The European Physical Journal Plus最新文献

{"title":"Multi-component sigmoidal modeling of cumulative COVID-19 mortality in Colombia: logistic, Gompertz, and Boltzmann-type formulations","authors":"Ubaldo Yancachajlla Tito","doi":"10.1140/epjp/s13360-026-08427-5","DOIUrl":"10.1140/epjp/s13360-026-08427-5","url":null,"abstract":"<div><p>National COVID-19 mortality records combine several growth phases that cannot be represented adequately by a single sigmoid. We developed a multi-component framework for cumulative deaths in Colombia using logistic, Gompertz, and Boltzmann-type formulations. Country-level mortality data were derived from the Johns Hopkins University Center for Systems Science and Engineering COVID-19 repository and comprised 1143 daily observations from 22 January 2020 to 9 March 2023, ending at 142,339 cumulative deaths. An initial component count was estimated from peaks in a seven-day-smoothed daily series, after which orders <span>(m=1,ldots ,10)</span> were fitted by bounded nonlinear least squares with multiple initializations. Thus, model-order selection was automatic within a prespecified candidate range. The best in-sample representation was a ten-component Boltzmann-type model, implemented here as a logistic mixture with a global baseline. It achieved <span>(R^2=0.99999897)</span>, RMSE <span>(=56.54)</span> deaths, MAE <span>(=42.30)</span>, and BIC <span>(=9442.23)</span>. The ordinary logistic mixture was competitive (<span>(Delta textrm{BIC}=6.97)</span>), whereas Gompertz was less accurate. On the daily-death scale, the selected derivative achieved <span>(R^2=0.9610)</span> and RMSE <span>(=31.77)</span> deaths/day. Residual autocorrelation remained substantial and the selected order reached the upper search boundary. The fitted terms are therefore interpreted as mathematical mortality-growth components rather than ten confirmed epidemiological waves.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149309939","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":"The promise of gravitational-wave astronomy","authors":"Parameswaran Ajith","doi":"10.1140/epjp/s13360-026-08488-6","DOIUrl":"10.1140/epjp/s13360-026-08488-6","url":null,"abstract":"<div><p>We review the promise of upcoming gravitational-wave (GW) observations in addressing some of the important open questions in astrophysics and cosmology. A decade after the first direct detection of GWs, the field is entering a transformative phase driven by progressive detector upgrades and the anticipated advent of space-based and next-generation ground-based observatories. These instruments will not only push the distance horizon of GW observations to cosmological redshifts, but will dramatically extend the accessible frequency band, opening entirely new source classes that lie beyond the reach of current detectors. The source landscape is rich enough that surprises are likely. This review surveys our current understanding across this landscape and offers some perspective on the discoveries that upcoming GW observations are poised to deliver.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149309941","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":"Thermodynamic cost of regeneration in a quantum Stirling cycle","authors":"Ferdi Altintas","doi":"10.1140/epjp/s13360-026-08467-x","DOIUrl":"10.1140/epjp/s13360-026-08467-x","url":null,"abstract":"<div><p>We study the standard four-stroke regenerative quantum Stirling heat-engine cycle, which assumes thermal equilibrium at the four endpoints, within the standard weak-coupling, Markovian open quantum system framework. We point out that the regeneration process is not thermodynamically free in a reduced open-system description, and we treat the required work input as an explicit regeneration cost by modifying the cycle efficiency accordingly. We consider two working substances—a single spin-1/2 and a pair of interacting spin-1/2 particles—and investigate the cycle performance by taking the regeneration cost at its minimum value set by the Carnot heat-pump limit. For comparison, we also analyze the conventional Stirling cycle without regeneration under the same conditions. The super-Carnot efficiencies reported under the cost-free regeneration assumption disappear once the regeneration cost is included: The modified efficiency stays below the Carnot bound, while still remaining higher than the efficiency of the conventional Stirling cycle. For the conventional Stirling cycle, we provide a rigorous Carnot bound using quantum relative entropy, whereas for the regenerative cycle we derive a sufficient lower bound on the regeneration cost that guarantees thermodynamic consistency. Finally, we suggest three candidate quantum regenerator models for future work.