International Symposium on Physics, 2020
43
2020
2,376
3 hours 35 minutes
Results 1-36 out of 43
04:54
80Oliveira, Ana Rafaely M. deIn this project we discuss the main aspects and results of the phenomenological model MOND (MOdified Newtonian Dynamics). The MOND proposal is based on the modification of Newton's second law, delimiting two acceleration regimes. Thus, we were able to explain in good approximation the phenomenon of mass discrepancy, seen in Weak Gravitational Lenses and in the RotationAl Speed Curve in Spiral Galaxies. To verify the success of the model, we developed a Program with the objective of collecting, organizing and plotting the speed data of the 175 galaxies of the Online Repository SPARC. Using these data, the parameters of the theoretical curves were adjusted by linear regression, allowing to verify the correct functioning of the program, as well as the determination of the value of critical acceleration $a_0$ that delimits the two dynamic regimes of the MOND model.
2020Unidade Acadêmica de Física (UAF) et al.
05:33
53Flores, Efracio Mamani et al.2020Unidade Acadêmica de Física (UAF) et al.
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26Silva Avelino, Lineker Matheus2020Unidade Acadêmica de Física (UAF) et al.
02:00
28Bhattacharjee, Snehasish2020Unidade Acadêmica de Física (UAF) et al.
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82Candido, Deivyson Anderson Silva2020Unidade Acadêmica de Física (UAF) et al.
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70Carvalho, Bruno Rego de2020Unidade Acadêmica de Física (UAF) et al.
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16Li, LingfengInformation deformation and loss in jet clustering are one of the major limitations for precisely measuring hadronic events at future ee colliders. Because of their dominance in data, the measurements of such events are crucial for advancing the precision frontier of Higgs and electroweak physics in the next decades. We show that this difficulty can be well-addressed by synergizing the event-level information into the data analysis, with the techniques of deep neutral network. In relation to this, we introduce a CMB-like observable scheme, where the event-level kinematics is encoded as Fox-Wolfram (FW) moments at leading order and multi-spectra at higher orders. Then we develop a series of jet-level (w/ and w/o the FW moments) and event-level classifiers, and analyze their sensitivity performance comparatively with two-jet and four-jet events. As an application, we analyze measuring Higgs decay width at ee colliders with the data of 5ab^-1 @ 240GeV. The precision obtained is significantly better than the baseline ones presented in documents. We expect this strategy to be applied to many other hadronic-event measurements at future ee colliders, and to open a new angle for evaluating their physics capability.
2020Unidade Acadêmica de Física (UAF) et al.
04:36
81Santos, WillianWith the discovery of graphene in 2004, a new line of research in two-dimensional materials was unveiled. As this innovation we find the transition metal dichalcogenides (TMD) materials that became known as last generation graphene since these systems have many degrees of freedom to be explored and understood. We can find the TMD in three different phases, which depends on the number of electrons in the d orbital of the transition metals and the size of the atoms. Usually these materials are found in three polymorphs schematized in 1T, 2H and 3R, where the number represents the number of layers of the unit cell and the characters indicate the trigonal, hexagonal and rhombohedral symmetry, however according to some crystalline systems of these new materials of the TMDC type that we only find in the cubic phase. In this work, we use first principle calculations, based on the Density Functional Theory (DFT), using the generalized gradient (GGA) and local density (LDA) approximations and the PBE and CAPZ functional, used in optimizations and property descriptions structural, electronic and optical, implemented in the computer code CASTEP, to investigate the optical electronic properties of transition metal dichhalcogenides (TMD). The present work consists of the study of materials with the following formation $ RuX_2 $ com (X = S, Se é Te). As a result, it was seen that the polymorphic systems of the type $ RuX_2 $ their phase is extremely cubic, through the theoretical models of the theory of bands we noticed that the polymorphs have semiconductor characteristics of indirect gap. With the results of the optical properties we calculated $ \ epsilon_ {0} $ for all structures of the type $ RuX_2 $ using the functional GGA-PBE and LDA-CAPZ
2020Unidade Acadêmica de Física (UAF) et al.
