Tailored graph ensembles as proxies or null models for real networks I: tools for quantifying structure

We study the tailoring of structured random graph ensembles to real networks, with the objective of generating precise and practical mathematical tools for quantifying and comparing network topologies macroscopically, beyond the level of degree statistics. Our family of ensembles can produce graphs with any prescribed degree distribution and any degree-degree correlation function, its control parameters can be calculated fully analytically, and as a result we can calculate (asymptotically) formulae for entropies and complexities, and for information-theoretic distances between networks, expressed directly and explicitly in terms of their measured degree distribution and degree correlations.Comment: 25 pages, 3 figure

Variabilidade temporal da produtividade da soja após conversão do preparo convencional para o sistema plantio direto.

bitstream/item/71979/1/ID-30951.pd

Qualidade física do solo em um sistema de integração lavoura-pécuaria com diferentes pressões de pastejo.

bitstream/item/71522/1/ID-30987.pd

On the heating of source of the Orion KL hot core

We present images of the J=10-9 rotational lines of HC3N in the vibrationally excited levels 1v7, 1v6 and 1v5 of the hot core (HC) in Orion KL. The images show that the spatial distribution and the size emission from the 1v7 and 1v5 levels are different. While the J=10-9 1v7 line has a size of 4''x 6'' and peaks 1.1'' NE of the 3 mm continuum peak, the J=10--9 1v5 line emission is unresolved (<3'') and peaks 1.3'' south of the 3 mm peak. This is a clear indication that the HC is composed of condensations with very different temperatures (170 K for the 1v7 peak and $>230$ K for the 1v5 peak). The temperature derived from the 1v7 and 1v5 lines increases with the projected distance to the suspected main heating source I. Projection effects along the line of sight could explain the temperature gradient as produced by source I. However, the large luminosity required for source I, >5 10^5 Lsolar, to explain the 1v5 line suggests that external heating by this source may not dominate the heating of the HC. Simple model calculations of the vibrationally excited emission indicate that the HC can be internally heated by a source with a luminosity of 10^5 Lsolar, located 1.2'' SW of the 1v5 line peak (1.8'' south of source I). We also report the first detection of high-velocity gas from vibrationally excited HC3N emission. Based on excitation arguments we conclude that the main heating source is also driving the molecular outflow. We speculate that all the data presented in this letter and the IR images are consistent with a young massive protostar embedded in an edge-on disk.Comment: 13 pages, 3 figures, To be published in Ap.J. Letter

Relação entre a resistência do solo à penetração determinada por dois métodos e a pressão de pastejo, em um sistema de integração lavoura-pecuária.

Em pastagens constituídas por forrageiras tropicais perenes, o impacto das pressões de pastejo sobre o grau de compactação do solo tem sido pouco estudado. Com o objetivo de avaliar o efeito da pressão de pastejo sobre a resistência a penetração (RP), determinada por dois métodos, em um sistema de iLP, implantou-se um experimento sobre um Latossolo Vermelho distroférrico. As pressões de pastejo equivaleram a 6,88; 9,38; e 16,47 unidades animais por hectare, aplicadas numa pastagem de Brachiaria brizantha durante 19 dias. Esses tratamentos foram comparados a uma testemunha sem pastejo. Amostras indeformadas de solo, coletadas nas camadas de 0,0-0,05; 0,05-0,1; 0,1-0,2; e 0,2-0,3 m e equilibradas a uma tensão de 100 kPa, foram utilizadas para a determinação da RP em laboratório, por meio de um penetrômetro estático de bancada. Nessas mesmas profundidades, determinou-se a RP a campo, mediante o uso de um penetrômetro de impacto modelo IAA/Planalsucar- Stolf. Independentemente da pressão de pastejo, o pisoteio bovino aumentou a RP na camada de 0,0- 0,1 m. Na maior pressão de pastejo (16,47 UA ha-1), o pisoteio aumentou a RP a maiores profundidades (0,1-0,2 m). A magnitude dos valores de RP, assim como a resposta dos mesmos às pressões de pastejo, variaram em função do penetrômetro utilizado (dinâmico ou estático de bancada)

Diffusion dynamics on multiplex networks

We study the time scales associated to diffusion processes that take place on multiplex networks, i.e. on a set of networks linked through interconnected layers. To this end, we propose the construction of a supra-Laplacian matrix, which consists of a dimensional lifting of the Laplacian matrix of each layer of the multiplex network. We use perturbative analysis to reveal analytically the structure of eigenvectors and eigenvalues of the complete network in terms of the spectral properties of the individual layers. The spectrum of the supra-Laplacian allows us to understand the physics of diffusion-like processes on top of multiplex networks.Comment: 6 Pages including supplemental material. To appear in Physical Review Letter

Whey protein gelation: the effect of tryptic hydrolysis

The ability of whey proteins (WP) to form heat induced gels and provide texture is desirable for some “solid like” foods like processed meat, dairy and bakery products. However, this property limits the application of whey proteins in “liquid like” foods including beverages, baby formula and salad dressings [1]. Enzymatic hydrolysis impairs the gelation ability and improves the thermal stability of WP and can be used to expand the applications of WP [2]. From a dietary point of view, the use of whey protein hydrolysates instead of the “whole” protein isolates is interesting to reduce alle rgenicity or improve digestibility. Whey protein hydrolysates are also a important source of bioactive peptides liberated, from native proteins, during the hydrolysis. Once liberated, peptides may act as regulatory compounds with hormonelike activity [3]. In this work, our main objective is to model the gelling properties of whey protein tryptic hydrolysates (WPTH) as a function of the degree of hydrolysis and the protein concentration. An experimental design was applied where protein concentration range between 10 and 17 % (w/w) and hydrolysis degree range between 0,9 and 4,2 %, according to pH-stat methodology. The rheological behaviour of WPTH during heat gelling under small deformation oscillatory shear was investigated using a controlled stress rheometer AR2000 (TA Instruments). Empirical quadratic models were extracted from the experimental results. The statistical results show a dramatic effect of enzymatic hydrolysis on the gelling behaviour and on the gel properties. This study suggests that enzymatic hydrolysates can be designed for specific food formulations according to the desired gel (meat, dairy or bakery products) or liquid character (beverages, salad dressings)

Classical Tensors and Quantum Entanglement I: Pure States

The geometrical description of a Hilbert space asociated with a quantum system considers a Hermitian tensor to describe the scalar inner product of vectors which are now described by vector fields. The real part of this tensor represents a flat Riemannian metric tensor while the imaginary part represents a symplectic two-form. The immersion of classical manifolds in the complex projective space associated with the Hilbert space allows to pull-back tensor fields related to previous ones, via the immersion map. This makes available, on these selected manifolds of states, methods of usual Riemannian and symplectic geometry. Here we consider these pulled-back tensor fields when the immersed submanifold contains separable states or entangled states. Geometrical tensors are shown to encode some properties of these states. These results are not unrelated with criteria already available in the literature. We explicitly deal with some of these relations.Comment: 16 pages, 1 figure, to appear in Int. J. Geom. Meth. Mod. Phy