Context.
The evolution of protoplanetary disks is regulated by an interplay of several processes, either internal to the system or related to the environment. As most of the stars and planets, ...including our own Solar System, have formed in massive stellar clusters that contain OB-type stars, studying the effects of UV radiation on disk evolution is of paramount importance.
Aims.
For this work, we tested the impact of external photoevaporation on the evolution of disks in the mid-age (~3–5 Myr)
σ
-Orionis cluster by conducting the first combined large-scale UV to IR spectroscopic and millimeter-continuum survey of this region.
Methods.
We studied a sample of 50 targets located at increasing distances from the central, massive OB system
σ
-Ori. We combined new spectra obtained with VLT/X-shooter, used to measure mass accretion rates and stellar masses, with new and previously published ALMA measurements of disk dust and gas fluxes and masses.
Results.
We confirm the previously found decrease in
M
dust
in the inner ~0.5 pc of the cluster. This is particularly evident when considering the disks around the more massive stars (≥0.4
M
⊙
), where those located in the inner part (<0.5 pc) of the cluster have
M
dust
about an order of magnitude lower than the more distant ones. About half of the sample is located in the region of the
Ṁ
acc
versus
M
disk
expected by models of external photoevaporation, namely showing shorter disk lifetimes than expected for their ages. The shorter disk lifetimes is observed for all targets with a projected separation from
σ
-Ori < 0.5 pc, proving that the presence of a massive stellar system affects disk evolution.
Conclusions.
External photoevaporation is a viable mechanism to explain the observed shorter disk lifetimes and lower
M
dust
in the inner ~0.5 pc of the
σ
-Orionis cluster, where the effects of this process are more pronounced. Follow-up observations of the low stellar mass targets are crucial to constrain disk dispersion timescales in the cluster and to confirm the dependence of the external photoevaporation process with stellar host mass. This work confirms that the effects of external photoevaporation are significant down to at least impinging radiation as low as ~10
4
G
0
.
Early results from the James Webb Space Telescope-Mid-InfraRed Instrument (JWST-MIRI) guaranteed time programs on protostars (JOYS) and disks (MINDS) are presented. Thanks to the increased ...sensitivity, spectral and spatial resolution of the MIRI spectrometer, the chemical inventory of the planet-forming zones in disks can be investigated with unprecedented detail across stellar mass range and age. Here, data are presented for five disks, four around low-mass stars and one around a very young high-mass star. The mid-infrared spectra show some similarities but also significant diversity: some sources are rich in CO
2
, others in H
2
O or C
2
H
2
. In one disk around a very low-mass star, booming C
2
H
2
emission provides evidence for a "soot" line at which carbon grains are eroded and sublimated, leading to a rich hydrocarbon chemistry in which even di-acetylene (C
4
H
2
) and benzene (C
6
H
6
) are detected. Together the data point to an active inner disk gas-phase chemistry that is closely linked to the physical structure (temperature, snowlines, presence of cavities and dust traps) of the entire disk and which may result in varying CO
2
/H
2
O abundances and high C/O ratios >1 in some cases. Ultimately, this diversity in disk chemistry will also be reflected in the diversity of the chemical composition of exoplanets.
Early results from JWST-MIRI programs on low- and high-mass protostars and disks show significant diversity in their mid-infrared spectra, most notably for CO
2
, H
2
O and C
2
H
2
. Benzene is detected in disks around very low mass stars.
Background: Thrombotic thrombocytopenic purpura (TTP) is a rare life‐threatening disease. Of surviving patients, 45% develops an exacerbation or a late recurrence. Severe ADAMTS‐13 deficiency, both ...during the acute episode and remission, is a well‐established predictor of recurrence. The predictive value of anti‐ADAMTS‐13 antibodies, their inhibitory activity and Ig class subtype for disease recurrence is still to be established.
Objectives: To analyze ADAMTS‐13‐related biomarkers (ADAMTS‐13 and anti‐ADAMTS‐13 immunoglobulins, classes and subclasses) and their potential relationship with prognosis.
Patients/Methods: In 115 patients with TTP, we assessed the association between levels of these biomarkers and the severity of acute episodes; we analysed also the hazard ratio (HR) and 95% confidence interval (CI) of recurrence in association with biomarkers levels retrieved at the previous acute episode or during remission, using Cox regression models.
Results: During the acute phase, higher IgA, IgG1 and IgG3 titers showed the strongest association with acute episode severity. In the survival analyzes, the only biomarker significantly associated with a high hazard of recurrence after an acute episode was the presence of IgG. Conversly, low ADAMTS‐13 activity or antigen levels (< 10%), the presence of ADAMTS‐13 inhibitor or IgG during remission were all significantly associated with a higher hazard of recurrence.
