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GWTC-4.0: An Introduction to Version 4.0 of the Gravitational-Wave Transient Catalog
No full textInternational audienceThe Gravitational-Wave Transient Catalog (GWTC) is a collection of short-duration (transient) gravitational wave signals identified by the LIGO-Virgo-KAGRA Collaboration in gravitational-wave data produced by the eponymous detectors. The catalog provides information about the identified candidates, such as the arrival time and amplitude of the signal and properties of the signal's source as inferred from the observational data. GWTC is the data release of this dataset and version 4.0 extends the catalog to include observations made during the first part of the fourth LIGO-Virgo-KAGRA observing run up until 2024 January 31. This paper marks an introduction to a collection of articles related to this version of the catalog, GWTC-4.0. The collection of articles accompanying the catalog provides documentation of the methods used to analyze the data, summaries of the catalog of events, observational measurements drawn from the population, and detailed discussions of selected candidate
Les grottes François Ier à Aiguebelette (Savoie) - Un exemple de grotte bergerie médiévale ?
No full textInternational audienceDeux cavités mitoyennes installées à 870 m d’altitude sur un chainon du Jura méridional qui domine le lac d’Aiguebelette (Savoie) ont récemment fait l’objet de petits sondages manuels. Les résultats suggèrent qu’elles ont abrité des activités différenciées que le mobilier (monnaies et céramiques) et des datations radiocarbone permettent de positionner entre l’Antiquité tardive et le Moyen Âge central. La présence dans la cavité nord la plus spacieuse d’une accumulation de sédiments cendro-charbonneux fins suggère l’hypothèse d’une grotte bergerie. Bien que l’analyse des phytolithes n’ait pas livré d’argument décisif, les spectres fauniques très majoritairement constitués d’animaux domestiques viennent soutenir cette proposition. Dans le même temps, la cavité sud pourrait être dévolue à des activités annexes plus diversifiées. De futures recherches plus poussées sur ces grottes jumelles permettraient de mieux connaitre les pratiques pastorales de la première moitié du Moyen Âge, dans l’avant-pays savoyard
Who Killed Blessing Matthew at the Franco–Italian Border? Framing Responsibility through an Analysis of the Entanglement of Law and Space
No full textInternational audienceThis paper analyzes the “kill chain” that led to the death of Blessing Matthew, a young Nigerian woman who tried to cross the Franco–Italian Alpine border, in May 2018. It aims to deconstruct the entanglement of laws, regulations, and practices at this borderland, so as to position Matthew’s case within the broader migration and border regime and thus overcome the rhetoric of inevitability and discourse attributing the young woman’s death to the dangers of the mountain environment. The paper highlights a discrepancy between orders and practices, through a critical analysis of the mission order received by the police forces that were deployed to the border region at the time of Matthew’s death, placing responsibility on the officers who were patrolling the border zone. It also points to the liability of senior government officials in giving contradictory orders as well as to the ambiguity of the state-determined rules governing border crossings and controls
Synthèse in-situ de composites à matrice métallique par fusion laser sur lit de poudre
No full textInternational audienceLa synthèse in-situ des Composites à Matrice Métallique (CMM) par la méthode de Synthèse Réactive Globale (GRS) est une approche prometteuse pour contrôler la taille et la distribution des renforts, ainsi que pour obtenir une interface nette, en l’absence d’interphase due à la réactivité chimique. A partir de précurseurs chimiques commerciaux, la GRS permet de former in-situ à la fois la matrice et le renfort du CMM selon les équilibres entre phases du système thermodynamique choisi. Les CMM obtenus sont de géométries simples (cylindres ou plaques). Elle a été appliquée avec succès aux CMM conventionnels tels que Al-TiC [1] ou AlTiB₂. Les travaux de Samer et al. [2] ont également abouti à l’obtention du CMM Al-Tau3, où Tau3 est un borocarbure ternaire (Al3B48C2). Ce matériau, intéressant pour ses propriétés structurales et d’absorption neutronique, ne présente pas les problématiques de mise en œuvre et de réactivité du CMM Al-B4C, avec une répartition homogène et la possibilité de fort taux de renforts (Figure 1) [3]. Plus récemment, la GRS de l'CMM Al-Tau3 a été transposée à la technique de fabrication additive par fusion laser sur lit de poudre (LPBF) afin d'obtenir des formes proches des dimensions finales et des géométries complexes, tout en synthétisant le CMM in-situ, au cours du procédé LPBF [4]. Les microstructures complexes (Figure 2) sont un défi pour la compréhension des mécanismes de synthèse in-situ, influencés par les températures atteintes, les gradients de température, ainsi que les cinétiques de chauffe et de refroidissement. Nous proposons de détailler ces microstructures en termes de nature de phases formées, taille et morphologie ; et de discuter de l'influence des différents paramètres comme le nombre de passes laser, la vitesse de déplacement du laser ou la composition initiale des précurseurs
Performance of heavy-flavour jet identification in Lorentz-boosted topologies in proton-proton collisions at = 13 TeV
No full textInternational audienceMeasurements in the highly Lorentz-boosted regime provoke increased interest in probing the Higgs boson properties and in searching for particles beyond the standard model at the LHC. In the CMS Collaboration, various boosted-object tagging algorithms, designed to identify hadronic jets originating from a massive particle decaying to or , have been developed and deployed across a range of physics analyses. This paper highlights their performance on simulated events, and summarizes novel calibration techniques using proton-proton collision data collected at = 13 TeV during the 20162018 LHC data-taking period. Three dedicated methods are used for the calibration in multijet events, leveraging either machine learning techniques, the presence of muons within energetic boosted jets, or the reconstruction of hadronically decaying high-energy Z bosons. The calibration results, obtained through a combination of these approaches, are presented and discussed
