Magnetization plateaux in the classical Shastry-Sutherland lattice

We investigated the classical Shastry-Sutherland lattice under an external magnetic field in order to understand the recently discovered magnetization plateaux in the rare-earth tetraborides compounds RB$_4$. A detailed study of the role of thermal fluctuations was carried out by mean of classical spin waves theory and Monte-Carlo simulations. Magnetization quasi-plateaux were observed at 1/3 of the saturation magnetization at non zero temperature. We showed that the existence of these quasi-plateaux is due to an entropic selection of a particular collinear state. We also obtained a phase diagram that shows the domains of existence of different spin configurations in the magnetic field versus temperature plane.Comment: 4 pages, proceedings of HFM200

Mechanism of Glucose Isomerization Using a Solid Lewis Acid Catalyst in Water

^1H and ^(13)C NMR spectroscopy on isotopically labeled glucose reveals that in the presence of tin-containing zeolite Sn-Beta, the isomerization reaction of glucose in water proceeds by way of an intramolecular hydride shift (see scheme) rather than proton transfer. This is the first mechanistic demonstration of Sn-Beta acting as a Lewis acid in a purely aqueous environment

Influence of lattice distortions in classical spin systems

We investigate a simple model of a frustrated classical spin chain coupled to adiabatic phonons under an external magnetic field. A thorough study of the magnetization properties is carried out both numerically and analytically. We show that already a moderate coupling with the lattice can stabilize a plateau at 1/3 of the saturation and discuss the deformation of the underlying lattice in this phase. We also study the transition to saturation where either a first or second order transition can occur, depending on the couplings strength.Comment: Submitted to Phys. Rev.

Uncertainty in estimating time-to-passage revealed by reaction times

Fundação para a Ciência e Tecnologia (FCT

Open Organization Networks: Combining closure and openness in the social world of an European Buddhist Monastery

We present a social network study of a southern European Buddhist monastery that aimed at taking Buddhism from the monastery to society. It is an interesting experiment of fusion between Buddhism and the west and of its adaptation to modern times and new lands. We adopt the relational perspective to understand its adaptation process, the organizational forms used, its dynamics, its life, and its relations with the surrounding society. Our study shows that the use of social relations has been essential for the success of the organization and its project. The social system they created is rich, complex, and has a great capacity for offering services and taking action. It is an interesting case of relation between meaning and form. The meaning, the project, generates a specific organizational form (networks) to guarantee the closure necessary for certain functions and the necessary openness for its project towards society

The time to passage of biological and complex motion

A significant part of human interactions occur with other human beings and not only with inanimate objects. It is important in everyday tasks to estimate the time it takes other people to reach (time to contact) or pass us (time to passage). Surprisingly, little is known about judging time to contact or time to passage of biological or other complex motions. In two experiments, rigid and non-rigid (biological, inverted, scrambled, and complex non-biological) motion conditions were compared in a time-to-passage judgment task. Subjects could judge time to passage of point-light-walker displays. However, due to relative and opponent movements of body parts, all articulated patterns conveyed a noisier looming pattern. Non-rigid stimuli were judged as passing sooner than rigid stimuli but reflected more uncertainty in the judgments as revealed by precision judgments and required longer reaction times. Our findings suggested that perceptual judgments for complex motion, including biological patterns, are built on top of the same processing channels that are involved on rigid motion perception. The complexity of the motion pattern (rigid vs. non-rigid) plays a more determinant role than the "biologicity" of the stimulus (biological vs. non-biological), at least concerning time-to-passage judgments

The benefit of multisensory integration with biological motion signals

Assessing intentions, direction, and velocity of others is necessary for most daily tasks, and such information is often made available by both visual and auditory motion cues. Therefore, it is not surprising our great ability to perceive human motion. Here, we explore the multisensory integration of cues of biological motion walking speed. After testing for audiovisual asynchronies (visual signals led auditory ones by 30ms in simultaneity temporal windows of 76.4ms), in the main experiment, visual, auditory, and bimodal stimuli were compared to a standard audiovisual walker in a velocity discrimination task. Results in variance reduction conformed to optimal integration of congruent bimodal stimuli across all subjects. Interestingly, the perceptual judgments were still close to optimal for stimuli at the smallest level of incongruence. Comparison of slopes allows us to estimate an integration window of about 60ms, which is smaller than that reported in audiovisual speech.This work was partly funded by the Portuguese Foundation for Science and Technology (SFRH/BD/36345/2007, PTDC/SAU-BEB/68455/2006, SFRH/BSAB/974/2009) and the Portugal-Spain Actions PT2009-0186 from the Spanish Government and E-134/10 from the Portuguese Conselho de Reitores das Universidades Portuguesas

