To understand how the multitude of planetary systems that have been discovered come to be, we need to study systems at different evolutionary stages, with different central stars but also in ...different environments. The most challenging environment for planet formation may be the harsh UV radiation field of nearby massive stars which quickly erodes disks by external photo-evaporation. We have observed the AT Pyx system, located in the head of a cometary globule in the Gum Nebula, to search for signs of ongoing planet formation. We used the extreme adaptive optics imager VLT/SPHERE to observe AT Pyx in polarized light as well as total intensity in the J, H and K-band. Additionally we employed VLT/NACO to observe the system in the L-band. We resolve the disk around AT Pyx in scattered light across multiple wavelengths. We find an extended (>126 au) disk, with an intermediate inclination between 35 deg and 42 deg. The disk shows complex sub-structure and we identify 2 and possibly 3 spiral-like features. Depending on the precise geometry of the disk (which we can not unambiguously infer from our data) the disk may be eccentric with an eccentricity of ~0.16 or partially self-shadowed. The spiral features and possible eccentricity are both consistent with signatures of an embedded gas giant planet equal in mass to Jupiter. Our own observations can rule out brown dwarf companions embedded in the resolved disk, but are not sensitive enough to detect gas giants. AT Pyx is the first disk in a cometray globule in the Gum Nebula which is spatially resolved. By comparison with disks in the Orion Nebula Cluster we note that the extension of the disk may be exceptional for this environment if the external UV radiation field is comparable to other cometary globules in the region. The signposts of ongoing planet formation are intriguing and need to be followed up with higher sensitivity.
As part of the Agence Nationale de Recherche Caractérisation des ENvironnements SonorEs urbains (Characterization of urban sound environments) project, a questionnaire was sent in January 2019 to ...households in a 1 km
study area in the city of Lorient, France, to which about 318 responded. The main objective of this questionnaire was to collect information about the inhabitants' perception of the sound environments in their neighborhoods, streets, and dwellings. In the same study area, starting mid-2019, about 70 sensors were continuously positioned, and 15 of them were selected for testing sound source recognition models. The French lockdown due to the COVID-19 crisis occurred during the project, and the opportunity was taken to send a second questionnaire during April 2020. About 31 of the first 318 first survey respondents answered this second questionnaire. This unique longitudinal dataset, both physical and perceptual, allows the undertaking of an analysis from different perspectives of such a period. The analysis reveals the importance of integrating source recognition tools, soundscape observation protocol, in addition to physical level analysis, to accurately describe the changes in the sound environment.
Long term precise radial velocity (RV) monitoring of the nearby star HD206893, as well as anomalies in the system proper motion, have suggested the presence of an additional, inner companion in the ...system. Here we describe the results of a multi-epoch search for the companion responsible for this RV drift and proper motion anomaly using the VLTI/GRAVITY instrument. Utilizing information from ongoing precision RV measurements with the HARPS spectrograph, as well as Gaia host star astrometry, we report a high significance detection of the companion HD206893c over three epochs, with clear evidence for Keplerian orbital motion. Our astrometry with \(\sim\)50-100 \(\mu\)arcsec precision afforded by GRAVITY allows us to derive a dynamical mass of 12.7\(^{+1.2}_{-1.0}\) M\(_{\rm Jup}\) and an orbital separation of 3.53\(^{+0.08}_{-0.06}\) au for HD206893c. Our fits to the orbits of both companions in the system utilize both Gaia astrometry and RVs to also provide a precise dynamical estimate of the previously uncertain mass of the B component, and therefore derive an age of \(155\pm15\) Myr. We find that theoretical atmospheric/evolutionary models incorporating deuterium burning for HD206893c, parameterized by cloudy atmospheres provide a good simultaneous fit to the luminosity of both HD206893B and c. In addition to utilizing long-term RV information, this effort is an early example of a direct imaging discovery of a bona fide exoplanet that was guided in part with Gaia astrometry. Utilizing Gaia astrometry is expected to be one of the primary techniques going forward to identify and characterize additional directly imaged planets. Lastly, this discovery is another example of the power of optical interferometry to directly detect and characterize extrasolar planets where they form at ice-line orbital separations of 2-4\,au.
Microindentation and nanoindentation tests are very useful to assess the micromechanical properties of materials. However, statistical indentation tests require large matrices of indents for ...heterogeneous materials, which can be time-consuming. Given that specific properties of only one phase of interest can be looked for, a novel procedure is proposed to locate indents automatically. The procedure uses an ε–greedy strategy to determine the next indents to perform. The strategy is informed by the nature of predicted indents using unsupervised clustering of the indentation curves and Gaussian Process Classification. The influence of several parameters has been assessed, and the best combination performance has been quantified in the case of the microindentation of a cementitious mortar sample (500 mN) and the nanoindentation of a cement paste (1 mN). The proportion of indents in the phase of interest increased by around 20% in both cases, paving the way for faster indentation experiments.
•ε–greedy strategies can automatically locate the next indents to perform in a phase of interest during indentation.•The technique is used for cementitious materials at the micro- and the nanoscale.•The proportion of indents in the phase of interest can increase by around 20%.•Indentation curves are interpreted by unsupervised learning and Gaussian processes.•The algorithm's parameters can be tuned to increase the global performance.
