The Hamiltonian BRST quantization of a noncommutative nonabelian gauge theory and its Seiberg-Witten map

We consider the Hamiltonian BRST quantization of a noncommutative non abelian gauge theory. The Seiberg-Witten map of all phase-space variables, including multipliers, ghosts and their momenta, is given in first order in the noncommutative parameter $\theta$. We show that there exists a complete consistence between the gauge structures of the original and of the mapped theories, derived in a canonical way, once we appropriately choose the map solutions.Comment: 10 pages, Latex. Address adde

Assessing the toxicity of safer by design CuO surface-modifications using terrestrial multispecies assays

Safer by design (SBD) modifications of nanomaterials (NMs) have been pursued, aiming to maintain functionality and yet reduce hazard and support sustainable nanotechnology. The present case study involves copper oxide nanomaterials (CuO NMs) used in paint that have been surface modified by a SBD approach to particles coated with citrate (CIT-), ascorbate (ASC-), polyethylenimine (PEI+), and polyvinylpyrrolidone (PVP). We assessed the effect of the 4 different surface modified (CIT, ASC, PVP and PEI) NMs plus the pristine non-coated (PRI NM) and a Cu salt (CuCl2), using the soil multispecies test system (samples at 28-56-84 days). Further, the species were tested individually, and Cu was measured in the test media (soil and soil solution) and organisms. There was a potential relationship with zeta potential, and toxicity of CuO NMs was as follows: -PEI (+28 mV) caused the least impact, -ASC and -CIT (-17 mV, -18 mV) the most, while PVP and PRI (-8 mV, -9 mV) caused an intermediate response. Differences were not explained by the contribution of soluble Cu. Coating interfered with the release of Cu2+ and/or the activation of copper regulators and detoxification mechanisms in the organisms, i.e. time to reach some kind of stability in organisms' uptake was shorter for -ASC and longer for -PVP during prolonged time. Thus, one of the main findings is that NMs hazard assessment requires long term testing to understand predicted effects across materials. Further, the coverage using a multispecies approach offers increased relevance and a more ecosystem qualified response.publishe

Exciton-polariton mediated interaction between two nitrogen-vacancy color centers in diamond using two-dimensional transition metal dichalcogenides

In this paper, starting from a quantum master equation, we discuss the interaction between two negatively charged nitrogen-vacancy color centers in diamond via exciton-polaritons propagating in a two-dimensional transition metal dichalcogenide layer in close proximity to a diamond crystal. We focus on the optical 1.945 eV transition and model the nitrogen-vacancy color centers as two-level (artificial) atoms. We find that the interaction parameters and the energy-level renormalization constants are extremely sensitive to the distance of the nitrogen-vacancy centers to the transition-metal dichalcogenide layer. Analytical expressions are obtained for the spectrum of the exciton-polaritons and for the damping constants entering the Lindblad equation. The conditions for occurrence of exciton mediated superradiance are discussed.- B.A. and N.M.R.P acknowledge support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020. B.A. further acknowledges support from FCT through Grant No. CEECIND/02936/2017. N.M.R.P. acknowledges support from the European Commission through the project Graphene-Driven Revolutions in ICT and Beyond (Ref. No. 881603, CORE 3), COMPETE 2020, PORTUGAL 2020, FEDER and the FCT through Project No. POCI-01-0145-FEDER-028114

Evaluation of a Brazilian fuel alcohol yeast strain for Scotch whisky fermentations

Traditionally, distilling companies in Scotland have employed a very limited number of yeast strains in the production of alcohol for Scotch whiskies. Recent changes such as the decline in availability of brewers’ yeast as a secondary yeast strain and the availability of yeast in different formats (e.g., dried and cream yeast as alternatives to compressed yeast) have promoted interest in alternative Scotch whisky distilling yeasts. In previous work, we investigated different strains of yeasts, specifically Brazilian yeasts which had been isolated from and used in fuel alcohol distilleries. One of the Brazilian yeasts (CAT 1) showed a comparable fermentation performance and superior stress tolerance compared with a standard commercial Scotch whisky distilling yeast (M Type). The Brazilian CAT 1 yeast isolate was further assessed in laboratory scale fermentations and subsequent new make spirit was subjected to sensory analyses. The spirits produced using the Brazilian strain had acceptable flavour profiles and exhibited no sensory characteristics that were atypical of Scotch whisky new make spirit. This study highlights the potential of exploiting yeast biodiversity in traditional Scotch whisky distillery fermentation processes

