Proximity Sensor for Measuring Social Interaction in a School Environment.

Social interactions are characterized by being very diverse and changing over time. Understanding this diversity and dynamics, as well as their emerging patterns, is of great interest from social, health, and educational perspectives. The development of new devices has been made possible in recent years by advances in applied technology. This paper presents the design and development of a novel device composed of several sensors. Specifically, we propose a proximity sensor integrated by three devices: a Bluetooth sensor, a global positioning system (GPS) unit and an accelerometer. By means of this sensor it is possible to detect the presence of neighboring sensors in various configurations and operating conditions. Profiles based on the Received Signal Strength Indicator (RSSI) exhibit behavior consistent with that reported by empirical relationships. The present sensor is functional in detecting the proximity of other sensors and is thus useful for the identification of interactions between people in relevant contexts such as schools.

Indoor environment dataset based on RSSI collected with bluetooth devices.

This paper describes a data collection experiment focused on researching indoor positioning systems using Bluetooth Low Energy (BLE) devices. The study was conducted in a real-world scenario with 150 test points and collected signals from 11 mobile devices. The dataset contains RSSI values from the mobile devices in relation to 15 fixed anchor nodes in the experimentation scenario. The dataset includes data on device identification, labels and coordinates of test points, and the room where the data was collected. The data is organized as CSV files and offers valuable information for researchers developing and assessing location models. By sharing this dataset, we aim to support the creation of robust and precise indoor localization models.

Inmunoensayo quimioluminiscente para sífilis en donantes de sangre: ¿Los valores de lectura se correlacionan con el estado de la infección? / Chemiluminescent immunoassay for syphilis in blood donors: do signal strength values correlate with the infection status? / Imunoensaio quimioluminescente para sífilis em doadores de sangue: os valores de leitura estão correlacionados com o estado da infecção?

Resumen El objetivo del trabajo fue comparar el desempeño del tamizaje treponémico y no treponémico en dos períodos próximos en el tiempo en donantes de sangre y analizar la asociación de la intensidad de la señal de la prueba quimioluminiscente (QL) con la reactividad del enzimoinmunoanálisis (ELISA) y la reagina plasmática rápida (RPR). Se realizó el tamizaje con pruebas treponémicas. Se analizó la distribución de los valores de señal/valor de corte (S/CO) obtenidos por QL en función del ELISA y RPR y se evaluó su asociación entre dos grupos de resultados de laboratorio (1) ELISA+/RPR+ y (2): ELISA+/RPR-. Se procesaron 76 794 donaciones voluntarias. Al comparar las medianas entre grupos, se encontró que la relación S/CO de QL fue significativamente mayor para los donantes del Grupo 1 (19,5 vs. 8,10; p<0,001). Se concluye que la intensidad de la señal de la prueba cualitativa QL estaría asociada con la reactividad de la RPR y guardaría relación con el curso de la infección.

Abstract The objective of this work was to compare the performance of treponemal and non-treponemal screening in two periods close in time in blood donors and to analyse the association of the signal strength (signal-to-cutoff, S/ CO) of the chemiluminescent immunoassay (CIA) with the reactivity of the enzymeimmunoassay (EIA) and the rapid plasma reagin (RPR). Donors were screened with treponemal tests. The distribution of the S/CO values obtained by CIA was analysed based on EIA and RPR, and its association was evaluated. Group 1: ELISA+/RPR+ donors and Group 2: ELISA+/RPR-. A total of 76,794 voluntary donations were processed. Comparing the means between groups, it was found that the CIA S/CO ratio was significantly higher for Group 1 donors (19.5 vs. 8.10; p<0.001). In conclusion, the signal strength of the qualitative CIA test would be associated with the reactivity of the RPR and would be related to the course of the infection.

Resumo O objetivo do trabalho foi comparar o desempenho da triagem treponêmica e não treponêmica em dois períodos próximos no tempo em doadores de sangue e analisar a associação da intensidade do sinal da prova quimioluminescente (QL) com a reatividade da análise imunoenzimática (ELISA) e a reagina plasmática rápida (RPR). Foi realizada uma triagem com provas treponêmicas. Foi analisada a distribuição dos valores de sinal/valor de corte (S/CO) obtidos por QL em função da ELISA e RPR, e também a associação entre dois grupos de resultados laboratoriais (1): ELISA+/RPR+ e (2) ELISA+/ RPR-). Foram procesadas 76 794 doações de sangue voluntárias. Ao comparar as medianas entre os grupos, obteve-se que a relação S/CO de QL foi significativamente maior para os doadores de sangue do grupo 1 (19,5 vs. 8,10; p<0,001). Em conclusão, a intensidade do sinal da prova qualitativa QL estaria associada com a reatividade da RPR e guardaria relação com o curso da infecção.

