We present the stacking analysis of a sample of 48 quasi-stellar objects (QSOs) at 4.5 < z < 7.1 detected by the Atacama Large Millimetre Array (ALMA) in the CII λ158 μm emission line to ...investigate the presence and the properties of massive, cold outflows associated with broad wings in the CII profile. The high sensitivity reached through this analysis allows us to reveal very broad CII wings tracing the presence of outflows with velocities in excess of 1000 km s−1. We find that the luminosity of the broad CII emission increases with LAGN, while it does not significantly depend on the star formation rate of the host galaxy, indicating that the central active galactic nucleus (AGN) is the main driving mechanism of the CII outflows in these powerful, distant QSOs. From the stack of the ALMA cubes, we derive an average outflow spatial extent of ∼3.5 kpc. The average atomic neutral mass outflow rate inferred from the stack of the whole sample is Ṁout ∼ 100 M⊙ yr−1, while for the most luminous systems it increases to ∼200 M⊙ yr−1. The associated outflow kinetic power is about 0.1% of LAGN, while the outflow momentum rate is ∼LAGN/c or lower, suggesting that these outflows are either driven by radiation pressure onto dusty clouds or, alternatively, are driven by the nuclear wind and energy conserving but with low coupling with the interstellar medium. We discuss the implications of the resulting feedback effect on galaxy evolution in the early Universe.
Context. Feedback from accreting supermassive black holes (SMBHs) is often identified as the main mechanism responsible for regulating star formation in active galactic nucleus (AGN) host galaxies. ...However, the relationships between AGN activity, radiation, winds, and star formation are complex and still far from being understood. Aims. We study scaling relations between AGN properties, host galaxy properties, and AGN winds. We then evaluate the wind mean impact on the global star formation history, taking into account the short AGN duty cycle with respect to that of star formation. Methods. We first collect AGN wind observations for 94 AGN with detected massive winds at sub-pc to kpc spatial scales. We then fold AGN wind scaling relations with AGN luminosity functions, to evaluate the average AGN wind mass-loading factor as a function of cosmic time. Results. We find strong correlations between the AGN molecular and ionised wind mass outflow rates and the AGN bolometric luminosity. The power law scaling is steeper for ionised winds (slope 1.29 ± 0.38) than for molecular winds (0.76 ± 0.06), meaning that the two rates converge at high bolometric luminosities. The molecular gas depletion timescale and the molecular gas fraction of galaxies hosting powerful AGN driven winds are 3–10 times shorter and smaller than those of main sequence galaxies with similar star formation rate (SFR), stellar mass, and redshift. These findings suggest that, at high AGN bolometric luminosity, the reduced molecular gas fraction may be due to the destruction of molecules by the wind, leading to a larger fraction of gas in the atomic ionised phase. The AGN wind mass-loading factor η = ṀOF/SFR is systematically higher than that of starburst driven winds. Conclusions. Our analysis shows that AGN winds are, on average, powerful enough to clean galaxies from their molecular gas only in massive systems at z ≲ 2, i.e. a strong form of co-evolution between SMBHs and galaxies appears to break down for the least massive galaxies.
Adult stem cell (SC) maintenance and differentiation are known to depend on signals received from the niche. Here, however, we demonstrate a mechanism for SC specification and regulation that is ...niche independent. Using immunofluorescence, live imaging, genetics, cell-cycle analyses, in utero lentiviral transduction, and lineage-tracing, we show that in developing hair buds, SCs are born from asymmetric divisions that differentially display WNT and SHH signaling. Displaced WNTlo suprabasal daughters become SCs that respond to paracrine SHH and symmetrically expand. By contrast, basal daughters remain WNThi. They express but do not respond to SHH and hence maintain slow-cycling, asymmetric divisions. Over time, they become short-lived progenitors, generating differentiating daughters rather than SCs. Thus, in contrast to an established niche that harbors a fixed SC pool whose expelled progeny differentiate, asymmetric divisions first specify and displace early SCs into an environment conducive to expansion and later restrict their numbers by switching asymmetric fates.
