cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14325867.v1
title: Why is the sky dark at night? Geometric considerations with a historical and pedagogical look at the Olbers paradox

description: We present the Olbers paradox and some proposals for its solutions with geometric arguments based on simple cosmological and astrophysical models. A little-known sky splendor calculation shows that the Universe expansion to the night darkness is responsible for little more than half of the effect; the remainder comes from the low distribution of stars (and galaxies) that shine during a finite time in the Universe. High school or undergraduate teachers can explore this subject in an instigating, interdisciplinary, and historical way.
DOI: 10.6084/m9.figshare.14325867
title: Why is the sky dark at night? Geometric considerations with a historical and pedagogical look at the Olbers paradox

description: We present the Olbers paradox and some proposals for its solutions with geometric arguments based on simple cosmological and astrophysical models. A little-known sky splendor calculation shows that the Universe expansion to the night darkness is responsible for little more than half of the effect; the remainder comes from the low distribution of stars (and galaxies) that shine during a finite time in the Universe. High school or undergraduate teachers can explore this subject in an instigating, interdisciplinary, and historical way.
DOI: 10.6084/m9.figshare.14325869.v1
title: The black hole and its shadow

description: Abstract The most commented scientific image in 2019 was the image of M87*, the central supermassive black hole at the Messier 87 galaxy. From the Event Horizon Telescope's observation, we were able to see a black hole. Indeed, the famous image shows us the shadow of M87*. In this article, the concept of black hole shadow will be introduced as well as its importance to researches in gravitation and cosmology.
DOI: 10.6084/m9.figshare.14325869
title: The black hole and its shadow

description: Abstract The most commented scientific image in 2019 was the image of M87*, the central supermassive black hole at the Messier 87 galaxy. From the Event Horizon Telescope's observation, we were able to see a black hole. Indeed, the famous image shows us the shadow of M87*. In this article, the concept of black hole shadow will be introduced as well as its importance to researches in gravitation and cosmology.
DOI: 10.6084/m9.figshare.14206721
title: Measurable residual disease in pediatric acute myeloid leukemia: a systematic review

description: <b>Introduction</b>: A systematic review was performed to assess the prognostic value of Measurable Residual Disease (MRD) during treatment, for relapse and overall survival in pediatric acute myeloid leukemia (AML). <b>Areas covered</b>: A systematic search of available literature was performed to identify original full-text articles concerning MRD as prognostic for relapse and survival in pediatric AML. Thirteen studies were included, and in all studies, MRD positivity during treatment was associated with worse clinical outcome. MRD positivity was significantly associated with a higher probability of relapse in eleven studies. However, MRD negativity does not exclude the possibility of relapse in pediatric AML, while positivity early during therapy does not exclude cure. <b>Expert opinion</b>: MRD positivity during treatment has emerged as the most powerful prognostic factor in pediatric AML concerning relapse and overall survival and is useful for risk-group adapted treatment. Future studies should identify the optimal time-point(s) for MRD measurements and the optimal technique, to further improve its prognostic significance.
DOI: 10.6084/m9.figshare.14206721.v1
title: Measurable residual disease in pediatric acute myeloid leukemia: a systematic review

description: <b>Introduction</b>: A systematic review was performed to assess the prognostic value of Measurable Residual Disease (MRD) during treatment, for relapse and overall survival in pediatric acute myeloid leukemia (AML). <b>Areas covered</b>: A systematic search of available literature was performed to identify original full-text articles concerning MRD as prognostic for relapse and survival in pediatric AML. Thirteen studies were included, and in all studies, MRD positivity during treatment was associated with worse clinical outcome. MRD positivity was significantly associated with a higher probability of relapse in eleven studies. However, MRD negativity does not exclude the possibility of relapse in pediatric AML, while positivity early during therapy does not exclude cure. <b>Expert opinion</b>: MRD positivity during treatment has emerged as the most powerful prognostic factor in pediatric AML concerning relapse and overall survival and is useful for risk-group adapted treatment. Future studies should identify the optimal time-point(s) for MRD measurements and the optimal technique, to further improve its prognostic significance.
DOI: 10.6084/m9.figshare.14325870
title: A physical sense for fractional modeling: The Case of damping electromagnetic waves

description: Electromagnetic waves are present in our daily lives, being useful in several areas. These can be seen permeating the theories of medicine, geophysics, geology, physics, among others. In geophysics, for example, they appear very frequently in electromagnetic methods, where magnetic fields, electric potentials and electromagnetic waves are used. Electromagnetic waves arise from Maxwell’s equations, which are linear equations in a vacuum or inside atoms and nuclei and, considering these cases, give rise to differential linear equations. However, the deduced equations are always solved using classical methods of solving whole order differential equations. Therefore, the objective of this work is to analyze the propagation of an electromagnetic wave in a vacuum, for an integer and fractional order equation, solving them through the modified method of Laplace decomposition (MMDL). The new proposed solution allows a variation of the fractional parameter value, rescuing the solutions of the equations of the electromagnetic waves that propagate in material media, making it possible to analyze the different types of damping for the most varied media.
DOI: 10.6084/m9.figshare.14325870.v1
title: A physical sense for fractional modeling: The Case of damping electromagnetic waves

