Holographic Relaxation of Finite Size Isolated Quantum Systems

We study holographically the out of equilibrium dynamics of a finite size closed quantum system in 2+1 dimensions, modelled by the collapse of a shell of a massless scalar field in AdS4. In global coordinates there exists a variety of evolutions towards final black hole formation which we relate with different patterns of relaxation in the dual field theory. For large scalar initial data rapid thermalization is achieved as a priori expected. Interesting phenomena appear for small enough amplitudes. Such shells do not generate a black hole by direct collapse, but quite generically an apparent horizon emerges after enough bounces off the AdS boundary. We relate this bulk evolution with relaxation processes at strong coupling which delay in reaching an ergodic stage. Besides the dynamics of bulk fields, we monitor the entanglement entropy, finding that it oscillates quasi-periodically before final equilibration. The radial position of the traveling shell is brought into correspondence with the evolution of the entanglement pattern in the dual field theory. The entanglement entropy is not only able to portrait the streaming of entangled excitations, but it is also a useful probe of interaction effects.Comment: 37 pages, 27 figure

Collapse and Revival in Holographic Quenches

We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals

Benefits of using biogas in households experience from a user in Uganda

A Sendegeya, P J M Ssebuwufu and I P da SilvaMakerere University and Ssebuwufu AssociatesThis paper discusses the socio-economic benefits of using biogas based on the experience of a long term user as a typical example. A floating drum type of digester was installed with a capacity of 6.5 m3 in the year 2000 at a total cost of US$1,830. The gas generated is used exclusively for cooking. For the user, his typical kitchen day consists of three meals for a household of 8 people. Prior to the installation of the biogas plant, the user was using liquefied petroleum gas (LPG) supplied in 15 kg cylinders at an average cost of US$ 23 per cylinder and used to consume an average of 3 cylinders in 2 months bringing a monthly expenditure on the kitchen fuel of US$35 including transport costs for the cylinder. The user has now totally substituted LPG with biogas which translates into an annual average saving of US$ 420. At this rate of saving, the break-even point for the full recovery of the installation costs is about five years. Since installation the digester has not had any significant breakdown, so no major maintenance has been required. The water used for mixing the cow dung into slurry is harvested rainwater. Thus according to his experience it indicates that the use of biogas offers a substantial cost saving on domestic energy. In addition to the economic benefits, other benefits include increased organic agricultural production when the sludge is used as fertiliser. The use of the slurry as bio-fertiliser on his small vegetable farm (about 0.5 ha), has helped him to save money that would have been used to buy the imported artificial fertilisers. Fermenting the cow dung in a biogas digester instead of composting it in open air provides several other advantages, ranging from a foul odour-free environment to improvements in the general health conditions in the home. Thus, a reduction in the unhealthy smell from the compost dumps where the cow dung used to be deposited, as well as a reduction in free methane gas (one of the green house gases, GHG) which used to be emitted direct into the atmosphere by the decomposing dung.This paper discusses the socio-economic benefits of using biogas based on the experience of a long term user as a typical example. A floating drum type of digester was installed with a capacity of 6.5 m3 in the year 2000 at a total cost of US$1,830. The gas generated is used exclusively for cooking. For the user, his typical kitchen day consists of three meals for a household of 8 people. Prior to the installation of the biogas plant, the user was using liquefied petroleum gas (LPG) supplied in 15 kg cylinders at an average cost of US$ 23 per cylinder and used to consume an average of 3 cylinders in 2 months bringing a monthly expenditure on the kitchen fuel of US$35 including transport costs for the cylinder. The user has now totally substituted LPG with biogas which translates into an annual average saving of US$ 420. At this rate of saving, the break-even point for the full recovery of the installation costs is about five years. Since installation the digester has not had any significant breakdown, so no major maintenance has been required. The water used for mixing the cow dung into slurry is harvested rainwater. Thus according to his experience it indicates that the use of biogas offers a substantial cost saving on domestic energy. In addition to the economic benefits, other benefits include increased organic agricultural production when the sludge is used as fertiliser. The use of the slurry as bio-fertiliser on his small vegetable farm (about 0.5 ha), has helped him to save money that would have been used to buy the imported artificial fertilisers. Fermenting the cow dung in a biogas digester instead of composting it in open air provides several other advantages, ranging from a foul odour-free environment to improvements in the general health conditions in the home. Thus, a reduction in the unhealthy smell from the compost dumps where the cow dung used to be deposited, as well as a reduction in free methane gas (one of the green house gases, GHG) which used to be emitted direct into the atmosphere by the decomposing dung

