Centre d’études et de Recherches sur l’espace Germanophone

International audience

International audience

We report closed-form formula for calculating the Chi square and higher-order Chi distances between statistical distributions belonging to the same exponential family with affine natural space, and instantiate those formula for the Poisson and isotropic Gaussian families. We then describe an analytic formula for the f-divergences based on Taylor expansions and relying on an extended class of Chi-type distances.

To date, the successful low-temperature synthesis of the aluminosilicate imogolite nanotubes always involved initial concentrations of the reagents in the millimolar range, higher concentrations being reported to lead to the formation of the less well characterized allophane phase. The present work shows that reaction kinetics and not initial concentration control the formation of the nanotubes: substantial amounts of well formed imogolite were obtained from a decimolar initial concentration, i.e. 100 times higher than the "standard" protocol. The allophane-like spheroids expected from the high reagent concentration were not observed in this work, and proto-imogolite was obtained instead.

Despite sanctions being one of the most common and far-reaching forms of economic statecraft, there is a notable absence of research on the gendered effects of economic sanctions on women’s empowerment in general, and more particularly in relation to tourism. This is surprising given that the burden of economic sanctions is overwhelmingly felt by women due to their vulnerable socio-economic and political status in targeted countries. Drawing upon a disciplinary base in international relations and political science and using a gendered lens via a series of interviews, this study sought to explore the gendered effects of economic sanctions on Iranian women’s empowerment in the country’s tourism and hospitality industry. The study’s findings indicate that sanctions have negatively affected and deteriorated economic, psychological, social and political aspects of women empowerment. The results highlight the vulnerability of empowerment within the religio-patriarchal society of Iran. As such economic empowerment is recognized as a major contributor to the overall empowerment of women in Iran which is therefore severely affected by sanctions. Overall, this study fills a significant gap in tourism research by highlighting the gendered implications of a ubiquitous state tool of coercive diplomacy and foreign policy and its effects on women’s empowerment.

Despite its importance to economic growth, the investment behavior of firms remains poorly understood. Existing models ignore irreversibility and the opportunity to wait for new information. Even if some recent literature accounts for these two characteristics, these models ignore information costs. This paper presents a framework for the valuation of investment opportunities accounting for information costs regarding the project cash‐flows. We develop some basic models of irreversible investment to illustrate the option‐like characteristics of investment opportunities under incomplete information. We show how optimal investment rules can be obtained using option pricing theory under incomplete information. It is possible to value real options and investment decisions using our approach in a context of incomplete information. Simulations are provided to illustrate our main results.

Size has become a significant factor in explaining returns. According to the size effect, smaller capitalization stocks on average outperform larger capitalization stocks over long periods of time. This paper first documents the traditional size effect on the French market for the 1986–1998 period. It introduces a new proxy for size, free float, which is argued to be the appropriate measure of size and liquidity for most non‐US markets. Evidence is presented of a negative link between historical returns and free float. The link is significant even outside of the month of January, a notable divergence from results obtained on the NYSE. The rest of the paper is an attempt to take advantage of this ‘ex‐post’ phenomenon on an ‘ex‐ante’ basis, with an empirical study of the link between expected return, risk, and liquidity in a sample consisting of the main 150 stocks quoted on the Paris Bourse between January 1986 and January 1998. Liquidity premiums are estimated for portfolios from both a univariate and a multivariate perspective. The paper shows how risk and liquidity premiums can be used separately or in tandem for market timing and asset allocation. In all cases, the use of both premiums together leads to superior performance. Results confirm our measurements of liquidity and liquidity premiums and supply evidence that liquidity premiums together with risk premiums are useful in active asset management.

The hospitality industry is facing tough competition due to new actors (i.e. online travel agencies, comparison websites, etc.). Furthermore, Covid-19 has made it worse with travel restrictions and health measures. This study aims to identify the needs and expectations of hotel guests in a post-pandemic context, and how hotels can acquire and manage resources in a strategic way. Analytic Hierarchy Process (AHP) was employed to assess the importance of 9 hotel attributes via pairwise comparison. The data were collected from 537 guests who stayed in 3- and 4-star hotels in Paris from April to June 2021. In addition, in-depth interviews of 19 hotel managers were conducted to gain insights into how they are acquiring and managing their resources. Theoretical and practical implications, and future research directions are presented.

Voronoi diagrams are fundamental geometric structures that partition the space into elementary regions of influence defining discrete proximity graphs and dually well-shaped Delaunay triangulations [Aurenhammer & Klein, 2000]. In this video, we explain and illustrate a recent generalization of Voronoi diagrams [Nielsen et al., 2007] to a wide class of distortion measures called Bregman divergences [Banerjee et al., 2005].