description: Electromagnetic waves are present in our daily lives, being useful in several areas. These can be seen permeating the theories of medicine, geophysics, geology, physics, among others. In geophysics, for example, they appear very frequently in electromagnetic methods, where magnetic fields, electric potentials and electromagnetic waves are used. Electromagnetic waves arise from Maxwell’s equations, which are linear equations in a vacuum or inside atoms and nuclei and, considering these cases, give rise to differential linear equations. However, the deduced equations are always solved using classical methods of solving whole order differential equations. Therefore, the objective of this work is to analyze the propagation of an electromagnetic wave in a vacuum, for an integer and fractional order equation, solving them through the modified method of Laplace decomposition (MMDL). The new proposed solution allows a variation of the fractional parameter value, rescuing the solutions of the equations of the electromagnetic waves that propagate in material media, making it possible to analyze the different types of damping for the most varied media.
DOI: 10.6084/m9.figshare.14325872
title: Attenuation of light by material media: a modeling activity involving three didactic experiments

description: The attenuation of light by material medium is little discussed in Physics degree courses, especially in experimental classes. In this article, a laboratory activity on this theme is discussed to be conducted with the teaching methodology of Modeling Episodes. The activity comprises three experiments, explored from the perspective of Didactic-Scientific Modeling in order to make sense specially of the concept of expanding a theoretical model. The problematization of the investigations is derived from discussions about how water pollution influences the photic zone of the oceans. In order to answer the questions raised, it is necessary to expand the model of propagation of light in a vacuum, including processes of absorption and scattering of light by matter, which was done through Beer-Lambert’s law. With the proposed practices, it is sought to highlight how a theoretical model of Physics can be improved through the inclusion of previously disregarded effects, thus expanding its domain of validity and predictive capacity, enabling the conduct of discussions on the nature of the scientific modeling process in experimental classes. In order to empirically contrast the expanded theoretical model, three experiments were done, each one of them in defferent media (glass, solution of water + table salt and smoke), using lasers and lamps as light emitting source. Particular emphasis was given to the role of the idealizations assumed in the process of construction, use and validation of the constructed model, seeking to evaluate, in each situation, the consequences of these simplifications of reality. From the results of the experiments, it is concluded that: i. the expanded theoretical model describes the attenuation of light intensity in material media with good precision, and ii. the pollution of the oceans can contribute to increase the extinction of sunlight, thus decreasing its penetration in the photic zone, reducing the photosynthesis rate of the algae. This article can contribute to the field of Physics teaching, not only bringing an innovative laboratory teaching activity, but also serving as a reference for those teachers interested in the practical application of modeling activities, in particular those focused on the expansion of a theoretical model.
DOI: 10.6084/m9.figshare.14325872.v1
title: Attenuation of light by material media: a modeling activity involving three didactic experiments

description: The attenuation of light by material medium is little discussed in Physics degree courses, especially in experimental classes. In this article, a laboratory activity on this theme is discussed to be conducted with the teaching methodology of Modeling Episodes. The activity comprises three experiments, explored from the perspective of Didactic-Scientific Modeling in order to make sense specially of the concept of expanding a theoretical model. The problematization of the investigations is derived from discussions about how water pollution influences the photic zone of the oceans. In order to answer the questions raised, it is necessary to expand the model of propagation of light in a vacuum, including processes of absorption and scattering of light by matter, which was done through Beer-Lambert’s law. With the proposed practices, it is sought to highlight how a theoretical model of Physics can be improved through the inclusion of previously disregarded effects, thus expanding its domain of validity and predictive capacity, enabling the conduct of discussions on the nature of the scientific modeling process in experimental classes. In order to empirically contrast the expanded theoretical model, three experiments were done, each one of them in defferent media (glass, solution of water + table salt and smoke), using lasers and lamps as light emitting source. Particular emphasis was given to the role of the idealizations assumed in the process of construction, use and validation of the constructed model, seeking to evaluate, in each situation, the consequences of these simplifications of reality. From the results of the experiments, it is concluded that: i. the expanded theoretical model describes the attenuation of light intensity in material media with good precision, and ii. the pollution of the oceans can contribute to increase the extinction of sunlight, thus decreasing its penetration in the photic zone, reducing the photosynthesis rate of the algae. This article can contribute to the field of Physics teaching, not only bringing an innovative laboratory teaching activity, but also serving as a reference for those teachers interested in the practical application of modeling activities, in particular those focused on the expansion of a theoretical model.
DOI: 10.6084/m9.figshare.14325875
title: Gravity acceleration: Analysis of didactic experiments

