Subtle leakage of a Majorana mode into a quantum dot

We investigate quantum transport through a quantum dot connected to source and drain leads and side-coupled to a topological superconducting nanowire (Kitaev chain) sustaining Majorana end modes. Using a recursive Green's function approach, we determine the local density of states (LDOS) of the system and find that the end Majorana mode of the wire leaks into the dot thus emerging as a unique dot level {\it pinned} to the Fermi energy $\varepsilon_F$ of the leads. Surprisingly, this resonance pinning, resembling in this sense a "Kondo resonance", occurs even when the gate-controlled dot level $\varepsilon_\text{dot}(V_g)$ is far above or far below $\varepsilon_F$. The calculated conductance $G$ of the dot exhibits an unambiguous signature for the Majorana end mode of the wire: in essence, an off-resonance dot [$\varepsilon_\text{dot}(V_g)\neq \varepsilon_F$], which should have $G=0$, shows instead a conductance $e^2/2h$ over a wide range of $V_g$, due to this pinned dot mode. Interestingly, this pinning effect only occurs when the dot level is coupled to a Majorana mode; ordinary fermionic modes (e.g., disorder) in the wire simply split and broaden (if a continuum) the dot level. We discuss experimental scenarios to probe Majorana modes in wires via these leaked/pinned dot modes.Comment: 3 figures, 5 pages, published in Phys. Rev. B (Editors' suggestion

Open space system as an armature for urban expansion: evaluation of landscape ecological spatial concepts as a model for improving resilience in urban systems

Urbanization alters several attributes of natural resources, degrading ecosystems and causing them to lose their ability to maintain their structure and function. As a result, native ecosystems in territories subject to urban expansion lose qualities important to their self-organization and may, in certain cases, disappear altogether. Actions that protect or strengthen the resilience of these native ecosystems in the face of urban development may offer increased capacity for these native ecosystems to survive and endure. Landscape ecology aims to understand the relationship between spatial patterns and ecological processes across scales (Wu, 2008) considering the interaction with human activities (Naveh & Lieberman, 1984). A landscape is a kilometers-wide area (Forman & Godron, 1981), comprising a heterogeneous area where ecosystems are repeated in similar form and interact (Forman, 1995b; Forman & Godron, 1986; Forman & Godron, 1981). Wu argues that a landscape ecological perspective is more comprehensive than other approaches for a number of reasons: consideration of operational scales (watershed or metropolitan area); hierarchical and integrative ecological basis; trans and interdisciplinary approaches to study nature-society interactions; theories and methods for studying relationships between spatial pattern and biophysical and socioeconomic processes; methods and metrics to asses sustainability; and “theoretical and methodological tools for dealing with scaling and uncertainty issues” (Wu, 2008). My concern is primarily with how the spatial arrangement of urban land use and land cover influences the survival of ecosystems as cities expand. I propose to address one over-arching question, with two sub-questions within it. The overarching question is: Does applying landscape ecological spatial concepts in the design of urban open space systems have an effect on resilience of ecosystems as they experience urbanization? Urban open space system is defined here as the network of areas in a city that provide habitat for native wildlife and the connections among them; comprised of riparian forests, patches of native vegetation, and woodlots. As urban places, these areas also offer opportunities for people. They provide recreational opportunities and amenities; include parks, plazas, and streets. There is a biophysically-related sub-question: What are the key biophysical processes that are important to address to minimize loss of native biodiversity in urban open spaces? There is also a culturally-related sub-question: What are the urban expansion policies and actions that, if applied to open space planning, will minimize loss of the patterns and processes necessary for native ecological processes to endure in the face of urbanization? This article is a first step to answer the second question. First, it presents a review of landscape ecological approaches as have been investigated and applied in landscape planning and an examination at how spatial solutions have been proposed for landscape planning. Second, a case study is chosen; a review of state of Oregon’s and Portland Metro’s approach to managing urban expansion. The study area is an urban reserve in the Portland Metro region created through application of Oregon Senate Bill 1011, which determines that Metro Portland and Clackamas, Multnomah, and Washington counties define together “which lands outside the current urban growth boundary are best suited to accommodate urban development over the next 40 to 50 years and which lands should be off limits to development in order to protect their values as farms, forests and natural areas during that same period” (Metro) (Figure 4 and Figure 5)

Microbiological safety aspects of mangoes (Mangifera indica) and papayas (Carica papaya): a mini-review.

