Revista Mexicana de Física

Emergent symmetry breaking during the foraging collective activity by ants

Ana Luisa Ballinas-Hernández — 2026-01-01

This study analyzes a system of nonlinear differential equations associated with the number of foraging ants visiting two identical exploitation sources in a static environment. Steady-state solutions correspond to establishing pheromone trails sustained after the colony density reaches a critical size. In the quasi-steady-state approximation, the model reduces to a single-variable symmetry description. After including additive white noise perturbations, the scheme becomes a Langevin equation. Solutions to this equation suggest that the processes underlying the collective task are associated with an order (recruitment-abandonment) - disorder (successful exploration) parameter that varies as a rational homographic function concerning the control parameter of the model. We find that intrinsic random disturbances, produced by successful foragers, break the symmetry of an equal number of ants in each option, leading to preferential visits to one of the two food sources. We also observe that the behavior of the order-disorder parameter strongly depends on changes in the colony size. In general, the stability of consensus in collective decision-making increases with increasing noise intensity.

A numerical study on regularization and key rheological parameters in the evolution of rigid zones in Herschel–Bulkley fluids

Messaouda Elalem — 2026-01-01

Regulating the formation of rigid zones in viscoplastic fluids is essential for accurate numerical modeling and practical applications. This paper presents a numerical study on the control and minimization of rigid zones in Herschel–Bulkley fluids during flow at the yield stress threshold within a confined square domain. The Papanastasiou regularization method is employed to ensure a smooth transition between fluid and rigid-like zones. This study systematically analyzes the influence of key rheological parameters and the regularization approach on the suppression and reduction of these zones. The influence of the regularization parameter on rigid zone formation during flow is investigated, along with the effect of the critical shear rate for different values of this parameter. Additionally, the impact of inlet pressure on the rigid zone area is examined, followed by an in-depth analysis of its effect for various critical shear rate values to explore their combined influence. Furthermore, the study explores the influence of the consistency factor and the power-law index on rigid zones during flow. The findings highlight optimal parameter selection strategies to suppress or minimize rigid zones at the yield stress threshold, ensuring improved numerical accuracy in viscoplastic fluid simulations.

Approximate solutions and thermodynamic properties of a potential model

Clement Onate — 2026-01-01

The solution of the radial Schrödinger equation for a Pὃschl-Teller type of potential with two main parameters is obtained via the supersymmetric approach. The energy equation and its corresponding wave function are obtained explicitly. The energy equation obtained was used to calculate the partition function via the Poisson summation formula. The calculated partition was used to studied the enthalpy, Gibbs free energy and entropy of the system. The result obtained showed that the two parameters have the same effect on the energy of the system but different effects on the thermodynamic properties. It was also shown that the rise in temperature of the system only increases enthalpy but decreases partition function, Gibbs free energy an entropy.

Electronic and thermoelectric properties of AgBi₃Se₅ and AgBi₃S₅ materials: A first-principles study

Tomas Santillan Gomez — 2026-01-01

In this work, the structural, electronic, and thermoelectric properties of the thermoelectric materials AgBi₃S₅ and AgBi₃Se₅ were calculated using Density Functional Theory (DFT). The aim was to determine the total and partial density of states, the Seebeck coefficient, electrical conductivity, thermal conductivity, and the figure of merit for both systems. The electronic properties were studied using the modified Becke-Johnson Tran-Blaha (TB-mBJ) potential (2009) for the exchange-correlation potential. The analysis of the electronic properties shows that the total density of states of AgBi₃S₅ and AgBi₃Se₅ are similar near the Fermi energy. In general, both materials exhibit comparable characteristics, with some higher peaks below the Fermi energy, primarily due to the partial density of states of the Se atoms. The Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit of AgBi₃S₅ align with experimental results. Meanwhile, AgBi₃Se₅ exhibits higher figure of merit values in the temperature range of 500 to 800 K, where it also shows an improved Seebeck coefficient. The highest figure of merit value obtained was 0.441 for AgBi₃Se₅ at a temperature of 800 K.