Two limit cases of twisted hBN bilayers and their excitonic response

In this paper, we discuss the optical response due to the excitonic effect of two types of hBN bilayers: AB and AA′. Understanding the properties of these bilayers is of great utility to the study of twisted bilayers at arbitrary angles since these two configurations correspond to the limit cases of 0∘ and 60∘ rotation. To obtain the excitonic response, we present a method to solve a four-band Bethe-Salpeter equation by casting it into a one-dimensional problem, thus greatly reducing the numerical burden of the calculation when compared with strictly two-dimensional methods. We find results in good agreement with ab initio calculations already published in the literature for the AA′ bilayer, and predict the excitonic conductivity of the AB bilayer, which remains largely unstudied. The main difference in the conductivity of these two types of bilayers is the appearance of a small, yet well-resolved resonance between two larger ones in the AB configuration. This resonance is due to a mainly interlayer exciton, and is absent in the AA′ bilayer. Also, the conductivity of the AB bilayer is due to both intralayer and interlayer excitons and is dominated by p-states, while intralayer s-states are the relevant ones for the AA′ configuration, like in a monolayer. The effect of introducing a bias in the AA′ bilayer is also discussed.B.A., R.M.R and N.M.R.P acknowledge support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020. J.C.G.H. acknowledges the Center of Physics for a grant funded by the UIDB/04650/2020 strategic project. B.A. and N.M.R.P acknowledge support from FCT-Portugal through Project EXPL/FIS-MAC/0953/2021. B.A. further acknowledges funding from FCT-Portugal via Grant CEECIND/02936/2017. R.M.R. and N.M.R.P. also acknowledge support from the European Commis sion through the project GrapheneDriven Revolutions in ICT and Beyond (Ref. No. 881603, CORE 3) and the project PTDC/FIS-MAC/2045/2021. N.M.R.P. further acknowledges COMPETE 2020, PORTUGAL 2020, FEDER and the FCT through projects POCI-01-0145-FEDER-028114, POCI-01-0145-FEDER-02888 and PTDC/NAN-OPT/29265/2017

Downbeat nystagmus elicited by eyelid closure

We describe a patient with downbeat nystagmus (DBN) evoked only by eye closure. Brain and spinal cord magnetic resonance imaging revealed a T2 paramedian lesion in the left lower basis pontis and other white matter lesions consistent with multiple sclerosis. One potential mechanism for DBN in this case involves transverse ephaptic spread of excitation from areas that subserve coordinated lid closure to the decussating ventral tegmental tract.info:eu-repo/semantics/publishedVersio

Características físicas e morfológicas do sêmen de touros da raça nelore confinados e tratados com somatotrofina bovina recombinante (r-bST).

Edição dos resumos da 20. Reunião Anual da Sociedade Brasileira de Tecnologia de Embriões, Araxá, MG, agosto 2006

From Bloch Oscillations to a Steady-State Current in Strongly Biased Mesoscopic Devices

It has long been known that quantum particles in a periodic lattice exhibit an oscillatory motion that is solely driven by a constant and uniform force field. In a strongly biased mesoscopic device, this would appear as an ongoing time-dependent current oscillation (a Bloch oscillation) but, even when electrons can move coherently and without scattering, a steady-state regime of charge transport (a Landauer current) have been seen to quickly emerge. Here, we theoretically investigate the non-equilibrium current dynamics of a strongly biased two-terminal mesoscopic device, in order to show that such a system can exhibit Bloch oscillations as a transient regime that relaxes into a Landauer steady-state from charge being drained into the leads. Analytical results from the one-dimensional Wannier-Stark ladder problem are combined with numerical quantum time-evolution of a tight-binding toy model with finite leads to characterize the decay times of transient Bloch oscillations and establish the conditions under which they can occur.Comment: Preliminary Version (13 pages + 12 Figures). Comments and Suggestions are Welcome

Análise comparativa da eficácia de dois tipos de fibras de aço no reforço de elementos de betão

Duas extensas campanhas de ensaios experimentais foram efectuadas no sentido de se avaliar o desempenho de dois tipos de fibras de aço no comportamento à flexão e à compressão de betões de custo competitivo reforçados com fibras de aço para pavimentos de edifícios industriais. Os resultados obtidos são apresentados e analisados