25 research outputs found
MINDS. JWST-MIRI Reveals a Dynamic Gas-Rich Inner Disk Inside the Cavity of SY Cha
SY Cha is a T Tauri star surrounded by a protoplanetary disk with a large
cavity seen in the millimeter continuum but has the spectral energy
distribution (SED) of a full disk. Here we report the first results from
JWST-MIRI Medium Resolution Spectrometer (MRS) observations taken as part of
the MIRI mid-INfrared Disk Survey (MINDS) GTO Program. The much improved
resolution and sensitivity of MIRI-MRS compared to Spitzer enables a robust
analysis of the previously detected H2O, CO, HCN, and CO2 emission as well as a
marginal detection of C2H2. We also report the first robust detection of
mid-infrared OH and ro-vibrational CO emission in this source. The derived
molecular column densities reveal the inner disk of SY Cha to be rich in both
oxygen and carbon bearing molecules. This is in contrast to PDS 70, another
protoplanetary disk with a large cavity observed with JWST, which displays much
weaker line emission. In the SY Cha disk, the continuum, and potentially the
line, flux varies substantially between the new JWST observations and archival
Spitzer observations, indicative of a highly dynamic inner disk.Comment: 19 pages, 10 figures, 5 tables, accepted for publication in Ap
MINDS. Abundant water and varying C/O across the disk of Sz 98 as seen by JWST/MIRI
MIRI/MRS on board the JWST allows us to probe the inner regions of
protoplanetary disks. Here we examine the disk around the classical T Tauri
star Sz 98, which has an unusually large dust disk in the millimetre with a
compact core. We focus on the HO emission through both its ro-vibrational
and pure rotational emission. Furthermore, we compare our chemical findings
with those obtained for the outer disk from Atacama Large
Millimeter/submillimeter Array (ALMA) observations. In order to model the
molecular features in the spectrum, the continuum was subtracted and LTE slab
models were fitted. The spectrum was divided into different wavelength regions
corresponding to HO lines of different excitation conditions, and the slab
model fits were performed individually per region. We confidently detect CO,
HO, OH, CO, and HCN in the emitting layers. The isotopologue
HO is not detected. Additionally, no other organics, including
CH, are detected. This indicates that the C/O ratio could be
substantially below unity, in contrast with the outer disk. The HO emission
traces a large radial disk surface region, as evidenced by the gradually
changing excitation temperatures and emitting radii. The OH and CO emission
are relatively weak. It is likely that HO is not significantly
photodissociated; either due to self-shielding against the stellar irradiation,
or UV-shielding from small dust particles. The relative emitting strength of
the different identified molecular features point towards UV-shielding of
HO in the inner disk of Sz 98, with a thin layer of OH on top. The majority
of the organic molecules are either hidden below the dust continuum, or not
present. In general, the inferred composition points to a sub-solar C/O ratio
(<0.5) in the inner disk, in contrast with the larger than unity C/O ratio in
the gas in the outer disk found with ALMA.Comment: Submitted to A&A on May 25 2023. 18 pages, 11 figure
MINDS: The JWST MIRI Mid-INfrared Disk Survey
The study of protoplanetary disks has become increasingly important with the
Kepler satellite finding that exoplanets are ubiquitous around stars in our
galaxy and the discovery of enormous diversity in planetary system
architectures and planet properties. High-resolution near-IR and ALMA images
show strong evidence for ongoing planet formation in young disks. The JWST MIRI
mid-INfrared Disk Survey (MINDS) aims to (1) investigate the chemical inventory
in the terrestrial planet-forming zone across stellar spectral type, (2) follow
the gas evolution into the disk dispersal stage, and (3) study the structure of
protoplanetary and debris disks in the thermal mid-IR. The MINDS survey will
thus build a bridge between the chemical inventory of disks and the properties
of exoplanets. The survey comprises 52 targets (Herbig Ae stars, T Tauri stars,
very low-mass stars and young debris disks). We primarily obtain MIRI/MRS
spectra with high S/N (~100-500) covering the complete wavelength range from
4.9 to 27.9 {\mu}m. For a handful of selected targets we also obtain NIRSpec
IFU high resolution spectroscopy (2.87-5.27 {\mu}m). We will search for
signposts of planet formation in thermal emission of micron-sized dust -
information complementary to near-IR scattered light emission from small dust
grains and emission from large dust in the submillimeter wavelength domain. We
will also study the spatial structure of disks in three key systems that have
shown signposts for planet formation, TW Hya and HD 169142 using the MIRI
coronagraph at 15.5 {\mu}m and 10.65 {\mu}m respectively and PDS70 using NIRCam
imaging in the 1.87 {\mu}m narrow and the 4.8 {\mu}m medium band filter. ...Comment: accepted for publication in PAS
MINDS. The detection of CO with JWST-MIRI indicates abundant CO in a protoplanetary disk
We present JWST-MIRI MRS spectra of the protoplanetary disk around the
low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey (MINDS) GTO
program. Emission from CO, CO, HO, HCN,
CH, and OH is identified with CO being detected for
the first time in a protoplanetary disk. We characterize the chemical and
physical conditions in the inner few au of the GW Lup disk using these
molecules as probes. The spectral resolution of JWST-MIRI MRS paired with high
signal-to-noise data is essential to identify these species and determine their
column densities and temperatures. The -branches of these molecules,
including those of hot-bands, are particularly sensitive to temperature and
column density. We find that the CO emission in the GW Lup disk is
coming from optically thick emission at a temperature of 400 K.
