Machine learning techniques applied to multiband spectrum sensing in cognitive radios

This research received funding of the Mexican National Council of Science and Technology (CONACYT), Grant (no. 490180). Also, this work was supported by the Program for Professional Development Teacher (PRODEP).In this work, three specific machine learning techniques (neural networks, expectation maximization and k-means) are applied to a multiband spectrum sensing technique for cognitive radios. All of them have been used as a classifier using the approximation coefficients from a Multiresolution Analysis in order to detect presence of one or multiple primary users in a wideband spectrum. Methods were tested on simulated and real signals showing a good performance. The results presented of these three methods are effective options for detecting primary user transmission on the multiband spectrum. These methodologies work for 99% of cases under simulated signals of SNR higher than 0 dB and are feasible in the case of real signalsPeer ReviewedPostprint (published version

Comparaison de Méthodes de Compression Appliquées aux Electromyogrammes

Cet article traite de la compression des ElectroMyoGrammes (EMG). Le but de cet article est de présenter l'application de différentes méthodes de compression, afin de trouver la meilleure méthode adaptée aux EMG. Dans cet article, l'application des principales méthodes de compression sur l'EMG est étudiée : méthodes prédictives, méthodes par transformée, et plus spécifiquement méthodes basées sur la transformée en ondelette. Chacune des méthodes est brièvement exposée et les résultats obtenus sur des signaux réels sont présentés en fonction du Rapport Signal à Bruit et du Taux de Compression. Les résultats montrent que la méthode basée sur la transformée en ondelette s'avère être plus performante que les autres méthodes

Estudios de osmoiniciacion de semillas de cebolla de bulbo (allium cepa l.)

El presente trabajo se realizó durante el segundo semestre de 1996 y el primer semestre de 1997. Se dividió en dos etapas: la primera se realizó en los laboratorios de Fisiología Vegetal de la Universidad Nacional de Colombia, Facultad de Agronomía, en donde se establecieron los tratamientos de osmoiniciación; la segunda se realizó en los invernaderos del Centro de Investigaciones y Asesorías Agroindustriales de la Universidad Jorge Tadeo Lozano, en donde se establecieron los semilleros. En el ensayo se evaluaron 18 tratamientos de osmoiniciación utilizando PEG (6000) y KH2P04 en semillas de cebolla de bulbo (Allium cepa L.), con potenciales osmóticos de -0,5, -1,0 y -1,5 MPa, durante 5,10 y 15 días de imbibición. El diseño utilizado fue completamente al azar con arreglo factorial 2x3x3 y cuatro replicaciones. Se midieron las variables: 1) Porcentaje de germinación a los 5 días y a los 10 días, 2) porcentaje de emergencia a los 12 días, a los 17 días y a los 21 días, 3) Longitud de raíces, 4) Altura de planta, 5) Número de hojas, 6) Diámetro del bulbo, 7) Peso fresco y 8) Peso Seco. Se obtuvo mejor respuesta con el uso de KH2P04 en los porcentajes de germinación, en los porcentajes de emergencia y en la longitud de raíces.This trial was divided in two steps: the first step was conducted in the College of Agriculture, National University of Colombia, where the osmopriming treatment of onion seeds was conducted. The second step was carried out at the Research Center of the Jorge Tadeo Lozano University. Eighteen treatments of osmopriming were proved, by using PEG (6000) and KH2P04 with bulb onion seed (Allium cepa L.). Solutions with three osmotic potentials -0.5, -1.0 and -1.5 MPa were used and seeds were embebed for 5, 10 and 15 days. A Completely Randomized design with a factorial arrangement of 2x3x3 was used. The experiment was replicated four times. The variables measured wereo: 1) Percentage of germination 5 and 10 days after imbibition, 2)Percentage of emergence at 12,17 and 21 days after seeding, 3) Root length, 4) Plant height, 5) Number of leaves, 6) Bulb diameter, 7) Fresh weight, and 8) Dry weight. Percentage of germination, percentaqe of emergence and root length were higher withKH2P0

