16 research outputs found

    Non-Local thermal equilibrium spectra of atmospheric molecules for exoplanets

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    Here we present a study of non-LTE effects on the exoplanetary spectra of a collection of molecules which are key in the investigation of exoplanet atmospheres: water, methane, carbon monoxide and titanium oxide. These molecules are chosen as examples of different spectral ranges (IR and UV), molecular types (diatomics and polyatomics) and spectral types (electronic and ro-vibrational); the importance of different vibrational bands in forming distinct non-LTE spectral features are investigated. Most notably, such key spectral signatures for distinguishing between the LTE and non-LTE cases include: for CH4 the 3.15 μ\mum band region; for H2O the 2.0 μ\mum and 2.7 μ\mum band regions; for TiO, a strong variation in intensity in the bands between 0.5 and 0.75 μ\mum; and a sole CO signature between 5 and 6 μ\mum. The analysis is based on the ExoMol cross sections and takes advantage of the extensive vibrational assignment of these molecular line lists in the ExoMol database. We examine LTE and non-LTE cross sections under conditions consistent with those on WASP-12b and WASP-76b using the empirically motivated bi-temperature Treanor model. In addition, we make a simplistic forward model simulation of transmission spectra for H2O in the atmosphere of WASP-12b using the TauREx 3 atmospheric modelling code

    Constraining the atmospheric elements in hot Jupiters with Ariel

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    One of the main objectives of the European Space Agency’s Ariel telescope (launch 2029) is to understand the formation and evolution processes of a large sample of planets in our Galaxy. Important indicators of such processes in giant planets are the elemental compositions of their atmospheres. Here we investigate the capability of Ariel to constrain four key atmospheric markers: metallicity, C/O, S/O, and N/O, for three well-known, representative hot-Jupiter atmospheres observed with transit spectroscopy, i.e. HD 209458b, HD 189733b, and WASP-121b. We have performed retrieval simulations for these targets to verify how the planetary formation markers listed above would be recovered by Ariel when observed as part of the Ariel Tier 3 survey. We have considered eight simplified different atmospheric scenarios with a cloud-free isothermal atmosphere. Additionally, extra cases were tested to illustrate the effect of C/O and metallicity in recovering the N/O. From our retrieval results, we conclude that Ariel is able to recover the majority of planetary formation markers. The contributions from CO and CO2 are dominant for the C/O in the solar scenario. In a C-rich case, C2H2, HCN, and CH4 may provide additional spectral signatures that can be captured by Ariel. In our simulations, H2S is the main tracer for the S/O in hot-Jupiter atmospheres. In the super-solar metallicity cases and the cases with C/O > 1, the increased abundance of HCN is easily detectable and the main contributor to N/O, while other N-bearing species contribute little to the N/O in the investigated atmospheres

    ExoMol line lists – LI. Molecular line lists for lithium hydroxide (LiOH)

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    New molecular line lists for lithium hydroxide (6Li16O1H and 7Li16O1H isotopologues) covering wavelengths λ > 1 μ m (0–10 000 cm−1 range) are presented. Each line list contains around 300 million transitions between rotation–vibration energy levels with total angular momentum up to J = 95, applicable for temperatures up to T ≈ 3500 K. Line list calculations were based on a previously published, high-level ab initio potential energy surface and a newly computed dipole moment surface of the ground X~1Σ+ electronic state. Lithium-containing molecules are important in a variety of stellar objects and there is potential for LiOH to be observed in the atmospheres of exoplanets. Transit spectra are simulated using the rocky super-Earth 55 Cancri e as an example with two different atmospheric scenarios including LiOH. This work provides the first, comprehensive line lists of LiOH to facilitate its future molecular detection. The OYT7 line lists along with the associated temperature- and pressure-dependent molecular opacities can be downloaded from the ExoMol database at www.exomol.com and the CDS astronomical database

    Vitamin D and cause-specific vascular disease and mortality:a Mendelian randomisation study involving 99,012 Chinese and 106,911 European adults

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    Pan-cancer analysis of whole genomes

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    Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

    Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

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    Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

    Ultralight vector dark matter search using data from the KAGRA O3GK run

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    Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

    Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M&gt;70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0&lt;e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

    Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

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    Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

    Adiposity and risk of ischaemic and haemorrhagic stroke in 0·5 million Chinese men and women: a prospective cohort study

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    Summary: Background: China has high stroke rates despite the population being relatively lean. Uncertainty persists about the relevance of adiposity to risk of stroke types. We aimed to assess the associations of adiposity with incidence of stroke types and effect mediation by blood pressure in Chinese men and women. Methods: The China Kadoorie Biobank enrolled 512 891 adults aged 30–79 years from ten areas (five urban and five rural) during 2004–08. During a median 9 years (IQR 8–10) of follow-up, 32 448 strokes (about 90% confirmed by neuroimaging) were recorded among 489 301 participants without previous cardiovascular disease. Cox regression analysis was used to produce adjusted hazard ratios (HRs) for ischaemic stroke (n=25 210) and intracerebral haemorrhage (n=5380) associated with adiposity. Findings: Mean baseline body-mass index (BMI) was 23·6 kg/m2 (SD 3·2), and 331 723 (67·8%) participants had a BMI of less than 25 kg/m2. Throughout the range examined (mean 17·1 kg/m2 [SD 0·9] to 31·7 kg/m2 [2·0]), each 5 kg/m2 higher BMI was associated with 8·3 mm Hg (SE 0·04) higher systolic blood pressure. BMI was positively associated with ischaemic stroke, with an HR of 1·30 (95% CI 1·28–1·33 per 5 kg/m2 higher BMI), which was generally consistent with that predicted by equivalent differences in systolic blood pressure (1·25 [1·24–1·26]). The HR for intracerebral haemorrhage (1·11 [1·07–1·16] per 5 kg/m2 higher BMI) was less extreme, and much weaker than that predicted by the corresponding difference in systolic blood pressure (1·48 [1·46–1·50]). Other adiposity measures showed similar associations with stroke types. After adjustment for usual systolic blood pressure, the positive associations with ischaemic stroke were attenuated (1·05 [1·03–1·07] per 5 kg/m2 higher BMI); for intracerebral haemorrhage, they were reversed (0·73 [0·70–0·77]). High adiposity (BMI >23 kg/m2) accounted for 14·7% of total stroke (16·5% of ischaemic stroke and 6·7% of intracerebral haemorrhage). Interpretation: In Chinese adults, adiposity was strongly positively associated with ischaemic stroke, chiefly through its effect on blood pressure. For intracerebral haemorrhage, leanness, either per se or through some other factor (or factors), might increase risk, offsetting the protective effects of lower blood pressure. Funding: UK Wellcome Trust, UK Medical Research Council, British Heart Foundation, Cancer Research UK, Kadoorie Charitable Foundation, Chinese Ministry of Science and Technology, Chinese National Natural Science Foundation
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