154 research outputs found
Experimental and Simulation Study of Adsorption in Postcombustion Conditions Using a Microporous Biochar. 1. CO2 and N2 Adsorption
The influence of N2 on CO2 adsorption was evaluated using a microporous biochar with a narrow pore size distribution. The adsorption isotherms of pure CO2 and N2 were measured at 0, 30, 50, and 70 °C up to 120 kPa and fitted to the Toth adsorption model. Dynamic breakthrough experiments were carried out in a fixed-bed adsorption unit using binary mixtures with compositions representative of different postcombustion streams (8â30% CO2) from ambient temperature to 70 °C. Dynamic adsorption experiments were simulated to validate the mathematical model of the adsorption process, as a necessary step for its later use for process design. The Ideal Adsorption Solution (IAS) theory, based on the pure component adsorption models, was used to account for competitive adsorption with satisfactory results. The information gathered in the present work will be used to extend the validity of the model to the adsorption of postcombustion streams containing H2O in part 2.Work was carried out with financial support from the HiPerCap
Project of the European Union 7th Framework Programme
FP7 (2007-2013; Grant Agreement number: 60855). M.G.P.
acknowledges funding from the CSIC (JAE-Doc program
cofinanced by the European Social Fund). N.Q. acknowledges
funding from the Government of the Principado de Asturias
(Severo Ochoa Program). The authors also appreciate the
support from the technical consultants of AspenTechnology
Inc., M.M. and E.L.Peer reviewe
PHANGS CO kinematics: disk orientations and rotation curves at 150 pc resolution
We present kinematic orientations and high resolution (150 pc) rotation
curves for 67 main sequence star-forming galaxies surveyed in CO (2-1) emission
by PHANGS-ALMA. Our measurements are based on the application of a new fitting
method tailored to CO velocity fields. Our approach identifies an optimal
global orientation as a way to reduce the impact of non-axisymmetric (bar and
spiral) features and the uneven spatial sampling characteristic of CO emission
in the inner regions of nearby galaxies. The method performs especially well
when applied to the large number of independent lines-of-sight contained in the
PHANGS CO velocity fields mapped at 1'' resolution. The high resolution
rotation curves fitted to these data are sensitive probes of mass distribution
in the inner regions of these galaxies. We use the inner slope as well as the
amplitude of our fitted rotation curves to demonstrate that CO is a reliable
global dynamical mass tracer. From the consistency between photometric
orientations from the literature and kinematic orientations determined with our
method, we infer that the shapes of stellar disks in the mass range of log()=9.0-10.9 probed by our sample are very close to circular
and have uniform thickness.Comment: 19 figures, 36 pages, accepted for publication in ApJ. Table of
PHANGS rotation curves available from http://phangs.org/dat
ALMA resolves giant molecular clouds in a tidal dwarf galaxy
Tidal dwarf galaxies (TDGs) are gravitationally bound condensations of gas and stars that formed during galaxy interactions. Here we
present multi-configuration ALMA observations of J1023+1952, a TDG in the interacting system Arp 94, where we resolved CO(2â1)
emission down to giant molecular clouds (GMCs) at 0.6400 ⌠45 pc resolution. We find a remarkably high fraction of extended molecular emission (âŒ80â90%), which is filtered out by the interferometer and likely traces diffuse gas. We detect 111 GMCs that give a similar mass spectrum as those in the Milky Way and other nearby galaxies (a truncated power law with a slope of â1.76±0.13). We also
study Larsonâs laws over the available dynamic range of GMC properties (âŒ2 dex in mass and âŒ1 dex in size): GMCs follow the sizemass relation of the Milky Way, but their velocity dispersion is higher such that the size-linewidth and virial relations appear superlinear, deviating from the canonical values. The global molecular-to-atomic gas ratio is very high (âŒ1) while the CO(2â1)/CO(1â0)
ratio is quite low (âŒ0.5), and both quantities vary from north to south. Star formation predominantly takes place in the south of the
TDG, where we observe projected offsets between GMCs and young stellar clusters ranging from âŒ50 pc to âŒ200 pc; the largest
offsets correspond to the oldest knots, as seen in other galaxies. In the quiescent north, we find more molecular clouds and a higher
molecular-to-atomic gas ratio (âŒ1.5); atomic and diffuse molecular gas also have a higher velocity dispersion there. Overall, the organisation of the molecular interstellar medium in this TDG is quite different from other types of galaxies on large scales, but the
properties of GMCs seem fairly similar, pointing to near universality of the star-formation process on small scales.Instituto de Salud Carlos III
Spanish Government
PID2019-106027GA-C44Spanish Ministerio de Economia y Competitividad
