An Exo-Kuiper Belt with an Extended Halo around HD 191089 in Scattered Light

We have obtained Hubble Space Telescope STIS and NICMOS and Gemini/GPI scattered-light images of the HD 191089 debris disk. We identify two spatial components: a ring resembling the Kuiper Belt in radial extent (FWHM ∼ 25 au, centered at ∼46 au) and a halo extending to ∼640 au. We find that the halo is significantly bluer than the ring, consistent with the scenario that the ring serves as the birth ring for the smaller dust in the halo. We measure the scattering phase functions in the 30°-150° scattering-angle range and find that the halo dust is more forward- and backward-scattering than the ring dust. We measure a surface density power-law index of -0.68 ± 0.04 for the halo, which indicates the slowdown of the radial outward motion of the dust. Using radiative transfer modeling, we attempt to simultaneously reproduce the (visible) total and (near-infrared) polarized intensity images of the birth ring. Our modeling leads to mutually inconsistent results, indicating that more complex models, such as the inclusion of more realistic aggregate particles, are needed

Direct Imaging of the HD 35841 Debris Disk: a Polarized Dust Ring from Gemini Planet Imager and an Outer Halo From \u3ci\u3eHST/\u3c/i\u3eSTIS

We present new high resolution imaging of a light-scattering dust ring and halo around the young star HD 35841. Using spectroscopic and polarimetric data from the Gemini Planet Imager in H-band (1.6 μm), we detect the highly inclined (i = 85°) ring of debris down to a projected separation of ∼12 au (∼0.″12) for the first time. Optical imaging from HST/STIS shows a smooth dust halo extending outward from the ring to \u3e140 au (\u3e1.″4). We measure the ring\u27s scattering phase function and polarization fraction over scattering angles of 22°-125°, showing a preference for forward scattering and a polarization fraction that peaks at ∼30% near the ansae. Modeling of the scattered-light disk indicates that the ring spans radii of ∼60-220 au, has a vertical thickness similar to that of other resolved dust rings, and contains grains as small as 1.5 μm in diameter. These models also suggest the grains have a low porosity, are more likely to consist of carbon than astrosilicates, and contain significant water ice. The halo has a surface brightness profile consistent with that expected from grains pushed by radiation pressure from the main ring onto highly eccentric but still bound orbits. We also briefly investigate arrangements of a possible inner disk component implied by our spectral energy distribution models, and speculate about the limitations of Mie theory for doing detailed analyses of debris disk dust populations

Détection de l'hypertension intracrânienne par la mesure échographique du diamètre de l'enveloppe du nerf optique chez l'enfant (étude préalable rétrospective en réanimation pédiatrique sur l'année 2010)

LYON1-BU Santé (693882101) / SudocSudocFranceF

Prévalence et facteurs prédictifs de non protection tétanique

PARIS7-Xavier Bichat (751182101) / SudocSudocFranceF

Is the focus on “ecosystems” a liability in the research on nature’s services?

For the last 20 years, the concept of ecosystem has constituted one of the key pillars on which the study of “ecosystem services”, i.e., the benefits that human populations derive from nature, has been based. Yet, at this stage, one could argue that, in general and especially in fields related to agriculture, the ecosystem framework tends to limit unnecessarily the range of benefits to humans that are considered in practice, to hinder the necessary measurement of services, and to make it challenging to convince individuals to take nature’s services into account in their decision making. In the present Perspective piece, we analyze these 3 arguments in detail, conclude that the current focus on ecosystems is more a liability than an asset in the field, and suggest a return to the less constraining notions of “nature’s functions and services”, without a necessary tie to ecosystems

Effect of spatial scale of soil data on estimates of soil ecosystem services: Case study in 100 km 2 area in France

International audienc

Comparison of empirical and process-based modelling to quantify soil-supported ecosystem services on the Saclay plateau (France)

