12,076 research outputs found
On the far-infrared metallicity diagnostics: applications to high-redshift galaxies
In an earlier paper we modeled the far-infrared emission from a star-forming
galaxy using the photoionisation code CLOUDY and presented metallicity
sensitive diagnostics based on far-infrared fine structure line ratios. Here,
we focus on the applicability of the [OIII]88/[NII]122 microns line ratio as a
gas phase metallicity indicator in high redshift submillimetre luminous
galaxies. The [OIII]88/[NII]122 microns ratio is strongly dependent on the
ionization parameter (which is related to the total number of ionizing photons)
as well as the gas electron density. We demonstrate how the ratio of 88/$122
continuum flux measurements can provide a reasonable estimate of the ionization
parameter while the availability of the [NII]205 microns line can constrain the
electron density. Using the [OIII]88/[NII]122 microns line ratios from a sample
of nearby normal and star-forming galaxies we measure their gas phase
metallicities and find that their mass metallicity relation is consistent with
the one derived using optical emission lines. Using new, previously
unpublished, Herschel spectroscopic observations of key far-infrared fine
structure lines of the z~3 galaxy HLSW-01 and additional published measurements
of far-infrared fine structure lines of high-z submillimetre luminous galaxies
we derive gas phase metallicities using their [OIII]88/[NII]122 microns line
ratio. We find that the metallicities of these z~3 submm luminous galaxies are
consistent with solar metallicities and that they appear to follow the
mass-metallicity relation expected for z~3 systems.Comment: 10 pages, 7 figures, MNRAS in pres
The loop-quantum-gravity vertex-amplitude
Spinfoam theories are hoped to provide the dynamics of non-perturbative loop
quantum gravity. But a number of their features remain elusive. The best
studied one -the euclidean Barrett-Crane model- does not have the boundary
state space needed for this, and there are recent indications that,
consequently, it may fail to yield the correct low-energy -point functions.
These difficulties can be traced to the SO(4) -> SU(2) gauge fixing and the way
certain second class constraints are imposed, arguably incorrectly, strongly.
We present an alternative model, that can be derived as a bona fide
quantization of a Regge discretization of euclidean general relativity, and
where the constraints are imposed weakly. Its state space is a natural subspace
of the SO(4) spin-network space and matches the SO(3) hamiltonian spin network
space. The model provides a long sought SO(4)-covariant vertex amplitude for
loop quantum gravity.Comment: 6page
A influência da presença de ferro endógeno na remediação de diesel via reagente de Fenton modificado.
Este trabalho avaliou a eficiĂŞncia catalĂtica do ferro endĂłgeno na reação de Fenton para a remediação de diferentes solos tropicais contaminados com o Ăłleo diesel com diferentes teores das seguintes formas de ferro endĂłgenos: amorfo, pedogenĂ©tico, biodisponĂvel e total. Em 70% de degradação do Ăłleo diesel. ĂŤons fĂ©rricos encontrados, naturalmente, nos solos brasileiros tambĂ©m catalisam a decomposição do H2O2 para geração de radicais hidroxilas. Contudo, foi observado que a taxa de remediação Ă© dependente das formas de ferro encontradas nos solos
Avaliação do escurecimento de grãos de linhagens de feijoeiro-comum, no Estado de Mato Grosso.
O presente trabalho teve como objetivo avaliar linhagens de grĂŁo carioca com escurecimento lento de grĂŁos no estado de Mato Grosso.CONAF
Comparison of H/AL stoichiometry of mineral and organic soils in Brazil.
