Interacting shells in AdS spacetime and chaos

We study the simplest two-body problem in asymptotically anti-de Sitter spacetime: two, infinitely thin, concentric spherical shells of matter. We include only gravitational interaction between the two shells, but we show that the dynamics of this system is highly nontrivial. We observe prompt collapse to a black hole, delayed collapse and even perpetual oscillatory motion, depending on the initial location of the shells (or their energy content). The system exhibits critical behavior, and we show strong hints that it is also chaotic

Híbridos comerciais de milho tolerantes ao déficit hídrico.

A deficiência hídrica é uma das principais causas da redução da produtividade de grãos em cultivos de milho sob sequeiro. Nesse contexto, este trabalho teve como objetivo identificar híbridos comerciais de milho que apresentem tolerância ao déficit hídrico

Implications of climate change to the design of protected areas : The case study of small islands (Azores)

Climate change is causing shifts in species distributions worldwide. Understanding how species distributions will change with future climate change is thus critical for conservation planning. Impacts on oceanic islands are potentially major given the disproportionate number of endemic species and the consequent risk that local extinctions might become global ones. In this study, we use species climate envelope models to evaluate the current and future potential distributions of Azorean endemic species of bryophytes, vascular plants, and arthropods on the Islands of Terceira and Sao Miguel in the Azores archipelago (Macaronesia). We examined projections of climate change effects on the future distributions of species with particular focus on the current protected areas. We then used spatial planning optimization software (PRION) to evaluate the effectiveness of protected areas at preserving species both in the present and future. We found that contractions of species distributions in protected areas are more likely in the largest and most populated island of Sao Miguel, moving from the coastal areas towards inland where the current protected areas are insufficient and inadequate to tackle species distribution shifts. There will be the need for a revision of the current protected areas in Sao Miguel to allow the sustainable conservation of most species, while in Terceira Island the current protected areas appear to be sufficient. Our study demonstrates the importance of these tools for informing long-term climate change adaptation planning for small islands.Peer reviewe

Comparison between Conventional Load Flow, QSTS Simulation, and Dynamic Simulation to Assess the Operation of Step Voltage Regulators in Active Distribution Networks

The assessment of step voltage regulator (SVR) operation in active distribution networks requires computational analysis tools capable of tackling the emerging technical challenges. Conventional load flow (CLF), quasi-static time series (QSTS) and dynamic simulations are typically employed to investigate high-penetration distributed generation (DG) interconnection impacts. Regarding the SVR runaway condition phenomenon, however, a consensus has yet to be reached on the most cost-effective simulation technique for capturing and reproducing the correct sequence of events. This work presents a comparative study of the CLF, QSTS and dynamic simulation techniques through modelling and analysis of two SVR-controlled test-feeders, in order to evaluate each approach performance in addressing scenarios of DG-caused reverse active power flow. Detailed descriptions of feeder voltage profile and SVR tap operations are provided to facilitate understanding of the mechanisms that characterize SVR runaway condition, as well as the advantages and drawbacks of each of the studied simulation techniques.Comment: 8 pages, 12 figures, submitted to XVIII ERIAC 201

Neural response telemetry measures in patients implanted with Nucleus 24®

Cochlear implantation has been recommended for children under 24 months of age. The use of objective measures is needed to help speech processor programming. The electrically evoked compound potential (EAP), which can be assessed by neural response telemetry (NRT), is one of those objective measures. AIM: to determine how often the EAP can be recorded by NRT system during surgery and to describe the responses. STUDY DESIGN: clinical with transversal cohort. MATERIAL AND METHOD: the impedances and NRT were measured in a group of 17 Nucleus 24 ® implant users. The responses were analyzed and compared to the etiology, hearing loss duration and electrode array position. RESULTS: The EAP was easily recorded in the apical electrodes and, in otosclerosis and meningitis cases the EAP threshold was higher than in the other etiology cases. CONCLUSIONS: The NRT can be found in 82% of the cases during surgery. The responses obtained may vary according to etiology and the position of electrodes along the cochlea.A possibilidade de realizar o implante coclear em crianças pequenas torna necessário o uso de medidas objetivas para auxiliar a programação do processador de fala. Telemetria é a propriedade que permite, no Nucleus 24®, a obtenção do potencial de ação composto evocado do VIII par (EAP) utilizando o implante como instrumento de estimulação e gravação para o estudo das propriedades neurais remanescentes. OBJETIVO: Descrever a utilização do sistema de telemetria para a gravação do EAP, caracterizando as respostas obtidas e a sua prevalência na condição intraoperatória. FORMA DE ESTUDO: clínico com coorte transversal. MATERIAL E MÉTODO: Medidas das impedâncias dos eletrodos e do EAP em um grupo de 17 indivíduos usuários do implante Nucleus 24® durante a cirurgia. Análise das respostas de acordo com a etiologia, o tempo de duração da surdez e a posição dos eletrodos dentro da cóclea. RESULTADOS: Maior prevalência nos eletrodos apicais e limiares mais elevados nos casos de meningite e otosclerose. CONCLUSÃO: A telemetria é eficiente para a verificação da integridade dos eletrodos na condição intraoperatória e para a gravação do EAP, apresentando alta prevalência na população estudada.HC-FMUSP Santa Casa de Misericórdia de SPHC-FMUSPUNIFESPPUC-SPUNIFESPSciEL

