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New line list for the ν4 bands of the trans (790.117 cm–1) and cis (851.943 cm–1) conformers of nitrous acid (HONO): Accurate positions and absolute intensities
No full textInternational audienceThe goal of this work was to update and significantly improve the line lists that have been generated recently for 11 µm bands of the trans- and cis- conformer forms of nitrous acid (HONO) [Armante R, Perrin A, Kwabia Tchana F, Manceron L. The ν4 bands at 11 μm: linelists for the trans- and cis- conformer forms of nitrous acid (HONO) in the 2019 version of the GEISA database. Molecular Physics 2021;120:e1951860]. That 2019 version of the 11 µm line list was generated using the spectroscopic parameters that were available, at that time, in the literature. During the present study, we used high-resolution Fourier transform spectra recorded at 11 µm to perform a large investigation of line positions and intensities for the ν4 bands of the trans- and cis-conformer of HONO. The resulting set of experimental ν4 (absolute) intensities and of 41 energy levels were used to determine, by least squares fit computations, improved position and intensity parameters for the ν4 bands of the trans- and cis-conformer of HONO. For trans-HONO, the ν4 band appeared not to be perturbed, while for cis-HONO a weak high order B-type Coriolis, coupling together the 41 and 61 energy levels was evidenced for the first time. This new list is of potential interest for the IASI-NG (Infrared Atmospheric Sounding Interferometer - New Generation) instrument which will be launched on board the METOP-SG satellite in 2025
Identify the most influential employees in Covid-19 Pandemic by A stochastic MILP influence maximization
No full textInternational audienceManagers seek ways to survive pandemic situations to avoid huge financial losses. Preventing staff from infecting each other plays a prominent role in survival. To do so, the infectious among employees should be modeled at first. Secondly, the members who directly or indirectly infect the maximum number of other employees are identified. This problem is considered as an instance of Influence Maximization (IM) general problems. We use a Mixed Integer Linear Program (MILP) analytical optimization for IM problem. The MILP optimization guarantees the global optimal solution. However, due to the uncertain nature of influence, the IM problem is formulated as a stochastic optimization based on a limited number of scenarios. Therefore, the whole stochastic nature of the influence process may not be captured.It is of high importance to check whether the number of scenarios used in stochastic MILP is adequate. To do so, the result of the optimization is simulated with numerous scenarios to evaluate the gap between the objective function and the exact expected value. The proposed stochastic MILP methodology is examined on a company with twelve employees. The efficiency of the method and adequacy of scenarios are then discussed
Measurement of the polarizations of prompt and non-prompt J/ and (2S) mesons produced in pp collisions at = 13 TeV
No full textInternational audienceThe polarizations of prompt and non-prompt J and (2S) mesons are measured in proton-proton collisions at = 13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 fb. Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, , is measured as a function of the transverse momentum, , of the charmonium states, in the 25-120 and 20-100 GeV ranges for the J and (2S), respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for 25 GeV, the non-prompt J and (2S) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for exceeding 30 times the J mass, where tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at = 7 TeV, the prompt polarizations show a significant variation with , at low
Anthropogenic climate change will intensify European explosive storms similar to Alex, Eunice, and Xynthia in the future
No full textInternational audienceExtratropical storms, particularly explosive storms or ’weather bombs’ with exceptionally high deepening rates, present substantial risks and are susceptible to climate change. Individual storms may exhibit a complex and hardly detectable response to human-driven climatechange because of the atmosphere’s chaotic nature and variability at regional level. It is thus essential to understand changes in specific storms for building local resilience and advancing our overall comprehension of storm trends. To address this challenge, this study performs future projections for three specific explosive storms, each impacting different European locations: Alex (October 2020), Eunice (January 2022), and Xynthia (February 2010). Using a dataset of 105 members from the Community Earth System Model version 1 (CESM1), we identify analogues —storms with a similar development stage— in two periods: the present-day climate (1991-2001) and a future climate scenario characterized by high anthropogenic greenhouse gas emissions (RCP8.5, 2091-2101). We evaluate trends in the frequency of occurrence of the storms and intensity, as well as on climate drivers of impacts and the underlying dynamics. For all storms, our analysis reveals an increase in precipitation and wind speed in the analogues of the future climate, specially for the explosive ones. These findings underscore the potential consequences of explosive storms modified by climate change and their subsequent impacts on various regions of Europe, offering evidence that can be used to prepare and enhance adaptation processe
