148 research outputs found
Constraints on the mass and atmospheric composition and evolution of the low-density young planet DS Tuc A b
We performed a radial velocity (RV) monitoring of the 40 Myr old star DS Tuc
A with HARPS at the ESO-3.6m to determine the planetary mass of its 8.14-days
planet, first revealed by TESS. We also observed two planetary transits with
HARPS and ESPRESSO at ESO-VLT, to measure the Rossiter-McLaughlin (RM) effect
and characterise the planetary atmosphere. We measured the high-energy emission
of the host with XMM observations to investigate models for atmospheric
evaporation. We employed Gaussian Processes (GP) regression to model the high
level of the stellar activity, which is more than 40 times larger than the
expected RV planetary signal. We extracted the transmission spectrum of DS Tuc
A b from the ESPRESSO data and searched for atmospheric elements/molecules
either by single-line retrieval and by performing cross-correlation with a set
of theoretical templates. Through a set of simulations, we evaluated different
scenarios for the atmospheric photo-evaporation of the planet induced by the
strong XUV stellar irradiation. While the stellar activity prevented us from
obtaining a clear detection of the planetary signal from the RVs, we set a
robust mass upper limit of 14.4 M_e for DS Tuc A b. We also confirm that the
planetary system is almost (but not perfectly) aligned. The strong level of
stellar activity hampers the detection of any atmospheric compounds, in line
with other studies presented in the literature. The expected evolution of DS
Tuc A b from our grid of models indicates that the planetary radius after the
photo-evaporation phase will fall within the Fulton gap. The comparison of the
available parameters of known young transiting planets with the distribution of
their mature counterpart confirms that the former are characterised by a low
density, with DS Tuc A b being one of the less dense.Comment: 24 pages, 19 figures, Accepted for publication on Astronomy and
Astrophysic
Exploring the potential of using a text-based game to inform simulation models of risky migration decisions
Background:
In this paper, we explore the potential of games to collect empirical data for informing agent-based simulation models of migration. To examine the usefulness of game-based approaches, we conducted a simple, yet carefully designed psychological experiment.
Methods:
In a preregistered study, we used a novel, immersive experimental setting to investigate the risky migration decisions made by migrants and non-migrants. Participants (284 migrants and 284 non-migrants) played a choice-based interactive fiction game—a fully text-based game where players progress by selecting from a list of possible actions—that involved making three risky migration decisions. In one condition, participants were shown a non-linear progress bar and explicit acknowledgements of the choices they made to promote perceived agency: the feeling that one’s actions have a non-trivial impact on the game. In the other condition, the progress bar was linear, and the explicit acknowledgements were omitted.
Results:
Our experimental manipulation was successful; participants in the former condition self-reported higher perceived agency than participants in the latter condition, as did migrants compared to non-migrants. Nevertheless, condition and migrant status did not meaningfully affect the risky migration decisions participants made in the game.
Conclusion:
These findings indicate that the results of generic studies on risky migration decisions conducted on non-migrants can potentially inform simulation models of migration. However, these findings were obtained from a single experiment, and thus warrant replication and further research before definitive conclusions can be drawn. Furthermore, a simple text-based game may be too superficial to allow deep insights into the idiosyncrasies of migration decision-making. This suggests a possible trade-off between clear interpretability of the results and the usefulness for informing simulation models of complex social processes, such as migration
Stereodifferentiation in the formation and decay of the encounter complex in bimolecular electron transfer with photoactivated acceptors
Experimental evidence has been obtained for the involvement of encounter complexes between both enantiomers of a π,π* triplet excited ketone and a chiral phenol or indole. Determination of the pre-equilibrium constants (KEC) and the intrinsic decay rate constants (kd) indicates a significant stereodifferentiation in both steps of the quenching process.Perez Prieto, Julia, [email protected] ; Galian, Raquel Eugenia, [email protected] ; Morant Miñana, Maria Carmen, [email protected]
ARES. III. Unveiling the Two Faces of KELT-7 b with HST WFC3*
We present the analysis of the hot-Jupiter KELT-7 b using transmission and emission spectroscopy from the Hubble Space Telescope, both taken with the Wide Field Camera 3. Our study uncovers a rich transmission spectrum that is consistent with a cloud-free atmosphere and suggests the presence of H_{2}O and H^{−}. In contrast, the extracted emission spectrum does not contain strong absorption features and, although it is not consistent with a simple blackbody, it can be explained by a varying temperature–pressure profile, collision induced absorption, and H^{-}. KELT-7 b had also been studied with other space-based instruments and we explore the effects of introducing these additional data sets. Further observations with Hubble, or the next generation of space-based telescopes, are needed to allow for the optical opacity source in transmission to be confirmed and for molecular features to be disentangled in emission
Triplet exciplexes as energy transfer photosensitisers
Experimental evidence is provided for the occurrence of triplet–triplet energy transfer from benzoylthiophene–indole exciplexes to naphthalenes with a remarkable stereodifferentiation; chiral recognition is also observed in the decay of the generated naphthalene triplets.Perez Prieto, Julia, [email protected] ; Galian, Raquel Eugenia, [email protected] ; Morant Miñana, Maria Carmen, [email protected]
45S rDNA external transcribed spacer organization reveals new phylogenetic relationships in Avena genus
Research ArticleThe genus Avena comprises four distinct genomes organized in diploid (AA or CC), tetraploid
(AABB or AACC) and hexaploid species (AACCDD), constituting an interesting model
for phylogenetic analysis. The aim of this work was to characterize 45S rDNA intergenic
spacer (IGS) variability in distinct species representative of Avena genome diversity±A.
strigosa (AA), A. ventricosa (CvCv), A. eriantha (CpCp), A. barbata (AABB), A. murphyi
(AACC), A. sativa (AACCDD) and A. sterilis (AACCDD) through the assessment of the 5'
external transcribed spacer (5'-ETS), a promising IGS region for phylogenetic studies poorly
studied in Avena genus. In this work, IGS length polymorphisms were detected mainly due
to distinct 5'-ETS sequence types resulting from major differences in the number and organization
of repeated motifs. Although species with A genome revealed a 5'-ETS organization
(A-organization) similar to the one previously described in A. sativa, a distinct organization
was unraveled in C genome diploid species (C-organization). Interestingly, such new organization
presents a higher similarity with other Poaceae species than A-genome sequences,
supporting the hypothesis of C-genome being the ancestral Avena genome. Additionally,
polyploid species with both genomes mainly retain the A-genome 5'-ETS organization, confirming
the preferential elimination of C-genome sequences in Avena polyploid species.
Moreover, 5'-ETS sequences phylogenetic analysis consistently clustered the species studied
according to ploidy and genomic constitution supporting the use of ribosomal genes to
highlight Avena species evolutive pathways.info:eu-repo/semantics/publishedVersio
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