Ward Identities and chiral anomalies for coupled fermionic chains

Coupled fermionic chains are usually described by an effective model written in terms of bonding and anti-bonding spinless fields with linear dispersion in the vicinities of the respective Fermi points. We derive for the first time exact Ward Identities (WI) for this model, proving the existence of chiral anomalies which verify the Adler-Bardeen non-renormalization property. Such WI are expected to play a crucial role in the understanding of the thermodynamic properties of the system. Our results are non-perturbative and are obtained analyzing Grassmann functional integrals by means of Constructive Quantum Field Theory methods.Comment: TeX file, 26 pages, 7 figures. Published version, new section added to answer referee remarks and derive the Ward Identites, no modifications in the main resul

Initial pseudo-steady state & asymptotic KPZ universality in semiconductor on polymer deposition

The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality in nonequilibrium phenomena, but clear experimental evidences of asymptotic 2D-KPZ statistics are still very rare, and far less understanding stems from its short-time behavior. We tackle such issues by analyzing surface fluctuations of CdTe films deposited on polymeric substrates, based on a huge spatio-temporal surface sampling acquired through atomic force microscopy. A \textit{pseudo}-steady state (where average surface roughness and spatial correlations stay constant in time) is observed at initial times, persisting up to deposition of $\sim 10^{4}$ monolayers. This state results from a fine balance between roughening and smoothening, as supported by a phenomenological growth model. KPZ statistics arises at long times, thoroughly verified by universal exponents, spatial covariance and several distributions. Recent theoretical generalizations of the Family-Vicsek scaling and the emergence of log-normal distributions during interface growth are experimentally confirmed. These results confirm that high vacuum vapor deposition of CdTe constitutes a genuine 2D-KPZ system, and expand our knowledge about possible substrate-induced short-time behaviors.Comment: 13 pages, 8 figures, 2 table

Ising t-J model close to half filling: A Monte Carlo study

Within the recently proposed doped-carrier representation of the projected lattice electron operators we derive a full Ising version of the t-J model. This model possesses the global discrete Z_2 symmetry as a maximal spin symmetry of the Hamiltonian at any values of the coupling constants, t and J. In contrast, in the spin anisotropic limit of the t-J model, usually referred to as the t-J_z model, the global SU(2) invariance is fully restored at J_z=0, so that only the spin-spin interaction has in that model the true Ising form. We discuss a relationship between those two models and the standard isotropic t-J model. We show that the low-energy quasiparticles in all three models share the qualitatively similar properties at low doping and small values of J/t. The main advantage of the proposed Ising t-J model over the t-J_z one is that the former allows for the unbiased Monte Carlo calculations on large clusters of up to 10^3 sites. Within this model we discuss in detail the destruction of the antiferromagnetic order by doping as well as the interplay between the AF order and hole mobility. We also discuss the effect of the exchange interaction and that of the next nearest neighbour hoppings on the destruction of the AF order at finite doping. We show that the short-range AF order is observed in a wide range of temperatures and dopings, much beyond the boundaries of the AF phase. We explicitly demonstrate that the local no double occupancy constraint plays the dominant role in destroying the magnetic order at finite doping. Finally, a role of inhomogeneities is discussed.Comment: 24 pages, 10 figure

Relación angular radiológica de las superficies articulares de la tibia en sujetos asintomáticos

Se efectuó un estudio radiológico para determinar la relación angular existente entre las superficies articulares proximal y distal de 108 tibias correspondientes a 54 pacientes asintomáticos, de edades entre 14 y 72 años (media: 29,8). La medición se llevó a cabo con un «cobbometro» de Oxford en proyección anteroposterior y lateral. El ángulo medio entre ambas superficies fue de 3,3 ± 2,6° (intervalo de confianza al 95%: 2,8-3,8°) en proyección anteroposterior y de 5,5 ± 3,9° (intervalo de confianza: 4,7-6,3°) en proyección lateral. Cuando se consideró para cada paciente, la diferencia media de esta relación angular entre las tibias derechas e izquierdas fue inferior a 0,5° en ambas proyecciones.The angular relationship between proximal and distal articular surfaces was determined, through an Oxford Cobbometer, in 108 tibiae of 54 asymptomalic patients aging 14 to 72 years (mean: 30). Mean angle between both surfaces was 3.3 ± 2.6° (95% confidence interval: 2.8-3.8°) for the anteroposterior view and 5.5 ± 3.9° (95% confidence interval: 4.7-6.3°) for the lateral view. When considered individually for each patient, mean difference of this angular relationship among right and left tibiae was lesser than 0.5° for both projections