Radiative-convective models of the atmospheres of Uranus and Neptune: heating sources and seasonal effects
No full textInternational audienceThe observations made during the Voyager 2 yby have shown that the stratosphere of Uranus and that of Neptune are warmer than expected by previous models. In addition, no seasonal variability of the thermal structure has been observed on Uranus since Voyager 2 era and signi cant subseasonal variations have been revealed on Neptune.Aims. In this paper, we evaluate different realistic heat sources that can induce suf cient heating to warm the atmosphere of these planets and we estimate the seasonal effects on the thermal structure.Methods. The seasonal radiative-convective model developed by the Laboratoire de Météorologie Dynamique was used to reproduce the thermal structure of these planets. Three hypotheses for the heating sources were explored separately: aerosol layers, a higher methane mole fraction, and thermospheric conduction.Results. Our modelling indicates that aerosols with plausible scattering properties can produce the requisite heating for Uranus, but not for Neptune. Alternatively, greater stratospheric methane abundances can provide the missing heating on both planets, but the large values needed are inconsistent with current observational constraints. In contrast, adding thermospheric conduction cannot warm the stratosphere of both planets alone. The combination of these heat sources is also investigated. In the upper troposphere of both planets, the meridional thermal structures produced by our model are found inconsistent with those retrieved from Voyager 2/IRIS data. Furthermore, our models predict seasonal variations should exist within the stratospheres of both planets while observations showed that Uranus seems to be invariant to meridional contrasts and only subseasonal temperature trends are visible on Neptune. However, a warm south pole is seen in our simulations of Neptune as observed since 2003
Final-state interactions in neutrino-induced proton knockout from argon in MicroBooNE
No full textInternational audienceNeutrino event generators make use of intranuclear cascade models (INCs), to predict the kinematics of hadrons produced in neutrino-nucleus interactions. We perform a consistent comparison of different INCs, by using the same set of events as input to the NEUT, NuWro, Achilles and INCL INCs. The inputs correspond to calculations of the fully differential single-proton knockout cross section, either in the distorted-wave impulse approximation (DWIA) or plane-wave impulse approximation (PWIA), both including realistic nuclear hole spectral functions. We compare the INC results to DWIA calculations with an optical potential, used extensively in the analysis of (e,e'p) experiments. We point out a systematic discrepancy between both approaches. We apply the INC results to recent MicroBooNE data. We assess the influence of the choice of spectral function, finding that large variations in realistic spectral functions are indistinguishable with present data. The data is underpredicted, with strength missing in the region where two-nucleon knockout and resonance production contribute. However, the data is underpredicted also in regions of low transverse missing momentum, where one-nucleon knockout dominates. The inclusion of the interference with two-body currents could lead to additional strength in this region
Comparison between non orographic gravity wave parameterizations used in QBOi models and Strateole 2 constant level balloons
No full textInternational audienceGravity Wave (GW) parameterizations from 12 General Circulation Models (GCMs) participating in the Quasi-Biennial Oscillation initiative (QBOi) are compared to Strateole-2 balloon observations made in the tropical lower stratosphere from November 2019 to February 2020 (phase 1) and from October 2021 to January 2022 (phase 2). The parameterizations employ the 3 standard techniques used in GCMs to represent subgrid scale non-orographic GWs, namely the two globally spectral techniques developed by Warner and McIntyre (1999) and Hines {1997), as well as the "multiwaves" approaches following Lindzen (1981). The input meteorological fields necessary to run the parameterizations offline are extracted from the ERA5 reanalysis and correspond to the meteorological conditions found underneath the balloons. In general, there is fair agreement between amplitudes derived from measurements for the