物理最新文献

{"title":"Inertial swimming in an Oldroyd-B fluid","authors":"N. Ali,&nbsp;M. Sajid","doi":"10.1140/epje/s10189-025-00485-4","DOIUrl":"10.1140/epje/s10189-025-00485-4","url":null,"abstract":"<p>The effects of fluid inertia on a self-propelling inextensible waving sheet in an Oldroyd-B fluid are examined. The swimming velocity of the sheet is calculated in the limit in which the amplitude of the waves propagating along the sheet is small relative to the wavelength of the waves. The rate of work done by the sheet is also calculated. It is found that the swimming speed decreases monotonically approaching a limiting value with increasing Reynolds number (<i>R</i>) for a Newtonian fluid. For an Oldroyd-B fluid, the swimming speed increases to a maximum and then decreases asymptotically to a limiting value with increasing <i>R</i>. In contrast, it increases monotonically to a limiting value with increasing <i>R</i> for a Maxwell fluid. The limiting value is highest for the Maxwell fluid and lowest for the Oldroyd-B fluid. The corresponding value for the Newtonian fluid lies in between. The rate of work done by the sheet increases with increasing Reynolds number for all Deborah numbers. However, the energy consumed at a fixed swimming speed is lesser for an Oldroyd-B fluid than that of a Newtonian fluid. These results suggest that contrary to the Newtonian case, the fluid inertia supports the swimming sheet motion in a complex fluid. At a particular Deborah number, the oscillation frequency of the sheet could be adjusted to achieve the maximum speed. Similarly, at a particular frequency of oscillation, the Deborah numbers could be adjusted to achieve the maximum speed. These observations are in sharp contrast with the previous results reported for Newtonian and second-order fluids.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"48 4-5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trackformers: in search of transformer-based particle tracking for the high-luminosity LHC era","authors":"Sascha Caron,&nbsp;Nadezhda Dobreva,&nbsp;Antonio Ferrer Sánchez,&nbsp;José D. Martín-Guerrero,&nbsp;Uraz Odyurt,&nbsp;Roberto Ruiz de Austri Bazan,&nbsp;Zef Wolffs,&nbsp;Yue Zhao","doi":"10.1140/epjc/s10052-025-14156-3","DOIUrl":"10.1140/epjc/s10052-025-14156-3","url":null,"abstract":"<div><p>High-Energy Physics experiments are facing a multi-fold data increase with every new iteration. This is certainly the case for the upcoming High-Luminosity LHC upgrade. Such increased data processing requirements forces revisions to almost every step of the data processing pipeline. One such step in need of an overhaul is the task of particle track reconstruction, a.k.a., <i>tracking</i>. A Machine Learning-assisted solution is expected to provide significant improvements, since the most time-consuming step in tracking is the assignment of hits to particles or track candidates. This is the topic of this paper. We take inspiration from large language models. As such, we consider two approaches: the prediction of the next word in a sentence (next hit point in a track), as well as the one-shot prediction of all hits within an event. In an extensive design effort, we have experimented with three models based on the Transformer architecture and one model based on the U-Net architecture, performing track association predictions for collision event hit points. In our evaluation, we consider a spectrum of simple to complex representations of the problem, eliminating designs with lower metrics early on. We report extensive results, covering both prediction accuracy (score) and computational performance. We have made use of the REDVID simulation framework, as well as reductions applied to the TrackML data set, to compose five data sets from simple to complex, for our experiments. The results highlight distinct advantages among different designs in terms of prediction accuracy and computational performance, demonstrating the efficiency of our methodology. Most importantly, the results show the viability of a one-shot encoder-classifier based Transformer solution as a practical approach for the task of tracking. \u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 4","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14156-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Maximum power point tracking based on improved sliding mode control","authors":"Abdelkader Ouacel,&nbsp;Benalia M’hamdi,&nbsp;Tahar Benaissa,&nbsp;Abderrahmane Amari,&nbsp;Matilde Pietrafesa,&nbsp;Mario Versaci","doi":"10.1140/epjp/s13360-025-06264-6","DOIUrl":"10.1140/epjp/s13360-025-06264-6","url":null,"abstract":"<div><p>Solar energy is a renewable, sustainable and definitely inexhaustible supply of power, in contrast to fossil fuels. Photovoltaic systems provide the cleanest, economic production of energy. However, photovoltaic structures are faced with the problem of maximum power point tracking (MPPT) and the need to provide the best of techniques that will operate efficiently in continuously varying atmospheric conditions. A novel MPPT algorithm based on sliding mode control for photovoltaic systems is proposed in this paper, to efficiently track maximum power under changing climate conditions. The effectiveness of the proposed MPPT algorithm, based on sliding mode control, is substantiated by a comparative study with three other methods, namely P&amp;O, GWO-based MPPT and PSO-based MPPT. On the basis of simulation results using MATLAB/Simulink software, the proposed method offers good tracking performance.