Display omitted
•Asymmetric divisions within hair buds differentially partition WNT and SHH signaling•This partitioning couples asymmetric cell division to asymmetric cell fate•WNTlo daughters that respond to, but do not produce, SHH expand symmetrically•WNThi SHH-producing cells ultimately cease producing stem cell daughters
A mechanism for specifying stem cell numbers and identity that is independent of a physical niche operates during skin development: reciprocal signaling between an asymmetrically dividing and transient population of cells and their fast-cycling, symmetrically dividing sisters fuels the regulatory system.
Background Early mobilization is considered an important element of postoperative care; however, how best to implement this intervention in clinical practice is unknown. This systematic review ...summarizes the evidence regarding the impact of specific early mobilization protocols on postoperative outcomes after abdominal and thoracic surgery. Method The review was performed according to PRISMA guidelines. We searched 8 electronic databases to identify studies comparing patients receiving a specific protocol of early mobilization to a control group. Methodologic quality was assessed using the Downs and Black tool. Results Four studies in abdominal surgery (3 randomized controlled trials RCTs and 1 observational prospective study) and 4 studies in thoracic surgery (3 RCTs and 1 observational retrospective study) were identified. None of the 5 studies evaluating postoperative complications reported differences between groups. One of 4 studies evaluating duration of stay reported a significant decrease in the intervention group. One of 3 studies evaluating gastrointestinal function reported differences in favor of the intervention group. One of 4 studies evaluating performance-based outcomes reported differences in favor of the intervention group. One of 5 studies evaluating patient-reported outcomes reported differences in favor of the intervention group. Overall methodologic quality was poor. Conclusion Few comparative studies have evaluated the impact of early mobilization protocols on outcomes after abdominal and thoracic surgery. The quality of these studies was poor and results were conflicting. Although bed rest is harmful, there is little available evidence to guide clinicians in effective early mobilization protocols that increase mobilization and improve outcomes.
At the body surface, skin's stratified squamous epithelium is challenged by environmental extremes. The surface of the skin is composed of enucleated, flattened surface squames. They derive from ...underlying, transcriptionally active keratinocytes that display filaggrin-containing keratohyalin granules (KGs) whose function is unclear. Here, we found that filaggrin assembles KGs through liquid-liquid phase separation. The dynamics of phase separation governed terminal differentiation and were disrupted by human skin barrier disease-associated mutations. We used fluorescent sensors to investigate endogenous phase behavior in mice. Phase transitions during epidermal stratification crowded cellular spaces with liquid-like KGs whose coalescence was restricted by keratin filament bundles. We imaged cells as they neared the skin surface and found that environmentally regulated KG phase dynamics drive squame formation. Thus, epidermal structure and function are driven by phase-separation dynamics.
Mrk 231 is a nearby ultra-luminous IR galaxy exhibiting a kpc-scale, multi-phase AGN-driven outflow. This galaxy represents the best target to investigate in detail the morphology and energetics of ...powerful outflows, as well as their still poorly-understood expansion mechanism and impact on the host galaxy. In this work, we present the best sensitivity and angular resolution maps of the molecular disk and outflow of Mrk 231, as traced by CO(2−1) and (3−2) observations obtained with the IRAM/PdBI. In addition, we analyze archival deep Chandra and NuSTAR X-ray observations. We use this unprecedented combination of multi-wavelength data sets to constrain the physical properties of both the molecular disk and outflow, the presence of a highly-ionized ultra-fast nuclear wind, and their connection. The molecular CO(2−1) outflow has a size of ~1 kpc, and extends in all directions around the nucleus, being more prominent along the south-west to north-east direction, suggesting a wide-angle biconical geometry. The maximum projected velocity of the outflow is nearly constant out to ~1 kpc, thus implying that the density of the outflowing material must decrease from the nucleus outwards as ~r-2. This suggests that either a large part of the gas leaves the flow during its expansion or that the bulk of the outflow has not yet reached out to ~1 kpc, thus implying a limit on its age of ~1 Myr. Mapping the mass and energy rates of the molecular outflow yields \hbox{$\rm \dot {\it M}$}M˙ OF = 500−1000 M⊙ yr-1 and Ėkin,OF = 7−10 × 1043 erg s-1. The total kinetic energy of the outflow is Ekin,OF is of the same order of the total energy of the molecular disk, Edisk. Remarkably, our analysis of the X-ray data reveals a nuclear ultra-fast outflow (UFO) with velocity −20 000 km s-1, \hbox{$\rm \dot {\it M}$} M ˙ UFO = 0.3−2.1 M⊙ yr-1, and