We investigate how exchange interactions shape both quantum entanglement and the magnon Nernst effect in a two-dimensional ferromagnet on a honeycomb lattice. In particular, we examine how variations in the exchange parameters influence the spin Nernst coefficient and, in turn, modify the entanglement properties of the system. Entanglement negativity is employed as the primary quantifier of quantum correlations, providing a reliable measure for mixed states. Our analysis of the spin Nernst response shows that the coefficient vanishes at zero temperature, reflecting the absence of thermally excited magnons in this limit.
Understanding the recovery of phylogenetic diversity during tropical forest succession is critical for informing ecosystem stability, conserving evolutionary history, and guiding restoration. To address these goals, we evaluated patterns of phylogenetic diversity, structure, and lineage turnover across 61 s-growth and 18 old-growth forest communities in three regions of the Brazilian Atlantic Forest. We asked whether second-growth forests recover the phylogenetic diversity found in old-growth forests over time, whether there is a consistent pattern of community assembly along succession, whether functional traits are phylogenetically conserved, and to what extent second-growth forests contribute to evolutionary history conservation at the landscape scale. Our results revealed that second-growth forests exhibit increasing species richness and phylogenetic diversity with forest age. However, standardized phylogenetic structure metrics (sesPD, sesMPD, sesMNTD) remained stable along succession and did not differ from old-growth forests, suggesting that successional time alone does not shape phylogenetic structure. Most functional traits showed low phylogenetic signal, indicating a decoupling between phylogenetic and functional recovery. Despite the absence of some rare and evolutionarily distinct lineages, particularly within Malpighiales, in second-growth forests, beta diversity analyses demonstrated that combining both forest types conserves a broader set of lineages than either type alone. This phylogenetic complementarity underscores the value of conserving both forest types as complementary components of regional biodiversity. Our findings emphasize the role of second-growth forests in preserving evolutionary history and support their inclusion in conservation and restoration strategies. By integrating broad-scale phylogenetic analyses with regional datasets, this study enhances our understanding of biodiversity recovery in one of the world's most threatened tropical biomes.
Polycyclic aromatic hydrocarbons (PAHs) are priority environmental contaminants frequently detected at trace levels in aquatic systems, necessitating sensitive and reliable analytical methodologies for their determination. In this study, a comparative analytical evaluation of intra-tube flow extraction (IT-FEx) and solid-phase microextraction (SPME) was conducted for the determination of PAHs in water samples. Both extraction techniques were optimized and coupled to comprehensive two-dimensional gas chromatography, and their analytical performance was assessed for linearity, sensitivity, precision, accuracy, and applicability to real samples. The methods showed good linearity for all target compounds. For the IT-FEx-based method, limits of detection ranged from 0.005 to 8.107 mu g L- 1, while limits of quantification ranged from 0.024 to 9.197 mu g L- 1, depending on the compound. The methods showed good linearity for all target compounds, with coefficients of determination (R2) ranging from 0.90 to 0.99. Precision, expressed as intra- and inter-day relative standard deviation, ranged from 6.6% to 14.8%, and recoveries from spiked water samples were within the acceptable range of 80-120%, demonstrating satisfactory accuracy. Application of both methods to real water samples revealed clear differences in extraction performance. IT-FEx enabled the detection of a broader range of PAHs and yielded higher Sigma PAH concentrations, allowing simultaneous extraction of compounds of different molecular weights. In contrast, SPME exhibited more selective extraction, with several PAHs detected at concentrations near the quantification limits. Overall, the results show that IT-FEx provides improved analytical coverage and comparable or higher sensitivity for most analytes, which can be attributed to its flow-assisted extraction mechanism that enhances mass transfer and minimizes diffusional limitations. These characteristics make IT-FEx a robust, efficient, and environmentally sustainable alternative for the determination of PAHs in water matrices.
We investigate quantum correlations and entanglement in a non-Hermitian quantum system modeled by a 2D stacked Su-Schrieffer-Heeger (SSH) lattice incorporating nonreciprocal hopping amplitudes and balanced on-site gain and loss. Focusing on the interplay between non-Hermiticity, topology, and open-boundary conditions, we analyze how these factors shape bipartite entanglement properties, characterized through the entanglement spectrum and entanglement negativity (EN). By examining the complex energy spectrum under open boundary conditions, we identify critical points associated with the closing of complex energy gaps, which significantly influence entanglement structure and signal topological phase transitions. Our findings reveal that boundary-localized non-Bloch modes and nonreciprocal couplings can induce highly tunable and unconventional entanglement features, absent under periodic boundary conditions. These results highlight the breakdown of conventional bulk-boundary correspondence and underscore the utility of entanglement measures in diagnosing non-Hermitian topological phases. Beyond advancing the fundamental understanding of quantum correlations in open systems, our study suggests potential pathways to engineer quantum devices and topological materials where gain, loss, and nonreciprocity are intrinsic elements.
This work introduces the Single Source Capacitated Partial Set Covering Location Problem (SSCPSCLP). Given a set of potential capacitated facilities and a set of customers with their demands, this problem consists of determining the facilities to be opened and the customers to be served to minimize the total cost of opening facilities, ensuring that at least a minimum amount of the total demand is served, only covered customers can be served, the capacity of the facilities is not exceeded, and each customer can be served by at most one facility. This work introduces a mathematical model for the problem and, since it is NP-hard, develops an algorithm based on the Tabu Search (TS) metaheuristic to handle large-scale instances. The TS algorithm explores the problem’s solution space through two neighborhoods, one of which is incorporated into a local search procedure that is periodically applied. The initial solution is generated either by a constructive greedy heuristic or by solving the linear relaxation of the SSCPSCLP. Four TS variants were proposed, differing in the method for generating the initial solution and in the use of local search. The results of computational experiments on instances from the literature show that the TS algorithm finds high-quality solutions in a shorter runtime than a mathematical programming-based solver and that the version using initial solutions from the linear relaxation of the problem and local search performs best.
