Abstract
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Abstract
Identifying stress in people is not a trivial or straightforward task, as several factors are involved in detecting the presence or absence of stress. The problem of detect stress has attracted much attention in the last decade and is mainly addressed with physiological signals and in a controlled ambience with specific tasks. However, the widespread use of video cameras permitted the creation of a new non-invasive data collection techniques. The goal of this work is to provide an alternative way to detect stress in the workplace without the need of specific laboratory conditions. For that, a stress detection model based on images analysed with deep learning neural networks was developed. The trained model achieved a F1 = 79.9% on a binary dataset, of stress/non-stress, with an imbalanced ratio of 0.49. This model can be used in a non-invasive application to detect stress and provide recommendations to the collaborators in the workplace in order to help them to control their stress condition. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Abstract
The assertive online strategies of Portuguese luxury fashion brands/designers (LFBDs) are essential for managers to succeed in the digital medium and establish long-lasting relationships with clients. This paper explores the challenges in digitizing all the dis-tinctive elements of a luxury fashion brand: the product characteristics, the luxury atmosphere, the personalization of the service, and the services provided. Fourteen Portuguese brands/designers were selected for content analysis. According to Hansen's framework, 43% of Portuguese LFBDs fail to share information about their com-panies on their websites, and only 43% include promotions. Only 36% have a com-munity outside the websites, compared to 93% of the international luxury fashion brands. Moreover, Portuguese websites lack 360 & DEG; technology and augmented reality. Considering the Digital Visual Merchandising - MVD Grid, Portuguese LFBDs do not allow multiple zooms and 2D F/T cursor change, while international brands feature these tools. Regarding the Social Media Performance Analysis Grid, the global aver-age engagement rate of Portuguese LFBDs on Facebook is 0.19% and on Instagram - 0.89%. According to Social Media Content Analysis Grid, Portuguese brands bet a lot on sharing content in story format, mainly on Instagram; however, Facebook has a higher network value. Therefore, the findings show that Portuguese LFBDs should be present and market their products online. This online presence must be supported by a multi-channel strategy while maintaining luxury product characteristics and elements of differentiation.

Abstract
The main aim of the paper was to estimate the impact of older employees aged 55-74 on productivity compared with other age groups. The research (foundation of the paper) was conducted in 72 countries in the period 2000-2021. Countries were divided into three groups composed of 24 economies according to their GDP pc in 2021, i.e. the lowest GDP pc, the middle GDP pc, and the highest GDP pc countries. The study covered the five age and sex groups of employees: 25-34, 35-44, 45-54, 55-64, and 65-74. The Productive Capacities Index (PCI) built by UNCTAD and its selected categories were assumed to be dependent variables. The research results obtained for three groups of countries indicate that older employees had stronger positive impact on improving PCI than younger employees, especially on human capital development and private sector productivity. Our outcomes also suggest that older employees are better integrated than younger age groups with ICT tools that increase work productivity. To sum up, we can state that older employees can be a key factor in economic development due to their knowledge and experience, provided that others are willing to learn from them and they receive relevant organizational support.

Abstract
Background: Most previous studies assessing multimorbidity in asthma assessed the frequency of individual comorbid diseases. Objective: We aimed to assess the frequency and clinical and economic impact of co-occurring groups of comorbidities (comorbidity patterns using the Charlson Comorbidity Index) on asthma hospitalizations. Methods: We assessed the dataset containing a registration of all Portuguese hospitalizations between 2011-2015. We applied three different approaches (regression models, association rule mining, and decision trees) to assess both the frequency and impact of comorbidities patterns in the length-of-stay, in-hospital mortality and hospital charges. For each approach, separate analyses were performed for episodes with asthma as main and as secondary diagnosis. Separate analyses were performed by participants' age group. Results: We assessed 198340 hospitalizations in patients >18 years old. Both in hospitalizations with asthma as main or secondary diagnosis, combinations of diseases involving cancer, metastasis, cerebrovascular disease, hemiplegia/paraplegia, and liver disease displayed a relevant clinical and economic burden. In hospitalizations having asthma as a secondary diagnosis, we identified several comorbidity patterns involving asthma and associated with increased length-of-stay (average impact of 1.3 [95%CI=0.6-2.0]-3.2 [95%CI=1.8-4.6] additional days), in-hospital mortality (OR range=1.4 [95%CI=1.0-2.0]-7.9 [95%CI=2.6-23.5]) and hospital charges (average additional charges of 351.0 [95%CI=219.1-482.8] to 1470.8 [95%CI=1004.6-1937.0]) Euro compared with hospitalizations without any registered Charlson comorbidity). Consistent results were observed with association rules mining and decision tree approaches. Conclusions: Our findings highlight the importance not only of a complete assessment of patients with asthma, but also of considering the presence of asthma in patients admitted by other diseases, as it may have a relevant impact on clinical and health services outcomes.

Abstract
Oceans all over the world are an important way of sustainability in the lives of many people and have a high impact on the economy of most of the coastal countries. With the growth of underwater activity provided by the development of autonomous and remotely controlled vehicles and with the appearance of new underwater sensors, there is also a need to develop and design more robust underwater wireless networks to provide better and faster communications among the devices connected to the network. Nowadays several technologies provide wireless underwater communications. In this work, we address acoustic technology and the implementation of an acoustic communication system which applies a version of frequency modulation. The main goal of this work is to study the 4-FSK modulation technique and verify the efficiency of the communication system according to variables such as communication distance and baud rate. This implementation uses FPGA systems and Xilinx Vitis Model Composer software and MATLAB Simulink software for simulation. The developed communication system was tested in a controlled environment at two stages: aquarium and pool. The tests were carried out transmitting at 3 different baud rates (40, 100 and 200 kbps) in a distance of 100 cm in the aquarium and 5 meters in the pool.