882 research outputs found
Negative electrospray ionisation of fluorotelomer alcohols (FTOH) and FTOH-derived acrylate surfactants by liquid chromatography coupled to accurate (tandem) mass spectrometry
Análisis estadístico de los resultados de una investigación de los efectos de la influencia de la contaminación atmosférica sobre indicadores biológicos en escolares de sexo masculino
Con el objeto de buscar indicadores biológicos humanos de los efectos de la contaminación atmosférica se ha ejecutado un proyecto analítico exploratorio con poblaciones escolares en el centro de la ciudad de Santiago y en la comuna rural de María Pinto (Región Metropolitana). Se trabajó con 114 voluntarios escolares varones entre 10 y 14 años en el Instituto Nacional en Santiago y con un grupo de conrtol, similar, de 51 escolares en María Pinto. En sangre venosa y saliva obtenidas de estos voluntarios se hicieron determinaciones de variables inmunológicas, hematológicas y bioquímicas y medición de la actividad fagocítica del macrófago de sangre periférica. Se hicieron igualmente determinaciones antropométricas. Se determinó también factores de contaminación atmosférica por partículas en ambos lugares: se comprobó que la calidad de aire es significativamente diferente en ellos. Se resumen los resultados globales del proyecto y su análisis estadístico: se discuten tres metodologías alternativas que permitirían tomar en cuenta diferencias de estado nutricional entre ambas poblaciones que pudieran afectar los niveles de respuesta en las variables principales. Las concentraciones de imnunoglobulinas y los factores de complementos C3 y C4 no se muestran como indicadores biológicos efectivos de la contaminación por partículas en la atmósfera. Subsiste la posibilidad de que las variables: capacidad antioxidante del plasma, metahemoglobina, hematocrito, concentración de Fe en materia seca de sangre y otras puedan servir como tales indicadores. Las variaciones conjuntas del índice de fagocitosis y del % de killing evidencian un significativo stress oxidativo
Magnetic Field Generation in Collisionless Shocks; Pattern Growth and Transport
We present results from three-dimensional particle simulations of
collisionless shocks with relativistic counter-streaming ion-electron plasmas.
Particles are followed over many skin depths downstream of the shock. Open
boundaries allow the experiments to be continued for several particle crossing
times. The experiments confirm the generation of strong magnetic and electric
fields by a Weibel-like kinetic streaming instability, and demonstrate that the
electromagnetic fields propagate far downstream of the shock. The magnetic
fields are predominantly transversal, and are associated with merging ion
current channels. The total magnetic energy grows as the ion channels merge,
and as the magnetic field patterns propagate down stream. The electron
populations are quickly thermalized, while the ion populations retain distinct
bulk speeds in shielded ion channels and thermalize much more slowly. These
results may help explain the origin of the magnetic fields responsible for
afterglow synchrotron/jitter radiation from Gamma-Ray Bursts.Comment: 4 pages, 6 figures - Accepted to ApJL. Revised version following
recommendations of referee report. Content reduced marginally. Conclusions
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Grain size analysis in permanent magnets from Kerr microscopy images using machine learning techniques
Understanding the relationships between composition, structure, processing and properties helps in the development of improved materials for known applications as well as for new applications. Materials scientists, chemists and physicists have researched these relationships for many years, until the recent past, by characterizing the bulk properties of functional materials and describing them with theoretical models.
Magnets are widly used in electric vehicles (EV), hybrid electric vehicles (HEV), data storage, power generation and transmission, sensors etc. The search for novel magnetic phases requires an efficient quantitative microstructure analysis of microstructural information like phases, grain distribution and micromagnetic structural information like domain patterns, and correlating the information with intrinsic magnetic parameters of magnet samples. The information out of micromagnetic domains helps in obtaining the optimized microstructures in magnets that have good intrinsic magnetic properties.
This paper is aimed at introducing the use of a traditional machine learning (ML) model with a higher dimensional feature set and a deep learning (DL) model to classify various regions in sintered NdFeB magnets based on Kerr-microscopy images. The obtained results are compared against reference data, which is generated manually by subject experts. Additionally, the results were compared against the approach for grain analysis, which is based on the electron backscatter diffraction (EBSD) technique. Further, the challenges faced by the traditional machine learning model for classifying microstructures in Kerr micrographs are discussed
Finding a third archetypal technical system in architectural phenomenology
Within the scope of phenomenology and in order to understand architecture, the role of the technical system is as important as those of the purpose of the building or its form. Mass construction and skeletal construction relate to the architectural theory concepts stereotomy and tectonics respectively, which are suitable for describing the fundamental structural and constructive form of architecture. These two systems became established as man built his first shelters and, so far, represented opposite sides of the building industry’s possibilities. The development of new construction techniques and the relationship between research and technology have a great impact on architecture, although new processing methods and materials may not necessarily cause genuine tectonic changes. The technical dimension of architecture is analysed in this work describing how technical elements are built from materials, and then organised in systems. First, the paper examines the division of technical systems in two categories (massive systems and skeletal systems); then it studies timber’s modern production technologies and subsequently the paper critically analyses how these influence the architectural form. The paper concludes that a third archetypal technical system can be perceived with the assembly of surface elements, joining both the multifunctional aspect of the massive systems and the flexibility of the skeletal systems, this third category being fundamental in phenomenological terms
ELM-induced cold pulse propagation in ASDEX Upgrade
In ASDEX Upgrade, the propagation of cold pulses induced by type-I edge localized modes (ELMs) is studied using electron cyclotron emission measurements, in a dataset of plasmas with moderate triangularity. It is found that the edge safety factor or the plasma current are the main determining parameters for the inward penetration of the T-e perturbations. With increasing plasma current the ELM penetration is more shallow in spite of the stronger ELMs. Estimates of the heat pulse diffusivity show that the corresponding transport is too large to be representative of the inter-ELM phase. Ergodization of the plasma edge during ELMs is a possible explanation for the observed properties of the cold pulse propagation, which is qualitatively consistent with non-linear magneto-hydro-dynamic simulations.Peer reviewe
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