1,072 research outputs found
WASP-39b: exo-Saturn with patchy cloud composition, moderate metallicity, and underdepleted S/O
WASP-39b is one of the first extrasolar giant gas planets that has been
observed within the JWST ERS program. Fundamental properties that may enable
the link to exoplanet formation differ amongst retrieval methods, for example
metallicity and mineral ratios.
In this work, the formation of clouds in the atmosphere of WASP-39b is
explored to investigate how inhomogeneous cloud properties (particle sizes,
material composition, opacity) may be for this intermediately warm gaseous
exoplanet. WASP-39b's atmosphere has a comparable day-night temperature median
with sufficiently low temperatures that clouds may form globally. The presence
of clouds on WASP-39b can explain observations without resorting to a high (>
100x solar) metallicity atmosphere for a reduced vertical mixing efficiency.
The assessment of mineral ratios shows an under-depletion of S/O due to
condensation compared to C/O, Mg/O, Si/O, Fe/O ratios. Vertical patchiness due
to heterogeneous cloud composition challenges simple cloud models. An equal
mixture of silicates and metal oxides is expected to characterise the cloud
top. Further, optical properties of Fe and Mg silicates in the mid-infrared
differ significantly which will impact the interpretation of JWST observations.
We conclude that WASP-39b's atmosphere contains clouds and the underdepletion
of S/O by atmospheric condensation processes suggest the use of sulphur gas
species as a possible link to primordial element abundances. Over-simplified
cloud models do not capture the complex nature of mixed-condensate clouds in
exoplanet atmospheres. The clouds in the observable upper atmosphere of
WASP-39b are a mixture of different silicates and metal oxides. The use of
constant particles sizes and/or one-material cloud particles alone to interpret
spectra may not be sufficient to capture the full complexity available through
JWST observations.Comment: 21 pages, 18 figures, submitted to A&A on 22. November 2022, in
review since 8. December 202
Helminth Infection is Associated with Dampened Cytokine Responses to Viral and Bacterial Stimulations in Tsimane Forager-Horticulturalists
Background
Soil-transmitted helminths (STHs) and humans share long co-evolutionary histories over which STHs have evolved strategies to permit their persistence by downregulating host immunity. Understanding the interactions between STHs and other pathogens can inform our understanding of human evolution and contemporary disease patterns. Methodology
We worked with Tsimane forager-horticulturalists in the Bolivian Amazon, where STHs are prevalent. We tested whether STHs and eosinophil levelsâlikely indicative of infection in this populationâare associated with dampened immune responses to in vitro stimulation with H1N1 and lipopolysaccharide (LPS) antigens. Whole blood samples (nâ=â179) were treated with H1N1 vaccine and LPS and assayed for 13 cytokines (INF-Îł, IL-1ÎČ, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, GM-CSF and TNF-É). We evaluated how STHs and eosinophil levels affected cytokine responses and T helper (Th) 1 and Th2-cytokine suite responses to stimulation. Results
Infection with Ascaris lumbricoides was significantly (Pââ€â0.05) associated with lower response of some cytokines to H1N1 and LPS in women. Eosinophils were significantly negatively associated with some cytokine responses to H1N1 and LPS, with the strongest effects in women, and associated with a reduced Th1- and Th2-cytokine response to H1N1 and LPS in women and men. Conclusions and implications
Consistent with the âold friendsâ and hygiene hypotheses, we find that STHs were associated with dampened cytokine responses to certain viral and bacterial antigens. This suggests that STH infections may play an essential role in immune response regulation and that the lack of STH immune priming in industrialized populations may increase the risk of over-reactive immunity.
