Toward Reliable Compact Modeling of Multilevel 1T-1R RRAM Devices for Neuromorphic Systems

The authors would like to thank the financial support by Deutsche Forschungsgemeinschaft (German Research Foundation) with Project-ID SFB1461 and by the Federal Ministry of Education and Research of Germany under grant numbers 16ES1002, 16FMD01K, 16FMD02 and 16FMD03. The authors also gratefully acknowledge the support of the Spanish Ministry of Science, Innovation and Universities and the FEDER program through project TEC2017-84321-C4-3-R and project A.TIC.117.UGR18 funded by the government of Andalusia (Spain) and the FEDER program. The publication of this article was funded by the Open Access Fund of the Leibniz Association.The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.In this work, three different RRAM compact models implemented in Verilog-A are analyzed and evaluated in order to reproduce the multilevel approach based on the switching capability of experimental devices. These models are integrated in 1T-1R cells to control their analog behavior by means of the compliance current imposed by the NMOS select transistor. Four different resistance levels are simulated and assessed with experimental verification to account for their multilevel capability. Further, an Artificial Neural Network study is carried out to evaluate in a real scenario the viability of the multilevel approach under study.German Research Foundation (DFG) SFB1461Federal Ministry of Education & Research (BMBF) 16ES1002 16FMD01K 16FMD02 16FMD03Spanish Ministry of Science, Innovation and UniversitiesEuropean Commission TEC2017-84321-C4-3-Rgovernment of Andalusia (Spain) A.TIC.117.UGR18Leibniz Associatio

Optimization of Multi-Level Operation in RRAM Arrays for In-Memory Computing

Accomplishing multi-level programming in resistive random access memory (RRAM) arrays with truly discrete and linearly spaced conductive levels is crucial in order to implement synaptic weights in hardware-based neuromorphic systems. In this paper, we implemented this feature on 4-kbit 1T1R RRAM arrays by tuning the programming parameters of the multi-level incremental step pulse with verify algorithm (M-ISPVA). The optimized set of parameters was assessed by comparing its results with a non-optimized one. The optimized set of parameters proved to be an effective way to define non-overlapped conductive levels due to the strong reduction of the device-to-device variability as well as of the cycle-to-cycle variability, assessed by inter-levels switching tests and during 1k reset-set cycles. In order to evaluate this improvement in real scenarios, the experimental characteristics of the RRAM devices were captured by means of a behavioral model, which was used to simulate two different neuromorphic systems: an 8×8 vector-matrixmultiplication (VMM) accelerator and a 4-layer feedforward neural network for MNIST database recognition. The results clearly showed that the optimization of the programming parameters improved both the precision of VMM results as well as the recognition accuracy of the neural network in about 6% compared with the use of non-optimized parameters.German Research Foundation (DFG) - FOR2093Government of Andalusia (Spain) and the FEDER program in the frame of the project A.TIC.117.UGR18Open Access Fund of the Leibniz Associatio

Optimización de los métodos y procedimientos de calibración de termohigrómetros en el Centro Regional de Instrumentos de Buenos Aires

