application that can be easily configured by the researcher to set up the desired protocol. This approach not only facilitates and improves study design and data collection, but also provides a plethora of new variables about the participants that, to the best of our knowledge, have never been considered before in this domain, including behavioural research.

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