CO is optically thinner and based on a lower temperature of
325 K, may be tracing deeper into the disk and/or a larger emitting
radius than CO. The derived /
ratio is orders of magnitude higher than previously derived for GW Lup and
other targets based on \textit{Spitzer}-IRS data. This high column density
ratio may be due to an inner cavity with a radius in between the HO and
CO snowlines and/or an overall lower disk temperature. This paper
demonstrates the unique ability of JWST to probe inner disk structures and
chemistry through weak, previously unseen molecular features.Comment: 15 pages, 10 figures. Accepted to ApJ
Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021
Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic
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Preemptive Appendicectomy at the Time of Pancreas Transplantation: Is It Necessary?
Objectives: Pancreas transplant is a major intra-abdominal operation, and in most cases the graft is placed in the right iliac fossa. At our center, preemptive appendicectomy is performed at the time of pancreas transplant to prevent any future risk in a complex transplant patient. The aim of this study was to review all histology reports from the removed appendices.
Materials and Methods:The histology reports from all incidental appendicectomies performed at pancreas transplant were reviewed.
Results: Between January 2001 and June 2016, 107 pancreas transplants were performed (86 simultaneous pancreas and kidney transplants, 11 pancreas after kidney transplants, and 10 pancreas transplants alone), and 65 appendix histology reports were available from this patient group. All were preemptive appendicectomies as none of the patients had symptoms to suggest acute appendicitis. Of the 65 appendix histologies, 43 (66.2%) were reported as normal. Twenty specimens (30.8%) showed fibrosis consistent with previous inflammation of the appendix, and 12 specimens (18.5%) showed fecal material in the lumen (1 due to an obstructing fecalith and another 2 showing lumina! distension with feces). Three specimens (4.6%) showed lymphoid hyperplasia. There were 5 (7.7 %) unexpected findings upon histology. In review of histology reports, 1 patient had a 1.1-mm carcinoid tumor in an otherwise normal appendix, 1 had an Enterobius species worm infestation, 1 had focal endometriosis, 1 had crypt abscesses suggestive of inflammatory bowel disease, 1 had a metaplastic polyp, and 1 had melanosis coli of unknown clinical significance. There were no cases of overt acute appendicitis. No patients experienced a complication as a direct result of their appendicectomy.
Conclusions:A policy of routine appendicectomy at the time of pancreas transplant appears to be justified and safe
MINDS. JWST/MIRI Reveals a Dynamic Gas-rich Inner Disk inside the Cavity of SY Cha
SY Cha is a T Tauri star surrounded by a protoplanetary disk with a large cavity seen in the millimeter continuum but has the spectral energy distribution of a full disk. Here we report the first results from JWST/Mid-InfraRed Instrument (MIRI) Medium Resolution Spectrometer (MRS) observations taken as part of the MIRI mid-INfrared Disk Survey (MINDS) GTO Program. The much improved resolution and sensitivity of MIRI-MRS compared to Spitzer enables a robust analysis of the previously detected H2O, CO, HCN, and CO2 emission as well as a marginal detection of C2H2. We also report the first robust detection of mid-infrared OH and rovibrational CO emission in this source. The derived molecular column densities reveal the inner disk of SY Cha to be rich in both oxygen- and carbon-bearing molecules. This is in contrast to PDS 70, another protoplanetary disk with a large cavity observed with JWST, which displays much weaker line emission. In the SY Cha disk, the continuum, and potentially the line, flux varies substantially between the new JWST observations and archival Spitzer observations, indicative of a highly dynamic inner disk.</p