Study of the bilinear biquadratic Heisenberg model on a honeycomb lattice via Schwinger bosons

We analyze the biquadratic bilinear Heisenberg magnet on a honeycomb lattice via Schwinger boson formalism. Due to their vulnerability to quantum fluctuations, non conventional lattices (kagome, triangular and honeycomb for example) have been cited as candidates to support spin liquid states. Such states without long range order at zero temperature are known in one-dimensional spin models but their existence in higher dimensional systems is still under debate. Biquadratic interaction is responsible for various possibilities and phases as it is well-founded for one-dimensional systems. Here we have used a bosonic representation to study the properties at zero and finite low temperatures of the biquadratic term in the two-dimensional hexagonal honeycomb lattice. The results show a ordered state at zero temperature but much more fragile than that of a square lattice; the behavior at finite low temperatures is in accordance with expectations.Comment: 14 pages, 5 figure

Testing CPT- and Lorentz-odd electrodynamics with waveguides

We study CPT- and Lorentz-odd electrodynamics described by the Standard Model Extension. Its radiation is confined to the geometry of hollow conductor waveguide, open along $z$. In a special class of reference frames, with vanishing both 0-th and $z$ components of the background field, $(k_{\rm AF})^\mu$, we realize a number of {\em huge and macroscopically detectable} effects on the confined waves spectra, compared to standard results. Particularly, if $(k_{\rm AF})^\mu$ points along $x$ (or $y$) direction only transverse electric modes, with $E_z=0$, should be observed propagating throughout the guide, while all the transverse magnetic, $B_z=0$, are absent. Such a strong mode suppression makes waveguides quite suitable to probe these symmetry violations using a simple and easily reproducible apparatus.Comment: 11pages, double-spacing, tex forma

Clonal expansion across the seas as seen through CPLP-TB database: A joint effort in cataloguing Mycobacterium tuberculosis genetic diversity in Portuguese-speaking countries.

Tuberculosis (TB) remains a major health problem within the Community of Portuguese Language Speaking Countries (CPLP). Despite the marked variation in TB incidence across its member-states and continued human migratory flux between countries, a considerable gap in the knowledge on the Mycobacterium tuberculosis population structure and strain circulation between the countries still exists. To address this, we have assembled and analysed the largest CPLP M. tuberculosis molecular and drug susceptibility dataset, comprised by a total of 1447 clinical isolates, including 423 multidrug-resistant isolates, from five CPLP countries. The data herein presented reinforces Latin American and Mediterranean (LAM) strains as the hallmark of M. tuberculosis populational structure in the CPLP coupled with country-specific differential prevalence of minor clades. Moreover, using high-resolution typing by 24-loci MIRU-VNTR, six cross-border genetic clusters were detected, thus supporting recent clonal expansion across the Lusophone space. To make this data available to the scientific community and public health authorities we developed CPLP-TB (available at http://cplp-tb.ff.ulisboa.pt), an online database coupled with web-based tools for exploratory data analysis. As a public health tool, it is expected to contribute to improved knowledge on the M. tuberculosis population structure and strain circulation within the CPLP, thus supporting the risk assessment of strain-specific trends

uma nova ferramenta de vigilância transnacional da tuberculose no espaço lusófono

A Tuberculose (TB) permanece um grave problema de saúde pública na Comunidade dos Países de Língua Portuguesa (CPLP). Apesar da ampla variância da incidência da TB nos seus estados-membro e de um fluxo migratório contínuo entre os países que integram este grupo, existe uma enorme lacuna no que diz respeito ao conhecimento da estrutura populacional conjunta do Mycobacterium tuberculosis e circulação de estirpes entre estes países. Para fazer face a esta necessidade, foi agregado e analisado o maior conjunto de dados respeitante à diversidade genotípica e resistência fenotípica na CPLP que compreende um total de 1447 isolados clínicos, incluindo 423 isolados multirresistentes de cinco países da CPLP. Por forma a tornar estes dados disponíveis para a comunidade científica e autoridades de saúde pública, foi desenvolvida a CPLP-TB (disponível em http://cplp-tb.ff.ulisboa.pt), uma base de dados disponível online e provida de aplicativos para análise exploratória do conteúdo. Como ferramenta de saúde pública, espera-se que venha a contribuir para um conhecimento mais aprofundado da estrutura populacional do M. tuberculosis e circulação de estirpes na CPLP de forma a apoiar a avaliação de risco e tendências específicas para diversos clones. Tuberculosis (TB) remains a major health problem within the Community of Portuguese Language Speaking Countries (CPLP). Despite the marked variation in TB incidence across its member-states and continued human migratory flux between countries, a considerable gap in the knowledge on the Mycobacterium tuberculosis population structure and strain circulation between the countries still exists. To address this, we have assembled and analyzed the largest CPLP M . tuberculosis molecular and drug susceptibility dataset, comprised by a total of 1447 clinical isolates, including 423 multidrug-resistant isolates, from five CPLP countries. To make this data available to the scientific community and public health authorities we developed CPLP-TB (available at http://cplp-tb.ff.ulisboa.pt), an online database coupled with web-based tools for exploratory data analysis. As a public health tool, it is expected to contribute to improved knowledge on the M. tuberculosis population structure and strain circulation within the CPLP, thus supporting the risk assessment of strain-specific trends.publishersversionpublishe

Discrete double core skyrmions in magnetic thin films

We study the Belavin–Polyakov double core skyrmions in two-dimensional isotropic Heisenberg ferromagnets on a discrete square lattice by means of spin dynamic simulations using periodic boundaries conditions. It is also investigated the presence of external in-plane magnetic fields and lattice defects. We have shown that these discrete skyrmions not cylindrically symmetric have a high degree of stability, similar to their continuum counterparts, even if small spatial inhomogeneities are present into the syste

CONDIÇÕES DO SOLO SOB APLICAÇÃO DE EFLUENTES DA BOVINOCULTURA LEITEIRA COMO FONTE DE IRRIGAÇÃO. SOIL CONDICTIONS WITH APPLICATION OF DAIRY CATTLE EFFLUENT BY IRRIGATION.

A degradação do meio ambiente é preocupante, dado a importância dos recursos naturais para avida no planeta. Com o crescente aumento do confinamento dos bovinos de leite esse problematem aumentado devido a grande produção de efluente. Assim, o presente trabalho teve como objetivo avaliar a contaminação do solo com irrigação de água residuária da bovinocultura leiteira. Aplicou-se a água residuária em vasos apenas com solo, dentro de ambiente protegido, sendo usado mais dois tratamentos, um com água residuária sem partículas sólidas, e outro sem partículas sólidas mais adubo superfosfato simples, além da testemunha. Os principais resultados encontrados foram: (1) a água residuária apresentou elevados teores de Cu e Fe, em relação a limites estabelecidos por órgãos nacionais e internacionais; (2) o solo mostrou níveis normais de marcro e micronutrientes, não apresentando contaminação por metais pesados. Assim, concluí-se que a utilização de água residuária da bovinocultura leitra para irrigação, não causou contaminação do solo.</p