Semiclassical Tunneling of Wavepackets with Real Trajectories

Semiclassical approximations for tunneling processes usually involve complex trajectories or complex times. In this paper we use a previously derived approximation involving only real trajectories propagating in real time to describe the scattering of a Gaussian wavepacket by a finite square potential barrier. We show that the approximation describes both tunneling and interferences very accurately in the limit of small Plank's constant. We use these results to estimate the tunneling time of the wavepacket and find that, for high energies, the barrier slows down the wavepacket but that it speeds it up at energies comparable to the barrier height.Comment: 23 pages, 7 figures Revised text and figure

Coherent State Path Integrals in the Weyl Representation

We construct a representation of the coherent state path integral using the Weyl symbol of the Hamiltonian operator. This representation is very different from the usual path integral forms suggested by Klauder and Skagerstan in \cite{Klau85}, which involve the normal or the antinormal ordering of the Hamiltonian. These different representations, although equivalent quantum mechanically, lead to different semiclassical limits. We show that the semiclassical limit of the coherent state propagator in Weyl representation is involves classical trajectories that are independent on the coherent states width. This propagator is also free from the phase corrections found in \cite{Bar01} for the two Klauder forms and provides an explicit connection between the Wigner and the Husimi representations of the evolution operator.Comment: 23 page

Geometric combinatorial algebras: cyclohedron and simplex

In this paper we report on results of our investigation into the algebraic structure supported by the combinatorial geometry of the cyclohedron. Our new graded algebra structures lie between two well known Hopf algebras: the Malvenuto-Reutenauer algebra of permutations and the Loday-Ronco algebra of binary trees. Connecting algebra maps arise from a new generalization of the Tonks projection from the permutohedron to the associahedron, which we discover via the viewpoint of the graph associahedra of Carr and Devadoss. At the same time that viewpoint allows exciting geometrical insights into the multiplicative structure of the algebras involved. Extending the Tonks projection also reveals a new graded algebra structure on the simplices. Finally this latter is extended to a new graded Hopf algebra (one-sided) with basis all the faces of the simplices.Comment: 23 figures, new expanded section about Hopf algebra of simplices, with journal correction

Predictors of shared book reading at home with preschoolers: Are there differences between Roma and non-Roma low-income families?

Previous research highlights several benefits of shared book reading (SBR) for child development, but less studies exist about its predictors (Yarosz & Barnett, 2001). Literature on home SBR in Portugal is scarce (Araújo & Costa, 2015; Peixoto et al., 2008), and studies on its predictors in families at socioeconomic risk or Roma families in this context are, respectively, reduced (Gamelas et al., 2003) or inexistent. This study aimed to investigate the predictors of the frequency of SBR in two ethnically diverse groups of families. Specifically, we studied the associations between child and family (mother) characteristics, parental aspirations, and parental involvement in preschool events and frequency of home SBR. Two hundred and six caregivers of Portuguese Roma ( n = 101) and non-Roma ( n = 105) low-income preschoolers (109 boys; M age = 5, SD age = 0.94) living in the Metropolitan areas of Lisbon and Oporto, Portugal, completed a survey, in face-to-face meetings. A multiple regression model, using AMOS (v. 25), showed that mothers’ educational level, educational aspirations for their child, and involvement in informal (but not formal) events in preschool were positively associated with frequency of SBR. Ethnicity did not moderate these associations. The overall similar pattern results for Roma and non-Roma low income families is an important finding, suggesting that these families may experience similar challenges in engaging in SBR with their preschool children and, therefore, may benefit from interventions with similar features.info:eu-repo/semantics/acceptedVersio

SIMBA: a web tool for managing bacterial genome assembly generated by Ion PGM sequencing technology

Background The evolution of Next-Generation Sequencing (NGS) has considerably reduced the cost per sequenced-base, allowing a significant rise of sequencing projects, mainly in prokaryotes. However, the range of available NGS platforms requires different strategies and software to correctly assemble genomes. Different strategies are necessary to properly complete an assembly project, in addition to the installation or modification of various software. This requires users to have significant expertise in these software and command line scripting experience on Unix platforms, besides possessing the basic expertise on methodologies and techniques for genome assembly. These difficulties often delay the complete genome assembly projects. Results In order to overcome this, we developed SIMBA (SImple Manager for Bacterial Assemblies), a freely available web tool that integrates several component tools for assembling and finishing bacterial genomes. SIMBA provides a friendly and intuitive user interface so bioinformaticians, even with low computational expertise, can work under a centralized administrative control system of assemblies managed by the assembly center head. SIMBA guides the users to execute assembly process through simple and interactive pages. SIMBA workflow was divided in three modules: (i) projects: allows a general vision of genome sequencing projects, in addition to data quality analysis and data format conversions; (ii) assemblies: allows de novo assemblies with the software Mira, Minia, Newbler and SPAdes, also assembly quality validations using QUAST software; and (iii) curation: presents methods to finishing assemblies through tools for scaffolding contigs and close gaps. We also presented a case study that validated the efficacy of SIMBA to manage bacterial assemblies projects sequenced using Ion Torrent PGM. Conclusion Besides to be a web tool for genome assembly, SIMBA is a complete genome assemblies project management system, which can be useful for managing of several projects in laboratories. SIMBA source code is available to download and install in local webservers at http://ufmg-simba.sourceforge.net

