Confining potential in a color dielectric medium with parallel domain walls

We study quark confinement in a system of two parallel domain walls interpolating different color dielectric media. We use the phenomenological approach in which the confinement of quarks appears considering the QCD vacuum as a color dielectric medium. We explore this phenomenon in QCD_2, where the confinement of the color flux between the domain walls manifests, in a scenario where two 0-branes (representing external quark and antiquark) are connected by a QCD string. We obtain solutions of the equations of motion via first-order differential equations. We find a new color confining potential that increases monotonically with the distance between the domain walls.Comment: RevTex4, 5 pages, 1 figure; version to appear in Int. J. Mod. Phys.

Working-class royalty: bees beat the caste system

The struggle among social classes or castes is well known in humans. Here, we show that caste inequality similarly affects societies of ants, bees and wasps, where castes are morphologically distinct and workers have greatly reduced reproductive potential compared with queens. In social insects, an individual normally has no control over its own fate, whether queen or worker, as this is socially determined during rearing. Here, for the first time, we quantify a strategy for overcoming social control. In the stingless bee Schwarziana quadripunctata, some individuals reared in worker cells avoid a worker fate by developing into fully functional dwarf queens

Radiation exposure awareness from patients undergoing nuclear medicine diagnostic 99mTc-MDP bone scans and 2-deoxy-2-(18F) fluoro-D-glucose PET/computed tomography scans

INTRODUCTION: Medical imaging is on average the largest source of artificial radiation exposure worldwide. This study seeks to understand patient's awareness of radiation exposure derived from nuclear medicine diagnostic scans and assess if current information provided by leaflets is adequate. METHODS: Single-centre cross-sectional questionnaire study applied to bone scan and FDG PET/computed tomography patients, at a nuclear medicine and PET/computed tomography department over a 15-week period in 2018. Questionnaires on dose comparators were designed in collaboration with patients, public, and experts in radiation exposure. Qualitative data were analysed using thematic analysis and quantitative data using SPSS (V. 24). RESULTS: A total of 102 questionnaires were completed (bone scan = 50; FDG PET/computed tomography = 52). Across both groups, 33/102 (32.4%) patients reported having a reasonable understanding of nuclear medicine and 21/102 (20.6%) reported a reasonable knowledge of ionising radiations. When asked to compare the exposure dose of respective scans with common comparators 8/50 (16%) of bone scan patients and 11/52 (21.2%) FDG PET/computed tomography answered correctly. On leaflet information, 15/85 (17.6%) patients reported the leaflets do not provide enough information on radiation exposure and of these 10/15 (66.7%) commented the leaflets should incorporate more information on radiation exposure dose. CONCLUSION: More observational and qualitative studies in collaboration with patients are warranted to evaluate patients' understanding and preferences in communication of radiation exposure from nuclear medicine imaging. This will ensure communication tools and guidelines developed to comply with ionising radiation (medical exposure) regulation 2017 are according to patients needs and preferences

Marcadores morfológicos em coqueiros (Cocos nucifera L.): coloracão do coleto.

Os marcadores de coloracao do coleto da plantula do coqueiro sao utilizados na certificacao de cruzamentos, baseado na heranca genetica das cores amarela, verde e marrom do coqueiro. Sua adequacao na certificacao e questionada.bitstream/item/44464/1/CPATC-DOCUMENTOS-7-MARCADORES-MORFOLOGICOS-EM-COQUEIROS-COCOS-NUCIFERA-L-COLORACAO-DO-COLETO-FL-1.pd

Quantum Hall resistance standards from graphene grown by chemical vapor deposition on silicon carbide

Replacing GaAs by graphene to realize more practical quantum Hall resistance standards (QHRS), accurate to within $10^{-9}$ in relative value, but operating at lower magnetic fields than 10 T, is an ongoing goal in metrology. To date, the required accuracy has been reported, only few times, in graphene grown on SiC by sublimation of Si, under higher magnetic fields. Here, we report on a device made of graphene grown by chemical vapour deposition on SiC which demonstrates such accuracies of the Hall resistance from 10 T up to 19 T at 1.4 K. This is explained by a quantum Hall effect with low dissipation, resulting from strongly localized bulk states at the magnetic length scale, over a wide magnetic field range. Our results show that graphene-based QHRS can replace their GaAs counterparts by operating in as-convenient cryomagnetic conditions, but over an extended magnetic field range. They rely on a promising hybrid and scalable growth method and a fabrication process achieving low-electron density devices.Comment: 12 pages, 8 figure

Recomendações técnicas para obtenção de sementes híbridas de coqueiro.

Condições ecólogicas requeridas, plantas progenitoras, anões, anão amarelo, anão vermelho, anão verde, gigantes, biologia floral, métodos, coleta e preparo de polen, coleta, secagem e tamisagem, condicionamento, emasculação das plantas, polinização, controles.bitstream/item/43932/1/CPATC-DOCUMENTOS-4-RECOMENDACOES-TECNICAS-PARA-OBTENCAO-DE-SEMENTES-HIBRIDAS-DE-COQUEIRO-FL-13122.pd

Resposta do milheto comum a doses de nitrogênio em planossolo típico no litoral sul do Rio Grande do Sul.

bitstream/item/31615/1/comunicado86.pd

Comportamento alimentar de Scaptotrigona bipunctata (Hymenoptera, Apidae, Meliponini) em três Municípios do Estado do Ceará.

As abelhas sem ferrão Scaptotrigona bipunctata tem uma ampla distribuição no território brasileiro, inclusive no Estado do Ceará, e apresentam um comportamento generalista de coleta de alimento floral em uma grande variedade de espécies vegetais. Com o objetivo de conhecer as plantas visitadas por S. bipunctata foi realizado um trabalho de identificação da flora fornecedora de recursos tróficos. As amostras de pólen foram coletadas diretamente dos potes de alimento de S. bipunctata em meliponários nos municípios de Fortaleza, Horizonte e Maracanaú. As coletas contaram com nove, doze e três repetições respectivamente. As análises polínicas foram conduzidas ao Laboratório de Abelha s da UFC. Para a identificação dos grãos de pólen foram montadas triplicatas de lâminas seguindo a metodologia de Miranda e Andrade (1990). Após a identificação dos tipos polínicos, foi realizada uma contagem de 300 grãos de pólen por repetição e foram calculadas as médias e os desvios padrões. Os resultados mostraram que as abelhas coletaram pólen de cinco espécies em Horizonte e Maracanaú: Cássia (Cássia fistula ), Guaxuma (Waltheria brachypetala ), Juazeiro (Zizyphus joazeiro), Sabiá (Mimosa caesalpinifolia) e Vassourinha de botão (Spermacoce verticillata). Vassourinha de botão foi a espécie dominante em Horizonte e Guaxuma em Maracanaú. Em Fortaleza, os tipos polínicos encontrados foram: Acácia (Acacia glomerosa), Cássia (C. fistula), Coqueiro (Cocus nucifera), Guaxuma (W. brachypetala), Juazeiro (Z. joazeiro ), Mamona (Ricinus communis), Mutre (Aloysia virgata), Quebra-panela (Alternanthera tenella), Sabiá(M. caesalpinifolia) e Vassourinha de botão (S. verticillata). O pólen dominante nas amostras de Fortaleza foram de Mamona ( R. communis)