Cat states in a driven superfluid: role of signal shape and switching protocol

We investigate the behavior of a one-dimensional Bose-Hubbard model whose kinetic energy is made to oscillate with zero time-average. The effective dynamics is governed by an atypical many-body Hamiltonian where only even-order hopping processes are allowed. At a critical value of the driving, the system passes from a Mott insulator to a superfluid formed by a cat-like superposition of two quasi-condensates with opposite non-zero momenta. We analyze the robustness of this unconventional ground state against variations of a number of system parameters. In particular we study the effect of the waveform and the switching protocol of the driving signal. Knowledge of the sensitivity of the system to these parameter variations allows us to gauge the robustness of the exotic physical behavior.Comment: 9 pages, 5 figure

A proposal of collaborative work in groups made up by students of the Faculty of the University of Castilla - La Mancha and the Pontifical Catholic University of Chile : A proposal using collaborative publishing tools.

De la experiencia del trabajo con herramientas de publicación colaborativas - wikis - de uno de los autores en la Pontificia Universidad Católica de Chile, nace el planteamiento de actividades en las que los alumnos de la Facultad de Educación de esta Universidad trabajen de manera colaborativa con alumnos de las Facultades de Educación de la Universidad de Castilla-La Mancha en el ámbito de la Didáctica de las Ciencias Experimentales. El hecho de trabajar en la misma área de conocimiento, desde una perspectiva diferente, amplía la capacidad de los futuros maestros para trabajar en contextos internacionales. Utilizar wikis en la Educación Superior como instrumento de trabajo colaborativo permite además trabajar competencias transversales como la multiculturalidad, el uso de las tecnologías de la información y la comunicación, las habilidades interpersonales, el trabajo en equipo y la eliminación de barreras espacio-temporales. El trabajo colaborativo en contextos internacionales permite a los alumnos trabajar sobre la adaptación de los contenidos de la Didáctica de las Ciencias Experimentales al aula, contextualizándola en otro sistema educativo diferente y no limitándose a la legislación vigente en España y en Castilla-La Mancha. Por otro lado, en la Didáctica de las Ciencias Experimentales, los ecosistemas constituyen un interesante recurso de trabajo, vertebrador que relaciona las diferentes disciplinas. Los trabajos colaborativos centrados en ecosistemas de ambos países suponen trasladar aquellos conocimientos relacionados con procesos observados en ecosistemas cercanos a otros estudiantes que no los conocen desde su experiencia directa. La importancia de estos aspectos en la formación de un futuro maestro es especialmente interesante actualmente cuando la capacidad de ejercer la profesión docente en el extranjero puede suponer una interesante salida laboral.Based on the work of one of the authors in the Pontifical Catholic University of Chile with collaborative publishing tools – wikis – there is a proposal for activities in which students of both universities, Castilla-La Mancha and Pontifical Catholic of Chile, can work collaboratively in the area of Didactics of Experimental Sciences. The fact of working in the same knowledge area, but from a different perspective, enhances the ability of the future teachers to work in international contexts. Using wikis in Universities as a tool for collaborative publishing, allows to develop transversal competences like multiculturality, the use of information and communication technologies (ICT), interpersonal abilities, the group work and the removal of time and space barriers. Collaborative work in an international context allow students to work on the adaptation of the Didactics of Experimental Sciences contents to schools, making them sensitive to another educative system and not only applying these contents to the current legislation in Spain and in Castilla-La Mancha. Besides, ecosystems are a powerful tool that vertebrate the relationship between the Didactics of Experimental Sciences and other disciplines. Collaborative works focused on Spanish and Chilean ecosystems implies the transfer of knowledge related to processes observed in these nearby ecosystems to other students that don't know them from their direct experience. The importance of all these aspects in the education of future teachers is especially interesting nowadays, when the ability to work as a teacher in a foreign country may constitute a significant opportunit