Lay Summary: Indicators of helminth infection were associated with dampened cytokine immune responses to in vitro stimulation with viral and bacterial antigens in Tsimane forager-horticulturalists in the Bolivian Amazon, consistent with the âold friendsâ and hygiene hypotheses
Polarization and Interference Effects in Ionization of Li by Ion Impact
We present initial-state selective fully differential cross sections for ionization of lithium by 24 MeV O8+ impact. The data for ionization from the 2s and 2p states look qualitatively different from each other and from 1s ionization of He. For ionization from the 2p state, to which in our study the mL=-1 substate predominantly contributes, we observe orientational dichroism and for 2s ionization pronounced interference which we trace back to the nodal structure of the initial-state wave function
New parton distributions in fixed flavour factorization scheme from recent deep-inelastic-scattering data
We present our QCD analysis of the proton structure function
to determine the parton distributions at the next-to-leading order (NLO). The
heavy quark contributions to , with = , have been
included in the framework of the `fixed flavour number scheme' (FFNS). The
results obtained in the FFNS are compared with available results such as the
general-mass variable-flavour-number scheme (GM-VFNS) and other prescriptions
used in global fits of PDFs. In the present QCD analysis, we use a wide range
of the inclusive neutral-current deep-inelastic-scattering (NC DIS) data,
including the most recent data for charm , bottom , longitudinal
structure functions and also the reduced DIS cross sections
from HERA experiments. The most recent HERMES data for
proton and deuteron structure functions are also added. We take into account
ZEUS neutral current DIS inclusive jet cross section data from HERA
together with the recent Tevatron Run-II inclusive jet cross section data from
CDF and D{\O}. The impact of these recent DIS data on the PDFs extracted from
the global fits are studied. We present two families of PDFs, {\tt KKT12} and
{\tt KKT12C}, without and with HERA `combined' data sets on DIS. We
find these are in good agreement with the available theoretical models.Comment: 23 pages, 26 figures and 4 tables. V3: Only few comments and
references added in the replaced version, results unchanged. Code can be
found at http://particles.ipm.ir/links/QCD.ht
Ion-Lithium Collision Dynamics Studied with a Laser-Cooled In-Ring Target
We present a novel experimental tool allowing for kinematically complete studies of break-up processes of laser-cooled atoms. This apparatus, the \u27MOTReMi,\u27 is a combination of a magneto-optical trap (MOT) and a reaction microscope (ReMi). Operated in an ion-storage ring, the new setup enables us to study the dynamics in swift ion-atom collisions on an unprecedented level of precision and detail. In the inaugural experiment on collisions with 1.5MeV/amu O8 +-Li the pure ionization of the valence electron as well as the ionization-excitation of the lithium target was investigated
Clinical prediction models to support the diagnosis of asthma in primary care: a systematic review protocol
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Open Science principles for accelerating trait-based science across the Tree of Life.
Synthesizing trait observations and knowledge across the Tree of Life remains a grand challenge for biodiversity science. Species traits are widely used in ecological and evolutionary science, and new data and methods have proliferated rapidly. Yet accessing and integrating disparate data sources remains a considerable challenge, slowing progress toward a global synthesis to integrate trait data across organisms. Trait science needs a vision for achieving global integration across all organisms. Here, we outline how the adoption of key Open Science principles-open data, open source and open methods-is transforming trait science, increasing transparency, democratizing access and accelerating global synthesis. To enhance widespread adoption of these principles, we introduce the Open Traits Network (OTN), a global, decentralized community welcoming all researchers and institutions pursuing the collaborative goal of standardizing and integrating trait data across organisms. We demonstrate how adherence to Open Science principles is key to the OTN community and outline five activities that can accelerate the synthesis of trait data across the Tree of Life, thereby facilitating rapid advances to address scientific inquiries and environmental issues. Lessons learned along the path to a global synthesis of trait data will provide a framework for addressing similarly complex data science and informatics challenges
The N2K Consortium. IV. New temperatures and metallicities for 100,000+ FGK dwarfs
We have created a framework to facilitate the construction of specialized
target lists for radial velocity surveys that are biased toward stars that (1)
possess planets and (2) are easiest to observe with current detection
techniques. We use a procedure that uniformly estimates fundamental stellar
properties of Tycho 2 stars, with errors, using spline functions of broadband
photometry and proper motion found in Hipparcos/Tycho 2 and 2MASS. We provide
estimates of temperature and distance for 2.4 million Tycho 2 stars that lack
trigonometric distances. For stars that appear to be FGK dwarfs according to
estimated temperature and absolute magnitude, we also derive [Fe/H] and
identify unresolved binary systems with mass ratios between 1.25 and 3. Our
spline function models are trained on the unique Valenti & Fischer (2005) set,
composed of 1000 dwarfs with precise stellar parameters estimated from HIRES
spectroscopy. For FGK dwarfs with V photometric error less than 0.05
magnitudes, or V < 9, our temperature model gives a one-sigma error of
+58.7/-65.9 K and our metallicity model gives a one-sigma error of +0.13/-0.14
dex. Our estimates of distance and spectral type enable us to isolate 354,822
Tycho 2 dwarfs, 321,996 of which are absent from Hipparcos, with giant and
subgiant contamination at 2.6% and 7.2%, respectively. 2,500 of these FGK
dwarfs are bright (V 0.2). Our metallicity
estimates have been used to identify targets for N2K (Fischer et al. 2005), a
large-scale radial velocity search for Hot Jupiters, which has published the
detection of 4 Hot Jupiters with one transit. The broadband filtering outlined
here is the first screening tier for N2K; the second tier is a low-resolution
spectroscopy program headed by S.E. Robinson (astro-ph/0510150).Comment: 32 pages, 8 figures, accepted by ApJS in October 2005. Data files
temporarily stored at http://www.ucolick.org/~ammons/tycho_parameter
Measurement of the production of a W boson in association with a charm quark in pp collisions at âs = 7 TeV with the ATLAS detector
The production of a W boson in association with a single charm quark is studied using 4.6 fbâ1 of pp collision data at sâ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26â0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio Ï(W + +cÂŻÂŻ)/Ï(W â + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the sâsÂŻÂŻÂŻ quark asymmetry
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