momentum load \hbox{$\rm \dot {\it P}$} P ˙ UFO/ \hbox{$\dot {\it P}$} P ˙ rad = 0.2−1.6. We find Ėkin,UFO ~ Ėkin,OF as predicted for outflows undergoing an energy conserving expansion. This suggests that most of the UFO kinetic energy is transferred to mechanical energy of the kpc-scale outflow, strongly supporting that the energy released during accretion of matter onto super-massive black holes is the ultimate driver of giant massive outflows. The momentum flux \hbox{$\rm \dot {\it P}$} P ˙ OF derived for the large scale outflows in Mrk 231 enables us to estimate a momentum boost \hbox{$\rm \dot {\it P}$} P ˙ OF/ \hbox{$\dot {\it P}$} P ˙ UFO ≈ 30−60. The ratios Ėkin,UFO/Lbol,AGN = 1−5 % and Ėkin,OF/Lbol,AGN = 1−3 % agree with the requirements of the most popular models of AGN feedback.
To investigate the feasibility of SDD protocol with postdischarge follow-up using a mobile phone app in patients undergoing elective minimally-invasive colectomy.
Discharge before gastrointestinal ...recovery and use of mobile health technology for remote follow-up may allow for SDD after minimally-invasive colectomy within an ERP.
Adult patients undergoing elective laparoscopic colectomy or loop ileostomy reversal from February 2020 to November 2020 were screened for eligibility. Patients were eligible if they lived within a 30-minute drive from the hospital, had an adequate support system at home, and owned a smart phone. Patients were discharged from the recovery room on the day of surgery based on set criteria with postdischarge remote follow-up using a mobile application. Feasibility was defined as discharge on the day of surgery without emergency department (ED) visit or readmission within the first 3 days. 30-day complications, ED visits, and readmissions were compared to a non-SDD historical cohort (May 2019-March 2020) also remotely followed-up using the same mobile phone app (standard ERP group).
A total of 48 patients were recruited to SDD, of which 77% were discharged on the day of surgery without subsequent ED visit in the first 72 hours. There were 11 patients that could not be discharged, including 7 for failure of discharge criteria and 4 for intraoperative complications/concerns. Overall 30-day complications in the SDD group (17%) was similar to the standard ERP group (15%, P = 0.813). ED visits (SDD10% vs standard ERP8%, P = 0.664) and readmissions (6% vs 4%, P = 0.681) were also similar.
Findings from this study support the feasibility of a SDD protocol in select patients undergoing minimally-invasive colorectal resection. SDD colectomy protocols may represent the next evolution of ERP and postoperative recovery.
Using a state-of-the-art semi analytic model for galaxy formation, we investigated in detail the effects of black hole (BH) accretion triggered by disk instabilities (DI) in isolated galaxies on the ...evolution of the AGN population. Specifically, we took on, developed, and expanded the Hopkins & Quataert (2011, MNRAS, 411, 1027) model for the mass inflow following disk perturbations, based on a physical description of nuclear inflows and tested against aimed N-body simulations. We compared the evolution of AGN due to such a DI accretion mode with that arising in a scenario where galaxy interactions (IT mode) produce the sudden destabilization of large quantities of gas feeding the AGN; this constitutes the standard AGN feeding mode implemented in the earliest versions of most semi-analytic models. To study the maximal contribution of DI to the evolution of the AGN population, we extended and developed the DI model to assess the effects of changing the assumed disk surface density profile, and to obtain lower limits for the nuclear star formation rates associated to the DI accretion mode. We obtained the following results: i) For AGN with luminosity M1450 ≳ − 26, the DI mode can provide the BH accretion needed to match the observed AGN luminosity functions up to z ≈ 4.5. In such a luminosity range and redshift, it constitutes a viable candidate mechanism to fuel AGN, and can compete with the IT scenario as the main driver of cosmological evolution of the AGN population. ii) The DI scenario cannot provide the observed abundance of high-luminosity QSO with M1450 ≤ −26 AGN, as well as the abundance of high-redhshift z ≳ 4.5 QSO with M1450 ≤ −24. As found in our earliest works, the IT scenario provides an acceptable match to the observed luminosity functions up to z ≈ 6. iii) The dispersion of the distributions of Eddington ratio λ for low- and intermediate-luminosity AGN (bolometric LAGN = 1043−1045 erg s-1) is predicted to be much smaller in the DI scenario compared to the IT mode. iv) The above conclusions concerning the DI mode are robust with respect to the explored variants of the DI model. We discuss the physical origin of our findings. Finally, we discuss how it is possible to pin down the dominant fueling mechanism of AGN in the low-intermediate luminosity range M1450 ≳ −26 where the DI and the IT modes are both viable candidates as the main drivers of the AGN evolution. We show that an interesting discriminant could be provided by the fraction of AGN with high Eddington ratios λ ≥ 0.5, since it increases with luminosity in the IT case, while the opposite is true in the DI scenario.
