91 research outputs found

    The disk of the eruptive protostar V900 Mon; a MATISSE/VLTI and MUSE/VLT perspective

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    In this work, we study the silicate dust content in the disk of one of the youngest eruptive stars, V900 Mon, at the highest angular resolution probing down to the inner 10 au of said disk, and study the historical evolution of the system traced in part by a newly discovered emission clump. We performed high-angular resolution mid-infrared interferometric observations of V900 Mon with MATISSE/VLTI with a spatial coverage ranging from 38-m to 130-m baselines, and compared them to archival MIDI/VLTI data. We also mined and re-analyzed archival optical and infrared photometry of the star to study its long-term evolution since its eruption in the 1990s. We complemented our findings with integral field spectroscopy data from MUSE/VLT. The MATISSE/VLTI data suggest a radial variation of the silicate feature in the dusty disk, whereby at large spatial scales (≄10\geq10 au) the protostellar disk's emission is dominated by large-sized (≄1 Όm\geq1\,\mu m) silicate grains, while at smaller spatial scales and closer to the star (≀5\leq5 au), silicate emission is absent suggesting self-shielding. We propose that the self-shielding may be the result of small dust grains at the base of the collimated CO outflow previously detected by ALMA. A newly discovered knot in the MUSE/VLT data, located at a projected distance approximately 27,000 au from the star, is co-aligned with the molecular gas outflow at a P.A. of 250o250^o (±5o\pm5^o) consistent with the position angle and inclination of the disk. The knot is seen in emission in Hα\alpha, [N II], and the [S II] doublet and its kinematic age is about 5150 years. This ejected material could originate from a previous eruption.Comment: 18 pages, 16 figures, accepted for publication by Astronomy & Astrophysic

    Legacy effects override soil properties for CO 2 and N 2 O but not CH 4 emissions following digestate application to soil

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    The application of organic materials to soil can recycle nutrients and increase organic matter in agricultural lands. Digestate can be used as a nutrient source for crop production but it has also been shown to stimulate greenhouse gas (GHG) emissions from amended soils. While edaphic factors, such as soil texture and pH, have been shown to be strong determinants of soil GHG fluxes, the impact of the legacy of previous management practices is less well understood. Here we aim to investigate the impact of such legacy effects and to contrast them against soil properties to identify the key determinants of soil GHG fluxes following digestate application. Soil from an already established field experiment was used to set up a pot experiment, to evaluate N2O, CH4 and CO2 fluxes from cattle‐slurry‐digestate amended soils. The soil had been treated with farmyard manure, green manure or synthetic N‐fertilizer, 18 months before the pot experiment was set up. Following homogenization and a preincubation stage, digestate was added at a concentration of 250 kg total N/ha eq. Soil GHG fluxes were then sampled over a 64 day period. The digestate stimulated emissions of the three GHGs compared to controls. The legacy of previous soil management was found to be a key determinant of CO2 and N2O flux while edaphic variables did not have a significant effect across the range of variables included in this experiment. Conversely, edaphic variables, in particular texture, were the main determinant of CH4 flux from soil following digestate application. Results demonstrate that edaphic factors and current soil management regime alone are not effective predictors of soil GHG flux response following digestate application. Knowledge of the site management in terms of organic amendments is required to make robust predictions of the likely soil GHG flux response following digestate application to soil

    Short RNAs Are Transcribed from Repressed Polycomb Target Genes and Interact with Polycomb Repressive Complex-2

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    Polycomb proteins maintain cell identity by repressing the expression of developmental regulators specific for other cell types. Polycomb repressive complex-2 (PRC2) catalyzes trimethylation of histone H3 lysine-27 (H3K27me3). Although repressed, PRC2 targets are generally associated with the transcriptional initiation marker H3K4me3, but the significance of this remains unclear. Here, we identify a class of short RNAs, ~50–200 nucleotides in length, transcribed from the 5â€Č end of polycomb target genes in primary T cells and embryonic stem cells. Short RNA transcription is associated with RNA polymerase II and H3K4me3, occurs in the absence of mRNA transcription, and is independent of polycomb activity. Short RNAs form stem-loop structures resembling PRC2 binding sites in Xist, interact with PRC2 through SUZ12, cause gene repression in cis, and are depleted from polycomb target genes activated during cell differentiation. We propose that short RNAs play a role in the association of PRC2 with its target genes.National Institutes of Health (U.S.) (Grant HG002668)National Institutes of Health (U.S.) (Grant NS055923

    PI3K(p110 alpha) Protects Against Myocardial Infarction-Induced Heart Failure Identification of PI3K-Regulated miRNA and mRNA

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    Objective: Myocardial infarction (MI) is a serious complication of atherosclerosis associated with increasing mortality attributable to heart failure. Activation of phosphoinositide 3-kinase [PI3K(p110α)] is considered a new strategy for the treatment o