Abstract: This review describes several aspects related to microbiological safety in mangoes and papayas, such as incidence, outbreaks, internalisation and growth/survival of bacterial pathogens. Mangoes and papayas are often served sliced in food establishments in fresh pieces at salad bars, deli counters and as pulp juice. In general, these products do not undergo any process to eliminate pathogenic microorganisms before consumption, and a long shelf life could theoretically provide time for these microorganisms to multiply without affecting the organoleptic qualities of the fruit, thereby increasing the risks of food-borne illness. The data presented in this review show that low temperatures can impede microbial growth, but not completely inhibit such growth in mangoes and papayas. Highest growth rates were observed in the range between 22 and 37oC. In the last 20 years, several outbreaks of salmonellosis caused by these fruits or by food made with these fruits have been reported. The control of the temperature in the fruit washing water is important to prevent the internalisation of Salmonella spp. The implementation of strategies such as Good Agricultural Practices, Good Manufacturing Practices and Hazard Analysis Critical is important, as these methods can eliminate or significantly reduce microbial contamination. Resumo: Esta revisão descreve diversos aspectos relacionados à segurança microbiológica em manga e mamão papaya como; incidência, surtos, internalização e crescimento/sobrevivência de patógenos acterianos nestas frutas. Mangas e papayas são frequentemente servidas fatiadas em estabelecimentos alimentícios como pedaços frescos, em misturas para saladas, expostas em balcões e como polpas de frutas. No geral, estes produtos não passam por qualquer processo para eliminar microrganismos patogênicos antes do seu consumo e uma vida longa de prateleira poderia teoricamente fornecer tempo para que estes microrganismos se multipliquem sem afetar as qualidades organolépticas destas frutas e assim aumentar o risco de doenças de origem alimentar. Os dados apresentados nesta revisão mostram que baixas temperaturas podem diminuir o crescimento de microrganismos mas não inibi-los em mangas e papayas. Os melhores crescimentos foram observados na faixa de 22?37oC. Nos últimos 20 anos diversos surtos de salmonelose nestas frutas ou produtos feitos com as mesmas foram relatados. O controle da temperatura da água de lavagem de frutas é importante para prevenir a internalização de Salmonella spp. A implementação de estratégias como Boas Práticas Agrícolas, Boas Práticas de Produção e Análise Crítica de Pontos de Controle são importantes já que podem eliminar ou reduzir significantemente a contaminação microbiana

Produção de forragem de pastos de inverno submetida a níveis de adubação nitrogenada e diferentes intensidades de pastejo

Projeto acadêmico (graduação) - Universidade Federal de Santa Catarina. Campus Curitibanos. Ciências Rurais.O sistema de Integração Lavoura-Pecuária (ILP) adquiriu destaque nos últimos anos por ser uma estratégia de sustentabilidade e renda para produtores rurais na estação hibernal com o uso de pastagem cultivada para criação de animais após o cultivo de verão. A aveia preta (Avena strigosa Schreb.) e o azevém (Lolium multiflorum Lam.) são muito empregadas para cobertura do solo sob semeadura direta; na região Sul não é habitual a adubação dos pastos, se usa o efeito residual da cultura estival. Para garantir a produtividade e lucratividade é necessária a adoção de técnicas de manejo para manter produção de forragem, pois se a intensidade de pastejo for alta, serão necessárias maiores doses de fertilizantes nitrogenados para melhorar o perfilhamento. Objetiva-se neste trabalho avaliar a produção de forragem de aveia preta e azevém em diferentes intensidades de pastejo e níveis de adubação nitrogenada. O projeto será implantado na área de ILP da fazenda experimental Campo da Roça, pertencente à Universidade Federal de Santa Catarina, com solo classificado em Cambissolo Háplico de textura argilosa. O experimento será implantado em esquema fatorial 2x2 com quatro repetições, sendo os fatores alturas de pastejo 15 e 7 cm e duas doses de nitrogênio 50 e 150 kg de N/ha, numa área de 2 hectares, dividida em quatro blocos, cada bloco será dividido em quatro, totalizando 16 piquetes de 0,12 hectares. A análise estatística será feita pelo Teste F de Fisher e quando significativo será aplicado o Teste de Duncan para comparações entre as médias, ambos com 5% de significância. Será avaliada a massa de forragem, o acúmulo de forragem, a taxa de acúmulo e a produção de forragem. Com isso, espera-se oferecer alternativas sobre uso de pastagens em ILP, dispor alimento de qualidade e quantidade para os animais, aumentar a taxa de lotação animal por área, reduzir o tempo de permanência dos animais na propriedade e gerar renda para o produtor na época hibernal

