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Coherent excitation of the CH stretching vibrations in C2H4+ : the role of the derivative coupling studied by the Quantum Ehrenfest Method
No full textInternational audienceWe report nonadiabatic dynamics computations on C2H4+ initiated on a coherent superposition of the five lowest cationic states, employing the Quantum Ehrenfest method. In addition to the totally symmetric carbon–carbon double bond stretch and carbon-hydrogen stretches, we see that the three non-totally symmetric modes become stimulated; torsion and three different CH stretching patterns. Thus, a coherent superposition of states, of the type involved in an attochemistry experiment, leads to the stimulation of specific non-totally symmetric motions. The computations were also performed on the specific combination of the A and C states. In each case normal mode 9 (cis-asymmetric H2CCH2 stretch), out of the set of non-totally-symmetric normal modes, dominates. Thus, we can steer the nuclear motion along specific non-totally symmetric normal modes using a defined coherent superposition
Étude contrastive de l’expression linguistique du repérage spatial en français, anglais et finnois : le cas devenir, come et tulla - Amorçage de l'analyse de données
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COCOA: A compact Compton camera for astrophysical observation of MeV-scale gamma rays
No full textInternational audienceCOCOA (COmpact COmpton cAmera) is a next-generation gamma-ray telescope designed for astrophysical observations in the MeV energy range. The detector comprises a scatterer volume employing the LiquidO detection technology and an array of scintillating crystals acting as absorber. Surrounding plastic scintillator panels serve as a veto system for charged particles. The detector’s compact, scalable design enables flexible deployment on microsatellites or high-altitude balloons. Gamma rays at MeV energies have not been well explored historically (the so-called “MeV gap”) and COCOA has the potential to improve the sensitivity in this energy band
Functional Electrical Stimulation of the Plantarflexor Muscle During Walking Leads to a Proximal-to-Distal Redistribution of Lower Limb Joint Work
No full textInternational audienceObjectiveThis study aimed to compare the effects of different conditions of functional electrical stimulation (FES) applied to the ankle plantarflexor muscles (gastrocnemius, soleus, or both combined) during push-off on lower limb joint biomechanics at controlled walking speeds in healthy young adults.MethodsFifteen healthy young adults walked along a 7-meter walkway at controlled speeds under six conditions: bilateral stimulation of the soleus, gastrocnemius, both muscles combined, and matched-speed trials without stimulation. Stimulation was applied below the discomfort threshold during push-off (heel-off to toe-off of the trailing leg). Two force plates and a motion capture system measured lower limb joint biomechanics.ResultsAll FES conditions increased positive (+8%) and total mechanical work (+5%) at the ankle. FES reduced positive knee work (− 10%) and negative hip work (− 5%), although this was significant only for gastrocnemius stimulation alone or combined with soleus. The ankle’s contribution to both positive and total lower limb work increased with FES, while the contributions of the knee and hip decreased regardless of the stimulation condition. Additionally, FES increased ankle plantarflexion angle (13%) and velocity peaks (6%), without affecting spatiotemporal gait parameters at comparable speeds.ConclusionFES applied to the plantarflexor muscles during push-off leads to a proximal-to-distal redistribution of lower limb joint work during walking at controlled speeds in healthy young adults, with subtle differences depending on the stimulation condition. These findings underscore the potential of FES as a solution to redistribute lower limb joint work during walking
What a journey to the Louvre ! A study of the coevolution of artistic communities and place attendance in Paris
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Robust undulatory locomotion through neuromechanical adjustments in a dissipative medium
No full textInternational audienceDissipative environments are ubiquitous in nature, from microscopic swimmers in low-Reynolds-number fluids to macroscopic animals in frictional media. In this study, we consider a mathematical model of a slender elastic locomotor with an internal rhythmic neural pattern generator to examine various undulatory locomotion such as Caenorhabditis elegans swimming and crawling behaviours. By using local mechanical load as mechanosensory feedback, we have found that undulatory locomotion robustly emerges in different rheological media. This progressive behaviour is then characterized as a global attractor through dynamical systems analysis with a Poincaré section. Furthermore, by controlling the mechanosensation, we were able to design the dynamical systems to manoeuvre with progressive, reverse and turning motions as well as apparently random, complex behaviours, reminiscent of those experimentally observed in C. elegans. The mechanisms found in this study, together with our dynamical systems methodology, are useful for deciphering complex animal adaptive behaviours and designing robots capable of locomotion in a wide range of dissipative environments
