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Physics, Volume 2, Issue 3 (September 2020) – 11 articles

Cover Story (view full-size image): In the current respiratory COVID-19 pandemic, airborne virus-laden aerosols are considered as the primary route of transmission of SARS-CoV-2 pathogen. Staying in the air for a long enough time (minutes or hours), aerosol particles can be transferred over a long distance in an indoor environment to be inhaled by a susceptible host. Face cover masks are currently treated as the best accepted personal protective equipment (PPE) in mitigating aerosol dispersal. The material barrier of masks makes it uncomfortable to wear them in certain situations. The individually portable air curtain is a non-material barrier based, highly effective, PPE dynamically displacing the trajectories of infected particles that would otherwise be inhaled by an uninfected individual from reaching the surface and the openings of the host’s protected face. View this paper
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Review
The Higgs Field and Early Universe Cosmology: A (Brief) Review
Physics 2020, 2(3), 503-520; https://doi.org/10.3390/physics2030028 - 21 Sep 2020
Cited by 1 | Viewed by 776
Abstract
We review and discuss recent work exploring the implications of the Higgs field for early universe cosmology, and vice versa. Depending on the model under consideration, the Higgs may be one of a few scalar fields determining the evolution and fate of the [...] Read more.
We review and discuss recent work exploring the implications of the Higgs field for early universe cosmology, and vice versa. Depending on the model under consideration, the Higgs may be one of a few scalar fields determining the evolution and fate of the Universe, or the Higgs field may be connected to a rich sector of scalar moduli with complicated dynamics. In particular, we look at the potential consequences of the Higgs field for inflation and its predictions, for the (meta)stability of the Standard Model vacuum, and for the existence of dynamical selection mechanisms in the landscape. Full article
(This article belongs to the Special Issue The Higgs Boson: Present Status and Future Prospects)
Review
Low-Dimensional Nanostructures for Electrochemical Energy Applications
Physics 2020, 2(3), 481-502; https://doi.org/10.3390/physics2030027 - 11 Sep 2020
Viewed by 761
Abstract
Materials with different nanostructures can have diverse physical properties, and they exhibit unusual properties as compared to their bulk counterparts. Therefore, the structural control of desired nanomaterials is intensely attractive to many scientific applications. In this brief review, we mainly focus on reviewing [...] Read more.
Materials with different nanostructures can have diverse physical properties, and they exhibit unusual properties as compared to their bulk counterparts. Therefore, the structural control of desired nanomaterials is intensely attractive to many scientific applications. In this brief review, we mainly focus on reviewing our recent reports based on the materials of graphene and the transition metal chalcogenide, which have various low-dimensional nanostructures, in relation to the use of electrocatalysts in electrochemical energy applications; moreover, related literatures were also partially selected for discussion. In addition, future aspects of the nanostructure design related to the further enhancement of the performance of pertinent electrochemical energy devices will also be mentioned. Full article
(This article belongs to the Special Issue Advanced Energy Materials)
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Review
Fractal Structures of Yang–Mills Fields and Non-Extensive Statistics: Applications to High Energy Physics
Physics 2020, 2(3), 455-480; https://doi.org/10.3390/physics2030026 - 10 Sep 2020
Cited by 4 | Viewed by 1218
Abstract
In this work, we provide an overview of the recent investigations on the non-extensive Tsallis statistics and its applications to high energy physics and astrophysics, including physics at the Large Hadron Collider (LHC), hadron physics, and neutron stars. We review some recent investigations [...] Read more.
In this work, we provide an overview of the recent investigations on the non-extensive Tsallis statistics and its applications to high energy physics and astrophysics, including physics at the Large Hadron Collider (LHC), hadron physics, and neutron stars. We review some recent investigations on the power-law distributions arising in high energy physics experiments focusing on a thermodynamic description of the system formed, which could explain the power-law behavior. The possible connections with a fractal structure of hadrons is also discussed. The main objective of the present work is to delineate the state-of-the-art of those studies and show some open issues that deserve more careful investigation. We propose several possibilities to test the theory through analyses of experimental data. Full article
(This article belongs to the Special Issue Statistical Approaches in High Energy Physics)
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Article
Searching for Supersymmetry at LHC Using the Complex-Network-Based Method of the Three-Dimensional Visibility-Graph
Physics 2020, 2(3), 436-454; https://doi.org/10.3390/physics2030025 - 10 Sep 2020
Viewed by 800
Abstract
For the last several decades, there has been tremendous interest in search for Supersymmetry (SUSY) in the area of high energy physics. At Large Hadron Collider (LHC), there have been continuous searches for SUSY for prompt and non-prompt, for particle R-parity conserving [...] Read more.
