Controllable soliton emission from a Bose-Einstein condensate

We demonstrate, through numerical simulations, the controllable emission of matter-wave bursts from a Bose-Einstein Condensate in a shallow optical dipole trap. The process is triggered by spatial variations of the scattering length along the trapping axis. In our approach, the outcoupling mechanism are atom-atom interactions and thus, the trap remains unaltered. Once emitted, the matter wave forms a robust soliton. We calculate analytically the parameters for the experimental implementation of this atomic soliton machine gun.Comment: 4 pages, 5 figure

Sistema de control embebido para convertidor DC/DC de alta elevación

Este trabajo aborda el tema de los convertidores corriente directa/corriente directa (DC/DC), cuyo desarrollo se presenta como un sistema embebido de aplicación automotriz, que incluye las explicaciones del circuito electrónico, el programa del sistema, la ley de control del convertidor y el proceso que asegura la calidad del sistema. El convertidor DC/DC atiende a la problemática de elevar el voltaje suministrado por una batería de plomo de 12V a un voltaje de corriente continua de hasta 400 V con una potencia máxima de 200W y eficiencia superior al 90%. Típicamente los convertidores de voltaje tienen una ganancia que oscila entre 10 y 15 unidades, por lo que una ganancia superior a las 30 unidades se considera alta ganancia. Para cubrir el requisito de alta ganancia el presente proyecto propone la utilización de un convertidor cuya topología se considera novedosa respecto a circuitos tradicionales como el BOOST o el Flyback. Lo novedoso del funcionamiento del convertidor DC/DC radica en su configuración capaz de cargar dos capacitores en paralelo y descargarlos en serie a la vez que combina la topología tradicional del convertidor Flyback. Adicionalmente, se incorpora como elemento de conmutación un MOSFET de SiC, cuya capacidad de operación en temperaturas superiores a 150 ° C lo convierte en un elemento ideal para aplicaciones automotrices.Consejo Nacional de Ciencia y Tecnologí

Sex differences across teacher’s motivation, teaching satisfaction, loneliness and affects during COVID-19

Motivation, teaching satisfaction, loneliness and affects are significant variables concerning the quality of teaching performance. Nevertheless, the presence of the homebased teaching during COVID- 19 could have influenced these variables. As such, the goals of this research were to examine whether there are sex differences in teacher’s motivation, teaching satisfaction, loneliness and affects; and if there is any association of age on teacher motivation, teaching satisfaction, loneliness and affects. A sample of 315 teachers (Mage=41.95; SD=10.18) participated in the study and fulfilled a series of self-report questionnaires during COVID-19 homebased teaching. Results revealed significant sex differences in identified regulation, loneliness, and balance of negative affects. In particular, female teachers reported significantly higher scores in identified regulation and balance of negative affects and men reported higher scores in loneliness. In conclusion, it should be considered to create interventions to help teachers to reduce the negative consequences of loneliness and negative affects on teaching performance and to enhance motivational profiles, especially among men teachers.La motivación, la satisfacción docente, la soledad y los estados afectivos son variables significativas en el rendimiento docente. No obstante, la presencia de la docencia en casa durante la COVID-19 puede haber influido en estas variables. Por ello, los objetivos de esta investigación fueron examinar si existen diferencias de sexo en la motivación del docente, la satisfacción docente, la soledad y los estados afectivos; y si existe alguna asociación entre la edad y la motivación del docente, la satisfacción docente, la soledad y los estados afectivos. Una muestra de 315 docentes (Mage=41.95; DT=10.18) participó en el estudio y cumplimentó una serie de cuestionarios de autoinforme durante el periodo de COVID-19 de docencia en casa. Los resultados revelaron que existen diferencias de sexo en la regulación identificada, la soledad y el equilibrio de los afectos negativos. En particular, las docentes obtuvieron puntuaciones significativamente más altas en regulación identificada y equilibrio de los afectos negativos y los docentes reportaron puntuaciones más altas en la variable soledad. En conclusión, se debe considerar crear intervenciones para ayudar a los docentes a reducir las consecuencias negativas de la soledad y los estados afectivos negativos sobre el rendimiento docente y mejorar los perfiles motivacionales, especialmente entre los docentes hombres

