Una descoberta de la UAB ens apropa al somni de la invisibilitat

Un grup d'investigadors del departament de Física de la UAB ha aconseguit dissenyar un dispositiu que fa invisibles els objectes a un determinat tipus de llum, les ones electromagnètiques de molt baixa freqüència, tot fent que el camp magnètic sigui nul al seu interior, i deixant-lo intacte a l'exterior. D'aquesta manera, el dispositiu actua, de moment de manera teòrica, com una capa d'invisibilitat que fa l'objecte completament indetectable a aquestes ones.Un grupo de investigadores del departamento de Física de la UAB ha conseguido diseñar un dispositivo que hace invisibles los objetos a un determinado tipo de luz, las ondas electromagnéticas de muy baja frecuencia, que provocan que el campo magnético en su interior sea nulo, dejándolo intacto en el exterior. De esta manera, el dispositivo actúa, de momento de manera teórica, como una capa de invisibilidad que hace al objeto completamente indetectable a estas ondas.A group of researchers from the Department of Physics at UAB have designed a device which makes objects invisible under certain light - very low frequency electromagnetic waves - by making the interior magnetic field zero but not altering the exterior field. The device, which up to date has only been studied in theoretical works, acts as an invisibility cloak, making the object completely undetectable to these waves

Self-fields in thin superconducting tapes: implications to the thickness effect in coated conductors

Most applications of superconductors, such as power transmission lines, motors, generators, and transformers, require long cables through which large currents circulate. Impressive progress has recently been achieved in the current-carrying capability in conductors based on high-temperature superconductors. Coated conductors are likely the best examples, consisting of very good quality thin layers of YBCO superconductor grown on top of a metallic tape with some intermediate layers. However, there is an important problem for achieving large currents: a large decrease in transport critical-current density Jc when increasing film thickness has been observed in coated conductors made by all available techniques. Here, we theoretically explain the nature and the ubiquitous presence of this so-called thickness effect by analyzing the self-field created by the transport currents in the superconductor, assuming a realistic field-dependent Jc. This knowledge can help finding new ways to improve transport current in thick superconducting films.Comment: 7 pages, 3 figure

Controlling vortex chirality and polarity by geometry in magnetic nanodots

The independent control of both vortex chirality and polarity is a significant challenge in magnetic devices based on nano-sized magnetic vortex structures. By micromagnetic simulations here, we show that in soft ferromagnetic nanodots with an adequate modulated thickness, the desired combination of chirality and polarity can be achieved just by changing the direction of the in-plane applied magnetic field. Despite the complex behavior, the vortex chirality and polarity control can be summarized in two simple rules that can thus become a useful tool for designing magnetic devices

Imprinting skyrmions in thin films by ferromagnetic and superconducting templates

Magnetic skyrmions are promising candidates as information carriers in a new generation of memories. Here, we study the physical conditions for nucleating and stabilizing skyrmions by using local magnetic fields. We theoretically demonstrate how skyrmions can be imprinted in ultrathin ferromagnetic films, either individually and also in large numbers by bringing a magnetic nanostructured template close to the film. In this latter case, two kinds of templates, allowed by present-day nanotechnologies, are proposed: arrays of ferromagnetic nanorods or superconducting vortices

Potential benefits of a cognitive training program in MCI

Producción CientíficaBackground - Dementia is a disease that is constantly evolving in older people. Its diverse symptoms appear with varying degrees of severity affecting the daily life of those who suffer from it. The rate in which dementia progresses depends on different aspects of the treatment, chosen to try to control and slow down the development of the illness. Objective: The aim of this study is to assess the effectiveness of cognitive training through a Brain Computer Interface (BCI) and the NeuronUp platform in two age groups whose MMSE is between 18-23 MCI (mild dementia). Method: 32 subjects took part in the study. There were 22 subjects in Group 1 (61-69 years of age) and 10 subjects in Group 2 (70-81 years of age). The criteria for the selection of the groups was to identify the age range with greater improvements due to the training. In order to estimate neuropsychological performance, the subjects were evaluated with the Luria-DNA neuropsychological battery before and after training. This design enables us to evaluate five cognitive areas: visuospatial, spoken language, memory, intellectual processes and attention. Results: Showed that after the training, Group 1 obtained significant improvements in almost all the variables measured when compared with Group 2. This reveals a significant increase in cognitive ability, which degree of enhancement is probably associated with age. Conclusion: All people with mild dementia may delay cognitive impairment with a suitable cognitive training program.This research project was supported in part by “Ministerio de Economía y Competitividad” and FEDER under project TEC2014-53196-R, by ‘European Commission’ (POCTEP 0378_AD_EEGWA_2_P), and by ‘Consejería de Educación de la Junta de Castilla y León’ (VA037U16). J. Gomez-Pilar was in receipt of a grant from University of Valladolid. We thank the managers for their support in carrying out this study, and the people for accepting to participate in this research