Raman laser spectroscopy of Wannier Stark states

Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow 1D vertical lattice. For long enough laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. All these features allow for a precise characterization of the trapping potential and for an efficient control of the atoms external degrees of freedom

State labelling Wannier-Stark atomic interferometers

Using cold 87Rb atoms trapped in a 1D-optical lattice, atomic interferometers involving coherent superpositions between different Wannier-Stark atomic states are realized. Two di fferent kinds of trapped interferometer schemes are presented: a Ramsey-type interferometer sensitive both to clock frequency and external forces, and a symmetric accordion-type interferometer, sensitive to external forces only. We evaluate the limits in terms of sensitivity and accuracy of those schemes and discuss their application as force sensors. As a first step, we apply these interferometers to the measurement of the Bloch frequency and the demonstration of a compact gravimeter.Comment: 11 page

Towards delay-aware container-based Service Function Chaining in Fog Computing

Recently, the fifth-generation mobile network (5G) is getting significant attention. Empowered by Network Function Virtualization (NFV), 5G networks aim to support diverse services coming from different business verticals (e.g. Smart Cities, Automotive, etc). To fully leverage on NFV, services must be connected in a specific order forming a Service Function Chain (SFC). SFCs allow mobile operators to benefit from the high flexibility and low operational costs introduced by network softwarization. Additionally, Cloud computing is evolving towards a distributed paradigm called Fog Computing, which aims to provide a distributed cloud infrastructure by placing computational resources close to end-users. However, most SFC research only focuses on Multi-access Edge Computing (MEC) use cases where mobile operators aim to deploy services close to end-users. Bi-directional communication between Edges and Cloud are not considered in MEC, which in contrast is highly important in a Fog environment as in distributed anomaly detection services. Therefore, in this paper, we propose an SFC controller to optimize the placement of service chains in Fog environments, specifically tailored for Smart City use cases. Our approach has been validated on the Kubernetes platform, an open-source orchestrator for the automatic deployment of micro-services. Our SFC controller has been implemented as an extension to the scheduling features available in Kubernetes, enabling the efficient provisioning of container-based SFCs while optimizing resource allocation and reducing the end-to-end (E2E) latency. Results show that the proposed approach can lower the network latency up to 18% for the studied use case while conserving bandwidth when compared to the default scheduling mechanism

Integral Rural Reform and Democratic Opening for Peace Building: Transitional Justice in Colombia

This article deals with the transitional process in development in the neighboring country after the end of a conflict that lasted for more than fifty years involving guerrilla movements paramilitary groups and public forces in Colombia Its goal is to analyze two of the most peculiar aspects of the agreement between the protagonists of the confrontations integral rural reform and democratic opening for the peace building Firstly the peculiar dynamics that involve law and politics in times of transition are highlighted and then the peace process itself Then it moves on to the two points mentioned in the agreement discussing how the obligations assumed by Colombian society with regard to expanding access to land and conducting political reform are in line with the idea of non-repetition that should guide transitional process It is discussed how the agrarian question related to the origin and performance of the FARC-EP guerrilla movement could not be absent from the context of the agreement signed while at the same time reflecting on the need to change the electoral system as an imperative for the expansion of competition in electoral disputes which would convince those historically marginalized movements to surrender their arms and believe in the coming to power by the vote It is concluded at the end that Colombia can learn from transitional experiences of other countries emerging from conflicts of a similar nature but that some of the peculiarities of the decades of history of the confrontation led to the insertion of different conditions in the negotiations resulting in the renunciation of the conflict Another conclusio

