T he emergent field of stochastic thermodynamics uses random variables to investigate the dynamics of microscopic systems that operate out of thermodynamic equilibrium, such as active matter andmetabolic pathways. Now Naruo Ohga and two colleagues at the University of Tokyo have applied tools from stochastic thermodynamics to uncover a universal law that could find broad applications in the description of activematter, cell metabolism, and other systems whose continuous supply of energy keeps them out of equilibrium [1] (Fig. 1.)
{"title":"Time-Reversal Symmetry and Thermodynamic Forces","authors":"Hyun-Myung Chun","doi":"10.1103/physics.16.142","DOIUrl":"https://doi.org/10.1103/physics.16.142","url":null,"abstract":"T he emergent field of stochastic thermodynamics uses random variables to investigate the dynamics of microscopic systems that operate out of thermodynamic equilibrium, such as active matter andmetabolic pathways. Now Naruo Ohga and two colleagues at the University of Tokyo have applied tools from stochastic thermodynamics to uncover a universal law that could find broad applications in the description of activematter, cell metabolism, and other systems whose continuous supply of energy keeps them out of equilibrium [1] (Fig. 1.)","PeriodicalId":20136,"journal":{"name":"Physics","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135022326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A bout 8% of the Solar System’s asteroids are made mostly of metal. Like rocky and icy asteroids, metal ones occasionally suffer destructive collisions that send fragments—meteorites—hurtling toward Earth. Some of those meteorites have magnetic fields, a property whose origin planetary scientists have struggled to understand. Now Zhongtian Zhang and David Bercovici of Yale University have proposed a plausible explanation for the field’s presence [1]. If their scenario finds observational support, it could provide insight into howmodestly sized objects in other solar systems acquire magnetic fields.
{"title":"How Metal Meteorites Magnetize","authors":"Charles Day","doi":"10.1103/physics.16.141","DOIUrl":"https://doi.org/10.1103/physics.16.141","url":null,"abstract":"A bout 8% of the Solar System’s asteroids are made mostly of metal. Like rocky and icy asteroids, metal ones occasionally suffer destructive collisions that send fragments—meteorites—hurtling toward Earth. Some of those meteorites have magnetic fields, a property whose origin planetary scientists have struggled to understand. Now Zhongtian Zhang and David Bercovici of Yale University have proposed a plausible explanation for the field’s presence [1]. If their scenario finds observational support, it could provide insight into howmodestly sized objects in other solar systems acquire magnetic fields.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135164096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N eutrinos are notoriously elusive. Interacting only via the weak force and gravity, they pass through regular baryonic matter almost unhindered. But like members of an exclusive social clique, neutrinos might be less standoffish among particles of their own type. Some beyond-standard-model theories predict a “secret” interaction that would cause neutrinos to scatter from one another when they gather at high enough densities. Po-Wen Chang at Ohio State University and his colleagues have now shown that, according to one neutrino-emission model, the effect of this neutrino self-interaction (νSI) could show up in future observations of supernovae [1].
{"title":"Supernovae Could Confess Neutrinos’ Secrets","authors":"Marric Stephens","doi":"10.1103/physics.16.s120","DOIUrl":"https://doi.org/10.1103/physics.16.s120","url":null,"abstract":"N eutrinos are notoriously elusive. Interacting only via the weak force and gravity, they pass through regular baryonic matter almost unhindered. But like members of an exclusive social clique, neutrinos might be less standoffish among particles of their own type. Some beyond-standard-model theories predict a “secret” interaction that would cause neutrinos to scatter from one another when they gather at high enough densities. Po-Wen Chang at Ohio State University and his colleagues have now shown that, according to one neutrino-emission model, the effect of this neutrino self-interaction (νSI) could show up in future observations of supernovae [1].","PeriodicalId":20136,"journal":{"name":"Physics","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135164095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A fusion reactor would generate electricity using the energy released by nuclear-fusion reactions occurring in a plasma. A key step in the race toward realizing the dream of such a reactor is the creation of a burning plasma—one in which the fusion reactions themselves supply most of the heating needed to keep the plasma at fusion-relevant temperatures. This step has recently been demonstrated for inertially confined plasmas [1, 2] (see Research News: Ignition First in a Fusion Reaction) but has so far remained elusive for magnetically confined ones. This goal