For the last several decades, there has been tremendous interest in search for Supersymmetry (SUSY) in the area of high energy physics. At Large Hadron Collider (LHC), there have been continuous searches for SUSY for prompt and non-prompt, for particle R-parity conserving and R-parity violating generation and decays. The limits obtained from these experiments and analyses for detection of the signatures of supersymmetric particles (LSP), revealed greater possibilities of such experiments in the collider. However, these signatures are usually derived under the assumption of bit optimistic conditions of the decaying process of sparticles to the final states. Moreover, SUSY might have been in a disguised state at lower mass-scales as a result of difficult and challenging mass spectra and mixed modes of decays. In this investigation, a novel method of 3-dimensional (3D) Visibility-Graph Analysis is proposed. This is an extension of Visibility Graph analysis of data series to perform the scaling analysis for 3D space. The experimental data spaces analyzed are made up of the component-space (in the X,Y and Z coordinates) of transverse momentum (pT) values taken out from 4-momenta of the signatures of the final state of the pair of mega-jets extracted from the multiJet primary pp collision data from Run B of 2010 at 7 TeV which was used for the search of SUSY using razor filter. The symmetry scaling and the inherent scaling behavior, scale-freeness of multi-particle production process is studied in terms of 3D Power-of-Scale-freeness-of-Visibility-Graph (3D-PSVG) extracted from the 3D Visibility Graphs constructed out of the experimental data spaces. The signature of SUSY may be identified by analyzing the scaling behavior and long-range correlation inherent in the 3D space made up of signatures of final state of multi-particles produced in the pp collision at 7 TeV, for the analysis of SUSY, which the conventional method of analyzing the spectrum of invariant mass or pT may miss. Full article
(This article belongs to the Special Issue Statistical Approaches in High Energy Physics)
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Article
Gauge Functions in Classical Mechanics: From Undriven to Driven Dynamical Systems
Physics 2020, 2(3), 425-435; https://doi.org/10.3390/physics2030024 - 09 Sep 2020
Viewed by 690
Abstract
Novel gauge functions are introduced to non-relativistic classical mechanics and used to define forces. The obtained results show that the gauge functions directly affect the energy function and allow for converting an undriven physical system into a driven one. This is a novel [...] Read more.
Novel gauge functions are introduced to non-relativistic classical mechanics and used to define forces. The obtained results show that the gauge functions directly affect the energy function and allow for converting an undriven physical system into a driven one. This is a novel phenomenon in dynamics that resembles the role of gauges in quantum field theories. Full article
(This article belongs to the Section Classical Physics)
Review
Highly Active Carbon-Based Electrocatalysts for Dye-Sensitized Solar Cells: A Brief Review
Physics 2020, 2(3), 412-424; https://doi.org/10.3390/physics2030023 - 08 Sep 2020
Cited by 1 | Viewed by 685
Abstract
Dye-sensitized solar cells (DSSCs) have emerged as promising alternatives to traditional silicon-based solar cells due to their relatively high conversion efficiency, low cost, flexibility, and environmentally benign fabrication processes. In DSSCs, platinum (Pt)-based materials used as the counter electrode (CE) exhibit the superior [...] Read more.
