Bouncing cosmology in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e22" altimg="si3.svg"><mml:mrow><mml:mi>f</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi>R</mml:mi><mml:mo>,</mml:mo><mml:mi mathvariant="script">G</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math> gravity by order reduction

Barros, Bruno J.; Teixeira, Elsa M.; Vernieri, Daniele

doi:10.1016/j.aop.2020.168231

Cited by 17 publications

(19 citation statements)

References 21 publications

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“…The same approach has been adopted, e.g., in Refs. [50][51][52], where the authors find the form of the actions in agreement with the Big Bounce theory. In order to develop Quantum Cosmology in f (Q) gravity, we take into account the Arnowitt-Deser-Misner (ADM) formalism in modified STEGR action.…”

Section: Introductionsupporting

confidence: 61%

Bouncing cosmology in f(Q) symmetric teleparallel gravity

2020

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We consider f(Q) extended symmetric teleparallel cosmologies, where Q is the non-metricity scalar, and constrain its functional form through the order reduction method. By using this technique, we are able to reduce and integrate the field equations and thus to select the corresponding models giving rise to bouncing cosmology. The selected Lagrangian is then used to develop the Hamiltonian formalism and to obtain the Wave Function of the Universe which suggests that classical observable universes can be recovered according to the Hartle Criterion.

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Section: Introductionsupporting

confidence: 61%

Bouncing cosmology in f(Q) symmetric teleparallel gravity

2020

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“…(3.10) Thus, following Refs. [16][17][18], we assume spatial flatness of the spacetime (k = 0), and noticing that does not contribute to Eq. (1.1), we set = 0.…”

Section: Modified Friedmann Equation and Bouncing Cosmologymentioning

confidence: 99%

“…To achieve our goal, we follow closely the analysis outlined in Refs. [16][17][18][19][20], which is based on a reduction technique of the order of the differential equations [21][22][23]. This approach will allow us to obtain solutions which are perturbatively close to GR.…”

Section: Introductionmentioning

confidence: 99%

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Effective actions for loop quantum cosmology in fourth-order gravity

2021

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Loop quantum cosmology (LQC) is a theory which renders the Big Bang initial singularity into a quantum bounce, by means of short-range repulsive quantum effects at the Planck scale. In this work, we are interested in reproducing the effective Friedmann equation of LQC, by considering a generic f(R, P, Q) theory of gravity, where $$R=g^{\mu \nu }R_{\mu \nu }$$ R = g μ ν R μ ν is the Ricci scalar, $$P=R_{\mu \nu }R^{\mu \nu }$$ P = R μ ν R μ ν , and $$Q=R_{\alpha \beta \mu \nu }R^{\alpha \beta \mu \nu }$$ Q = R α β μ ν R α β μ ν is the Kretschmann scalar. An order reduction technique allows us to work in f(R, P, Q) theories which are perturbatively close to General Relativity, and to deduce a modified Friedmann equation in the reduced theory. Requiring that the modified Friedmann equation mimics the effective Friedmann equation of LQC, we are able to derive several functional forms of f(R, P, Q). We discuss the necessary conditions to obtain viable bouncing cosmologies for the proposed effective actions of f(R, P, Q) theory of gravity.

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“…A concentração deste contaminante varia com a característica química dos resíduos e com as condições ambientais de umidade, temperatura e pH do meio. 5 O aproveitamento do subproduto produzido pela agroindústria de pescado se justifica pelo valor nutricional e o potencial econômico que esse material apresenta. Os resíduos de pescado constituemse de proteínas com alto grau de hidrólise, apresentando maior digestibilidade em relação às proteínas musculares dos mamíferos e perfil de aminoácidos balanceados.…”

Section: Introductionunclassified

Acid Silage of Filleting Residue Two Fish Species Amazon for Use in Animal Feed

2020

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The study aimed to process and characterize acid silage from the residues of two species of Amazonian fish, piramutaba (Brachyplatystoma vaillantii) and dourada (Brachyplatystoma rousseauxii), in four storage times, with a view to use in animal feed. The research was developed at the Food Laboratory of the Center for Nature Science and Technology (CCNT) at the State University of Pará (UEPA). The physical-chemical analyzes (moisture, ash, proteins and lipids) of the wet silages and defatted flours were performed in triplicate considering four storage times: after the addition of acid (T0), on the seventh day of silage (T7), in the fifteenth day (T15) and on the twentieth day (T20). The data were submitted to analysis of variance (ANOVA) and the means compared by Tukey's method (α = 0.05). On the 7th day, the pH stabilized at 4.3 for the two silages. During the experimental period, the temperature in the dourada silage varied between 25.5 and 28.0 ºC, and in the piramutaba silage between 25.0 and 28.0 ºC. The lowest humidity values for the silage of bream and piramutaba were 75.69% (7th day) and 73.66% (15th day), respectively. Higher ash values were observed, on the 20th experimental day, for dourada (4.15%) and piramutaba (3.77%). The dourada silage, on the 7th day, showed a higher average protein value (13.10%), and the piramutaba, on the 15th day, with a value of 12.86%. The flours of dourada and piramutaba presented protein values of 66.78% and 66.64% and lipids of 6.85% and 9.05%, respectively. The defatted piramutaba flour showed higher values (1.75%) of lipids compared to the golden flour (1.11%). Therefore, the use of dourada and piramutaba residues showed excellent nutritional potential for use in animal feed, with an excellent level of protein and low values of humidity and lipids.

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Bouncing cosmology in f(R,G) gravity by order reduction

Cited by 17 publications

References 21 publications

Bouncing cosmology in f(Q) symmetric teleparallel gravity

Bouncing cosmology in f(Q) symmetric teleparallel gravity

Effective actions for loop quantum cosmology in fourth-order gravity

Acid Silage of Filleting Residue Two Fish Species Amazon for Use in Animal Feed

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