Selección de conexiones de acero para zonas sísmicas con base en criterios de confiabilidad

Los hallazgos encontrados a raíz del terremoto de Northridge en 1994 han atraído actualmente la atención de los especialistas, sobre todo en cuanto a los problemas de diseño y seguridad de las conexiones soldadas para estructuras ubicadas en zonas sísmicas. Para equilibrar la seguridad requerida deben tomarse decisiones en relación con los costos para prevenir la posibilidad de excederse algún estado límite de servicio. Las técnicas de confiabilidad estructural proporcionan el marco adecuado para incluir las incertidumbres inherentes en el proceso de diseño. La formulación propuesta permite apoyar a diseñadores y a constructores para la selección del tipo de conexión más conveniente para las zonas sísmicas.Los hallazgos encontrados a raíz del terremoto de Northridge en 1994 han atraído actualmente la atención de los especialistas, sobre todo en cuanto a los problemas de diseño y seguridad de las conexiones soldadas para estructuras ubicadas en zonas sísmicas. Para equilibrar la seguridad requerida deben tomarse decisiones en relación con los costos para prevenir la posibilidad de excederse algún estado límite de servicio. Las técnicas de conÀabilidad estructural proporcionan el marco adecuado para incluir las incertidumbres inherentes en el proceso de diseño. La formulación propuesta permite apoyar a diseñadores y a constructores para la selección del tipo de conexión más conveniente para las zonas sísmicas

Solitary electromechanical pulses in Lobster neurons

Investigations of nerve activity have focused predominantly on electrical phenomena. Nerves, however, are thermodynamic systems, and changes in temperature and in the dimensions of the nerve can also be observed during the action potential. Measurements of heat changes during the action potential suggest that the nerve pulse shares many characteristics with an adiabatic pulse. First experiments in the 1980s suggested small changes in nerve thickness and length during the action potential. Such findings have led to the suggestion that the action potential may be related to electromechanical solitons traveling without dissipation. However, they have been no modern attempts to study mechanical phenomena in nerves. Here, we present ultrasensitive AFM recordings of mechanical changes on the order of 2 - 12 {\AA} in the giant axons of the lobster. We show that the nerve thickness changes in phase with voltage change. When stimulated at opposite ends of the same axon, colliding action potentials pass through one another and do not annihilate. These observations are consistent with a mechanical interpretation of the nervous impulse.Comment: 9 pages, 4 figure

Reply to "Comment on 'Penetration of Action Potentials During Collision in the Median and Lateral Giant Axons of Invertebrates'"

Berg et al. did not reproduce our results but worked on different preparations and, in one central experiment, used a significantly different electrode configuration. To clarify the situation, we have repeated their experiment on the walking leg of a lobster using an apparatus that can produce both electrode configurations. With the configuration used by Berg et al., the signal of the nerve pulse disappears when forced to pass through the region strongly perturbed by the second stimulus. In our original collision setup, pulses do not travel through perturbed regions, and pulses pass through each other without annihilation as previously reported. These results demonstrate that we handle the preparations correctly. Furthermore, they call for a reinterpretation of the so-called collision block experiment performed by Berg et al. Most likely, their results merely indicate inhibition of the nerve pulse by a strong stimulus and not annihilation upon collision as claimed

Characterization of micromobility crashes in Spain (2016-2020)

Micromobility has a direct impact on the urban area, since it tries to make cities more liveable, o:ffering an alternative transport option that contributes to reduce air and noise pollution. Additionally, it promotes intennodality, promotes money savings, reduces parking space and helps to avoid road congestion in cities that have their own lanes for the use of micromobility vehicles such as bicycles, stand-up e-scooters (escooters) and other personal mobility vehicles (PMVs). In Spain, micromobility has significantly increased in recent years, through the increase in the supply and demand for bicycles and other PMVs, mainly e-scooters. There are many reasons that have motivated users to prioritize the bicycle and the other PMVs over other means of tra.nsport. In addition to the growing concern for health and the environment, the COVID-19 pandemic has also driven the growth in the use ofthe different PMVs in 2020. Accordmg to data from Global Public Transport Report, published by the mobility application Moovit, 31 % of Spanianis have used bicycles, scooters or e-scooters in 2020, increasing their use by 7% since 2019. However, in parallel and because of the increase in PMVs exposure, the number of crashes involving users of these vehicles has also increased in recent years. For this reason, among road safety researchers, interest and concern for the study of this kind of crashes have also increased The aim of this research is to characterize the crashes in Spain in which at least one PMV (bicycle, e-scooter or other PMV) is involved between the years 2016 and 2020