AYA2017-84897-PEuropean CommissionJunta de Andalucia
European Commission
FQM108European Research Council (ERC)
726384/EMPIRE
714907MCIU/AEI/FEDER,UE
PGC2018-094671-B-I00
AYA2016-76682-C3-2-PGerman Research Foundation (DFG)
KR4801/1-1German Research Foundation (DFG)
KR4801/2-
Cloud-Scale Molecular Gas Properties in 15 Nearby Galaxies
We measure the velocity dispersion, , and surface density, ,
of the molecular gas in nearby galaxies from CO spectral line cubes with
spatial resolution - pc, matched to the size of individual giant
molecular clouds. Combining galaxies from the PHANGS-ALMA survey with
targets from the literature, we characterize independent
sightlines where CO is detected at good significance. and
show a strong positive correlation, with the best-fit power law slope close to
the expected value for resolved, self-gravitating clouds. This indicates only
weak variation in the virial parameter
, which is - for
most galaxies. We do, however, observe enormous variation in the internal
turbulent pressure , which spans
across our sample. We find , , and
to be systematically larger in more massive galaxies. The
same quantities appear enhanced in the central kpc of strongly barred galaxies
relative to their disks. Based on sensitive maps of M31 and M33, the slope of
the - relation flattens at
, leading to high for a given
and high apparent . This echoes results found in
the Milky Way, and likely originates from a combination of lower beam filling
factors and a stronger influence of local environment on the dynamical state of
molecular gas in the low density regime.Comment: Accepted for publication in ApJ. 45 pages, 11 figures, 8 tables, 4
Appendices; key results summarized in Figure 10. Machine-readable table can
be downloaded at http://www.astronomy.ohio-state.edu/~sun.1608/datafile3.txt
prior to publication. For a brief video describing the main results of this
paper, please see https://www.youtube.com/watch?v=-_eL7t1PVq8&
The headlight cloud in NGC 628: An extreme giant molecular cloud in a typical galaxy disk
Context. Cloud-scale surveys of molecular gas reveal the link between giant molecular cloud properties and star formation across a range of galactic environments. Cloud populations in galaxy disks are considered to be representative of the normal star formation process, while galaxy centers tend to harbor denser gas that exhibits more extreme star formation. At high resolution, however, molecular clouds with exceptional gas properties and star formation activity may also be observed in normal disk environments. In this paper we study the brightest cloud traced in CO(2-1) emission in the disk of nearby spiral galaxy NGC 628. Aims. We characterize the properties of the molecular and ionized gas that is spatially coincident with an extremely bright H ii region in the context of the NGC 628 galactic environment. We investigate how feedback and large-scale processes influence the properties of the molecular gas in this region.
Methods. High-resolution ALMA observations of CO(2-1) and CO(1â0) emission were used to characterize the mass and dynamical state of the 'headlight' molecular cloud. The characteristics of this cloud are compared to the typical properties of molecular clouds in NGC 628. A simple large velocity gradient (LVG) analysis incorporating additional ALMA observations of 13CO(1â0), HCO+(1â0), and HCN(1â0) emission was used to constrain the beam-diluted density and temperature of the molecular gas. We analyzed the MUSE spectrum using Starburst99 to characterize the young stellar population associated with the H ii region.
Results. The unusually bright headlight cloud is massive (1â2 x 107 M), with a beam-diluted density of nH2 = 5 x 104
cmâ3 based on LVG modeling. It has a low virial parameter, suggesting that the CO emission associated with this cloud may be overluminous due to heating by the H ii region. A young (2â4 Myr) stellar population with mass 3 x105 M is associated.
Conclusions. We argue that the headlight cloud is currently being destroyed by feedback from young massive stars. Due to the large mass of the cloud, this phase of the its evolution is long enough for the impact of feedback on the excitation of the gas to be observed. The high mass of the headlight cloud may be related to its location at a spiral co-rotation radius, where gas experiences reduced galactic shear compared to other regions of the disk and receives a sustained inflow of gas that can promote the mass growth of the cloud.CNH, AH and JP acknowledge support from the Programme National âPhysique et Chimie du Milieu Interstellaireâ (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES, and
from the Programme National Cosmology and Galaxies (PNCG) of CNRS/INSU
with INP and IN2P3, co-funded by CEA and CNES. AU acknowledges support from the Spanish funding grants AYA2016-79006-P (MINECO/FEDER)
and PGC2018-094671-B-I00 (MCIU/AEI/FEDER). The work of AKL, JS, and
DU is partially supported by the National Science Foundation under Grants No.