Optimizing energy conversion in a PV-TGS (mSi–Bi₂Te₃) using numerical simulation of semiconductors materials

Demetrio Fuentes-Hernández — 2026-01-01

A numerical simulation model based on the energy transfer and conversion by the semiconductor materials of a Photovoltaic-Thermoelectric Generation System (PV-TGS) was developed to determine its theoretical power. The model yielded results that differed from those previously reported by other authors for PV panels and cells by a range of -0.017% to +1.74%. In thermoelectric production, the results deviated by a range of -2.27% to -2.80%. The model was formulated based on the constitutive equations of the phenomena inherent to the photovoltaic generation of a monocrystalline silicon PV panel (mSi) and the thermoelectric generation of bismuth telluride (Bi₂Te₃) Thermoelectric Generators (TEG). The primary variables of interest were irradiance (G), panel operating temperature (T_PPV), and the cold section of the TEG (T_c), as well as the generated electrical power (P). The research outcomes enabled the identification of the optimal number of TEGs for the design of a PV-TGS. This determination was derived by considering the temperature differential between the T_PPV and T_c sections, as well as the generation efficiency of PV-TGS as a function of incident radiation. Consequently, a pair of equations was formulated that establish a direct correlation between the thermoelectric generation rate and the desired output power.

U-Net segmentation of the kidney on noncontrast CT for kidney stones location: a deep learning model for Mexican patients

Luis Pérez — 2026-01-01

This work presents the implementation of convolutional neural networks for the automated detection and segmentation of kidney stones in non-contrast computed tomography (CT) medical images from patients of the Mexican Institute of Social Security (IMSS). A U-Net architecture was employed to segment the kidneys and delineate regions of interest in high-resolution CT slices, with ground truth annotations provided by medical specialists. The model was trained and validated on a curated dataset representative of the Mexican population, achieving a Dice similarity coefficient of 0.9808 ± 0.038, an IoU of 0.9623 ± 0.0073, and a validation loss of 0.0040 ± 0.008 in five-fold crossvalidation. The proposed system demonstrated rapid convergence and excellent agreement with manual segmentations, confirming its utility as a reliable diagnostic aid for kidney stone detection in clinical practice.

Exploring direct band gap engineering in chloro-elpasolite Cs2BInCl6 (B=Ag and Au): A comprehensive study of structural, elastic, optoelectronic and thermoelectric properties

Noureddine MECHEHOUD — 2026-01-01

In this investigation, an analysis was conducted on the stability, structural, electronic, optical, and thermoelectric properties of the halide double perovskites (HDPs) Cs₂BInCl₆ where B=Ag and Au. Applying the FP-LAPW approach, which is a subset of density functional theory (DFT), the study was performed employing the Wien2k code package. The most stable configuration corresponds to the cubic Fm͞3m (N°225) symmetry in a nonmagnetic (NM) state, as determined through the analysis of optimal structural parameters for both materials. The examination of the electronic features illustrates a semiconductor behavior characterized by a direct band gap at the Γ-Γ direction, with values of 3.245 eV for Cs₂AgInCl₆ and 2.052 eV for Cs₂AuInCl₆, closely mirroring experimental observations. The optical computations demonstrate an absorption coefficient within the visible spectrum that is almost zero and exceeding 1.6x10⁴ cm^-1 in the Extreme Ultraviolet (EUV) range. Moreover, the high reflectivity of the materials, reaching a peak of 55% for Cs₂AgInCl₆ and 40% for Cs₂AuInCl₆ at 17.5eV (70.85 nm) in EUV region, indicates a promising potential for utilization in optoelectronics, particularly in the UV and EUV sectors. Additionally, the assessment of thermoelectric performance involved the computation of thermoelectric properties. Both perovskites exhibit elevated electrical conductivity, low thermal conductivity, an increased Seebeck coefficient, and a higher figure of merit, positioning them as favorable candidates for thermoelectric applications.

Investigations of physical properties of the new EuMnCu2P2 compound

Bahmad — 2026-01-01

This work explored the EuMnCu₂P₂ compound, examining its diverse physical properties, including structural, electronic, optical, and thermoelectric properties. The investigation used density functional theory (DFT) implemented in the Wien2k package. The GGA-PBE approach was employed to determine the exchange-correlation potential, with consideration for spin-orbit coupling (SOC). The results on structural properties of the EuMnCu₂P₂ compound indicate that the stable ground state of the compound is the ferromagnetic (FM) phase. Additionally, our electronic findings indicate the metallic behavior of the EuMnCu₂P₂ compound. We have examined several key parameters in assessing optical properties, such as electron energy loss, absorption coefficient, real and imaginary dielectric tensors and optical conductivity. These properties provide valuable insights into how the material interacts with light and electromagnetic radiation. A significant finding in this study is that the compound exhibits exceptional absorption capabilities within the low and medium ultraviolet (UV) spectrums. This strong absorption in the UV region can be attributed to the material's unique electronic structure and response to the incident light. The excellent absorption properties make the compound a potential candidate for various applications in optoelectronics, photonic devices, and even solar energy conversion, where efficient utilization of UV light is crucial. Furthermore, we investigated the thermoelectric properties. Our findings reveal that the Seebeck coefficient decreases with increasing temperature, irrespective of the spin channel. The results suggest that the material displays an n-type behavior, as indicated by the negative values of the Seebeck coefficient. To gain a comprehensive understanding of the thermoelectric behavior of the alloy for practical applications.

