Search

Context. The possibility of observing spectral features in exoplanet atmospheres with space missions like the James Webb Space Telescope (JWST) and Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) necessitates the accurate modelling of cloud particle opacities. In exoplanet atmospheres, cloud particles can be made from multiple materials and be considerably chemically heterogeneous. Therefore, assumptions on the morphology of cloud particles are required to calculate their opacities. Aims. The aim of this work is to analyse how different approaches to calculate the opacities of heterogeneous cloud particles affect the optical properties of cloud particles and how this may influence the interpretation of data observed by JWST and future missions. Methods. We calculated cloud particle optical properties using seven different mixing treatments: four effective medium theories (EMTs; Bruggeman, Landau-Lifshitz-Looyenga (LLL), Maxwell-Garnett, and Linear), core-shell, and two homogeneous cloud particle approximations. We conducted a parameter study using two-component materials to study the mixing behaviour of 21 commonly considered cloud particle materials for exoplanets. To analyse the impact on observations, we studied the transmission spectra of HATS-6b, WASP-39b, WASP-76b, and WASP-107b. Results. Materials with large refractive indices, like iron-bearing species or carbon, can change the optical properties of cloud particles when they comprise less than 1% of the total particle volume. The mixing treatment of heterogeneous cloud particles also has an observable effect on transmission spectroscopy. Assuming core-shell or homogeneous cloud particles results in less muting of molecular features and retains the cloud spectral features of the individual cloud particle materials. The predicted transit depths for core-shell and homogeneous cloud particle materials are similar for all planets used in this work. If EMTs are used, cloud spectral features are broader and the cloud spectral features of the individual cloud particle materials are not retained. Using LLL leads to fewer molecular features in transmission spectra than when using Bruggeman. [ABSTRACT FROM AUTHOR]

We simulate the geometric albedo spectra of hot Jupiter exoplanets HD 209458 b and WASP-43 b, based on global climate model post-processed with kinetic cloud models. We predict WASP-43 b to be cloudy throughout its dayside, while HD 209458 b has a clear upper atmosphere around the hot subsolar point, largely due to the inclusion of strong optical absorbers TiO and VO in the general circulation model for the latter causes a temperature inversion. In both cases our models find low-geometric albedos – 0.026 for WASP-43 b and 0.028 for HD 209458 b when averaged over the CHaracterizing ExOPlanet Satellite bandpass of |$\sim$| 0.35–1.1  μ m – indicating dark daysides, similar to the low albedos measured by observations. We demonstrate the strong impact of clouds that contain Fe-bearing species on the modelled geometric albedos; without Fe-bearing species forming in the clouds, the albedos of both planets would be much higher (0.518 for WASP-43 b, 1.37 for HD 209458 b). We conclude that a cloudy upper or mid-to-lower atmosphere that contains strongly absorbing Fe-bearing aerosol species, is an alternative to a cloud-free atmosphere in explaining the low-dayside albedos of hot Jupiter atmospheres such as HD 209458 b and WASP-43 b. [ABSTRACT FROM AUTHOR]

Context. Ultra-hot Jupiters present a unique opportunity to understand the physics and chemistry of planets, their atmospheres, and interiors at extreme conditions. WASP-12 b stands out as an archetype of this class of exoplanets, with a close-in orbit around its star that results in intense stellar irradiation and tidal effects. Aims. The goals are to measure the planet's tidal deformation, atmospheric properties, and also to refine its orbital decay rate. Methods. We performed comprehensive analyses of the transits, occultations, and phase curves of WASP-12b by combining new CHEOPS observations with previous TESS and Spitzer data. The planet was modeled as a triaxial ellipsoid parameterized by the second-order fluid Love number of the planet, h2, which quantifies its radial deformation and provides insight into the interior structure. Results. We measured the tidal deformation of WASP-12b and estimated a Love number of h2 = 1.55−0.49+0.45 (at 3.2σ) from its phase curve. We measured occultation depths of 333 ± 24 ppm and 493 ± 29 ppm in the CHEOPS and TESS bands, respectively, while the nightside fluxes are consistent with zero, and also marginal eastward phase offsets. Our modeling of the dayside emission spectrum indicates that CHEOPS and TESS probe similar pressure levels in the atmosphere at a temperature of ~2900 K. We also estimated low geometric albedos of Ag = 0.086 ± 0.017 and Ag = 0.01 ± 0.023 in the CHEOPS and TESS passbands, respectively, suggesting the absence of reflective clouds in the high-temperature dayside of the planet. The CHEOPS occultations do not show strong evidence for variability in the dayside atmosphere of the planet at the median occultation depth precision of 120 ppm attained. Finally, combining the new CHEOPS timings with previous measurements refines the precision of the orbital decay rate by 12% to a value of −30.23 ± 0.82 ms yr−1, resulting in a modified stellar tidal quality factor of Q′★ = 1.70 ± 0.14 × 105. Conclusions. WASP-12 b becomes the second exoplanet, after WASP-103b, for which the Love number has been measured from the effect of tidal deformation in the light curve. However, constraining the core mass fraction of the planet requires measuring h2 with a higher precision. This can be achieved with high signal-to-noise observations with JWST since the phase curve amplitude, and consequently the induced tidal deformation effect, is higher in the infrared. [ABSTRACT FROM AUTHOR]