Fil: Aranda, Natalí Giselle. Servicio Meteorológico Nacional. Dirección Nacional de Infraestructura y Datos. Dirección de Redes de Observación; Argentina.Fil: Napán Maldonado, Rocio. Instituto Nacional de Tecnología Industrial; ArgentinaFil: García Skabar, Javier. Instituto Nacional de Tecnología Industrial; ArgentinaEl rol de los Centros Regionales de Instrumentos (CRI), es garantizar la calidad y trazabilidad de las mediciones meteorológicas. El CRI de Buenos Aires cuenta con un laboratorio en el que se realizan las calibraciones de los instrumentos meteorológicos. El Servicio Meteorológico Nacional (SMN) en colaboración con el Instituto Nacional de Tecnología Industrial de Argentina (INTI) puso en marcha un plan para mejorar las capacidades del laboratorio del CRI de Buenos Aires. Entre las medidas adoptadas, se encuentra la adquisición de una moderna cámara climática y la actualización de procedimientos de calibración, incorporando el análisis de las fuentes de incertidumbre. Las calibraciones se realizan dentro del rango de temperatura entre -30 °C a 50 °C sin control de humedad relativa a temperaturas inferiores a los 10 °C, y en el rango de humedad relativa entre 15% HR y 95% HR con control de temperatura. En este trabajo se describe el desarrollo y la metodología de calibración, implementada en el SMN, en temperatura y humedad relativa de sensores con indicador digital utilizando la cámara climática.The role of Regional Instrument Centres (RICs) is to guarantee meteorological measurements’ quality and traceability. RIC in Buenos Aires has a laboratory where calibrations of meteorological instruments are done. The National Meteorological Service of Argentina (SMN) in conjunction with The National Institute of Industrial Technology of Argentina (INTI) elaborated a plan to improve its laboratory's capabilities. Some of the measures taken are the purchase of a modern climatic chamber and the update of calibration procedures, by the budget uncertainty analysis. Calibrations are made in a temperature range between -30 °C to 50 °C without control of relative humidity for temperature values below 10 °C, and the relative humidity range is from 15% HR to 95% HR, controlling the temperature. In this study, the methodology implemented by the SMN and the analysis for digital thermometer and thermohygrometer calibrations in the climatic chamber, are described

TiN/Ti/HfO2/TiN memristive devices for neuromorphic computing: from synaptic plasticity to stochastic resonance

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fnins.2023. 1271956/full#supplementary-materialFunding The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. The authors thank the support of the Consejeria de Conocimiento, Investigacion y Universidad, Junta de Andalucia (Spain), and the FEDER program through project B-TIC-624-UGR20. They also thank the support of the Federal Ministry of Education and Research of Germany under Grant 16ME0092.We characterize TiN/Ti/HfO2/TiN memristive devices for neuromorphic computing. We analyze different features that allow the devices to mimic biological synapses and present the models to reproduce analytically some of the data measured. In particular, we have measured the spike timing dependent plasticity behavior in our devices and later on we have modeled it. The spike timing dependent plasticity model was implemented as the learning rule of a spiking neural network that was trained to recognize the MNIST dataset. Variability is implemented and its influence on the network recognition accuracy is considered accounting for the number of neurons in the network and the number of training epochs. Finally, stochastic resonance is studied as another synaptic feature. It is shown that this effect is important and greatly depends on the noise statistical characteristics.Consejería de Conocimiento, Investigación y Universidad, Junta de Andalucía (Spain), and the FEDER program through project B-TIC-624-UGR20Federal Ministry of Education and Research of Germany under Grant 16ME009

Spiking neural networks based on two-dimensional materials

The development of artificial neural networks using memristors is gaining a lot of interest among technological companies because it can reduce the computing time and energy consumption. There is still no memristor, made of any material, capable to provide the ideal figures-of-merit required for the implementation of artificial neural networks, meaning that more research is required. Here we present the use of multilayer hexagonal boron nitride based memristors to implement spiking neural networks for image classification. Our study indicates that the recognition accuracy of the network is high, and that can be resilient to device variability if the number of neurons employed is large enough. There are very few studies that present the use of a two-dimensional material for the implementation of synapses of different features; in our case, in addition to a study of the synaptic characteristics of our memristive devices, we deal with complete spiking neural network training and inference processes.Ministry of Science and Technology, China 2018YFE0100800National Natural Science Foundation of China (NSFC) 61874075Collaborative Innovation Centre of Suzhou Nano Science TechnologyPriority Academic Program Development of Jiangsu Higher Education Institutions111 Project from the State Administration of Foreign Experts Affairs of ChinaJunta de AndaluciaEuropean Commission A-TIC-117-UGR18 B-TIC-624-UGR20 IE2017-5414Spanish GovernmentERDF fund RTI2018-098983-B-I00King Abdullah University of Science & Technolog

