Extension and calibration of a Hawkes-based optimal execution model

We provide some theoretical extensions and a calibration protocol for our former dynamic optimal execution model. The Hawkes parameters and the propagator are estimated independently on financial data from stocks of the CAC40. Interestingly, the propagator exhibits a smoothly decaying form with one or two dominant time scales, but only so after a few seconds that the market needs to adjust after a large trade. Motivated by our estimation results, we derive the optimal execution strategy for a multi-exponential Hawkes kernel and backtest it on the data for round trips. We find that the strategy is profitable on average when trading at the midprice, which is in accordance with violated martingale conditions. However, in most cases, these profits vanish when we take bid-ask costs into account

Élites lémovices : état des lieux de la documentation épigraphique et quelques études de cas

International audienceThis article deals with the connections between elites and territories. It is based on epigraphy in Limousin, France and includes three magistrates of the city of Lemovices and two priests of Confluent. The notion of "elite", though, goes beyond its usual political meaning and should include all the people having an eminent social position in local society.Cet article permet de réaliser un état des lieux des rapports entre élites et territoires à partir de la documentation épigraphique du Limousin. Ce corpus comporte trois magistrats de la cité des Lémovices et deux prêtres du Confluent. Cependant, le concept d’élite dépasse la seule définition politique et permet d’appréhender d’autres individus qui occupent une position éminente dans la société locale

When Gold Cations Meet Polyoxometalates

International audienceMerging gold(I) cations with polyoxometalate anions results in various interclusters and complexes. Herein, the syntheses of these newly emerging gold(I)/polyoxometalate materials are reviewed. The applications of these promising hybrids in organic catalysis are also summarized and evaluated in terms of the advantages and limitations of the catalysts including efficiency, synergistic effects and recyclability

Document d'aide au déploiement d'IPv6 sur Grid5000

Ce document présente succinctement les motivations pour l'utilisation d'IPv6 dans les grilles. Une analyse des opérations nécessaires pour son déploiement dans la plateforme Grid5000 est ensuite présentée et détaillée

Synthesis of Indolizine and Pyrrolo[1,2- a ]azepine Derivatives via a Gold(I)-Catalyzed Three-Step Cascade

International audienceLinear N-alkenyl or alkynyl N-sulfonyl 1-aminobut-3-yn-2-ones are converted into bicyclic indolizines and pyrrolo[1,2-a]azepine-type alkaloids upon gold(I) catalysis (17 examples, 10-85%). The reaction cascade allowed to form C-N, O-S and CC bonds via a cycloisomerization/sulfonyl migration/cyclization process using 10 mol % of [(2-biphenyl)di-tert-butylphosphine]gold(I) triflimide complex in dichloromethane

Regioselective Synthesis of Indene from 3-Aryl Propargylic gem -Dipivalates Catalyzed by N -Heterocyclic Carbene Gold(I) Complexes

International audience1-Aryl-3,3-bis(pivaloyloxy)propynes can be converted in good to high yields into either 1,3-or 1,2-bis(pivaloyloxy)indenes, depending on the N-heterocyclic carbene (NHC) gold(I) hexafluoroantimonate catalyst used. Almost exclusive formation of 1,3-di(oxycarbonyl)indene derivatives was achieved with cationic gold complexes containing the embracing N,N'-1,3-bis(9-butylfluorenyl)benzimidazolylidene ligand (nBu FNHC). The regioselective issue of the reaction was rationalized by the specific spatial distribution of the steric bulk in the nBu FNHC ligand. In contrast, only modest selectivities in favor of 1,2-disubstituted indenes were observed with more classical NHC gold complexes, the best selectivity being then obtained with N,N'-1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazolylidene gold chloride (SIPrAuCl) as precatalyst

Actuarial Analysis of Retirement Income Replacement Ratios

A measure of level of post-retirement standard of living is the replacement ratio, i.e., percentage of final salary received as annual retirement income derived from savings. The replacement ratio depends on many factors including salary, salary increases, investment returns, and post-retirement mortality. Elementary life contingencies techniques are used to develop a replacement ratio formula and analyze its sensitivity to these factors

Contrasting properties of particle-particle and hole-hole excitations in ²⁰⁶Tl and ²¹⁰Bi nuclei

A complete-spectroscopy investigation of low-lying, low-spin states in the one-proton-hole and one-neutron-hole nucleus 206Tl has been performed by using thermal neutron capture and γ-coincidence technique with the FIPPS Ge array at ILL Grenoble. The new experimental results, together with data for the one-proton-particle and one-neutron-particle nucleus 210Bi (taken from a previous study done at ILL in the EXILL campaign), allowed for an extensive comparison with predictions of shell-model calculations performed with realistic interactions. No phenomenological adjustments were introduced in the calculations. In 210Bi, state energies, transition multipolarities and decay branchings agree well with theory for the three well separated multiplets of states which dominate the low-lying excitations. On the contrary, in 206Tl significant discrepancies are observed: in the same energy region, six multiplets were identified, with a significant mixing among them being predicted, as a consequence of the smaller energy separation between the active orbitals. The discrepancies in 206Tl are attributed to the larger uncertainties in the determination of the off-diagonal matrix elements of the realistic shell-model interaction with respect to the calculated diagonal matrix elements, the only ones playing a major role in the case of 210Bi. The work points to the need of more advanced approaches in the construction of the realistic interactions

Integrating hydrological features and genetically validated occurrence data in occupancy modeling of an endemic and endangered semi-aquatic mammal species, Galemys pyrenaicus, in a Pyrenean catchment

As freshwater habitats are among the most endangered, there is an urgent need to identify critical areas for conservation, especially those that are home to endangered species. The Pyrenean desman (Galemys pyrenaicus) is a semi-aquatic mammal whose basic ecological requirements are largely unknown, hindering adequate conservation planning even though it is considered as a threatened species. Species distribution modelling is challenging for freshwater species. Indeed, the complexity of aquatic ecosystems (e.g., linear and hierarchical ordering) must be taken into account as well as imperfect sampling. High-quality and relevant hydrological descriptors should also be used. To understand the influence of environmental covariates on the occupancy and detection of the Pyrenean desman, we combine both a robust sign-survey data set (i.e. with genetic validation ensuring true presence information) and a hydrological model to simulate the flow regime across a whole catchment. Markovian site-occupancy analysis, taking into account sign detection and based on spatially adjacent replicates, indicated a positive influence of heterogeneity of substrate and shelters, and a negative influence of flow variability on Pyrenean desman detection. This valuable information should help to improve monitoring programs for this endangered species. Our results also highlighted a spatially clustered distribution and a positive influence of stream flow and number of tributaries on occupancy. Hence, modifications of flow regime (e.g. hydropower production, irrigation, climate change) and habitat fragmentation appear to be major threats for this species, altering the connectivity between tributaries and the mainstream river as well as between adjacent sub-catchments