RENTABILIDAD DEL NOGAL PECANERO BAJO SISTEMAS DE PRODUCCIÓN DE MEDIANA TECNOLOGÃA EN DELICIAS, CHIHUAHUA

Pecans (Carya Illinoinensis [Wangenh] K. Koch) are a native food of North America and represent a high economic crop value in the north of Mexico, mainly in the state of Chihuahua, the biggest pecan nut producer in this country. The goal of this study was to evaluate the profitability of pecan orchards in the municipality of Delicias, Chihuahua. Some microeconomic and market information from 2008 were collected from pecan growers and specialists through the technique of Experts' Panel. Standard financial analysis and a Monte Carlo simulation model were used to evaluate the probabilities of risk for net cash income (NCI) and return on capital employed (RCE). The NCI obtained was $277,000 and RC 111.7%, indicating that pecan orchards show high profitability when is produced under medium-technology conditions in the municipality of Delicias, Chihuahua.Carya Illinoinensis, production costs, Monte Carlo simulation., Agribusiness,

body2vec: 3D Point Cloud Reconstruction for Precise Anthropometry with Handheld Devices

Current point cloud extraction methods based on photogrammetry generate large amounts of spurious detections that hamper useful 3D mesh reconstructions or, even worse, the possibility of adequate measurements. Moreover, noise removal methods for point clouds are complex, slow and incapable to cope with semantic noise. In this work, we present body2vec, a model-based body segmentation tool that uses a specifically trained Neural Network architecture. Body2vec is capable to perform human body point cloud reconstruction from videos taken on hand-held devices (smartphones or tablets), achieving high quality anthropometric measurements. The main contribution of the proposed workflow is to perform a background removal step, thus avoiding the spurious points generation that is usual in photogrammetric reconstruction. A group of 60 persons were taped with a smartphone, and the corresponding point clouds were obtained automatically with standard photogrammetric methods. We used as a 3D silver standard the clean meshes obtained at the same time with LiDAR sensors post-processed and noise-filtered by expert anthropological biologists. Finally, we used as gold standard anthropometric measurements of the waist and hip of the same people, taken by expert anthropometrists. Applying our method to the raw videos significantly enhanced the quality of the results of the point cloud as compared with the LiDAR-based mesh, and of the anthropometric measurements as compared with the actual hip and waist perimeter measured by the anthropometrists. In both contexts, the resulting quality of body2vec is equivalent to the LiDAR reconstruction.Fil: Trujillo Jiménez, Magda Alexandra. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Navarro, Pablo Eugenio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Pazos, Bruno Alfredo. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Morales, Arturo Leonardo. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; ArgentinaFil: Ramallo, Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Paschetta, Carolina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: de Azevedo, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Ruderman, Anahí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Perez, Luis Orlando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Delrieux, Claudio Augusto. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; ArgentinaFil: Gonzalez-Jose, Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; Argentin

3D-printed and injection molded polymer matrix composites with 2D layered materials

This article reports on a study where 2D TMDs (MoS₂ and WS₂) and the 3D allotrope of carbon and graphite were incorporated into acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate glycol (PETG) matrices in order to form polymer matrix composites (PMCs). The multipronged analysis described in this study was motivated by the purpose to fuse together topics of low-cost, additive manufacturing with 2D layered materials, and studying their ensuing mechanical and tribological properties