The gravitational S-matrix

We investigate the hypothesized existence of an S-matrix for gravity, and some of its expected general properties. We first discuss basic questions regarding existence of such a matrix, including those of infrared divergences and description of asymptotic states. Distinct scattering behavior occurs in the Born, eikonal, and strong gravity regimes, and we describe aspects of both the partial wave and momentum space amplitudes, and their analytic properties, from these regimes. Classically the strong gravity region would be dominated by formation of black holes, and we assume its unitary quantum dynamics is described by corresponding resonances. Masslessness limits some powerful methods and results that apply to massive theories, though a continuation path implying crossing symmetry plausibly still exists. Physical properties of gravity suggest nonpolynomial amplitudes, although crossing and causality constrain (with modest assumptions) this nonpolynomial behavior, particularly requiring a polynomial bound in complex s at fixed physical momentum transfer. We explore the hypothesis that such behavior corresponds to a nonlocality intrinsic to gravity, but consistent with unitarity, analyticity, crossing, and causality.Comment: 46 pages, 10 figure

Pade approximation of the S-matrix as a way of locating quantum resonances and bound states

It is shown that the spectral points (bound states and resonances) generated by a central potential of a single-channel problem, can be found using rational parametrization of the S-matrix. To achieve this, one only needs values of the S-matrix along the real positive energy axis. No calculations of the S-matrix at complex energies or a complex rotation are necessary. The proposed method is therefore universal in that it is applicable to any potential (local, non-local, discontinuous, etc.) provided that there is a way of obtaining the S-matrix (or scattering phase-shifts) at real collision energies. Besides this, combined with any method that extracts the phase-shifts from the scattering data, the proposed rational parametrization technique would be able to do the spectral analysis using the experimental data.Comment: 20 pages, 6 figure

Research on Long-Term Care Homes for Older People in Brazil: Protocol for Scoping Review

LOTUS CONSORTIUM - Improving care in Long-term Care Institutions in Brazil and Europe through Collaboration and ResearchBackground The fast growth of the ageing population in low and middle-income countries, such as Brazil, has allowed little time for social and health care systems to adapt. As the care needs for the most vulnerable and frail older people become increasingly complex, services and governments need to ensure that long term care homes deliver high-quality and evidence-based care to meet their healthcare needs. Aim To examine and map the range of research undertaken in Brazil regarding care homes published in peer reviewed journals. Method This scoping review will consider all relevant peer-reviewed primary studies fully or partly conducted in Brazilian care homes including those which consider workforce (for example, e.g. healthcare professionals, care staff, and management level staff) and care home residents (older people aged 60 years and above), using empirical and original research focused on any health related topic. The searches will be conducted using bibliographic databases (MEDLINE, EMBASE, LILACS and Google Scholar) and manual searching of the reference lists of relevant studies published in English, Portuguese or Spanish from inception up to 2018. Two authors will independently screen each document by title and abstract against the eligibility criteria. In case of disagreement, a third reviewer will be consulted. Data from the included studies will be extracted and reported using tables, graphs, and narrative accounts using elements of content analysis. The Mixed Methods Appraisal Tool will be used to appraise the methodological quality of the included studies

The Definition and Measurement of the Topological Entropy per Unit Volume in Parabolic PDE's

We define the topological entropy per unit volume in parabolic PDE's such as the complex Ginzburg-Landau equation, and show that it exists, and is bounded by the upper Hausdorff dimension times the maximal expansion rate. We then give a constructive implementation of a bound on the inertial range of such equations. Using this bound, we are able to propose a finite sampling algorithm which allows (in principle) to measure this entropy from experimental data.Comment: 26 pages, 1 small figur

Accelerating networks

Evolving out-of-equilibrium networks have been under intense scrutiny recently. In many real-world settings the number of links added per new node is not constant but depends on the time at which the node is introduced in the system. This simple idea gives rise to the concept of accelerating networks, for which we review an existing definition and -- after finding it somewhat constrictive -- offer a new definition. The new definition provided here views network acceleration as a time dependent property of a given system, as opposed to being a property of the specific algorithm applied to grow the network. The defnition also covers both unweighted and weighted networks. As time-stamped network data becomes increasingly available, the proposed measures may be easily carried out on empirical datasets. As a simple case study we apply the concepts to study the evolution of three different instances of Wikipedia, namely, those in English, German, and Japanese, and find that the networks undergo different acceleration regimes in their evolution.Comment: 12 pages, 8 figure