description: Abstract It is possible to determine experimentally the value of the acceleration of gravity by different experiments, from the simplest to the most complex. The aim of the article is to provide assistance for the professor's decision making regarding their teaching approach. These experiments present significant variations with respect to the accuracy of the experimental value found, apparatus and technologies used, experiment precision among other aspects. We present four experiments that will be compared with each other regarding: accuracy, sources of uncertainty and technologies used to carry out the experiment. The best performing experiment used a simple pendulum.
DOI: 10.6084/m9.figshare.14325875.v1
title: Gravity acceleration: Analysis of didactic experiments

description: Abstract It is possible to determine experimentally the value of the acceleration of gravity by different experiments, from the simplest to the most complex. The aim of the article is to provide assistance for the professor's decision making regarding their teaching approach. These experiments present significant variations with respect to the accuracy of the experimental value found, apparatus and technologies used, experiment precision among other aspects. We present four experiments that will be compared with each other regarding: accuracy, sources of uncertainty and technologies used to carry out the experiment. The best performing experiment used a simple pendulum.
DOI: 10.6084/m9.figshare.14325878.v1
title: Development of a theoretical approach of the thermals waves concept for understanding of the temperature variation in thin films and solid

description: Abstract The current work establishes an analysis of the electromagnetic waves concepts and its application in the process of heat diffusion in solids in order to understand and spread the concept of thermal waves, so little addressed within the academy. It is possible to identify with this analysis how the temperature can change as a function of the thermophysical properties of the materials when a sample is subjected to a modulated and periodic excitation by means of electromagnetic waves. This allows some photothermal techniques, for instance, photothermal radiometry, to determine the thermal properties of materials such as thin films and homogeneous solids. The content developed in this article can be widely addressed in the form of disciplines in undergraduate and graduate courses intended for physics, engineering and students of related fields.
DOI: 10.6084/m9.figshare.14325878
title: Development of a theoretical approach of the thermals waves concept for understanding of the temperature variation in thin films and solid

description: Abstract The current work establishes an analysis of the electromagnetic waves concepts and its application in the process of heat diffusion in solids in order to understand and spread the concept of thermal waves, so little addressed within the academy. It is possible to identify with this analysis how the temperature can change as a function of the thermophysical properties of the materials when a sample is subjected to a modulated and periodic excitation by means of electromagnetic waves. This allows some photothermal techniques, for instance, photothermal radiometry, to determine the thermal properties of materials such as thin films and homogeneous solids. The content developed in this article can be widely addressed in the form of disciplines in undergraduate and graduate courses intended for physics, engineering and students of related fields.
DOI: 10.6084/m9.figshare.14325879.v1
title: Dynamics of a physical pendulum with a magnet in the presence of a coil

description: Abstract We investigated the dynamics of a wood physical pendulum, supported by a PVC structure and having a magnet glued to its oscillating end and whose oscillation occurred in the vicinity of a coil that was sometimes in short-circuit, sometimes in open-circuit. The pendulum trajectory, position as a function of time, was drawn with the aid of frame-by-frame video analysis, helping to detect a greater damping of the oscillation in the presence of the coil in short-circuit. The equations of motion for the pendulum were modeled and solved, showing to be satisfactory to describe the observed dynamics and, thus, used to make an interesting prediction of interaction between the permanent and induced magnetic fields in the case of an analogous system to be built with distinctive construction characteristics (reduced moment of inertia and increased magnet field). We hope that the work can serve as a stimulus to quantitative investigations of simple systems and will motivate the significant learning of Mechanics and Electromagnetism.
DOI: 10.6084/m9.figshare.14325879
title: Dynamics of a physical pendulum with a magnet in the presence of a coil

description: Abstract We investigated the dynamics of a wood physical pendulum, supported by a PVC structure and having a magnet glued to its oscillating end and whose oscillation occurred in the vicinity of a coil that was sometimes in short-circuit, sometimes in open-circuit. The pendulum trajectory, position as a function of time, was drawn with the aid of frame-by-frame video analysis, helping to detect a greater damping of the oscillation in the presence of the coil in short-circuit. The equations of motion for the pendulum were modeled and solved, showing to be satisfactory to describe the observed dynamics and, thus, used to make an interesting prediction of interaction between the permanent and induced magnetic fields in the case of an analogous system to be built with distinctive construction characteristics (reduced moment of inertia and increased magnet field). We hope that the work can serve as a stimulus to quantitative investigations of simple systems and will motivate the significant learning of Mechanics and Electromagnetism.
DOI: 10.6084/m9.figshare.14325881
title: Particle motion analysis in a vertical circular loop using limit concepts

