Narcissus assoanus Dufour a été observée pour la première fois sur le Puy de Crouel (Puy-de-Dôme). Cette note discute de l’identification, de l’écologie et de la répartition de cette espèce ...d’affinité méditerranéenne. L’origine de cette nouvelle station est discutée brièvement.
Nous inscrivons notre démarche dans le paradigme de l’énaction (Varela et al. 1991) qui postule que toute cognition s’opère par le biais du mouvement dans un contexte d’interactions ...corps-environnement. L’objectif de cet article est de repenser la théorie du signe selon Saussure (1916/1996), présentée comme désincarnée et décontextualisée, à l’aune de ce paradigme récent, à la suite de Bottineau (2012a,b,c,d ; 2017a,b,c). Nous utilisons pour cela la Théorie de la Saillance Submorphologique (Grégoire, 2012a ; 2014 ; 2015; 2017a,b,c,d) qui postule que l’avènement du sens en discours se fonde sur un comportement simplexe (Berthoz 2009) et vicariant (Berthoz 2013) de mise en saillance d’actions bioculturelles. Nous proposerons au préalable une terminologie pour distinguer les actions linguistiques de premier ordre et les unités linguistiques de second ordre, ce qui apparaît fondamental pour tout abord des notions de signe, signifiant et signifié.
We have experimentally investigated the interactions between floating magnetic spheres which are submitted to a vertical magnetic field, ensuring a tunable repulsion, while capillary forces induce ...attraction. We emphasize the complex arrangements of floating bodies. The equilibrium distance between particles exhibits hysteresis when the applied magnetic field is modified. Irreversible processes are evidenced. Symmetry breaking is also found for three identical floating bodies when the strength of the magnetic repulsion is tuned. We propose a Dejarguin-Landau-Verwey-Overbeek (DLVO)-like potential, i.e., an interaction potential with a primary and a secondary minimum, capturing the main physical features of the magnetocapillary interaction, which is relevant for self-assembly.
Abstract We estimate the efficiency of mitigating the lensing B -mode polarization, the so-called delensing, for the LiteBIRD experiment with multiple external data sets of lensing-mass tracers. The ...current best bound on the tensor-to-scalar ratio, r , is limited by lensing rather than Galactic foregrounds. Delensing will be a critical step to improve sensitivity to r as measurements of r become more and more limited by lensing. In this paper, we extend the analysis of the recent LiteBIRD forecast paper to include multiple mass tracers, i.e., the CMB lensing maps from LiteBIRD and CMB-S4-like experiment, cosmic infrared background, and galaxy number density from Euclid - and LSST-like survey. We find that multi-tracer delensing will further improve the constraint on r by about 20%. In LiteBIRD , the residual Galactic foregrounds also significantly contribute to uncertainties of the B -modes, and delensing becomes more important if the residual foregrounds are further reduced by an improved component separation method.
Abstract We study the possibility of using the LiteBIRD satellite B -mode survey to constrain models of inflation producing specific features in CMB angular power spectra. We explore a particular ...model example, i.e. spectator axion-SU(2) gauge field inflation. This model can source parity-violating gravitational waves from the amplification of gauge field fluctuations driven by a pseudoscalar “axionlike” field, rolling for a few e-folds during inflation. The sourced gravitational waves can exceed the vacuum contribution at reionization bump scales by about an order of magnitude and can be comparable to the vacuum contribution at recombination bump scales. We argue that a satellite mission with full sky coverage and access to the reionization bump scales is necessary to understand the origin of the primordial gravitational wave signal and distinguish among two production mechanisms: quantum vacuum fluctuations of spacetime and matter sources during inflation. We present the expected constraints on model parameters from LiteBIRD satellite simulations, which complement and expand previous studies in the literature. We find that LiteBIRD will be able to exclude with high significance standard single-field slow-roll models, such as the Starobinsky model, if the true model is the axion-SU(2) model with a feature at CMB scales. We further investigate the possibility of using the parity-violating signature of the model, such as the TB and EB angular power spectra, to disentangle it from the standard single-field slow-roll scenario. We find that most of the discriminating power of LiteBIRD will reside in BB angular power spectra rather than in TB and EB correlations.
Abstract We explore the capability of measuring lensing signals in LiteBIRD full-sky polarization maps. With a 30 arcmin beam width and an impressively low polarization noise of 2.16 μ K-arcmin, ...LiteBIRD will be able to measure the full-sky polarization of the cosmic microwave background (CMB) very precisely. This unique sensitivity also enables the reconstruction of a nearly full-sky lensing map using only polarization data, even considering its limited capability to capture small-scale CMB anisotropies. In this paper, we investigate the ability to construct a full-sky lensing measurement in the presence of Galactic foregrounds, finding that several possible biases from Galactic foregrounds should be negligible after component separation by harmonic-space internal linear combination. We find that the signal-to-noise ratio of the lensing is approximately 40 using only polarization data measured over 80% of the sky. This achievement is comparable to Planck 's recent lensing measurement with both temperature and polarization and represents a four-fold improvement over Planck 's polarization-only lensing measurement. The LiteBIRD lensing map will complement the Planck lensing map and provide several opportunities for cross-correlation science, especially in the northern hemisphere.
