Examinando por Autor "Torres, R."
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Ítem A middleware for creating physical mashups of things(CEUR-WS, 2017) Herrera, H.; Torres, R.Nowadays, “things” deployed in cities are crucial to gather data to support decision making systems. Unfortunately, there is a low level of reuse of “things” between smart city applications of different organizations because “things” were unknown to developers or because it was harder to reuse them than use new ones due to technical details. In this ongoing work, we propose to convert “things” into active entities capable of discovering and organizing themselves driven by the applications goals’ satisfaction. Moreover, “things” are capable of collaborating between them in order to satisfy or maintain satisfied the published goals of applications. To validate the feasibility of our proposal, we are building mashThings, an Internet of Things (IoT) platform to build smart city applications as physical mashups, where the middleware layer is augmented by a multiagent layer of broker agents representing the available “things” in the city.Ítem An Efficient Multi-Level Convolutional Neural Network Approach for White Blood Cells Classification(MDPI, 2022-02) Cheuque, C.; Querales, M.; León, R.; Salas, R.; Torres, R.The evaluation of white blood cells is essential to assess the quality of the human immune system; however, the assessment of the blood smear depends on the pathologist’s expertise. Most machine learning tools make a one-level classification for white blood cell classification. This work presents a two-stage hybrid multi-level scheme that efficiently classifies four cell groups: lymphocytes and monocytes (mononuclear) and segmented neutrophils and eosinophils (polymorphonuclear). At the first level, a Faster R-CNN network is applied for the identification of the region of interest of white blood cells, together with the separation of mononuclear cells from polymorphonuclear cells. Once separated, two parallel convolutional neural networks with the MobileNet structure are used to recognize the subclasses in the second level. The results obtained using Monte Carlo cross-validation show that the proposed model has a performance metric of around 98.4% (accuracy, recall, precision, and F1-score). The proposed model represents a good alternative for computer-aided diagnosis (CAD) tools for supporting the pathologist in the clinical laboratory in assessing white blood cells from blood smear images.Ítem Characterization of the Chilean Public Procurement Ecosystem Using Social Network Analysis(Institute of Electrical and Electronics Engineers Inc., 2020) Leiva, F.; Torres, R.; Nicolis, o.; Fe, R.'Mercado Público' is a Chilean electronic platform used for purchasing processes by Chilean public organizations for the last two decades. The main aim of this study is to characterize the Chilean public procurement ecosystem by using social network analysis to detect the main communities of suppliers based on who awarded the tenders. To do this, we use a methodology that first represents the bidder-supplier relationship as a bipartite graph using purchase order information. Then we project the bipartite graph onto a monopartite graph of suppliers. We end by detecting the main supplier communities using a modularity algorithm. When we applied this methodology to the large tender segment in the Chilean public procurement market over a period of four years, we successfully detected the five largest communities and the micro and small companies which had the greatest rate of participation over time.Ítem Human peritoneal mesothelial cell death induced by high-glucose hypertonic solution involves Ca2+ and Na+ ions and oxidative stress with the participation of PKC/NOX2 and PI3K/Akt pathways(Frontiers Media, 2017-06) Simon, F.; Tapia, P.; Armisen, R.; Echeverria, C.; Gatica, S.; Vallejos, A.; Pacheco, A.; Sanhueza, M.E.; Alvo, M.; Segovia, E.; Torres, R.Chronic peritoneal dialysis (PD) therapy is equally efficient as hemodialysis while providing greater patient comfort and mobility. Therefore, PD is the treatment of choice for several types of renal patients. During PD, a high-glucose hyperosmotic (HGH) solution is administered into the peritoneal cavity to generate an osmotic gradient that promotes water and solutes transport from peritoneal blood to the dialysis solution. Unfortunately, PD has been associated with a loss of peritoneal viability and function through the generation of a severe inflammatory state that induces human peritoneal mesothelial cell (HPMC) death. Despite this deleterious effect, the precise molecular mechanism of HPMC death as induced by HGH solutions is far from being understood. Therefore, the aim of this study was to explore the pathways involved in HGH solution-induced HPMC death. HGH-induced HPMC death included influxes of intracellular Ca2+ and Na+. Furthermore, HGH-induced HPMC death was inhibited by antioxidant and reducing agents. In line with this, HPMC death was induced solely by increased oxidative stress. In addition to this, the cPKC/NOX2 and PI3K/Akt intracellular signaling pathways also participated in HGH-induced HPMC death. The participation of PI3K/Akt intracellular is in agreement with previously shown in rat PMC apoptosis. These findings contribute toward fully elucidating the underlying molecular mechanism mediating peritoneal mesothelial cell death induced by high-glucose solutions during peritoneal dialysis.Ítem Implementing a signing forms mechanism in an open XMPP Server to reduce successful network attacks(CEUR-WS, 2018-10) Aros, M.; Torres, R.Servers implementing the eXtensible Messag-ing and Presence Protocol (XMPP) enable the near-real-time exchange of structured yet extensible data between any two or more network entities. In this paper we propose to address network attacks, a security issue, by implementing signing forms over an in-band registration mechanism. We validate our proposal implementing this mechanism over OpenFire, which is a free, community-supported and open source XMPP server. Our experiments showed that the number of successful attacks was reduced to 0 when our proposal is implemented. © 2018 CEUR-WS. All rights reserved.Ítem Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)(Public Library of Science, 2013-07) Manríquez, P.; Jara, M.; Mardone, M.; Navarro, J.; Torres, R.; Lardies, M.; Vargas, C.; Duarte, C.; Widdicombe, S.; Salisbury, J.; Lagos, N.Background:Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation.Methodology/Principal Findings:The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 μatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 μatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab.Conclusions and Significance:These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.