Exchangeable Al has been used as a criterion for the calculation of lime requirement in several Brazilian States. However, the laboratory method with extraction by a 1 mol L-1 KCl solution followed by indirect alkaline titration is not accurate for some Brazilian soils, mainly in the case of soils with high organic matter content. The objective of this study was therefore to evaluate the stoichiometry of H+/Al3+ in KCl soil extracts. The results suggested that organically complexed Al is the main contributor to exchangeable acidity in soils enriched with organic matter. Liming recommendations for organic soils based exclusively on exchangeable Al determined by the NaOH titration method should therefore be revised. A determinação de alumĂnio trocável Ă© utilizada como critĂ©rio para cálculo de calagem em vários estados brasileiros. Contudo, a determinação indireta pela titulação com NaOH, apĂłs extração com solução de KCl 1 mol L-1, pode nĂŁo ser adequada para certos tipos de solos brasileiros, notadamente aqueles que apresentem altos teores de carbono orgânico. Dessa forma, o principal objetivo deste trabalho foi avaliar a estequiometria da relação H+/Al3+ em extratos de KCl. Os resultados obtidos sugerem que o Al complexado pela matĂ©ria orgânica, em solos orgânicos, Ă© o principal contribuinte para a acidez trocável obtida por titulação. Dessa forma, a recomendação de calagem em solos orgânicos baseado somente na determinação de alumĂnio trocável por titulação com NaOH deve ser revista
Protective effects of phenolic constituents from Cytisus multiflorus, Lamium album L. and Thymus citriodorus on liver cells
The present study investigated the antioxidant and cytoprotective effects of purified ethanolic extracts of Cytisus multiflorus, Lamium album L. and Thymus citriodorus plants. These extracts showed high antioxidant activity in DPPH and reducing power assays. Using a model of chemical stress induced by potassium dichromate (DK) in human hepatoblastoma HepG2 cells, 50 ug/mL of C. multiflorus, L. album and T. citriodorus extracts decreased the rate of reactive oxygen species (ROS) production by 35%, 26% and 20%, respectively, when exposed to 25 mu M of DK. This effect was also observed for the treatment of cells with individual polyphenolic compounds determined in the extracts, or with mixtures prepared with individual polyphenolic compounds simulating the phenolic composition of the extracts. Additionally, the purified ethanolic extracts and the prepared polyphenolic mixtures showed a cytoprotective effect against DK-induced toxicity. The overall results emphasize the contribution of polyphenols in antioxidant and cytoprotective properties of the studied plants
Coherent states, constraint classes, and area operators in the new spin-foam models
Recently, two new spin-foam models have appeared in the literature, both
motivated by a desire to modify the Barrett-Crane model in such a way that the
imposition of certain second class constraints, called cross-simplicity
constraints, are weakened. We refer to these two models as the FKLS model, and
the flipped model. Both of these models are based on a reformulation of the
cross-simplicity constraints. This paper has two main parts. First, we clarify
the structure of the reformulated cross-simplicity constraints and the nature
of their quantum imposition in the new models. In particular we show that in
the FKLS model, quantum cross-simplicity implies no restriction on states. The
deeper reason for this is that, with the symplectic structure relevant for
FKLS, the reformulated cross-simplicity constraints, in a certain relevant
sense, are now \emph{first class}, and this causes the coherent state method of
imposing the constraints, key in the FKLS model, to fail to give any
restriction on states. Nevertheless, the cross-simplicity can still be seen as
implemented via suppression of intertwiner degrees of freedom in the dynamical
propagation. In the second part of the paper, we investigate area spectra in
the models. The results of these two investigations will highlight how, in the
flipped model, the Hilbert space of states, as well as the spectra of area
operators exactly match those of loop quantum gravity, whereas in the FKLS (and
Barrett-Crane) models, the boundary Hilbert spaces and area spectra are
different.Comment: 21 pages; statements about gamma limits made more precise, and minor
phrasing change
Serum 25-hydroxyvitamin D levels in patients with Granulomatosis with Polyangiitis: association with respiratory infection
OBJECTIVES: To determine the possible association of serum 25-hydroxyvitamin D (25OHD) levels with disease activity and respiratory infection in granulomatosis with polyangiitis patients during two different periods: winter/spring and summer/autumn. METHODS: Thirty-two granulomatosis with polyangiitis patients were evaluated in the winter/spring, and the same patients (except 5) were evaluated in summer/autumn (n=27). The 25OHD levels were measured by radioimmunoassay. Disease activity was assessed by the Birmingham Vasculitis Activity Score Modified for Wegener’s Granulomatosis (BVAS/WG) and antineutrophil cytoplasmic antibody (ANCA) positivity. Respiratory infection was defined according the Centers for Disease Control and Prevention criteria. RESULTS: 25OHD levels were lower among patients in winter/spring than in summer/autumn (32.31±13.10 vs. 38.98±10.97 ng/mL, p=0.04). Seven patients met the criteria for respiratory infection: 5 in winter/spring and 2 in summer/autumn. Patients with respiratory infection presented lower 25OHD levels than those without infection (25.15±11.70 vs. 36.73±12.08 ng/mL, p=0.02). A higher frequency of low vitamin D levels (25OH
Quality of Work Life: A Study on Civil Construction Workers
The civil construction sector has experienced ongoing changes due to the economic globalization, new technologies, and competition. It demands a large number of workers that are often recruited outside their original city, far from their families, with low work conditions, and without guarantee of continuity in employment, which may affect their health and performance. This study presents an exploratory and descriptive study with a quantitative approach, conducted by the Job Diagnostic Survey (JDS), with 159 workers in the civil construction sector in Brazil. The objective is to assess the level of satisfaction with work, compare the results of different workers at the workplace, and contribute to the discussion about QWL. It was found that the variable General Satisfaction with Work obtained the most negative general average score among the personal and the professional results, pointing out little satisfaction with their work as a whole, which can be improved through training and increase workers empowerment. This study carried out a survey with the construction worker, subjects who are hardly evaluated in research on working conditions. The JDS questionnaire was an important tool in this evaluation, contributing to understanding the variables that impact on the performance of these workers. In this context, improving the quality of work life (QWL) make it possible to assist managers to help workers’ satisfaction at work
- …