DISPOSITIVOS DE BAJO COSTO PARA EL ESTUDIO DE LOS SISTEMAS DE COMUNICACIÓN INALÁMBRICA (LOW-COST DEVICES FOR THE STUDY OF WIRELESS COMMUNICATION SYSTEMS)

ResumenLos equipos de laboratorio representan un costo considerable para cualquier institución educativa. Esto impacta el trabajo de investigación, pero sobre todo, limita la comprobación de los conocimientos teóricos en la práctica. Los cursos relacionados a telecomunicaciones requieren de equipo como analizadores de espectro para visualizar conceptos fundamentales, en especial en las comunicaciones inalámbricas. Sin embargo, el costo económico de este equipo lo hace difícil de adquirir. Con la aparición del radio definido por software (SDR) es posible adquirir dispositivos de bajo costo que pueden ser utilizados como analizadores de espectro.  Estos dispositivos conocidos como adaptadores RTL-SDR pueden reducir considerablemente el costo del equipo necesario en el laboratorio. En este trabajo se presentan los beneficios de considerar equipo basado en SDR en los laboratorios. También, se describen brevemente las opciones de hardware y software que pueden considerarse para mejorar el aprendizaje de las comunicaciones inalámbricas.Palabras Clave: Comunicaciones inalámbricas, dispositivos de bajo costo, equipo de laboratorio, radio definido por software.AbstractThe laboratory equipment represents a considerable cost for any educational institution. This impacts the research work, but most important, limits the verification of theoretical knowledge in practice. The courses related to telecommunications require equipment such as spectrum analyzers, to visualize fundamental concepts, especially in wireless communications. However, the economic cost of this equipment makes it difficult to acquire. With the appearance of software-defined radio (SDR), it is possible to acquire low-cost devices that can be used as spectrum analyzers. These devices known as RTL-SDR dongles can greatly reduce the cost of the equipment needed in the laboratory. This paper presents the benefits of considering equipment based on SDR in laboratories. Also, the hardware and software options that can be considered to improve the learning of wireless communications are briefly described.Keywords: Laboratory equipment, low-cost devices, software defined radio, wireless communications

Cooperative Multiband Spectrum Sensing Using Radio Environment Maps and Neural Networks

Cogitive radio networks (CRNs) require high capacity and accuracy to detect the presence of licensed or primary users (PUs) in the sensed spectrum. In addition, they must correctly locate the spectral opportunities (holes) in order to be available to nonlicensed or secondary users (SUs). In this research, a centralized network of cognitive radios for monitoring a multiband spectrum in real time is proposed and implemented in a real wireless communication environment through generic communication devices such as software-defined radios (SDRs). Locally, each SU uses a monitoring technique based on sample entropy to determine spectrum occupancy. The determined features (power, bandwidth, and central frequency) of detected PUs are uploaded to a database. The uploaded data are then processed by a central entity. The objective of this work was to determine the number of PUs, their carrier frequency, bandwidth, and the spectral gaps in the sensed spectrum in a specific area through the construction of radioelectric environment maps (REMs). To this end, we compared the results of classical digital signal processing methods and neural networks performed by the central entity. Results show that both proposed cognitive networks (one working with a central entity using typical signal processing and one performing with neural networks) accurately locate PUs and give information to SUs to transmit, avoiding the hidden terminal problem. However, the best-performing cognitive radio network was the one working with neural networks to accurately detect PUs on both carrier frequency and bandwidth.</jats:p

