15 research outputs found
Revealing networks from dynamics: an introduction
What can we learn from the collective dynamics of a complex network about its
interaction topology? Taking the perspective from nonlinear dynamics, we
briefly review recent progress on how to infer structural connectivity (direct
interactions) from accessing the dynamics of the units. Potential applications
range from interaction networks in physics, to chemical and metabolic
reactions, protein and gene regulatory networks as well as neural circuits in
biology and electric power grids or wireless sensor networks in engineering.
Moreover, we briefly mention some standard ways of inferring effective or
functional connectivity.Comment: Topical review, 48 pages, 7 figure
Inferring network connectivity from event timing patterns
Reconstructing network connectivity from the collective dynamics of a system
typically requires access to its complete continuous-time evolution although
these are often experimentally inaccessible. Here we propose a theory for
revealing physical connectivity of networked systems only from the event time
series their intrinsic collective dynamics generate. Representing the patterns
of event timings in an event space spanned by inter-event and cross-event
intervals, we reveal which other units directly influence the inter-event times
of any given unit. For illustration, we linearize an event space mapping
constructed from the spiking patterns in model neural circuits to reveal the
presence or absence of synapses between any pair of neurons as well as whether
the coupling acts in an inhibiting or activating (excitatory) manner. The
proposed model-independent reconstruction theory is scalable to larger networks
and may thus play an important role in the reconstruction of networks from
biology to social science and engineering.Comment: 6 pages, 5 figures, The first two authors contributed equally to this
paper, and should be regarded as co-first authors. [v2: metadata update
Estudio de factibilidad para la creación de la empresa porkys sport en la ciudad de ocaña (n. De. S)
Hecho el análisis de que en la ciudad de Ocaña, la actividad deportiva tiene amplia cobertura y de que en la misma, no existe una empresa que fabrique las prendas propias de dicho quehacer, en una forma técnica y organizada se optó por elaborar este estudio que contempló la viabilidad de crearla. La empresa en mención tendrá como objetivo primordial el ofrecimiento de prendas de vestir deportivas de optima calidad, en cuanto a: telas, mano de obra y accesorios. La adecuada infraestructura, gerencia y administración personal, la harán competitiva frente a las demás del ramo, de renombre en el país.
El presente proyecto se compone esencialmente de los estudios de mercado, técnico, financiero y económico. Adicionalmente se expone la monografía general del municipio de Ocaña, donde se localizará productivamente el proyecto.
Lo fundamental del estudio de mercado, es la viabilidad de creación de la empresa Porkys Sport, medida por la aceptación de los productos por parte del mercado potencial, la cual se concreta con el análisis de la demanda y la oferta. En el primero, se determinan las características del producto en general, la descripción del mercado, del proveedor, competidor, distribuidor y consumidor; también se estudia el comportamiento de la demanda teniendo en cuenta el índice de crecimiento de la población, permitiendo esta forma, la aproximación a un volumen de demanda actual de la confección de prendas deportivas. El segundo determina, la capacidad productiva de las mismas prendas en Ocaña. Se destaca así mismo la comercialización del producto, la determinación del precio y la publicidad.
En el estudio técnico se determina el tamaño del proyecto que hechos los cálculos respectivos alcanza a valores de : 8344, 8894, 9460, 10042, 10627 unidades para los cinco años de horizonte del mismo; de igual forma se explica la localización óptima del proyecto, sus ventajas y desventajas, el requerimiento y la descripción de insumos y del proceso productivo. Finalmente se configura la distribución de la planta y la cuantificación de los costos iniciales del proyecto.
