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

Distributed formation control of multiple unmanned aerial vehicles over time-varying graphs using population games

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a control technique based on distributed population dynamics under time-varying communication graphs for a multi-agent system structured in a leader-follower fashion. Here, the leader agent follows a particular trajectory and the follower agents should track it in a certain organized formation manner. The tracking of the leader can be performed in the position coordinates x; y; and z, and in the yaw angle phi. Additional features are performed with this method: each agent has only partial knowledge of the position of other agents and not necessarily all agents should communicate to the leader. Moreover, it is possible to integrate a new agent into the formation (or for an agent to leave the formation task) in a dynamical manner. In addition, the formation configuration can be changed along the time, and the distributed population-games-based controller achieves the new organization goal accommodating conveniently the information-sharing graph in function of the communication range capabilities of each UAV. Finally, several simulations are presented to illustrate different scenarios, e.g., formation with time-varying communication network, and time-varying formationPeer ReviewedPostprint (author's final draft

Fighting bisphenol a-induced male infertility: The power of antioxidants

Bisphenol A (BPA), a well-known endocrine disruptor present in epoxy resins and poly-carbonate plastics, negatively disturbs the male reproductive system affecting male fertility. In vivo studies showed that BPA exposure has deleterious effects on spermatogenesis by disturbing the hypothalamic–pituitary–gonadal axis and inducing oxidative stress in testis. This compound seems to disrupt hormone signalling even at low concentrations, modifying the levels of inhibin B, oestradiol, and testosterone. The adverse effects on seminal parameters are mainly supported by studies based on urinary BPA concentration, showing a negative association between BPA levels and sperm concentration, motility, and sperm DNA damage. Recent studies explored potential approaches to treat or prevent BPA-induced testicular toxicity and male infertility. Since the effect of BPA on testicular cells and spermatozoa is associated with an increased production of reactive oxygen species, most of the pharmacological approaches are based on the use of natural or synthetic antioxidants. In this review, we briefly describe the effects of BPA on male reproductive health and discuss the use of antioxidants to prevent or revert the BPA-induced toxicity and infertility in men.This research was funded by Institute for Biomedicine—iBiMED, grant number UID/BIM/04501/2020 and by individual grant from FCT of the Portuguese Ministry of Science and Higher Education to J.S. (SFRH/BD/136896/2018)

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

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

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

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

The unexplored virome of two Atlantic coast fish: contribution of next-generation sequencing to fish virology

Much of the knowledge on viruses is focused on those that can be propagated using cell-cultures or that can cause disease in humans or in economically important animals and plants. However, this only reflects a small portion of the virosphere. Therefore, in this study, we explore by targeted next-generation sequencing, how the virome varies between Atlantic horse mackerels and gilthead seabreams from fisheries and aquaculture from the center and south regions of Portugal. Viral genomes potentially pathogenic to fish and crustaceans, as well as to humans, were identified namely Astroviridae, Nodaviridae, Hepadnaviridae, Birnaviridae, Caliciviridae, and Picornaviridae families. Also bacteriophages sequences were identified corresponding to the majority of sequences detected, with Myoviridae, Podoviridae, and Siphoviridae, the most widespread families in both fish species. However, these findings can also be due to the presence of bacteria in fish tissues, or even to contamination. Overall, seabreams harbored viruses from a smaller number of families in comparison with mackerels. Therefore, the obtained data show that fish sold for consumption can harbor a high diversity of viruses, many of which are unknown, reflecting the overall uncharacterized virome of fish. While cross-species transmission of bonafide fish viruses to humans is unlikely, the finding of human pathogenic viruses in fish suggest that fish virome can be a potential threat regarding food safety

Unveiling Viruses Associated with Gastroenteritis Using a Metagenomics Approach

Acute infectious gastroenteritis is an important illness worldwide, especially on children, with viruses accounting for approximately 70% of the acute cases. A high number of these cases have an unknown etiological agent and the rise of next generation sequencing technologies has opened new opportunities for viral pathogen detection and discovery. Viral metagenomics in routine clinical settings has the potential to identify unexpected or novel variants of viral pathogens that cause gastroenteritis. In this study, 124 samples from acute gastroenteritis patients from 2012-2014 previously tested negative for common gastroenteritis pathogens were pooled by age and analyzed by next generation sequencing (NGS) to elucidate unidentified viral infections. The most abundant sequences detected potentially associated to acute gastroenteritis were from Astroviridae and Caliciviridae families, with the detection of norovirus GIV and sapoviruses. Lower number of contigs associated to rotaviruses were detected. As expected, other viruses that may be associated to gastroenteritis but also produce persistent infections in the gut were identified including several Picornaviridae members (EV, parechoviruses, cardioviruses) and adenoviruses. According to the sequencing data, astroviruses, sapoviruses and NoV GIV should be added to the list of viral pathogens screened in routine clinical analysis