Cloud Atlas: Unraveling the vertical cloud structure with the time-series spectrophotometry of an unusually red brown dwarf

Rotational modulations of emission spectra in brown dwarf and exoplanet atmospheres show that clouds are often distributed non-uniformly in these ultracool atmospheres. The spatial heterogeneity in cloud distribution demonstrates the impact of atmospheric dynamics on cloud formation and evolution. In this study, we update the Hubble Space Telescope (HST) time-series data analysis of the previously reported rotational modulations of WISEP J004701+680352 -- an unusually red late-L brown dwarf with a spectrum similar to that of the directly imaged planet HR8799e. We construct a self-consistent spatially heterogeneous cloud model to explain the Hubble Space Telescope and the Spitzer time-series observations, as well as the time-averaged spectra of WISE0047. In the heterogeneous cloud model, a cloud thickness variation of around one pressure scale height explains the wavelength dependence in the HST near-IR spectral variability. By including disequilibrium CO/$CH_4$ chemistry, our models also reproduce the redder $J-K_{\rm s}$ color of WISE0047 compared to that of field brown dwarfs. We discuss the impact of vertical cloud structure on atmospheric profile and estimate the minimum eddy diffusivity coefficient for other objects with redder colors. Our data analysis and forward modeling results demonstrate that time-series spectrophotometry with a broad wavelength coverage is a powerful tool for constraining heterogeneous atmospheric structure.Comment: accepted for publication in The Astrophysical Journa

Modelling the response surface to predict the hydrodynamic diameters of theranostic magnetic siRNA nanovectors

International audienceShort interfering RNAs (siRNAs) appear to be a promising tool to treat various human diseases, such as cancer via the RNA interference (RNAi) mechanism. Since the systemic administration of siRNAs is limited by their capacity to attain the site of action, novel delivery systems are needed. Previously, we reported the formulation of magnetic siRNA nanovectors (MSN) using electrostatic assembly of the following components: (1) functionalized superparamagnetic iron oxide nanoparticles (SPIONs) able to act as agents for magnetic resonance imaging (MRI) and/or thermal therapy, (2) siRNAs as active molecules and (3) chitosan to protect siRNAs and to enhance their transfection efficacy. In this work, experimental design was used to further improve the formulation protocol and to optimize the component quantities. The aim was to obtain response surface plots that will help to optimize and predict the component quantities of the MSNs regarding their hydrodynamic diameter (DH). The influent parameters of the formulation process were determined using a Plackett-Burman design. The results show that the order of incorporation of the components is the most influent parameter on the DH of MSNs. A Box-Behnken design was used to optimize the component quantities. The model equations provided the parameters to obtain MSNs with DH smaller than 100nm to allow their systemic administration

Use of experimental design methodology for the development of new magnetic siRNA nanovectors (MSN).

International audienceShort interfering RNAs (siRNAs) can downregulate the synthesis of proteins and thus be used to treat certain diseases where the protein synthesis is upregulated, such as cancer. The challenge is to deliver siRNAs in the target cell as they are rapidly degraded by nucleases and have difficulties to cross the cellular membranes. Superparamagnetic iron oxide nanoparticles (SPIONs) are widely studied as platforms for smart biocompatible nanosystems which can be used for magnetic drug targeting and magnetic resonance imaging. The aim of this work was to combine siRNAs, SPIONs, and chitosan, to develop new magnetic siRNA nanovectors suitable for systemic administration. In a first time, the one factor at a time (OFAT) methodology was used to adjust different formulation parameters and to test the feasibility of such a formulation. In a second time, design of experiment (DOE) methodology was used to analyze the influence of these formulation parameters on the physicochemical characteristics hydrodynamic diameter (DH) and ζ-potential. Finally, four MSNs suitable for systemic administration could be identified using the OFAT method. The DOE method showed a significant effect of CR and [NaNO3] on the DH and a significant effect of MR and [siRNA] on the ζ-potential of the nanocarriers

PrPd accumulation in organs of ARQ/ARQ sheep experimentally infected with BSE by peripheral routes

To study the pathogenesis of bovine spongiform encephalopathy infection in small ruminants, two Lacaune sheep with the AA136RR154QQ171 and one with the AA136RR154RR171 genotype for the prion protein, were inoculated with a brain homogenate from a French cattle BSE case by peripheral routes. Sheep with the ARQ/ARQ genotype are considered as susceptible to prion diseases contrary to those with the ARR/ARR genotype. The accumulation of disease-associated prion protein (PrPd) was analysed by biochemical and immunohistochemical methods. No PrPd accumulation was detected in samples from the ARR/ARR sheep 2 years post inoculation. In the two ARQ/ARQ sheep that had scrapie-like clinical symptoms, PrPd was found in the central, sympathetic and enteric nervous systems and in lymphoid organs. Remarkably, PrPd was also detected in some muscle types as well as in all peripheral nerves that had not been reported previously thus revealing a widespread distribution of BSE-associated PrPd in sheep tissues

Neurorehabilitation through Hippotherapy on Neurofunctional Sequels of Stroke: Effect on Patients’ Functional Independence, Sensorimotor/Cognitive Capacities and Quality of Life, and the Quality of Life of Their Caregivers—A Study Protocol

Background: Stroke is a high burden illness and the second leading cause of worldwide disability with generally poor recovery rates. Robust benefits of hippotherapy, a novel neurorehabilitation approach, in functional recovery following various severe neurological disabling conditions has been shown. In the present study, we will analyze the effect of a hippotherapy program on the outcome of post-stroke patients in the first year post-stroke. Method: A randomized controlled clinical trial on the effectiveness of hippotherapy (4 weeks/18 weeks hippotherapy/conventional neurorehabilitation) versus conventional neurorehabilitation alone (22 weeks) will be conducted over 48 weeks. In the treated group, one-hour daily hippotherapy sessions will be exclusively conducted during the hippotherapy’s cycles, alternated with periods of conventional neurorehabilitation. A test battery will measure both the functional and psychological outcomes. The primary endpoint will be the patient’s functional independence. The secondary endpoints will measure the sensorimotor function, autonomy, and quality of life, as well as the caregivers’ quality of life. Results and conclusion: Individual brain connectome, life history and personality construct influence the brain’s functional connectivity and are central to developing optimal tailored neurorehabilitation strategies. According to our current practice, hippotherapy allows the enhancement of substantial neuroplastic changes in the injured brain with significant neurological recovery. The protocol aims to confirm those issues. Trial registration in ClinicalTrials.gov NCT04759326 accessed on 19 February 2021

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