Con el estudio financiero se define el costo de la inversión en general, que alcanza un valor de 13.348.850, se determina el financiamiento de la empresa cuyo monto asciende a 53. 902.850 el capital de trabajo calculado en 23.183.926 como también el punto de equilibrio, el cual queda determinado en 2520, unidades . Se concluye con al evaluación del proyecto para un periodo de cinco años, los ingresos y costos, se reflejan en un flujo de fondos con y sin financiamiento. Con los resultados del flujo se procede a las respectivas evaluaciones financieras utilizando para ello dos métodos que tienen en cuenta el valor del dinero en el tiempo como son el V.P.N y la TIR cuyo valor con financiamiento es de 76% y sin financiamiento de 92.63%. Finalmente se reordenan los flujos de fondos cambiando algunas variables ( costos, ventas) y se realiza el análisis de sensibilidad con el fin de hacer el proyecto más práctico
Model-free inference of direct network interactions from nonlinear collective dynamics
The topology of interactions in network dynamical systems fundamentally
underlies their function. Accelerating technological progress creates massively
available data about collective nonlinear dynamics in physical, biological, and
technological systems. Detecting direct interaction patterns from those
dynamics still constitutes a major open problem. In particular, current
nonlinear dynamics approaches mostly require to know a priori a model of the
(often high dimensional) system dynamics. Here we develop a model-independent
framework for inferring direct interactions solely from recording the nonlinear
collective dynamics generated. Introducing an explicit dependency matrix in
combination with a block-orthogonal regression algorithm, the approach works
reliably across many dynamical regimes, including transient dynamics toward
steady states, periodic and non-periodic dynamics, and chaos. Together with its
capabilities to reveal network (two point) as well as hypernetwork (e.g., three
point) interactions, this framework may thus open up nonlinear dynamics options
of inferring direct interaction patterns across systems where no model is
known.Comment: 10 pages, 7 figure
Inferring Topology of Networks With Hidden Dynamic Variables
Inferring the network topology from the dynamics of interacting units constitutes a topical challenge that drives research on its theory and applications across physics, mathematics, biology, and engineering. Most current inference methods rely on time series data recorded from all dynamical variables in the system. In applications, often only some of these time series are accessible, while other units or variables of all units are hidden, i.e. inaccessible or unobserved. For instance, in AC power grids, frequency measurements often are easily available whereas determining the phase relations among the oscillatory units requires much more effort. Here, we propose a network inference method that allows to reconstruct the full network topology even if all units exhibit hidden variables. We illustrate the approach in terms of a basic AC power grid model with two variables per node, the local phase angle and the local instantaneous frequency. Based solely on frequency measurements, we infer the underlying network topology as well as the relative phases that are inaccessible to measurement. The presented method may be enhanced to include systems with more complex coupling functions and additional parameters such as losses in power grid models. These results may thus contribute towards developing and applying novel network inference approaches in engineering, biology and beyond
Diseño de una red de sensores inalámbricos para el despliegue óptimo de los nodos sensores en un cultivo de Cacao
In this study, factorial experiments were conducted in two different scenarios to design a Wireless Sensor Network for monitoring a cocoa crop in a rural area in Colombia. Node sensors measured temperature, relative humidity, soil moisture, Ultra-Violet light, and visible light intensity. The factors considered in the experiments were distance between node sensors, height from the ground, and type of antenna; in turn, Received Signal Strength Indicator and data transfer time were the outputs. The wireless sensor network was deployed in the crop, covering approximately 3 % of the area and using 7 different nodes in a cluster tree topology. First, an open field scenario with line of sight was used to determine the appropriate height of the node sensors. Second, a scenario in the actual cocoa crop was utilized to find the appropriate distance between modules and type of antenna. We found, based on our calculations and experimental data, that a height of 1.25 m was required to avoid the Fresnel zone and improve the RSSI of the network. Furthermore, we determined that a distance below 35 m was needed to guarantee signal reception and avoid long data transfer times. The wire antenna exhibited a better performance. Finally, the proposed methodology and monitoring system can be used for agronomic applications in rural areas in Colombia to increase crop yield.En este trabajo se realizaron experimentos factoriales en dos escenarios diferentes, para diseñar una red de sensores inalámbricos, que permita monitorear un cultivo de cacao en una zona rural de Colombia. Los nodos sensores miden la temperatura, la humedad relativa, la