Viabilidade de implantacao de aveia em pastagens estabelecidas de capim-elefante.

bitstream/item/142996/1/2033.pd

Entanglement negativity in a two dimensional harmonic lattice: Area law and corner contributions

We study the logarithmic negativity and the moments of the partial transpose in the ground state of a two dimensional massless harmonic square lattice with nearest neighbour interactions for various configurations of adjacent domains. At leading order for large domains, the logarithmic negativity and the logarithm of the ratio between the generic moment of the partial transpose and the moment of the reduced density matrix at the same order satisfy an area law in terms of the length of the curve shared by the adjacent regions. We give numerical evidence that the coefficient of the area law term in these quantities is related to the coefficient of the area law term in the R\ue9nyi entropies. Whenever the curve shared by the adjacent domains contains vertices, a subleading logarithmic term occurs in these quantities and the numerical values of the corner function for some pairs of angles are obtained. In the special case of vertices corresponding to explementary angles, we provide numerical evidence that the corner function of the logarithmic negativity is given by the corner function of the R\ue9nyi entropy of order 1/2

A contour for the entanglement entropies in harmonic lattices

We construct a contour function for the entanglement entropies in generic harmonic lattices. In one spatial dimension, numerical analysis are performed by considering harmonic chains with either periodic or Dirichlet boundary conditions. In the massless regime and for some configurations where the subsystem is a single interval, the numerical results for the contour function are compared to the inverse of the local weight function which multiplies the energy-momentum tensor in the corresponding entanglement hamiltonian, found through conformal field theory methods, and a good agreement is observed. A numerical analysis of the contour function for the entanglement entropy is performed also in a massless harmonic chain for a subsystem made by two disjoint intervals

Universal scaling of the logarithmic negativity in massive quantum field theory

We consider the logarithmic negativity, a measure of bipartite entanglement, in a general unitary 1 + 1-dimensional massive quantum field theory, not necessarily integrable. We compute the negativity between a finite region of length r and an adjacent semi-infinite region, and that between two semi-infinite regions separated by a distance r. We show that the former saturates to a finite value, and that the latter tends to zero, as r -> ∞. We show that in both cases, the leading corrections are exponential decays in r (described by modified Bessel functions) that are solely controlled by the mass spectrum of the model, independently of its scattering matrix. This implies that, like the entanglement entropy (EE), the logarithmic negativity displays a very high level of universality, allowing one to extract information about the mass spectrum. Further, a study of sub-leading terms shows that, unlike the EE, a large-r analysis of the negativity allows for the detection of bound states

Spin structures and entanglement of two disjoint intervals in conformal field theories

We reconsider the moments of the reduced density matrix of two disjoint intervals and of its partial transpose with respect to one interval for critical free fermionic lattice models. It is known that these matrices are sums of either two or four Gaussian matrices and hence their moments can be reconstructed as computable sums of products of Gaussian operators. We find that, in the scaling limit, each term in these sums is in one-to-one correspondence with the partition function of the corresponding conformal field theory on the underlying Riemann surface with a given spin structure. The analytical findings have been checked against numerical results for the Ising chain and for the XX spin chain at the critical point

Towards the entanglement negativity of two disjoint intervals for a one dimensional free fermion

We study the moments of the partial transpose of the reduced density matrix of two intervals for the free massless Dirac fermion. By means of a direct calculation based on a coherent state path integral, we find an analytic form for these moments in terms of the Riemann theta function. We show that moments of arbitrary order are equal to the same quantities for the compactified boson at the self-dual point. These equalities also imply the nontrivial result that the negativity of the free fermion and the self-dual boson are equal

Entanglement Hamiltonians in 1D free lattice models after a global quantum quench

We study the temporal evolution of the entanglement Hamiltonian of an interval after a global quantum quench in free lattice models in one spatial dimension. In a harmonic chain we explore a quench of the frequency parameter. In a chain of free fermions at half filling we consider the evolution of the ground state of a fully dimerised chain through the homogeneous Hamiltonian. We focus on critical evolution Hamiltonians. The temporal evolutions of the gaps in the entanglement spectrum are analysed. The entanglement Hamiltonians in these models are characterised by matrices that provide also contours for the entanglement entropies. The temporal evolution of these contours for the entanglement entropy is studied, also by employing existing conformal field theory results for the semi-infinite line and the quasi-particle picture for the global quench

Blurred Boundaries: Gender and Work-Family Interference in Cross-National Context

Although well theorized at the individual level, previous research has neglected the role of national context in shaping overall levels of nonwork-work and work-nonwork interference. This study fills this gap by examining how a national context of gender empowerment affects the likelihood of experiencing nonwork-work and work-nonwork interference at the individual and national levels. Controlling for individual-level differences in the distribution of job demands and resources, results from our multilevel models indicate that women's empowerment has significant net gender and parenthood effects on nonwork-work interference. By contrast, gender empowerment equally structures work-nonwork interference for these groups. Our results highlight the need to investigate interference bidirectionally and in a multilevel context. © The Author(s) 2013

Liberação de nutrientes durante a decomposição de resíduos vegetais de macaúba em áreas com variações de lençol freático.

O objetivo deste trabalho foi determinar a liberação de macronutrientes durante o processo de decomposição de resíduos vegetais de macaúba (Acrocomia aculeata (Jacq.) Lodd. ex Mart.) em duas áreas sob condições de lençol freático alto e baixo. Para determinar a decomposição e liberação de nutrientes foram coletadas folhas secas de uma população natural de macaúba. O material vegetal foi colocado em litter bags e avaliado por um período de 420 dias (de dezembro de 2010 a janeiro de 2012). A taxa de decomposição do material vegetal de macaúba foi maior até os 180 dias após a colocação dos litter bags no campo, variando entre 49 e 59%. A liberação de K foi mais rápida sob condição de lençol freático alto. A liberação de nutrientes dos resíduos vegetais de macaúba acompanha o comportamento da dinâmica de decomposição, mostrando-se maior no início do processo de decomposição e estabilizada na época da seca

Caregiving stress among American Indians with Type 2 diabetes: The importance of awareness of connectedness and family support

American Indian (AI) communities experience a disproportionate rate of Type 2 diabetes (T2D) and cumulative exposure to stress. Although this link is well researched among various populations, it has not been examined among AI communities. Path analysis was used to examine a multiple-mediator model to explain how caregiver stress influences self-reported mental and physical health among 100 AI participants with T2D. Caregiver stress was negatively associated with physical and mental health. Physical health was positively associated with family/community connectedness and mental health was positively associated with both family support and connectedness. The relationship between caregiver stress and mental health was partially mediated by family/community connectedness; caregiver stress had no indirect effects on physical health via either hypothesized mediator. Findings demonstrate the importance of integrating individuals’ connection to family and community and its influence on caregiver stress and mental health in intervention programs targeting diabetes management and care among AI communities.Peer reviewedPsychologySociolog