Modelagem de núcleos em colméia na análise mecânica de painéis-sanduíche

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2019.Este trabalho apresenta um estudo sobre a reposta elástica a carregamentos mecânicos de painéis-sanduíche constituídos por faces compósitas ortotrópicas e núcleo em colmeia hexagonal regular, focando na influência do núcleo neste comportamento. Deseja-se validar a utilização de propriedades elásticas aproximadas encontradas na literatura para a criação de um modelo contínuo simplificado que represente a colmeia. Para tanto, simulações em métodos de elementos finitos são utilizadas na obtenção das propriedades equivalentes de placas em colméia de diferentes tamanhos e seus resultados são comparados aos valores previstos pelas equações presentes na literatura. Busca-se ainda estudar a funcionalidade de diferentes tipos de simplificação da geometria nuclear para a redução do custo computacional de análises numéricas. Isso é realizado pela solução de problemas flexurais envolvendo painéis-sanduíche pela ótica de diferentes níveis de simplificação de núcleo, comparando o comportamento resultante entre si e com soluções analíticas conhecidas. Essas análises mostram um aumento de até 1% nas deflexões de modelos que utilizem propriedades calculadas analiticamente, quando comparados àqueles que fazem uso de propriedades obtidas numericamente, e uma variação de até 6% nas respostas obtidas através de diferentes modelos de simplificação (sendo tomada como referência a representação completa da geometria nuclear hexagonal por meio de elementos de casca).The current report presents a study on the elastic response to mechanical loads of sandwich panels formed by orthotropic composite faces, and regular hexagonal honeycomb core, focusing on the core’s influence on its behavior. It is intended to validate the use of approximated elastic properties found in literature for the creation of a simplified continuous model that represents the honeycomb structure. Therefore, finite element simulations are used to obtain equivalent properties for different sized honeycombs and their results are compared to those obtained from equations defined in the literature. It aims as well to study the viability of using different types of nuclear geometry simplification to reduce the computational cost of numerical analyses. That is done by solving flexural problems in sandwich panels by means of different levels of core simplification, comparing their behavior to those of other models and to known analytical solutions. Those analyses show as much as 1% deflection increase for models using analytical calculated properties, when compared to those with properties acquired numerically, and up to 6% contrast between different simplification models (using a complete shell representation of honeycomb hexagonal geometry as reference model)

Performance-based design: report of an academic workshop with energy efficiency simulation tools

This article presents the results of a Seminar/Workshop named “Energy Modelling: Preliminary Analysis of an Architecture Project”, organised at the University of Minho's School of Architecture, Art and Design, located in Guimarães. The Seminar/Workshop aimed to teach students on the use of simulation tools that evaluate the energy performance of building's architectural design. It demonstrates the importance of simulation software as a tool to design energy-efficient architecture in the early stages of a project. The Seminar/Workshop introduced students to fundamental notions of simulation related to thermal and natural lighting comfort, like modelling methods, interpreting the obtained results and procedures for improving the results. Despite presenting different simulation software during the workshop, the exercises proposed to the students focused on using Climate Studio because of its versatility and compatibility with different architectural modelling software. The software is relatively recent and can be adapted in different project phases. The students learned the benefits of using simulation software to obtain information for further improving an architectural project. The simulation helped students understand the passive design strategies that can improve thermal comfort in the building. Like making the best use of the landscape, the shape of the building and its position and not just by increased insulation in the envelope, well-oriented glazing, optimised thermal mass, controlled ventilation or shading. Therefore, the students learn that simulation tools allow for optimising the passive strategies to their limits in the design stage.Funding of the Landscape, Heritage and Territory Laboratory (Lab2PT), Ref. UID/04509/2020, financed by national funds (PIDDAC) through the FCT/MCTE

Evidence from electronic payments

This paper uses novel and comprehensive data on electronic payments from SIBS, the main provider of point of sale terminals and on-line payments in Portugal, to study the impact of the Great Lockdown on purchases. The data aggregates all individual transactions into monthly observations, by municipality and sector, between 2018 and 2020. We employ a difference-in-differences event study that relies on the assumption that the monthly evolution of purchases in the first four months of 2020 would be parallel to that of the two previous years. We identify a massive causal impact on overall purchases, from a baseline year-on-year monthly growth rate of 10% to a decrease of 45%. The sign and magnitude of the impact varies considerably across sectors. Purchases of essential goods such as supermarkets and groceries increase mildly, contrasting with severe contractions in sectors that were closed by government order or depend heavily on tourism, including the leisure industry and restaurants. We find suggestive evidence of initial stockpiling of goods, postponing of essential expenditures, and rapid recovery of purchases in tech and entertainment, possibly to adapt to the confinement. Transactions with foreign-owned cards cause an even greater negative contraction. We disentangle the total effect into the intensive margin of the average transaction and the extensive margin of the number of transactions. Buyers adjust their shopping strategies in rational ways to minimize public health risks: they go less often to supermarkets and buy more each time, and visit local groceries more.publishersversionpublishe

Laser controlled tunneling in a vertical optical lattice

Raman laser pulses are used to induce coherent tunnelling between neighbouring sites of a vertical 1D optical lattice. Such tunneling occurs when the detuning of a probe laser from the atomic transition frequency matches multiples of the Bloch frequency, allowing for a spectroscopic control of the coupling between Wannier Stark (WS) states. In particular, we prepare coherent superpositions of WS states of adjacent sites, and investigate the coherence time of these superpositions by realizing a spatial interferometer. This scheme provides a powerful tool for coherent manipulation of external degrees of freedom of cold atoms, which is a key issue for quantum information processing