Eccentric Hamstring Torque Production and Muscle Activity in Unassisted Versus Assisted Nordic Hamstring Exercises
No full textInternational audienceThe aim of this study was to compare hamstrings eccentric torque production and muscle activities during one maximal repetition of conventional unassisted ( C NHE) and assisted ( A NHE) Nordic Hamstring Exercise. Twelve participants randomly performed 5 different NHE variations at maximal intensity. We calculated maximal hamstring eccentric torque production ( T max ), torque time integral, root mean square at T max , and electromyography integral for 7 muscles during exercises. C NHE resulted in lower T max and torque time integral ( P < .05) compared with A NHEs. Moreover, it exhibited lower electromyography integral for the biceps femoris , semitendinous , gastrocnemius lateralis , and gastrocnemius medialis ( P < .05). Unilateral A NHE simulating the late-swing phase of the step cycle ( A NHELS U ) demonstrated greater T max compared with bilateral and unilateral A NHE ( P < .01), whereas root mean square at T max was lower during A NHELS U than bilateral A NHE ( P < .05). The increased eccentric torque production and higher muscle activities during A NHE could be attributed to greater muscle length at the end of the movements and a longer time under tension. Our results suggest that (1) A NHE increases hamstrings torque production and muscle activities of the knee flexors compared with C NHE, and (2) A NHELS U is the only variation specific to the injury kinematics that maximizes overall eccentric torque production
At the crossroads between astronomy and ecology: exploring links between urban skyglow and nocturnal bird migration
No full textInternational audienceThis study investigates the impact of urban skyglow on nocturnal bird migration by combining night sky brightness measurements and acoustic monitoring in the Grenoble basin. Using photometric sensors and bioacoustic recorders, we tracked the spring migration of the Black-crowned Night Heron (Nycticorax nycticorax) across two urban sites. Preliminary results show no clear effect of night sky brightness on migratory activity, though temporal patterns linked to night progress and seasonality were evident. Methodo- logical limitations and behavioral biases are discussed, with perspectives for integrating radar data in future works
Measurement of the cross-sections as a function of the muon transverse momentum in collisions at 5.02 TeV
No full textInternational audienceThe cross-sections are measured at a proton-proton centre-of-mass energy TeV using a dataset corresponding to an integrated luminosity of 100 pb recorded by the LHCb experiment. Considering muons in the pseudorapidity range , the cross-sections are measured differentially in twelve intervals of muon transverse momentum between GeV. Integrated over , the measured cross-sections are \begin{align*} σ_{W^+ \to μ^+ ν_μ} &= 300.9 \pm 2.4 \pm 3.8 \pm 6.0~\text{pb}, \\ σ_{W^- \to μ^- \barν_μ} &= 236.9 \pm 2.1 \pm 2.7 \pm 4.7~\text{pb}, \end{align*} where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine the -boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields \begin{align*} m_W = 80369 \pm 130 \pm 33~\text{MeV}, \end{align*} where the first uncertainty is experimental and the second is theoretical
Induced polarization of volcanic rocks. 9. Anatomy of a rising thermal plume
No full textInternational audienceThe dynamic Stern layer petrophysical model can be used to interpret field induced polarization data and can be applied to both magmatic (volcanic and igneous) rocks and sediments. Thanks to it, field-scale tomograms of conductivity and normalized chargeability can be transformed into tomograms of porosity, Cation Exchange Capacity (CEC) and temperature. Fur ther more, kilometer-scale galvanometric induced-polarization surveys are nowadays doable thanks to the recent development of independent stations measuring the primary and secondary electrical fields. This approach reduces capacitive and inductive coupling effects inherent to systems based on long cables and allow for deeper investigations. We apply here this combined methodology (novel equipment and revised petrophysical model) to a geothermal prospect located at Mashyuza, Republic of Rwanda, in Eastern Africa. At this site, the rifting activity led to the occurrence of an extensional regime favouring the occurrence of a rising thermal plume at the intersection between two faults. The existence of this plume is expressed at the ground surface by the presence of a hot spring at a temperature of ∼52 • C (a well nearby provides a temperature of ∼65 • C). A time-domain large-scale induced polarization survey is performed. The current source signal is produced by a VIP-5000 squared signal injector and injection current values range from 1 to 4 A, with stacking of 1 s on-off signals ranging from 100 to 300 stacks to improve the signal-to-noise ratio. The size of the 3-D array is ∼1.5 km and allows a tomography down to a depth of ∼300 m. The data are inverted with the deterministic least-square technique, penalizing the roughness of the resulting tomograms. The conductivity and normalized chargeability tomograms are combined to get the temperature, porosity and CEC distributions. The temperature distribution is consistent with the temperature of the hot spring and well. The results are interpreted in terms of ground water flow pattern and dilution of the mineralized thermal water with the fresher surface meteoric water. The survey images a rising plume of warm water from a depth of at least 300 m along intersecting fracture systems