Effects of nanoscale spatial inhomogeneity in strongly correlated systems

We calculate ground-state energies and density distributions of Hubbard superlattices characterized by periodic modulations of the on-site interaction and the on-site potential. Both density-matrix renormalization group and density-functional methods are employed and compared. We find that small variations in the on-site potential $v_i$ can simulate, cancel, or even overcompensate effects due to much larger variations in the on-site interaction $U_i$. Our findings highlight the importance of nanoscale spatial inhomogeneity in strongly correlated systems, and call for reexamination of model calculations assuming spatial homogeneity.Comment: 5 pages, 1 table, 4 figures, to appear in PR

Predicting Psi-BN: computational insights into its mechanical, electronic, and optical characteristics

Computational materials are pivotal in advancing our understanding of distinct material classes and their properties, offering valuable insights in predicting novel structures and complementing experimental approaches. In this context, Psi-graphene is a stable two-dimensional carbon allotrope composed of 5-6-7 carbon rings theoretically predicted recently. Using density functional theory (DFT) calculations, we explored its boron nitride counterpart's mechanical, electronic, and optical characteristics (Psi-BN). Our results indicate that Psi-BN possesses a band gap of 4.59 eV at the HSE06 level. Phonon calculations and ab initio molecular dynamics simulations demonstrated that this material has excellent structural and dynamic stability. Moreover, its formation energy is -7.48 eV. Psi-BN exhibited strong ultraviolet activity, suggesting its potential as an efficient UV collector. Furthermore, we determined critical mechanical properties of Psi-BN, such as the elastic stiffness constants, Young's modulus (250-300 GPa), and Poisson ratio (0.7), providing valuable insights into its mechanical behavior.Comment: 13 pages, 7 figure

Probing the two-scale-factor universality hypothesis by exact rotation symmetry-breaking mechanism

We probe the two-scale factor universality hypothesis by evaluating, firstly explicitly and analytically at the one-loop order, the loop quantum corrections to the amplitude ratios for O($N$) $\lambda\phi^{4}$ scalar field theories with rotation symmetry-breaking in three distinct and independent methods in which the rotation symmetry-breaking mechanism is treated exactly. We show that the rotation symmetry-breaking amplitude ratios turn out to be identical in the three methods and equal to their respective rotation symmetry-breaking ones, although the amplitudes themselves, in general, depend on the method employed and on the rotation symmetry-breaking parameter. At the end, we show that all these results can be generalized, through an inductive process based on a general theorem emerging from the exact calculation, to any loop level and physically interpreted based on symmetry ideas.Comment: 17 pages, 3 figure

Majority-Vote Model on a Random Lattice

The stationary critical properties of the isotropic majority vote model on random lattices with quenched connectivity disorder are calculated by using Monte Carlo simulations and finite size analysis. The critical exponents $\gamma$ and $\beta$ are found to be different from those of the Ising and majority vote on the square lattice model and the critical noise parameter is found to be $q_{c}=0.117\pm0.005$.Comment: 4 pages, 6 figure

Density-functionals not based on the electron gas: Local-density approximation for a Luttinger liquid

By shifting the reference system for the local-density approximation (LDA) from the electron gas to other model systems one obtains a new class of density functionals, which by design account for the correlations present in the chosen reference system. This strategy is illustrated by constructing an explicit LDA for the one-dimensional Hubbard model. While the traditional {\it ab initio} LDA is based on a Fermi liquid (the electron gas), this one is based on a Luttinger liquid. First applications to inhomogeneous Hubbard models, including one containing a localized impurity, are reported.Comment: 4 pages, 4 figures (final version, contains additional applications and discussion; accepted by Phys. Rev. Lett.

