RESUMO

We study two coupled 3D lattices, one of them featuring uncorrelated on-site disorder and the other one being fully ordered, and analyze how the interlattice hopping affects the localization-delocalization transition of the former and how the latter responds to it. We find that moderate hopping pushes down the critical disorder strength for the disordered channel throughout the entire spectrum compared to the usual phase diagram for the 3D Anderson model. In that case, the ordered channel begins to feature an effective disorder also leading to the emergence of mobility edges but with higher associated critical disorder values. Both channels become pretty much alike as their hopping strength is further increased, as expected. We also consider the case of two disordered components and show that in the presence of certain correlations among the parameters of both lattices, one obtains a disorder-free channel decoupled from the rest of the system.

RESUMO

This work investigates the dynamical properties of classical and quantum random walks on mean-field small-world (MFSW) networks in the continuous time version. The adopted formalism profits from the large number of exact mathematical properties of their adjacency and Laplacian matrices. Exact expressions for both transition probabilities in terms of Bessel functions are derived. Results are compared to numerical results obtained by working directly the Hamiltonian of the model. For the classical evolution, any infinitesimal amount of disorder causes an exponential decay to the asymptotic equilibrium state, in contrast to the polynomial behavior for the homogeneous case. The typical quantum oscillatory evolution has been characterized by local maxima. It indicates polynomial decay to equilibrium for any degree of disorder. The main finding of the work is the identification of a faster classical spreading as compared to the quantum counterpart. It stays in opposition to the well known diffusive and ballistic for, respectively, the classical and quantum spreading in the linear chain.

RESUMO

Precision agriculture requires faster and automatic responses for fertility parameters, especially regarding soil organic matter (SOM). In Brazil, the standard methodology for SOM determination is a wet procedure based on the oxidation of the sample by an excess of potassium dichromate based on Walkley-Black method. This methodology has serious drawbacks, since, at a national level, generates approximately 600,000 L/year of toxic acid waste containing Cr3+ and possibly Cr6+, besides time consuming and expensive. Herein, we present a faster green methodology that can eliminate the generation of these hazardous wastes and reduces the costs of analysis by approximately 80%, democratizing the soil fertility information and increasing the productivity. The methodology is based on the use of a national near infrared spectral library with approximately 43,000 samples and learning machine data analysis based on a random forest algorithm. The methodology was validated by submitting the prediction results of 12 blind soil samples to a proficiency assay used for fertility soil laboratories qualification, receiving the maximum quality excellence index, indicating that it is suitable for use in routine analysis.

RESUMO

The ground state of a two-level system (associated with probabilities p and 1-p, respectively) defined by a general Hamiltonian H[over ̂]=H[over ̂]_{0}+λV[over ̂] is studied. The simple case characterized by λ=0, whose Hamiltonian H[over ̂]_{0} is represented by a diagonal matrix, is well established and solvable within Boltzmann-Gibbs statistical mechanics; in particular, it follows the third law of thermodynamics, presenting zero entropy (S_{BG}=0) at zero temperature (T=0). Herein it is shown that the introduction of a perturbation λV[over ̂] (λ>0) in the Hamiltonian may lead to a nontrivial ground state, characterized by an entropy S[p] (with S[p]≠S_{BG}[p]), if the Hermitian operator V[over ̂] is represented by a 2×2 matrix, defined by nonzero off-diagonal elements V_{12}=V_{21}=-z, where z is a real positive number. Hence, this new term in the Hamiltonian, presenting V_{12}≠0, may produce physically significant changes in the ground state, and especially, it allows for the introduction of an effective temperature θ (θ∝λz), which is shown to be a parameter conjugated to the entropy S. Based on this, one introduces an infinitesimal heatlike quantity, δQ=θdS, leading to a consistent thermodynamic framework, and by proposing an infinitesimal form for the first law, a Carnot cycle and thermodynamic potentials are obtained. All results found are very similar to those of usual thermodynamics, through the identification T↔θ, and particularly the form for the efficiency of the proposed Carnot Cycle. Moreover, S also follows a behavior typical of a third law, i.e., S→0, when θ→0.

RESUMO

An effective temperature θ, conjugated to a generalized entropy s(q), was introduced recently for a system of interacting particles. Since θ presents values much higher than those of typical room temperatures T≪θ, the thermal noise can be neglected (T/θ≃0) in these systems. Moreover, the consistency of this definition, as well as of a form analogous to the first law of thermodynamics, du=θds(q)+δW, were verified lately by means of a Carnot cycle, whose efficiency was shown to present the usual form, η=1-(θ(2)/θ(1)). Herein we explore further the heat contribution δQ=θds(q) by proposing a way for a heat exchange between two such systems, as well as its associated thermal equilibrium. As a consequence, the zeroth principle is also established. Moreover, we consolidate the first-law proposal by following the usual procedure for obtaining different potentials, i.e., applying Legendre transformations for distinct pairs of independent variables. From these potentials we derive the equation of state, Maxwell relations, and define response functions. All results presented are shown to be consistent with those of standard thermodynamics for T>0.