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 4","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High critical current densities of body-centered cubic high-entropy alloy superconductors: recent research progress","authors":"Jiro Kitagawa,&nbsp;Yoshikazu Mizuguchi,&nbsp;Terukazu Nishizaki","doi":"10.1140/epjb/s10051-025-00922-5","DOIUrl":"10.1140/epjb/s10051-025-00922-5","url":null,"abstract":"<p>High-entropy alloy (HEA) superconductors have garnered significant attention due to their unique characteristics, such as robust superconductivity under extremely high pressure and irradiation, the cocktail effect, and the enhancement of the upper critical field. A high critical current density is another noteworthy feature observed in HEAs. Several body-centered cubic (bcc) HEAs have exhibited critical current densities comparable to those of Nb–Ti superconducting alloys. Such HEAs hold potential for applications as multifunctional superconducting wires, a capability rarely achieved in conventional alloys. In this context, we review recent advancements in research on critical current densities in bcc HEA superconductors, including <img>, <img>, NbScTiZr, and others. Comparative analyses among these HEAs reveal that both eutectic microstructures, which accompany lattice strain, and nano-sized precipitates play pivotal roles in achieving elevated critical current densities across wide magnetic field ranges. Furthermore, we propose several future directions for research. These include elucidating the origin of lattice strain, exploring more fine eutectic microstructures, artificially introducing nanoscale pinning sites, improving the superconducting critical temperature, and investigating the mechanical properties of these materials.</p>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 4","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photocontrol of bacterial membrane potential regulates antibiotic persistence in B. subtilis","authors":"Pietro Bertolotti,&nbsp;Federico Gallinardi,&nbsp;Marta Ghidoli,&nbsp;Chiara Bertarelli,&nbsp;Guglielmo Lanzani,&nbsp;Giuseppe Maria Paternò","doi":"10.1140/epjp/s13360-025-06263-7","DOIUrl":"10.1140/epjp/s13360-025-06263-7","url":null,"abstract":"<div><p>Bacterial persistence and resistance to antibiotics pose critical challenges in healthcare and environmental contexts. Recent studies revealing that bacteria possess a dynamic electrical membrane potential open new avenues for influencing bacterial behaviour and drug susceptibility. In this work, we present a novel light-responsive strategy to modulate bacterial antibiotic persistence using Ziapin2, an azobenzene photoswitch previously shown to alter bacterial membrane potential. We selected two broad-spectrum antibiotics with distinct modes of action: Kanamycin, which requires cytosolic uptake to inhibit protein synthesis, and Ampicillin, which targets cell wall polymerization at the cell envelope, to probe the role of membrane potential in antibiotic efficacy. Our findings show that when <i>Bacillus subtilis</i> is exposed to Kanamycin and Ziapin2, photoactivation (470 nm) significantly impacts bacterial viability: under illumination, the previously lethal effects of Kanamycin are markedly reduced, suggesting that membrane potential changes drive altered antibiotic uptake or intracellular accumulation. In contrast, Ampicillin-treated samples remain largely unaffected by light-induced membrane modulation, consistent with its action at the external cell envelope. Taken together, these results indicate that membrane potential manipulation can selectively influence the activity of antibiotics whose intracellular uptake is critical to their function. This proof-of-concept study underscores the potential of non-genetic, light-based interventions to modulate bacterial susceptibility in real time. Future work will expand this approach by exploring additional antibiotic classes and novel azobenzene derivatives, ultimately advancing our understanding of bacterial bioelectric regulation and its applications in antimicrobial therapies.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 4","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjp/s13360-025-06263-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transfer of diode pumped Er:YLF laser radiation by hollow glass waveguides","authors":"Zuzana Fialková,&nbsp;Michal Němec,&nbsp;Jan Šulc,&nbsp;Helena Jelínková,&nbsp;Katsumasa Iwai,&nbsp;Hiroyuki Takaku,&nbsp;Mitsonobu Miyagi","doi":"10.1007/s00340-025-08467-2","DOIUrl":"10.1007/s00340-025-08467-2","url":null,"abstract":"<div><p>A compact diode pumped Er:YLF laser emitting at wavelength 2825 nm was designed and constructed. Radiation delivery from this source by special hollow glass waveguides with inner diameters of 250, 320, 540, or 700 <span>(upmu)</span>m was investigated. The power transmission was up to 91% for around 1 m long waveguide. Measured hollow glass waveguide with this efficient transfer could serve as an appropriate solution of diode pumped mid infrared laser radiation delivery.</p></div>","PeriodicalId":474,"journal":{"name":"Applied Physics B","volume":"131 5","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00340-025-08467-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gravitational entropy in black hole transformations","authors":"Alan Alejandro Panuco Liñan,&nbsp;Daniela Pérez,&nbsp;Carlos Luna,&nbsp;Gustavo E. Romero","doi":"10.1140/epjc/s10052-025-14189-8","DOIUrl":"10.1140/epjc/s10052-025-14189-8","url":null,"abstract":"<div><p>There are several reasons to support the idea that entropy might be associated to gravity itself. In the absence of a quantum theory of gravity, classical estimators for the gravitational entropy have been proposed. Any viable description of the gravitational entropy should reproduce the Hawking–Bekenstein entropy at the event horizon of black holes. Furthermore, in any black hole transformation, these estimators must satisfy the second law of black hole thermodynamics. In this work, we analyze whether two entropy estimators, one based on the Weyl tensor and the other on the Bel–Robinson tensor, satisfy the second law in the transformation process from a Schwarzschild to a Reissner–Nordström black hole by the absorption of a charge test particle. We also address the inverse process. We show that depending whether the process is reversible or not, both estimators fulfill the second law.