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 11","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149309940","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":"Phoretic interactions in two-medium wedge geometries","authors":"Abdallah Daddi-Moussa-Ider","doi":"10.1140/epjp/s13360-026-08477-9","DOIUrl":"10.1140/epjp/s13360-026-08477-9","url":null,"abstract":"<p>We investigate the diffusiophoretic motion of a chemically isotropic active colloid in a three-dimensional wedge formed by two distinct fluid media, in the limit of vanishing Péclet and Reynolds numbers. The concentration field is obtained using the Fourier–Kontorovich–Lebedev transform, yielding an exact representation for arbitrary wedge opening angles and interfacial contrasts. We introduce the interfacial parameter <span>(Gamma =(1-lambda ell )/(1+lambda ell ))</span>, where <span>(lambda)</span> denotes the diffusivity contrast and <span>(ell)</span> the solute partition coefficient. For <span>(Gamma =pm 1)</span> and commensurate wedge angles, the solution reduces to finite image constructions, with distinct structures for even and odd commensurability. The general solution also recovers the planar-interface and semi-infinite-interface limits. The leading-order translational phoretic velocity is derived from the concentration field, revealing a strong interplay between wedge geometry and interfacial properties that governs both the magnitude and direction of particle motion. This work provides a framework for understanding and controlling phoretic transport in confined multiphase environments and offer a basis for extensions to finite-size geometries and mixed fluid–fluid and solid boundary conditions. Our results may find applications in the control of active-particle transport in confined multiphase environments, where interfacial properties and geometry can be exploited to tune phoretic motion.</p>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjp/s13360-026-08477-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339568","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":"Pattern formation in GMC protein–lipid interactions driven by turing instability and membrane inhomogeneities","authors":"E. R. Amougui Mebara,&nbsp;R. Y. Ondoua,&nbsp;J. C. Mimshe Fewu,&nbsp;D. Belobo Belobo,&nbsp;H. P. Ekobena Fouda","doi":"10.1140/epjp/s13360-026-08263-7","DOIUrl":"10.1140/epjp/s13360-026-08263-7","url":null,"abstract":"<div><p> In this work we investigate the influence of inhomogeneities on pattern formation within Glucose–Methanol–Choline (GMC) protein–lipid interactions. For this purpose, we elaborate on a three-variable reaction–diffusion model allowing space-dependent adsorption rate of the unphosphorylated proteins on the membrane, hereby inducing inhomogeneities. The Turing’s method permits to identify the instability criterion which states that the ratio of the cytosol on membrane diffusion coefficients must be larger than 0.38. Intensive numerical simulations allow to unveil the role of two types of inhomogeneities on the generation of patterns. A localized inhomogeneity favors the appearance of spots, which aggregate around the center of the inhomogeneity at relatively longer times. In the presence of a periodic inhomogeneity, cluster-like patterns pop up that evolve to form symmetric structures with respect to the center of the domain at relatively longer times. Quantitative measurements based on Fourier transform analysis and peak detection provide characteristic wavelengths, exponential growth rates, spot densities, and average spot sizes. Our results, though in line with protein aggregates and lipids rafts in biological membranes, single out as induced by inhomogeneities unlike previous studies. We believe that the current work paves the way for future investigation of the effect of inhomogeneities within the protein–lipid interactions medium.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339285","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":"Josephson oscillation and nonlinear self-trapping in quasi-one-dimensional quantum liquid","authors":"Shivam Singh,&nbsp; Ibrar,&nbsp;Suhail Rashid,&nbsp;Ayan Khan","doi":"10.1140/epjp/s13360-026-08473-z","DOIUrl":"10.1140/epjp/s13360-026-08473-z","url":null,"abstract":"<div><p>In this article, we study the two-mode method to analyze the Josephson oscillation for a trapped binary Bose-Einstein condensate while taking into account the beyond mean-field and three body interactions. For this purpose, we use the archetypal model of double well potential and study the Josephson oscillation and self-trapping phases in quasi-one dimension. Additionally, our analysis provides quantitative discussion on the effect of asymmetry and dimension. We further corroborate our findings with Bogoliubov quasi-particle method and notice the existence of roton-like mode.