8,752 research outputs found

    CO observations and investigation of triggered star formation towards N10 infrared bubble and surroundings

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    We studied the environment of the dust bubble N10 in molecular emission. Infrared bubbles, first detected by the GLIMPSE survey at 8.0 μ\mum, are ideal regions to investigate the effect of the expansion of the HII region on its surroundings eventual triggered star formation at its borders. In this work, we present a multi-wavelength study of N10. This bubble is especially interesting as infrared studies of the young stellar content suggest a scenario of ongoing star formation, possibly triggered, on the edge of the HII region. We carried out observations of 12^{12}CO(1-0) and 13^{13}CO(1-0) emission at PMO 13.7-m towards N10. We also analyzed the IR and sub-mm emission on this region and compare those different tracers to obtain a detailed view of the interaction between the expanding HII region and the molecular gas. We also estimated the parameters of the denser cold dust condensation and of the ionized gas inside the shell. Bright CO emission was detected and two molecular clumps were identified, from which we have derived physical parameters. We also estimate the parameters for the densest cold dust condensation and for the ionized gas inside the shell. The comparison between the dynamical age of this region and the fragmentation time scale favors the "Radiation-Driven Implosion" mechanism of star formation. N10 reveals to be specially interesting case with gas structures in a narrow frontier between HII region and surrounding molecular material, and with a range of ages of YSOs situated in region indicating triggered star formation.Comment: Version 2 - Submmited to ApJ (under review

    On the Estimation of the Surface Elevation of Regular and Irregular Waves Using the Velocity Field of Bubbles

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    This paper describes a new set of experiments focused on estimating time series of the free surface elevation of water (FSEW) from velocities recorded by submerged air bubbles under regular and irregular waves using a low-cost non-intrusive technique. The main purpose is to compute wave heights and periods using time series of velocities recorded at any depth. The velocities were taken from the tracking of a bubble curtain with only one high-speed digital video camera and a bubble generator. These experiments eliminate the need of intrusive instruments while the methodology can also be applied if the free surface is not visible or even if only part of the depth can be recorded. The estimation of the FSEW was successful for regular waves and reasonably accurate for irregular waves. Moreover, the algorithm to reconstruct the FSEW showed better results for larger wave amplitudes

    Molecules with a peptide link in protostellar shocks: a comprehensive study of L1157

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    Interstellar molecules with a peptide link -NH-C(=O)-, like formamide (NH2_2CHO), acetamide (NH2_2COCH3_3) and isocyanic acid (HNCO) are particularly interesting for their potential role in pre-biotic chemistry. We have studied their emission in the protostellar shock regions L1157-B1 and L1157-B2, with the IRAM 30m telescope, as part of the ASAI Large Program. Analysis of the line profiles shows that the emission arises from the outflow cavities associated with B1 and B2. Molecular abundance of ≈ (0.4−1.1)×10−8\approx~(0.4-1.1)\times 10^{-8} and (3.3−8.8)×10−8(3.3-8.8)\times 10^{-8} are derived for formamide and isocyanic acid, respectively, from a simple rotational diagram analysis. Conversely, NH2_2COCH3_3 was not detected down to a relative abundance of a few ≤10−10\leq 10^{-10}. B1 and B2 appear to be among the richest Galactic sources of HNCO and NH2_2CHO molecules. A tight linear correlation between their abundances is observed, suggesting that the two species are chemically related. Comparison with astrochemical models favours molecule formation on ice grain mantles, with NH2_2CHO generated from hydrogenation of HNCO.Comment: 11 pages, 9 figures. Accepted for publication in MNRAS Main Journal. Accepted 2014 August 19, in original form 2014 July

    Control of Glycolytic Flux by AMPK and p53-mediated Signaling Pathways in Tumor Cells Grown at Low pH

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    Introduction: Tumor cells grow in nutrient and oxygen deprived microenvironments and adapt to the suboptimal growth conditions by altering metabolic pathways. This adaptation process characteristically results in a tumor phenotype that displays upregulated Hif-1α anaerobic glycolysis, chronic acidification, reduced rate of overall protein synthesis, lower rate of cell proliferation and aggressive invasive characteristics. Most transplantable tumors exhibit a pHe of 6.7- 7.0; the DB-1 melanoma xenografts used here have a pHe=6.7. Understanding tumor cell reaction to the microenvironment is a critical factor in predicting the tumor response to radiotherapy. The glucose regulatory molecule, 6-Phosphofructo-2-Kinase/Fructose-2,6- Biphosphatase Isoform-3 (PFKFB3), is a bifunctional enzyme central to glycolytic flux and downstream of the metabolic stress sensor AMP-activated protein kinase (AMPK), which we show activates an isoform of phosphofructokinase (PFK-2). Radiation Research Society (RRS) 8th Annual Meeting September 25-29, Maui, H

    Control of Glycolytic Flux by AMPK and p53-Mediated Signaling Pathways in Tumor Cells Adapted to Grow at Low pH

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    Introduction: Tumor cells grow in nutrient and oxygen deprived microenvironments and adapt to the suboptimal growth conditions by altering metabolic pathways. This adaptation process characteristically results in a tumor phenotype that displays anaerobic glycolysis, chronic acidification and aggressive tumor characteristics. Understanding the tumor cell reaction to the microenvironment is a critical factor in predicting the tumor response to hyperthermia. The glucose regulatory molecule, 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase Isoform-3 (PFKFB3), is a bifunctional enzyme central to glycolytic flux and downstream of the metabolic stress sensor AMP-activated protein kinase (AMPK), which has been shown to activate an isoform of Phosphofructokinase (PFK-2). Society for Thermal Medicine Annual Meeting April 23-26, Clearwater Beach, FL

    Search for the Higgs Boson H20H_2^0 at LHC in 3-3-1 Model

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    We present an analysis of production and signature of neutral Higgs boson (H20H_{2}^{0}) on the version of the 3-3-1 model containing heavy leptons at the Large Hadron Collider. We studied the possibility to identify it using the respective branching ratios. Cross section are given for the collider energy, s=\sqrt{s} = 14 TeV. Event rates and significances are discussed for two possible values of integrated luminosity, 300 fb−1^{-1} and 3000 fb−1^{-1}.Comment: 17 pages 7 figures. arXiv admin note: substantial text overlap with arXiv:1205.404

    Beyond mean-field bistability in driven-dissipative lattices: bunching-antibunching transition and quantum simulation

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    In the present work we investigate the existence of multiple nonequilibrium steady states in a coherently driven XY lattice of dissipative two-level systems. A commonly used mean-field ansatz, in which spatial correlations are neglected, predicts a bistable behavior with a sharp shift between low- and high-density states. In contrast one-dimensional matrix product methods reveal these effects to be artifacts of the mean-field approach, with both disappearing once correlations are taken fully into account. Instead, a bunching-antibunching transition emerges. This indicates that alternative approaches should be considered for higher spatial dimensions, where classical simulations are currently infeasible. Thus we propose a circuit QED quantum simulator implementable with current technology to enable an experimental investigation of the model considered
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