Proximity induced topological state in graphene

The appearance of topologically protected states at the surface of an ordinary insulator is a rare occurrence and to date only a handful of materials are known for having this property. An intriguing question concerns the possibility of forming topologically protected interfaces between different materials. Here we propose that a topological phase can be transferred to graphene by proximity with the three-dimensional topological insulator Bi$_2$Se$_3$. By using density functional and transport theory we prove that, at the verge of the chemical bond formation, a hybrid state forms at the graphene/Bi$_2$Se$_3$ interface. The state has Dirac-cone-like dispersion at the $\Gamma$ point and a well-defined helical spin-texture, indicating its topologically protected nature. This demonstrates that proximity can transfer the topological phase from Bi$_2$Se$_3$ to graphene.Comment: 6 pages, 4 figure

Dynamical symmetries and crossovers in a three-spin system with collective dissipation

We consider the non-equilibrium dynamics of a simple system consisting of interacting spin-$1/2$ particles subjected to a collective damping. The model is close to situations that can be engineered in hybrid electro/opto-mechanical settings. Making use of large-deviation theory, we find a Gallavotti-Cohen symmetry in the dynamics of the system as well as evidence for the coexistence of two dynamical phases with different activity levels. We show that additional damping processes smoothen out this behavior. Our analytical results are backed up by Monte Carlo simulations that reveal the nature of the trajectories contributing to the different dynamical phases.Comment: 6 pages, 5 figure

Quantum thermodynamics of boundary time-crystals

Time-translation symmetry breaking is a mechanism for the emergence of non-stationary many-body phases, so-called time-crystals, in Markovian open quantum systems. Dynamical aspects of time-crystals have been extensively explored over the recent years. However, much less is known about their thermodynamic properties, also due to the intrinsic nonequilibrium nature of these phases. Here, we consider the paradigmatic boundary time-crystal system, in a finite-temperature environment, and demonstrate the persistence of the time-crystalline phase at any temperature. Furthermore, we analyze thermodynamic aspects of the model investigating, in particular, heat currents, power exchange and irreversible entropy production. Our work sheds light on the thermodynamic cost of sustaining nonequilibrium time-crystalline phases and provides a framework for characterizing time-crystals as possible resources for, e.g., quantum sensing. Our results may be verified in experiments, for example with trapped ions or superconducting circuits, since we connect thermodynamic quantities with mean value and covariance of collective (magnetization) operators.Comment: 7+6 pages, 2+1 figure

Predicting school achievement rather than intelligence: does metacognition matter?

This paper investigates the role of specific and general metacognitive ability on specific and general academic achievement, controlling for the effects of intelligence. Four hypotheses were elaborated and empirically tested through structural equation modelling. The sample was composed by 684 students (6th to 12th graders) from a private Brazilian school, which answered to three intelligence tests and three metacognitive tests. The modeled hypotheses presented a good data-fit (χ² = 51.18; df = 19; CFI = 1.00; RMSEA = 0.05), showing that the general metacognitive ability explained general academic achievement rather than intelligence, but did not explain specific academic achievement. On the other hand, specific metacognitive ability explained specific academic achievement rather than intelligence, but did not explain general academic achievement. The predictive power of the general metacognitive ability was greater than fluid intelligence in the explanation of general academic achievement. In the same line, specific metacognitive ability had a greater predictive power than intelligence and specific knowledge in the explanation of specific academic achievement. Finally, a new structural model of metacognition and its role in academic achievement are proposed

Oral loading of propafenone: restoring its role before restoring rhythm

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Cardiac resynchronization therapy in persistent left superior vena cava: Can you do it two-leads-only?

Cardiac resynchronization therapy in persistent left superior vena cava: Can you do it two-leads-only