Synthesis, differential thermal analysis, and crystal structure of the quaternary chalcogenide compound Cu2FeGeTe4

Gerzon E. Delgado — 2026-01-01

This study reports on the quaternary diamond-like semiconductor copper iron germanium tellurium, Cu₂FeGeTe₄. The material was synthesized using the melt and annealing technique by directly reacting the elements. The thermal behavior of the Cu₂FeGeTe₄ compound was investigated using thermogravimetric analysis. The Rietveld refinement method characterized the crystal structure through X-ray powder diffraction. The powder diffraction pattern revealed that the principal phase, Cu₂FeGeTe₄, constituted 85.4%, while the secondary phase, FeTe₂, accounted for 14.6%. The quaternary chalcogenide compound Cu₂FeGeTe₄ belongs to the I₂-II-IV-VI₄ system and crystallizes in the stannite structure within the non-centrosymmetric tetragonal space group I-42m (Nº 121), Z= 2, with unit cell parameters a= 5.9293(8) Å, c= 11.9239(8) Å, V= 419.20(2) Å³. Its structure consists of a three-dimensional close-packed arrangement of slightly distorted CuTe₄, FeTe₄, and GeTe₄ tetrahedra, interconnected through shared faces and corners. The chemical structure was verified through Bond Valence Sum (BVS) calculations

Electric current from Schwinger’s time-ordered propagator

Cristian Villavicencio — 2026-01-01

The quasistatic electric current density of fermions in the presence of an external electric field is determined through the utilization of a time-ordered Schwinger propagator. The study encompasses the necessary conditions for establishing a well-defined time-ordered propagator within the Schwinger formalism, specifically concentrating on constant and uniform electromagnetic fields. Within this theoretical framework, a chemical potential is introduced, resulting in non-zero values for the electric current and charge number density. Consequently, the dependence of electric conductivity on the strength of the electric field and the charge number density is investigated.

Multiplicity dependence of the entropy and heat capacity for pp collisions at LHC energies

Carlos Munguía — 2026-01-01

We investigate the multiplicity dependence of the transverse momentum spectrum of the charged particle production in pp collisions at LHC energies. To this end, we consider the experimental data classified with different multiplicity estimators, defined by the ALICE Collaboration, that are analyzed under the picture of the nonextensive particle production. We compute the variance, kurtosis, Shannon entropy, and heat capacity of the $p_T$ spectrum to study the hardening process as a function of the multiplicity and temperature under the different event classifiers. We found that both the Shannon entropy and the heat capacity show different responses for the triggers at the forward-backward and midrapidity regions. We emphasize that the selection of event biases may induce different responses in estimating theoretical and phenomenological observables that could lead to misleading conclusions.

Multiplicative calculus in optical fiber analysis: an alternative frame perspective

Anıl Altınkaya — 2026-01-01

This work uses the techniques of a non-Newtonian calculus (or multiplicative calculus) in the 3D Riemannian manifold to investigate the geometric features of linearly polarized light waves along optical fibers using the alternative moving frame. The evolution of a linearly polarized light wave is linked to a geometric phase since the optical fiber is thought to be a one-dimensional object embedded in a 3D Riemannian manifold. Thus, we produce a novel kind of multiplicative derivative geometric phase model. Furthermore, we present magnetic curves that are produced by the electric field E, defined by the electromagnetic curve. Then we define the Rytov curve, which consists of the combination of the space curve and the electromagnetic curve. In conclusion, we gave examples that match the theory and visualized them using the MATLAB program and analyzed the results using multiplicative calculus, which allows us to interpret the results proportionally.

Temperature sensing using micro-deformed looped fiber taper

Luis Fernando Enríquez Gómez — 2026-01-01

A novel fiber-optic temperature sensor device based on an optical fiber tapered loop with a micro-deformation at the taper waist section to enhance its sensitivity is presented. The taper waist diameter was selected as 10 mm, and the micro-deformation at the taper waist section enables the formation of spectral deep notches with enhanced sensitivity to external disturbances, such as temperature. Three dissimilar looped devices were fabricated to assess the effectiveness of engaging temperature disturbances ranging from 100 °C to 600°C. It was found that a bi-dose function fits better the wavelength-shift response to temperature changes of the enhanced spectral notches as a function of temperature, with greater R² values, in contrast with a linear fitting. By using a linear fitting for the whole range of temperatures, the results show a range of average linear sensitivity from approximately 7.39 pm/°C to 17.07 pm/°C. With these discoveries, the proposed device can be used as a high-temperature sensor in a wide range, which makes it attractive for practical applications. The encouraging results obtained in this article contribute significantly to the field of fiber optic high-temperature sensors and have a lot of potential to be used in industry and research.

