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Search for Diffuse Supernova Neutrino Background with 956.2 days of Super-Kamiokande Gadolinium Dataset
No full textInternational audienceWe report the search result for the Diffuse Supernova Neutrino Background (DSNB) in neutrino energies beyond 9.3~MeV in the gadolinium-loaded Super-Kamiokande (SK) detector with exposure. % exposure. Starting in the summer of 2020, SK introduced 0.01\% gadolinium (Gd) by mass into its ultra-pure water to enhance the neutron capture signal, termed the SK-VI phase. This was followed by a 0.03\% Gd-loading in 2022, a phase referred to as SK-VII. We then conducted a DSNB search using 552.2~days of SK-VI data and 404.0~days of SK-VII data through September 2023. This analysis includes several new features, such as two new machine-learning neutron detection algorithms with Gd, an improved atmospheric background reduction technique, and two parallel statistical approaches. No significant excess over background predictions was found in a DSNB spectrum-independent analysis, and 90\% C.L. upper limits on the astrophysical electron anti-neutrino flux were set. Additionally, a spectral fitting result exhibited a disagreement with a null DSNB hypothesis, comparable to a previous result from 5823~days of all SK pure water phases
Longest increasing subsequences for distributions with atoms, and an inhomogeneous Hammersley process
No full textA famous result by Hammersley and Versik-Kerov states that the length of the longest increasing subsequence among iid continuous random variables grows like . We investigate here the asymptotic behavior of for distributions with atoms.For purely discrete random variables, we characterize the asymptotic order of through a variational problem and provide explicit estimates for classical distributions. The proofs rely on a coupling with an inhomogeneous version of the discrete-time continuous-space Hammersley process. This reveals that, in contrast to the continuous case, the discrete setting exhibits a wide range of growth rates between and , depending on the tail behavior of the distribution. We can then easily deduce the asymptotics of for a completely arbitrary distribution
Inf-sup stable non-conforming finite elements on tetrahedra with second and third order accuracy
No full textWe introduce a family of scalar non-conforming finite elements with second and third order accuracy with respect to the -norm on tetrahedra. Their vector-valued versions generate, together with discontinuous pressure approximations of order one and two respectively, inf-sup stable finite element pairs with convergence order two and three for the Stokes problem in energy norm
Extrapolation of Tempered Posteriors
No full textInternational audienceTempering is a popular tool in Bayesian computation, being used to transform a posterior distribution p 1 into a reference distribution p 0 that is more easily approximated. Several algorithms exist that start by approximating p 0 and proceed through a sequence of intermediate distributions p t until an approximation to p 1 is obtained. Our contribution reveals that high-quality approximation of terms up to p 1 is not essential, as knowledge of the intermediate distributions enables posterior quantities of interest to be extrapolated. Specifically, we establish conditions under which posterior expectations are determined by their associated tempered expectations on any non-empty t interval. Harnessing this result, we propose novel methodology for approximating posterior expectations based on extrapolation and smoothing of tempered expectations, which we implement as a post-processing variance-reduction tool for sequential Monte Carlo.52 pages, 10 figure
Survey of the updated Oxygen line list in the HITRAN2024 spectroscopic database
No full textInternational audienc
Collision induced absorption in HITRAN2024: Enhanced and improved data for atmospheric and planetary studies
No full textInternational audienceCollision-Induced Absorption (CIA) phenomena play a key role in the atmospheric energy balance, making their accurate parametrization a decisive factor in modeling planetary atmospheres. This is the primary reason why the HITRAN spectroscopic database includes a dedicated section for CIAs. This section became available for the first time in 2012, followed by its first update in 2019. Six years since the first update, and with a significant amount of new data now available, it is timely to issue a second update. In this update, new data regarding collisional pairs that appear in the CIA section for the first time ( N2–Ar, and CO2– H2O) are presented. Concerning collisional pairs already present in the database, new data extending both spectral and temperature ranges are available for CO2– CO2, CO2– H2, CO2– CH4, H2– N2, O2– O2, and O2– CO2, while new experimental data about H2– H2 and H2–He have been included alongside the respective theoretical calculations. Data sources, comparisons among different data, and selection criteria, are discussed in detail. The final section is focused on identifying the CIA data that would be most valuable for the planetary science and astrophysics community in the future
Deep-lying semi-Dirac fermions in hexagonal close-packed cadmium
No full textInternational audienceAbstract Semi-Dirac fermions are massless in one direction and massive in the perpendicular directions. Such quasiparticles have been proposed in various contexts in condensed matter. Using first principles calculations, we identify a pair of semi-Dirac bands anti-crossing at −3 eV below the Fermi level in the electronic structure of hexagonal close-packed cadmium. The linear out-of-plane dispersion is kept up to the Fermi level. We demonstrate that the dichotomy between the linear and quadratic dispersions is driven by an orientation-sensitive hybridization between the s and p z orbitals. The upper semi-Dirac band produces a lens-shaped nonellipsoidal Fermi sheet whose cross-section area has a k -dependence that is in excellent agreement with the experimentally measured period of Sondheimer oscillations
Towards annual updating of forced warming to date and constrained climate projections
No full textInternational audienceAbstract In the context of rapid human-caused climate change, regular updates of the state of knowledge of current and future climate are needed. New statistical methods using observational constraints underpinned estimates of present-day human-induced warming and projected future warming in the most recent IPCC report. As time goes by, and new updated observational records become available, how should estimates of the current and projected human-caused climate change be updated? Here, we use a perfect model framework and show that incorporating observations from every new year in observationally constrained projections improves their accuracy, without causing major year-to-year spurious variability on outcomes. The forced warming estimated for the current year also exhibits high enough stability to be considered as a robust indicator of the state of the climate system
On the Localization of the Bergman Kernel and applications to Toeplitz theory
No full textFor a compact complex manifold endowed with a big line bundle and a Radon measure, we study the localization phenomena of the associated Bergman (or Christoffel-Darboux) kernel. For Bernstein-Markov measures, this results in the determination of the limiting off-diagonal Bergman measure, thereby confirming a conjecture of Zelditch. We then turn to applications in the theory of Toeplitz operators, showing in particular that they form an algebra under composition. Building on this, we then show that for Bernstein-Markov measures, the spectrum of Toeplitz operators equidistributes.</div
Mechanism of Arp2/3 complex branch disassembly by human Coro7
No full textInternational audienceArp2/3 complex nucleates branched actin networks that drive cell motility and intracellular trafficking. Coronins, a family of seven proteins in humans, inhibit Arp2/3 complex in vitro and reduce branch density in cells. Coro7, a distant member of this family, features two β-propeller domains (β1β2) and C-terminal Central-Acidic (CA) domains and remains poorly studied. Here, cryo-EM and biochemical data show that CA binds subunit Arp3 of free Arp2/3 complex with ~1 µM affinity, inhibiting polymerization like Arpin, while displacing Arp3’s autoinhibitory C-terminal tail and promoting the active, short-pitch conformation, like WASP-family nucleation-promoting factors. Full-length Coro7, however, does not inhibit Arp2/3 complex polymerization but effectively induces debranching, whereas the isolated β1β2 or CA domains do not. In cells, Coro7 depletion disrupts ER-Golgi transport, which is rescued by full-length Coro7 but not by truncated variants. These results suggest that Coro7 functions as an Arp2/3 complex branch disassembly factor implicated in actin-dependent ER-Golgi trafficking