We study the properties of massive, galactic-scale outflows of molecular gas and investigate their impact on galaxy evolution. We present new IRAM PdBI CO(1–0) observations of local ultra-luminous ...infrared galaxies (ULIRGs) and quasar-hosts: a clear signature of massive and energetic molecular outflows, extending on kpc scales, is found in the CO(1–0) kinematics of four out of seven sources, with measured outflow rates of several 100 M⊙ yr-1. We combine these new observations with data from the literature, and explore the nature and origin of massive molecular outflows within an extended sample of 19 local galaxies. We find that starburst-dominated galaxies have an outflow rate comparable to their star formation rate (SFR), or even higher by a factor of ~2–4, implying that starbursts can indeed be effective in removing cold gas from galaxies. Nevertheless, our results suggest that the presence of an active galactic nucleus (AGN) can boost the outflow rate by a large factor, which is found to increase with the LAGN/Lbol ratio. The gas depletion time scales due to molecular outflows are anti-correlated with the presence and luminosity of an AGN in these galaxies, and range from a few hundred million years in starburst galaxies down to just a few million years in galaxies hosting powerful AGNs. In quasar hosts, the depletion time scales due to the outflow are much shorter than the depletion time scales due to star formation. We estimate the outflow kinetic power and find that, for galaxies hosting powerful AGNs, it corresponds to about 5% of the AGN luminosity, as expected by models of AGN feedback. Moreover, we find that momentum rates of about 20 LAGN/c are common among the AGN-dominated sources in our sample. For “pure” starburst galaxies, our data tentatively support models in which outflows are mostly momentum-driven by the radiation pressure from young stars onto dusty clouds. Overall, our results indicate that, although starbursts are effective in powering massive molecular outflows, the presence of an AGN may strongly enhance such outflows, and therefore have a profound feedback effect on the evolution of galaxies by efficiently removing fuel for star formation, hence quenching star formation.
Evidence of strong quasar feedback in the early Universe Maiolino, R.; Gallerani, S.; Neri, R. ...
Monthly notices of the Royal Astronomical Society. Letters,
September 2012, 2012-09-01, 20120901, Letnik:
425, Številka:
1
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
Most theoretical models invoke quasar‐driven outflows to quench star formation in massive galaxies, and this feedback mechanism is required to account for the population of old and passive ...galaxies observed in the local Universe. The discovery of massive, old and passive galaxies at z∼ 2 implies that such quasar feedback on to the host galaxy must have been at work very early on, close to the reionization epoch. We have observed the C ii 158 m transition in SDSS J114816.64+525150.3, which, at z= 6.4189, is one of the most distant quasars known. We detect broad wings of the line tracing a quasar‐driven massive outflow. This is the most distant massive outflow ever detected and is likely tracing the long‐sought quasar feedback, already at work in the early Universe. The outflow is marginally resolved on scales of ∼16 kpc, implying that the outflow can really affect the whole galaxy, as required by quasar feedback models. The inferred outflow rate, , is the highest ever found. At this rate, the outflow can clean the gas in the host galaxy, and therefore quench star formation, in a few million years.
PDF
