763 research outputs found
A methodology for transient state estimation based on numerical derivatives, optimal monitoring and filtered measurements
This paper proposes a methodology for transient state estimation in power systems. The proposed methodology is formulated using approximation methods for derivatives to relate the state variables to measurements. It does not require knowledge of the steady state to establish the pre-disturbance operation conditions. The method uses an optimal monitoring system based on topological analysis to obtain full observability. A saving index is introduced to analyze the effectiveness of the instrumentation used. The adverse effect of noisy measurements in the estimation process is mitigated using an Infinite Impulse Response (IIR) filter. A transient index is introduced to estimate the fault location. The transient state estimation is assessed using two test systems. The results are validated through direct comparison against those obtained by simulation using SimPowerSystems toolbox of Simulink®. With the proposed methodology, the transient state estimation can be obtained with an important saving in the implementation of the measuring system and with considerably less computational effort
Chua´s circuit and its characterization as a filter
"This article deals with Chuaʼs circuit characterization from the point of view of a filter based on the concept of piecewise linear functions. Furthermore, experiments are developed for teaching electronic systems that can be used for novel filtering concepts. The frequency range in which they are tested is from to , due to the audio spectrum comprised in this frequency range. The node associated with the capacitor and Chuaʼs diode is used as input, and the node for another capacitor and the coil is used as output, thereby establishing one input–output relationship for each system case given by the piecewise linear functions. The experimental result shows that Chuaʼs circuit behaves as a bandpass filter-amplifier, with a maximum frequency around and bandwidth between and . The results presented in this paper can motivate engineering students to pursue applications of novel electrical circuits based on topics that are of potential interest in their future research studies.
Influence of anthropometry and body composition in climbing ability
INTRODUCTION: Climbing has become a popular, competitive and recreational sport. It requires, principally, skilled technique and high muscle strength. Therefore, it has been necessary to implement formal studies about the training of this discipline. Investigations have been performed some studies to demonstrate that the improvement of climbing can be explained with anthropometric and physiological variables. PURPOSE: The purpose of this study was evaluate the main variables that affect the performance of the climbing, namely, anthropometry, body composition and climbing level. METHODS: Eighteen climbers, ranged 22 - 40 years old and V2-V7 of climbing ability (according Hueco Tanks scale), were volunteered to participate. Measurements of anthropometric characteristics and body composition including height, arm spam, forearm maximum, midstylion-dactilion, lean arm mass, body mass index (BMI), skeletal muscle mass, body fat mass, visceral fat, were performed. All variables were evaluated by using a combination of a principal component analysis (PCA) with a cluster analysis. RESULTS: When the analysis was performed in both anthropometry (skeletal muscle mass, lean arm mass and forearm maximum) and body composition (BMI, body fat mass and visceral fat) groups of variables, the results showed an 86% of the variance. The anthropometry variables showed correlation with 60% of the total variance. Concretely, the higher climbing level athletes (V5-V7) showed a higher lean body mass and arm muscle mass than the lower climbing levels athletes (V0-V4). On the other hand, the last group showed higher body fat mass and visceral fat mass with respect to the V5-V7 climbing athletes. CONCLUSION: The data of the present study showed a clear tendency on the variables, both body composition and anthropometry, in terms of the climbing level. However, these results are not completely conclusive. We suggest necessary to improve the performance of the measurements in future studies
Contributions to the study of the foetal development of physiological intimal thickening in the human uterine artery
The morphological study of the development of ifintimal thickeningsll of the human uterine artery in physiological condition was performed on 72 uterine arteries obtained from foetuses from the 12 th week of gestation up to birth. Our results indicate that intimal thickening is formed by the migration and displacement of mesenchymal cells around the site of origin of collateral vessel from uterine mesothelium. These cells firstly differentiate into the myoblasts and then into the myocites. During the development the internal limitans membrane separates the intimal thickening from the tunica media and the elastic fibres appearing inside possessing a muscle-elastic nature.
The function of intimal thickenings is the regulation of local blood flow by means of the control of myocitic contractile capacity; these cells play a fundamental role in endothelium-intimal smooth muscle cell contact
Síntesis de ectomicorrizas entre Cistus sp. y las especies del complejo Boletus edulis
En los jarales resultantes de la reiteración de incendios forestales en el oeste de Castilla y León (León, Salamanca y Zamora) es habitual la presencia de fructificaciones de Boletus edulis Bull. La recolección de estos hongos micorrícicos comestibles en los jarales dominados exclusivamente por Cistus ladanifer, supone una oportunidad económica alternativa a los usos tradicionales para zonas con bajos ingresos procedentes del monte.
El objetivo de éste trabajo es la obtención de ectomicorrizas de las especies del complejo B. edulis con Cistus sp. bajo condiciones controladas, y las descripciones anatómicas detalladas de las mismas. La identificación de los aislados fúngicos de Boletus aereus Bull., B. edulis, B.
reticulatus Schaeff. y B. pinophilus Pilát & Dermek fue confirmada por métodos moleculares.