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339284","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":"Does a weighted-peak index below unity ensure safety for bearers of cardiac implantable electronic medical devices? A weighted-peak analysis of the ISO 14117 immunity test signals","authors":"Eugenio Mattei,&nbsp;Cecilia Vivarelli,&nbsp;Giovanni Calcagnini,&nbsp;Nicola Zoppetti","doi":"10.1140/epjp/s13360-026-08443-5","DOIUrl":"10.1140/epjp/s13360-026-08443-5","url":null,"abstract":"<div><p>International standards governing the electromagnetic compatibility (EMC) of cardiac implantable electronic devices (CIEDs) link the immunity levels of cardiac pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs) to the exposure limits recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). If the general-public reference levels (without time averaging) are not exceeded, the CIEDs are expected to work uninfluenced, and thus, the exposure can be considered to pose a low risk. However, the ICNIRP reference levels are root-mean-square (RMS) quantities defined for single-frequency sinusoidal fields. In case of non-sinusoidal and multifrequency exposures, the weighted-peak (WP) index is the reference procedure used in practical compliance assessment. Whether a WP value below unity implies exposure conditions less severe than those represented by CIED immunity test is still an open question. In this work, we reconstruct the equivalent magnetic field that would induce the ISO 14117:2019 immunity-test signals and we compute the weighted-peak index of these waveforms over the range 16.6 Hz–10 MHz, against the ICNIRP 1998 general-public reference levels. The analysis is performed both in the time domain (digital IIR weighting filter reproducing the gain of a Narda ELT-400 probe) and in the frequency domain (FFT). The weighted-peak index is found to fall below 1 in two frequency ranges: around 1 kHz and above 800 kHz. This shows that satisfying the WP threshold of 1 does not, by itself, guarantee the absence of interference risk for PM/ICD users in those frequency ranges. Given the WP obtained by our analysis, a practical and conservative approach would be to lower the threshold of WP to 0.6 when the risk analysis includes CIEDs.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339487","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":"Dynamical instability of expansion-free cylindrical spacetime in matter–geometry coupled gravity theory","authors":"M. Sharif,&nbsp;Tayyab Naseer,&nbsp;Arooj Fatima","doi":"10.1140/epjp/s13360-026-08462-2","DOIUrl":"10.1140/epjp/s13360-026-08462-2","url":null,"abstract":"<div><p>This study examines the dynamical instability in cylindrical fluid configuration undergoing non-expanding evolution within the framework of a matter–geometry coupled gravitational theory. A perturbation scheme is initially employed to derive the dynamical equations governing the system’s evolution and to analyze the stability across the Newtonian, post-Newtonian, and post-post-Newtonian regimes. These results indicate that the adiabatic index fails to play any role for stability within the standard Newtonian or post-Newtonian approximations. Our results indicate that the instability region is instead dictated by alternative parameters, which exhibit strong agreement with earlier investigations into self-gravitating collapse. We also use junction conditions to smoothly match the interior spacetime with a suitable exterior line element. We conclude that the dynamics of the cylindrical fluid configuration under consideration are primarily dictated by key physical quantities, namely, the energy density and the principal (radial, tangential, and axial) stresses.\u0000</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339488","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":"Holographic (s)- and (p)-wave superconductors from the (4D) regularization of Einstein–Lovelock theory","authors":"Soodeh Zarepour,&nbsp;Ali Dehghani","doi":"10.1140/epjp/s13360-026-08480-0","DOIUrl":"10.1140/epjp/s13360-026-08480-0","url":null,"abstract":"&lt;div&gt;&lt;p&gt;We investigate holographically dual descriptions of &lt;span&gt;((2+1))&lt;/span&gt;-dimensional &lt;i&gt;s&lt;/i&gt;-wave and &lt;i&gt;p&lt;/i&gt;-wave superconductors in the framework of four-dimensional 4&lt;i&gt;D&lt;/i&gt; regularization of Einstein–Lovelock gravity theories, incorporating higher curvature corrections beyond the Gauss–Bonnet sector. We first implement the 4&lt;i&gt;D&lt;/i&gt; regularization of Einstein–Lovelock gravity with finely tuned coupling constants to include corrections up to any &lt;i&gt;K&lt;/i&gt;th order in curvature. The bulk geometry is constructed from exact black brane solutions characterized by the fine-tuned Lovelock coupling &lt;span&gt;(alpha)&lt;/span&gt; and the highest power of curvature in the Lagrangian &lt;i&gt;K&lt;/i&gt;, allowing systematic control over higher curvature effects. We then analyze the condensation of scalar and vector operators dual to minimally coupled matter fields, focusing on two possible prescriptions for fixing the bulk field masses. We show that these choices play a nontrivial role in determining both quantitative and qualitative features of the superconducting phase. Our results demonstrate that higher curvature terms significantly modify the phase structure of both &lt;i&gt;s&lt;/i&gt;-wave and &lt;i&gt;p&lt;/i&gt;-wave systems and enhance the sensitivity of the condensates and critical temperatures to the gravitational couplings. In both cases, the critical temperature generally increases with the maximal curvature order &lt;i&gt;K&lt;/i&gt;, leading to higher-&lt;span&gt;(T_c)&lt;/span&gt; phases compared to Einstein gravity, particularly for negative values of the fine-tuned Lovelock coupling. This enhancement is typically accompanied by a suppression of the condensate at low temperatures. The fine-tuned coupling &lt;span&gt;(alpha)&lt;/span&gt; effectively governs the strength of higher curvature interactions in the bulk, acting as a geometric control parameter for superconductivity: positive &lt;span&gt;(alpha)&lt;/span&gt; suppresses condensation and lowers &lt;span&gt;(T_c)&lt;/span&gt;, whereas negative &lt;span&gt;(alpha)&lt;/span&gt; enhances superconducting order and promotes higher-&lt;span&gt;(T_c)&lt;/span&gt; phases relative to Einstein gravity. We further study the optical conductivity and find that both the gap frequency and the ratio &lt;span&gt;(omega _g/T_c)&lt;/span&gt; exhibit a strong dependence on the Lovelock coupling &lt;span&gt;(alpha)&lt;/span&gt; and the curvature order &lt;i&gt;K&lt;/i&gt;, deviating from the universal Einstein gravity result. In particular, higher curvature effects enhance the superconducting gap scale, while preserving the expected large-frequency asymptotics and the divergent DC conductivity. Despite these modifications, all condensates display mean-field scaling near the critical temperature, consistent with a second-order phase transition. Notably, the &lt;i&gt;p&lt;/i&gt;-wave system shows a stronger sensitivity to the mass-fixing prescription compared to the &lt;i&gt;s&lt;/i&gt;-wave case, indicating a richer dependence on the effective AdS scale. Overall, higher curvature corrections in the 4&lt;i&gt;D&lt;/i&gt; regularization of Einstein–Lovelock gravity theories provide a robust ","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339287","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":"Learning the nonlinear soliton dynamics of microtubules with physics-informed neural networks and neural operators","authors":"Mohammad Akram,&nbsp;Umar Ishtiaq,&nbsp;Ioan-Lucian Popa","doi":"10.1140/epjp/s13360-026-08484-w","DOIUrl":"10.1140/epjp/s13360-026-08484-w","url":null,"abstract":"<div><p>The nonlinear electromechanical dynamics of microtubules is described by a damped and driven <span>(phi ^4)</span> nonlinear Klein–Gordon equation known as the <i>u</i>-model. This paper couples that physical model with three learning tasks and validates each of them against exact theory. Starting from the discrete protofilament Hamiltonian, we derive the governing partial differential equation, relate its coefficients to measured properties of the tubulin dimer, construct its kink soliton in closed form and establish the energy balance and modulation instability relations that constrain the learning problems. A physics-informed neural network solves the field equation and the inverse problem of parameter identification, and a Fisher information analysis separates the parameters that the data determine from those they do not. A neural operator learns the parametric solution map, which yields a learned phase diagram and a Gaussian process design of solitons. Sparse identification of nonlinear dynamics recovers the governing law from trajectory data, and its sensitivity to noise is quantified. A finite-difference reference solver, validated against the exact soliton to a relative error near <span>(3.6times 10^{-4})</span>, supplies the training data, serves as the conventional benchmark against which the accuracy, training cost and convergence of each learning stage are measured, and allows the study to proceed in regimes without closed form, among them soliton collisions and inhomogeneous media. The results connect coherent energy and information transport along microtubules to reproducible and identifiable learning models.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"141 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339345","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}