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Euclid preparation: TBD. Cosmic Dawn Survey: evolution of the galaxy stellar mass function across 0.2<z<6.5 measured over 10 square degrees
No full textInternational audienceThe Cosmic Dawn Survey Pre-launch (PL) catalogues cover an effective 10.13 deg area with uniform deep Spitzer/IRAC data ( mag, 5), the largest area covered to these depths in the infrared. These data are used to gain new insight into the growth of stellar mass across cosmic history by characterising the evolution of the galaxy stellar mass function (GSMF) through and significantly reduces cosmic variance, yielding strong constraints on the abundance of massive galaxies. Results are generally consistent with the literature but now provide firm estimates of number density where only upper limits were previously available. Contrasting the GSMF with the dark matter halo mass function suggests that massive galaxies ( M) at required integrated star-formation efficiencies of 0.25--0.5, in excess of the commonly-held view of ``universal peak efficiency" from studies on the stellar-to-halo mass relation (SHMR). Such increased efficiencies imply an evolving peak in the SHMR at which can be maintained if feedback mechanisms from active galactic nuclei and stellar processes are ineffective at early times. In addition, a significant fraction of the most massive quiescent galaxies are observed to be in place already by --3. The apparent lack in change of their number density by is consistent with relatively little mass growth from mergers. Utilising the unique volume, evidence for an environmental dependence of the galaxy stellar mass function is found all the way through for the first time, though a more careful characterisation of the density field is ultimately required for confirmation
Partitioning Vertices and Edges of Graphs into Connected Subgraphs
No full textInternational audienceArbitrarily partitionable (AP) graphs are graphs that can have their vertices partitioned into arbitrarily many parts inducing connected graphs of arbitrary orders. Since their introduction, several aspects of AP graphs have been investigated in literature, including structural and algorithmic aspects, their connections with other fundamental notions of graph theory, and variants of the original notion. Quite recently, an edge version of AP graphs, called arbitrarily edge-partitionable (AEP) graphs have been introduced and studied, with a special focus on their similarities and discrepancies with AP graphs.In this work, we introduce and study a total variant of AP graphs, called arbitrarily total-partitionable (ATP) graphs, which essentially stand as a combination of AP and AEP graphs, for some particular notion of connectivity for sets of vertices and edges. We establish results of several natures, which we compare to known, similar results for AP and AEP graphs. In particular, we prove that, although the involved definitions are rather close, being AP, AEP, and/or ATP for a graph does not guarantee it also has the other properties. We also establish that deciding whether a tree can be partitioned in this total way is NP-complete in general, and provide sufficient conditions for ATPness in terms of longest paths. We finally raise directions for further work on the topic
Secondary progression activity monitoring in MS despite an early highly active treatment the SPAM study
No full textInternational audienceBackground: Real-world data suggest that the early use of highly active therapies (HAT) may reduce the risk of transition to secondary progressive MS (SPMS). However, current knowledge about predictive factors of outcomes needs to be improved. The primary objective of this study was to determine factors associated with the occurrence of SPMS in patients treated early after MS onset with an HAT.Methods: Retrospective, multicentric study based on the French MS database. Patients who initiated a HAT within 5 years after MS onset, EDSS ⩽4, and had a follow-up >5 years were included. The association of each covariate at baseline with time to the occurrence of SPMS was quantified by hazard ratios (HRs) in unadjusted and adjusted Cox proportional hazards models.Results: Two thousand two hundred and thirty-seven patients were included in the analysis: mean age 31.6 years, female/male sex ratio 2.3, and median EDSS 2.0. The estimated probability of reaching SPMS, progression independent of relapse activity (PIRA) and progression independent of activity (PIA) at 10 years was 8%, 22%, and 11%, respectively. After adjustment, we found that female patients (HR 0.64, p = 0.036) had a lower risk of developing SPMS. Older age, EDSS >0 (HR 7.44, p < 0.001), and oral versus intravenous HAT (HR 1.97, p = 0.003) were significantly associated with an increased SPMS risk. Early PIRA and PIA predicted conversion to SPMS.Conclusions: Early HAT use resulted in a low risk of developing SPMS over 10 years. Introducing the HAT before any residual disability was associated with a lower risk of progression
Correlation between serum and saliva sex hormones in young female athletes