Dynamics of Elastic Excitable Media

The Burridge-Knopoff model of earthquake faults with viscous friction is equivalent to a van der Pol-FitzHugh-Nagumo model for excitable media with elastic coupling. The lubricated creep-slip friction law we use in the Burridge-Knopoff model describes the frictional sliding dynamics of a range of real materials. Low-dimensional structures including synchronized oscillations and propagating fronts are dominant, in agreement with the results of laboratory friction experiments. Here we explore the dynamics of fronts in elastic excitable media.Comment: Int. J. Bifurcation and Chaos, to appear (1999

Turning light into a liquid via atomic coherence

We study a four level atomic system with electromagnetically induced transparency with giant $\chi^{(3)}$ and $\chi^{(5)}$ susceptibilities of opposite signs. This system would allow to obtain multidimensional solitons and light condensates with surface tension properties analogous to those of usual liquids

Symbiotic Solitons in Heteronuclear Multicomponent Bose-Einstein condensates

We show that bright solitons exist in quasi-one dimensional heteronuclear multicomponent Bose-Einstein condensates with repulsive self-interaction and attractive inter-species interaction. They are remarkably robust to perturbations of initial data and collisions and can be generated by the mechanism of modulational instability. Some possibilities for control and the behavior of the system in three dimensions are also discussed

Web attack detection using ID3

Decision tree learning algorithms have been successfully used in knowledge discovery. They use induction in order to provide an appropriate classification of objects in terms of their attributes, inferring decision tree rules. This paper reports on the use of ID3 to Web attack detection. Even though simple, ID3 is sufficient to put apart a number of Web attacks, including a large proportion of their variants. It also surpasses existing methods: it portrays a higher true-positive detection rate and a lower false-positive one. The ID3 output classification rules that are easy to read and so computer officers are more likely to grasp the root of an attack, as well as extending the capabilities of the classifier.Applications in Artificial Intelligence - ApplicationsRed de Universidades con Carreras en Informática (RedUNCI

Anomalous rotational properties of Bose-Einstein condensates in asymmetric traps

We study the rotational properties of a Bose-Einstein condensate confined in a rotating harmonic trap for different trap anisotropies. Using simple arguments, we derive expressions for the velocity field of the quantum fluid for condensates with or without vortices. While the condensed gas describes open spiraling trajectories, on the frame of reference of the rotating trap the motion of the fluid is against the trap rotation. We also find explicit formulae for the angular momentum and a linear and Thomas-Fermi solutions for the state without vortices. In these two limits we also find an analytic relation between the shape of the cloud and the rotation speed. The predictions are supported by numerical simulations of the mean field Gross-Pitaevskii model.Comment: 4 RevTeX pages, 2 EPS figures; typos fixed, reference adde

Vinyl sulfonyl chemistry-driven unidirectional transport of a macrocycle through a [2]rotaxane

This work has been financially supported by FEDER(EDRF)/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades (P18-FR-2877), grant PID2020-112906GA-I00 funded by MCIN/AIE (/10.13039/501100011033) and Ministerio de Economia y Competitividad (MINECO, Spain) (CTQ2014-55474-C2-2-R and CTQ2017-86125P, co-financed by FEDER funds). Funding for open access APCs provided by Universidad de Granada through a Paid by Read & Publish agreement with RSC.By applying a combination of the coupling-and-decoupling (CAD) chemistry of the vinyl sulfonate group with the click thia-Michael addition to the vinyl sulfone group (MAVS) we performed the irreversible unidirectional transportation of the ring through the linear component in a [2]rotaxane by a chemically and pH-driven flashing energy ratchet mechanism. The design is based on a monostoppered thread precursor bearing a sulfonate stopper, a vinyl sulfone group on the unstoppered end and a dibenzylammonium unit as recognition site for the dibenzo-24-crown-8 macrocycle. First, the ring enters from the vinyl sulfone side and the rotaxane is capped through a thia-Michael addition reaction. Then, the cleavage of the sulfonate group of the opposite stopper using MgBr2 as chemical stimulus and subsequent addition of base (Et3N) promoted the controlled and directional release of the macrocycle into the bulk under mild conditions. The efficiency of the system allowed the in situ operation as demonstrated by NMR and HRMS techniques.FEDER(EDRF)/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades - MCIN/AIE P18-FR-2877Ministerio de Economia y Competitividad (MINECO, Spain) (FEDER funds) CTQ2014-55474-C2-2-R; CTQ2017-86125PUniversidad de GranadaRSCMCIN/AIE PID2020-112906GA-I0