Search results for "Magnetisme"
showing 10 items of 24 documents
Collective hydrodynamic transport of magnetic microrollers
2021
We investigate the collective transport properties of microscopic magnetic rollers that propel close to a surface due to a circularly polarized, rotating magnetic field. The applied field exerts a torque to the particles, which induces a net rolling motion close to a surface. The collective dynamics of the particles result from the balance between magnetic dipolar interactions and hydrodynamic ones. We show that, when hydrodynamics dominate, i.e. for high particle spinning, the collective mean velocity linearly increases with the particle density. In this regime we analyse the clustering kinetics, and find that hydrodynamic interactions between the anisotropic, elongated particles, induce p…
La imagen del magnetismo animal en la literatura de ficción : los casos de Poe, Doyle y Du Maurier
2014
En el presente trabajo nos acercamos a la imagen social del fenómeno conocido como mesmerismo o magnetismo animal a través del análisis de las obras: The Facts in the Case of Mr. Valdemar (1845) de Edgar Allan Poe, The Great Keinplatz Experiment (1885) de Conan Doyle y Trilby (1894) de George Du Maurier. Mostraremos cuál es el estereotipo del magnetizador y los usos que observamos del mesmerismo. Nos acercaremos a los espacios y actores del trasunto mesmerico presentado en los relatos. Tendremos en cuenta la recepción por parte del público de estas historias y las relaciones con los conocimientos mesmericos e hipnóticos que tenían los autores de éstas. En la actualidad, investigadores acadé…
Opusculum ... de natura magnetis, et eius effectibus ... / Authore Ioanne Taisnierio Hannonio ...
1562
Sig. A-K4, L6 Els grav. xil. - Retrat de l'autor al verso de la port. i al final. - Grav. a la port. - Capitals grav. Reclams. - Errates de pag.: de la p. 44 passa a la 43, de la 82 a la 81, de la 81 a la 80
El modelo de Ausubel en la didáctica de la física : una aproximanción experimental al proceso de E/A de contenidos que presentan constructos poco ela…
1993
Resumen basado en el de la publicación Resumen en inglés Se muestran los resultados de una investigación sobre educación física sobre «Magnetismo» en la escuela secundaria. Se investiga un enfoque constructivista para el diseño instruccional basado en el modelo de Ausubel en el tratamiento de temas en el cual los alumnos tienen representaciones conceptuales pobres y marcos alternativos. Se muestran los primeros resultados con respecto al aprendizaje inmediato y duradero. ESP
Orientational dynamics of colloidal ribbons self-assembled from microscopic magnetic ellipsoids
2016
We combine experiments and theory to investigate the orientational dynamics of dipolar ellipsoids, which self-assemble into elongated ribbon-like structures due to the presence of a permanent magnetic moment, perpendicular to the long axis in each particle. Monodisperse hematite ellipsoids are synthesized via the sol-gel technique and arrange into ribbons in the presence of static or time-dependent magnetic fields. We find that under an oscillating field, the ribbons reorient perpendicular to the field direction, in contrast with the behaviour observed under a static field. This observation is explained theoretically by treating a chain of interacting ellipsoids as a single particle with or…
Experimental neutron capture data of 58Ni from the CERN n_TOF facility
2014
The $^{58}$Ni $(n,\gamma)$ cross section has been measured at the neutron time of flight facility n_TOF at CERN, in the energy range from 27 meV up to 400 keV. In total, 51 resonances have been analyzed up to 122 keV. Maxwellian averaged cross sections (MACS) have been calculated for stellar temperatures of kT$=$5-100 keV with uncertainties of less than 6%, showing fair agreement with recent experimental and evaluated data up to kT = 50 keV. The MACS extracted in the present work at 30 keV is 34.2$\pm$0.6$_\mathrm{stat}\pm$1.8$_\mathrm{sys}$ mb, in agreement with latest results and evaluations, but 12% lower relative to the recent KADoNIS compilation of astrophysical cross sections. When in…
Resonancias de ondas electromagnéticas
1994
Este artículo describe un conjunto de experimentos diseñados para medir las resonancias electromagnéticas de varios sistemas sencillos.
FILTER RESPONSE OF RESONANT WAVEGUIDE DIELECTRIC GRATINGS AT PLANE-WAVE CONICAL INCIDENCE
2009
An accurate and efficient formulation is presented for the electromagnetic analysis of dielectric waveguide gratings under plane-wave conical incidence. An arbitrary number of dielectric bars can be placed inside each one-dimension periodic cell, including the effect of dielectric losses. The reflectance of a dielectric waveguide grating under conical incidence is compared with theoretical results presented by other authors, finding a very good agreement. A single-layer reflection filter has been designed centered at λ0=1.5 μm whose spectral and angular responses are shown. For this structure, the effect of the asymmetry of the distribution of the refraction index in the reflectance has bee…
Subjective symptoms related to GSM radiation from mobile phone base stations : a cross-sectional study
2013
Objectives: We performed a reanalysis of the data from Navarro et al., 2003, in which health symptoms related to microwave exposure from mobile phone base stations (BS) were explored, including data obtained in a retrospective inquiry about fear of exposure from BS. Design: Cross-sectional study. Setting: La Ñora (Murcia), Spain. Participants: Participants with known illness in 2003 were subsequently disregarded: 88 participants instead of 101 (in 2003) were analysed. Since weather circumstances can influence exposure, we restricted data to measurements made under similar weather conditions. Outcomes and methods: A statistical method indifferent to the assumption of normality was employed: …
Emergence of the stripe-domain phase in patterned permalloy films
2016
The occurrence of stripe domains in ferromagnetic Permalloy (Py=Fe$_{20}$Ni$_{80}$) is a well known phenomenon which has been extensively observed and characterized. This peculiar magnetic configuration appears only in films with a thickness above a critical value ($d_{cr}$), which is strongly determined by the sputtering conditions (i.e. deposition rate, temperature, magnetic field). So far, $d_{cr}$ has usually been presented as the boundary between the homogeneous (H) and stripe-domains (SD) regime, respectively below and above $d_{cr}$. In this work we study the transition from the H to the SD regime in thin films and microstructured bridges of Py with different thicknesses. We find the…