135 research outputs found

    Projections of Heat Waves Events in the Intra-Americas Region Using Multimodel Ensemble

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    Significant accelerated warming of the Sea Surface Temperature of 0.15°C per decade (1982–2012) was recently detected, which motivated the research for the present consequences and future projections on the heat index and heat waves in the intra-Americas region. Present records every six hours are retrieved from NCEP reanalysis (1948–2015) to calculate heat waves changes. Heat index intensification has been detected in the region since 1998 and driven by surface pressure changes, sinking air enhancement, and warm/weaker cold advection. This regional warmer atmosphere leads to heat waves intensification with changes in both frequency and maximum amplitude distribution. Future projections using a multimodel ensemble mean for five global circulation models were used to project heat waves in the future under two scenarios: RCP4.5 and RCP8.5. Massive heat waves events were projected at the end of the 21st century, particularly in the RCP8.5 scenario. Consequently, the regional climate change in the current time and in the future will require special attention to mitigate the more intense and frequent heat waves impacts on human health, countries’ economies, and energy demands in the IAR

    A hybrid method for the QoS analysis and parameter optimization in time-critical random access wireless sensor networks

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    [EN] Evolution in electronics has led to the development of complex applications in wireless sensor networks (WSNs), where efficient and swift event reporting is needed. In time-critical applications, achieving an adequate report latency is particularly relevant as it allows a proper reaction from the network to the occurring phenomena. It is evident that mean report latency is insufficient as a QoS indicator for time-critical applications. Instead, high percentiles or the whole distribution are much better suited. In certain applications such as target tracking and positioning, the transmission of a certain number of event packets is required to accurately characterize the occurring phenomena. Building on this, we present a hybrid method for obtaining the probability distribution of report latency in random access (RA) WSN protocols. In this method, the distribution of the number of detecting nodes is obtained by simulation, which then allows us to obtain the desired QoS parameters analytically. In this study, we use our method to obtain and optimize the event report latency and energy consumption in RA WSNs. Results show that modifying the transmission parameters during backoff increases the robustness of RA event reporting and also enhances the performance of the WSN in environments where multiple types of events can be detected.This work has been supported by the Ministry of Economy and Competitiveness of Spain through the project TIN2013-47272-C2-1-R, by CONACyT under project Basic Science 183370 and by IPN SIP project 20150584. The research of Israel Leyva-Mayorga is partially funded by grant 383936 CONACYT-Gobierno del Estado de Mexico 2014Leyva-Mayorga, I.; Pla, V.; MartĂ­nez Bauset, J.; Rivero-Angeles, ME. (2017). A hybrid method for the QoS analysis and parameter optimization in time-critical random access wireless sensor networks. Journal of Network and Computer Applications. 83:190-203. https://doi.org/10.1016/j.jnca.2017.01.027S1902038

    MicrografĂ­a cuantitativa y perfiles de HPLC y FTIR de Melissa officinalis y Nepeta cataria (Lamiaceae) de Argentina

