2,619 research outputs found
Twenty-one centimeter tomography with foregrounds
Twenty-one centimeter tomography is emerging as a powerful tool to explore
the end of the cosmic dark ages and the reionization epoch, but it will only be
as good as our ability to accurately model and remove astrophysical foreground
contamination. Previous treatments of this problem have focused on the angular
structure of the signal and foregrounds and what can be achieved with limited
spectral resolution (bandwidths in the 1 MHz range). In this paper we introduce
and evaluate a ``blind'' method to extract the multifrequency 21cm signal by
taking advantage of the smooth frequency structure of the Galactic and
extragalactic foregrounds. We find that 21 cm tomography is typically limited
by foregrounds on scales Mpc and limited by noise on scales Mpc, provided that the experimental bandwidth can be made substantially
smaller than 0.1 MHz. Our results show that this approach is quite promising
even for scenarios with rather extreme contamination from point sources and
diffuse Galactic emission, which bodes well for upcoming experiments such as
LOFAR, MWA, PAST, and SKA.Comment: 10 pages, 6 figures. Revised version including various cases with
high noise level. Major conclusions unchanged. Accepted for publication in
Ap
Detection of azo dyes using carbon dots from olive mill wastes
Azo dyes are widely spread in our day life, being heavily used in cosmetics, healthcare products, textile industries, and as artificial food colorants. This intense industrial activity, which inherently includes their own production, inexorably leads to uncontrolled release of dyes into the environment. As emerging pollutants, their detection, particularly in water systems, is a priority. Herein, a fluorescence-based method was employed for the sensitive and selective detection of anionic and neutral azo dyes. Carbon dots (CDs) synthesized from wet pomace (WP), an abundant semi-solid waste of olive mills, were used as probes. An outstanding capability for detection of azo dyes methyl orange (MO) and methyl red (MR) in aqueous solutions was disclosed, which reached a limit of detection (LOD) of 151 ppb for MO. The selectivity of WP-CDs for the anionic azo dye (MO) was established through competitive experiments with other dyes, either anionic (indigo carmine) or cationic (fuchsin, methylene blue, and rhodamine 6G); perchlorate salts of transition metal cations (Cu(II), Co(II), Fe(II), Fe(III), Hg(II), and Pb(II)); and sodium salts of common anions (NO3-, CO32-, Cl-, and SO42-). Evidence has been collected that supports static quenching as the main transduction event underlying the observed quenching of the probe's fluorescence, combined with a dynamic resonance energy transfer (RET) mechanism at high MO concentrations.info:eu-repo/semantics/publishedVersio
Aspectos epistemolĂłgicos y praxiolĂłgicos de un libro de texto de biologĂa para secundaria desde la perspectiva de la "Ciencia Escolar"
The morita-baylis-hillman reaction: advances and contributions from brazilian chemistry
The Morita-Baylis-Hillman reaction is an organocatalyzed chemical transformation that allows access to small poly-functionalized molecules and has considerable synthetic potential and promising biological profiles. In this review, we report the efforts made by Brazilian research groups in recent years on the development of Morita-Baylis-Hillman chemistry. The review covers these contributions, with a focus on mechanistic studies, improvement of the experimental conditions, and the use of Morita-Baylis-Hillman adducts as building blocks for the synthesis of heterocycles, natural products and drugs126830852CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPsem informação2013/10449-5; 2013/07600-5; 2012/08048-
Small-scale CMB Temperature and Polarization Anisotropies due to Patchy Reionization
We study contributions from inhomogeneous (patchy) reionization to arcminute
scale () cosmic microwave background (CMB) anisotropies.
We show that inhomogeneities in the ionization fraction, rather than in the
mean density, dominate both the temperature and the polarization power spectra.
