471 research outputs found
The ESPARR cohort: The future of serious injured aged 16years and over (M.AIS3+) with a traumatic brain injury (TBI) 3years after the crash
Simulated performance of the molecular mapping for young giant exoplanets with the Medium Resolution Spectrometer of JWST/MIRI
Young giant planets are the best targets for characterization with direct
imaging. The Medium Resolution Spectrometer (MRS) of the Mid-Infrared
Instrument (MIRI) of the recently launched James Webb Space Telescope (JWST)
will give access to the first spectroscopic data for direct imaging above 5
m with unprecedented sensitivity at a spectral resolution up to 3700. This
will provide a valuable complement to near-infrared data from ground-based
instruments for characterizing these objects. We aim to evaluate the
performance of MIRI/MRS to detect molecules in the atmosphere of exoplanets and
to constrain atmospheric parameters using Exo-REM atmospheric models. The
molecular mapping technique, based on cross-correlation with synthetic models,
has been introduced recently. This promising detection and characterization
method is tested on simulated MIRI/MRS data. Directly imaged planets can be
detected with MIRI/MRS, and we are able to detect molecules (HO, CO,
NH, CH, HCN, PH, CO) at various angular separation depending on
the strength of the molecular features and brightness of the target. We find
that the stellar spectral type has a weak impact on the detection level. This
method is globally most efficient for planets with temperatures below 1500 K,
for bright targets and angular separation greater than 1. Our parametric
study allows us to anticipate the ability to characterize planets that would be
detected in the future. The MIRI/MRS will give access to molecular species not
yet detected in exoplanetary atmospheres. The detection of molecules as
indicators of the temperature of the planets will make it possible to
discriminate between the various hypotheses of the preceding studies, and the
derived molecular abundance ratios should bring new constraints on planetary
formation scenarios.Comment: 25 pages, 13 figure
Évolution de la qualité de vie après un traumatisme crânien par accident de la route : un suivi à cinq ans de la cohorte ESPARR
Continua com: Info Ajuntament+Sostenible : notícies de l'Ajuntament+sostenibl
Methane storms as a driver of Titan's dune orientation
Titan's equatorial regions are covered by eastward propagating linear dunes.
This direction is opposite to mean surface winds simulated by Global Climate
Models (GCMs), which are oriented westward at these latitudes, similar to trade
winds on Earth. Different hypotheses have been proposed to address this
apparent contradiction, involving Saturn's gravitational tides, large scale
topography or wind statistics, but none of them can explain a global eastward
dune propagation in the equatorial band. Here we analyse the impact of
equinoctial tropical methane storms developing in the superrotating atmosphere
(i.e. the eastward winds at high altitude) on Titan's dune orientation. Using
mesoscale simulations of convective methane clouds with a GCM wind profile
featuring superrotation, we show that Titan's storms should produce fast
eastward gust fronts above the surface. Such gusts dominate the aeolian
transport, allowing dunes to extend eastward. This analysis therefore suggests
a coupling between superrotation, tropical methane storms and dune formation on
Titan. Furthermore, together with GCM predictions and analogies to some
terrestrial dune fields, this work provides a general framework explaining
several major features of Titan's dunes: linear shape, eastward propagation and
poleward divergence, and implies an equatorial origin of Titan's dune sand.Comment: Published online on Nature Geoscience on 13 April 201
Increased insolation threshold for runaway greenhouse processes on Earth like planets
Because the solar luminosity increases over geological timescales, Earth
climate is expected to warm, increasing water evaporation which, in turn,
enhances the atmospheric greenhouse effect. Above a certain critical
insolation, this destabilizing greenhouse feedback can "runaway" until all the
oceans are evaporated. Through increases in stratospheric humidity, warming may
also cause oceans to escape to space before the runaway greenhouse occurs. The
critical insolation thresholds for these processes, however, remain uncertain
because they have so far been evaluated with unidimensional models that cannot
account for the dynamical and cloud feedback effects that are key stabilizing
features of Earth's climate. Here we use a 3D global climate model to show that
the threshold for the runaway greenhouse is about 375 W/m, significantly
higher than previously thought. Our model is specifically developed to quantify
the climate response of Earth-like planets to increased insolation in hot and
extremely moist atmospheres. In contrast with previous studies, we find that
clouds have a destabilizing feedback on the long term warming. However,
subsident, unsaturated regions created by the Hadley circulation have a
stabilizing effect that is strong enough to defer the runaway greenhouse limit
to higher insolation than inferred from 1D models. Furthermore, because of
wavelength-dependent radiative effects, the stratosphere remains cold and dry
enough to hamper atmospheric water escape, even at large fluxes. This has
strong implications for Venus early water history and extends the size of the
habitable zone around other stars.Comment: Published in Nature. Online publication date: December 12, 2013.
