Critical properties and Bose Einstein Condensation in dimer spin systems

We analyze the spin relaxation time $1/T_1$ for a system made of weakly coupled one dimensional ladders.This system allows to probe the dimensional crossover between a Luttinger liquid and a Bose-Einstein condensateof magnons. We obtain the temperature dependence of $1/T_1$ in the various dimensional regimes, and discuss the experimental consequences.Comment: 4 pages, RevTeX 4, 3 EPS figure

Pre-service Special and General Educators’ Perceptions of Bullying

Successful approaches for decreasing bullying among youth hinge on the competence of teachers, yet teachers’ perceptions of bullying often differ from those of students. This study used the Bullying Perceptions Scale—Revised to investigate perceptions of 221 pre-service teachers at a large university in the midwestern United States. Results suggested that pre-service teachers believe all topographies of bullying warrant intervention. Additionally, when asked to recall an episode of bullying, pre-service teachers typically recalled a scenario that involved verbal bullying (84.0%), occurred in the classroom (43.6%), in elementary (44.0%) or middle school (39.6%), when teachers were present (50.2%). The findings imply a need for increased focus on bully identification and prevention in the teacher preparation curriculum

Medidas experimentales de desplazamientos micrométricos basadas en vórtices ópticos

In this work, a system for measuring micrometer-displacements based on the characteristics of optical vortices is presented. In the proposal, a binary vortex-producing lens (BVPL) programmed to generate optimized optical vortices is transversally displaced from the optical axis, inducing perturbations on the optical characteristics of the vortices that are used as transduction parameters. Specifically, the method proposed theoretically by Anzolin et al. [18], which is based on the asymmetry of the intensity patterns of the off-axis optical vortices, is studied experimentally by using BVPLs. Experimental implementation is completely described and compared with theoretical results, likewise, metrological characteristics of the experimental metrological system are analyzed. Based on the results, we experimentally confirm the possibility of creating high sensitivity metrological systems by using optical vortices, opening the door for new vortex metrology techniques.En este trabajo, un sistema para medir desplazamientos micrométricos basados en las características de vórtices ópticos es presentado. En la propuesta, una lente productora de vórtices binaria (BVPL) programada para generar vórtices ópticos optimizados es desplazada transversalmente del eje óptico, induciendo perturbaciones en las características ópticas de los vórtices que son usadas como parámetros de transducción. Específicamente, el método propuesto por Anzolín et al [18], el cuál es basado en la asimetría de los patrones de intensidad de los vórtices ópticos fuera del eje, es estudiado experimentalmente usando BVPLs. Se describe completamente la implementación experimental y se compara con los resultados teóricos, así mismo, se analizan características metrológicas del sistema metrológico experimental. En base a los resultados, confirmamos experimentalmente la posibilidad de crear sistemas metrológicos de alta sensibilidad utilizando vórtices ópticos, abriendo la puerta para nuevas técnicas de metrología de vórtices.Centro de Investigaciones Óptica

Exact ground states for the four-electron problem in a Hubbard ladder

The exact ground state of four electrons in an arbitrary large two leg Hubbard ladder is deduced from nine analytic and explicit linear equations. The used procedure is described, and the properties of the ground state are analyzed. The method is based on the construction in r-space of the different type of orthogonal basis wave vectors which span the subspace of the Hilbert space containing the ground state. In order to do this, we start from the possible microconfigurations of the four particles within the system. These microconfigurations are then rotated, translated and spin-reversed in order to build up the basis vectors of the problem. A closed system of nine analytic linear equations is obtained whose secular equation, by its minimum energy solution, provides the ground state energy and the ground state wave function of the model.Comment: 10 pages, 7 figure

MosAIck: Staging Contemporary AI Performance - Connecting Live Coding, E-Textiles and Movement

This paper introduces our collective work “Patterns in Between Intelligences”, a performance piece that builds an artistic practice between live coding sounds and coding through dance, mediated and shaped through e-textile sensors. This creates a networked system of which both live coded processes and human bodies are part. The paper describes in detail the implementations of technology used in the prototype performance performed at No Bounds Festival in Sheffield UK, October 2022, as well as discussions and concerns the team had related to the use of AI technology on stage. The paper concludes with a narrative reflection on the Sheffield performance, and reflections on it

Are Debris Disks and Massive Planets Correlated?

Using data from the Spitzer Space Telescope Legacy Science Program ``Formation and Evolution of Planetary Systems'' (FEPS), we have searched for debris disks around 9 FGK stars (2-10 Gyr), known from radial velocity (RV) studies to have one or more massive planets. Only one of the sources, HD 38529, has excess emission above the stellar photosphere; at 70 micron the signal-to-noise ratio in the excess is 4.7 while at wavelengths < 30 micron there is no evidence of excess. The remaining sources show no excesses at any Spitzer wavelengths. Applying survival tests to the FEPS sample and the results for the FGK survey published in Bryden et al. (2006), we do not find a significant correlation between the frequency and properties of debris disks and the presence of close-in planets. We discuss possible reasons for the lack of a correlation.Comment: 24 pages, 3 figures. Accepted to Astrophysical Journa