Context. Measurements of the occultation of an exoplanet at visible wavelengths allow us to determine the reflective properties of a planetary atmosphere. The observed occultation depth can be translated into a geometric albedo. This in turn aids in characterising the structure and composition of an atmosphere by providing additional information on the wavelength-dependent reflective qualities of the aerosols in the atmosphere. Aims. Our aim is to provide a precise measurement of the geometric albedo of the gas giant HD189733b by measuring the occultation depth in the broad optical bandpass of CHEOPS (350-1100 nm). Methods. We analysed 13 observations of the occultation of HD189733b performed by CHEOPS utilising the Python package PyCHEOPS. The resulting occultation depth is then used to infer the geometric albedo accounting for the contribution of thermal emission from the planet. We also aid the analysis by refining the transit parameters combining observations made by the TESS and CHEOPS space telescopes. Results. We report the detection of an 24:7 ± 4:5 ppm occultation in the CHEOPS observations. This occultation depth corresponds to a geometric albedo of 0:076 ± 0:016. Our measurement is consistent with models assuming the atmosphere of the planet to be cloud-free at the scattering level and absorption in the CHEOPS band to be dominated by the resonant Na doublet. Taking into account previous optical-light occultation observations obtained with the Hubble Space Telescope, both measurements combined are consistent with a super-stellar Na elemental abundance in the dayside atmosphere of HD189733b. We further constrain the planetary Bond albedo to between 0.013 and 0.42 at 3 confidence. Conclusions. We find that the reflective properties of the HD189733b dayside atmosphere are consistent with a cloud-free atmosphere having a super-stellar metal content. When compared to an analogous CHEOPS measurement for HD209458b, our data hint at a slightly lower geometric albedo for HD189733b (0:076 ± 0:016) than for HD209458b (0:096 ± 0:016), or a higher atmospheric Na content in the same modelling framework. While our constraint on the Bond albedo is consistent with previously published values, we note that the higher-end values of ~0.4, as derived previously from infrared phase curves, would also require peculiarly high reflectance in the infrared, which again would make it more difficult to disentangle reflected and emitted light in the total observed flux, and therefore to correctly account for reflected light in the interpretation of those phase curves. Lower reported values for the Bond albedos are less affected by this ambiguity. [ABSTRACT FROM AUTHOR]

Lipopolysaccharides (LPS) decorating the cell surface of Gram-negative bacteria exhibit nuanced functionalities linked to their precise structural composition. However, despite their critical role in health and disease, information on the structure and function of LPS from members of the human gut microbiota is still limited. Here, we deciphered the complete structure of the LPS isolated from the human gut bacterium Bacteroides eggerthii 1_2_48FAA. We showed that B. eggerthii 1_2_48FAA produces an R-type LPS (or lipooligosaccharide, LOS) composed of a heterogeneous mixture of tetra- and penta-acylated lipid A species with different degree of phosphorylation, and a compact galactofuranose-containing core oligosaccharide. Using in vitro human cell lines, we showed that B. eggerthii 1_2_48FAA LOS acts as a weak activator of TLR4-mediated signaling. Moreover, we observed that expression of maturation markers CD40, CD80 and CD86 on monocytes-derived dendritic cells upon B. eggerthii 1_2_48FAA LOS exposure was significantly lower compared to pro-inflammatory Escherichia coli LPS. Taken together, these data provide new structural and biological insights into LPS from gut bacteria, underscoring the importance of structural features in modulating host immunity., Competing Interests: Declaration of competing interest All the authors have nothing to declare., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

With an enormous potential in immunology and vaccinology, lipopolysaccharides (LPSs) are among the most extensively studied bacteria-derived molecules. LPS centered studies are countless, and their results reverberate in all areas of the life sciences, including chemistry, biology, genetics, biophysics, and medicine. Most of these research activities are focused on the LPS-induced immune response activation by means of Myeloid Differentiation protein-2/Toll Like Receptor 4 (MD-2/TLR4) complex, which currently is the most largely explored LPS sensing pathway. However, the enormous structural variability of LPS allows interactions with numerous other receptors involved in a wide range of equally important immunological scenarios. In this review, we explore these additional LPS recognition systems, which operate within interconnected signaling cascades, highlighting their role in maintaining physiological homeostasis and their involvement in the development of severe human diseases. Understanding these pathways, their interconnections, and the crosstalk between them and TLR4/MD-2 is essential for guiding the development of pharmacologically active molecules that could specifically modulate the inflammatory response, paving the way to new strategies for combating immune-mediated diseases and resistant infections., (© 2025 The Authors. ChemMedChem published by Wiley-VCH GmbH.)

