59,445 research outputs found

    Is 4U 0114+65 an eclipsing HMXB?

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    We present the pulsation and spectral characteristics of the HMXB 4U 0114+65 during a \emph{Suzaku} observation covering the part of the orbit that included the previously known low intensity emission of the source (dip) and the egress from this state. This dip has been interpreted in previous works as an X-ray eclipse. Notably, in this Suzaku observation, the count rate during and outside the dip vary by a factor of only 2-4 at odds with the eclipses of other HMXBs, where the intensity drops upto two orders of magnitude. The orbital intensity profile of 4U 0114+65 is characterized by a narrow dip in the RXTE-ASM (2-12 \rm{keV}) light curve and a shallower one in the Swift-BAT (15-50 \rm{keV}), which is different from eclipse ingress/egress behaviour of other HMXBs. The time-resolved spectral analysis reveal moderate absorption column density (NH_{H} - 2-20 ×\times 102210^{22} atoms cm2cm^{-2}) and a relatively low equivalent width (\sim 30 \rm{eV} \& 12 \rm{eV} of the iron Kα_\alpha and Kβ_\beta lines respectively) as opposed to the typical X-ray spectra of HMXBs during eclipse where the equivalent width is \sim 1 \rm{keV}. Both XIS and PIN data show clear pulsations during the dip, which we have further confirmed using the entire archival data of the IBIS/ISGRI and JEM-X instruments onboard \emph{INTEGRAL}. The results we presented question the previous interpretation of the dip in the light curve of 4U 0114+65 as an X-ray eclipse. We thus discuss alternative interpretations of the periodic dip in the light curve of 4U 0114+65.Comment: 16 pages, 7 figures, 1 table, Accepted in MNRA

    Inferential tests and modelling of functional trait convergence along environmental gradients

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    The motivation for this paper comes from a recent study which indicated that the influence of environmental filtering should increase with decreasing soil fertility, based on the premise that individuals will employ a resource-retentive strategy in a less productive ecosystem. Mean annual temperature (MAT) is one indicator of the productivity of the ecosystem. We aim to build a more accurate model of environmental filter and want to statistically test whether the environmental filter is stronger when the MAT is lower compared to when it is higher. Our findings throw an interesting insight into how the trait variability changes as a function of MAT and how it could be better modelled

    The study of excited oxygen molecule gas species production and quenching on thermal protection system materials

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    The detection of excited oxygen and ozone molecules formed by surface catalyzed oxygen atom recombination and reaction was investigated by laser induced fluorescence (LIF), molecular beam mass spectrometric (MBMS), and field ionization (FI) techniques. The experiment used partially dissociated oxygen flows from a microwave discharge at pressures in the range from 60 to 400 Pa or from an inductively coupled RF discharge at atmospheric pressure. The catalyst materials investigated were nickel and the reaction cured glass coating used for Space Shuttle reusable surface insulation tiles. Nonradiative loss processes for the laser excited states makes LIF detection of O2 difficult such that formation of excited oxygen molecules could not be detected in the flow from the microwave discharge or in the gaseous products of atom loss on nickel. MBMS experiments showed that ozone was a product of heterogeneous O atom loss on nickel and tile surfaces at low temperatures and that ozone is lost on these materials at elevated temperatures. FI was separately investigated as a method by which excited oxygen molecules may be conveniently detected. Partial O2 dissociation decreases the current produced by FI of the gas

    Assessment of the environmental toxicity and carcinogenicity of tungsten-based shot.