The Sporadic Fluvial Regime of Pliva Vallis, the Outlet Valley of Jezero Crater Lake, Mars
No full textInternational audienceAbstract In situ and orbital observations have suggested that Jezero crater (field site for the Mars 2020 Perseverance rover) once hosted a paleolake fed by two inlet valleys. An outlet valley, Pliva Vallis, is present on the eastern rim of the crater and raises the question of whether the lake system operated as an open basin or as a closed basin system with one or more overflow events. To tackle this uncertainty, we present a detailed morphological study of Pliva Vallis, using digital elevation models and imagery. The atypical morphology of the valley, including reincised fluvial layered deposits, a perched valley, and bedrock incision terraces, led us to interpret that Pliva Vallis was formed by discontinuous and episodic flows rather than from a steady outlet river. These observations allowed us to infer at least four main breach episodes and propose a new scenario for the evolution of the lake system over time. We give a minimum estimate of the duration of these overflow events using a 0‐D model, simulating a valley formation by breach erosion and lake overflow. Modeling results suggest that each flood event causing a part of the incision of the outlet valley would not have lasted for more than a few weeks, and some may have lasted only a few days. These time scales are consistent with our morphological interpretation that the outlet valley was carved by discontinuous and temporary flows. In this scenario, Jezero lake was predominantly a closed basin, spilling over episodically in at least four breach events
Aging in Granulomatosis with Polyangiitis and Microscopic Polyangiitis: From Pathophysiology to Clinical Management
No full textInternational audienceAntineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) predominantly affect individuals aged 55-75 years, with granulomatosis with polyangiitis (GPA) being diagnosed most often between 55 and 65 years and microscopic polyangiitis (MPA) between 65 and 75 years. Owing to the general increase in life expectancy, the average age at diagnosis increases, encompassing also those over 75 years old. Unfortunately, the exclusion of these older patients from many clinical trials has limited our understanding of the progression of these diseases in older subjects. The role of immunosenescence and aging in AAV pathogenesis and progression is underexplored, despite potential implications in the understanding of the disease, and potentially for disease management. Although AAV manifestations are largely consistent across age groups, certain features, such as renal involvement and the association with interstitial lung disease, may be more prevalent in older patients. Frailty must be a key consideration in therapeutic decision-making, especially when balancing the efficacy of immunosuppressants with potential side effects. Recent evidence supports the use of rituximab in addition to low-dose glucocorticoids for remission induction in life-or organ-threatening AAV, including in older populations. Furthermore, preliminary evidence supports that avacopan might be as efficient as glucocorticoids in these patients. The immunosuppressive treatment of AAV reduces the immune response to environmental pathogens, with rituximab worsening age-related hypogammaglobulinemia. Thus, prophylactic measures, including vaccination and Pneumocystis pneumonia prevention, as well as strategies to mitigate glucocorticoid side effects, should be implemented in AAV management.</div
A Tertiary lymphoid structures-based pathological score predicts survival and recurrence in colorectal Cancer patients
No full textInternational audienceBackground & Aim: Colorectal cancer (CRC) is a major global health burden. The immune response within the tumor microenvironment (TME), especially the presence of tertiary lymphoid structures (TLS), plays a critical role in prognosis. However, current prognostic tools often overlook this immune component. This study aimed to characterize TLS in CRC and develop a TLS-score correlating with survival outcomes. Methods: We conducted a retrospective analysis of 7895 TLS from 806 CRC patients using data from the Finistere Registry of Digestive Tumors. Hematoxylin-eosin-saffron (HES) staining and immunohistochemistry (IHC) were employed for TLS quantification to explore their relationship with survival and recurrence metrics. Results: Patients with microsatellite instability (MSI) demonstrated higher TLS density and more mature TLS. Both TLS density and maturation showed significant correlations with overall survival (OS) and disease-free survival (DFS). Kaplan-Meier analysis revealed that increased TLS density and GC-like maturation correlated with improved OS and DFS. Our novel pathological TLS score, integrating density and maturation, effectively stratified patients by survival and recurrence risk, distinguishing high-risk individuals (score 0-1-2) with poorer outcomes from low-risk patients (score 3-4) with better prognosis (p < 0.0001), particularly in stage II-III cases. Conclusion: TLS density and maturation are robust prognostic markers in CRC. The proposed TLS score may aid pathologists in identifying patients at higher recurrence risk and poorer survival, guiding clinical decisions for monitoring and potential adjuvant therapies. Further validation of these findings is essential before clinical implementation.</div