Spontaneous emission in inertial and dissipative nematic liquid crystals: the role of critical phenomena.

We develop a rigorous, field-theoretical approach to the study of spontaneous emission in inertial and dissipative nematic liquid crystals (LCs), disclosing an alternative application of the massive Stückelberg gauge theory to describe critical phenomena in these systems. This approach allows one not only to unveil the role of phase transitions in the spontaneous emission in LCs but also to make quantitative predictions for quantum emission in realistic nematics of current scientific and technological interest in the field of metamaterials. Specifically, we predict that one can switch on and off quantum emission in LCs by varying the temperature in the vicinities of the crystalline-to-nematic phase transition, for both the inertial and dissipative cases. We also predict from first principles the value of the critical exponent that characterizes such a transition, which we show not only to be independent of the inertial or dissipative dynamics, but also to be in good agreement with experiments. We determine the orientation of the dipole moment of the emitter relative to the nematic director that inhibits spontaneous emission, paving the way to achieve directionality of the emitted radiation, a result that could be applied in tuneable photonic devices such as metasurfaces and tuneable light sources.

Morbidity and mortality in Holstein calves from birth to 145 days of age on a large dairy farm in Brazil / Morbidade e mortalidade em bezerras da raça Holandesa do nascimento aos 145 dias de vida, em uma grande fazenda produtora de leite no Brasil

The present study aimed to investigate the morbidity and mortality associated with the most common diseases during the rearing period of Holstein calves in a high-production dairy farm. The calves (n = 600) were allocated to three groups based on age: G1 (1-7 days, n = 216), G2 (30-40 days, n = 188), and G3 (69-85 days, n = 196). They were evaluated over 60 days at eight different times. The morbidity rates were 47.67% (286/600) for diarrhea, 73.00% (438/600) for bovine respiratory disease (BRD), and 3.83% (23/600) for umbilical inflammation (UI). The mortality rate was 2.33% (14/600) for all the animals studied. The morbidity differed in the groups, with higher rates of diarrhea (78.85%, 166/216) and UI (6.94%, 15/216) in G1, and the highest rate of BRD in G3 (79.59%, 156/196). Diarrhea was associated with the occurrence of BRD in G1 and G2. Even in farms with good management practices, there is high morbidity associated with diarrhea and BRD, with the morbidity rate for diarrhea decreasing and that for BRD increasing as the animals get older. In addition, diarrhea is an important risk factor for BRD, especially in younger animals.(AU)

O presente estudo objetivou investigar a morbidade e a mortalidade associadas às doenças mais comuns no período de criação de bezerras da raça Holandesa, em uma fazenda leiteira de alta produção. As bezerras (n = 600) foram alocadas em três grupos de acordo com a idade: G1 (1-7 dias, n = 216); G2 (30-40 dias, n = 188); G3 (69-85 dias, n = 196). Os animais foram avaliados durante 60 dias, em oito momentos diferentes. A morbidade foi de 47,67% (286/600) para diarreia, 73,00% (438/600) para doença respiratória bovina (DRB) e 3,83% (23/600) para inflamação umbilical (IU). A taxa de mortalidade foi de 2,33% (14/600), para o total de animais avaliados. A morbidade foi diferente entre os grupos, com maior frequência de diarreia (78,85%, 166/216) e IU (6,94%, 15/216) no G1, sendo a maior ocorrência de DRB no G3 (79,59%, 156/196). A diarreia foi associada à DRB no G1 e no G2. Mesmo em fazendas com boas práticas de manejo, há alta morbidade por diarreia e DRB, com a taxa de morbidade por diarreia diminuindo e a de DRB aumentando à medida que os animais envelhecem. Além disso, a diarreia é um importante fator de risco para DRB, especialmente em animais mais jovens.(AU)

Enantioselection and chiral sorting of single microspheres using optical pulling forces.

We put forward a novel, twofold scheme that enables, at the same time, all-optical enantioselection and sorting of single multipolar chiral microspheres based on optical pulling forces exerted by two non-collinear, non-structured, circularly polarized light sources. Our chiral resolution method can be externally controlled by varying the angle between their incident wavevectors, allowing for fine-tuning of the range of chiral indices for enantioselection. Enantioselectivity is achieved by choosing angles such that only particles with the same handedness of the light sources are pulled. This proposal allows one to achieve all-optical sorting of chiral microspheres with arbitrarily small chiral parameters, thus outperforming current optical methods.

Modeling anisotropic magnetoresistance in layered antiferromagnets.

We have investigated the electronic transport and the anisotropic magnetoresistance in systems consisting of pairs of antiferromagnetically aligned layers separated by a non-magnetic layer, across which an antiferromagnetic coupling between the double layers is established. Calculations have been performed within the framework of the tight-binding model, taking into account the exchange coupling within the ferromagnetic layers and the Rashba spin-orbit interaction. Conductivities have been evaluated in the ballistic regime, based on Kubo formula. We have systematically studied the dependence of the conductivity and of the anisotropic magnetoresistance on several material and structural parameters, such as the orientation of the magnetic moments relative to the crystalline axis, band filling, out-of-plane hopping and spin-orbit parameter.

Molding the flow of light with a magnetic field: plasmonic cloaking and directional scattering.

We investigate electromagnetic (EM) scattering and plasmonic cloaking in a system composed of a dielectric cylinder coated with a magneto-optical shell. In the long-wavelength limit we demonstrate that the application of an external magnetic field can not only switch on and off the cloaking mechanism but also mitigate losses, as the absorption cross section is shown to drop sharply precisely at the cloaking operation frequency band. We also show that the angular distribution of the scattered radiation can be effectively controlled by applying an external magnetic field, allowing for a swift change in the scattering pattern. By demonstrating that these results are feasible with realistic, existing magneto-optical materials, such as graphene epitaxially grown on SiC, we suggest that magnetic fields could be used as effective, versatile external agents to tune plasmonic cloaks and to dynamically control EM scattering in an unprecedented way. We hope that these results may find use in disruptive photonic technologies.