04:40
212Figueiredo, LucasThe classical and quantum systems are many times seen as disconnected areas of physics and with totally distinct mathematical methods. This is not entirely true, many methods of the classical mechanics are very near to those used in the bases of quantum mechanics as the Poisson brackets, the Hamilton-Jacobi equation and the path integral formalism. In this presentation we will show an interplay between the classical and the quantum world in the path integral formalism. In the classical theory the path integral formalism is useful to describe the brownian motion, a kind of stochastic process in which positions are randomic variables varying according a parameter, the time; these positions are described by a distribution probability. This type of motion is observed, for exemple, in very small particles suspended on a fluid. In order to determine this distribution probability we can use the diffusion equation used by Einstein in his 1906 article about the brownian motion or use the Jaynes principle, a powerful tool of information theory to obtain probability distributions subjected to constraints. With the knowledge of the position distribution we are able to construct the path probability: we consider that the next step of a brownian particle is independent of the previous steps performed (markovian property), due to this property we can associate successive position probabilities and then obtain the Wiener path integral. This path integral gives the probability of a particle describe a given trajectory. An specific use of the Wiener integral is to treat the brownian movement with absorption and in this case is possible to show that the Wiener path integral satisfies the Feynman-Kac formula, a equation that establishes a connection between the stochastic processes theory and the differential equation theory. Modifying the Feynman-Kac formula to the Schrödinger equation we estabilish a map to modify the Wiener path integral and thus obtain the Feynman path integral to quantum mechanics.
2020Unidade Acadêmica de Física (UAF) et al.
04:14
61Gomes Vieira, José Augusto2020Unidade Acadêmica de Física (UAF) et al.
05:04
69Freitas, Helena RabeloThrough the science known as Myconanotechnology, it is possible to use fungi to carry out the green synthesis of nanoparticles, an economically viable and eco-friendly alternative to obtain nanomaterials. Quantum dots (QDs) are great examples that can resultfrom this process. Such elements are semiconductor nanoparticles confined in the three spatial dimensions, which possess optical and electronical properties strictly related to their size. Thus, this research aims to use five species of edible fungi to perform the green synthesis of type II-IV CdS quantum dots with the capacity of absorbing and emitting light. The edible fungi Pleurotus ostreatus, Pleurotus sp., Coprinus comatus, Coprinussp.and Agaricus subrufescens used in this study were obtained from the culture collection of fungi of the Agricultural Microbiology laboratory from the Federal University of Lavras (UFLA), Brazil. The cultivation was carried out in 250mL Erlenmeyer flasks containing 100mL of sterile potato dextrose broth (PBD). Five discs of mycelium from each fungal species were placed into the individual flasks. Hence, the mycelia were cultured superficially in a shaker at 27◦C for 10 days. Then, the mycelia were filtered and washed in ultrapure water for 10 times so as to eliminate the residual culture medium. Hereafter, 50mL of ultrapure water was added to the mycelia, which were incubated for 4 days at 27◦C. In order to produce CdS QDs, solutions of CdSO4and Na2S were added to the flasks containing fungal mycelia, which then presented photoluminescent properties under UV light, which can be interpreted as a qualitative indicator of the presence of nanoparticles. Samples from each flask were extracted, centrifuged and the supernatants were dilluted in ultrapure water. A solution without adding cadmium sulfate and sodium sulphide was used as a control. The ultraviolet-visible (UV-Vis) absorbtion spectra ofthe CdS quantum dots will be measured, and the luminescence spectra analysis will be carried out so as to evaluate the size range of the nanoparticles produced.
2020Unidade Acadêmica de Física (UAF) et al.
04:51
56Freire Pereira, Joseane et al.2020Unidade Acadêmica de Física (UAF) et al.
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35César, Rafael Sousa2020Unidade Acadêmica de Física (UAF) et al.