Seguridad alimentaria: la continua lucha contra las enfermedades de los cultivos

El instinto del ser humano es la búsqueda de alimentos y la conservación de los mismos a través del almacenamiento de frutos, granos y semillas para garantizar su alimentación en periodos de escasez. En este documento se abordan temas relacionados con los riesgos que tiene la producción de alimentos en campo por causa de fitopatógenos, algunos ejemplos históricos, estudios de diagnóstico y una propuesta a favor de la soberanía alimentaria. Las epifitias han mermado la producción en México y en el mundo provocando grandes catástrofes. Las hambrunas de Irlanda y Bengala son los hechos más devastadores para la humanidad, debido a que provocaron la muerte de más de tres millones de personas. Enfermedades causadas por patógenos emergentes se están presentando en la actualidad, amenazando la producción de alimentos y los rendimientos por unidad de superficie. Para combatirlos, es necesario un diagnóstico preciso mediante el uso de técnicas moleculares, la medición de la magnitud del daño, entre otras variables epidemiológicas, aunada a la aplicación de medidas fitosanitarias adecuadas. Con el propósito de asegurar el abasto de alimento para todos los mexicanos, en este trabajo se propone que instancias gubernamentales e instituciones de investigación realicen esfuerzos conjuntos, dirigidos al diseño de políticas fitosanitarias y a la investigación sobre patógenos de importancia económica. Este tipo de patógenos representan la mayor amenaza para nuestros cultivos, aunado al riesgo de su introducción debido a las importaciones. Además se propone implementar programas de gobierno permanentes para financiar la investigación sobre patógenos reglamentados

Methionine adenosyltransferase 1a antisense oligonucleotides activate the liver-brown adipose tissue axis preventing obesity and associated hepatosteatosis

Altered methionine metabolism is associated with weight gain in obesity. The methionine adenosyltransferase (MAT), catalyzing the first reaction of the methionine cycle, plays an important role regulating lipid metabolism. However, its role in obesity, when a plethora of metabolic diseases occurs, is still unknown. By using antisense oligonucleotides (ASO) and genetic depletion of Mat1a, here, we demonstrate that Mat1a deficiency in diet-induce obese or genetically obese mice prevented and reversed obesity and obesity-associated insulin resistance and hepatosteatosis by increasing energy expenditure in a hepatocyte FGF21 dependent fashion. The increased NRF2-mediated FGF21 secretion induced by targeting Mat1a, mobilized plasma lipids towards the BAT to be catabolized, induced thermogenesis and reduced body weight, inhibiting hepatic de novo lipogenesis. The beneficial effects of Mat1a ASO were abolished following FGF21 depletion in hepatocytes. Thus, targeting Mat1a activates the liver-BAT axis by increasing NRF2-mediated FGF21 secretion, which prevents obesity, insulin resistance and hepatosteatosis. High methionine and S-adenosylmethionine serum levels are related with obesity. Here the authors show that knockdown of methionine adenosyltransferase by using antisense oligonucleotides provides beneficial effects in obesity and comorbidities.This work was supported by Ayudas para apoyar grupos de investigacion del sistema Universitario Vasco (IT971-16) and MCIU/AEI/FEDER, UE (RTI2018-095134-B-100) (to P.A.), (RTI2018-099413-B-I00 and RED2018-102379-T) (to R.N.), PID2020119486RB-100 (to M.V.R.) and (RTI2018-096759-A-100) (to T.C.D). EFSD/Lilly European Diabetes Research Program, MICIU (PID2019-104399RB-I00), Fundacion AECC PROYE19047SABI, and Comunidad de Madrid IMMUNOTHERCAN-CM B2017/BMD-3733 (to G.S.). La CAIXA Foundation LCF/PR/HP17/52190004, MINECO-FEDER SAF2017-87301-R, AYUDAS FUNDACION BBVA A EQUIPOS DE INVESTIGACION CIENTIFICA UMBRELLA 2018 and AECC Scientific Foundation, grant name: Rare Cancers 2017 (to M.L.M.-C.). AECC Scientific Foundation (to T.C.D.). Xunta de Galicia 2020-PG015 (to R.N.) Gilead Sciences International Research Scholars Program in Liver Disease (to M.V.R.). Personal fellows: E.P.F. was awarded with Juan de la Cierva-Formacion, FJC2018-035449-I. C.F. was awarded with Sara Borrell (CD19/00078). CIC bioGUNE thanks MCIU for the Severo Ochoa Excellence Accreditation (SEV-2016-0644). The authors thank Dr. Manuel Lafitas laboratory (Getxo, Bizkaia, Spain) for his valuable help in the analysis of biochemical parameters

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10&nbsp;years; 78.2% included were male with a median age of 37&nbsp;years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020