科西嘉大学

Research on mega sport events and tourism demand has largely overlooked domestic tourism and relied on aggregated data that mask individual behavioural adjustments. Using Paris 2024 as a case study, we propose a methodology to estimate the direct impact of mega sport events on domestic tourism at the individual level. A retrospective paired-sample survey is used to construct a two-period panel dataset (2023–2024). Individuals are classified as positively affected, negatively affected, or unaffected using self-reported motivations validated by counterfactual behaviour absent the event to mitigate ex-post rationalisation bias. Tourism demand remains unchanged based on the full sample due to offsetting behavioural responses: travel versus stay-at-home attraction among positively affected, and substitution versus crowding-out among negatively affected. However, focusing on actual travellers, affected individuals exhibit a larger increase in overnight stays than unaffected residents, without increasing visit frequency. Micro-level approaches are critical to capture how mega events reshape tourism demand.

Various studies, including morpho-taxonomic identifications, have indicated that commercial spirulina cultures (Limnospira spp.) can be contaminated by other cyanobacteria without establishing a connection with the potential presence of cyanotoxins. The taxonomy and nomenclature of cyanobacteria has changed significantly since the usage of phylogenetic methods and reclassification could lead to confusion in the designation of taxa previously identified as toxin producers. It therefore appears necessary to characterize the cyanosphere of commercial spirulina cultures in the light of these recent developments. In a collection of six spirulina cultivars used in commercial biomass production, we detected a recurrent dominant cyanobacterial contaminant using 16S rRNA gene amplicon sequencing. Further, Next-Generation Sequencing as well as genetic and morphological characterization pointed towards the genus Sodalinema. A comprehensive analysis of five Sodalinema available genomes as well as our novel metagenome-assembled genome did not reveal any genes involved in the synthesis of cyanotoxins, which suggested that this contaminant is harmless. Still, to avoid valuable biomass related financial loss, we took advantage of spirulina capacity to utilize various forms of nitrogen to set up a procedure to control the proliferation of Sodalinema sp. Finally, a glimpse into heterotrophic contamination of those cultivars indicated that the bacterial composition is very diverse but still several phyla appeared to be very common in open-pond cultivation of spirulina in the Mediterranean region.

Following the determination of the chemical compositions of leaf, stem bark and root essential oils from Isolona dewevrei (Annonaceae), those of the flowers and fruits are investigated for the first time. Analyses by combination of GC(RI), GC-MS and 13C-NMR techniques led to the identification of fifty-three constituents (97.6-99.4%) and seventy-three compounds (97.7-99.0%) in the flower and fruit oils, respectively. The flower oil is rich in oxygenated sesquiterpenes and monoterpene hydrocarbons (49.8-73.1% and 4.6-32.2%, respectively), with caryophyllene oxide (37.0-52.1%), limonene (10.8-13.2%), p-cymene (9.6-11.1%), terpinen-4-ol (4.1-8.5%), humulene oxide II (5.1-5.7%) and alismol (3.1-6.1%) as main constituents. Monoterpene hydrocarbons (30.6-62.8%), sesquiterpene hydrocarbons (16.1-32.3%) and oxygenated sesquiterpenes (11.5-30.8%) are prevalent in the fruit oil, which is dominated by (E)-beta-ocimene (13.5-28.3%), (Z)-beta-ocimene (5.7-14.9%), sabinene (5.4-12.6%) and germacrene D (2.4-12.5%). Some identified compounds such as (10 beta H)-1 beta,8 beta-oxido-cadina-4-ene, (5 alpha H,10 beta Me)-6,12-oxido-elema-1,3,6,11(12)-tetraene, germacrene D-8-one, (7 alpha H)-germacrene D-8 alpha-ol, cadina-1(10),4-dien-8 beta-ol and (1 beta H,5 beta H)-6,12-oxido-guaia-6,10(14),11(12)-trien-4 alpha-ol, could serve as chemotaxonomic markers of this species.

This paper introduces differential-geometric methods to study n-dimensional locally conformally flat spaces as submanifolds in pin+2. We derive explicit formulas relating intrinsic and ambient differentialgeometric objects, including curvature tensors, the codifferential, and Laplacian operators. We apply this approach to Friedmann-Lema & icirc;tre-Robertson-Walker (FLRW) spaces using newfound embedding formulas, obtaining new and simplified expressions for the photon propagator in four dimensions.

We introduce the multivariate Log S-fBM model (mLog S-fBM), extending the univariate framework proposed by Wu et al. to the multidimensional setting. We define the multidimensional Stationary fractional Brownian motion (mS-fBM), characterized by marginals following S-fBM dynamics and a specific cross-covariance structure. It is parametrized by a correlation scale T, marginal-specific intermittency parameters and Hurst exponents, as well as their multidimensional counterparts: the co-intermittency matrix and the co-Hurst matrix. The mLog S-fBM is constructed by modeling volatility components as exponentials of the mS-fBM, preserving the dependence structure of the Gaussian core. We demonstrate that the model is well-defined for any co-Hurst matrix with entries in [0, 1/2[, supporting vanishing co-Hurst parameters to bridge rough volatility and multifractal regimes. We generalize the small intermittency approximation technique to the multivariate setting to develop an efficient Generalized Method of Moments calibration procedure, estimating cross-covariance parameters for pairs of marginals. We validate it on synthetic data and apply it to S&P 500 market data, modeling stock return fluctuations. Diagonal estimates of the stock Hurst matrix, corresponding to single-stock log-volatility Hurst exponents, are close to 0, indicating multifractal behavior, while co-Hurst off-diagonal entries are close to the Hurst exponent of the S&P 500 index (H ≈ 0.12), and co-intermittency off-diagonal entries align with univariate intermittency estimates.