Dye-sensitized solar cells (DSSCs) have emerged as promising alternatives to traditional silicon-based solar cells due to their relatively high conversion efficiency, low cost, flexibility, and environmentally benign fabrication processes. In DSSCs, platinum (Pt)-based materials used as the counter electrode (CE) exhibit the superior catalytic ability toward the reduction reaction of triiodide ions, which are attributed to their excellent catalytic activity and high electrical conductivity. However, Pt-based materials with high cost and limited supply hinder them from mass production. Developing highly active and stable CE materials without noble metals has been a persistent challenge for the practical application in DSSCs. Recently, a number of earth-abundant catalysts, especially carbon-based materials, display high activity, low cost, and good stability that render them attractive candidates to replace Pt in DSSCs. Herein, we will briefly review recent progress on carbon-based electrocatalysts as CEs in DSSC applications. The strategies of improving the catalytic activity of carbon-based materials such as structural engineering and/or heteroatom doping will be introduced. The active sites toward the reduction reaction of triiodide ions summarized from experimental results or theoretical calculation will also be discussed. Finally, the futuristic prospects and challenges of carbon-based electrocatalysts as CEs in DSSCs will be briefly mentioned. Full article
(This article belongs to the Special Issue Advanced Energy Materials)
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Article
Antimatter Gravity: Second Quantization and Lagrangian Formalism
Physics 2020, 2(3), 397-411; https://doi.org/10.3390/physics2030022 - 03 Sep 2020
Viewed by 922
Abstract
The application of the CPT (charge-conjugation, parity, and time reversal) theorem to an apple falling on Earth leads to the description of an anti-apple falling on anti–Earth (not on Earth). On the microscopic level, the Dirac equation in curved space-time simultaneously describes spin-1/2 particles and their antiparticles coupled to the same curved space-time metric (e.g., the metric describing the gravitational field of the Earth). On the macroscopic level, the electromagnetically and gravitationally coupled Dirac equation therefore describes apples and anti-apples, falling on Earth, simultaneously. A particle-to-antiparticle transformation of the gravitationally coupled Dirac equation therefore yields information on the behavior of “anti-apples on Earth”. However, the problem is exacerbated by the fact that the operation of charge conjugation is much more complicated in curved, as opposed to flat, space-time. Our treatment is based on second-quantized field operators and uses the Lagrangian formalism. As an additional helpful result, prerequisite to our calculations, we establish the general form of the Dirac adjoint in curved space-time. On the basis of a theorem, we refute the existence of tiny, but potentially important, particle-antiparticle symmetry breaking terms in which possible existence has been investigated in the literature. Consequences for antimatter gravity experiments are discussed. Full article
(This article belongs to the Special Issue Beyond the Standard Models of Physics and Cosmology)
Article
Two-Qubit Bloch Sphere
Physics 2020, 2(3), 383-396; https://doi.org/10.3390/physics2030021 - 02 Aug 2020
Viewed by 1634
Abstract
Three unit spheres were used to represent the two-qubit pure states. The three spheres are named the base sphere, entanglement sphere, and fiber sphere. The base sphere and entanglement sphere represent the reduced density matrix of the base qubit and the non-local entanglement [...] Read more.
Three unit spheres were used to represent the two-qubit pure states. The three spheres are named the base sphere, entanglement sphere, and fiber sphere. The base sphere and entanglement sphere represent the reduced density matrix of the base qubit and the non-local entanglement measure, concurrence, while the fiber sphere represents the fiber qubit via a simple rotation under a local single-qubit unitary operation; however, in an entangled bipartite state, the fiber sphere has no information on the reduced density matrix of the fiber qubit. When the bipartite state becomes separable, the base and fiber spheres seamlessly become the single-qubit Bloch spheres of each qubit. Since either qubit can be chosen as the base qubit, two alternative sets of these three spheres are available, where each set fully represents the bipartite pure state, and each set has information of the reduced density matrix of its base qubit. Comparing this model to the two Bloch balls representing the reduced density matrices of the two qubits, each Bloch ball corresponds to two unit spheres in our model, namely, the base and entanglement spheres. The concurrence–coherence complementarity is explicitly shown on the entanglement sphere via a single angle. Full article
(This article belongs to the Section Atomic Physics)
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Article
An Analysis of the Italian Lockdown in Retrospective Using Particle Swarm Optimization in Machine Learning Applied to an Epidemiological Model
Physics 2020, 2(3), 368-382; https://doi.org/10.3390/physics2030020 - 01 Aug 2020
Cited by 2 | Viewed by 1584
Abstract
A critical analysis of the open data provided by the Italian Civil Protection Centre during phase 1 of Covid-19 epidemic—the so-called Italian lockdown—is herein proposed in relation to four of the most affected Italian regions, namely Lombardy, Reggio Emilia, Valle d’Aosta, and Veneto. [...] Read more.