El Turismo Rural y su Incidencia en el Desarrollo Sostenible en el Distrito de Antioquia – Huarochirí Región Lima Provincias 2018

El presente trabajo de investigación, titulado ¨El Turismo Rural y su Incidencia en el Desarrollo Sostenible en el Distrito de Antioquia – Huarochirí Región Lima Provincias 2018¨, tiene como objetivo general analizar, evaluar y determinar con una visión más clara la situación actual del turismo rural y su incidencia en el desarrollo sostenible del distrito asimismo recomendamos las acciones más apropiadas que podrían poner en marcha a fin de responder a las necesidades de la población y de los visitantes, anticiparse a los cambios del entorno y mejorar la posición que han adquirido en el mercado turístico. Para dicha investigación, se realizó un análisis del distrito de Antioquia y sus anexos donde se evaluaron la planta turística, los servicios complementarios, los recursos y atractivos turísticos, las opiniones de los turistas, el compromiso de la comunidad, los actores implicados: a) gobierno local. b) comunidad. c) Turistas. Nuestra investigación propone para el distrito de Antioquia recomendaciones de mejora y de implementación del sector turismo, el territorio, el producto turístico, la comercialización de sus productos autóctonos, la promoción y la comunicación entre los actores principales. Logrando poner en valor los recursos turísticos así como conservarlos, situar al distrito como un destino turístico aledaño a Lima ideal para escapar de la rutina, en un ambiente rural y natural con alternativas de realizar actividades de aventura, en donde el beneficiado sea la población visitada y el visitante, de esta forma se promoverá el desarrollo turístico rural sostenible esperado.The present research work, entitled "Rural Tourism and its Impact on Sustainable Development in the District of Antioquia - Huarochirí Lima Region Provinces 2018", has as its general objective to analyze, evaluate and determine with a clearer vision the current situation of tourism and its impact on the sustainable development of the district, we also recommend the most appropriate actions that could be implemented in order to respond to the needs of the population and visitors, anticipate changes in the environment and improve the position they have acquired in the tourist market. For this research, an analysis of the district of Antioquia and its annexes where the tourist plant, complementary services, resources and tourist attractions, the opinions of tourists, the commitment of the community, the involved actors were evaluated: a) local government. b) Community. c) Tourists. Our research proposes for the district of Antioquia recommendations for improvement and implementation of the tourism sector, the territory, the tourist product, the commercialization of its native products, the promotion and communication between the main actors. Achieving the value of tourism resources and keeping them, place the district as a tourist destination near Lima ideal to escape from routine, in a rural and natural environment with alternatives to carry out adventure activities, where the beneficiary is the population visited and the visitor, in this way the expected sustainable rural tourism development will be promoted.Trabajo de investigació

Genetic analysis of 17 Y-STRs in a Mestizo population from the Central Valley of Mexico

This study aims to portray the complex diversity of the Mexican Mestizo population, which represents 98.8% of the entire population of Mexico. We compiled extended haplotype data of the Y chromosome from populations in the Central Valley of Mexico (CVM), which were compared to other Mestizo and parental (Amerindian, European and African) populations. A complex ancestral relationship was found in the CVM population, suggesting cosmopolitan origins. Nevertheless, the most preeminent lineages point towards a European ancestry, where the R1b was the most frequent. In addition, important frequencies of Amerindian linages were also found in the Mestizo sample studied. Interestingly, the Amerindian ancestry showed a remarkable substructure, which was represented by the two main founding lineages: QL54 (x M3) and M3. However, even within each lineage a high diversity was found despite the small number of samples bearers of these lineages. Further, we detected important genetic differences between the CVM populations and the Mexican Mestizo populations from the north and south. This result points to the fact that Mestizo populations present different ancestral proportions, which are related to the demographic events that gave origin to each population. Finally, we provide additional forensic statistical parameters that are useful in the interpretation of genetic analysis where autosomal loci are limited. Our findings illustrate the complex genetic background of the Mexican Mestizo population and reinforce the need to encompass more geographic regions to generate more robust data for forensic applications

