Capacity Analysis of IEEE 802.11ah WLANs for M2M Communications

Focusing on the increasing market of the sensors and actuators networks, the IEEE 802.11ah Task Group is currently working on the standardization of a new amendment. This new amendment will operate at the sub-1GHz band, ensure transmission ranges up to 1 Km, data rates above 100 kbps and very low power operation. With IEEE 802.11ah, the WLANs will offer a solution for applications such as smart metering, plan automation, eHealth or surveillance. Moreover, thanks to a hierarchical signalling, the IEEE 802.11ah will be able to manage a higher number of stations (STAs) and improve the 802.11 Power Saving Mechanisms. In order to support a high number of STAs, two different signalling modes are proposed, TIM and Non-TIM Offset. In this paper we present a theoretical model to predict the maximum number of STAs supported by both modes depending on the traffic load and the data rate used. Moreover, the IEEE 802.11ah performance and energy consumption for both signalling modes and for different traffic patterns and data rates is evaluated. Results show that both modes achieve similar Packet Delivery Ratio values but the energy consumed with the TIM Offset is, in average, a 11.7% lower.Comment: Multiple Access Communications 201

Desenvolupament d'un sistema per a la fabricació de prototips dús mèdic mitjançant tecnologies d'impressió 3D amb liquids solidificables

Les tecnologies d’impressió 3D fins al moment s’han centrat en el desenvolupament i millora de les impressions amb materials termoplàstics basats en l’extrusió de filament rígid que donen lloc a productes igualment rígids. En els últims anys però, l’interès del consumidor en la obtenció de productes de baixes dureses no assolibles pels mecanismes de producció amb filaments termoplàstics han anat en augment. Aquesta nova necessitat ha suposat un repte als fabricants i desenvolupadors de tecnologies d’impressió que s’han vist obligats a investigar en disseny i la producció de sistemes mitjançant líquids solidificables per poder satisfer les noves demandes del mercat. La majoria de solucions presentades per les grans empreses del sector fins al moment impliquen l’ús d’impressores especialitzades d’alta complexitat amb un cost molt elevat. En aquest treball s’ha volgut donar una solució a aquesta demanda mitjançant l’ús de líquids solidificables però basat en l’ús una impressora de filament termoplàstic convencional, tenint com a objectiu la producció de prototips mèdics per a assajos clínics. Els resultats obtinguts esperen donar sortida a una nova metodologia prometedora que faci assequible la impressió de materials tous donant lloc a productes que requereixen una alta qualitat com és el cas de prototips mèdics

Molecular and thermodynamic properties of zwitterions versus ionic liquids: A comprehensive computational analysis to develop advanced separation processes

WILEY: "This is the peer reviewed version of the following article: ChemPhysChem 19.7 (2018): 801-815, which has been published in final form at http://doi.org/10.1002/cphc.201701093. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions." Este artículo apareció anteriormente con el siguiente título "Exploring molecular and thermodynamic properties of zwitterions vs ionic liquids: A comprehensive computational analysis to develop advanced separation processes"Zwitterion ionic liquids (ZIs) are compounds in which both counterions are covalently tethered, conferring them with unique characteristics; however, most of their properties are still unknown, representing a bottleneck to exploit their practical applications. Herein, the molecular and fluid properties of ZIs and their mixtures were explored by means of quantum chemical analysis based on the density functional theory (DFT) and COSMO-RS method, and compared against homologous ionic liquids (ILs) to provide a comprehensive overview of the effect of the distinct structures on their physicochemical and thermodynamic behavior. Overall, ZIs were revealed as compounds with higher polarity and stronger hydrogen-bonding capacity, implying higher density, viscosity, melting point, and even lower volatility than structurally similar ILs. The phase equilibrium of binary and ternary systems supports stronger attractive interactions between ZIs and polar compounds, whereas higher liquid–liquid immiscibility with nonpolar compounds may be expected. Ultimately, the performance of ZIs in the wider context of separation processes is illustrated, while providing molecular insights to allow their selection and design for relevant applicationsThe authors would like to acknowledge to Comunidad Autónoma de Madrid for the Project S2013/MAE-2800 and to Ministerio de Economía y Competitividad (MINECO) of Spain for financial support of Projects CTQ2014-52288-R. We are very grateful to Centro de Computación Científica de la Universidad Autónoma de Madrid for computational facilities. We all would like to acknowledge kind support in the framework of the COST Action EXIL-Exchange on Ionic Liquids (CM1206)