description: Abstract In this work, we will analyze the condition to a particle leave the contact with a vertical circular loop. This is a typical problem shows in textbooks of Physics, here we will present three different forms to solve it. For that, we will use only fundamental math concepts, it means without use differential calculus. We will show you that, although this analysis is been constructed in intuitive principles, it is equivalent to what is traditional show in textbooks. Overall we will discuss a special case, where a similar deduction of ours leave a false conclusion.
DOI: 10.6084/m9.figshare.14325882.v1
title: Lorentz transformations in the light front

description: Abstract In undergraduate and graduate courses, one usually studies the Lorentz's transformation defined in four-dimensional space: three spatial dimensions and one temporal. In this work we present an alternative way for the Lorentz's transformations using the light front coordinates via Minkowski space-time and its properties. Dirac in one of his works, published in 1949, introduced three different forms of relativistic dynamics: the usual or most common one, called instant form, characterized by the hypersurface specified by the boundary conditions defined at t = 0 and time evolution for the system at instances t &gt; 0; the point form, whose surface is a hyperboloid, and are described by the initial conditions x μ x μ = a 2 with the constant a and t &gt; 0 and the light front form, whose hypersurface is tangent to the light cone, being defined by the initial conditions at x + = c 2 ( t + z c ) = 0 and the “time evolution” for “instances x + &gt; 0”. Therefore, the variable x + plays the role of light-front “time”. The results we present here are connected to the study of Lorentz's transformations using light-cone coordinates and its consequences in the outcome expressions for diverse physical quantities of interest.
DOI: 10.6084/m9.figshare.14325882
title: Lorentz transformations in the light front

description: Abstract In undergraduate and graduate courses, one usually studies the Lorentz's transformation defined in four-dimensional space: three spatial dimensions and one temporal. In this work we present an alternative way for the Lorentz's transformations using the light front coordinates via Minkowski space-time and its properties. Dirac in one of his works, published in 1949, introduced three different forms of relativistic dynamics: the usual or most common one, called instant form, characterized by the hypersurface specified by the boundary conditions defined at t = 0 and time evolution for the system at instances t &gt; 0; the point form, whose surface is a hyperboloid, and are described by the initial conditions x μ x μ = a 2 with the constant a and t &gt; 0 and the light front form, whose hypersurface is tangent to the light cone, being defined by the initial conditions at x + = c 2 ( t + z c ) = 0 and the “time evolution” for “instances x + &gt; 0”. Therefore, the variable x + plays the role of light-front “time”. The results we present here are connected to the study of Lorentz's transformations using light-cone coordinates and its consequences in the outcome expressions for diverse physical quantities of interest.
DOI: 10.6084/m9.figshare.14325884
title: Test-particles motion in Reissner-Nordström spacetime

description: Abstract Test-particles motion can be analyzed using the tools of the Theory of General Relativity. Some classical verifications of this theory involve test-particles trajectories in the spherically symmetric spacetime associated to the Schwarzschild solution. Another spacetime with this symmetry is the one described by the Reissner-Nordström solution, associated to a spherical distribution of mass and electric charge as, for instance, a charged black hole. In this spacetime, we analyze the motion of free particles, which follow geodesics, and of particles with electric charge, which, therefore, interact electrically with the central object.
DOI: 10.6084/m9.figshare.14325884.v1
title: Test-particles motion in Reissner-Nordström spacetime

description: Abstract Test-particles motion can be analyzed using the tools of the Theory of General Relativity. Some classical verifications of this theory involve test-particles trajectories in the spherically symmetric spacetime associated to the Schwarzschild solution. Another spacetime with this symmetry is the one described by the Reissner-Nordström solution, associated to a spherical distribution of mass and electric charge as, for instance, a charged black hole. In this spacetime, we analyze the motion of free particles, which follow geodesics, and of particles with electric charge, which, therefore, interact electrically with the central object.
DOI: 10.6084/m9.figshare.14325890
title: An introduction to strange stars

description: Abstract The description of the densest neutron stars found in Nature depends on the understanding of the physical concepts present in General Relativity and in the theory of strong interactions – the Quantum Chromodynamics. In this work we review the essential concepts to describe strange stars, constituted by quarks up, down and strange, which is one of the alternatives for the composition of ultradense neutron stars. We will review the Bodmer-Witten-Terazawa hypothesis, which states that the strange matter is absolutely stable in relation to the ordinary nuclear matter, and discuss the basic properties that characterize strange stars. Our goal is to present the necessary concepts to understand this important theme of Astroparticles.