Genome and secretome of Chondrostereum purpureum correspond to saprotrophic and phytopathogenic life styles

We thank R. Ullrich for his mycological expertise and K. Eismann for useful technical assistance.The basidiomycete Chondrostereum purpureum (Silverleaf fungus) is a saprotroph and plant pathogen commercially used for combatting forest “weed” trees in vegetation management. However, little is known about its lignocellulose-degrading capabilities and the enzymatic machinery that is responsible for the degradative potential, and it is not yet clear to which group of wood-rot fungi it actually belongs. Here, we sequenced and analyzed the draft genome of C. purpureum (41.2 Mbp) and performed a quantitative proteomic approach during growth in submerged and solid-state cultures based on soybean meal suspension or containing beech wood supplemented with phenol-rich olive mill residues, respectively. The fungus harbors characteristic lignocellulolytic hydrolases (GH6 and GH7) and oxidoreductases (e.g. laccase, heme peroxidases). High abundance of some of these genes (e.g. 45 laccases, nine GH7) can be explained by gene expansion, e.g. identified for the laccase orthogroup ORTHOMCL11 that exhibits a total of 18 lineage-specific duplications. Other expanded genes families encode for proteins more related to a pathogenic lifestyle (e.g. protease and cytochrome P450s). The fungus responds to the presence of complex growth substrates (lignocellulose, phenolic residues) by the secretion of most of these lignocellulolytic and lignin-modifying enzymes (e.g. alcohol and aryl alcohol oxidases, laccases, GH6, GH7). Based on the genetic and enzymatic constitution, we consider the ‘marasmioid’ fungus C. purpureum as a ‘phytopathogenic’ white-rot fungus (WRF) that possesses a complex extracellular enzyme machinery to accomplish efficient lignocellulose degradation during both saprotrophic and phytopathogenic life phases.The work was financially and scientifically supported by the European Union [integrated projects INDOX – KBBE-7-2013-613549; ENZOX2 – 720297], by the DFG project PeroxiDiv HO 1961/8-1 and the AiF project PeroxyMEER IGF 19636 BG/3. The work has been partly funded by the DFG Priority Program 1374 "Infrastructure-Biodiversity-Exploratories" with the projects HO 1961/6-1, KE 1742/2-1 and JE 724/7-4 (AOBJ: 635952) and the Spanish Ministry of Economy and Competitiveness [project AGL2012-32873]. RR thanks the JAE-Program of the Spanish National Research Council [CSIC] and EA thanks MINECO and FEDER Co-Funds [RyC-2013-12481]

Multivariate analysis and extraction of parameters in resistive RAMs using the Quantum Point Contact model

A multivariate analysis of the parameters that characterize the reset process in RRAMs has been performed. The different correlations obtained can help to shed light on the current components that contribute in the Low Resistance State (LRS) of the technology considered. In addition, a screening method for the Quantum Point Contact (QPC) current component is presented. For this purpose the second derivative of the current has been obtained using a novel numerical method which allows determining the QPC model parameters. Once the procedure is completed, a whole RS series of thousands of curves is studied by means of a genetic algorithm. The extracted QPC parameter distributions are characterized in depth to get information about the filamentary pathways associated with LRS in the low voltage conduction regime.Spanish Ministry of Economy and Competitiveness TEC2014-52152-C3-2-R , MTM2013-47929-P (also supported by the FEDER program)IMB-CNM Spanish Ministry of Economy and Competitiveness TEC2014-52152-C3-1-R and TEC2014-54906-JIN (supported by the FEDER program)ENIAC Joint Undertaking-PANACHE project.Spanish ICTS Network MICRONANOFAB