RESUMO

A thermodynamic formalism is developed for a system of interacting particles under overdamped motion, which has been recently analyzed within the framework of nonextensive statistical mechanics. It amounts to expressing the interaction energy of the system in terms of a temperature θ, conjugated to a generalized entropy s(q), with q = 2. Since θ assumes much higher values than those of typical room temperatures T ≪ θ, the thermal noise can be neglected for this system (T/θ ≃ 0). This framework is now extended by the introduction of a work term δW which, together with the formerly defined heat contribution (δ Q = θ ds(q)), allows for the statement of a proper energy conservation law that is analogous to the first law of thermodynamics. These definitions lead to the derivation of an equation of state and to the characterization of s(q) adiabatic and θ isothermic transformations. On this basis, a Carnot cycle is constructed, whose efficiency is shown to be η = 1-(θ(2)/θ(1)), where θ(1) and θ(2) are the effective temperatures of the two isothermic transformations, with θ(1)>θ(2). The results for a generalized thermodynamic description of this system open the possibility for further physical consequences, like the realization of a thermal engine based on energy exchanges gauged by the temperature θ.

RESUMO

O deslocamento do abomaso caracteriza-se pela patologia mais frequente do trato gastro intestinal dos ruminantes, representa a principal causa de cirurgia abdominal em vacas de leite de alta produção, comumente diagnosticada no período pós-parto inicial.  Os fatores predisponentes são atribuídos às falhas no manejo nutricional na fase de transição, onde ocorre o fornecimento de dieta rica em energia, altamente fermentável e deficiente em fibras. Desta forma, os movimentos abomasais serão reduzidos, permitindo o acúmulo de gás no local, tendo como consequência, a distensão e o deslocamento do órgão. Descreve-se como principal sinal clínico a redução acentuada no volume de leite produzido. O diagnóstico é firmado através da anamnese somada ao exame clínico detalhado, que permite a auscultação de som metálico-timpânico no abomaso denominado ping. A intervenção cirúrgica faz-se necessária na maioria dos casos. Assim, o presente artigo objetiva descrever um caso de deslocamento de abomaso à esquerda em vaca de leite de alta produção na segunda semana pós-parto com sucesso terapêutico. Optou-se pelo tratamento cirúrgico aberto, mediante laparotomia pelo flanco esquerdo e abomasopexia. O procedimento clínico escolhido é uma técnica de fácil execução, rápido retorno à ordenha e baixo custo operacional, o que viabiliza a utilização deste em situações de campo.

Abomasal displacement is the most frequent disease of the gastrointestinal intestinal tract of ruminants. It is the leading cause of abdominal surgery in high producing dairy cows, and is commonly diagnosed in the early postnatal period. Predisposing factors are flaws in nutritional management during the transition phase, when a highly fermentable, energy-rich, and fiber-deficient diet is offered to the animals. Thus, abomasal movements are reduced, enabling gas accumulation, and resulting in distention and dislocation of this organ. The main clinical sign is a sharp reduction in the volume of milk produced. Diagnosis is confirmed by history, coupled with detailed clinical examination showing a metallic sound in abomasum, called "ping". Surgical intervention is necessary in most cases. The present study aims to describe a successful treatment for left abomasal displacement in cattle. Open surgical treatment by laparotomy on the left flank and abomasopexy were used. The clinical procedure chosen in this case is a simple technique, determining fast return to normal milking, and has low cost, enabling its use in field situations.

Assuntos

RESUMO

O deslocamento do abomaso caracteriza-se pela patologia mais frequente do trato gastro intestinal dos ruminantes, representa a principal causa de cirurgia abdominal em vacas de leite de alta produção, comumente diagnosticada no período pós-parto inicial.  Os fatores predisponentes são atribuídos às falhas no manejo nutricional na fase de transição, onde ocorre o fornecimento de dieta rica em energia, altamente fermentável e deficiente em fibras. Desta forma, os movimentos abomasais serão reduzidos, permitindo o acúmulo de gás no local, tendo como consequência, a distensão e o deslocamento do órgão. Descreve-se como principal sinal clínico a redução acentuada no volume de leite produzido. O diagnóstico é firmado através da anamnese somada ao exame clínico detalhado, que permite a auscultação de som metálico-timpânico no abomaso denominado ping. A intervenção cirúrgica faz-se necessária na maioria dos casos. Assim, o presente artigo objetiva descrever um caso de deslocamento de abomaso à esquerda em vaca de leite de alta produção na segunda semana pós-parto com sucesso terapêutico. Optou-se pelo tratamento cirúrgico aberto, mediante laparotomia pelo flanco esquerdo e abomasopexia. O procedimento clínico escolhido é uma técnica de fácil execução, rápido retorno à ordenha e baixo custo operacional, o que viabiliza a utilização deste em situações de campo.(AU)