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    Melissa officinalis L., so called "Melissa" or "Toronjil", is a perennial aromatic herb, whose leaves are used in traditional medicine as a carminative, digestive and sedative, both in simple as in mixtures. Meanwhile, Nepeta cataria L., commonly called "Cat mint" or "Toronjil", with some similar properties, often replacing M. officinalis in the market, although their chemical composition is not completely matched, and contains an iridoid potentially toxic (nepetalactone). It is therefore necessary to establish diacritic parameters to differentiate these species, both at crude drug level, mixtures and extracts. Samples from various sources in Argentina were studied and documental specimens are preserved in the Herbarium UNSL. Anatomical sections were analyzed, and quantitative micrographic parameters were obtained, together with HPLC and FTIR spectra from methanolic and aqueous lyophilized extracts. Significant differences were detected in the prevailing smell foliage, morphology of leaves and inflorescences, trichomata type, palisade ratio, veinlet termination number, rosmarinic acid concentration (with distinctive HPLC profiles), and the CO/CH relationships obtained by FTIR from the extracts, that together allow adequate differentiation of both drugs, even when they were ground or powdered.Melissa officinalis L., llamada vulgarmente "melisa" o "toronjil", es una hierba perenne, aromática, cuyas hojas son empleadas en medicina popular como carminativo, digestivo y sedante, tanto en droga simple como en asociación. Por su parte Nepeta cataria L., llamada vulgarmente "menta de los gatos" y también "toronjil", con algunas propiedades similares, sustituye con frecuencia a M. officinalis en el mercado, aunque su composición química no es del todo coincidente y contiene un iridoide potencialmente tóxico (nepetalactona). Por ello es necesario establecer parámetros diacríticos para diferenciar ambas especies, a nivel de droga cruda, mezclas y extractos. Fueron estudiados especímenes de diversas procedencias en Argentina, y los ejemplares documentales son conservados en el Herbario UNSL. Se analizaron cortes anatómicos, se registraron los parámetros micrográficos cuantitativos y se obtuvieron espectros de HPLC y FTIR a partir de extractos metanólicos y acuosos liofilizados. Fueron detectadas diferencias significativas entre ambas especies en cuanto al aroma prevaleciente del follaje, la exomorfología de hojas e inflorescencias, los tipos tricomáticos, la relación de empalizada, el número de terminales de nerviación, la concentración de ácido rosmarínico (con perfiles HPLC distintivos), y las relaciones CO/CH obtenidas por FTIR a partir de los extractos, caracteres que en conjunto permiten una diferenciación adecuada de ambas drogas, aún cuando se presenten molidas o reducidas a polvo.Fil: Petenatti, Marta E.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Gette, Maria de Los Angeles. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Camí, Gerardo Enrique. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Popovich, Mariana C.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Marchevsky, Eduardo Jorge. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: del Vitto, Luis Angel. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Petenatti, Elisa Margarita. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentin

    QoSatAr: a cross-layer architecture for E2E QoS provisioning over DVB-S2 broadband satellite systems

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    This article presents QoSatAr, a cross-layer architecture developed to provide end-to-end quality of service (QoS) guarantees for Internet protocol (IP) traffic over the Digital Video Broadcasting-Second generation (DVB-S2) satellite systems. The architecture design is based on a cross-layer optimization between the physical layer and the network layer to provide QoS provisioning based on the bandwidth availability present in the DVB-S2 satellite channel. Our design is developed at the satellite-independent layers, being in compliance with the ETSI-BSM-QoS standards. The architecture is set up inside the gateway, it includes a Re-Queuing Mechanism (RQM) to enhance the goodput of the EF and AF traffic classes and an adaptive IP scheduler to guarantee the high-priority traffic classes taking into account the channel conditions affected by rain events. One of the most important aspect of the architecture design is that QoSatAr is able to guarantee the QoS requirements for specific traffic flows considering a single parameter: the bandwidth availability which is set at the physical layer (considering adaptive code and modulation adaptation) and sent to the network layer by means of a cross-layer optimization. The architecture has been evaluated using the NS-2 simulator. In this article, we present evaluation metrics, extensive simulations results and conclusions about the performance of the proposed QoSatAr when it is evaluated over a DVB-S2 satellite scenario. The key results show that the implementation of this architecture enables to keep control of the satellite system load while guaranteeing the QoS levels for the high-priority traffic classes even when bandwidth variations due to rain events are experienced. Moreover, using the RQM mechanism the user’s quality of experience is improved while keeping lower delay and jitter values for the high-priority traffic classes. In particular, the AF goodput is enhanced around 33% over the drop tail scheme (on average)

    The Ship of Theseus Puzzle

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    Does the Ship of Theseus present a genuine puzzle about persistence due to conflicting intuitions based on “continuity of form” and “continuity of matter” pulling in opposite directions? Philosophers are divided. Some claim that it presents a genuine puzzle but disagree over whether there is a solution. Others claim that there is no puzzle at all since the case has an obvious solution. To assess these proposals, we conducted a cross-cultural study involving nearly 3,000 people across twenty-two countries, speaking eighteen different languages. Our results speak against the proposal that there is no puzzle at all and against the proposal that there is a puzzle but one that has no solution. Our results suggest that there are two criteria—“continuity of form” and “continuity of matter”— that constitute our concept of persistence and these two criteria receive different weightings in settling matters concerning persistence
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