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Multivariate Self-Exciting Processes with Dependencies
No full textThis paper introduces the class of multidimensional self-exciting processes with dependencies (MSPD), which is a unifying writing for a large class of processes: counting, loss, intensity, and also shifted processes. The framework takes into account dynamic dependencies between the frequency and the severity components of the risk, and therefore induces theoretical challenges in the computations of risk valuations. We present a general method for calculating different quantities related to these MSPDs, which combines the Poisson imbedding, the pseudo-chaotic expansion and Malliavin calculus. The methodology is illustrated for the computation of explicit general correlation formula
A Global High-Resolution Hydrological Model to Simulate the Dynamics of Surface Liquid Reservoirs: Application on Mars
No full textSurface runoff shapes planetary landscapes, but global hydrological models often lack the resolution and flexibility to simulate dynamic surface water bodies beyond Earth. Recent studies of Mars have revealed abundant geological and mineralogical evidence for past surface water, including valley networks, crater lakes, deltas and possible ocean margins dating from late Noachian to early Hesperian times. These features suggest that early Mars experienced periods allowing liquid water stability, runoff and sediment transport. To investigate where surface water could accumulate and how it may have been redistributed, we developed a global high-resolution (km-scale) surface hydrological model. The model uses a pre-computed hydrological database that maps topographic depressions, their spillover points, hierarchical connections between basins, and lake volume-area-elevation relationships. This database approach greatly accelerates simulations by avoiding repeated geomorphic processing. The model dynamically forms, grows, merges and dries lakes and putative seas without prescribing fixed coastlines, by transferring water volumes between depressions according to their storage capacities and overflow rules. We explore model behavior over the present-day Mars' topography measured by MOLA (Mars Orbiter Laser Altimeter) topography for a range of evaporation rates and total water inventories expressed as Global Equivalent Layer (GEL). Simulations are iterated to steady state under the assumption that precipitation balances evaporation plus overflow. The model outputs the extent and depth of surface water bodies and identifies main drainage pathways using overflow fluxes as runoff indicators. Results show a transition toward a contiguous northern ocean between low (1–10 m) GEL values and increasing concentration of water in northern lowlands and major impact basins at higher GEL. We discuss the model's limitations, including its dependence on topography and the absence of subsurface flows, and propose future improvements. This framework provides a quantitative tool to link preserved geomorphology with plausible past hydrological states. Future work will couple the model with a 3D global climate model into a Planetary Evolution Model (PEM) to study transient water redistribution and climate-hydrology feedbacks
Family Institutions and the Global Fertility Transition
No full textInternational audienceMuch of the observed cross-country variation in fertility aligns with the predictions of classic theories of the fertility transition: countries with higher levels of human capital, higher GDP per capita, or lower mortality rates tend to exhibit lower fertility. However, when examining changes within countries over the past 60 years, larger fertility declines are only weakly associated with greater improvements in human capital, per capita GDP, or survival rates. To understand why, we focus on the role of family institutions, particularly marriage and inheritance customs. We argue that, together with the diffusion of cultural norms, they help explain variations in the timing, speed and magnitude of the fertility decline. We propose a stylized model integrating economic, health, institutional and cultural factors to study how these factors interact to shape fertility transition paths. We find that family institutions can mediate the effect of economic development by constraining fertility responses
Measurement of the local and nonlocal amplitudes in decays
No full textInternational audienceThis paper presents a thorough study of the local and nonlocal amplitudes in transitions through an amplitude analysis of the dimuon mass spectrum of the decay. The analysis is based on collision data corresponding to an integrated luminosity of 8.4fb collected by the LHCb experiment. This measurement employs a model that describes both one-particle and two-particle nonlocal amplitudes across the entirety of the dimuon mass spectrum, enabling the determination of both short- and long-distance contributions to the decay. The compatibility of the Wilson coefficient combinations and with the Standard Model prediction is found to vary between and , depending on the choice of local form factors
First measurement of time-dependent violation in the flavor-changing neutral-current decay
No full textInternational audienceA flavor-tagged time-dependent analysis of decays is performed across the full dimuon mass range excluding the and resonance regions. The analysis uses proton-proton collision data collected by the LHCb experiment in 2011--2018 at center-of-mass energies of 7, 8 and 13TeV, corresponding to an integrated luminosity of 9. The CP violation parameters are determined to be and , where the first uncertainties are statistical and the second are systematic. The results are consistent with the Standard Model prediction. This is the first experimental study of time-dependent CP violation in processes
Hardness of some optimization problems over correlation polyhedra
No full textWe prove the NP-hardness, using Karp reductions, of some problems related to the correlation polytope and its corresponding cone, spanned by all of the n × n rank-one matrices over {0, 1}. The problems are: membership, rank of the decomposition, and a "relaxed rank" obtained from relaxing the zero-norm expression for the rank to an ℓ1 norm. While membership and rank are natural problems for any matrix cone, the relaxed rank problem occurs in some signal processing and statistical applications.</div
Intergenerational Mobility of Immigrants in 15 Destination Countries
No full textWe estimate intergenerational mobility of immigrants and their children in fifteen receiving countries. We document large income gaps for first-generation immigrants that diminish in the second generation. Around half of the second-generation gap can be explained by differences in parental income, with the remainder due to differential rates of absolute mobility. The daughters of immigrants enjoy higher absolute mobility than daughters of locals in most destinations, while immigrant sons primarily enjoy this advantage in countries with long histories of immigration. Cross-country differences in absolute mobility are not driven by parental country-of-origin, but instead by destination labor markets and immigration policy
Mean stress effects and energy-based modeling of fatigue behavior in artificially cemented rock-like materials under cyclic loading
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Bringing contact interventions to the lab: Effects of brief bilateral discussions on interethnic trust in Senegal
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Relativistic Feedback Discharges in Dielectric Solids
No full textInternational audienceThe photoelectric feedback processes leading to growth of relativistic runaway electron avalanches are believed to be responsible for extreme uxes of gamma rays produced from very compact regions of space with dimensions on the order of hundred meters in association with lightning activity in the Earths natural environment (Pasko et al., 2025, https://doi.org/10.1029/2025JD043897). Here we demonstrate for the rst time that the same photoelectric feedback discharges can be realized on centimeter scales in common solid state dielectric materials, like quartz, acrylic and bismuth germanate. These discharge can serve as new sources of high energy X-ray radiation