Following the rapid development of models to assess and map ecosystem services (ES) in the last decades, there is an increasing need for comparative studies testing their efficiency and accuracy against field data. The representation of soils in these models is often oversimplified and remains a major source of uncertainty in ES assessment and mapping. In this context, a first objective of the present article is to develop two approaches of increasing complexity (empirical versus process-based) integrating a realistic representation of soils, to map two provisioning (biomass and water) and two regulating (water quality and global climate) soil-supported ES on the Saclay plateau (France). A second objective is to compare them according to their relative ability to replicate direct measurements (absolute accuracy) in a cultivated soil and to translate gradients in soil properties into differences in levels of the soil-supported ES (relative accuracy). On the basis of currently available models, the soil-supported ES can be assessed only under a homogeneous simplified crop rotation. For the fixed land management used in this research, the soil type significantly influences the levels of the considered services. The process-based modelling is effective only in deep, homogeneous, and cultivated soils. By contrast, the empirical modelling is effective over a larger range of soils, but mostly for provisioning services. The ability to integrate a realistic representation of soils in ES assessment and mapping with common tools and models is currently limited in terms of land-use, soil diversity, or types of ES. Increasing the accuracy of ES assessment and mapping requires pursuing the effort towards developing and validating models that explicitly take into account soil processes and properties

Targeted Apc;Twist Double-Mutant Mice: A New Model of Spontaneous Osteosarcoma That Mimics the Human Disease123

TWIST and adenomatosis polyposis coli (APC) are critical signaling factors in normal bone development. In previous studies examining a homogeneously treated cohort of pediatric osteosarcoma patients, we reported the frequent and concurrent loss of both TWIST and APC genes. On these bases, we created a related animal model to further explore the oncogenic cooperation between these two genes. We performed intercrosses between twist-null/+ and Apc1638N/+ mice and studied their progeny. The Apc1638N/+;twistnull/+ mice developed bone abnormalities observed by macroscopic skeletal analyses and in vivo imaging. Complementary histologic, cellular, and molecular analyses were used to characterize the identified bone tumors, including cell culture and immunofluorescence of bone differentiation markers. Spontaneous localized malignant bone tumors were frequently identified in Apc1638N/+;twist-null/+ mice by in vivo imaging evaluation and histologic analyses. These tumors possessed several features similar to those observed in human localized osteosarcomas. In particular, the murine tumors presented with fibroblastic, chondroblastic, and osteoblastic osteosarcoma histologies, as well as mixtures of these subtypes. In addition, cellular analyses and bone differentiation markers detected by immunofluorescence on tumor sections reproduced most murine and human osteosarcoma characteristics. For example, the early bone differentiation marker Runx2, interacting physically with hypophosphorylated pRb, was undetectable in these murine osteosarcomas, whereas phosphorylated retinoblastoma was abundant in the osteoblastic and chondroblastic tumor subtypes. These characteristics, similar to those observed in human osteosarcomas, indicated that our animal model may be a powerful tool to further understand the development of localized osteosarcoma

Cold Debris Disks as Strategic Targets for the 2020s

Cold debris disks (T<200 K) are analogues to the dust in the Solar System's Kuiper belt--dust generated from the evaporation and collision of minor bodies perturbed by planets, our Sun, and the local interstellar medium. Scattered light from debris disks acts as both a signpost for unseen planets as well as a source of contamination for directly imaging terrestrial planets, but many details of these disks are poorly understood. We lay out a critical observational path for the study of nearby debris disks that focuses on defining an empirical relationship between scattered light and thermal emission from a disk, probing the dynamics and properties of debris disks, and directly determining the influence of planets on disks. We endorse the findings and recommendations published in the National Academy reports on Exoplanet Science Strategy and Astrobiology Strategy for the Search for Life in the Universe. This white paper extends and complements the material presented therein with a focus on debris disks around nearby stars. Separate complementary papers are being submitted regarding the inner warm regions of debris disks (Mennesson et al.), the modeling of debris disk evolution (Gaspar et al.), studies of dust properties (Chen et al.), and thermal emission from disks (Su et al.)