Equilibrium and Disorder-induced behavior in Quantum Light-Matter Systems

We analyze equilibrium properties of coupled-doped cavities described by the Jaynes-Cummings- Hubbard Hamiltonian. In particular, we characterize the entanglement of the system in relation to the insulating-superfluid phase transition. We point out the existence of a crossover inside the superfluid phase of the system when the excitations change from polaritonic to purely photonic. Using an ensemble statistical approach for small systems and stochastic-mean-field theory for large systems we analyze static disorder of the characteristic parameters of the system and explore the ground state induced statistics. We report on a variety of glassy phases deriving from the hybrid statistics of the system. On-site strong disorder induces insulating behavior through two different mechanisms. For disorder in the light-matter detuning, low energy cavities dominate the statistics allowing the excitations to localize and bunch in such cavities. In the case of disorder in the light- matter coupling, sites with strong coupling between light and matter become very significant, which enhances the Mott-like insulating behavior. Inter-site (hopping) disorder induces fluidity and the dominant sites are strongly coupled to each other.Comment: about 10 pages, 12 figure

Durability of concrete protected by an acrylic painting

The fast degradation of concrete is a problem that occurs in some structures. In order to have less degradation, the use of protection systems could be recommended. Acrylic paintings have properties that make possible its use as a protection material of concrete. In our study, one concrete that could be classified as a C33/43, was protected with two coats of an acrylic painting. The durability of the protected concrete was studied. Tests made were: capillarity absorption, oxygen permeability, sulphates attack and freeze-thaw. The results show in general, that the degradation of the protected concrete is lower than the degradation of non protected concrete. For the absorption of water by capillarity the non protected specimens absorbed about three times more water than the protected specimens. The oxygen permeability of the protected specimens was about half of that of the non protected specimens. The results of the tests did not show any increase on the resistance of the concrete to the sulphate attack by the use of an acrylic painting. The non protected specimens presented degradation on the freeze-thaw tests after the cycle number 220. The protected systems only presented degradation on the same tests after the cycle number 270.(undefined

Combinatorial Hopf algebras and Towers of Algebras

Bergeron and Li have introduced a set of axioms which guarantee that the Grothendieck groups of a tower of algebras $\bigoplus_{n\ge0}A_n$ can be endowed with the structure of graded dual Hopf algebras. Hivert and Nzeutzhap, and independently Lam and Shimozono constructed dual graded graphs from primitive elements in Hopf algebras. In this paper we apply the composition of these constructions to towers of algebras. We show that if a tower $\bigoplus_{n\ge0}A_n$ gives rise to graded dual Hopf algebras then we must have $\dim(A_n)=r^nn!$ where $r = \dim(A_1)$.Comment: 7 page

Projeto Kit@: Formação em literacia mediática para educadores de infância na Europa

Esta comunicação resulta do trabalho realizado no âmbito do Projeto Erasmus + Kit@ - Formação profissional para o desenvolvimento da literacia mediática em profissionais de educação de infância e instituições comparáveis da Europa (2017-2020) - 2017-1-DE02-KA202-004186. Contou com a participação de instituições da Alemanha, Bulgária, Eslováquia, Grécia e Portugal. Um dos objetivos do Projeto visava a criação de soluções inovadoras para o desenvolvimento de competências pedagógicas de educação para os media. Também pretendeu promover a literacia mediática e o desenvolvimento de competências digitais em jardim de infância, utilizando Tecnologias de Informação e Comunicação. Com base na análise do estado de arte sobre a educação para os media, em idade pré-escolar, foram criados ambientes virtuais de aprendizagem (em formato e-learning) através do desenho de um portal online multilingue com: um curso de formação, um manual interativo e exemplos práticos, ofertas de aprendizagem baseadas na Web, um teste de avaliação de competências e um conjunto de aplicações úteis (ver https://kita-project.eu/). Os recursos produzidos foram avaliados (em 2020, em diversas zonas de Portugal Continental), através de workshops de grupos focais realizados junto de educadores, futuros educadores e outros profissionais da educação. Estes permitiram avaliar, através do debate e discussão, as opiniões e perceções dos participantes sobre os recursos produzidos no âmbito do projeto e a sua adequação para a exploração da literacia mediática de crianças. Obtiveram-se considerações positivas quanto à relevância (especialmente pela COVID-19), utilidade, transferência de conhecimentos e competências. Os produtos construídos e as descobertas alcançadas serão discutidas quanto às suas implicações para as práticas de literacia mediática nos contextos europeus de jardim de infância. Serão apresentadas recomendações para decisores políticos, formadores na formação inicial e contínua de profissionais de educação de infância, profissionais de educação de infância e investigadores.info:eu-repo/semantics/publishedVersio