Novel E3 Ubiquitin Ligases That Regulate Histone Protein Levels in the Budding Yeast Saccharomyces cerevisiae

Core histone proteins are essential for packaging the genomic DNA into chromatin in all eukaryotes. Since multiple genes encode these histone proteins, there is potential for generating more histones than what is required for chromatin assembly. The positively charged histones have a very high affinity for negatively charged molecules such as DNA, and any excess of histone proteins results in deleterious effects on genomic stability and cell viability. Hence, histone levels are known to be tightly regulated via transcriptional, posttranscriptional and posttranslational mechanisms. We have previously elucidated the posttranslational regulation of histone protein levels by the ubiquitin-proteasome pathway involving the E2 ubiquitin conjugating enzymes Ubc4/5 and the HECT (Homologous to E6-AP C-Terminus) domain containing E3 ligase Tom1 in the budding yeast. Here we report the identification of four additional E3 ligases containing the RING (Really Interesting New Gene) finger domains that are involved in the ubiquitylation and subsequent degradation of excess histones in yeast. These E3 ligases are Pep5, Snt2 as well as two previously uncharacterized Open Reading Frames (ORFs) YKR017C and YDR266C that we have named Hel1 and Hel2 (for Histone E3 Ligases) respectively. Mutants lacking these E3 ligases are sensitive to histone overexpression as they fail to degrade excess histones and accumulate high levels of endogenous histones on histone chaperones. Co-immunoprecipitation assays showed that these E3 ligases interact with the major E2 enzyme Ubc4 that is involved in the degradation related ubiquitylation of histones. Using mutagenesis we further demonstrate that the RING domains of Hel1, Hel2 and Snt2 are required for histone regulation. Lastly, mutants corresponding to Hel1, Hel2 and Pep5 are sensitive to replication inhibitors. Overall, our results highlight the importance of posttranslational histone regulatory mechanisms that employ multiple E3 ubiquitin ligases to ensure excess histone degradation and thus contribute to the maintenance of genomic stability

BiGlobal and point vortex methods for the instability analysis of wakes

To better understand destruction mechanisms of wake-vortices behind aircraft, the point vortex method for stability (inviscid) used by Crow is here compared with viscous modal global stability analysis of the linearized Navier-Stokes equations acting on a two-dimensional basic flow, i.e. BiGlobal stability analysis. The fact that the BiGlobal method is viscous, and uses a flnite área vortex model, gives rise to results somewhat different from the point vortex model. It adds more parameters to the problem, but is more realistic

E3MS: A traffic engineering prototype for autoprovisioning services in IP/DiffServ/MPLS networks

This paper presents the testbed definition, implementation and trials of a new strategy for traffic autoprovisioning for MPLS and IP/DiffServ. This is the proof of concept of a new scenario for traffic engineering, for selfconfiguring control and end-to-end quality of service management by means of a tool based on Web Services. The system is structured in 3 layers: A Graphical User Interface, a Network Elements layer (an interface to physical devices) and, in the middle, a Network Management System layer, where decisions about admission, load balancing, path selection, rerouting and bandwidth allocation per class are taken. The system includes Dynamic Resource Allocation (DRA) and Background Monitoring System (BMS) modules to globally manage network resources. The so-called Squatter and Legalization mechanisms are introduced as novelties added to traffic engineering. Those strategies permit the use of part of the available resources from other classes only while unused by the class owning them. The trials hav validated the management system, using Cisco routers.Postprint (published version

Effect of the non-stationarity of rainfall events on the design of hydraulic structures for runoff management and its applications to a case study at Gordo Creek watershed in Cartagena de Indias, Colombia