Redefining the territory of school: educational spaces for social transformation

The study is focused on a project of a school and community transformation process developed in a rural school that review the curricular practices in order to link to territory from an intercultural and inclusive framework. The method is a case study. A Learning Service project is planned and implemented in order to link the school curriculum with the needs of the territory. The aim is to describe and analyse how the processes of participation of the educational community and the democratic negotiation of the school curriculum have enhanced the cohesion of the educational community around a common goal in a territory in tension. The qualitative tools to collect and produce data have been participant observation, interviews and focus groups. The results show that the practice of the ApS has been an opportunity for students to learn curricular contents and develop competences connected to their own context. The curricular practice makes to think about educational spaces critically, enhancing the students’ empowerment in defense of the right to a dignified school of quality. The permeability of the school and its positioning as an agent of social change appear as key factors in the development and management of a democratic school.El estudio que se presenta se enmarca en un proyecto de transformación escolar y comunitaria desarrollado en una escuela rural, que reformula sus prácticas curriculares para vincularse a su territorio desde un modelo educativo intercultural e inclusivo. Metodológicamente se trata de un estudio de caso. En él se planifica e implementa una práctica educativa de aprendizaje de servicio (ApS) en la que se vincula el currículum de la escuela y las necesidades del territorio. El objetivo es describir y analizar de qué manera los procesos de participación de la comunidad educativa y la negociación democrática del currículum escolar han favorecido la cohesión de la comunidad educativa mediante la vertebración de un proyecto común en un territorio en tensión. Los instrumentos de recogida y producción de datos han sido la observación participante, entrevistas y grupos de discusión. Los resultados muestran que la práctica del ApS supuso una oportunidad para el aprendizaje de contenidos curriculares y el desarrollo de competencias por parte del alumnado a partir de su entorno más inmediato. La práctica curricular desarrollada hace repensar los espacios educativos, permitiendo el empoderamiento del alumnado en su defensa del derecho a una escuela digna y de calidad. La permeabilidad de la escuela y su posicionamiento como agente de cambio social, aparecen como factores clave en el desarrollo y gestión de una escuela democrática.Ministerio de Economía y Competitividad EDU2015-68004-RFondo Europeo de Desarrollo Regional EDU2015-68004-RGobierno Autónomo AICO/2018/06

The time to passage of biological and complex motion

A significant part of human interactions occur with other human beings and not only with inanimate objects. It is important in everyday tasks to estimate the time it takes other people to reach (time to contact) or pass us (time to passage). Surprisingly, little is known about judging time to contact or time to passage of biological or other complex motions. In two experiments, rigid and non-rigid (biological, inverted, scrambled, and complex non-biological) motion conditions were compared in a time-to-passage judgment task. Subjects could judge time to passage of point-light-walker displays. However, due to relative and opponent movements of body parts, all articulated patterns conveyed a noisier looming pattern. Non-rigid stimuli were judged as passing sooner than rigid stimuli but reflected more uncertainty in the judgments as revealed by precision judgments and required longer reaction times. Our findings suggested that perceptual judgments for complex motion, including biological patterns, are built on top of the same processing channels that are involved on rigid motion perception. The complexity of the motion pattern (rigid vs. non-rigid) plays a more determinant role than the “biologicity” of the stimulus (biological vs. non-biological), at least concerning time-to-passage judgments.Luso-Spanish Integrated Action funded by the Spanish and Portuguese governmentsFundação para a Ciência e a Tecnologia (FCT

Assessment of the relationship between physical performance and percentage change-of-direction deficit in highly trained female football players

Purpose: Different studies indicate that female players in team sports, such as soccer, tend to have a lower change of direction deficit (CODD) than their male counterparts and that players who performed better in linear and curved sprints tended to have a worse CODD, suggesting that maximum speed does not equate to a faster change of direction (COD). This study assessed how performance variables related to speed and jumping influence the variability of %CODD among adult highly trained female soccer players. Methods: Fifty-two highly trained female soccer players (age: 23.1 ± 3.25 years; height: 163.6 ± 5.49 cm; weight: 59.7 ± 5.71 kg) participated in this study and performed 180COD, 40-m sprint, countermovement jump (CMJ), and standing broad jump (SBJ) tests. Results: Significant correlations were found between 180CODL, %CODDR, %CODDL, and between-limbs SBJ asymmetry (r = 0.28 to 0.74). A very large correlation existed between %CODDR and %CODDL (r = 0.91). Regression analyses indicated a strong inverse relationship between the 10-m sprint time and %CODDR and %CODDL. No predictive models were found for 180COD in either limb. Differences in performance variables such as 180CODR, 180CODL, and asymmetry %CODD were significant between the high and low %CODD groups, with moderate to large effect sizes. Conclusions: The present study suggests that specific physical performance variables, particularly acceleration and unilateral horizontal jumping, are vital to improving COD in highly trained female soccer players, highlighting the need for specific training interventions