We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years ...away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.
The late-time optical and near-IR line profiles of many core-collapse supernovae exhibit a red-blue asymmetry as a result of greater extinction by internal dust of radiation emitted from the receding ...parts of the supernova ejecta. We present here a new code, DAMOCLES, that models the effects of dust on the line profiles of core-collapse supernovae in order to determine newly formed dust masses. We find that late-time dust-affected line profiles may exhibit an extended red scattering wing (as noted by Lucy et al. 1989) and that they need not be flux-biased towards the blue, although the profile peak will always be blueshifted. We have collated optical spectra of SN 1987A from a variety of archival sources and have modelled the Hα line from days 714 to 3604 and the O i 6300,6363 Å doublet between days 714 and 1478. Our line profile fits rule out day 714 dust masses >3 × 10−3 M⊙ for all grain types apart from pure magnesium silicates, for which no more than 0.07 M⊙ can be accommodated. Large grain radii ( ≥ 0.6 μm) are generally required to fit the line profiles even at the earlier epochs. We find that a large dust mass (≥0.1 M⊙) had formed by day 3604 and infer that the majority of the present dust mass must have formed after this epoch. Our findings agree with recent estimates from spectral energy distribution fits for the dust mass evolution of SN 1987A and support the inference that the majority of SN 1987A's dust formed many years after the initial explosion.
ABSTRACT We have constructed mocassin photoionization plus dust radiative transfer models for the Crab Nebula core-collapse supernova (CCSN) remnant, using either smooth or clumped mass ...distributions, in order to determine the chemical composition and masses of the nebular gas and dust. We computed models for several different geometries suggested for the nebular matter distribution but found that the observed gas and dust spectra are relatively insensitive to these geometries, being determined mainly by the spectrum of the pulsar wind nebula which ionizes and heats the nebula. Smooth distribution models are ruled out since they require 16-49 M of gas to fit the integrated optical nebular line fluxes, whereas our clumped models require 7.0 M of gas. A global gas-phase C/O ratio of 1.65 by number is derived, along with a He/H number ratio of 1.85, neither of which can be matched by current CCSN yield predictions. A carbonaceous dust composition is favored by the observed gas-phase C/O ratio: amorphous carbon clumped model fits to the Crab's Herschel and Spitzer infrared spectral energy distribution imply the presence of 0.18-0.27 M of dust, corresponding to a gas to dust mass ratio of 26-39. Mixed dust chemistry models can also be accommodated, comprising 0.11-0.13 M of amorphous carbon and 0.39-0.47 M of silicates. Power-law grain size distributions with mass distributions that are weighted toward the largest grain radii are derived, favoring their longer-term survival when they eventually interact with the interstellar medium. The total mass of gas plus dust in the Crab Nebula is 7.2 0.5 M , consistent with a progenitor star mass of ∼9 M .
The discovery with the Herschel Space Observatory of bright far-infrared and submm emission from the ejecta of the core-collapse supernova SN 1987A has been interpreted as indicating the presence of ...some 0.4-0.7 M... of dust. We have constructed radiative transfer models of the ejecta to fit optical to far-infrared observations from the literature at epochs between 615 d and 24 years after the explosion, to determine when and where this unexpectedly large amount of dust formed. We find that the observations by day 1153 are consistent with the presence of 3 x 10... M... of dust. Although this is a larger amount than has previously been considered possible at this epoch, it is still very small compared to the amount present in the remnant after 24 years, and significantly higher dust masses at the earlier epochs are firmly ruled out by the observations, indicating that the majority of the dust must have formed at very late times. By 8515-9200 d after the explosion, 0.6-0.8 M... of dust is present, and dust grains with radii greater than 2 ...m are required to obtain a fit to the observed spectral energy distribution (SED). This suggests that the dust mass increase at late times was caused by accretion on to and coagulation of the dust grains formed at earlier epochs. These findings provide further confirmation that core-collapse supernovae can create large quantities of dust, and indicate that the reason for small dust masses being estimated in many cases is that the vast majority of the dust forms long after most supernovae have been detectable at mid-infrared wavelengths. (ProQuest: ... denotes formulae/symbols omitted.)
Type 2 diabetes mellitus (T2DM) and obesity represent two of the biggest global health challenges of this century and are associated with significant comorbidities and healthcare costs. Although ...multiple factors undoubtedly contribute to the development and progression of DM and obesity, research over the last decade has demonstrated that the microbes that colonize the human gut may play key contributory roles. Gut microbes are now known to codevelop with the human host and are strongly influenced by mode of birth and early diet and nutrition, as well as environmental and other factors including antibiotic exposure. Gut microbes contribute to human health through roles in polysaccharide breakdown, nutrient absorption, inflammatory responses, gut permeability, and bile acid modification. Numerous studies have suggested that disruptions in the relative proportions of gut microbial populations may contribute to weight gain and insulin resistance, including alterations in Gammaproteobacteria and Verrucomicrobia and the ratios of Firmicutes to Bacteroidetes in weight gain and possible alterations in butyrate-producing bacteria such as Faecalibacterium prausnitzii in DM. In addition, it has been shown that the methanogenic Archaea may contribute to altered metabolism and weight gain in the host. However, the majority of studies are performed with stool or colonic samples and may not be representative of the metabolically active small intestine. Studies predominantly in rodent models are beginning to elucidate the mechanisms by which gut microbes contribute to DM and obesity, but much remains to be learned before we can begin to approach targeted treatments.