Abstract Although hydraulic infrastructure such as levees remain important for flood risk management in the USA, France, and Quebec (Canada), there is increasing emphasis on nonstructural measures, such as regulatory flood maps, to reduce exposure and vulnerability, for example, preventing people from building in high hazard areas. One key concept related to areas protected by levees is that of “residual risk”, that is, the risk from floods greater than the design standard of the levees (levee overtopping) and from levee breach. In this article, we review the legislative framework for regulatory flood maps in the USA, France, and Quebec (Canada) and compare how residual risk behind protective structures is taken into account (or not) in regulatory flood maps. We find big differences in how the USA, France and Canada manage residual risk behind the levees. While in France the area behind levees is part of the regulatory flood prone area, and land use restrictions, building codes, emergency measures and risk communication are mandatory, in the USA the area behind levees is only shown as part of the regulatory flood prone area if the levee is not accredited. In Quebec, regulatory flood maps in general follow the French approach with a few exceptions.

Abstract Consumers' trust in eco‐labels is declining due to the growing number of different kinds of eco‐labels that can be uncertified and related to greenwashing. This paper argues that providing more transparency regarding green supply chains (GSCs) through eco‐labels (such as Cradle to Cradle Certified®) is critical for creating trust and convincing consumers to buy eco‐products over conventional ones. Building on previous literature related to sustainable consumption behavior, green purchasing behavior, Cradle to Cradle certification and GSC management, we develop and test a conceptual model to empirically investigate the links between consumers' trust in eco‐product labels and GSC perceptions in influencing green purchase behavior (GPB) in the case of eco‐friendly fast‐moving consumer goods (FMCGs). By studying a sample of 276 German consumers and applying structural equation modeling, we find that the trust in eco‐product labels and positive perceptions of GSCs are important drivers of GPB. Our research contributes by expanding the knowledge on the factors influencing the acceptance of eco‐products, highlighting the importance of supply chain transparency and trust in GSCs among consumers. We discuss theoretical implications for green product innovation and marketing including eco‐product labeling based on transparent GSCs.

Supply chains’ broad operational capacity and their integrative potential are too relevant to be ignored. However, they are sometimes pursued with limited care for global sustainability concerns. This research paper argues how comprehensive the incorporation of sustainability in supply chain management is, discussing the importance of promoting supply chains rooted in a sustainability mindset, which employs a systems perspective to contribute to the Sustainable Development Goals. Using four cases from the electronics sector, the study proposes a framework that could be used to assess the sustainability within supply chain management as an alternative for the traditional TBL perspective, analyzing the sustainability mindset dimensions: “Knowing” and “Doing”. Also, the paper emphasizes the gap between what companies’ supply chains declare and what they actually would do towards sustainability, proposing that the “Being” dimension of the sustainability mindset is still missing.

We present visible, near IR, and mm-wave observations of RCW 108, a molecular cloud complex in the AraOB1 association that is being eroded by the energetic radiation of two O-type stars in the nearby cluster NGC 6193. The western part of the RCW108 cloud contains an embedded compact HII region, IRAS 16362-4845, ionized by an aggregate of early-type stars. We notice a lack of stars later than A0 in the aggregate and speculate that this might be a consequence of its extreme youth. We examine the distribution of stars displaying IR excesses projected across the molecular cloud. While many of them are located in the densest area of the molecular cloud near IRAS16362-4845, we also find a group concentrating towards the edge of the cloud that faces NGC 6193, as well as some other stars beyond the edge of the molecular cloud. The intense ionizing radiation field by the O stars in NGC6193 is a clear candidate trigger of star formation in the molecular cloud, and we suggest that the existence and arrangement of stars in this region of the cloud supports a scenario in which their formation may be a consequence of this. However, IR excess stars are also present in some areas of the opposite side of the cloud, where no obvious candidate external trigger is identified. The existence of such tracers of recent star formation scattered across the more massive molecular cloud associated with IRAS 16362-4845, and the low star formation efficiency that we derive, indicate that it is in a state to still form stars. This is in contrast to the less massive cloud close to NGC 6193, which seems to be more evolved and mostly already recycled into stars, and whose internal kinematics show hints of having been perturbed by the presence of the massive stars formed out of it.

International audience

The SERENADE project aims to develop and apply the “safer by design” process to create safer nanoproducts.

