Matter-wave 2D solitons in crossed linear and nonlinear optical lattices

It is demonstrated the existence of multidimensional matter-wave solitons in a crossed optical lattice (OL) with linear OL in the $x-$direction and nonlinear OL (NOL) in the $y-$direction, where the NOL can be generated by a periodic spatial modulation of the scattering length using an optically induced Feshbach resonance. In particular, we show that such crossed linear and nonlinear OL allows to stabilize two-dimensional (2D) solitons against decay or collapse for both attractive and repulsive interactions. The solutions for the soliton stability are investigated analytically, by using a multi-Gaussian variational approach (VA), with the Vakhitov-Kolokolov (VK) necessary criterion for stability; and numerically, by using the relaxation method and direct numerical time integrations of the Gross-Pitaevskii equation (GPE). Very good agreement of the results corresponding to both treatments is observed.Comment: 8 pages (two-column format), with 16 eps-files of 4 figure

Developing personas and proto personas to enhance the art museum visitor experience

This paper aims to study and think about the use of personas and proto personas on the art museum visitors experience. Its object of study is the educational services of art museums focusing on children and young people up to the age of 18. This is a hybrid study - conceptual and empirical – and exploratory study. It was conducted through a qualitative methodology, constructivist paradigm and design approach. It relies on critical and creative thinking, as well on data collection. Using a total of 36 interviews to teachers/educators and children guardians, divided into 2 distinct phases, and a total of 3 pre-test interviews. This paper allowed to draw five conclusions. First, building personas enables the art museum to understand its audience. Visitor’s needs and objectives can be assessed in a more direct and efficient way by adapting designing strategies. Second, they are the basis for redesigning: the museum space, the visitor's journey and the visitor's experience. Third, personas allow to simulate a visitor model with differentiating profiles. Fourth, proto personas are created through brainstorming about the visitors, allowing to generate tools to start the early planning with a lower budget. Significant costs may be reduced and changes to management practices applied. Fifth, providing insights for the construction of a space for creative expression and nonformal education based on the visual arts aimed at children and young people up to the age of 18. This paper expands the investigation of application of the construction of personas and proto personas in the management of educational services in art museums. The value of this study lies in exploration of the construction of personas and in a learning context Do - Feel - Learn instead of the traditional sequence Learn - Feel - Do.info:eu-repo/semantics/publishedVersio

Quantum chaos in nanoelectromechanical systems

We present a theoretical study of the electron-phonon coupling in suspended nanoelectromechanical systems (NEMS) and investigate the resulting quantum chaotic behavior. The phonons are associated with the vibrational modes of a suspended rectangular dielectric plate, with free or clamped boundary conditions, whereas the electrons are confined to a large quantum dot (QD) on the plate's surface. The deformation potential and piezoelectric interactions are considered. By performing standard energy-level statistics we demonstrate that the spectral fluctuations exhibit the same distributions as those of the Gaussian Orthogonal Ensemble (GOE) or the Gaussian Unitary Ensemble (GUE), therefore evidencing the emergence of quantum chaos. That is verified for a large range of material and geometry parameters. In particular, the GUE statistics occurs only in the case of a circular QD. It represents an anomalous phenomenon, previously reported for just a small number of systems, since the problem is time-reversal invariant. The obtained results are explained through a detailed analysis of the Hamiltonian matrix structure.Comment: 14 pages, two column

Quantum Dynamics in a Time-dependent Hard-Wall Spherical Trap

Exact solution of the Schr\"{o}dinger equation is given for a particle inside a hard sphere whose wall is moving with a constant velocity. Numerical computations are presented for both contracting and expanding spheres. The propagator is constructed and compared with the propagator of a particle in an infinite square well with one wall in uniform motion.Comment: 6 pages, 4 figures, Accepted by Europhys. Let

Critical fluctuations and random-anisotropy glass transition in nematic elastomers

We carry out a detailed deuterium NMR study of local nematic ordering in polydomain nematic elastomers. This system has a close analogy to the random-anisotropy spin glass. We find that, in spite of the quadrupolar nematic symmetry in 3-dimensions requiring a first-order transition, the order parameter in the quenched ``nematic glass'' emerges via a continuous phase transition. In addition, by a careful analysis of the NMR line shape, we deduce that the local director fluctuations grow in a critical manner around the transition point. This could be the experimental evidence for the Aizenman-Wehr theorem about the quenched impurities changing the order of discontinuous transition

Are the clinical features of leprosy and American tegumentary leishmaniasis worse in patients with both diseases?

This cross-sectional population-based study compared clinical features of leprosy and American tegumentary leishmaniasis (ATL) in patients diagnosed with both diseases (n=414) and in those diagnosed with only leprosy (n=27,790) or only ATL (n=24,357) in Mato Grosso State, which is a hyperendemic area for both diseases in Midwest Brazil. All new cases of leprosy and ATL reported in the area from 2008 to 2017 were included. Patients diagnosed with both diseases were identified by a probabilistic linkage procedure applied to leprosy and ATL databases of the national reporting system. The distribution of the frequency of clinical features between groups was compared by the chi-square test, followed by a multivariate logistic regression. Patients diagnosed with both leprosy and ATL presented higher odds of having nerve damage (OR: 1.34; 95% CI: 1.09-1.66) and leprosy reactions (OR: 1.35; 95% CI: 1.04-1.76) compared to patients diagnosed only with leprosy. Mucocutaneous leishmaniasis (OR: 2.29; 95% CI: 1.74-3.00) was more frequent among patients with both diagnoses when compared to patients who only had ATL. In conclusion, patients diagnosed with both leprosy and ATL present more severe clinical features of such diseases. Our data can be useful for designing health policies aimed at timely and integrated management of leprosy and ATL in co-endemic areas