No full textInternational audienceBACKGROUND: Saliva sampling provides a practical noninvasive way for biological monitoring of steroid hormones but few studies have focused on saliva sex hormones in female athletes, and it is still unknown whether salivary concentrations are an accurate reflection of blood concentrations in this population. The aim of this study was therefore to evaluate the correlation between serum and saliva estradiol (E2) and progesterone (PG) in 10 young female athletes with normal menstrual cycle.METHODS: Thirty blood and saliva samples were taken at rest in a fasting state in order to analyze E2 and PG concentrations, during 3 different hormonal periods: Status 1: low E2 and low PG (end luteal/early follicular); Status 2: high E2 and low PG (end follicular/peri-ovulatory); Status 3: high PG (mid-luteal).RESULTS: A strong correlation was found between serum and saliva PG (r=0.914, P<0.01), whereas a weaker but still significant relationship was observed between serum and saliva E2 (r=0.755, P<0.01). The most significant correlations obtained for E2 were during Status 2 (r=0.941, P<0.01) and during Status 3 for PG (r=0.817, P<0.01).CONCLUSIONS: Although it remains challenging to produce precise identification with only saliva samples for each menstrual cycle phase, results seem to show that saliva can provide a convenient substitute to serum for sex hormones in female athletes during longitudinal monitoring. This is of particular interest in this population, with the number of female athletes suffering from an altered menstrual cycle, sometimes even during regular menstruation
Analysis of Hopf bifurcation and time-delayed control inmulti-scroll chaotic attractors produced by parallel transformation
No full textInternational audienceThis paper announces Hopf bifurcation and the application of a straightforward time-delayed feedback control (TDFC) method to multi-scroll chaotic Chua attractors, generated through parallel transformation. The paper provides the necessary and sufficient conditions for the existence of these attractors and establishes the critical Hopf bifurcation value at specific two-parameter control values (k). Additionally, the study explores the effectiveness of the TDFC method in transitioning an initially unstable equilibrium point to a stable one. The application of TDFC demonstrates its ability to manage chaotic behaviors by stabilizing unstable equilibrium points, all while preserving the core structure of the system
A semi-parametric distribution stitch based on the Berk-Jones test for French daily precipitation bias correction
No full textModelling daily precipitation data in a large territory is a complex issue due to its asymmetric distribution with few and spatially sparse extremes. Most parametric distributions fail to model rainfall correctly over a large area, and many impact studies use the non-parametric empirical distribution instead of parametric ones, preferring the robustness of the model on the observed data to the extrapolation to unobserved extremes. In the present paper, we built a distributional semi-parametric model for the bias correction of the ERA5-Land reanalysis using the CERRA-Land reanalysis. The proposed inference procedure is constructed as follows.Firstly, we fit an Extended Generalized Pareto (EGP) distribution to the data. These EGP models give a Generalized Pareto distribution in the upper tail while allowing greater flexibility in the lower one. Secondly, for each location, using an adapted version of the Berk-Jones (BJ) statistical test, we propose to replace a portion of the EGP distribution with either the empirical distribution or an eventually lighter-tail parametric distribution such as the Exponentiated Weibull (ExpW) distribution. The final obtained model is a stitch between the EGP, ExpW and the empirical distributions. The proposed semi-parametric stitch model has been evaluated in a bias correction context against classical pure parametric quantile mapping based on Gamma, ExpWand EGP distributions. Comparisons to other classical models show a reduction of the mean absolute and extreme error metrics, especially by removing outliers
Orbit separation and stratification by isotropy classes of piezoelectricity tensors
No full textInternational audienceWe explore an innovative method to compute separating invariants in a real G-variety V. A refinement of Seshadri slice Lemma enables us to decompose V into a union of stable subsets GZ1 ... GZr. It then reduces the problem to separating the orbits in the slices Zi for their normalizers Ni < G. This sequencing allows also to identify efficiently the isotropy class of any point. After the presentation of three types of Seshadri slices for representations of SO3(R), we apply the method to the space of piezoelectricity tensors Piez. It provides a separating set of low cardinality and a complete stratification of Piez by isotropy classes
Intermittency in fluid and MHD turbulence analyzed through the prism of moment scaling predictions of multifractal models
No full textInternational audienceIn the presence of waves due e.g. to gravity, rotation or a quasi-uniform magnetic field, energy transfer time-scales, spectra and physical structures within turbulent flows differ from the fully developed fluid case, but some features remain such as intermittency or quasi-parabolic behaviors of normalized moments of relevant fields. After reviewing some of the roles intermittency can play in various geophysical flows, we present results of direct numerical simulations at moderate resolution and run for long times. We show that the power-law scaling relations between kurtosis K and skewness S found in multiple and diverse environments can be recovered using existing multifractal intermittency frameworks. In the specific context of the She-Lévêque model (1994) generalized to MHD and developed as a two-parameter system in Politano and Pouquet (1995), we find that a parabolic K (S) law can be recovered for maximal intermittency involving the most extreme dissipative structures
