Abstract
Sponsored advertising on search engines is one of the fastest growing online advertising marketplaces. The space available for paid ads, or positions, is sold using auctions and payment is calculated considering the number of clicks each position receives. Two mechanisms are generally used in position auctions: Generalized Second Price (GSP) (e.g. Google, Yahoo!) and Vickrey-Clarke-Groves (VCG) (e.g. Facebook). To understand which mechanism guarantees the highest payoff to market players (search engines and advertisers), a multi-agent simulation is developed in Netlogo. Using the generated data, a supervised learning-based analysis on search engines and bidders' payoffs is made using linear regression models and regression trees. Results suggest that the average payoff for auctioneers (the search engines) and bidders (the advertisers), the price for each position, and first bidder's payment, are significantly different in the GSP and VCG mechanisms. We also found the mechanism that generates the highest payoff for the search engine is the VCG, while for the bidders it is the GSP.

Abstract
Virtual influencers are rapidly gaining significance in the digital marketing realm. This study offers an overview of the fragmented landscape of virtual influencer research, addressing key contributions, themes, methodologies, and future directions. Employing a bibliometric analysis approach, the research examined 52 articles from the Scopus database, shedding light on the evolving field. Findings underscore a dispersed literature landscape that began in 2020, spanning 44 distinct outlets and involving 138 authors. The prevailing research primarily centers on general social media users' perceptions of virtual influencers, leaving substantial gaps in the study of actual followers. Many pieces of research exhibit a lack of methodological rigor and theoretical framework. As the discipline progresses, there is an emergent need for enhanced methodologies that focus on genuine followers and encompass broader managerial objectives. The prospects for subsequent research in this domain are vast and promising. © 2024, IGI Global. All rights reserved.

Abstract

Abstract
This article compares the effectiveness of the PET/CT scan and bone scintigraphy for the detection of bone metastases in patients with breast cancer. Background Positron emission tomography/computed tomography (PET/CT) has become in recent years a tool for breast cancer (BC) staging. However, its accuracy to detect bone metastases is classically considered inferior to bone scintigraphy (BS). The purpose of this work is to compare the effectiveness of bone metastases detection between PET/CT and BS. Materials and Methods Prospective study of 410 female patients treated in a Comprehensive Cancer Center between 2014 and 2020 that performed PET/CT and BS for staging purposes. The image analysis was performed by 2 senior nuclear medicine physicians. The comparison was performed based on accuracy, sensitivity, and specificity on a patient and anatomical region level and was assessed using McNemar's Test. An average ROC was calculated for the anatomical region analysis. Results PET/CT presented higher values of accuracy and sensitivity (98.0% and 93.83%), surpassing BS (95.61% and 81.48%) in detecting bone disease. There was a significant difference in favor of PET/CT (sensitivity 93.83% vs. 81.48%), however, there is no significant difference in eliminating false positives (specificity 99.09% vs. 99.09%). PET/CT presented the highest accuracy and sensitivity values for most of the bone segments, only surpassed by BS for the cranium. There was a significant difference in favor of PET/CT in the upper limb, spine, thorax (sternum) and lower limb (pelvis and sacrum), and in favor of BS in the cranium. The ROC showed that PET/CT has a higher sensitivity and consistency across the bone segments. Conclusion With the correct imaging protocol, PET/CT does not require BS for patients with BC staging.

Abstract
Virtual reality (VR) technologies have been evolving in recent decades, allowing simulating real-life situations in controlled and safe virtual environments, where they reveal increasingly realistic details. There is an increase in the number of publications on virtual reality interventions in different areas, especially in Education, particularly in interventions with children diagnosed with Autism Spectrum Disorders (ASD). The lack of social skills prevents these children diagnosed with ASD to respond appropriately and adapt to the most diverse daily social situations. On this basis, VR has revealed a set of evidences that present promising results and show great acceptance among the diversified population with ASD. In order to understand how VR may contribute to the improvement of skills, allowing their inclusion, we conducted a systematic review of the literature. We present considerations on the selected studies, identifying the main gaps and pointing out possible directions for future research.

Abstract
The thermal SPA sector is currently experiencing a stable growth trend, which according to the World Tourism Organization (WTO) is expected to continue over the upcoming years. In Portugal, the sector has a very significant profile, with the existence of almost a hundred SPAs and thermal SPAs that generate a business volume (direct and indirect) of over 30 M€ per year. Although the beginning of the process of digital transformation of the sector is already visible, there is no holistic view of the sector which means that the currently existing information systems (IS) do not present a useful response to the needs faced by the sector. Therefore, an architecture proposal was conceived and described for an IS that provides a useful, efficient, and agile response to the needs of the entire thermalism sector and its stakeholders. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.