Persistent Skyrmion Lattice of Noninteracting Electrons with Spin-Orbit Coupling

A persistent spin helix (PSH) is a robust helical spin-density pattern arising in disordered 2D electron gases with Rashba $\alpha$ and Dresselhaus $\beta$ spin-orbit (SO) tuned couplings, i.e., $\alpha=\pm\beta$. Here we investigate the emergence of a Persistent Skyrmion Lattice (PSL) resulting from the coherent superposition of PSHs along orthogonal directions -- crossed PSHs -- in wells with two occupied subbands $\nu=1,2$. For realistic GaAs wells we show that the Rashba $\alpha_\nu$ and Dresselhaus $\beta_\nu$ couplings can be simultaneously tuned to equal strengths but opposite signs, e.g., $\alpha_1= \beta_1$ and $\alpha_2=-\beta_2$. In this regime and away from band anticrossings, our {\it non-interacting} electron gas sustains a topologically non-trivial skyrmion-lattice spin-density excitation, which inherits the robustness against spin-independent disorder and interactions from its underlying crossed PSHs. We find that the spin relaxation rate due to the interband SO coupling is comparable to that of the cubic Dresselhaus term as a mechanism of the PSL decay. Near anticrossings, the interband-induced spin mixing leads to unusual spin textures along the energy contours beyond those of the Rahsba-Dresselhaus bands. Our PSL opens up the unique possibility of observing topological phenomena, e.g., topological and skyrmion Hall effects, in ordinary GaAs wells with non-interacting electrons.Comment: 5 pages, 2 figures; changed the presentation and added supplemental material (17 pages, 1 figure

Chinese outbound tourists: profile and perceptions of Portugal

O objetivo deste estudo é disponibilizar informação mais aprofundada sobre o perfil da futura geração de turistas Chineses e explorar as suas percepções sobre Portugal enquanto destino turístico. A procura dos turistas Chineses por viagens no estrangeiro bem como as suas preferências devem ser do conhecimento dos agentes da indústria do turismo para que possam corresponder às expectativas deste mercado. A análise de factores como as políticas implementadas pelo governo no âmbito do turismo emissor contribuirão para melhor compreender o desenvolvimento do turismo da China. A consciência e perceção de Portugal enquanto destino turístico entre a futura geração de turistas Chineses constituem questões importantes a serem estudadas. Este estudo evidencia o tipo de turista Chinês e as tendências da futura geração de turistas, pois com o aumento médio dos vencimentos, a globalização e um novo estilo de vida estão a aparecer novos grupos de turistas. A pesquisa através de um questionário a alunos de licenciaturas e mestrados evidencia as características e tendências do turismo para o estrangeiro na perspectiva deste nicho da nova geração de turistas. Este questionário apresenta os resultados do estudo que determina os atributos que são considerados mais importantes na experiência global dos turistas Chineses que poderão vir a viajar para Portugal.The aim of this study is to provide an in depth insight into the tourist profile of the future Chinese generation and to explore its perceptions of Portugal as a tourism destination. As the demand for outbound travel in China increases, interests about tourism activities should be known by the agents of tourism industry, so that the expectations of these tourists can be met. The analyses of factors such as government policies concerning outbound travel in the tourism industry, will largely contribute to better understand the development of Chinese tourism activity. The awareness and perception of Portugal as a tourism destination amongst Chinese future tourists is one of the important aspects to be studied. This study outlines the type of Chinese tourist and the trends with new groups of tourists appearing. This is becoming a reality due to the increase of average income, globalization and a new lifestyle. A survey questionnaire distributed amongst undergraduate and post-graduate students will highlight the characteristics and trends emerging in outbound tourism according to their opinions and perceptions. This survey presents the findings that determine the critical factors to the overall experience of Chinese tourists that would travel to Portugal in the future