13,253 research outputs found
Astrometry of mutual approximations between natural satellites. Application to the Galilean moons
Typically we can deliver astrometric positions of natural satellites with
errors in the 50-150 mas range. Apparent distances from mutual phenomena, have
much smaller errors, less than 10 mas. However, this method can only be applied
during the equinox of the planets. We developed a method that can provide
accurate astrometric data for natural satellites -- the mutual approximations.
The method can be applied when any two satellites pass close by each other in
the apparent sky plane. The fundamental parameter is the central instant
of the passage when the distances reach a minimum.
We applied the method for the Galilean moons. All observations were made with
a 0.6 m telescope with a narrow-band filter centred at 889 nm with width of 15
nm which attenuated Jupiter's scattered light. We obtained central instants for
14 mutual approximations observed in 2014-2015. We determined with an
average precision of 3.42 mas (10.43 km). For comparison, we also applied the
method for 5 occultations in the 2009 mutual phenomena campaign and for 22
occultations in the 2014-2015 campaign. The comparisons of determined by
our method with the results from mutual phenomena show an agreement by less
than 1-sigma error in , typically less than 10 mas. This new method is
particularly suitable for observations by small telescopes.Comment: 13 pages, 11 figures and 8 tables. Based on observations made at the
Laborat\'orio Nacional de Astrof\'isica (LNA), Itajub\'a-MG, Brazi
Levantamento do nematóide das galhas (Meloidogyne spp.) em arroz irrigado na região Sul do Brasil.
bitstream/item/30488/1/boletim-87.pd
Cooperative localization-delocalization in the high Tc cuprates
The intrinsic metastable crystal structure of the cuprates results in local
dynamical lattice instabilities, strongly coupled to the density fluctuations
of the charge carriers. They acquire in this way simultaneously both,
delocalized and localized features. It is responsible for a partial fractioning
of the Fermi surface, i.e., the Fermi surface gets hidden in a region around
the anti-nodal points, because of the opening of a pseudogap in the normal
state, arising from a partial charge localization. The high energy localized
single-particle features are a result of a segregation of the homogeneous
crystal structure into checker-board local nano-size structures, which breaks
the local translational and rotational symmetry. The pairing in such a system
is dynamical rather than static, whereby charge carriers get momentarily
trapped into pairs in a deformable dynamically fluctuating ligand environment.
We conclude that the intrinsically heterogeneous structure of the cuprates must
play an important role in this type of superconductivity.Comment: 14 pages, 8 figures, Proceedings of the "International Conference on
Condensed Matter Theories", Quito, 2009 Int. J. Mod. Phys. B 2010 (Accepted
The effects of sodium hypochlorite against selected drinking water-isolated bacteria in planktonic and sessile states
Chlorine is the most commonly used agent for general disinfection, particularly for microbial growth control in drinking water distribution systems. The goals of this study were to understand the effects of chlorine, as sodium hypochlorite (NaOCl), on bacterial membrane physicochemical properties (surface charge, surface tension and hydrophobicity) and on motility of two emerging pathogens isolated from drinking water, Acinetobacter calcoaceticus and Stenotrophomonas maltophilia. The effects of NaOCl on the control of single and dual-species monolayer adhered bacteria (2 h incubation) and biofilms (24 h incubation) was also assessed. NaOCl caused significant changes on the surface hydrophobicity and motility of A. calcoaceticus, but not of S. maltophilia. Planktonic and sessile S. maltophilia were significantly more resistant to NaOCl than A. calcoaceticus. Monolayer adhered co-cultures of A. calcoaceticus-S. maltophilia were more resilient than the single species. Oppositely, dual species biofilms were more susceptible to NaOCl than their single species counterparts. In general, biofilm removal and killing demonstrated to be distinct phenomena: total bacterial viability reduction was achieved even if NaOCl at the higher concentrations had a reduced removal efficacy, allowing biofilm reseed. In conclusion, understanding the antimicrobial susceptibility of microorganisms to NaOCl can contribute to the design of effective biofilm control strategies targeting key microorganisms, such as S. maltophilia, and guarantying safe and high-quality drinking water. Moreover, the results reinforce that biofilms should be regarded as chronic contaminants of drinking water distribution systems and accurate methods are needed to quantify their presence as well as strategies complementary/alternative to NaOCl are required to effectively control the microbiological quality of drinking water.This work was financially supported by: Project POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy – LEPABE funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia/MEC: Project POMACEA–Inn-INDIGO/0001/2014, SFRH/BD/103810/2014 and SFRH/BPD/81982/2011
Influence of surface copper content on Stenotrophomonas maltophilia biofilm control using chlorine and mechanical stress
This work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10mg l1 of free chlorine for 10min, an increased shear stress (a fluid velocity of 1.5m s1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure.This work was the result of the projects: UID/EQU/00511/2019 – Laboratory for Process Engineering, Environment, Biotechnology and Energy – LEPABE funded by national funds through FCT/MCTES (PIDDAC); POCI-01-0145-FEDER-030219; POCI-01-0247-FEDER-035234; POCI-01-0247-FEDER-033298 - funded by FEDER funds through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES; NORTE-01-0145-FEDER-000005 – LEPABE-2-ECO-INNOVATION, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Grant attributed by Portuguese Foundation for Science and Technology – FCT – to Inês Gomes
(SFRH/BD/103810/2014) and to Manuel Simoes (SFRH/BSAB/150379/2019).info:eu-repo/semantics/publishedVersio
Crescimento de Eucalyptus benthamii submetido à aplicação de lama de cal e cinza de madeira.
bitstream/item/145220/1/CT-373-Maeda.pd
Non Abelian Sugawara Construction and the q-deformed N=2 Superconformal Algebra
The construction of a q-deformed N=2 superconformal algebra is proposed in
terms of level 1 currents of quantum affine
Lie algebra and a single real Fermi field. In particular, it suggests the
expression for the q-deformed Energy-Momentum tensor in the Sugawara form. Its
constituents generate two isomorphic quadratic algebraic structures. The
generalization to is also proposed.Comment: AMSLATEX, 21page
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