Browsing by Author "Oliveira, Rui"
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- Exploring the use of control packets in LoRa medium access: a scalability analysisPublication . Fernandes, Rui; Oliveira, Rui; Luís, Miguel; Sargento, SusanaLoRa technology has been attesting itself as one of the most prominent and widely adopted low power wide area technologies. Highly compatible with Internet of Things (IoT) applications and urban environments, this technology enables large range communications although with small bandwidths and duty cycle restrictions. In this work, we propose a distinct way of dealing with the Medium Access Control (MAC) in LoRa, through the use of control packets to enhance the technology performance in urban city scenarios, where a large number of nodes is expected. The proposed protocol is asynchronous and takes into account the energy expenditure. We compare this scheme with the standard (LoRaWAN) by considering different network densities and packet sizes, and through different LoRa collision models. Performance results, such as network throughput and fairness index, show that, depending on the ratio between data and control packet lengths, it is possible to greatly improve the bit rate and overall network performance, even if increasing the duty-cycle restriction time due to the addition of overhead.
- LoRa connectivity analysis for urban coverage in real mobile environmentsPublication . Oliveira, Rui; Luís, Miguel; Sargento, SusanaFor the last few years, LoRa technology has been affirming itself as one of the most prominent and widely adopted low power wide area technologies. Very compatible with Internet of Things (IoT) applications and urban environments, this technology is capable of long range communications although with small bandwidths, and consequently, low data rates. Nevertheless, the quality of LoRa communications, like many other wireless technologies, are highly dependent on the transmission's context. In this work, we evaluate the performance of LoRa communications in a mobile sensing scenario, and study its capability to give wireless coverage to a small-size city. Experimental results show that velocity has a consistent and increasing impact on the packet delivery ratio, and that the coverage capability is much more dependent on the terrain distribution and Line-of-Sight (LoS), than on the distance between the mobile node and the gateway.
- Measuring DNA modifications with the comet assay: a compendium of protocolsPublication . Collins, Andrew; Møller, Peter; Gajski, Goran; Vodenková, Soňa; Abdulwahed, Abdulhadi; Anderson, Diana; Bankoglu, Ezgi Eyluel; Bonassi, Stefano; Boutet-Robinet, Elisa; Brunborg, Gunnar; Chao, Christy; Cooke, Marcus S.; Costa, Carla; Costa, Solange; Dhawan, Alok; de Lapuente, Joaquin; Bo’, Cristian Del; Dubus, Julien; Dusinska, Maria; Duthie, Susan J.; Yamani, Naouale El; Engelward, Bevin; Gaivão, Isabel; Giovannelli, Lisa; Godschalk, Roger; Guilherme, Sofia; Gutzkow, Kristine B.; Habas, Khaled; Hernández, Alba; Herrero, Oscar; Isidori, Marina; Jha, Awadhesh N.; Knasmüller, Siegfried; Kooter, Ingeborg M.; Koppen, Gudrun; Kruszewski, Marcin; Ladeira, Carina; Laffon, Blanca; Larramendy, Marcelo; Hégarat, Ludovic Le; Lewies, Angélique; Lewinska, Anna; Liwszyc, Guillermo E.; de Cerain, Adela López; Manjanatha, Mugimane; Marcos, Ricard; Milić, Mirta; de Andrade, Vanessa Moraes; Moretti, Massimo; Muruzabal, Damian; Novak, Matjaž; Oliveira, Rui; Olsen, Ann-Karin; Owiti, Norah; Pacheco, Mário; Pandey, Alok K.; Pfuhler, Stefan; Pourrut, Bertrand; Reisinger, Kerstin; Rojas, Emilio; Rundén-Pran, Elise; Sanz-Serrano, Julen; Shaposhnikov, Sergey; Sipinen, Ville; Smeets, Karen; Stopper, Helga; Teixeira, João Paulo; Valdiglesias, Vanessa; Valverde, Mahara; van Acker, Frederique; van Schooten, Frederik-Jan; Vasquez, Marie; Wentzel, Johannes F.; Wnuk, Maciej; Wouters, Annelies; Žegura, Bojana; Zikmund, Tomas; Langie, Sabine A. S.; Azqueta, AmayaThe comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to humans. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers, some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry, and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species, and types of DNA damage, thereby demonstrating its versatility.
- The Arraiolos – Portugal – Moderate-Sized 2018 (M = 4.9) earthquake of January 15 and aftershocks: preliminary resultsPublication . Borges, José; Caldeira, Bento; Fontiela, João; Custódio, Susana; Dias, Nuno; Waschilala, Piedade; Oliveira, Rui; Vales, Dina; Bezzeghoud, Mourad; Araújo, Alexandre; Carrilho, Fernando; Corela, Carlos; Rio, Inês; Vaz, José; Matias, LuísOn 15 January 2018 at 11:51 UTC, an earthquake of 4.9 ML occurred in the Northeast of Arraiolos region near Aldeia da Serra village. The hypocentral location, determined by Instituto Português do Mar e da Atmosfera (IPMA), has coordinates 38.79 N, 7.93 W at 11 km depth. The focal mechanisms determined by P-wave first motion polarities and waveforms inversion indicate a dominance of strike-slip events with nodal plans near NS (left lateral) and EW (right lateral) directions. Due to the lower magnitude, the earthquake didn’t cause damage but was widely felt in the Centre and South of Portugal mainland. In the vicinity of the epicentre, at the Aldeia da Serra village, it reached a maximum intensity VI, having been felt with intensity IV/V in the city of Évora, about 20 km from the epicentre. The event was also felt with intensity III in Lisbon at more than 100 km from the epicentre. This event caused alarm in the population that haven’t felt an earthquake for several decades. It also raised the media attention with many reports and interviews on TV and newspapers. The main ear thquake was immediatel y followed by a sequence of aftershocks of which the largest one, with ML=3.1, occurred the 1st February, fifteen days after the main shock and was largely felt by the population in the region of Arraiolos.