The European Physical Journal Plus最新文献

Pertussis recurrence is influenced by the interaction of vaccine-induced immunity, waning post-infection immunity, natural immune boosting, and secondary susceptibility. A six-compartment model is formulated using the difference–quotient representation of the conformable relaxation equation, with primary susceptible S, vaccinated V, infected I, recovered R, waning immunity W, and secondary-susceptible F populations. For differentiable state variables, the conformable operator is equivalent to an ordinary derivative under the nonlinear time transformation (u=t^alpha /alpha). Hence, the conformable order changes the timing of transient dynamics without altering the equilibrium equations or the reproduction threshold. Existence and uniqueness, non-negativity, boundedness, disease-free and endemic equilibria, the control reproduction number, and local stability are established. Two-parameter stability regions for the disease-free regime (mathscr {R}_{c}<1) and the endemic regime (mathscr {R}_{c}>1) are obtained numerically from the spectral abscissa of the corresponding Jacobian. A nonstandard finite difference (NSFD) scheme is then constructed using the DQR/ESDDFD denominator obtained from the conformable relaxation structure. The discrete scheme preserves non-negativity, while boundedness on finite computational intervals is established by mathematical induction. Numerical simulations for several conformable orders support the analytical threshold behavior: below the threshold, infection approaches the disease-free state, whereas above the threshold, the solution approaches a positive endemic state. The conformable order changes the transient time scale but not the limiting equilibrium coordinates. The analysis therefore provides a consistent link between conformable pertussis dynamics and structure-preserving numerical approximation.query{Please check the edit made in the article title.}

Historic textiles are a vital component of cultural heritage, reflecting identity, craftsmanship and the technologies of their time. Despite their significance, gaps remain in the understanding of textile degradation under indoor conditions, particularly in museum environments. This review synthesises current knowledge on the impact of indoor atmospheric conditions on two widely used natural fibres: cotton and silk. It examines fibre structure and the key mechanisms governing degradation, with particular emphasis on hydrolysis and oxidation. Interactions between multiple environmental stressors in museum atmospheres are discussed, highlighting coupled processes that can accelerate deterioration. The review introduces a structured distinction between mechanisms and a novel perspective on the role of particulate matter as a catalyst of textile alteration, underscores the importance of proxies and multimodal analytical approaches, and provides a critical discussion of transferring kinetic models to textiles. Finally, key knowledge gaps are identified, outlining priorities for future research aimed at mitigating complex degradation mechanisms in historic textiles.

This study provides detailed analyses of the thermodynamic properties of sodium clusters, focusing on their behavior as functions of cluster size and temperature. It is observed that the total internal energy (U) increases monotonically as the temperature (T) increases. This is because of the occupancy of numerous energy levels. Also, an increase in cluster size results in a more negative U. The entropy of clusters containing 34 and 58 atoms shows significant sensitivity to temperature, while clusters containing 20 and 40 exhibited less temperature sensitivity; this temperature-sensitive effect suggests a distinct behavior in clusters of different sizes. For higher temperatures (T > 0.2 eV), entropy increases linearly with temperature (S ~ 2aNT) with a level density parameter a = 11 Ry⁻¹, in agreement with results in previous studies. The electronic heat capacities of Na₃₄ and Na₅₈ exhibit well-defined peaks, while those of Na₂₀ and Na₄₀ show a continuous increase without distinct peaks. This size-dependent behavior reflects the different electronic structures of the sodium clusters. As the temperature increases, the internal energy changes rapidly, leading to a maximum heat capacity, followed by a decrease at higher temperatures as the system approaches the ideal gas state.

