Management of iron-deficiency anemia following acute gastrointestinal hemorrhage: A narrative analysis and review

Many patients experiencing acute gastrointestinal bleeding (GIB) require iron supplemen-tation to treat subsequent iron deficiency (ID) or iron-deficiency anemia (IDA). Guidelinesregarding management of these patients are lacking. We aimed to identify areas of unmetneed in patients with ID/IDA following acute GIB in terms of patient management andphysician guidance. We formed an international working group of gastroenterologists toconduct a narrative review based on PubMed and EMBASE database searches (fromJanuary 2000 to February 2021), integrated with observations from our own clinical expe-rience. Published data on this subject are limited and disparate, and those relating topost-discharge outcomes, such as persistent anemia and re-hospitalization, are particularlylacking. Often, there is no post-discharge follow-up of these patients by a gastroenterolo-gist. Acute GIB-related ID/IDA, however, is a prevalent condition both at the time of hos-pital admission and at hospital discharge and is likely underdiagnosed and undertreated.Despite limited data, there appears to be notable variation in the prescribing of intravenous(IV)/oral iron regimens. There is also some evidence suggesting that, compared with oraliron, IV iron may restore iron levels faster following acute GIB, have a better tolerabilityprofile, and be more beneficial in terms of quality of life. Gaps in patient care exist inthe management of acute GIB-related ID/IDA, yet further data from largepopulation-based studies are needed to confirm this. We advocate the formulation ofevidence-based guidance on the use of iron therapies in these patients, aiding a more stan-dardized best-practice approach to patient care

One Solution to the Mass Budget Problem for Planet Formation: Optically Thick Disks with Dust Scattering

Atacama Large Millimeter Array (ALMA) surveys have suggested that the dust in Class II disks may not be enough to explain the averaged solid mass in exoplanets, under the assumption that the mm disk continuum emission is optically thin. This optically thin assumption seems to be supported by recent Disk Substructures at High Angular Resolution Project (DSHARP) observations where the measured optical depths are mostly less than one. However, we point out that dust scattering can considerably reduce the emission from an optically thick region. If that scattering is ignored, an optically thick disk with scattering can be misidentified as an optically thin disk. Dust scattering in more inclined disks can reduce the intensity even further, making the disk look even fainter. The measured optical depth of ~0.6 in several DSHARP disks can be naturally explained by optically thick dust with an albedo of ~0.9 at 1.25 mm. Using the DSHARP opacity, this albedo corresponds to a dust population with the maximum grain size (s max) of 0.1–1 mm. For optically thick scattering disks, the measured spectral index α can be either larger or smaller than 2 depending on whether the dust albedo increases or decreases with wavelength. We describe how this optically thick scattering scenario could explain the observed scaling between submm continuum sizes and luminosities, and might help ease the tension between the dust size constraints from polarization and dust continuum measurements. We suggest that a significant amount of disk mass can be hidden from ALMA observations and longer wavelength observations (e.g., Very Large Array or Square Kilometre Array) are desired to probe the dust mass in disks

An ALMA survey of DCN/H13^{13}CN and DCO+^+/H13^{13}CO+^+ in protoplanetary disks

The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed throughout the stages of star and planet formation. We present ALMA observations at $\sim0.6"$ resolution of DCO$^+$, H$^{13}$CO$^+$, DCN, and H$^{13}$CN in the full disks around T Tauri stars AS 209 and IM Lup, the transition disks around T Tauri stars V4046 Sgr and LkCa 15, and the full disks around Herbig Ae stars MWC 480 and HD 163296. We also present ALMA observations of HCN in the IM Lup disk. DCN, DCO$^+$, and H$^{13}$CO$^+$ are detected in all disks, and H$^{13}$CN in all but the IM Lup disk. We find efficient deuterium fractionation for the sample, with estimates of disk-averaged DCO$^+$/HCO$^+$ and DCN/HCN abundance ratios ranging from $\sim0.02-0.06$ and $\sim0.005-0.08$, respectively, which is comparable to values reported for other ISM environments. The relative distributions of DCN and DCO$^+$ vary between disks, suggesting that multiple formation pathways may be needed to explain the diverse emission morphologies. In addition, gaps and rings observed in both H$^{13}$CO$^+$ and DCO$^+$ emission provide new evidence that DCO$^+$ bears a complex relationship with the location of the midplane CO snowline.Comment: 36 pages, 14 figures, updated to match figure order of published version in Ap

The Disk Substructures at High Angular Resolution Project (DSHARP). IV. Characterizing Substructures and Interactions in Disks around Multiple Star Systems

To characterize the substructures induced in protoplanetary disks by the interaction between stars in multiple systems, we study the 1.25 mm continuum and the 12CO(J = 2–1) spectral line emission of the triple systems HT Lup and AS 205, at scales of ≈5 au, as part of the Disk Substructures at High Angular Resolution Project (DSHARP). In the continuum emission, we find two symmetric spiral arms in the disk around AS 205 N, with a pitch angle of 14°, while the southern component AS 205 S, itself a spectroscopic binary, is surrounded by a compact inner disk and a bright ring at a radius of 34 au. The 12CO line exhibits clear signatures of tidal interactions, with spiral arms, extended arc-like emission, and high velocity gas, possible evidence of a recent close encounter between the disks in the AS 205 system, as these features are predicted by hydrodynamic simulations of flyby encounters. In the HT Lup system, we detect continuum emission from all three components. The primary disk, HT Lup A, also shows a two-armed symmetric spiral structure with a pitch angle of 4°, while HT Lup B and C, located at 25 and 434 au in projected separation from HT Lup A, are barely resolved with ~5 and ~10 au in diameter, respectively. The gas kinematics for the closest pair indicates a different sense of rotation for each disk, which could be explained by either a counter rotation of the two disks in different, close to parallel, planes, or by a projection effect of these disks with a close to 90° misalignment between them