Abstract We present a study of the impact of a beam far side-lobe lack of knowledge on the measurement of the Cosmic Microwave Background B -mode signal at large scale. Beam far side-lobes induce a ...mismatch in the transfer function of Galactic foregrounds between the dipole and higher multipoles which degrads the performances of component separation methods. This leads to foreground residuals in the CMB map. It is expected to be one of the main source of systematic effects in future CMB polarization observations. Thus, it becomes crucial for all-sky survey missions to take into account the interplays between beam systematic effects and all the data analysis steps. LiteBIRD is the ISAS/JAXA second strategic large-class satellite mission and is dedicated to target the measurement of CMB primordial B modes by reaching a sensitivity on the tensor-to-scalar ratio r of σ ( r ) ≤ 10 -3 assuming r = 0. The primary goal of this paper is to provide the methodology and develop the framework to carry out the end-to-end study of beam far side-lobe effects for a space-borne CMB experiment. We introduce uncertainties in the beam model, and propagate the beam effects through all the steps of the analysis pipeline, most importantly including component separation, up to the cosmological results in the form of a bias δr . As a demonstration of our framework, we derive requirements on the calibration and modeling for the LiteBIRD 's beams under given assumptions on design, simulation, component separation method and allocated error budget. In particular, we assume a parametric method of component separation with no mitigation of the far side-lobes effect at any stage of the analysis pipeline. We show that δr is mostly due to the integrated fractional power difference between the estimated beams and the true beams in the far side-lobes region, with little dependence on the actual shape of the beams, for low enough δr . Under our set of assumptions, in particular considering the specific foreground cleaning method we used, we find that the integrated fractional power in the far side-lobes should be known at the level of ∼ 10 -4 , to achieve the required limit on the bias δr < 1.9 × 10 -5 . The framework and tools developed for this study can be easily adapted to provide requirements under different design, data analysis frameworks and for other future space-borne experiments, such as PICO or CMB-Bharat. We further discuss the limitations of this framework and potential extensions to circumvent them.
La mesure de l’insécurité alimentaire est la préoccupation majeure des pays du Sahel comme le Burkina Faso pour anticiper les crises. Ce travail a pour objectif de déterminer les relations entre les ...variables collectées régulièrement par les systèmes d’information nationaux et les résultats primaires de la sécurité alimentaire que sont la consommation alimentaire des ménages et l’évolution des avoirs relatifs aux moyens d’existence. Cela permet aux analystes de suivre et d’informer rapidement sur l’évolution de la situation alimentaire et de faciliter la prise de décision. Ces informations permettront également d’orienter la réponse en direction des populations les plus affectées. Les résultats des enquêtes de vulnérabilité conduites au Burkina Faso sur plus de 20000 ménages en 2016, 2017 et 2018 et représentatifs au niveau provincial ont servi de base de travail. Des analyses de corrélation et de régression ont été effectuées entre la production céréalière totale, la variation annuelle de la production, les prix des céréales, les dépenses alimentaires des ménages d’une part, et les indices d’évaluation de l’insécurité alimentaire (indice des stratégies d’adaptation basées sur la consommation alimentaire, et stratégies d’adaptation basées sur les moyens de subsistance) d’autre part. Les bonnes productions agricoles céréalières de la province influencent positivement le niveau de consommation alimentaire des ménages et réduisent leur recours à des stratégies extrêmes basées sur les moyens d’existence et sur la consommation alimentaire. Le prix élevé des céréales et sa forte variation impactent négativement les moyens de subsistance et la consommation alimentaire des ménages, tout en accentuant leur recours à des stratégies extrêmes d’adaptation, surtout dans les zones de faible production céréalière. En plus, lorsque les dépenses alimentaires des ménages sont inférieures à 50% des dépenses totales, cela favorise la préservation des moyens de subsistance et améliore leur consommation alimentaire. À l’inverse, lorsque les dépenses sont supérieures à 75%, la vulnérabilité des ménages face à la baisse de la production agricole et à la hausse des prix des céréales est accentuée. Les niveaux de corrélation observés entre les variables étudiées sont dans l'ensemble relativement faibles, mais leur combinaison permet d’améliorer significativement les régressions. Une étude à l’échelle de la région devrait permettre de dégager des relations plus intéressantes. Mots clés : Insécurité alimentaire, Consommation alimentaire, Moyens de subsistance, prix des céréales, production céréalière, Burkina Faso
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