Transmission spectroscopy has been a workhorse technique used over the past two decades to constrain the physical and chemical properties of exoplanet atmospheres 1-5 . One of its classical key assumptions is that the portion of the atmosphere it probes-the terminator region-is homogeneous. Several works from the past decade, however, have put this into question for highly irradiated, hot (T eq  ≳ 1,000 K) gas giant exoplanets, both empirically 6-10 and through three-dimensional modelling 11-17 . While models have predicted clear differences between the evening (day-to-night) and morning (night-to-day) terminators, direct morning and evening transmission spectra in a wide wavelength range have not been reported for an exoplanet so far. Under the assumption of precise and accurate orbital parameters for the exoplanet WASP-39 b, here we report the detection of inhomogeneous terminators on WASP-39 b, which has allowed us to retrieve its morning and evening transmission spectra in the near-infrared (2-5 μm) using the James Webb Space Telescope. We have observed larger transit depths in the evening, which are, on average, 405 ± 88 ppm larger than the morning ones, and also have qualitatively larger features than the morning spectrum. The spectra are best explained by models in which the evening terminator is hotter than the morning terminator by 17 7 - 57 + 65  K, with both terminators having C/O ratios consistent with solar. General circulation models predict temperature differences broadly consistent with the above value and point towards a cloudy morning terminator and a clearer evening terminator., (© 2024. The Author(s).)

Background: Benign nerve sheath tumors presenting as solitary retroperitoneal masses (RBNSTs) pose a complex diagnostic challenge for multidisciplinary teams regarding differential diagnosis, staging, and treatment planning. This article reviews the role played by different imaging techniques in assessing RBNSTs and elucidates their typical pathological features with a particular emphasis on the correlation between imaging and histological findings. Furthermore, some examples of retroperitoneal tumors that merit consideration in the process of differential diagnosis based on cross-sectional investigations (CSIs) are reported. The correlation between tissue architecture and appearance on imaging can help increase the accuracy of differential diagnosis with other retroperitoneal neoplasms at CSIs., Critical Relevance Statement: This educational review critically examines the correlation between imaging and histological features in solitary retroperitoneal benign nerve sheath tumors, offering valuable insights for improving the accuracy of differential diagnosis in clinical radiology., Key Points: RBNSTs are challenging to diagnose because they lack specific radiological features. Differential diagnosis of RBNSTs from other retroperitoneal neoplasms on imaging is complex. Surgical removal of RBNSTs is recommended for an accurate diagnosis., (© 2024. The Author(s).)

Aim: The incidence of drug-induced sarcoidosis-like reactions (DISR) in patients treated with immune checkpoint inhibitors (ICIs) is rising. We determine the incidence and characteristics of DISR in a metastatic renal cell carcinoma (mRCC) population. Methods: We retrospectively reviewed clinico-radiological data of 83 mRCC patients treated at a single institution with immune-based combinations. Results: 15 patients received immune-doublet (ipilimumab-nivolumab), while 68 patients received other immune-based combinations. Two cases of DISR (2.4%) were evidenced, with enlargement of mediastinal lymph nodes that mimicked disease progression, thus requiring a biopsy which showed histological features of DISR. Conclusion: In our series of the incidence of DISR, radiological and clinical features, are in line with literature. DISR diagnosis is often only radiological, and its occurrence is possibly associated with a better outcome.

Hot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5 μm to 12 μm with the JWST's Mid-Infrared Instrument. The spectra reveal a large day-night temperature contrast (with average brightness temperatures of 1,524 ± 35 K and 863 ± 23 K, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase-curve shape and emission spectra strongly suggest the presence of nightside clouds that become optically thick to thermal emission at pressures greater than ~100 mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Contrary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2 σ upper limit of 1-6 ppm, depending on model assumptions). Our results provide strong evidence that the atmosphere of WASP-43b is shaped by disequilibrium processes and provide new insights into the properties of the planet's nightside clouds. However, the remaining discrepancies between our observations and our predictive atmospheric models emphasize the importance of further exploring the effects of clouds and disequilibrium chemistry in numerical models., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2024.)