The 24-h maximum rainfall (P 24h-max ) observations recorded at the synoptic weather station of Rafael Núñez airport (Cartagena de Indias, Colombia) were analyzed, and a linear increasing trend over time was identified. It was also noticed that the occurrence of the rainfall value (over the years of record) for a return period of 10 years under stationary conditions (148.1 mm) increased, which evidences a change in rainfall patterns. In these cases, the typical stationary frequency analysis is unable to capture such a change. So, in order to further evaluate rainfall observations, frequency analyses of P 24h-max for stationary and non-stationary conditions were carried out (by using the generalized extreme value distribution). The goodness-of-fit test of Akaike Information Criterion (AIC), with values of 753.3721 and 747.5103 for stationary and non-stationary conditions respectively, showed that the latter best depicts the increasing rainfall pattern. Values of rainfall were later estimated for different return periods (2, 5, 10, 25, 50, and 100 years) to quantify the increase (non-stationary versus stationary condition), which ranged 6% to 12% for return periods from 5 years to 100 years, and 44% for a 2-year return period. The effect of these findings were tested in the Gordo creek watershed by first calculating the resulting direct surface runoff (DSR) for various return periods, and then modeling the hydraulic behavior of the downstream area (composed of a 178.5-m creek's reach and an existing box-culvert located at the watershed outlet) that undergoes flooding events every year. The resulting DSR increase oscillated between 8% and 19% for return periods from 5 to 100 years, and 77% for a 2-year return period when the non-stationary and stationary scenarios were compared. The results of this study shed light upon to the precautions that designers should take when selecting a design, based upon rainfall observed, as it may result in an underestimation of both the direct surface runoff and the size of the hydraulic structures for runoff and flood management throughout the city. © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license

Validación en español de las propiedades psicométricas de la Generic Multifaceted Automaticity Scale (GMAS) para actividades físicas

Esta investigación presenta la validación al español de la Generic Multifaceted Automaticity Scale (GMAS) elaborada y validada en francés por Boiché et al. (2016). Esta escala mide tres propiedades de la automaticidad aplicadas a las actividades físicas: (a) la falta de intencionalidad para activar un comportamiento; (b) la eficiencia en su ejecución; y (c) la dificultad para controlarlo una vez adoptado. Dos estudios evaluaron sus propiedades psicométricas. En el primer estudio (N= 245) se realizaron un análisis factorial, una estimación de la coherencia interna a través del alpha de Cronbach y de validez convergente. Se confirmó un modelo en tres factores: (a) falta de intencionalidad, (b) la eficiencia y (c) el control (χ²/df = 2,24; TLI = .96; CFI = .97; SRMR=.08 RMSEA = .08; 90 [.05 - .10]). La GMAS presentó una consistencia interna satisfactoria (α =.89). Asimismo, los resultados mostraron que cuanto mayor sea la automaticidad, mayores serán los niveles de actividad física. Un segundo estudio (N=151) mostró que la automaticidad predijo significativamente la adopción de los transportes activos (β =.29; p < .05) independientemente de las intenciones. La GMAS es un instrumento válido en español para evaluar las propiedades automáticas de las actividades físicas.This research presents the Spanish validation of the Generic Multifaceted Automaticity Scale (GMAS) developed and validated in French by Boiché et al. (2016). This scale measures three properties of automaticity applied to physical activities: (a) the intentionality to activate a behaviour; (b) the efficiency of its execution; and (c) the difficulty to control it once adopted. Two studies evaluated its psychometric properties. Two studies evaluate the GMAS psychometric properties. In the first study (N= 245), a factorial analysis, reliability estimation by Cronbach's alpha, and convergent validity analysis were performed. A three-factor model was confirmed: (a) lack of intentionality, (b) efficiency and (c) control (χ²/df = 2,24; TLI = .96; CFI = .97; SRMR=.08 RMSEA = .08; 90 [.05 - .10]) with a good internal consistency (α =.89). The results show that high levels of automaticity are related to high levels of physical activity. The second study (N=151) shows that automaticity predicts the adoption of active modes of transportation, over and beyond intentions (β = .29; p < .05). These results suggest that the Spanish version of the GMAS is a valid instrument to evaluate the automatic properties of physical activity behaviours.Esta estudo apresenta a validação em espanhol da Generic Multifaceted Automaticity Scale (GMAS) elaborada e validada em francês por Boiché et al. (2016). Esta escala mede três propriedades de automaticidade aplicadas às atividades físicas: (a) a intencionalidade de ativar um comportamento; (b) a eficiência de sua execução; e (c) a dificuldade de controlá-lo uma vez adotado. Dois estudos avaliaram as propriedades psicométricas do GMAS. No primeiro estudo (N = 245) foi realizado análise fatorial, estimação de fiabilidade pelo alpha de Cronbach e validação de convergência. Um modelo de três fatores foi confirmado: a) falta de intencionalidade, b) eficiência e c) controlo (χ²/df = 2,24; TLI = .96; CFI = .97; SRMR=.08 RMSEA = .08; 90 [.05 - .10]) e uma boa consistência interna (α =.89). Conjuntamente, altos níveis de automaticidade foram correlacionados com altos níveis de atividade física. O segundo estudo (N = 151) revelou que a automaticidade previu a adoção de modos ativos de transporte, para além das intenções (β =.29; p < .05). A versão em espanhol do GMAS é um instrumento válido para avaliar as propriedades automáticas dos comportamentos relacionados a atividade física