The gliding phase in swimming: the effect of water depth

Aiming to achieve higher performances, swimmers should maximize each component of swimming races. During starts and turns, the gliding phase represents a determinant part of these race components. Thus, the depth position allowing minimizing the hydrodynamic drag force represents an important concern in swimming research. The aim of this study was to analyse the effect of depth on drag during the underwater gliding, using computational fluid dynamic

Structural constraints in complex networks

We present a link rewiring mechanism to produce surrogates of a network where both the degree distribution and the rich--club connectivity are preserved. We consider three real networks, the AS--Internet, the protein interaction and the scientific collaboration. We show that for a given degree distribution, the rich--club connectivity is sensitive to the degree--degree correlation, and on the other hand the degree--degree correlation is constrained by the rich--club connectivity. In particular, in the case of the Internet, the assortative coefficient is always negative and a minor change in its value can reverse the network's rich--club structure completely; while fixing the degree distribution and the rich--club connectivity restricts the assortative coefficient to such a narrow range, that a reasonable model of the Internet can be produced by considering mainly the degree distribution and the rich--club connectivity. We also comment on the suitability of using the maximal random network as a null model to assess the rich--club connectivity in real networks.Comment: To appear in New Journal of Physics (www.njp.org

Efeito de diferentes populacoes de percevejos sobre o rendimento e seus componentes, caracteristicas agronomicas e qualidade de semente de soja.

No período de 1980 a 1984, foi conduzida, em Londrina, PR, uma serie de cinco experimentos, objetivando quantificar o efeito de diferentes populações de percevejos sobre o rendimento e seus componentes, as características agronômicas e a qualidade da semente de soja. A cultivar utilizada foi a UFV-1, por sua característica de ciclo longo, constando o experimento de seis tratamentos que previam a aplicação de endosulfan (525 g i.a./ha) quando a população de ninfas grandes e adultos de percevejos (Nezara viridula, Piezodorus guildinii e Euschistus heros) atingisse 1, 2, 4 ou 6 exemplares por metro de linha. Adicionalmente, havia um tratamento com aplicação de inseticida em caráter preventivo, de forma a impedir o surgimento de percevejos nestas parcelas, e um tratamento sem controle, permitindo o estabelecimento de uma população natural destes pentatomideos. As amostragens dos percevejos foram semanais, ou mais frequentes quando próximo ao pico populacional, através do método do pano, com cinco amostras por parcela. Os resultados indicaram não haver redução da produção com populações de ate quatro percevejos por metro, e deduzidos os custos de controle, qualquer população de percevejos propiciou uma produção liquida superior ao controle preventivo, assim como evidenciou não haver diferenças entre as populações de percevejos no tocante a produção liquida. Não foram constatados efeitos deleterios de importância sobre as características agronômicas, porem o aumento da população de percevejos conduziu a um menor numero de vagens, sementes e sementes por vagem, ao passo que o peso da semente não foi afetado. Ate o nível de quatro percevejos por metro, o poder germinativo da semente manteve-se acima de 80%, porem, neste nível, observou-se redução do vigor da semente. O ataque de percevejos provocou uma redução no teor de óleo e um aumento no teor de proteína sem, no entanto, afetar significativamente os componentes destas frações. Apos oito aplicações de endosulfan na dose de 525 g i.a./ha, não foram constatados resíduos acima do permitido pela legislação brasileira. Os resultados alcançados permitem concluir haver grande margem de segurança nas atuais recomendações do Programa de Manejo de Pragas, as quais se situam muito baixo das populações de percevejos que possam ocasionar queda de produção ou da qualidade da semente.bitstream/item/69810/1/Boletim-de-pesquisa-1.pd