Technical, Economic and Sustainability Considerations of a Solar PV Mini Grid as a Tool for Rural Electrification in Uganda

The challenges facing rural electrification in Uganda are diverse with less than 3% of the rural population having access to electricity. The establishment of mini-grids powered by renewable energy sources makes it possible to electrify remote areas at affordable rates. In this study, an assessment of a solar PV mini-grid system to provide electricity to forty households in rural Uganda was carried out. The considered system comprised six solar modules each rated 175 Wp, a controller, off-grid inverter and batteries with a capacity of 600 Ah. Manufactured by SMA, the Sunny Island inverter proposed for the mini-grid would ensure provision of grid-quality electricity. The study aimed to investigate the mini-grid’s technical design with focus on optimal distribution against constraints of voltage drops, electrical losses and increasing load. Customised load limiters shared between households using thermistors were included to reduce costs and limit consumption. The incomes of rural households are often seasonal and thus issues pertaining to affordability and sustainability were also considered. Results of the economic analysis showed a payback period of less than 5 years given an affordable fixed monthly tariff for the case study area

Holographic quenches with a gap

In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.The work of E.daS. is nanced by the spanish grant BES-2013-063972. E.L. has been supported by the spanish grant FPA2012-32828 and SEV-2012-0249 of the Centro de Excelencia Severo Ochoa Programme. The work of J.M. is supported in part by the spanish grant FPA2011-22594, by Xunta de Galicia (GRC2013- 024), by the Consolider-CPAN (CSD2007-00042), and by FEDER. A.S. is supported by the European Research Council grant HotLHC ERC-2011-StG-279579 and by Xunta de Galicia (Conselleria de Educaci on). Part of the numerical calculations were performed at the Centro de Supercomputaci on de Galicia (CESGA).S

Design and construction recommendations for brick enclosures with continuous air chamber

Brick façades enclosures traditionally used in residential architecture in Spain generate stability, insulation and waterproofing problems. Self-supporting enclosures with continuous air chamber solve these problems. The aim of this study is to analyze the mechanical behaviour of enclosure with continuous air chamber to define design recommendations. The study of a standard three-story façade using the Finite Element Method shows the stresses, displacements and cracking. The areas subjected to greater stresses are located on the top floor wall, concentrated around the openings and close to connection keys. Constructive solutions are proposed to build this enclosure from the foundation to the top of the building taking into account the requirement of stability, insulation and waterproofing. The addition of steel reinforcement in the horizontal mortar joints in cracked areas and connection keys at the top of the building solves the requirement of stability. © 2012 Elsevier Ltd. All rights reserved.Cubel Arjona, FJ.; Mas Tomas, MDLA.; Vercher Sanchis, JM.; Gil Benso, E. (2012). Design and construction recommendations for brick enclosures with continuous air chamber. Construction and Building Materials. (36):151-164. doi:10.1016/j.conbuildmat.2012.04.128S1511643

Medición y evaluación de valores en contenidos audiovisuales desde un abordaje interdisciplinar