Accepted version before journal editing and with Supplementary Informatio
Distinct roles of Hoxa2 and Krox20 in the development of rhythmic neural networks controlling inspiratory depth, respiratory frequency, and jaw opening
<p>Abstract</p> <p>Background</p> <p>Little is known about the involvement of molecular determinants of segmental patterning of rhombomeres (r) in the development of rhythmic neural networks in the mouse hindbrain. Here, we compare the phenotypes of mice carrying targeted inactivations of <it>Hoxa2</it>, the only <it>Hox </it>gene expressed up to r2, and of <it>Krox20</it>, expressed in r3 and r5. We investigated the impact of such mutations on the neural circuits controlling jaw opening and breathing in newborn mice, compatible with Hoxa2-dependent trigeminal defects and direct regulation of <it>Hoxa2 </it>by Krox20 in r3.</p> <p>Results</p> <p>We found that <it>Hoxa2 </it>mutants displayed an impaired oro-buccal reflex, similarly to <it>Krox20 </it>mutants. In contrast, while <it>Krox20 </it>is required for the development of the rhythm-promoting parafacial respiratory group (pFRG) modulating respiratory frequency,<it> Hoxa2 </it>inactivation did not affect neonatal breathing frequency. Instead, we found that <it>Hoxa2</it><sup>-/- </sup>but not <it>Krox20</it><sup>-/- </sup>mutation leads to the elimination of a transient control of the inspiratory amplitude normally occurring during the first hours following birth. Tracing of r2-specific progenies of <it>Hoxa2 </it>expressing cells indicated that the control of inspiratory activity resides in rostral pontine areas and required an intact r2-derived territory.</p> <p>Conclusion</p> <p>Thus, inspiratory shaping and respiratory frequency are under the control of distinct <it>Hox</it>-dependent segmental cues in the mammalian brain. Moreover, these data point to the importance of rhombomere-specific genetic control in the development of modular neural networks in the mammalian hindbrain.</p
Ibuprofen-loaded calcium phosphate granules : combination of innovative characterization methods to relate mechanical strength to drug location
This paper studies the impact of the location of a drug substance on the physicochemical and mechanical properties of two types of calcium phosphate granules loaded with seven different contents of ibuprofen, ranging from 1.75% to 46%. These implantable agglomerates were produced by either low or high shear granulation. Unloaded Mi-Pro pellets presented higher sphericity and mechanical properties, but were slightly less porous than Kenwood granules (57.7% vs 61.2%). Nevertheless, the whole expected quantity of ibuprofen could be integrated into both types of granules. A combination of surface analysis, using near-infrared (NIR) spectroscopy coupling chemical imaging, and pellet porosity, by mercury intrusion measurements, allowed ibuprofen to be located. It was shown that, from 0% to 22% drug content, ibuprofen deposited simultaneously on the granule surface, as evidenced by the increase in surface NIR signal, and inside the pores, as highlighted by the decrease in pore volume. From 22%, porosity was almost filled, and additional drug substance coated the granule surfaces, leading to a large increase in the surface NIR signal. This coating was more regular for Mi-Pro pellets owing to their higher sphericity and greater surface deposition of drug substance. Unit crush tests using a microindenter revealed that ibuprofen loading enhanced the mechanical strength of granules, especially above 22% drug content, which was favorable to further application of the granules as a bone defect filler
Order parameter configurations in the Lifshitz-type incommensurate ferroelectric thin films
The Dzialoshinskii model of periodic and helicoidal structures has been
analyzed without neglecting of the amplitude function oscillations. The
amplitude function oscillations are shown to be important for understanding of
the nature of the phase function. Analytic consideration is carried out in the
limit of small anisotropy (neglecting the cosine term in the Hamiltonian).
Surprisingly, the phase jumps survive even in the limit of the vanishing
anisotropy
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