This paper establishes a novel bridge between differential geometry and topology by introducing the concepts of conditional retraction and conditional homotopy retract in the context of Reissner–Nordström wormhole spacetimes. We develop a rigorous mathematical framework that reveals previously unexplored topological properties of wormhole structures, demonstrating how these exotic spacetime configurations can be understood through the lens of modern homotopy theory. By analyzing the Lagrangian formulation of geodesics within the wormhole metric, we prove the existence of two distinct types of geodesic conditional retractions in four-dimensional Reissner–Nordström wormhole spacetime, each with unique topological characteristics. We extend these results to n-dimensional wormholes and establish a fundamental theorem showing that the limit chain of conditional retracts converges to a zero-dimensional wormhole spacetime, which provides fresh perspectives on the deep connection between dimensionality reduction and topological invariants in curved spacetimes. Furthermore, we demonstrate that while conditional retractions preserve certain homeomorphic properties, they exhibit asymmetric behavior under homeomorphisms, a finding with profound implications for understanding the fundamental structure of spacetime near singularities. These results advance our theoretical understanding of wormhole topology and also provide a mathematical foundation for exploring quantum gravitational effects in highly curved spacetimes, potentially offering new approaches to resolving the information paradox in black hole physics.

We construct models for first- and second-order Fermi acceleration of particles, incorporating generic frame transformations, dispersion relations, and conservation laws. Within this framework, we study deformations of Lorentz symmetry via the (kappa )-Poincaré algebra in the bicrossproduct and classical bases, which, respectively, deform and preserve the relativistic dispersion relation. We also examine explicit Lorentz symmetry violation and compare the results with deformed relativity and special relativity. The energy spectra present different shapes when one considers deformation or violation of Lorentz symmetry in superluminal or subluminal scenarios. One of the possible outcomes is an intense decay of the spectrum for higher energies. We also gather the predictions of all the scenarios considered, comparing the spectra produced at the source in the energy domain, which is the variable in which cosmic ray observatories report their measurements.

We construct static, anisotropic compact-star configurations in Rastall gravity using the Finch–Skea metric ansatz and investigate how the Rastall coupling modifies the structure and stability of ultra-dense matter. We systematically analyze the dependence of the energy density, pressures, anisotropy, compactness, and gravitational redshift on the Rastall parameter, with the general relativity (GR) limit recovered when the coupling vanishes. The resulting mass–radius and moment of inertia–mass relations show that the Rastall modification can increase both the maximum mass and the corresponding moment of inertia relative to the GR configurations. We further compare the predicted maximum mass and moment of inertia with the observational constraints for neutron-star candidates, including PSR J0437–4715, PSR J2222–0137, and PSR J0348+0432, and examine the extent to which the model accommodates the corresponding astrophysically inferred properties. The physical admissibility of the configurations is assessed through the standard energy conditions, causality, the adiabatic-index criterion, the generalized Tolman–Oppenheimer–Volkoff equilibrium equation, and the Herrera cracking condition. Our results indicate that the Rastall coupling provides a systematic modification of the maximum mass, compactness, and rotational properties of anisotropic compact stars while preserving the required physical and stability conditions over the parameter range considered. These results demonstrate that Rastall gravity can provide a viable modified-gravity framework for exploring the structure of ultra-dense compact objects beyond general relativity.

Y/B-codoped ZnO nanoparticles (NPs), with a nominal composition of Zn_0.95−xB_0.05Y_xO (x = 0.00–0.05), were synthesized using the sol–gel method to study the effects of defects on their optical and antibacterial properties. Structural characterization through X-ray diffraction confirmed that all samples crystallize in the hexagonal wurtzite structure, with lattice distortions assessed via variations in the c/a ratio. The type and density of defects, along with crystal quality, were systematically analyzed using photoluminescence (PL) spectroscopy and positron annihilation lifetime spectroscopy (PALS). Optical absorption measurements were conducted using a Shimadzu UV-2600 spectrophotometer. The optical band gaps were determined, and refractive indices were calculated utilizing five different theoretical models. The results show a nonmonotonic variation in the optical band gap with Y content, peaking at 3.262 eV when x = 0.02. In contrast, the refractive index exhibits little dependence on Y concentration, despite oscillatory lattice strain, which is tensile at maximum strain and compressive at minima. An increase in Urbach energy with dopant concentration indicates greater structural disorder and the presence of defect-induced band-tail states. PL analysis reveals both acceptor-type (A⁰(V_Zn)) and donor-type (V_O, D⁰(Znᵢ)) defects, with their increasing concentrations contributing to band gap narrowing and enhanced band-edge tailing. Y/B codoping allows for the controlled modification of lattice parameters, defect populations, and optical responses while maintaining the structural integrity of wurtzite ZnO. Additionally, the Y/B-codoped ZnO NPs demonstrate significant antibacterial activity against Staphylococcus aureus, whereas no notable activity is observed against Escherichia coli. This antibacterial effect is primarily attributed to the generation of reactive oxygen species (ROS) mediated by oxygen vacancies, rather than by particle-size effects.