Planets grow in rotating disks of dust and gas around forming stars, some of which can subsequently collide in giant impacts after the gas component is removed from the disk 1-3 . Monitoring programmes with the warm Spitzer mission have recorded substantial and rapid changes in mid-infrared output for several stars, interpreted as variations in the surface area of warm, dusty material ejected by planetary-scale collisions and heated by the central star: for example, NGC 2354-ID8 (refs.  4,5 ), HD 166191 (ref.  6 ) and V488 Persei 7 . Here we report combined observations of the young (about 300 million years old), solar-like star ASASSN-21qj: an infrared brightening consistent with a blackbody temperature of 1,000 Kelvin and a luminosity that is 4 percent that of the star lasting for about 1,000 days, partially overlapping in time with a complex and deep, wavelength-dependent optical eclipse that lasted for about 500 days. The optical eclipse started 2.5 years after the infrared brightening, implying an orbital period of at least that duration. These observations are consistent with a collision between two exoplanets of several to tens of Earth masses at 2-16 astronomical units from the central star. Such an impact produces a hot, highly extended post-impact remnant with sufficient luminosity to explain the infrared observations. Transit of the impact debris, sheared by orbital motion into a long cloud, causes the subsequent complex eclipse of the host star., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability 1 . However, no unambiguous photochemical products have been detected in exoplanet atmospheres so far. Recent observations from the JWST Transiting Exoplanet Community Early Release Science Program 2,3 found a spectral absorption feature at 4.05 μm arising from sulfur dioxide (SO 2 ) in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 M J ) gas giant exoplanet orbiting a Sun-like star with an equilibrium temperature of around 1,100 K (ref.  4 ). The most plausible way of generating SO 2 in such an atmosphere is through photochemical processes 5,6 . Here we show that the SO 2 distribution computed by a suite of photochemical models robustly explains the 4.05-μm spectral feature identified by JWST transmission observations 7 with NIRSpec PRISM (2.7σ) 8 and G395H (4.5σ) 9 . SO 2 is produced by successive oxidation of sulfur radicals freed when hydrogen sulfide (H 2 S) is destroyed. The sensitivity of the SO 2 feature to the enrichment of the atmosphere by heavy elements (metallicity) suggests that it can be used as a tracer of atmospheric properties, with WASP-39b exhibiting an inferred metallicity of about 10× solar. We further point out that SO 2 also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations., (© 2023. The Author(s).)

Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining the dominant chemical processes at work and, if in equilibrium, revealing planet formation histories. Transmission spectroscopy (for example, refs. 1,2 ) provides the necessary means by constraining the abundances of oxygen- and carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution and high precision, which, together, are not achievable with previous observatories. Now that JWST has commenced science operations, we are able to observe exoplanets at previously uncharted wavelengths and spectral resolutions. Here we report time-series observations of the transiting exoplanet WASP-39b using JWST's Near InfraRed Camera (NIRCam). The long-wavelength spectroscopic and short-wavelength photometric light curves span 2.0-4.0 micrometres, exhibit minimal systematics and reveal well defined molecular absorption features in the planet's spectrum. Specifically, we detect gaseous water in the atmosphere and place an upper limit on the abundance of methane. The otherwise prominent carbon dioxide feature at 2.8 micrometres is largely masked by water. The best-fit chemical equilibrium models favour an atmospheric metallicity of 1-100-times solar (that is, an enrichment of elements heavier than helium relative to the Sun) and a substellar C/O ratio. The inferred high metallicity and low C/O ratio may indicate significant accretion of solid materials during planet formation (for example, refs. 3,4 , ) or disequilibrium processes in the upper atmosphere (for example, refs. 5,6 )., (© 2023. The Author(s).)

Background: Interventions involving exercise appear to have positive effects, both for people with dementia and for their carers. Quality of life and well-being are especially important outcomes. This study investigated how a sports and exercise group for people with dementia and their carers could contribute to the well-being of those attending the group., Methods: The study was a qualitative investigation, comprising semi-structured interviews, a focus group and observations. Participants included people with dementia and carers attending the group sessions, as well as staff providing the programme. The group sessions were provided weekly by the charitable trust of a leading sports venue. Data were analysed using thematic analysis., Results: A total of 16 participants were interviewed, including four people with dementia, eight carers, and four members of staff. Five main themes were identified: "Support to keep active and engaged is highly valued by people with dementia and carers"; "The challenges of being a carer are significant but sharing the experience really helps"; "People with dementia can have flourishing social lives"; "The group helps to maintain identity despite physical and role changes"; and "There are practical aspects of the group that make it appealing"., Discussion: People with dementia enjoy physical activity and experience the benefits of it. The sports and exercise group had an important role in providing access to activities that people with dementia and their carers value and enjoy, but would be difficult to undertake without a facilitated and safe environment. The group benefited the well-being of both people with dementia and carers in various ways, with peer support being of particular importance for carers., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Chadwick, Hussain, Carone, Yates and Dening.)