1615105, 1615109, and 1653300. FB acknowledges funding from the European
Unionâs Horizon 2020 research and innovation programme (grant agreement No
726384). APSH is a fellow of the International Max Planck Research School
for Astronomy and Cosmic Physics at the University of Heidelberg (IMPRSHD). SCOG acknowledges support from the DFG via SFB 881 âThe Milky Way
Systemâ (sub-projects B1, B2 and B8). JMDK gratefully acknowledges funding from the European Research Council (ERC) under the European Unionâs Horizon 2020 research and innovation programme via the ERC Starting Grant MUSTANG (grant agreement number 714907). JMDK and MC gratefully acknowledge funding from the German Research Foundation (DFG) in the form of an
Emmy Noether Research Group (grant number KR4801/1-1). SEM acknowledges funding during part of this work from the Deutsche Forschungsgemeinschaft (DFG) via grant SCHI 536/7-2 as part of the priority program SPP 1573
âISM-SPP: Physics of the Interstellar Mediumâ
Stellar populations of bulges at low redshift
This chapter summarizes our current understanding of the stellar population
properties of bulges and outlines important future research directions.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen
E., Peletier R., Gadotti D., Springer Publishing. 34 pages, 12 figure
The lifecycle of molecular clouds in nearby star-forming disc galaxies
It remains a major challenge to derive a theory of cloud-scale (â âČ100âpc) star formation and feedback, describing how galaxies convert gas into stars as a function of the galactic environment. Progress has been hampered by a lack of robust empirical constraints on the giant molecular cloud (GMC) lifecycle. We address this problem by systematically applying a new statistical method for measuring the evolutionary timeline of the GMC lifecycle, star formation, and feedback to a sample of nine nearby disc galaxies, observed as part of the PHANGS-ALMA survey. We measure the spatially resolved (âŒ100âpc) CO-to-Hâα flux ratio and find a universal de-correlation between molecular gas and young stars on GMC scales, allowing us to quantify the underlying evolutionary timeline. GMC lifetimes are short, typically 10â30 Myrâ , and exhibit environmental variation, between and within galaxies. At kpc-scale molecular gas surface densities ÎŁ_(Hâ) â„ 8 M_â pcâ»ÂČâ , the GMC lifetime correlates with time-scales for galactic dynamical processes, whereas at ÎŁ_(Hâ) †8 M_â pcâ»ÂČ GMCs decouple from galactic dynamics and live for an internal dynamical time-scale. After a long inert phase without massive star formation traced by Hâα (75â90 perâcent of the cloud lifetime), GMCs disperse within just 1â5 Myr once massive stars emerge. The dispersal is most likely due to early stellar feedback, causing GMCs to achieve integrated star formation efficiencies of 4â10 perâcent. These results show that galactic star formation is governed by cloud-scale, environmentally dependent, dynamical processes driving rapid evolutionary cycling. GMCs and HâII regions are the fundamental units undergoing these lifecycles, with mean separations of 100â300 pc in star-forming discs. Future work should characterize the multiscale physics and mass flows driving these lifecycles
Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies
We compare the observed turbulent pressure in molecular gas, P_(turb), to the required pressure for the interstellar gas to stay in equilibrium in the gravitational potential of a galaxy, P_(DE). To do this, we combine arcsecond resolution CO data from PHANGS-ALMA with multiwavelength data that trace the atomic gas, stellar structure, and star formation rate (SFR) for 28 nearby star-forming galaxies. We find that P_(turb) correlates withâbut almost always exceedsâthe estimated P_(DE) on kiloparsec scales. This indicates that the molecular gas is overpressurized relative to the large-scale environment. We show that this overpressurization can be explained by the clumpy nature of molecular gas; a revised estimate of P_(DE) on cloud scales, which accounts for molecular gas self-gravity, external gravity, and ambient pressure, agrees well with the observed P_(turb) in galaxy disks. We also find that molecular gas with cloud-scale P_(turb) â P_(DE) âł 10â” kB K cmâ»Âł in our sample is more likely to be self-gravitating, whereas gas at lower pressure it appears more influenced by ambient pressure and/or external gravity. Furthermore, we show that the ratio between P_(turb) and the observed SFR surface density, ÎŁ_(SFR), is compatible with stellar feedback-driven momentum injection in most cases, while a subset of the regions may show evidence of turbulence driven by additional sources. The correlation between ÎŁ_(SFR) and kpc-scale P_(DE) in galaxy disks is consistent with the expectation from self-regulated star formation models. Finally, we confirm the empirical correlation between molecular-to-atomic gas ratio and kpc-scale P_(DE) reported in previous works