humedad del suelo, la luz ultravioleta y la intensidad de la luz visible. Los factores considerados en los experimentos fueron la distancia entre los nodos sensores, la altura con respecto al suelo y el tipo de antena; el indicador de intensidad de señal recibida y el tiempo de transferencia de datos fueron las salidas. La red de sensores inalámbricos se implementó en el cultivo, cubriendo aproximadamente el 3 % del área, utilizando 7 nodos diferentes en una topología de cluster-tree. En primer lugar, se utilizó un escenario de campo abierto con línea de vista para determinar la altura adecuada de los sensores de nodo. Luego, se utilizó un escenario en el cultivo de cacao real para encontrar la distancia adecuada entre los módulos y el tipo de antena. Se obtuvo, por cálculos y datos experimentales, que se requería una altura de 1.25 m para evitar la zona de Fresnel y mejorar el RSSI de la red. Además, se determinó que se necesitaba una distancia inferior a 35 m para garantizar la recepción de la señal y evitar largos tiempos de transferencia de datos. Adicionalmente, la antena tipo Wire exhibió un mayor rendimiento y la metodología propuesta y el sistema de monitoreo se pueden usar para aplicaciones agronómicas en áreas rurales de Colombia, con el fin de aumentar el rendimiento de los cultivos
Control adaptativo para optimizar una intersección semafórica basado en un sistema embebido
In order to optimize the traffic flow on a road intersection, an adaptive control algorithm and a data base were designed; both components were hosted on a Raspberry Pi B+ embedded system. The data base helps to debug the performance of the controller. The efficiency of the algorithm was assessed using a virtual instrument, which emulated a traffic light intersection in the city of Cucuta, i. e., the magnetorresistive sensors, the activation process of the traffic lights and the traffic flow. By processing and updating the times assigned to the traffic lights, the traffic flow was increased up to 5.5 % and the maximum time a vehicle has to wait before passing through the traffic light was decreased up to 28 seconds. Aditionally the length of line was diminished up to 18 %. Based on this case study, it can be inferred that is possible to integrate the adaptive control and the embedded systems as software and hardware tools to improve the operation of traffic control systems.Para optimizar el flujo vehicular en una intersección vial se diseñaron un algoritmo de control adaptativo y una base de datos que apoya la depuración del rendimiento del controlador, ambos alojados en el sistema embebido Raspberry Pi B+. El desempeño del algoritmo fue evaluado con un instrumento virtual, que emuló una intersección semafórica de la ciudad de Cúcuta, esto es, los sensores magnetorresistivos, el proceso de encendido en las luces de los semáforos y el flujo vehicular. La manipulación de los tiempos de encendido en las luces de los semáforos, aumentó el flujo vehicular hasta 5.5% y, disminuyó el tiempo máximo de espera del vehículo para avanzar hasta 28 segundos y el largo de fila hasta un 18%. Con base en el caso de estudio, se puede inferir que es posible integrar el control adaptativo y los sistemas embebidos como herramientas de software y hardware para mejorar el funcionamiento en los sistemas de regulación vial
Effect of viral storm in patients admitted to intensive care units with severe COVID-19 in Spain: a multicentre, prospective, cohort study
Background: The contribution of the virus to the pathogenesis of severe COVID-19 is still unclear. We aimed to evaluate associations between viral RNA load in plasma and host response, complications, and deaths in critically ill patients with COVID-19. Methods: We did a prospective cohort study across 23 hospitals in Spain. We included patients aged 18 years or older with laboratory-confirmed SARS-CoV-2 infection who were admitted to an intensive care unit between March 16, 2020, and Feb 27, 2021. RNA of the SARS-CoV-2 nucleocapsid region 1 (N1) was quantified in plasma samples collected from patients in the first 48 h following admission, using digital PCR. Patients were grouped on the basis of N1 quantity: VIR-N1-Zero ([removed]2747 N1 copies per mL). The primary outcome was all-cause death within 90 days after admission. We evaluated odds ratios (ORs) for the primary outcome between groups using a logistic regression analysis. Findings: 1068 patients met the inclusion criteria, of whom 117 had insufficient plasma samples and 115 had key information missing. 836 patients were included in the analysis, of whom 403 (48%) were in the VIR-N1-Low group, 283 (34%) were in the VIR-N1-Storm group, and 150 (18%) were in the VIR-N1-Zero group. Overall, patients in the VIR-N1-Storm group had the most severe disease: 266 (94%) of 283 patients received invasive mechanical ventilation (IMV), 116 (41%) developed acute kidney injury, 180 (65%) had secondary infections, and 148 (52%) died within 90 days. Patients in the VIR-N1-Zero group had the least severe disease: 81 (54%) of 150 received IMV, 34 (23%) developed acute kidney injury, 47 (32%) had secondary infections, and 26 (17%) died within 90 days (OR for death 0·30, 95% CI 0·16–0·55; p<0·0001, compared with the VIR-N1-Storm group). 106 (26%) of 403 patients in the VIR-N1-Low group died within 90 days (OR for death 0·39, 95% CI 0·26–0·57; p[removed]11 página