A note on stability of traveling waves in a Q-switched fiber laser

Mohammad Reza Rahmati — 2026-01-01

This study presents a unified theoretical and experimental framework for ensuring stable, high-repetition–rate operation in passively Qswitched hybrid thulium/erbium fiber lasers. A key challenge in such systems-the limited lifetime of the Tm3+ 3H4 energy level (300 − 500 µs)–has traditionally restricted pulse frequency and stability. By applying nonlinear dynamical systems theory, we provide a rigorous Floquet-based analysis that certifies the stability of periodic pulse solutions under perturbations. The theoretical model is complemented by experimental results demonstrating that spectral complementarity between Tm and Er ions eliminates gain competition, thereby enhancing pulse consistency. This combined approach offers new design principles for rare-earth-doped fiber systems, with direct implications for high-performance applications in biomedical laser processing and free-space optical communication.

Relating problems in two dimensions. A particle in a uniform magnetic field and a free particle

Gerardo Francisco Torres del Castillo — 2026-01-01

We give a coordinate transformation in the extended configuration space that maps the trajectories of a free particle in two dimensions into the trajectories of a charged particle in a uniform magnetic field. We show that this coordinate transformation also relates the solutions of the Schrödinger equations for these two problems.

Coherent states of a free particle from the coherent states of the harmonic oscillator

Jasel Berra Montiel — 2026-01-01

We construct the coherent states of a free particle by implementing a coordinate transformation in the extended configuration space, which establishes a correspondence between the solutions of the Schrödinger equation for a harmonic oscillator and those for a free particle. Using this framework, we derive analytical expressions for the coherent states of a free particle, avoiding the complexities of non-normalizable fiducial states, integrals of motion, or group-theoretic approaches. Our method provides a systematic way to characterize these states at any instant while ensuring that they satisfy the Robertson-Schrödinger uncertainty relation.

Hybrid Optimization for High-Precision Parameter Extraction in Mo/Au/AlGaN/GaN Schottky Diodes

Mohammed Mostefaoui — 2026-01-01

Accurate parameter extraction is essential for understanding and optimizing the performance of Mo/AlGaN/GaN Schottky barrier diodes (SBDs). Traditional methods often introduce approximation errors, particularly in the presence of high series resistance. In this study, we propose a hybrid approach that combines Nonlinear Least Squares Fitting (NLSF) with the Lambert W function and Grey Wolf Optimization (GWO) to achieve high-precision extraction of key diode parameters, including the ideality factor (n), barrier height (Φb), and series resistance (Rs). By leveraging the strengths of both analytical and metaheuristic techniques, this method enhances accuracy and robustness in parameter estimation. Experimental validation across a wide temperature range (100 K – 450 K) demonstrates the effectiveness of the proposed approach, highlighting its advantages over conventional extraction techniques.

Performance enhancement of SnSb₂Se₃S solar cells through structural and optoelectronic modifications

U.K. Anjali — 2026-01-01

This study investigates the optoelectronic properties of SnSb₂Se₃S, a novel material, for the first time, and evaluates its potential as a high-absorption thin-film solar cell absorber. Leveraging its unique nanoscale attributes and potential for Multiple Exciton Generation (MEG), SnSb₂Se₃S is explored for its capacity to enhance light absorption and charge carrier transport, positioning it as a promising candidate for advanced photovoltaic applications. A detailed analysis of Power Conversion Efficiency (PCE) as a function of absorber layer thickness demonstrates a direct correlation, with PCE values increasing from 5.87% at 2500 nm to 5.96% at 3000 nm. The impact of electron affinity on PCE is also examined, revealing an inverse relationship wherein increased electron affinity results in decreased efficiency due to alterations in charge transport dynamics. Furthermore, the temperature dependence of PCE is analyzed, indicating robust stability across a range of operating temperatures. Quantum Efficiency (QE) measurements show a significant response at 1240 nm, confirming effective infrared absorption. The carrier generation rate is evaluated, confirming efficient photon-to-electron conversion within the absorber layer. These results provide critical insights into the viability of SnSb₂Se₃S as an alternative absorber material for next-generation solar cells, setting the stage for subsequent experimental validation and device optimization.