Rationale and design of the Multidisciplinary Approach to Novel Therapies in Cardiology Oncology Research Trial (MANTICORE 101 - Breast): a randomized, placebo-controlled trial to determine if conventional heart failure pharmacotherapy can prevent trastuzumab-mediated left ventricular remodeling among patients with HER2+ early breast cancer using cardiac MRI
<p>Abstract</p> <p>Background</p> <p>MANTICORE 101 - Breast (Multidisciplinary Approach to Novel Therapies in Cardiology Oncology Research) is a randomized trial to determine if conventional heart failure pharmacotherapy (angiotensin converting enzyme inhibitor or beta-blocker) can prevent trastuzumab-mediated left ventricular remodeling, measured with cardiac MRI, among patients with HER2+ early breast cancer.</p> <p>Methods/Design</p> <p>One hundred and fifty-nine patients with histologically confirmed HER2+ breast cancer will be enrolled in a parallel 3-arm, randomized, placebo controlled, double-blind design. After baseline assessments, participants will be randomized in a 1:1:1 ratio to an angiotensin-converting enzyme inhibitor (perindopril), beta-blocker (bisoprolol), or placebo. Participants will receive drug or placebo for 1 year beginning 7 days before trastuzumab therapy. Dosages for all groups will be systematically up-titrated, as tolerated, at 1 week intervals for a total of 3 weeks. The primary objective of this randomized clinical trial is to determine if conventional heart failure pharmacotherapy can prevent trastuzumab-mediated left ventricular remodeling among patients with HER2+ early breast cancer, as measured by 12 month change in left ventricular end-diastolic volume using cardiac MRI. Secondary objectives include 1) determine the evolution of left ventricular remodeling on cardiac MRI in patients with HER2+ early breast cancer, 2) understand the mechanism of trastuzumab mediated cardiac toxicity by assessing for the presence of myocardial injury and apoptosis on serum biomarkers and cardiac MRI, and 3) correlate cardiac biomarkers of myocyte injury and extra-cellular matrix remodeling with left ventricular remodeling on cardiac MRI in patients with HER2+ early breast cancer.</p> <p>Discussion</p> <p>Cardiac toxicity as a result of cancer therapies is now recognized as a significant health problem of increasing prevalence. To our knowledge, MANTICORE will be the first randomized trial testing proven heart failure pharmacotherapy in the prevention of trastuzumab-mediated cardiotoxicity. We expect the findings of this trial to provide important evidence in the development of guidelines for preventive therapy.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01016886">NCT01016886</a></p
Plasma Levels of Transforming Growth Factor-ÎČ1 Reflect Left Ventricular Remodeling in Aortic Stenosis
Background: TGF-b1 is involved in cardiac remodeling through an auto/paracrine mechanism. The contribution of TGF-b1
from plasmatic source to pressure overload myocardial remodeling has not been analyzed. We investigated, in patients with
valvular aortic stenosis (AS), and in mice subjected to transverse aortic arch constriction (TAC), whether plasma TGF-b1
relates with myocardial remodeling, reflected by LV transcriptional adaptations of genes linked to myocardial hypertrophy
and fibrosis, and by heart morphology and function.
Methodology/Principal Findings: The subjects of the study were: 39 patients operated of AS; 27 healthy volunteers; 12
mice subjected to TAC; and 6 mice sham-operated. Myocardial samples were subjected to quantitative PCR. Plasma TGF-b1
was determined by ELISA. Under pressure overload, TGF-b1 plasma levels were significantly increased both in AS patients
and TAC mice. In AS patients, plasma TGF-b1 correlated directly with aortic transvalvular gradients and LV mass surrogate
variables, both preoperatively and 1 year after surgery. Plasma TGF-b1 correlated positively with the myocardial expression
of genes encoding extracellular matrix (collagens I and III, fibronectin) and sarcomeric (myosin light chain-2, b-myosin heavy
chain) remodelling targets of TGF-b1, in TAC mice and in AS patients.
Conclusions/Significance: A circulating TGF-b1-mediated mechanism is involved, in both mice and humans, in the
excessive deposition of ECM elements and hypertrophic growth of cardiomyocytes under pressure overload. The possible
value of plasma TGF-b1 as a marker reflecting preoperative myocardial remodeling status in AS patients deserves further
analysis in larger patient cohorts
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