{"title":"Nuclear Fusion Heats Up","authors":"Maria Gatu Johnson","doi":"10.1103/physics.16.137","DOIUrl":"https://doi.org/10.1103/physics.16.137","url":null,"abstract":"A fusion reactor would generate electricity using the energy released by nuclear-fusion reactions occurring in a plasma. A key step in the race toward realizing the dream of such a reactor is the creation of a burning plasma—one in which the fusion reactions themselves supply most of the heating needed to keep the plasma at fusion-relevant temperatures. This step has recently been demonstrated for inertially confined plasmas [1, 2] (see Research News: Ignition First in a Fusion Reaction) but has so far remained elusive for magnetically confined ones. This goal","PeriodicalId":20136,"journal":{"name":"Physics","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135307891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W henmolecules or bacteria organize into a long-range pattern, researchers want to understand how themicroscopic interactions lead to the macroscopic order. Pietro Tierno of the University of Barcelona and his colleagues observed such self-organization in magnetic particles suspended in a liquid and subjected to an oscillating magnetic field [1]. Through experiments and simulations, the team showed that the resulting zigzag pattern is explained by the fluid flow generated around the oscillating particles, not by any details of the particles or the applied field. Similar zigzag patterns have also been seen in charged colloids subjected to
{"title":"Self-Organized Zigzags from Fluid Flow","authors":"David Ehrenstein","doi":"10.1103/physics.16.138","DOIUrl":"https://doi.org/10.1103/physics.16.138","url":null,"abstract":"W henmolecules or bacteria organize into a long-range pattern, researchers want to understand how themicroscopic interactions lead to the macroscopic order. Pietro Tierno of the University of Barcelona and his colleagues observed such self-organization in magnetic particles suspended in a liquid and subjected to an oscillating magnetic field [1]. Through experiments and simulations, the team showed that the resulting zigzag pattern is explained by the fluid flow generated around the oscillating particles, not by any details of the particles or the applied field. Similar zigzag patterns have also been seen in charged colloids subjected to","PeriodicalId":20136,"journal":{"name":"Physics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135491495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T ension was in the air on July 24 as members of the Muon g-2 Collaboration gathered in a conference room at the University of Liverpool, UK. The scientists had congregated to “unblind” their latest measurements of an anomalous property of the muon, an unstable particle that makes upmuch of the cosmic radiation that reaches Earth’s surface. When input into the computer, would the figures in two sealed envelopes reveal a match between the new analysis and a previous one? Or would the team have to announce that something had gone awry? There was a fear that values would be inconsistent with the collaboration’s earlier findings, says René Reimann, a physicist from the Johannes Gutenberg
{"title":"Mismatch with Standard-Model Predictions Reaches 5 Sigma","authors":"Katherine Wright","doi":"10.1103/physics.16.139","DOIUrl":"https://doi.org/10.1103/physics.16.139","url":null,"abstract":"T ension was in the air on July 24 as members of the Muon g-2 Collaboration gathered in a conference room at the University of Liverpool, UK. The scientists had congregated to “unblind” their latest measurements of an anomalous property of the muon, an unstable particle that makes upmuch of the cosmic radiation that reaches Earth’s surface. When input into the computer, would the figures in two sealed envelopes reveal a match between the new analysis and a previous one? Or would the team have to announce that something had gone awry? There was a fear that values would be inconsistent with the collaboration’s earlier findings, says René Reimann, a physicist from the Johannes Gutenberg","PeriodicalId":20136,"journal":{"name":"Physics","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135597508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new artificial intelligence algorithm can model the behavior of a set of objects, such as helical springs or pendulums, using a method that can extrapolate to objects that the algorithm hasn’t previously analyzed.
{"title":"AI Learns to Play with a Slinky","authors":"Michael Schirber","doi":"10.1103/physics.16.s119","DOIUrl":"https://doi.org/10.1103/physics.16.s119","url":null,"abstract":"A new artificial intelligence algorithm can model the behavior of a set of objects, such as helical springs or pendulums, using a method that can extrapolate to objects that the algorithm hasn’t previously analyzed.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"193 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135597676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T omake higher-density magnetic data systems, researchers are looking to crystalline materials that have switchable magnetic orientations. But for some of these materials, switching the magnetization direction—for example from spin-up to spin-down—requires overcoming a large energy barrier. Now Seiji Miyashita at the University of Tokyo and Bernard Barbara of the Institut Néel, CNRS Grenoble, France, predict that experimentalists could reverse a material’s magnetization by applying to it a specific sequence of microwave or optical-frequency pulses [1]. The approach could find applications in quantum information storage.