Avaliação genômica de touros Hereford e Braford.

Seleção genômica; Metodologia unificada para predizer os valores genéticos genômicos; Características apresentadas neste sumário; Como interpretar o sumário; Tabela de touros Braford; Tabela de touros Hereford; Estâncias que participaram do presente trabalho; Equipe participante do projeto.bitstream/item/81082/1/Dt-127.pd

The stochastic gravitational-wave background in the absence of horizons

Gravitational-wave astronomy has the potential to explore one of the deepest and most puzzling aspects of Einstein's theory: the existence of black holes. A plethora of ultracompact, horizonless objects have been proposed to arise in models inspired by quantum gravity. These objects may solve Hawking's information-loss paradox and the singularity problem associated with black holes, while mimicking almost all of their classical properties. They are, however, generically unstable on relatively short timescales. Here, we show that this 'ergoregion instability' leads to a strong stochastic background of gravitational waves, at a level detectable by current and future gravitational-wave detectors. The absence of such background in the first observation run of Advanced LIGO already imposes the most stringent limits to date on black-hole alternatives, showing that certain models of 'quantum-dressed' stellar black holes can be at most a small percentage of the total population. The future LISA mission will allow for similar constraints on supermassive black-hole mimickers

Constraining the mass of dark photons and axion-like particles through black-hole superradiance

Ultralight bosons and axion-like particles appear naturally in different scenarios and could solve some long-standing puzzles. Their detection is challenging, and all direct methods hinge on unknown couplings to the Standard Model of particle physics. However, the universal coupling to gravity provides model-independent signatures for these fields. We explore here the superradiant instability of spinning black holes triggered in the presence of such fields. The instability taps angular momentum from and limits the maximum spin of astrophysical black holes. We compute, for the first time, the spectrum of the most unstable modes of a massive vector (Proca) field for generic black-hole spin and Proca mass. The observed stability of the inner disk of stellar-mass black holes can be used to derive \emph{direct} constraints on the mass of dark photons in the mass range $10^{-13}\,{\rm eV}\lesssim m_V \lesssim 3\times 10^{-12}\,{\rm eV}$. By including also higher azimuthal modes, similar constraints apply to axion-like particles in the mass range $6\times10^{-13}\,{\rm eV}\lesssim m_{\rm ALP} \lesssim 10^{-11}\, {\rm eV}$. Likewise, mass and spin distributions of supermassive BHs --~as measured through continuum fitting, K$\alpha$ iron line, or with the future space-based gravitational-wave detector LISA~-- imply indirect bounds in the mass range approximately $10^{-19}\,{\rm eV}\lesssim m_V, m_{\rm ALP} \lesssim 10^{-13}\, {\rm eV}$, for both axion-like particles and dark photons. Overall, superradiance allows to explore a region of approximately $8$ orders of magnitude in the mass of ultralight bosons

Predição da resistência genética ao carrapato de bovinos Braford e Hereford a partir de um painel denso de marcadores moleculares.

O problema do carrapato bovino; A alternativa da seleção genômica; Resultados experimentais; Procedimentos para aplicação prática; Considerações finais.bitstream/item/77131/1/CT41.pd

Avaliação genômica para características de adaptação e caracterização racial de touros Hereford e Braford: edição 2016.

Seleção Genômica; Modelo Limiar; Metodologia Unificada para Predizer os Valores Genômicos; Características Avaliada; Como interpretar o sumário; Tabela de Touros Braford; Tabela de Touros Hereford; Fazendas que participaram do presente trabalhobitstream/item/149298/1/DOCUMENTO-151-online.pd