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 4","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14189-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of a nonlinear electromagnetic generalization of the Reissner–Nordström black hole","authors":"A. A. Araújo Filho","doi":"10.1140/epjc/s10052-025-14182-1","DOIUrl":"10.1140/epjc/s10052-025-14182-1","url":null,"abstract":"<div><p>In this work, we investigate the gravitational signatures of a nonlinear electromagnetic extension of the Reissner–Nordström solution. We conduct an analysis of light propagation, focusing on the photon sphere, shadow formation, and geodesic trajectories in this spacetime. The constraints on the parameter <span>(xi )</span>, which characterizes the nonlinear extension of the Reissner–Nordström black hole, are derived from observational data provided by the Event Horizon Telescope (EHT). The time delay effects are also considered. In the thermodynamic analysis, we examine the Hawking temperature, entropy, heat capacity, and the emission of Hawking radiation via the tunneling process. The remnant mass and evaporation time of the black hole at its final stage are estimated. In addition, we compute the quasinormal modes using the WKB approximation, taking into account the characteristic oscillations of the system under scalar, vector, and tensor perturbations. Additionally, the time-domain solution is analyzed for all these perturbations to examine their evolution over time.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 4","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14182-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum bit behavior of pinned fluxes on volume defects in superconductor","authors":"H. B. Lee,&nbsp;G. C. Kim,&nbsp;Byeong-Joo Kim,&nbsp;Young Jin Sohn,&nbsp;Y. C. Kim","doi":"10.1007/s00339-025-08506-x","DOIUrl":"10.1007/s00339-025-08506-x","url":null,"abstract":"<div><p>We studied a qubit based on flux-pinning effects in <span>(Delta H=Delta B)</span> region of a superconductor. In the state that volume defects are many enough in a superconductor, <span>(Delta)</span>H=<span>(Delta)</span>B region on M–H curve would be evolved, which is the region that increased applied magnetic field (<span>(Delta)</span>H) is the same as increasing magnetic induction (<span>(Delta)</span>B). Magnetization (M) is constant in the region by 4<span>(pi)</span>M = B - H. Here we show the behavior of fluxes in <span>(Delta)</span>H = <span>(Delta)</span>B region can be a candidate of qubit. Pinned fluxes on volume defects would move as a bundle in the region by repeating flux-pinning and pick-out depinning process from the surface to the center of the superconductor. During the process, magnetic fluxes would exist as one of states that are flux-pinning state at volume defects and depinning state from the defect. A difference of diamagnetic property occurs between pinning state at volume defects and depinning state from the volume defects. Thus, diamagnetic properties of the superconductor would oscillate in <span>(Delta)</span>H=<span>(Delta)</span>B region and the behavior would be observed in M-H curve. The oscillation can be used for a qubit by setting the pinning state at volume defects as <span>(mathinner {|{1}rangle })</span> and the depinning state as <span>(mathinner {|{0}rangle })</span>. It is determined that the operating temperature as a qubit is up to 25 K if <span>(hbox {MgB}_2)</span> is used as a base superconductor.</p></div>","PeriodicalId":473,"journal":{"name":"Applied Physics A","volume":"131 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Galaxy mergers in a fractal cosmology","authors":"Bruno J. Souza,&nbsp;Osvaldo L. Santos-Pereira,&nbsp;Marcelo B. Ribeiro","doi":"10.1140/epjc/s10052-025-14191-0","DOIUrl":"10.1140/epjc/s10052-025-14191-0","url":null,"abstract":"<div><p>This work discusses the influence of galaxy mergers in the evolution of a parabolic Lemaître–Tolman–Bondi (LTB) cosmology with simultaneous big bang endowed with two consecutive single fractal galaxy distributions systems possessing fractal dimension <i>D</i>. Based on recent empirical findings, it is assumed that the resulting galaxy mass from mergers can be expressed by a redshift dependent decaying power law. The proposed cosmological model modifies the relativistic fractal number counts distribution by including a merger rate evolution that estimates the model’s radial density. Numerical solutions for the first order small-merger-rate approximation (SMRA) are found and the results show that a fractal galaxy distribution having <span>(D=1.5)</span> in the range <span>(0.1&lt;z&lt;1.0)</span>, and <span>(D=0.5)</span> for <span>(1&lt;z&lt;6)</span>, as suggested by recent empirical findings, the SMRA allows consistent description of the model for a merger rate power law exponent up to <span>(q=0.2)</span> considering a fractal galaxy distribution starting from the Local Group. Consistent values were also found up to <span>(q=2.5)</span> and <span>(z=7)</span> from a scale smaller than the Local Supercluster. These results show that galaxy mergers can be successfully incorporated into the dynamics of a parabolic LTB fractal cosmology.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 4","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14191-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}