Depending on the ionization history and the clustering bias of the ionizing
sources, we find that rms temperature fluctuations range from 2 K to 8
K and the corresponding values for polarization are over two orders of
magnitude smaller. Reionization can significantly bias cosmological parameter
estimates and degrade gravitational lensing potential reconstruction from
temperature maps but not from polarization maps. We demonstrate that a simple
modeling of the reionization temperature power spectrum may be sufficient to
remove the parameter bias. The high- temperature power spectrum will
contain some limited information about the sources of reionization.Comment: 11 pages, 8 figures. Minor changes to match version accepted by Ap
Prognostic Importance of Dyspnea for Cardiovascular Outcomes and Mortality in Persons without Prevalent Cardiopulmonary Disease: The Atherosclerosis Risk in Communities Study
The relationship between dyspnea and incident heart failure (HF) and myocardial infarction (MI) among patients without previously diagnosed cardiopulmonary disease is unclear. We studied the prognostic relevance of self-reported dyspnea for cardiovascular outcomes and all-cause mortality in persons without previously diagnosed cardiopulmonary disease
Effect of gastrointestinal digestion on the bioaccessibility of phenolic compounds and antioxidant activity of fermented Aloe vera juices
Plant-based beverages are enriched by the fermentation process. However, their biocompounds are transformed during gastrointestinal digestion, improving their bioaccessibility, which is of primary importance when considering the associated health benefits. This study aimed to evaluate the effect of in vitro gastrointestinal digestion on phenolic compound bioaccessibility and antioxidant activity of novel Aloe vera juices fermented by probiotic Enterococcus faecium and Lactococcus lactis. Aloe vera juices were digested using the standardized static INFOGEST protocol. During digestion, phenolic compounds and antioxidant activity (DPPH, ABTS, and FRAP) were accessed. The digestion process was seen to significantly increase the total phenolic content of the fermented Aloe vera juices. The fermentation of Aloe vera increased the bioaccessibility of juice biocompounds, particularly for kaempferol, ellagic acid, resveratrol, hesperidin, ferulic acid, and aloin. The phenolics released during digestion were able to reduce the oxidative radicals assessed by ABTS and FRAP tests, increasing the antioxidant action in the intestine, where they are absorbed. The fermentation of Aloe vera by probiotics is an excellent process to increase the bioavailability of beverages, resulting in natural added-value functional products.This work was supported by the National Council of Science and Technology (CONACYT, Mexico) with financial support (CVU 559365). This study was also supported by the Portuguese Foundation for Science and Technology under the scope of the strategic funding of UIDB/04469/2020 unit and by LABBELSâAssociate Laboratory in Biotechnology, Bioengineering, and Microelectromechanical Systems, LA/P/0029/2020. It was also supported by the European Regional Development Fund (ERDF) through the Competitiveness Factors Operational ProgramâNorte 2020, COMPETE, and by National Funds through the FCTâunder the project AgriFood XXI (NORTE-01-0145-FEDER-000041). Clarisse Nobre acknowledges FCT for the assistant research contract 2021.01234.CEECINDinfo:eu-repo/semantics/publishedVersio
Effect of an extract of Centella asiatica on the biodistribution of sodium pertechnetate (Na<sup>99m</sup>TcO<sub>4</sub>) and on the fixation of radioactivity on blood constituents
This study evaluates the effects of an acute treatment with a Centella asiatica (CA) extract on the biodistribution of the radiopharmaceutical Na99mTcO4 and on the fixation of technetium-99m on blood constituents. Wistar rats were treated with CA extract and, 1 hour after, Na99mTcO4 was administered; organs/tissues were withdrawn and weighted. The radioactivity was counted to calculate the percentage of activity per gram (%ATI/g). Also, blood samples were withdrawn, plasma (P), blood cells (BC), insoluble fraction (IF) and soluble fractions of P and BC were isolated and the radioactivity was counted to calculate the percentage of activity (%ATI). Data indicated that the acute treatment with CA extract changed significantly (p99mTcO4 and the fixation of the technetium-99m on blood constituents in an acute treatment
Multifrequency analysis of 21 cm fluctuations from the Era of Reionization
We study the prospects for extracting detailed statistical properties of the
neutral Hydrogen distribution during the era of reionization using the
brightness temperature fluctuations from redshifted 21 cm line emission.
Detection of this signal is complicated by contamination from foreground
sources such as diffuse Galactic synchrotron and free-free emission at low
radio frequencies, extragalactic free-free emission from ionized regions and
radio point sources. We model these foregrounds to determine the extent to
which 21 cm fluctuations can be detected with upcoming experiments. We find
that not only the level of correlation from one frequency to another, but also
the functional form of the foreground correlations has a substantial impact on
foreground removal. We calculate how well the angular power spectra of the 21cm
fluctuations can be determined. We also show that the large-scale bias of the
neutral Hydrogen gas distribution with respect to the density field, can be
determined with high precision and used to distinguish between different
reionization histories.Comment: 14 pages, 14 figures. New version to match paper accepted for
publication in ApJ. The frequency cross-correlations of the signal are now
smaller. Main conclusions of the paper remain unchange
Antibodies directed to antigens secreted by murine epithelioid macrophages modulate BCG-induced granulomata
The authors have previously shown that epithelioid cells isolated from mice secrete a factor, called macrophage deactivating factor (MDF), that promptly deactivates superoxide release by activated macrophages and neutrophils. In this paper some biological properties of a polyclonal rat antiserum directed to MDF and other substances secreted by these cells are described. The immunoglobulin fraction of this antiserum reacted, by immunocytochemical methods, with epitopes in the cell membrane of macrophages adherent to coverslips subcutaneously implanted for 14 days; but not for 5 days. It also reacted with antigens within and outside cells in BCG-induced granulomas. This antiserum blocked completely the macrophage deactivating activity of epithelioid cell culture supernatants. Anti-IL-10 monoclonal antibody, did not block MDF activity. The administration of the immunoglobulin fraction from immunized rats to C5 deficient mice bearing BCG-induced granulomatas in the footpad, significantly reduced the size of the lesions. A marked necrosis of inflammatory cells and mononuclear cells phagocyting debris of necrotic cells were observed in these lesions
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