waves with periods less than hr and the parameterizations. The correlation between the daily observations and the corresponding results of the parameterization can be around , which is significant since 1200 days of observations are used. Given that the parameterizations have only been tuned to produce a QBO in the models, the correlation coefficient of the GW momentum fluxes is surprisingly good. These correlations nevertheless vary between schemes and depend little on their formulation (globally spectral versus multiwaves for instance). We therefore attribute these correlations to dynamical filtering, which all schemes take into account, whereas only a few relate the gravity waves to their sources. Statistically significant correlations are mostly found for eastward propagating waves, which may be due to the fact that during both Strateole 2 phases the QBO is easterly at the altitude of the balloon flights. We also found that the probability density functions (pdfs) of the momentum fluxes are better represented in spectral schemes with constant sources than in schemes ("spectral" or "multiwaves") that relate GWs to their convective sources
Elastic Instability behind Brittle Fracture
No full textInternational audienceWe argue that nucleation of brittle cracks in initially flawless soft elastic solids is preceded by a nonlinear elastic instability, which cannot be captured without accounting for geometrical precise description of finite elastic deformation. As a prototypical problem we consider a homogeneous elastic body subjected to tension and assume that it is weakened by the presence of a free surface which then serves as a site of crack nucleation. We show that in this maximally simplified setting, brittle fracture emerges from a symmetry breaking elastic instability activated by softening and involving large elastic rotations. The implied bifurcation of the homogeneous elastic equilibrium is highly unconventional for nonlinear elasticity as it exhibits an extraordinary sensitivity to geometry, reminiscent of the transition to turbulence in fluids. We trace the post-bifurcational development of this instability beyond the limits of applicability of scale free continuum elasticity and use a phase-field approach to capture the scale dependent sub-continuum strain localization, signaling the formation of actual cracks
Global characterization of a laser-generated neutron source
No full textInternational audienceLaser-driven neutron sources are routinely produced by the interaction of laser-accelerated protons with a converter. They present complementary characteristics to those of conventional accelerator-based neutron sources (e.g. short pulse durations, enabling novel applications like radiography). We present here results from an experiment aimed at performing a global characterization of the neutrons produced using the Titan laser at the Jupiter Laser Facility (Livermore, USA), where protons were accelerated from 23µm thick plastic targets and directed onto a LiF converter to produce neutrons. For this purpose, several diagnostics were used to measure these neutron emissions, such as CR-39, activation foils, time-of-flight detectors and direct measurement of 7Be residual activity in the LiF converters. The use of these different, independently operating diagnostics enables comparison of the various measurements performed to provide a robust characterization. These measurements led to a neutron yield of 2.0x10 9 neutrons per shot with a modest angular dependence, close to that simulated
RNA inverse folding can be solved in linear time for structures without isolated stacks or base pairs
No full textInternational audienceInverse folding is a classic instance of negative RNA design which consists of finding a sequence that uniquely folds into a target secondary structure with respect to energy minimization. A breakthrough result of Bonnet et al shows that, even in simple base pairs-based (BP) models, the decision version of a mildly constrained version of inverse folding is NP-hard. In this work, we show that inverse folding can be solved in linear time for every target structure that contains no isolated BP and no isolated stack BP. (i.e. when helices have all sizes more than ).For structures featuring shorter helices, our linear algorithm is no longer guaranteed to produce a solution, but still does so for a large proportion of instances.Our approach introduces a notion of modulo -separability, generalizing a property introduced by Hales et al. Separability is a sufficient condition for the existence of a solution to the inverse folding problem. We show that, for any input secondary structure of length , a modulo -separated sequence can be produced in time anytime such a sequence exists. Meanwhile, we show that any structure such that is either trivially non-designable, or always admits a modulo- separated sequence (). Solution sequences can thus be produced in linear time, and even be uniformly generated within the set of modulo- separable sequences