13,755 research outputs found
Bouncing Eddington-inspired Born-Infeld cosmologies: an alternative to Inflation ?
We study the dynamics of a homogeneous and isotropic
Friedmann-Robertson-Walker universe in the context of the Eddington-inspired
Born-Infeld theory of gravity. We generalize earlier results, obtained in the
context of a radiation dominated universe, to account for the evolution of a
universe permeated by a perfect fluid with an arbitrary equation of state
parameter . We show that a bounce may occur for , if is
time-dependent, and we demonstrate that it is free from tensor singularities.
We argue that Eddington-inspired Born-Infeld cosmologies may be a viable
alternative to the inflationary paradigm as a solution to fundamental problems
of the standard cosmological model.Comment: 4 pages, 1 figur
Recommended from our members
A guide to research with care homes
Purpose - A growing older population with complex care needs, including dementia, are living in care homes. It is important to support researchers in conducting ethical and appropriate work in this complex research environment. The purpose of this paper is to discuss key issues in care homes research including examples of best practice. The intention is to inform researchers across disciplines, leading to more sensitive and meaningful care home research practice.
Design/methodology/approach - Experienced care homes researchers were invited to provide methodological insights and details not already reported in their publications. These have been analysed, creating key themes and linked to project publications.
Findings - The need for reflexivity was a key finding. In particular, researchers need to: appreciate that the work is complex; see participants as potential research partners; and consider how cognitive and physical frailty of residents, staffing pressures and the unique environments of care homes might impact upon their research. Other challenges include recruitment and consenting people who lack mental capacity.
Research limitations/implications - As the care homes research landscape continues to develop and grow, there still remains limited reflection and discussion of methodological issues with a need for a "safe space" for researchers to discuss challenges.
Originality/value - This review is an updated methodological guide for care homes researchers, also highlighting current gaps in the mechanisms for continuing to share best research practice
Model-driven engineering techniques and tools for machine learning-enabled IoT applications: A scoping review
This paper reviews the literature on model-driven engineering (MDE) tools and languages for the internet of things (IoT). Due to the abundance of big data in the IoT, data analytics and machine learning (DAML) techniques play a key role in providing smart IoT applications. In particular, since a significant portion of the IoT data is sequential time series data, such as sensor data, time series analysis techniques are required. Therefore, IoT modeling languages and tools are expected to support DAML methods, including time series analysis techniques, out of the box. In this paper, we study and classify prior work in the literature through the mentioned lens and following the scoping review approach. Hence, the key underlying research questions are what MDE approaches, tools, and languages have been proposed and which ones have supported DAML techniques at the modeling level and in the scope of smart IoT services.info:eu-repo/semantics/publishedVersio
Variabilidade espacial da distribuição da cobertura vegetal após colheita mecanizada da cana-de-açúcar.
O presente trabalho teve como objetivo avaliar a variabilidade espacial na distribuição da cobertura vegetal, no sistema de colheita mecanizada da cana-de-açúcar. O experimento foi conduzido na Fazenda Santa Clara, localizada em Lambari D?Oeste, MT, em uma área experimental de 9,75 ha, sob cultivo de cana-de-açúcar, demarcada em 70 pontos. Foram quantificadas a cobertura vegetal (kg.ha-1) e as brotações, as quais foram analisadas pela estatística descritiva e geoestatística. Os resultados mostraram que existe variabilidade espacial na distribuição da cobertura vegetal sobre o solo após a colheita mecanizada da cana-de-açúcar
Exactly Solvable Interacting Spin-Ice Vertex Model
A special family of solvable five-vertex model is introduced on a square
lattice. In addition to the usual nearest neighbor interactions, the vertices
defining the model also interact alongone of the diagonals of the lattice. Such
family of models includes in a special limit the standard six-vertex model. The
exact solution of these models gives the first application of the matrix
product ansatz introduced recently and applied successfully in the solution of
quantum chains. The phase diagram and the free energy of the models are
calculated in the thermodynamic limit. The models exhibit massless phases and
our analyticaland numerical analysis indicate that such phases are governed by
a conformal field theory with central charge and continuosly varying
critical exponents.Comment: 14 pages, 11 figure
SBR performance for synthetic and fishery wastewater treatment
The evaluation of a SBR performance treating synthetic and fishery wastewater was performed. Without salt addition, COD and ammonia removal rates over than 50% were obtained, indicating the occurrence of the first nitrification step and COD removal. With 0.5% salt, removal rates lower than 60% were attained, for ammonia removal efficiency probably due to ionic strength changes and cellular plasmolysis leading to inactivation of the nitrification organisms. The SBR performance was greater for synthetic wastewater, due to the inherent and controlled characteristics. For both, lower SVI were achieved as a valuable indicator towards the assessment of the aggregated biomass structure.National Council of Scientific and Technological Development of Brazil (CNPq); BIEURAM III ALFA co-operation project (European Commission)
Characterization of natural occurrence of Oenocarpus distichus in the state of Maranhão, Brazil.
In Maranhão States Amazon, bacaba stands out as an important resource to local populations. It is employed in human and animal feeding, building houses, traditional medicine and manufacturer goods. The economically viable part of this species is the processed pulp known as bacaba, sold in natura or frozen. Considering the great potential of sustainable economic exploitation of native fruit trees, such as the bacaba, occurrence areas of natural populations of O. distichus in three municipalities of the Gurupi micro region and two of the Chapada das Mangabeiras were mapped in order to subsidize future researches regarding conservation and use of the germplasm. Bacaba populations were mapped in cities of the two microregions: 1) Gurupi where soils, in general, are of low natural fertility with predominance of dystrophic plinthudults and red-yellow dystrophic and plinthic soils and; 2) Chapada das Mangabeiras, where yellow dystrophic hapludox soils are found; and in the escarpments the litholic dystrophic neosoils are common. In these micro regions, bacaba populations are reduced to individuals found in backyards
Euler-Lagrange equations for composition functionals in calculus of variations on time scales
In this paper we consider the problem of the calculus of variations for a
functional which is the composition of a certain scalar function with the
delta integral of a vector valued field , i.e., of the form
. Euler-Lagrange
equations, natural boundary conditions for such problems as well as a necessary
optimality condition for isoperimetric problems, on a general time scale, are
given. A number of corollaries are obtained, and several examples illustrating
the new results are discussed in detail.Comment: Submitted 10-May-2009 to Discrete and Continuous Dynamical Systems
(DCDS-B); revised 10-March-2010; accepted 04-July-201
- …