05:17
36Mandal, SanjayA complete theory of gravity impels us to go beyond Einstein's General Relativity. One promising approach lies in a new class of teleparallel theory of gravity named f (Q), where the nonmetricity Q is responsible for the gravitational interaction. The important roles any of these alternative theories should obey are the energy condition constraints. Such constraints establish the compatibility of a given theory with the causal and geodesic structure of space-time. In this work, we present a complete test of energy conditions for f (Q) gravity models. The energy conditions allowed us to fix our free parameters, restricting the families of f (Q) models compatible with the accelerated expansion our Universe passes through. Our results straight the viability of f (Q) theory, leading us close to the dawn of a complete theory for gravitation.
2020Unidade Acadêmica de Física (UAF) et al.
03:35
40Brhian, Alysson de Souza Muniz Silva et al.Communications using radio waves based on the GNSS (Global Navigation Satellite System) depend on the spatio-temporal behavior of the ionospheric layer, which is exposed to disturbances that produce distortion of the microwave signals used in satellite technologies. One of the factors that produces these disturbances in the ionosphere are gravity waves, caused by perturbations in the lower atmosphere resulting from topographic and climatic factors. Despite its importance for airworthiness, there are still no technologies to correct or anticipate the effects of these ionospheric instabilities. The objective of this work is to study the formation of gravity waves from meteorological quantities, such as pressure, wind speed, kinetic energy, and potential energy, obtained from all aerodromes in the Brazilian sector. It is worth mentioning that this is the first study that analyzes data from all aerodromes where radiosondeings are routinely performed. We present an extensive and detailed statistical analysis of the time series of measures and quantities related to gravity waves, obtaining a general scenario of its temporal and spatial behavior covering the entire national territory.
2020Unidade Acadêmica de Física (UAF) et al.
05:03
56Sousa, Mylena Mayla de et al.2020Unidade Acadêmica de Física (UAF) et al.
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43Arizilanio, Jonatas da Silva et al.2020Unidade Acadêmica de Física (UAF) et al.
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40Silva, Jonas Jorge D. Pinheiro daWe describe how the deformation matrix $\Omega ^{\mu}_{\nu}$, which relates the sources of matter associated with the metric $g_{\mu\nu}$ and the metric $q_{\mu\nu}$, provides an alternative description for the Einstein tensor, relating it to the energy-moment tensor $\tilde{T}^{\mu}_{\nu}(q) $. We will use gravity $f(R)$ to establish the general mapping equations for scalar fields.
2020Unidade Acadêmica de Física (UAF) et al.
05:48
36Azevedo, Helymarckson Batista deThe search for new materials has aroused the increasing interest of researchers from different areas, especially if such materials enable the development of smaller and more efficient devices than others already on the market. Among the main types of materials sought are those that can be obtained in two-dimensional (2D) form, due to the successful discovery of graphene, which is a 2D material with excellent electronic and mechanical properties, for example. A class of materials that can be obtained in 2D form and that has gained prominence in recent times is that of Transition Metal Dichalcogenides (TMDs). Some of these materials are already well known and several works have used calculations of first principles through the Density Functional Theory (DFT) to obtain properties of two-dimensional TMDs. The possibility of predicting properties (electronic and vibrational, for example) and the structure of TMDs through computer simulations is extremely advantageous, as it makes a previous experimental study of such materials unnecessary. Thus, in this work, a study will be carried out on two-dimensional materials, especially on TMDs and their characteristics. In addition, the DFT will be studied in order to describe how such a theory was built and on its computational implementation, which is what makes it possible to perform computer simulations of multi-electronic systems. Finally, a representation of the gains from studying materials such as transition metal dichalcogenides through the density functional theory will be shown.
2020Unidade Acadêmica de Física (UAF) et al.
04:56
48Nyassor, Prosper K. et al.2020Unidade Acadêmica de Física (UAF) et al.