Comportamento reológico de emulsões do tipo água-óleo de petróleos pesados: estudo experimental e avaliação de correlações empíricas

À medida que campos de petróleo envelhecem, em geral, a quantidade de água produzida aumenta. No meio poroso da rocha reservatório, água e óleo encontram-se segregados. Entretanto, os fluidos de um poço ao serem colocados em fluxo podem ser misturados entre si, em decorrência do intenso cisalhamento sofrido pelas fases e, consequentemente, levar ao surgimento de emulsões que apresentam elevada viscosidade. O aumento da viscosidade é indesejável, pois acarreta o emprego de equipamentos de maior capacidade de bombeio e, o consequente, aumento do custo final do óleo produzido. Outra desvantagem consiste na dificuldade de realização de cálculos termo-hidráulicos do escoamento de petróleo nas tubulações, imprescindíveis nas etapas de elaboração de projetos, pois, usualmente, os modelos empregados se valem do uso de correlações empíricas, as quais exigem o conhecimento das viscosidades dos fluidos, em especial da fase líquida. Incertezas nestes valores podem implicar em dimensionamentos errôneos de equipamentos. Neste trabalho foram escolhidas quatro amostras de petróleos pesados oriundos de campos terrestres do Norte Capixaba, com grau API entre 13 e 23, e foi empregada a técnica de planejamento de experimentos para identificação das variáveis com impacto significativo sobre as viscosidades relativas de emulsões do tipo água em óleo (A/O). A fração volumétrica da fase dispersa apresentou significância, enquanto, a temperatura e taxa de cisalhamento não apresentaram influência sobre as viscosidades relativas. Mediante testes adicionais foi possível comparar correlações empíricas propostas na literatura e concluir que as correlações de Brinkman (1952), Vand (1948) e Pal e Rhodes (1989), presentes em alguns dos principais simuladores de escoamento multifásico (OLGA®, PIPESIM®), ofereceram resultados satisfatórios para previsão do comportamento de emulsões produzidas por poços de óleos pesados

Experimental Observation of Quantum Correlations in Modular Variables

We experimentally detect entanglement in modular position and momentum variables of photon pairs which have passed through $D$-slit apertures. We first employ an entanglement criteria recently proposed in [Phys. Rev. Lett. {\bf 106}, 210501 (2011)], using variances of the modular variables. We then propose an entanglement witness for modular variables based on the Shannon entropy, and test it experimentally. Finally, we derive criteria for Einstein-Podolsky-Rosen-Steering correlations using variances and entropy functions. In both cases, the entropic criteria are more successful at identifying quantum correlations in our data.Comment: 7 pages, 4 figures, comments welcom

Spatial variability of litter temperature, relative air humidity and skin temperature of chicks in a commercial broiler house

ArticleThe thermal environment inside a broiler house has a great influence on animal welfare and productivity during the production phase. Among the importance of the chicken litter is the function of absorbing moisture, provide thermal insulation and provide a soft surface for broilers. The skin temperature is an important physiological parameter to quantify the thermal comfort of animals, its variations may occur as a function of thermal variables. So, the aim of this work was to analyse the magnitude and spatial variability of chicken litter temperature and relative humidity of the air and to correlate them with the spatial distribution of chicks’ skin surface temperature throughout the broiler house during the 7th, 14th and 21st days of the chicks’ life, using geostatistical techniques. The experiment was performed in a commercial broiler house located in the western mesoregion of Minas Gerais, Brazil, where 28,000 male Cobb chicks were housed. The heating system consisted of an industrial indirect-fired biomass furnace. The heated air was inflated by an AC motor, 2,206 W of power, 1,725 RPM. Geostatistical techniques were used through semivariogram analysis and isochore maps were generated through data interpolation by kriging. The semivariogram was fitted by the restricted maximum likelihood method. The used mathematical model was the spherical one. After fitting the semivariograms, the data were interpolated by ordinary kriging. The semivariograms along with the isochore maps allowed identifying the non-uniformity of spatial distribution of the broiler litter temperature throughout the broiler house for 3 days of chicks’ life. It was observed that skin surface presented a positive correlation with the litter temperature and a negative correlation with the air humidity. The semivariograms along with the isochore maps allowed identifying the non-uniformity of spatial distribution of the litter temperature, air humidity and skin temperature of chicks throughout the broiler aviary for the three days. In addition, the use of geostatistics and distribution maps made possible to identify different environmental conditions in regions inside the broiler house that may harm the development of chicks