We initiated a deep-imaging survey of Scorpius-Centaurus A-F stars with predicted warm inner and cold outer belts of debris reminiscent of the architecture of emblematic systems such as HR 8799. We ...present resolved SPHERE images of a narrow ring of debris around the F5-type star HD 141011 that was observed as part of our survey in 2015, 2016, and 2019. The ring extends up to ~1.1" (~141 au) from the star in the IRDIS and IFS data obtained in 2016 and 2019. The disk is not detected in the 2015 data which are of poorer quality. The disks is best reproduced by models of a noneccentric ring centered on the star with an inclination of \(69.1\pm0.9^{\circ}\), a position angle of \(-24.6 \pm 1.7^{\circ}\), and a semimajor axis of \(127.5\pm3.8\) au. The combination of radial velocity and imaging data excludes brown-dwarf (M>13.6 MJup) companions coplanar with the disk from 0.1 to 0.9 au and from 20 au up to 500 au (90% probability). HD 141011 adds to the growing list of debris disks that are resolved in Sco-Cen. It is one of the faintest disks that are resolved from the ground and has a radial extent and fractional width (\(\sim\)12.5%) reminiscent of Fomalhaut. Its moderate inclination and large semimajor axis make it a good target for the James Webb Space Telescope and should allow a deeper search for putative companions shaping the dust distribution.
The employment of 2D perovskites is a promising approach to tackling the stability and voltage issues inherent in perovskite solar cells. It remains unclear, however, whether other perovskites with ...different dimensionalities have the same effect on efficiency and stability. Here, we report the use of quasi-3D azetidinium lead iodide (AzPbI3) as a secondary layer on top of the primary 3D perovskite film that results in significant improvements in the photovoltaic parameters. Remarkably, the utilization of AzPbI3 leads to a new passivation mechanism due to the presence of surface dipoles resulting in a power conversion efficiency (PCE) of 22.4%. The open-circuit voltage obtained is as high as 1.18 V, which is among the highest reported to date for single junction perovskite solar cells, corresponding to a voltage deficit of 0.37 V for a band gap of 1.55 eV.
The dynamical analysis in the original paper was erroneous due to a mismatch in the choice of angular parameters. The calculations had been made by assuming a pole-on (sin i = 0) instead of an ...edge-on sin i = 1 orbit. In this framework, Ω_c-Ωb is just the mutual inclination between the orbital planes of the two planets. We also correct some stellar parameters given in the original paper (log g = +3.83, Fe/Hupdated = -0.26 ).
The dynamical analysis in the original paper was erroneous due to a mismatch in the choice of angular parameters. The calculations had been made by assuming a pole-on (sin i = 0) instead of an ...edge-on sin i = 1 orbit. In this framework, $\Omega_c-\Omega_b$ is just the mutual inclination between the orbital planes of the two planets. We also correct some stellar parameters given in the original paper (log g = +3.83, Fe/Hupdated = -0.26 ).
Abstract
Uranium (U) is a ubiquitous element in the Earth’s crust at ~2 ppm. In anoxic environments, soluble hexavalent uranium (U(VI)) is reduced and immobilized. The underlying reduction mechanism ...is unknown but likely of critical importance to explain the geochemical behavior of U. Here, we tackle the mechanism of reduction of U(VI) by the mixed-valence iron oxide, magnetite. Through high-end spectroscopic and microscopic tools, we demonstrate that the reduction proceeds first through surface-associated U(VI) to form pentavalent U, U(V). U(V) persists on the surface of magnetite and is further reduced to tetravalent UO
2
as nanocrystals (~1–2 nm) with random orientations inside nanowires. Through nanoparticle re-orientation and coalescence, the nanowires collapse into ordered UO
2
nanoclusters. This work provides evidence for a transient U nanowire structure that may have implications for uranium isotope fractionation as well as for the molecular-scale understanding of nuclear waste temporal evolution and the reductive remediation of uranium contamination.
Cancer is common in older patients, who raise specific treatment challenges due to aging-related, organ-specific physiologic changes and the presence in most cases of comorbidities capable of ...affecting treatment tolerance and outcomes. Identifying comorbid conditions and physiologic changes due to aging allows oncologists to better assess the risk/benefit ratio and to adjust the treatment accordingly. Conducting a Comprehensive Geriatric Assessment (CGA) is one approach developed for this purpose. We reviewed the evidence on the usefulness of CGA for assessing health problems and predicting cancer treatment outcomes, functional decline, morbidity, and mortality in older patients with solid malignancies.
We searched Medline for articles published in English between January 1, 2000 and April 14, 2014, and reporting prospective observational or interventional studies of CGA feasibility or effectiveness in patients aged ≥65 years with solid malignancies. We identified studies with at least 100 patients, a multivariate analysis, and assessments of at least five of the following CGA domains: nutrition, cognition, mood, functional status, mobility and falls, polypharmacy, comorbidities, and social environment.
All types of CGA identified a large number of unrecognized health problems capable of interfering with cancer treatment. CGA results influenced 21%-49% of treatment decisions. All CGA domains were associated with chemotoxicity or survival in at least one study. The abnormalities that most often predicted mortality and chemotoxicity were functional impairment, malnutrition, and comorbidities.
The CGA uncovers numerous health problems in elderly patients with cancer and can affect treatment decisions. Functional impairment, malnutrition, and comorbidities are independently associated with chemotoxicity and/or survival. Only three randomized published studies evaluated the effectiveness of CGA-linked interventions. Further research into the effectiveness of the CGA in improving patient outcomes is needed.
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