Conclusions: Both the Ig class and subclass are of predictive value for acute episode severity in patients with TTP. Although markers that could predict the risk of recurrence in the acute phase are limited, a thorough assessment of ADAMTS‐13‐related parameters during remission is warranted.
In this paper, we study how a government should set its fiscal instruments in order to provide insurance to individuals and deal with inequality. We quantitatively evaluate the role of public debt ...and its interaction with progressive income taxation. To guide our assessment, we develop a DSGE model with incomplete markets that embeds two empirical relevant features that have not been considered by the literature: cyclical idiosyncratic risk and the extensive margin of labor supply. We calibrate the model to be consistent with the micro and macro evidence for the US economy. We study the importance of time-varying idiosyncratic risk and labor supply elasticity in determining optimal policies by considering two nested versions of the model that shut down one feature at a time. We find that considering both ingredients together significantly increases the optimal debt to output ratio. In addition, we show that the model generates a positive relationship between public debt and income tax progressivity, consistent to what is observed in the data.
Abstract In many countries, the structure of wages and the labor law legislation are completely different for public and private sector employees. In this paper, we develop a general equilibrium ...overlapping generations model to study the effect of such differences on household savings and labor supply. To conduct our analysis, first we use microdata from two Brazilian household surveys to document that civil servants save and work significantly less than their counterparts in the private sector. Second, we use matched employer–employee microdata from Brazil (RAIS) to document differences between the two sectors in terms of wage and unemployment risk. Then, we calibrate the model to be consistent with micro and macro evidence for Brazil. Our counterfactual exercises show that differences in wages characteristics and labor law legislation account for nearly 70% of the gap in savings between civil servants and private sector workers, and 57% of the gap in labor supply. In addition, we find that eliminating those differences can produce sizable increase on aggregate savings, employment, and welfare.
An important stylized fact about public sector employment is that it predominantly hires skilled and more experienced workers. In this paper, we consider a search and matching model with public ...sector and on-the-job human capital accumulation that incorporates this stylized fact to study how the public sector employment affects the labor market volatility. In the model, public sector employment affects aggregate fluctuations by changing the composition of workers employed in the private sector. Because workers accumulate human capital and become more productive when employed, the flow of benefits from forming a match are spread over time. In this environment, if the flow into the public sector increases with human capital, then the government hiring policy decreases the firm’s benefit of hiring and the matching surplus, increasing the responsiveness of labor market tightness to shocks. We calibrate the model for the Brazilian economy and show that this mechanism amplifies the effects of public employment on vacancy creation and private sector employment volatility.
We have analysed the association between alcohol drinking before and during the three trimesters of pregnancy and risk of preterm birth of babies with normal weight for gestational age or with low ...weight for gestational age (SGA).
Case-control study.
General and university hospitals in Italy.
Cases were 502 women who delivered preterm births <37 weeks gestation. The controls included 1966 women who gave birth at term (>/=37 weeks of gestation) to healthy infants of normal weight (ie between 10th and 90th centile according to the Italian standard) on randomly selected days at the hospitals where cases had been identified.
Interview.
No increased risk of preterm birth was observed in women drinking one or two drinks/die in pregnancy, but three or more drinks/die increased the risk (multivariate odds ratios (OR) 2.0 for >/=3 drinks during the first trimester, 1.8 during the second and 1.9 during the third). When the analysis was conducted separately for preterm births with normal weight or SGA, the increased risk was observed in preterm SGA only (multivariate OR for >/=3 drinks/die during the first trimester=3.6, 95% confidence interval (CI) 1.3-11.1); the estimated multivariate OR for >/=3 drinks/die during the first trimester of preterm babies with normal weight for gestational age was only slightly above unity and not statistically significant (multivariate OR 1.4, 95% CI 0.5-3.7).
The study shows an increased risk in mothers who drink >/=3 die units alcohol in pregnancy of preterm births.
The purpose of this study was to evaluate long-term results in patients who received conservative surgical treatment for rectovaginal endometriosis.
We analyzed the follow-up data for 83 women who ...underwent surgery for rectovaginal endometriosis. The inclusion criteria were age 20 to 42 years, moderate-to-severe pain symptoms, conservative treatment with retention of the uterus, and at least 1 ovary; the follow-up period was ≥12 months. Kaplan-Meier analysis and Cox regression were used to calculate recurrence rates.
The cumulative rates of pain recurrence, clinical or sonographic recurrence, and new treatment were 28%, 34%, and 27%, respectively. The younger patients had the higher risk of recurrence. Pregnancy had protective effects against the recurrence of symptoms and a need for a new treatment. Patients who underwent bowel resection had fewer recurrences.
Segmental resection and anastomosis of the bowel, when necessary, improves the outcome without affecting chances of conception. Higher recurrence rates in younger patients seems to justify a more radical treatment in this group of women.
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