    The mineral composition and spatial distribution of the dust ejecta of NGC 6302

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    We have analysed the full ISO spectrum of the planetary nebula NGC 6302 in order to derive the mineralogical composition of the dust in the nebula. We use an optically thin dust model in combination with laboratory measurements of cosmic dust analogues. We find two main temperature components at about 100 and 50 K respectively, with distinctly different dust compositions. The warm component contains an important contribution from dust without strong infrared resonances. In particular the presence of small warm amorphous silicate grains can be excluded. The detection of weak PAH bands also points to a peculiar chemical composition of the dust in this oxygen-rich nebula. The cool dust component contains the bulk of the mass and shows strong emission from crystalline silicates, which contain about 10 percent of the mass. In addition, we identify the 92 micron band with the mineral calcite, and argue that the 60 micron band contains a contribution from the carbonate dolomite. We present the mass absorption coefficients of six different carbonate minerals. The geometry of the dust shell around NGC 6302 is studied with mid-infrared images obtained with TIMMI2. We argue that the cool dust component is present in a circumstellar dust torus, while the diffuse emission from the warm component originates from the lobes.Comment: 13 pages, 10 figures, accepted for publication in A&

    Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets

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    We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1 micrometer Hubble Space Telescope/NICMOS data. While submillimeter studies suggested there is a dust-depleted cavity with r = 0".35, we find scattered light as close as 0".1 (20-28 AU) from the star, with no visible cavity at H, K', or Ks . We find two small-scaled spiral structures that asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h approximately 0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5(exp +3)(sub -4) M(sub J), in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L' and angular differential imaging with Locally Optimized Combination of Images at K' and Ks , we exclude stellar or massive brown dwarf companions within 300 mas of the Herbig Ae star, and all but planetary mass companions exterior to 0".5. We reach 5 sigma contrasts limiting companions to planetary masses, 3-4 M(sub J) at 1".0 and 2 M(sub J) at 1".55, using the COND models. Collectively, these data strengthen the case for MWC 758 already being a young planetary system

    Methods of identifying and recruiting older people at risk of social isolation and loneliness: A mixed methods review

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    BackgroundLoneliness and social isolation are major determinants of mental wellbeing, especially among older adults. The effectiveness of interventions to address loneliness and social isolation among older adults has been questioned due to the lack of transparency in identifying and recruiting populations at risk. This paper aims to systematically review methods used to identify and recruit older people at risk of loneliness and social isolation into research studies that seek to address loneliness and social isolation.MethodsIn total, 751 studies were identified from a structured search of eleven electronic databases combined with hand searching of reference bibliography from identified studies for grey literature. Studies conducted between January 1995 and December 2017 were eligible provided they recruited community living individuals aged 50 and above at risk of social isolation or loneliness into an intervention study.ResultA total of 22 studies were deemed eligible for inclusion. Findings from these studies showed that the most common strategy for inviting people to participate in intervention studies were public-facing methods including mass media and local newspaper advertisements. The majority of participants identified this way were self-referred, and in many cases self-identified as lonely. In most cases, there was no standardised tool for defining loneliness or social isolation. However, studies that recruited via referral by recognised agencies reported higher rates of eligibility and enrolment. Referrals from primary care were only used in a few studies. Studies that included agency referral either alone or in combination with multiple forms of recruitment showed more promising recruitment rates than those that relied on only public facing methods. Further research is needed to establish the cost-effectiveness of multiple forms of referral.ConclusionFindings from this study demonstrate the need for transparency in writing up the methods used to approach, assess and enrol older adults at risk of becoming socially isolated. None of the intervention studies included in this review justified their recruitment strategies. The ability of researchers to share best practice relies greatly on the transparency of research

    Effects of Insulin Detemir and NPH Insulin on Body Weight and Appetite-Regulating Brain Regions in Human Type 1 Diabetes: A Randomized Controlled Trial

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    Studies in rodents have demonstrated that insulin in the central nervous system induces satiety. In humans, these effects are less well established. Insulin detemir is a basal insulin analog that causes less weight gain than other basal insulin formulations, including the current standard intermediate-long acting Neutral Protamine Hagedorn (NPH) insulin. Due to its structural modifications, which render the molecule more lipophilic, it was proposed that insulin detemir enters the brain more readily than other insulins. The aim of this study was to investigate whether insulin detemir treatment differentially modifies brain activation in response to food stimuli as compared to NPH insulin. In addition, cerebral spinal fluid (CSF) insulin levels were measured after both treatments. Brain responses to viewing food and non-food pictures were measured using functional Magnetic Resonance Imaging in 32 type 1 diabetic patients, after each of two 12-week treatment periods with insulin detemir and NPH insulin, respectively, both combined with prandial insulin aspart. CSF insulin levels were determined in a subgroup. Insulin detemir decreased body weight by 0.8 kg and NPH insulin increased weight by 0.5 kg (p = 0.02 for difference), while both treatments resulted in similar glycemic control. After treatment with insulin detemir, as compared to NPH insulin, brain activation was significantly lower in bilateral insula in response to visual food stimuli, compared to NPH (p = 0.02 for right and p = 0.05 for left insula). Also, CSF insulin levels were higher compared to those with NPH insulin treatment (p = 0.003). Our findings support the hypothesis that in type 1 diabetic patients, the weight sparing effect of insulin detemir may be mediated by its enhanced action on the central nervous system, resulting in blunted activation in bilateral insula, an appetite-regulating brain region, in response to food stimuli.ClinicalTrials.gov NCT00626080
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