The Disk Substructures at High Angular Resolution Project (DSHARP). VI. Dust Trapping in Thin-ringed Protoplanetary Disks

A large fraction of the protoplanetary disks observed with ALMA display multiple well-defined and nearly perfectly circular rings in the continuum, in many cases with substantial peak-to-valley contrast. The DSHARP campaign shows that several of these rings are very narrow in radial extent. In this Letter we test the hypothesis that these dust rings are caused by dust trapping in radial pressure bumps, and if confirmed, put constraints on the physics of the dust trapping mechanism. We model this process analytically in 1D, assuming axisymmetry. By comparing this model to the data, we find that all rings are consistent with dust trapping. Based on a plausible model of the dust temperature we find that several rings are narrower than the pressure scale height, providing strong evidence for dust trapping. The rings have peak absorption optical depth in the range between 0.2 and 0.5. The dust masses stored in each of these rings is of the order of tens of Earth masses, though much ambiguity remains due to the uncertainty of the dust opacities. The dust rings are dense enough to potentially trigger the streaming instability, but our analysis cannot give proof of this mechanism actually operating. Our results show, however, that the combination of very low and very large grains can be excluded by the data for all the rings studied in this Letter

The Disk Substructures at High Angular Resolution Program (DSHARP). VIII. The Rich Ringed Substructures in the AS 209 Disk

The Disk Substructures at High Angular Resolution Program (DSHARP). VIII. The Rich Ringed Substructures in the AS 209 Dis

The Disk Substructures at High Angular Resolution Project (DSHARP). VII. The Planet–Disk Interactions Interpretation

The Disk Substructures at High Angular Resolution Project (DSHARP) provides a large sample of protoplanetary disks with substructures that could be induced by young forming planets. To explore the properties of planets that may be responsible for these substructures, we systematically carry out a grid of 2D hydrodynamical simulations, including both gas and dust components. We present the resulting gas structures, including the relationship between the planet mass, as well as (1) the gaseous gap depth/width and (2) the sub/super-Keplerian motion across the gap. We then compute dust continuum intensity maps at the frequency of the DSHARP observations. We provide the relationship between the planet mass, as well as (1) the depth/width of the gaps at millimeter intensity maps, (2) the gap edge ellipticity and asymmetry, and (3) the position of secondary gaps induced by the planet. With these relationships, we lay out the procedure to constrain the planet mass using gap properties, and study the potential planets in the DSHARP disks. We highlight the excellent agreement between observations and simulations for AS 209 and the detectability of the young solar system analog. Finally, under the assumption that the detected gaps are induced by young planets, we characterize the young planet population in the planet mass–semimajor axis diagram. We find that the occurrence rate for \u3e5 M J planets beyond 5–10 au is consistent with direct imaging constraints. Disk substructures allow us to probe a wide-orbit planet population (Neptune to Jupiter mass planets beyond 10 au) that is not accessible to other planet searching techniques

The Disk Substructures at High Angular Resolution Project (DSHARP). III. Spiral Structures in the Millimeter Continuum of the Elias 27, IM Lup, and WaOph 6 Disks

We present an analysis of Atacama Large Millimeter/submillimeter Array 1.25 mm continuum observations of spiral structures in three protoplanetary disks from the Disk Substructures at High Angular Resolution Project. See full text for full abstract

The Disk Substructures at High Angular Resolution Project (DSHARP). II. Characteristics of Annular Substructures

The Disk Substructures at High Angular Resolution Project (DSHARP) used ALMA to map the 1.25 mm continuum of protoplanetary disks at a spatial resolution of ~5 au. We present a systematic analysis of annular substructures in the 18 single-disk systems targeted in this survey. No dominant architecture emerges from this sample; instead, remarkably diverse morphologies are observed. Annular substructures can occur at virtually any radius where millimeter continuum emission is detected and range in widths from a few astronomical units to tens of astronomical units. Intensity ratios between gaps and adjacent rings range from near-unity to just a few percent. In a minority of cases, annular substructures coexist with other types of substructures, including spiral arms (3/18) and crescent-like azimuthal asymmetries (2/18). No clear trend is observed between the positions of the substructures and stellar host properties. In particular, the absence of an obvious association with stellar host luminosity (and hence the disk thermal structure) suggests that substructures do not occur preferentially near major molecular snowlines. Annular substructures like those observed in DSHARP have long been hypothesized to be due to planet–disk interactions. A few disks exhibit characteristics particularly suggestive of this scenario, including substructures in possible mean-motion resonance and double gap features reminiscent of hydrodynamical simulations of multiple gaps opened by a planet in a low-viscosity disk