Tuning plasmonic cloaks with an external magnetic field.

We propose a mechanism to actively tune the operation of plasmonic cloaks with an external magnetic field by investigating electromagnetic scattering by a dielectric cylinder coated with a magneto-optical shell. In the long wavelength limit, we show that the presence of a magnetic field may drastically reduce the scattering cross section at all observation angles. We demonstrate that the application of magnetic fields can modify the operation wavelength without the need of changing material and/or geometrical parameters. We also show that applied magnetic fields can reversibly switch on and off the cloak operation. These results, which could be achieved for existing magneto-optical materials, are shown to be robust to material losses, so that they may pave the way for developing actively tunable, versatile plasmonic cloaks.

Short-term effect of leflunomide in patients with Takayasu arteritis: an observational study.

OBJECTIVES: To evaluate the efficacy of leflunomide in controlling disease activity in patients with Takayasu arteritis (TA) refractory or intolerant to conventional treatment. METHODS: We conducted a prospective open-label study of 15 TA patients (mean age 36.2 years) with active disease based on clinical assessment, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and magnetic resonance angiography (MRA). Patients received leflunomide 20 mg/day for at least 6 months and were followed up for a mean of 9.1 months. Adverse events attributable to leflunomide were recorded. RESULTS: At baseline, 14 TA patients had active disease despite therapy with corticosteroids and immunosuppressive agents, while one patient had intolerance to current treatment. In the follow-up visit, we found a significant decrease in the frequency of patients with active TA (93% vs. 20%, p = 0.002), in the mean daily dose of prednisone (34.2 vs. 13.9 mg, p < 0.001) and in the median values of ESR (29.0 vs. 27.0 mm/h, p = 0.012) and CRP (10.3 vs. 5.3 mg/L, p = 0.012). Two patients (13.3%) developed new angiographic lesions in the follow-up MRA. Three patients (20%) experienced mild adverse events during the study and none discontinued therapy. CONCLUSIONS: This is the first open-label study to demonstrate improvement in disease activity and acute phase reactants with 20 mg/day of leflunomide in TA patients who were refractory or intolerant to conventional therapy with corticosteroids and immunosuppressive agents. Leflunomide was safe and a steroid-sparing effect was observed. A double-blind controlled study is desirable to confirm this finding.

Multiple antimicrobial resistance of gram-negative bacteria from natural oligotrophic lakes under distinct anthropogenic influence in a tropical region.

The aim of this study was to evaluate the resistance to ten antimicrobial agents and the presence of bla ( TEM1 ) gene of Gram-negative bacteria isolated from three natural oligotrophic lakes with varying degrees of anthropogenic influence. A total of 272 indigenous bacteria were recovered on eosin methylene blue medium; they were characterized for antimicrobial resistance and identified taxonomically by homology search and phylogenetic comparisons. Based on 16S ribosomal RNA sequences analysis, 97% of the isolates were found to be Gram-negative bacteria; they belonged to 11 different genera. Members of the genera Acinetobacter, Enterobacter, and Pseudomonas predominated. Most of the bacteria were resistant to at least one antimicrobial. The incidence of resistance to beta-lactams, chloramphenicol, and mercury was high, whereas resistance to tetracycline, aminoglycosides, and nalidixic acid was low. There was a great frequency of multiple resistances among the isolates from the three lakes, although no significant differences were found among the disturbed and reference lakes. The ampicillin resistance mechanism of 71% of the isolates was due to the gene bla ( TEM1 ). Our study suggests that multiresistant Gram-negative bacteria and the bla ( TEM1 ) gene are common in freshwater oligotrophic lakes, which are subject to different levels of anthropogenic inputs.

Probing Anderson localization of light via decay rate statistics.

We have studied the distribution of resonance widths P(Gamma) in one-, two-, and three-dimensional multiple light scattering systems. P(Gamma) should follow a universal power law P(Gamma) approximately Gamma(-1) in the localized regime as confirmed by extensive numerical calculations. This behavior can be interpreted as an unambiguous signature of exponential Anderson localization of light in open systems.

Magnetochiral scattering of light: optical manifestation of chirality.

We have investigated multiple scattering of light in systems subject to magnetochiral (MC) effects. Our medium consists of magneto-optically active dipoles placed in a chiral geometry under the influence of an external magnetic field. We have calculated the total and the differential scattering MC cross sections of this system, explicitly showing that they are proportional to pseudoscalar quantities. This provides an optical measure for the degree of chirality, a pseudoscalar g, of an arbitrary geometrical configuration of scatterers based on its scattering properties. We have calculated g for some simple chiral systems and we have even used it to probe the degree of optical chirality of random systems. Finally, we have compared g with other recently defined chiral measures in literature.

Vanishing of energy transport velocity and diffusion constant of electromagnetic waves in disordered magnetic media.

The energy transport velocity v(E) and the diffusion constant D of electromagnetic waves in the presence of randomly distributed ferromagnetic scatterers are studied. v(E) presents a strong dependence on the relative magnetic permeability mu and, unlike the nonmagnetic case, exhibits sharp drops in the small-particle limit and never coincides with the phase velocity v(p). Both v(E) and D exhibit an oscillatory dependence on mu and vanish for certain values of mu. Since mu of ferromagnetic scatterers strongly depends on the temperature and applied magnetic field, we suggest that these facts can be explored in technological applications.