Se han obtenido ectomicorrizas de Boletus aereus, B. edulis y B. reticulatus con Cistus
albidus L. y C. ladanifer en condiciones de síntesis en cultivo puro, en un substrato de turbavermiculita estéril y solución nutritiva. Las ectomicorrizas formadas se describieron siguiendo los caracteres anatómicos y morfológicos habituales. Las tres ectomicorrizas son muy similares, de color blanco, con ramificación monopodial-pinnada, manto formado por tres capas plectenquimatosas y con rizomorfos de tipo boletoide
Evaluating the Response of Chemoradiation Combined with Immunotherapy in Treating Locally Advanced Cervical Cancer
https://openworks.mdanderson.org/sumexp23/1007/thumbnail.jp
ANTIMICROBIAL ACTIVITY OF MEDICINAL PLANTS FROM THE HUAUTLA SIERRA BIOSPHERE RESERVE IN MORELOS (MÉXICO)
Twenty-two extracts from nine Mexicanmedicinal plants of eight different familiesused for people neighbor to Huautla SierraBiosphere Reserve (REBIOSH) in differentinfectious diseases were assayed in vitro todetermine their antibacterial activity againstStaphylococcus aureus, Streptococcus faecalis; Escherichia coli; Proteus mirabilis;Salmonella typhi and the yeast Candidaalbicans. Most plants showed antibacterialactivity, while two plants showed activityagainst range 0.25 a 4 mg/mL almost onemicroorganism used. The extracts showedminimum inhibitory concentration (MIC)against S. aureus and S. faecalis, representsmicroorganisms Gram-positive were hexanic and acetonic extracts of Bursera copallifera and hexanic extract of B. grandifolia.The ethanol extract of Lippia graveolensshowed a MIC value of 1 mg/mL againstyeast Candida albicans.Se determinó la actividad antimicrobianade veintidós extractos orgánicos de nueveespecies vegetales medicinales de ochodiferentes familias, que son comúnmenteempleadas por los habitantes de las comunidades vecinas a la reserva de la biosferaSierra de Huautla (REBIOSH), Morelos,para tratar diferentes padecimientos infecciosos. Los microorganismos empleadosfueron: Staphylococcus aureus; Streptococcus faecalis; Escherichia coli; Proteusmirabilis; Salmonella typhi y la levaduraCandida albicans. La mayoría de los extractos de las plantas probadas inhibieronel crecimiento microbiano en un rango de0.25 a 4 mg/mL de al menos uno de losmicroorganismos utilizados. Los extractosque mostraron las menores concentracionesmínimas inhibitorias (CMI) frente a losmicroorganismos S. aureus y S. faecalis,representativos de Gram-positivos fueron el extracto hexánico y acetónico de Burseracopallifera y el hexánico de B. grandifolia.El extracto etanólico de Lippia graveolenslogró inhibir a C. albicans con una CMIde 1 mg/mL
P2X7 Receptors as a Therapeutic Target in Cerebrovascular Diseases
Shortage of oxygen and nutrients in the brain induces the release of glutamate and ATP that can cause excitotoxicity and contribute to neuronal and glial damage. Our understanding of the mechanisms of ATP release and toxicity in cerebrovascular diseases is incomplete. This review aims at summarizing current knowledge about the participation of key elements in the ATP-mediated deleterious effects in these pathologies. This includes pannexin-1 hemichannels, calcium homeostasis modulator-1 (CALHM1), purinergic P2X7 receptors, and other intermediaries of CNS injury downstream of ATP release. Available data together with recent pharmacological developments in purinergic signaling may constitute a new opportunity to translate preclinical findings into more effective therapies in cerebrovascular diseases.This study was supported by grants from CONACYT-Mexico No. 252121 and PAPIITUNAM-Mexico No. IN203519 to ROA laboratory; by Spanish Ministry of Education and Science/FEDER (SAF2016-75292-R), Basque Government (IT1203/19), CIBERNED, Eranet-Neuron and Universidad del Pais Vasco to CM's laboratory. AC-M is a researcher from Catedras-CONACYT commissioned at Instituto de Neurobiologia at Universidad Nacional Autonoma de Mexico (UNAM)
Applications of Carboxylic Acids in Organic Synthesis, Nanotechnology and Polymers
Carboxylic acids are versatile organic compounds. In this chapter is presented a current overview of the use of carboxylic acids in a different area as organic synthesis, nanotechnology, and polymers. The application carboxylic acids in these areas are: obtaining of small molecules, macromolecules, synthetic or natural polymers, modification surface of nanoparticles metallic, modification surface of nanostructure such as carbon nanotubes and graphene, nanomaterials, medical field, pharmacy, etc. Carboxylic acids can be natural and synthetic, can be extracted or synthesized, presented chemical structure highly polar, active in organic reactions, as substitution, elimination, oxidation, coupling, etc. In nanotechnology, the use of acid carboxylic as surface modifiers to promote the dispersion and incorporation of metallic nanoparticles or carbon nanostructure, in the area of polymer carboxylic acids present applications such monomers, additives, catalysts, etc. The purpose of this chapter is to emphasize the importance of carboxylic acids in different areas, highlighting the area of organic synthesis, nanotechnology and polymers and its applications
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