Simulating whole supercomputer applications

Architecture simulation tools are extremely useful not only to predict the performance of future system designs, but also to analyze and improve the performance of software running on well know architectures. However, since power and complexity issues stopped the progress of single-thread performance, simulation speed no longer scales with technology: systems get larger and faster, but simulators do not get any faster. Detailed simulation of full-scale applications running on large clusters with hundreds or thousands of processors is not feasible. In this paper we present a methodology that allows detailed simulation of large-scale MPI applications running on systems with thousands of processors with low resource cost. Our methodology allows detailed processor simulation, from the memory and cache hierarchy down to the functional units and the pipeline structure. This feature enables software performance analysis beyond what performance counters would allow. In addition, it enables performance prediction targeting non-existent architectures and systems, that is, systems for which no performance data can be used as a reference. For example, detailed analysis of the weather forecasting application WRF reveals that it is highly optimized for cache locality, and is strongly compute bound, with faster functional units having the greatest impact on its performance. Also, analysis of next-generation CMP clusters show that performance may start to decline beyond 8 processors per chip due to shared resource contention, regardless of the benefits of through-memory communication.Postprint (published version

Seasonal temperature trends on the Spanish mainland: a secular study (1916-2015)

Trends in seasonal mean values of maximum and minimum temperature are analysed in the Spanish mainland from the new MOTEDAS_century database. This new data set has been developed combining the digitalized archives from the Spanish Meteorological Agency (AEMET) with information retrieved from Annual Books published by the former Meteorological Agency dating back to 1916, and covers the period 1916-2015. In all four seasons, mean seasonal temperature of maximum (Tmax) and minimum (Tmin) increased. The raising occurred in two main pulses separated by a first pause around the middle of the 20th century, but differed among seasons and also between maximum and minimum temperature. Analysis of the percentage of land affected by significant trends in maximum temperature reveals two increasing phases in spring and summer for Tmax, and in spring, summer, and autumn for Tmin. However, winter Tmax only rose during the recent decades, and autumn Tmax in the first decades. Negative significant trends were found in extended areas in spring Tmax, and in spring, autumn, and summer Tmin, confirming the first pause around the 1940's-1960's. Trends of seasonal mean values of Tmax and Tmin are not significant for at least the last 25-35 years of the study period, depending on the season. The areas under significant positive trend are usually more extended for Tmin than Tmax at any season and period. Areas with significant trend expand and contract in time according to two spatial gradients: south‐east to north‐west (east‐west) for Tmax, and west to east for Tmin. We hypothesize a relationship between atmospheric prevalent advection and relief as triggering factors to understand spatial and temporal differences in seasonal temperatures at regional scale during the 20th century in the Iberian Peninsula