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    The toxicity of elemental tungsten released from discharged shot was assessed against previous studies that established a 1% toxic threshold for soil organisms. Extremely heavy theoretical shot loadings of 69,000 shot/ha were used to generate estimated environmental concentrations (EEC) for two brands of tungsten-based shot containing 51% and 95% tungsten. The corresponding tungsten EEC values were 6.5–13.5 mg W/kg soil, far below the 1% toxic threshold. The same shot loading in water produced tungsten EEC values of 2.1–4.4 mg W/L, levels that are not toxic under experimental conditions. Pure tungsten has not been shown to exhibit carcinogenic properties when ingested or embedded in animal tissues, but nickel, with which it is often alloyed, has known carcinogenicity. Given the large number of waterfowl that carry shot embedded in their body, it is advisable to screen lead shot substitutes for their carcinogenic potential through intra-muscular implantation

    The Microbiota and Health Promoting Characteristics of the Fermented Beverage Kefir

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    peer-reviewedKefir is a complex fermented dairy product created through the symbiotic fermentation of milk by lactic acid bacteria and yeasts contained within an exopolysaccharide and protein complex called a kefir grain. As with other fermented dairy products, kefir has been associated with a range of health benefits such as cholesterol metabolism and angiotensin-converting enzyme (ACE) inhibition, antimicrobial activity, tumor suppression, increased speed of wound healing, and modulation of the immune system including the alleviation of allergy and asthma. These reports have led to increased interest in kefir as a focus of research and as a potential probiotic-containing product. Here, we review those studies with a particular emphasis on the microbial composition and the health benefits of the product, as well as discussing the further development of kefir as an important probiotic product.The authors are funded through the Teagasc Walsh Fellowship Scheme(2014025)and internal Teagasc funding(RMIS6486). BW is supported by the Canada Research Chairs Program and research in the Cotter laboratory is funded by SFI through the PI award “Obesibiotics”(11/PI/1137)and in the form of a center grant (APC Microbiome Institute Grant Number SFI/12/RC/2273)

    Benzene formation in the inner regions of protostellar disks

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    Benzene (c-C6H6) formation in the inner 3 AU of a protostellar disk can be efficient, resulting in high abundances of benzene in the midplane region. The formation mechanism is different to that found in interstellar clouds and in protoplanetary nebulae, and proceeds mainly through the reaction between allene (C3H4) and its ion. This has implications for PAH formation, in that some fraction of PAHs seen in the solar system could be native rather than inherited from the interstellar medium.Comment: 9 pages, 2 colour figures, to be published in the Astrophysical Journal Letter

    Classification and analysis of emission-line galaxies using mean field independent component analysis

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    We present an analysis of the optical spectra of narrow emission-line galaxies, based on mean field independent component analysis (MFICA). Samples of galaxies were drawn from the Sloan Digital Sky Survey (SDSS) and used to generate compact sets of `continuum' and `emission-line' component spectra. These components can be linearly combined to reconstruct the observed spectra of a wider sample of galaxies. Only 10 components - five continuum and five emission line - are required to produce accurate reconstructions of essentially all narrow emission-line galaxies; the median absolute deviations of the reconstructed emission-line fluxes, given the signal-to-noise ratio (S/N) of the observed spectra, are 1.2-1.8 sigma for the strong lines. After applying the MFICA components to a large sample of SDSS galaxies we identify the regions of parameter space that correspond to pure star formation and pure active galactic nucleus (AGN) emission-line spectra, and produce high S/N reconstructions of these spectra. The physical properties of the pure star formation and pure AGN spectra are investigated by means of a series of photoionization models, exploiting the faint emission lines that can be measured in the reconstructions. We are able to recreate the emission line strengths of the most extreme AGN case by assuming the central engine illuminates a large number of individual clouds with radial distance and density distributions, f(r) ~ r^gamma and g(n) ~ n^beta, respectively. The best fit is obtained with gamma = -0.75 and beta = -1.4. From the reconstructed star formation spectra we are able to estimate the starburst ages. These preliminary investigations serve to demonstrate the success of the MFICA-based technique in identifying distinct emission sources, and its potential as a tool for the detailed analysis of the physical properties of galaxies in large-scale surveys.Comment: MNRAS accepted. 29 pages, 24 figures, 3 table
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