42 research outputs found

    Exploring the Bimodal Solar System via Sample Return from the Main Asteroid Belt: The Case for Revisiting Ceres

    Get PDF
    Abstract: Sample return from a main-belt asteroid has not yet been attempted, but appears technologically feasible. While the cost implications are significant, the scientific case for such a mission appears overwhelming. As suggested by the “Grand Tack” model, the structure of the main belt was likely forged during the earliest stages of Solar System evolution in response to migration of the giant planets. Returning samples from the main belt has the potential to test such planet migration models and the related geochemical and isotopic concept of a bimodal Solar System. Isotopic studies demonstrate distinct compositional differences between samples believed to be derived from the outer Solar System (CC or carbonaceous chondrite group) and those that are thought to be derived from the inner Solar System (NC or non-carbonaceous group). These two groups are separated on relevant isotopic variation diagrams by a clear compositional gap. The interface between these two regions appears to be broadly coincident with the present location of the asteroid belt, which contains material derived from both groups. The Hayabusa mission to near-Earth asteroid (NEA) (25143) Itokawa has shown what can be learned from a sample-return mission to an asteroid, even with a very small amount of sample. One scenario for main-belt sample return involves a spacecraft launching a projectile that strikes an object and flying through the debris cloud, which would potentially allow multiple bodies to be sampled if a number of projectiles are used on different asteroids. Another scenario is the more traditional method of landing on an asteroid to obtain the sample. A significant range of main-belt asteroids are available as targets for a sample-return mission and such a mission would represent a first step in mineralogically and isotopically mapping the asteroid belt. We argue that a sample-return mission to the asteroid belt does not necessarily have to return material from both the NC and CC groups to viably test the bimodal Solar System paradigm, as material from the NC group is already abundantly available for study. Instead, there is overwhelming evidence that we have a very incomplete suite of CC-related samples. Based on our analysis, we advocate a dedicated sample-return mission to the dwarf planet (1) Ceres as the best means of further exploring inherent Solar System variation. Ceres is an ice-rich world that may be a displaced trans-Neptunian object. We almost certainly do not have any meteorites that closely resemble material that would be brought back from Ceres. The rich heritage of data acquired by the Dawn mission makes a sample-return mission from Ceres logistically feasible at a realistic cost. No other potential main-belt target is capable of providing as much insight into the early Solar System as Ceres. Such a mission should be given the highest priority by the international scientific community

    TRY plant trait database – enhanced coverage and open access

    Get PDF
    Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    ARIES-I SiC Composite Low Activation Blanket Design

    No full text

    Micafungin susceptibility of the most common<em> Candida</em> species in 16 French university hospitals : comparison between the EtestÂź and the EUCAST methods (MICACAND study)

    Get PDF
    International audienceObjectives : Micafungin is currently used in France. The aim of this study is to determine its activity against a recent (2014) French collection of Candida isolates. Although EUCAST is the reference method for in vitro antifungal susceptibility testing, it is not commonly used in routine clinical microbiology laboratories. Thus, it is important to evaluate alternative methods. We compared EUCAST and Etest for micafungin susceptibility testing of Candida spp. and we monitored the emergence of resistance. Methods: Sixteen centers (6 in Paris area and 10 across France) participated in a two-months prospective study. Clinical isolates of various Candida species (mainly C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. kefyr and C. krusei, about 10 isolates of each species per center) were tested by Etest, according to manufacturer’s instructions. All isolates were subsequently centralized in one center for MIC determination by EUCAST method. For comparison purposes, Etest MICs were raised to the next higher EUCAST concentration. Resistance was defined based on EUCAST clinical breakpoints or on epidemiological cut-off values when clinical breakpoints were not available. Results : A total number of 933 Candida isolates were tested. The overall agreement (+/- 2 log2 dilutions) between EUCAST and Etest was 97.9%. Species n E-Test EUCAST MIC range MIC range % agreement with Etest % resistance C. albicans 159 ≀ 0.015 - 0.06 ≀ 0.015 - 0.06 100 1.3 C. tropicalis 152 ≀ 0.015 - 0.5 ≀ 0.015 - 1 98.7 0.7 C. parapsilosis 152 ≀ 0.015 - 4 ≀ 0.125 - 4 96.1 1.3 C. glabrata 152 ≀ 0.015 - 0.125 ≀ 0.015 - 1 98.7 3.9 C. kefyr 136 ≀ 0.015 - 0.25 ≀ 0.015 - 0.125 97.8 ND C. krusei 127 ≀ 0.015 - 1 ≀ 0.015 - 0.25 96.9 0 Other Candida species* 55 ≀ 0.015 - 1 ≀ 0.015 - 1 94.5 ND Total 933 ≀ 0.015 - 4 ≀ 0.015 - 4 97.9 ND *: C. lusitaniae, C. guilliermondii, C. norvegensis, C. inconspicua, C. famata, C. pelliculosa, C. lambica, C. sphaerica, C. ciferii, C. catenulata, C. utilis, C. colliculosa, C. nivariensis Conclusions : This study demonstrated a very good agreement between Etest, performed on a routine basis, and EUCAST for micafungin MIC determination. Micafungin resistance among the main Candida species was uncommon

    Update of survival and cost of metastatic melanoma with new drugs: Estimations from the MelBase cohort

    No full text
    International audiencePurpose Since 2011, significant progress was observed in metastatic melanoma (MM), with the commercialisation of seven immunotherapies or targeted therapies, which showed significant improvement in survival. In France, in 2004, the cost of MM was estimated at €1634 per patient; this cost has not been re-estimated since. This study provided an update on survival and cost in real-life clinical practice. Methods Clinical and economic data (treatments, hospitalisations, radiotherapy sessions, visits, imaging and biological exams) were extracted from the prospective MelBase cohort, collecting individual data in 955 patients in 26 hospitals, from diagnosis of metastatic disease until death. Survival was estimated by the Kaplan-Meier method. Costs were calculated from the health insurance perspective using French tariffs. For live patients, survival and costs were extrapolated using a multistate model, describing the 5-year course of the disease according to patient prognostic factors and number of treatment lines. Results Since the availability of new drugs, the mean survival time of MM patients has increased to 23.6 months (95%confidence interval [CI] :21.2;26.6), with 58% of patients receiving a second line of treatment. Mean management costs increased to €269,682 (95%CI:244,196;304,916) per patient. Drugs accounted for 80% of the total cost. Conclusion This study is the first that evaluated the impact of immunotherapies and targeted therapies both on survival and cost in real-life conditions. Alongside the introduction of breakthrough therapies in the first and subsequent lines, MM has been associated with a significant increase in survival but also in costs, raising the question of financial sustainability
    corecore