Particles in high-density quantum plasmas exhibit several quantum mechanical corrections that modify their governing fluid equations. These include the Bohm potential, arising from quantum diffraction and tunneling, and the exchange-correlation potential, originating from Pauli exclusion principle and Coulomb interactions among fermions such as electrons and positrons. In this work, we investigate positron-acoustic solitary waves (PASWs) in a plasma system consisting of relativistically degenerate electron and positron fluids and static ions. We simultaneously incorporate the Bohm potential and exchange-correlation effects into Lorentz-factor-dependent fluid equations within the quantum hydrodynamic framework. We employ the reductive perturbation method with stretched coordinates incorporating the Lorentz factor of the wave frame to derive the Korteweg–de Vries equation and investigate the evolution of PASWs. Numerical parametric analysis reveals that the combination of the Bohm quantum potential and the exchange-correlation function significantly modifies the nonlinear and dispersive behavior of plasma waves. Consequently, we find that the Bohm potential primarily governs the dispersive properties, while the exchange-correlation function affects both the electrostatic potential and amplitude of the solitary waves. The findings of this study can contribute to the understanding of the nonlinear waves in dense degenerate quantum plasma, with potential applications to compact astrophysical environments such as white dwarfs.

Recently Ahmadov et al. obtained an analytical bound-state energy expression for the generalized tanh-shaped hyperbolic potential using the Nikiforov–Uvarov method together with a Pekeris approximation to the centrifugal term. In this Comment, we examine the numerical spectrum reported by Ahmadov et al. in Table 1 of their paper. Three issues are identified. First, sixteen of the tabulated energies lie below the minimum of the potential or of the corresponding effective potential obtained after the Pekeris approximation and therefore cannot represent bound-state eigenvalues. Second, direct substitution into the derived energy expression reproduces the reported (s)-state values but not the (l>0) entries. The quantum-number notation used by the authors in Table 1 is also inconsistent with their statement that (n) is the radial quantum number. The (s)-wave finite-state condition additionally excludes the (5text{s}) value reported for the third parameter set. Third, comparison with a direct numerical integration of the original radial Schrödinger equation shows that the analytical expression is very accurate for small (alpha ), whereas the agreement becomes poorer as (alpha ) increases, particularly for states with larger (l).

We present a reduced-order, fully dimensionless thermo–fluid model describing pressure-driven extraction in a moka pot. The system is formulated as a minimal set of coupled nonlinear ordinary differential equations capturing heating, vapor-pressure generation, and threshold-driven flow through a porous medium. The model exhibits distinct dynamical regimes governed by a small number of physically interpretable dimensionless parameters, including delayed extraction, smooth extraction, and rapid-flow behavior arising from nonlinear feedback. The model is calibrated and quantitatively validated against digitized experimental measurements of pressure and cumulative extraction, while the temperature evolution provides an independent experimental assessment of the thermal scaling of the reduced model. Despite its simplicity, the model captures the essential thermo–fluid coupling responsible for self-regulating extraction dynamics in confined systems and provides a transparent framework for analyzing threshold-driven flow phenomena.