We report on an analysis of the gas and dust budget in the interstellar medium (ISM) of the Large Magellanic Cloud (LMC). Recent observations from the Spitzer Space Telescope enable us to study the ...mid-infrared dust excess of asymptotic giant branch (AGB) stars in the LMC. This is the first time we can quantitatively assess the gas and dust input from AGB stars over a complete galaxy, fully based on observations. The integrated mass-loss rate over all intermediate and high mass-loss rate carbon-rich AGB candidates in the LMC is 8.5 × 10−3 M⊙ yr−1, up to 2.1 × 10−2 M⊙ yr−1. This number could be increased up to 2.7 × 10−2 M⊙ yr−1 if oxygen-rich stars are included. This is overall consistent with theoretical expectations, considering the star formation rate (SFR) when these low- and intermediate-mass stars where formed, and the initial mass functions. AGB stars are one of the most important gas sources in the LMC, with supernovae (SNe), which produces about 2–4 × 10−2 M⊙ yr−1. At the moment, the SFR exceeds the gas feedback from AGB stars and SNe in the LMC, and the current star formation depends on gas already present in the ISM. This suggests that as the gas in the ISM is exhausted, the SFR will eventually decline in the LMC, unless gas is supplied externally. Our estimates suggest ‘a missing dust-mass problem’ in the LMC, which is similarly found in high-z galaxies: the accumulated dust mass from AGB stars and possibly SNe over the dust lifetime (400–800 Myr) is significant less than the dust mass in the ISM. Another dust source is required, possibly related to star-forming regions.
Diarrhea-predominant irritable bowel syndrome (IBS) is diagnosed through clinical criteria after excluding "organic" conditions, and can be precipitated by acute gastroenteritis. Cytolethal ...distending toxin B (CdtB) is produced by bacteria that cause acute gastroenteritis, and a post-infectious animal model demonstrates that host antibodies to CdtB cross-react with vinculin in the host gut, producing an IBS-like phenotype. Therefore, we assessed circulating anti-CdtB and anti-vinculin antibodies as biomarkers for D-IBS in human subjects. Subjects with D-IBS based on Rome criteria (n=2375) were recruited from a large-scale multicenter clinical trial for D-IBS (TARGET 3). Subjects with inflammatory bowel disease (IBD) (n=142), subjects with celiac disease (n=121), and healthy controls (n=43) were obtained for comparison. Subjects with IBD and celiac disease were recruited based on the presence of intestinal complaints and histologic confirmation of chronic inflammatory changes in the colon or small intestine. Subjects with celiac disease were also required to have an elevated tTG and biopsy. All subjects were aged between 18 and 65 years. Plasma levels of anti-CdtB and anti-vinculin antibodies were determined by ELISA, and compared between groups. Anti-CdtB titers were significantly higher in D-IBS subjects compared to IBD, healthy controls and celiac disease (P<0.001). Anti-vinculin titers were also significantly higher in IBS (P<0.001) compared to the other groups. The area-under-the-receiver operating curves (AUCs) were 0.81 and 0.62 for diagnosis of D-IBS against IBD for anti-CdtB and anti-vinculin, respectively. Both tests were less specific in differentiating IBS from celiac disease. Optimization demonstrated that for anti-CdtB (optical density≥2.80) the specificity, sensitivity and likelihood ratio were 91.6%, 43.7 and 5.2, respectively, and for anti-vinculin (OD≥1.68) were 83.8%, 32.6 and 2.0, respectively. These results confirm that anti-CdtB and anti-vinculin antibodies are elevated in D-IBS compared to non-IBS subjects. These biomarkers may be especially helpful in distinguishing D-IBS from IBD in the workup of chronic diarrhea.
We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 mu m data and improved imaging ...quality at 100 and 160 mu m compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 mu m OI line flux, eliminating the possibility that line contaminations distort the previously estimated dust mass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 mu m flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 + or - 0.1 M sub(middot in circle) of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3 M sub(middot in circle) of amorphous carbon and 0.5 M sub(middot in circle) of silicates, totalling 0.8 M sub(middot in circle) of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies.
High rates of mental health symptoms such as depression, anxiety, and posttraumatic stress disorder (PTSD) have been found in patients hospitalized with traumatic injuries, but little is known about ...these problems in patients hospitalized with acute illnesses. A similarly high prevalence of mental health problems in patients hospitalized with acute illness would have significant public health implications because acute illness and injury are both common, and mental health problems of depression, anxiety, and PTSD are highly debilitating.
In patients admitted after emergency care for Acute Illness (N = 656) or Injury (N = 661) to three hospitals across the United States, symptoms of depression, anxiety, and posttraumatic stress were compared acutely (Acute Stress Disorder) and two months post-admission (PTSD). Patients were ethnically/racially diverse and 54% female. No differences were found between the Acute Illness and Injury groups in levels of any symptoms acutely or two months post-admission. At two months post-admission, at least one symptom type was elevated for 37% of the Acute Illness group and 39% of the Injury group. Within racial/ethnic groups, PTSD symptoms were higher in Black patients with injuries than for Black patients with acute illness. A disproportionate number of Black patients had been assaulted.
This study found comparable levels of mental health sequelae in patients hospitalized after emergency care for acute illness as in patients hospitalized after emergency care for injury. Findings of significantly higher symptoms and interpersonal violence injuries in Black patients with injury suggest that there may be important and actionable differences in mental health sequelae across ethnic/racial identities and/or mechanisms of injury or illness. Routine screening for mental health risk for all patients admitted after emergency care could foster preventive care and reduce ethnic/racial disparities in mental health responses to acute illness or injury.
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