El siguiente estudio interdisciplinar realizado por LAICOM (Laboratorio de Análisis Instrumental de la Comunicación, UAB), parte de la revisión del concepto de calidad comunicativa y formula un inventario de 26 valores para el ámbito iberoamericano, seleccionados aplicando el análisis de contenido a tres documentos de gran consenso social: "Carta de Derechos Humanos" (1948), "Constitución Federal de Brasil" (1988) y "Constitución Española" (1978). Los valores se han definido en sus dimensiones social, humana y educativa. Finalmente, se propone y valida un protocolo basado en test de recepción, capaz de medir y comparar la carga de valores transmitida en cualquier proceso de comunicación. El protocolo ha sido experimentado y corregido aplicándolo a 2 grupos de 10 expertos que evaluaron 4 spots publicitarios, con los que, luego, se organizaron sendos grupos de discusión.This interdisciplinary research, carried out by LAICOM reviews the concept quality communication and designs a 26 values glossary within the ibero-American context. Values are selected by applying a content analysis to 3 documents of feat social consensus: the "Human Rights Act" (1948), the "Federal Brazilian Constitution" (1988), and the "Spanish Constitution (1978); and are defined in three dimensions: human, social and education. Finally, a protocol is proposed and validated by a test of reception, which serves to measure and compare the load of values transmitted by any process of communication. This protocol is tested and corrected through two focus groups of communication experts (10 each), who first had to evaluate 4 TV ads and second discuss about results collected

Aedes albopictus diversity and relationships in south-western Europe and Brazil by rDNA/mtDNA and phenotypic analyses: ITS-2, a useful marker for spread studies

Background: Aedes albopictus is a very invasive mosquito, which has recently colonized tropical and temperate regions worldwide. Of concern is its role in the spread of emerging or re-emerging mosquito-borne diseases. Ae. albopictus from south-western Europe and Brazil were studied to infer genetic and phenetic diversity at intra-individual, intra-population and inter-population levels, and to analyse its spread. Methods: Genotyping was made by rDNA 5.8S-ITS-2 and mtDNA cox1 sequencing to assess haplotype and nucleotide diversity, genetic distances and phylogenetic networks. Male and female phenotyping included combined landmark-and outlined-based geometric morphometrics of wing size and shape. Results: Specimens from seven populations from Spain, France and Brazil provided 12 cox1 and 162 5.8S-ITS-2 haplotypes, with great genetic variability difference between both markers (0.9% vs 31.2%). Five cox1 haplotypes were shared with other countries, mainly Italy, USA and China, but none was shared between Europe and Brazil. The 5.8S-ITS-2 showed 2–7 intra-individual (mean 4.7) and 16–34 intra-/inter-population haplotypes (24.7), including haplotypes shared between Spain, France and Brazil. A 4.3% of ITS-2 haplotypes were shared, mainly with Italy, USA and Thailand, evidencing worldwide spread and introductions from areas where recent outbreaks of Ae. albopictus-transmitted pathogens occurred. Wing size showed sex differences. Wing shape distinguished between Brazilian and European specimens. Both genetic and morphometric markers showed differences between insular Spain and continental Spain, France and Brazil. Conclusions: ITS-2 proves to be a useful marker to assess Ae. albopictus spread, providing pronouncedly more information than cox1, including intra-individual, intra-population and inter-population levels, furnishing a complete overview of the evolutionary exchanges followed by this mosquito. Wing morphometry proves to be a useful phenotyping marker, allowing to distinguish different populations at the level of both male and female specimens. Results indicate the need for periodic surveillance monitorings to verify that no Ae. albopictus with high virus transmission capacity is introduced into Europe. Graphic Abstract: [Figure not available: see fulltext.] © 2021, The Author(s)

Desenvolvimento de Um Sistema Web Para Gestão de Simulações Dosimétricas Para Radiodiagnóstico / Development of a Web System to Manage Dosimetric Simulations for Radiodiagnosis

Este trabalho descreve a implementação de uma plataforma Web de forma automatizada para a criação, gestão, acompanhamento e análise de simulações dosimetricas para Radiodiagnóstico. Utilizando o codigo GATE/Geant4 baseado em Monte Carlo o sistema realiza simulações computacionais de exames médicos envolvendo raios-X. A estrutura da plataforma permeteu uma redução do tempo de geração e processamento das simulações. O sistema proporsiona no final as dosis aos quais os pacientes são submetidos em radiodiagnóstico, magnitude necesaria para a evaluação do risco de câncer radioinduzido com exames que utilizam raios-X