Superfluidity from correlations in driven boson systems

We investigate theoretically the superfluidity of a one-dimensional boson system whose hopping energy is periodically modulated with a zero time average, which results in the suppression of first-order single-particle hopping processes. The dynamics of this flat band system is entirely driven by correlations and described by exotic Hamiltonian and current operators. We employ exact diagonalization and compare our results with those of the conventional, undriven Bose-Hubbard system. We focus on the two main manifestations of superfluidity, the Hess-Fairbank effect and the metastability of supercurrents, with explicit inclusion of an impurity when relevant. Among the novel superfluid features, we highlight the presence of a cat-like ground state, with branches that have opposite crystal momentum but carry the same flux-dependent current, and the essential role of the interference between the collective components of the ground-state wave function. Calculation of the dynamic form factor reveals the presence of an acoustic mode that guarantees superfluidity in the thermodynamic limit.Comment: 14 pages, 9 figure

Impact of short-term extreme temperature events on physiological performance of Salicornia ramosissima J. Woods under optimal and sub-optimal saline conditions

Increasing extreme temperature climatic events could exert an important effect on plant photosynthetic performance, which could be modulated by the co-occurrence with other environmental factors, such as salinity, in estuarine ecosystems. Therefore, a mesocosm experiment was designed to assess the impact of temperature events for three days (13/5 °C, 25/13 °C and 40/28 °C) in combination with two NaCl concentrations (171 and 1050 mM NaCl) on the physiological performance of Salicornia ramosissima. Extreme temperature events had a negative impact on S. ramosissima photosynthetic efficiency, this effect being more marked with cold wave at both salinities, compared with heat wave, even in presence of NaCl excess. This differential thermotolerance in the photosynthetic apparatus was ascribed to the greater integrity and functioning of its photosynthetic pathway at high temperature, as indicated by constant gs, Vc,max values at optimal salinity and the higher values of those parameters and gm recorded in combination with NaCl excess. Moreover, S. ramosissima was able to upregulate the energy sink capacity of its photochemical apparatus at elevated temperature and salinity by a greater energy excess dissipation capacity. This could have contributed to reducing the risk of oxidative stress, along with the recorded higher capacity for antioxidant enzyme activity modulation under these conditions.España, MINECO Project CGL2016– 75550-

Potential welfare issues of the Siamese fighting fish (Betta splendens) at the retailer and in the hobbyist aquarium

Betta splendens is an extremely popular ornamental fish among hobby aquarists. It has an interesting behavioral repertoire, particularly where male aggression and territoriality are concerned. The lack of scientific studies investigating optimal housing conditions in combination with the wide variety of commercially available husbandry products, raises questions about the welfare status of these fish in captivity. In this article, an overview of the available literature on the biology of the betta and general considerations of ornamental fish keeping is given, and environment- and animal-related factors with potential impact on the welfare of Betta splendens are examined. Although more research using biological and physiological indicators is needed, the following factors constituting welfare problems have been identified: an aquarium of limited dimensions, prevalence of Mycobacterium spp. infection, aggression to and from conspecifics or other species in the same aquarium and the limited ability to escape, potential for stress due to prolonged visual contact between males in shops and during shows, and the lack of environmental enrichment in the form of sheltering vegetation

Specification of Adleman’s Restricted Model Using an Automated Reasoning System: Verification of Lipton’s Experiment

The aim ofthis paper is to develop an executable prototype ofan unconventional model ofcomputation. Using the PVS verification system (an interactive environment for writing formal specifications and checking formal proofs), we formalize the restricted model, based on DNA, due to L. Adleman. Also, we design a formal molecular program in this model that solves SAT following Lipton’s ideas.We prove using PVS the soundness and completeness ofthis molecular program. This work is intended to give an approach to the opportunities offered by mechanized analysis ofuncon ventional model ofcomputation in general. This approach opens up new possibilities ofv erifying molecular experiments before implementing them in a laboratory.Ministerio de Educación y Cultura TIC2000-1368-C03-02Ministerio de Educación y Cultura PB96-134