{"title":"Zap with Microwaves to Reverse Spin","authors":"Rachel Berkowitz","doi":"10.1103/physics.16.s118","DOIUrl":"https://doi.org/10.1103/physics.16.s118","url":null,"abstract":"T omake higher-density magnetic data systems, researchers are looking to crystalline materials that have switchable magnetic orientations. But for some of these materials, switching the magnetization direction—for example from spin-up to spin-down—requires overcoming a large energy barrier. Now Seiji Miyashita at the University of Tokyo and Bernard Barbara of the Institut Néel, CNRS Grenoble, France, predict that experimentalists could reverse a material’s magnetization by applying to it a specific sequence of microwave or optical-frequency pulses [1]. The approach could find applications in quantum information storage.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135745288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Solar chromosphere and photosphere, as well as solar atmospheric structures, such as prominences and spicules, are made of partially ionized plasmas. Observations have reported the presence of damped or amplified oscillations in these solar plasmas, which have been interpreted in terms of magnetohydrodynamic (MHD) waves. Slow magnetoacoustic waves could be responsible for these oscillations. The present study investigates the temporal behavior of the field-aligned motions that represent slow magnetoacoustic waves excited in a partially ionized prominence plasma by the ponderomotive force. Starting from single-fluid MHD equations, including radiative losses, a heating mechanism and ambipolar diffusion, and using a regular perturbation method, first- and second-order partial differential equations have been derived. By numerically solving second-order equations describing field-aligned motions, the temporal behavior of the longitudinal velocity perturbations is obtained. The damping or amplification of these perturbations can be explained in terms of heating–cooling misbalance, the damping effect due to ambipolar diffusion and the variation of the first adiabatic exponent with temperature and ionization degree.
{"title":"Nonlinear Coupling of Alfvén and Slow Magnetoacoustic Waves in Partially Ionized Solar Plasmas: The Effect of Thermal Misbalance","authors":"José Luis Ballester","doi":"10.3390/physics5020025","DOIUrl":"https://doi.org/10.3390/physics5020025","url":null,"abstract":"Solar chromosphere and photosphere, as well as solar atmospheric structures, such as prominences and spicules, are made of partially ionized plasmas. Observations have reported the presence of damped or amplified oscillations in these solar plasmas, which have been interpreted in terms of magnetohydrodynamic (MHD) waves. Slow magnetoacoustic waves could be responsible for these oscillations. The present study investigates the temporal behavior of the field-aligned motions that represent slow magnetoacoustic waves excited in a partially ionized prominence plasma by the ponderomotive force. Starting from single-fluid MHD equations, including radiative losses, a heating mechanism and ambipolar diffusion, and using a regular perturbation method, first- and second-order partial differential equations have been derived. By numerically solving second-order equations describing field-aligned motions, the temporal behavior of the longitudinal velocity perturbations is obtained. The damping or amplification of these perturbations can be explained in terms of heating–cooling misbalance, the damping effect due to ambipolar diffusion and the variation of the first adiabatic exponent with temperature and ionization degree.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136001648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Monitored differential infection rates of past corona waves are used to infer, a posteriori, the real time variation of the ratio of recovery to infection rate as a key parameter of the SIR (susceptible-infected-recovered/removed) epidemic model. From monitored corona waves in five different countries, it is found that this ratio exhibits a linear increase at early times below the first maximum of the differential infection rate, before the ratios approach a nearly constant value close to unity at the time of the first maximum with small amplitude oscillations at later times. The observed time dependencies at early times and at times near the first maximum agree favorably well with the behavior of the calculated ratio for the Gaussian temporal evolution of the rate of new infections, although the predicted linear increase of the Gaussian ratio at late times is not observed.
{"title":"Determination of a Key Pandemic Parameter of the SIR-Epidemic Model from Past COVID-19 Mutant Waves and Its Variation for the Validity of the Gaussian Evolution","authors":"Reinhard Schlickeiser, Martin Kröger","doi":"10.3390/physics5010016","DOIUrl":"https://doi.org/10.3390/physics5010016","url":null,"abstract":"Monitored differential infection rates of past corona waves are used to infer, a posteriori, the real time variation of the ratio of recovery to infection rate as a key parameter of the SIR (susceptible-infected-recovered/removed) epidemic model. From monitored corona waves in five different countries, it is found that this ratio exhibits a linear increase at early times below the first maximum of the differential infection rate, before the ratios approach a nearly constant value close to unity at the time of the first maximum with small amplitude oscillations at later times. The observed time dependencies at early times and at times near the first maximum agree favorably well with the behavior of the calculated ratio for the Gaussian temporal evolution of the rate of new infections, although the predicted linear increase of the Gaussian ratio at late times is not observed.","PeriodicalId":20136,"journal":{"name":"Physics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135728249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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