Abomasal displacement is the most frequent disease of the gastrointestinal intestinal tract of ruminants. It is the leading cause of abdominal surgery in high producing dairy cows, and is commonly diagnosed in the early postnatal period. Predisposing factors are flaws in nutritional management during the transition phase, when a highly fermentable, energy-rich, and fiber-deficient diet is offered to the animals. Thus, abomasal movements are reduced, enabling gas accumulation, and resulting in distention and dislocation of this organ. The main clinical sign is a sharp reduction in the volume of milk produced. Diagnosis is confirmed by history, coupled with detailed clinical examination showing a metallic sound in abomasum, called "ping". Surgical intervention is necessary in most cases. The present study aims to describe a successful treatment for left abomasal displacement in cattle. Open surgical treatment by laparotomy on the left flank and abomasopexy were used. The clinical procedure chosen in this case is a simple technique, determining fast return to normal milking, and has low cost, enabling its use in field situations. (AU)

Assuntos

RESUMO

The H-theorem [(df/dt) ≤ 0] for a free-energy functional, f = u-θs (with u and s representing, respectively, the internal energy and a generalized entropy of a given physical system), has been proven previously by making use of a nonlinear Fokker-Planck equation. Herein we focus on a nonlinear Fokker-Planck equation derived by means of a coarse-graining procedure on the equations of motion of a system of interacting vortices, under overdamped motion, in the absence of thermal noise (T = 0). In this case, we show that the parameter θ is directly related to the density as well as to the interactions among vortices. Generalized quantities such as entropy, internal energy, free energy, and heat capacity are analyzed for varying θ: important relations and physical behavior analogous to those of standard thermodynamics are found, showing that θ plays the role of an effective temperature. Estimates of θ in typical physical situations of different type-II superconductors are presented; in addition to this, possible experimental procedures for varying θ are proposed.

RESUMO

Pharmaceutical pellets are spherical or nearly spherical multi-unit dosage forms designed to optimize pharmacokinetics and pharmacodynamics features of drug release. The distribution of the pharmaceutical ingredients in the layers and core is a very important parameter for appropriate drug release, especially for pellets manufactured by the process of layer gain. Physical aspects of the sample are normally evaluated by Scanning Electron Microscopy (SEM), but it is in many cases unsuitable to provide conclusive chemical information about the distribution of the pharmaceutical ingredients in both layers and core. On the other hand, methods based on spectroscopic imaging can be very promising for this purpose. In this work, a Near-Infrared Chemical Imaging (NIR-CI) method was developed and applied to the analysis of diclophenac sodium pellets. Since all the compounds present in the sample were known in advance, Classical Least Squares (CLS) was used for calculations. The results have shown that the method was capable of providing chemical information about the distribution of the active ingredient and excipients in the core and coating layers and therefore can be complementary to SEM for the pharmaceutical development of pellets.

Assuntos

RESUMO

We study wave transport through a chaotic quantum billiard attached to two waveguides via barriers of arbitrary transparencies in the semiclassical limit of a large number of open scattering channels. We focus attention on the ergodic regime, which is described by using a random-matrix approach to chaotic resonance scattering together with an extended version of Nazarov's circuit theory. By varying the relative strength of the barriers' transparencies a reorganization of the relevant resonances in the energy interval where transport takes place leads to a full suppression of high transmission modes. We provide a detailed quantitative description of the process by means of both numerical and analytical evaluations of the average density of transmission eigenvalues. We show that the density of Fabry-Perot modes can be used as a kind of order parameter for this quantum transition. A diagram is presented as a function of the transparencies of the barriers exhibiting the transport regimes and the transition lines.

RESUMO

The basic aspects of both Boltzmann-Gibbs (BG) and nonextensive statistical mechanics can be seen through three different stages. First, the proposal of an entropic functional (S(BG)=-k Sigma(i)p(i)ln p(i) for the BG formalism) with the appropriate constraints (Sigma(i)p(i)=1 and Sigma(i)p(i)E(i)=U for the BG canonical ensemble). Second, through optimization, the equilibrium or stationary-state distribution (p(i)=e(-betaE(i))/Z(BG) with Z(BG)= Sigma(j)e(-betaE(j)) for BG). Third, the connection to thermodynamics (e.g., F(BG)=-(1/beta)ln Z(BG) and U(BG)=-(partial differential/partial differential beta)ln Z(BG)). Assuming temperature fluctuations, Beck and Cohen recently proposed a generalized Boltzmann factor B(E)= integral (infinity)(0)dbetaf(beta)e(-betaE). This corresponds to the second stage described above. In this paper, we solve the corresponding first stage, i.e., we present an entropic functional and its associated constraints which lead precisely to B(E). We illustrate with all six admissible examples given by Beck and Cohen.