A Study on the Use of Checksums for Integrity Verification of Web Downloads

App stores provide access to millions of different programs that users can download on their computers. Developers can also make their programs available for download on their websites and host the program files either directly on their website or on third-party platforms, such as mirrors. In the latter case, as users download the software without any vetting from the developers, they should take the necessary precautions to ensure that it is authentic. One way to accomplish this is to check that the published file’s integrity verification code – the checksum – matches that (if provided) of the downloaded file. To date, however, there is little evidence to suggest that such process is effective. Even worse, very few usability studies about it exist. In this paper, we provide the first comprehensive study that assesses the usability and effectiveness of the manual checksum verification process. First, by means of an in-situ experiment with 40 participants and eye-tracking technology, we show that the process is cumbersome and error-prone. Second, after a 4-month long in-the-wild experiment with 134 participants, we demonstrate how our proposed solution – a Chrome extension that verifies checksums automatically – significantly reduces human errors, improves coverage, and has only limited impact on usability. It also confirms that, sadly, only a tiny minority of websites that link to executable files in our sample provide checksums (0.01%), which is a strong call to action for web standards bodies, service providers and content creators to increase the use of file integrity verification on their properties

Social networks, social capital and environmental governance in the Amazonian Gateway Territory

O artigo trata de um estudo empírico em que a análise de redes sociais é utilizada para mapear o capital social de atores envolvidos em processos de governança ambiental na Amazônia brasileira. Por meio de entrevistas, foi mapeada a rede de relações de diálogo sobre questões socioambientais de um conjunto de 505 atores no Território Portal da Amazônia. Foram identificadas 3384 relações de diálogo, com uma média de 6,7 parceiros de diálogo por ator. A análise dos aspectos estruturais da rede de diálogo foi utilizada para construir indicadores de capital social de ligação, com mapeamento da organização interna dos atores de um mesmo município, e de conexão, com a caracterização das relações entre atores de municípios diferentes. Em nível municipal, a distribuição das duas formas de capital social permitiu caracterizar os grupos de atores de acordo com as suas atuações diferenciadas na governança ambiental do Território. Em nível territorial, o padrão de conectividade entre os 16 municípios mostra um equilíbrio entre as duas formas de capital social e revela o potencial de comunicação e organização dos atores, como demonstrado no exemplo dos projetos de Agendas 21 locais. Estes resultados demonstram como a análise de redes sociais pode contribuir na definição (ou redefinição) das fronteiras dos territórios de modo a incluir um conjunto de municípios cujos atores mantêm relações sociais efetivas. Ações de governança no Portal da Amazônia são propostas com potencial para fortalecer os processos de diálogo, diminuir os conflitos e promover o uso sustentável dos recursos naturais na Amazônia.The article presents an empirical study where social network analysis is used to map social capital among actors involved in environmental governance processes in the Brazilian Amazon. Using interviews, we carried out the mapping of the dialogue network regarding socio-environmental issues among 505 actors from the Amazonian Gateway Territory. The analysis identified 3384 dialogue relationships. Each actor has an average of 6,7 dialogue partners. The analysis of the structural characteristics of the dialogue network was used to build indicators of social capital of the bonding type, based on the mapping of the organization among actors from the same municipalities, and bridging type, based on the identification of relationships among actors from different municipalities. At the municipal level, the distribution of the two types of social capital allowed the characterization of groups of actors according to their differing participation in the environmental governance of the Territory. At the territorial level, the connectivity pattern among the 16 municipalities exhibits a balance between the two types of social capital and reveals the potential of communication and organization among actors, as demonstrated through the example of the local Agenda 21 projects. These results demonstrate how social network analysis can contribute to the definition (or re-definition) of the territories frontiers in order to include a set of municipalities whose cohesion is based on effective social relationships. We also propose governance actions for the Amazonian Gateway aiming at strengthening dialogue processes, reducing conflicts and promoting the sustainable use of natural resources in the Amazon

DENGUE NO BRASIL: TEMA DE EDUCAÇÃO AMBIENTAL E SUAS QUESTÕES METODOLÓGICAS

Não diferente de outros países do mundo, o Governo brasileiro ao longo de décadas enfrenta umgrande problema em saúde pública que é a Dengue. Também não diferente de outros países, as ações decombate ao vetor desta Doença, que é um mosquito, se deu através de intervenções mecânicas, executadaspor agentes de saúde no campo. A educação ambiental nunca recebeu tanta atenção quanto hoje, nabusca de soluções para o problema da Dengue, porém ainda há problemas quanto a sua fundamentação.O caráter objetificador presente na maioria das metodologias modernas, impossibilita uma melhor compreensãoe relação do homem com o meio onde vive. A hermenêutica filosófica de Gadamer nos possibilitater novos olhares para com a educação ambiental.Palavras-chave: dengue no Brasil, educação ambiental, hermenêutica