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28Ferreira, Marcelo da Silva et al.2020Unidade Acadêmica de Física (UAF) et al.
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46Arora, SimranThe work presents the late-time cosmology in $f(Q, T)$ gravity, where dark energy is strictly geometric. We assume that the universe is governed by pressure-less matter that produces a scale factor $a(t)$. We begin by using a well-motivated gravity model $f(Q, T)= m Q^{n} + b T$, where m,n, and b are model parameters. Also, constraints on the model parameters from the revised 57 points of Hubble data sets and 580 points of union 2.1 compilation supernovae data sets are placed to investigate the model's cosmological viability. We have also thoroughly examined the existence of dark energy with the assistance of {s-r}, {q-r} diagnostic analysis. The present study makes it clear that gravity $f(Q, T)$ can be promising in resolving the existing cosmic acceleration and, thus, an acceptable solution to the issue of dark energy.
2020Unidade Acadêmica de Física (UAF) et al.
04:50
129Fortunato, JéfersonSince the discovery that the Universe is under accelerated expansion in the '90s, several attempts have been made to explain the mechanism that causes this expansion. In this research, we investigate cosmological models using the latest observational datasets - including 41 measurements of the Hubble parameter and the Pantheon sample - and how cosmological observations can be used to estimate the free parameters of these models. We perform cosmological parameter estimation over the ΛCDM and CDM flat models.
2020Unidade Acadêmica de Física (UAF) et al.
04:00
38Lima Júnior, José Grimário deGeneral Relativity, proposed by Einstein to describe gravitational phenomena, is a very well-tested theory at the solar system scale. However, in recent decades, new phenomena appeared, giving rise to several new alternative approaches both, on the particle content side, as well as on the gravitational physics one. In particular, the family of metric-affine theories of gravity based on the Ricci tensor (RBGs), formulated "a la Palatini'', can be put in correspondence with existing solutions in General Relativity, and vice versa. This fact makes it possible to use very consistent methods and results from the General Relativity context, to explore new results within the context of these class of metric-affine theories. This method has already been applied to several cases. In the present work we will explore the case of anisotropic fluids.
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05:49
48Oliveira, Rafael Camelo da Costa et al.2020Unidade Acadêmica de Física (UAF) et al.
04:26
33Ordonho, Renato Ferreira2020Unidade Acadêmica de Física (UAF) et al.
04:37
40Petruzziello, LucianoIn this talk, I study the non-relativistic limit of the Dirac equation for mixed neutrinos. A thorough analysis demonstrates that such a procedure inevitably leads to a redefinition of the inertial mass. This happens because, in contrast to the usual unmixed situations, the antiparticle sector contribution cannot be neglected. Furthermore, one can show that, when a gravitational interaction is switched on, in the weak-field approximation the mass parameter which couples to gravity (gravitational mass) does not undergo the same reformulation as the inertial mass; hence, the breakdown of the weak equivalence principle is unavoidable.
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06:00
34Girado Guzman, DiegoNeste trabalho estão sendo estudadas as biomoléculas presentes no Capsicum Annuum(pimentão) e os efeitos que os solventes provocam nelas. Os pimentões são frutos constituídopor um conjunto complexa de biomoléculas nas quais encontramos os carotenoides e asclorofilas, estes dois tipos de biomoléculas contribuem para que estes frutos apresentemdiferentes cores. O estudo e análise deste conjunto de biomoléculas estão sendo realizadasnas amostras in-natura e em preparação com solvente. Dentre a complexidades dascores dos pimentões foram escolhidos os pimentões nas cores: verde, amarelo, laranja evermelho. Neste sentido, estão sendo usado dois espectrômetros, UV- Visível convencionale Fotoacústico, que possibilitam obter informações dos estados eletrônicos das biomoléculas,com princípios de detecção diferente possibilitando resultados experimentais mais robustos.
2020Unidade Acadêmica de Física (UAF) et al.
04:09
164Santos, Jaiane da Silva2020Unidade Acadêmica de Física (UAF) et al.