En domaine littoral, dans un contexte de stabilisation plurimillénaire de la montée du niveau de la mer, une question qui se pose est celle de l’impact des conditions environnementales sur les choix d’implantation des communautés humaines qui s’installent autour des lagunes. L’historiographie a développé des modèles plus ou moins déterministes mais survivent-ils à la confrontation avec les données environnementales récemment acquises? Quels ont été les effets de ces occupations sur l’évolution du littoral et réciproquement, comment les sociétés anciennes ont utilisé, contourné, surmonté ou pas les potentialités et contraintes environnementales spécifiques liées à l’occupation des milieux lagunaires, telles que l’accessibilité, la navigabilité, la vitesse de remblaiement et la hauteur de la colonne d’eau. Nous présentons des données acquises dans le cadre de nombreuses recherches pluridisciplinaires sur différents ports principalement méditerranéens et nous tentons d’estimer le poids des forçages naturels et anthropiques sur la mobilité des rivages à différentes échelles spatiales, ces processus affectant plus ou moins directement l’aménagement et la survie des ports lagunaires. Nous présentons cinq principaux types de contexte portuaire lagunaire différents, qui illustrent l’immense diversité et mobilité de ces milieux, leurs potentialités mais aussi leurs contraintes, la quasi-totalité des trajectoires géomorphologiques des lagunes aboutissant à leur disparition, soit par remblaiement soit par submersion : (1) les bassins lagunaires artificiels, (2) les ports lagunaires remblayés en contexte deltaïque, (3) les ports lagunaires toujours en eau, (4) les ports estuariens et (5) les systèmes de lagune mixte.

This study examines the relationship between green hotel practices and consumer revisit intention, with the mediating mechanisms of brand identification, promotion focus, and green consumption value. A paper-based survey was conducted to collect data from consumers in four-star or above hotels in China. Findings from multivariate data analysis show that green hotel practices positively influence consumer to revisit intention, which is mediated by brand identification and green consumption value. Moreover, consumer promotion focus positively mediates the relationship between green hotel practices and brand identification. The findings validate a unique multi-path mediating model of green hotel practices. They also have important implications for hotel managers interested in developing genuine environmental initiatives to generate positive customer responses.

Research on the impact of open market share repurchases has been hindered by the lack of data available on actual share repurchases in many countries, including the U.S. Using a previously unused database containing detailed information on 36,848 repurchases made by 352 French firms, we show that corporate share repurchases have a significant adverse effect on liquidity as measured by bid-ask spread or depth. Our results also indicate that share repurchases largely reflect contrarian trading rather than managerial timing ability.

The Covid-19 pandemic has profoundly disrupted the worldwide economy, particularly the restaurant sector. To face these challenges, the multi- and omni-channel approaches have been embraced by several firms, especially with the integration of mobile channels and social media. However, no research is conducted to investigate how this integration can be successful in times of crisis, such as pandemic. Therefore, drawing upon the self-determination theory, the present study aims at addressing this research gap by exploring, from both the restaurant owners’ and customers’ perspectives, how an anti-food waste mobile app called Too Good To Go (TGTG) – the largest social case in Europe, is perceived as a strategic distribution channel in the time of pandemic. Based on 18 in-depth interviews with restaurant owners and 22 with customers in Paris, findings highlight the success factors for restaurants to achieve their digital strategies. Theoretical and practical implications, and future research perspectives are presented.

L’analyse multiproxies à haute résolution d’une séquence sédimentaire prélevée dans le Lac Petit (alt. 2 200 m, vallon des Millefonts, Mercantour, France) a permis d’étudier les interactions climat-environnement-Homme à l’Holocène récent en contexte de haute montagne dans les Alpes du Sud. Grâce aux analyses lithostratigraphiques, géochimiques et palynologiques, trois grandes phases ont pu être reconstituées : (1) une période de stabilité relative de l’écosystème de 4 750 à 4 350 cal. BP, caractérisée par une sédimentation lacustre dominante et des sols développés sur les versants, (2) de 4 350 à 1 550 cal. BP, une augmentation des apports érosifs contemporaine d’une dégradation des sols superficiels et du couvert forestier, (3) une phase de déstabilisation intense et définitive des versants depuis 1 550 cal. BP. Le climat a certainement joué un rôle dans la dynamique du bassin-versant, mais l’Homme, dont l’impact reste discret jusqu’à 1 550 cal. BP, pourrait être un facteur majeur de perturbation des écosystèmes du vallon des Millefonts pendant le Subatlantique. Enfin, la récurrence d’apports terrigènes pourrait témoigner d’évènements orageux de forte intensité dont les conséquences érosives ont pu être amplifiées localement par l’augmentation de la pression agro-pastorale et des activités minières.