Magnetic phases evolution in the LaMn1-xFexO3+y system

We have investigated the crystal structure and magnetic properties for polycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0, prepared by solid state reaction in air. All samples show the ORT-2 orthorhombic structure that suppresses the Jahn-Teller distortion, thus favoring a ferromagnetic (FM) superexchange (SE) interaction between Mn^{3+}-O-Mn^{3+}. For x=0.0 the oxygen excess (y ~ 0.09) produces vacancies in the La and Mn sites and generates a fraction around 18% of Mn^{4+} ions and 82% of the usual Mn^{3+} ions, with possible double exchange interaction between them. The Fe doping in this system is known to produce only stable Fe^{3+} ions. We find an evolution from a fairly strong FM phase with a Curie temperature T_{C} ~ 160 K, for x=0.0, to an antiferromagnetic (AFM) phase with T_{N} = 790 K, for x=1.0, accompanied by clear signatures of a cluster-glass behavior. For intermediate Fe contents a mixed-phase state occurs, with a gradual decrease (increase) of the FM (AFM) phase, accompanied by a systematic transition broadening for 0.2 < x < 0.7. A model based on the expected exchange interaction among the various magnetic-ion types, accounts very well for the saturation-magnetization dependence on Fe doping.Comment: 27 pages, 9 figure

Boas práticas de fabricação como estratégia para impedir a contaminação de peixes frescos eviscerados por Salmonella.

As salmonelas são micro-organismos amplamente distribuídos na natureza e possuem como principal reservatório o trato intestinal homem e de aves. No caso de peixes, moluscos e crustáceos, a sua presença está relacionada, principalmente, com o manejo pós-despesca, o qual pode representar um risco sanitário e econômico para os entrepostos de processamento. A partir deste problema, objetivou-se nesse trabalho investigar possíveis causas para a contaminação de peixes eviscerados frescos por spp. em uma agroindústria de pescado.Organizado por: Sílvio Ricardo Maurano; AQUACIÊNCIA 2012

Changing the production chain of Amazonian pirarucu.

This article summarizes these recent findings and envisions how these are impacting the production sector in the short and medium terms. Recent studies in Brazil have addressed the main challenges faced by commercial producers of pirarucu, including breeding, larval rearing, grow-out, feeding, health management, processing and more

Influencia da nutrição sobre a qualidade do pescado: especial referência aos ácidos graxos.

Reconhecida como uma fonte de proteína de alta qualidade, a carne de pescado tem sido objeto de inúmeras pesquisas relacionadas à sua composição em ácidos graxos, dentre os quais se encontram os popularmente conhecidos como ômega-3, os quais estão diretamente associados à saúde humana pelo seu efeito protetor, principalmente contra doenças cardiovasculares e reumatismo. Nesse sentido, um dos grandes desafios da aquicultura é apresentar ao consumidor um produto final que se assemelhe, em termos nutricionais e sensoriais, aos peixes capturados na natureza que são ricos em ácidos graxos. Este documento faz uma revisão da influência da nutrição nos peixes cultivados sobre a composição de ácidos graxos e a importância dessa como ferramenta para melhorar a qualidade nutricional e agregar valor ao pescado.bitstream/item/101804/1/DOC124.pd

High emotional contagion and empathy are associated with enhanced detection of emotional authenticity in laughter

Nonverbal vocalisations such as laughter pervade social interactions, and the ability to accurately interpret them is an important skill. Previous research has probed the general mechanisms supporting vocal emotional processing, but the factors that determine individual differences in this ability remain poorly understood. Here, we ask whether the propensity to resonate with others’ emotions—as measured by trait levels of emotional contagion and empathy—relates to the ability to perceive different types of laughter. We focus on emotional authenticity detection in spontaneous and voluntary laughs: spontaneous laughs reflect a less controlled and genuinely felt emotion, and voluntary laughs reflect a more deliberate communicative act (e.g., polite agreement). In total, 119 participants evaluated the authenticity and contagiousness of spontaneous and voluntary laughs and completed two self-report measures of resonance with others’ emotions: the Emotional Contagion Scale and the Empathic Concern scale of the Interpersonal Reactivity Index. We found that higher scores on these measures predict enhanced ability to detect laughter authenticity. We further observed that perceived contagion responses during listening to laughter significantly relate to authenticity detection. These findings suggest that resonating with others’ emotions provides a mechanism for processing complex aspects of vocal emotional information.info:eu-repo/semantics/acceptedVersio