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38Oliveira, Rubens Raimundo de Sousa et al.2020Unidade Acadêmica de Física (UAF) et al.
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42Cabrera Capera, EmilseIn this work, the contributions of the Left-Right symmetric model (LRSM) to the half-life of neutrinoless double beta decay (0νββ) were theoretically analyzed. The constraints in the parameter space associated with the new mechanisms ⟨λ⟩ and ⟨η⟩ were calculated according to four considered scenarios, given by the current and future experimental limits for 0νββ decay in Ge-76, Te-130 and Xe-130.
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42Mateus, Anderson E.One of the theories that has been taking shape in recent years, both in theoretical and experimental aspects, is the idea that Lorentz’s symmetry can be violated in the high energy regime, on the Planck scale. It seems that on this scale, the physics we know, based on the Standard Model and the Theory of Relativity, should be unified in a theory of quantum gravity. From this scenario, the possibility arises that the Lorentz symmetry, fundamental in Physics, may be broken on this scale of energy. Since the caliber symmetry breaking mechanism that occurs spontaneously and that explains, for example, mass creation in a boson theory, is known, it is possible that Lorentz symmetry can also be broken spontaneously . On the other hand, another phenomenon that generates discussions, but which is more accepted within the community is the possibility that particles that interact with a flutuating quantum field can perform a random movement similar to the observed by Robert Brown in the 19th century with pollen grains. This movement is sometimes called the quantum brownian motion (QBM). It has been shown that QBM can occur in a flat geometry or in a time dependent one. So, a good question to ask is what is the effect of Lorentz’s symmetry breaking for the quantum brownian motion performed by a point particle? in this work, we seek to answer these questions.
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32Guimarães, Matheus de Oliveira et al.Recently, several studies have been performed which uses UV-Visible (UV-Vis) spectroscopy to characterize molecules in organic compounds. The Vitex Gardneriana Schaeur, popularly known in Brazil as Jaramataia, is a tree that could be found in Brazil’s northeast and is considered a medicinal plant. In this work, we tried to characterize the Vitex Gardneriana Schauer leaf utilizing UV-Vis Spectroscopy and computational simulations with the Time Dependent Density Functional Theory (TDDFT) to identify some molecules in this sample. For this purpose, were utilized simple extraction methods with distinct solvents, producing solutions that were used to perform the experimental measures of UV-Vis Spectroscopy. The UV-Vis spectrum results in absorption bands which indicate what molecules are presents in the sample. The TDDFT is able to simulate these bands for different molecules by calculate the energies and the electronic transitions. Comparing these simulations with the experimental data, it was possible to identify which molecules are contributing to form the experimental spectrum obtained. The preliminary results showed that is possible to extract biofunctional molecules with simple extraction methods and characterize them by UV-Vis Spectroscopy and TDDFT. In comparison to others methods more expensive founded in literacture that were used to this sample, like High Performance Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR), the methods utilized in this work presented good performance and results.
2020Unidade Acadêmica de Física (UAF) et al.
05:23
125Rufino da Silva, Carlos Eduardo et al.The spectroscopic study of biomolecules in fruit and vegetables was increasingly attracting the interest of scientists around the world. Our work aims to use photoacoustic spectroscopy as a tool for studying biomolecules and optical characterization of organic materials in view of their ability to probe materials without the primary need to perform an extraction procedure. To this end, new computational systems and methods have been developed that allowed the execution, hardware automation, acquisition of data from the experiment and a better interpretation of them. The samples of interest were characterized by photoacoustic spectroscopy, and the results going to be analyzed using the second derivative method and the phase method. As future perspectives, the thermal properties of these materials going to be studied.
2020Unidade Acadêmica de Física (UAF) et al.
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40Coelho, Johnathon Nunes2020Unidade Acadêmica de Física (UAF) et al.
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74Batista, Erikarlos David2020Unidade Acadêmica de Física (UAF) et al.