Starburst-driven Starbursts in the Heart of Ultraluminous Infrared Galaxies

There is increasing evidence for the presence of blue super star clusters in the central regions of ultraluminous infrared galaxies like Arp 220. Ultraluminous galaxies are thought to be triggered by galaxy mergers, and it has often been argued that these super star clusters may form during violent collisions between gas clouds in the final phase of the mergers. We now investigate another set of models which differ from previous ones in that the formation of the super star clusters is linked directly to the very intense starburst occurring at the very center of the galaxy. Firstly we show that a scenario in which the super star clusters form in material compressed by shock waves originating from the central starburst is implausible because the objects so produced are much smaller than the observed star clusters in Arp 220. We then investigate a scenario (based on the Shlosman-Noguchi model) in which the infalling dense gas disk is unstable gravitationally and collapses to form massive gaseous clumps. Since these clumps are exposed to the external high pressure driven by the superwind (a blast wave driven by a collective effect of a large number of supernovae in the very core of the galaxy), they can collapse and then massive star formation may be induced in them. The objects produced in this kind of collapse have properties consistent with those of the observed super star clusters in the center of Arp 220.Comment: 13 pages, 1 figure, ApJ (Letters) in pres

A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study

Introduction: The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures. Methods: In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged ≥18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025. Findings: Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5·0 months (IQR 4·2–6·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0·0001) and independently associated with COVID-19 status (odds ratio [OR] 2·9 [95% CI 1·5–5·8]; padjusted=0·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0·0001; parenchymal abnormalities), brain abnormalities (p<0·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4–10]; mean age of 59·8 years [SD 11·7] with multiorgan abnormalities vs mean age of 52·8 years [11·9] without multiorgan abnormalities; p<0·0001), more likely to have three or more comorbidities (OR 2·47 [1·32–4·82]; padjusted=0·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3·55 [1·23–11·88]; padjusted=0·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation. Interpretation: After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification

A polymorphism that reduces RANTES expression is associated with protection from death in HIV-seropositive Ugandans with advanced disease.

We investigated the effect of RANTES polymorphisms on human immunodeficiency virus type 1 (HIV-1) disease progression in an urban population of Uganda. HIV-positive individuals homozygous for the INT1.1C polymorphism, which had been associated previously with low RANTES expression, were less likely to die than were those with other genotypes (hazard ratio, 0.53 [95% confidence interval, 0.33-0.83]; P=.007). This report of a non-human leukocyte antigen genetic association with HIV-1 and/or acquired immunodeficiency syndrome disease progression in an African population reveals a genetic effect different from that reported elsewhere for African Americans and may impact therapeutic strategies targeting the RANTES pathway in HIV infection

Cytokine responses and progression to active tuberculosis in HIV-1-infected Ugandans: a prospective study.

Identifying correlates of immunity or susceptibility to disease promotes understanding of pathogenesis and development of diagnostic tools, treatments, and vaccines. There is evidence that type 1 cytokine responses are associated with protection against tuberculosis, and suppression of type 1, or switching to type 2 responses, with susceptibility, but this has not been studied prospectively. We studied a cohort of 631 HIV-1-infected Ugandan adults. At enrollment we performed whole blood cultures for type 1 (interferon [IFN]-gamma, interleukin [IL]-2) and type 2/immunosuppressive (IL-5, IL-10) responses to mycobacterial antigens (purified protein derivative [PPD] and culture filtrate proteins [CFP]). The incidence of tuberculosis was not associated with IFN-gamma responses, but was higher among participants with IL-2 responses (adjusted rate ratios [RR]: PPD 3.48; CFP 3.99; P < 0.001). For tuberculin skin test-positive participants, high incidence was also associated with an IL-10 response to PPD (adjusted RR 6.24, P = 0.03); for those with a BCG scar, high incidence was associated with positive IL-5 responses (adjusted RRs: PPD 3.64, P = 0.006; CFP 3.44, P = 0.04). The association with IL-2 production may reflect a response to tuberculous infection or to activating disease; the associations with IL-10 and IL-5 are in keeping with the expected role of immunosuppressive or type 2 cytokines

Alcohol sensitivity, alcohol use and hypertension in an older Chinese population: the Guangzhou Biobank Cohort Study

Although the J-shaped association between alcohol consumption and blood pressure (BP) is well known, the effect of alcohol sensitivity on this relationship is less clear. We studied the association of alcohol sensitivity and alcohol use with BP and hypertension. This cross-sectional analysis included 19335 older participants from the Guangzhou Biobank Cohort Study recruited from 2003 to 2006, using clinically measured BP and self-reported alcohol use and alcohol sensitivity. Alcohol use was rare in women, in whom light-to-moderate drinkers (<140 g ethanol per week) without alcohol sensitivity had lower systolic and diastolic BPs (mean difference 5.3 (95% CI 3.8-6.9) mmHg and 1.9 (1.1-2.7) mm Hg, respectively) and a reduced risk of hypertension (0.62 (0.53-0.72)) relative to never drinkers. Similarly, excessive drinkers (≥140g ethanol per week) without alcohol sensitivity had a significantly higher systolic and diastolic BP and risk of hypertension than did nondrinkers (mean difference 5.1 (2.8-7.4) mm Hg, 2.7 (1.5-4.0) mm Hg and 34% (8-66%), respectively, for men). These differences were even greater for men with alcohol sensitivity (mean differences 12.0 (8.9-15.2) mm Hg, 6.2 (4.5-7.9) mmHg and 95% CI (46-159%), respectively). Alcohol sensitivity and alcohol use were both associated with elevated BP and risk of hypertension in an older Chinese population. Alcohol sensitivity may aggravate the effect of drinking on BP. Limiting alcohol use to two drinks per day for men and one drink a day for women may be suitable for East Asians. Reduction of alcohol consumption should be an important public health target.link_to_subscribed_fulltex