A critical analysis of the open data provided by the Italian Civil Protection Centre during phase 1 of Covid-19 epidemic—the so-called Italian lockdown—is herein proposed in relation to four of the most affected Italian regions, namely Lombardy, Reggio Emilia, Valle d’Aosta, and Veneto. A possible bias in the data induced by the extent in the use of medical swabs is found in relation to Valle d’Aosta and Veneto. Observed data are then interpreted using a Susceptible-Infectious-Recovered (SIR) epidemiological model enhanced with asymptomatic (infected and recovered) compartments, including lockdown effects through time-dependent model parameters. The initial number of susceptible individuals for each region is also considered as a parameter to be identified. The issue of parameters identification is herein addressed by a robust machine learning approach based on particle swarm optimization. Model predictions provide relevant information for policymakers in terms of the effect of lockdown measures in the different regions. The number of susceptible individuals involved in the epidemic, important for a safe release of lockdown during the next phases, is predicted to be around 10% of the population for Lombardy, 16% for Reggio Emilia, 18% for Veneto, and 40% for Valle d’Aosta. Full article
(This article belongs to the Special Issue Physics Methods in Coronavirus Pandemic Analysis)
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Article
Self-Inductance of the Circular Coils of the Rectangular Cross-Section with the Radial and Azimuthal Current Densities
Physics 2020, 2(3), 352-367; https://doi.org/10.3390/physics2030019 - 13 Jul 2020
Cited by 2 | Viewed by 1120
Abstract
In this paper, we give new formulas for calculating the self-inductance for circular coils of the rectangular cross-sections with the radial and the azimuthal current densities. These formulas are given by the single integration of the elementary functions which are integrable on the [...] Read more.
In this paper, we give new formulas for calculating the self-inductance for circular coils of the rectangular cross-sections with the radial and the azimuthal current densities. These formulas are given by the single integration of the elementary functions which are integrable on the interval of the integration. From these new expressions, we can obtain the special cases for the self-inductance of the thin-disk pancake and the thin-wall solenoids that confirm the validity of this approach. For the asymptotic cases, the new formula for the self-inductance of the thin-wall solenoid is obtained for the first time in the literature. In this paper, we do not use special functions such as the elliptical integrals of the first, second and third kind, nor Struve and Bessel functions because that is very tedious work. The results of this work are compared with already different known methods and all results are in excellent agreement. We consider this approach novel because of its simplicity in the self-inductance calculation of the previously-mentioned configurations. Full article
(This article belongs to the Section Applied Physics)
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Article
Study of an Air Curtain in the Context of Individual Protection from Exposure to Coronavirus (SARS-CoV-2) Contained in Cough-Generated Fluid Particles
Physics 2020, 2(3), 340-351; https://doi.org/10.3390/physics2030018 - 06 Jul 2020
Cited by 1 | Viewed by 2970
Abstract
The ongoing respiratory COVID-19 pandemic has heavily impacted the social and private lives of the majority of the global population. This infection is primarily transmitted via virus-laden fluid particles (i.e., droplets and aerosols) that are formed in the respiratory tract of infected individuals [...] Read more.
The ongoing respiratory COVID-19 pandemic has heavily impacted the social and private lives of the majority of the global population. This infection is primarily transmitted via virus-laden fluid particles (i.e., droplets and aerosols) that are formed in the respiratory tract of infected individuals and expelled from the mouth in the course of breathing, talking, coughing, and sneezing. To mitigate the risk of virus transmission, in many places of the world, the public has been asked or even obliged to use face covers. It is plausible that in the years ahead we will see the use of face masks, face shields and respirators become a normal practice in our life. However, wearing face covers is uncomfortable in some situations, like, for example, in summer heat, while staying on beaches or at hotel swimming pools, doing exercises in gyms, etc. Also, most types of face cover become contaminated with time and need to be periodically replaced or disinfected. These nuisances are caused by the fact that face covers are based on material barriers, which prevent inward and outward propagation of aerosol and droplets containing the pathogen. Here, we study a non-material based protection barrier created by a flow of well directed down stream of air across the front of the open face. The protection is driven by dragging virus-laden particles inside the width of the air flow and hence, as a consequence, displacing them away from their primary trajectories. Applying well established gas-particle flow formalism, we analyzed the dynamics of aerosols and droplets at different regimes of the flow laying over the bodies of the fluid particles. The analysis allowed us to establish the rates of velocity gain of the fluid particles of dimensions relevant for the pathogen transmissions, while they are crossing the width of the air barrier. On the basis of this analysis, we provide a comprehensive study of the protection effectiveness of the air barrier for a susceptible individual located indoor, in an infected environment. Our study shows that such, potentially portable, air curtains can effectively provide both inward and outward protection and serve as an effective personal protective equipment (PPE) mitigating human to human transmission of virus infection like COVID-19. Full article
(This article belongs to the Section Applied Physics)
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