A Novel and Adaptive Angle Diversity-Based Receiver for 6G Underground Mining VLC Systems.

Visible light communication (VLC) is considered an enabling technology for future 6G wireless systems. Among the many applications in which VLC systems are used, one of them is harsh environments such as Underground Mining (UM) tunnels. However, these environments are subject to degrading environmental and intrinsic challenges for optical links. Therefore, current research should focus on solutions to mitigate these problems and improve the performance of Underground Mining Visible Light Communication (UM-VLC) systems. In this context, this article presents a novel solution that involves an improvement to the Angle Diversity Receivers (ADRs) based on the adaptive orientation of the Photo-Diodes (PDs) in terms of the Received Signal Strength Ratio (RSSR) scheme. Specifically, this methodology is implemented in a hemidodecahedral ADR and evaluated in a simulated UM-VLC scenario. The performance of the proposed design is evaluated using metrics such as received power, user data rate, and bit error rate (BER). Furthermore, our approach is compared with state-of-the-art ADRs implemented with fixed PDs and with the Time of Arrival (ToA) reception method. An improvement of at least 60% in terms of the analyzed metrics compared to state-of-the-art solutions is obtained. Therefore, the numerical results demonstrate that the hemidodecahedral ADR, with adaptive orientation PDs, enhances the received optical signal. Furthermore, the proposed scheme improves the performance of the UM-VLC system due to its optimum adaptive angular positioning, which is completed according to the strongest optical received signal power. By improving the performance of the UM-VLC system, this novel method contributes to further consideration of VLC systems as potential and enabling technologies for future 6G deployments.

Improving Signal-Strength Aggregation for Mobile Crowdsourcing Scenarios.

Due to its huge impact on the overall quality of service (QoS) of wireless networks, both academic and industrial research have actively focused on analyzing the received signal strength in areas of particular interest. In this paper, we propose the improvement of signal-strength aggregation with a special focus on Mobile Crowdsourcing scenarios by avoiding common issues related to the mishandling of log-scaled signal values, and by the proposal of a novel aggregation method based on interpolation. Our paper presents two clear contributions. First, we discuss the misuse of log-scaled signal-strength values, which is a persistent problem within the mobile computing community. We present the physical and mathematical formalities on how signal-strength values must be handled in a scientific environment. Second, we present a solution to the difficulties of aggregating signal strength in Mobile Crowdsourcing scenarios, as a low number of measurements and nonuniformity in spatial distribution. Our proposed method obtained consistently lower Root Mean Squared Error (RMSE) values than other commonly used methods at estimating the expected value of signal strength over an area. Both contributions of this paper are important for several recent pieces of research that characterize signal strength for an area of interest.

Revisiting Gaussian Process Regression Modeling for Localization in Wireless Sensor Networks.

Signal strength-based positioning in wireless sensor networks is a key technology for seamless, ubiquitous localization, especially in areas where Global Navigation Satellite System (GNSS) signals propagate poorly. To enable wireless local area network (WLAN) location fingerprinting in larger areas while maintaining accuracy, methods to reduce the effort of radio map creation must be consolidated and automatized. Gaussian process regression has been applied to overcome this issue, also with auspicious results, but the fit of the model was never thoroughly assessed. Instead, most studies trained a readily available model, relying on the zero mean and squared exponential covariance function, without further scrutinization. This paper studies the Gaussian process regression model selection for WLAN fingerprinting in indoor and outdoor environments. We train several models for indoor/outdoor- and combined areas; we evaluate them quantitatively and compare them by means of adequate model measures, hence assessing the fit of these models directly. To illuminate the quality of the model fit, the residuals of the proposed model are investigated, as well. Comparative experiments on the positioning performance verify and conclude the model selection. In this way, we show that the standard model is not the most appropriate, discuss alternatives and present our best candidate.