Mathematical and physical ideas for climate science

The climate is a forced and dissipative nonlinear system featuring nontrivial dynamics on a vast range of spatial and temporal scales. The understanding of the climate's structural and multiscale properties is crucial for the provision of a unifying picture of its dynamics and for the implementation of accurate and efficient numerical models. We present some recent developments at the intersection between climate science, mathematics, and physics, which may prove fruitful in the direction of constructing a more comprehensive account of climate dynamics. We describe the Nambu formulation of fluid dynamics and the potential of such a theory for constructing sophisticated numerical models of geophysical fluids. Then, we focus on the statistical mechanics of quasi-equilibrium flows in a rotating environment, which seems crucial for constructing a robust theory of geophysical turbulence. We then discuss ideas and methods suited for approaching directly the nonequilibrium nature of the climate system. First, we describe some recent findings on the thermodynamics of climate, characterize its energy and entropy budgets, and discuss related methods for intercomparing climate models and for studying tipping points. These ideas can also create a common ground between geophysics and astrophysics by suggesting general tools for studying exoplanetary atmospheres. We conclude by focusing on nonequilibrium statistical mechanics, which allows for a unified framing of problems as different as the climate response to forcings, the effect of altering the boundary conditions or the coupling between geophysical flows, and the derivation of parametrizations for numerical models

(Ap)prendre sont temps

La multiplicité des points de vue, la diversité des systèmes de représentation, la réflexion critique argumentée sont les principes d’approche du réel qu’Hypothèse systématise lors de ses actions. nous voulons permettre à l’enfant l’acquisition d’un savoir utile, nécessaire à l’exercice d’un pouvoir sur son environnement. Après « Les glacières à glace naturelle » (2005), « Les moulins à eau et les centrales hydrauliques » (2006), « Fibres sous toutes les coutures ; de la matière brute aux textiles intelligents » (2007), « une brique dans le cartable » (2008), « une maison bien équipée, l’électricité et l’eau dans la maison » (2009), « voyage aux pays des sons » (2010), « Faut pas pousser... ça roule tout seul ! » (2011), « Mélanges et démélanges » (2012), « Histoire d’y voir clair ! » (2013), « graines de casserole » (2014), « Chaud...froid..., à tous les degrés ! » (2015), et « passeurs d’eau » (2016), « (Ap)prendre son temps » vient à nouveau concrétiser une approche méthodologique originale qui suscite intérêt et plaisir tout en démystifiant la position savante des sciences. « (Ap)prendre son temps » permet de poser des questions de sciences relatives au temps et à sa mesure, de rencontrer des gens de métier (horlogers) et de visiter un atelier d’horlogerie ou encore un musée. Reflet de la collaboration vécue entre enfants, enseignants et personnes ressources, cette brochure est aussi un outil qui veut donner l’envie des sciences en proposant les moyens d’en faire

126 grammes

La multiplicité des points de vue, la diversité des systèmes de représentation et la réflexion critique argumentée sont les principes d’approche du réel qu’Hypothèse systématise lors de ses actions. Nous voulons permettre à l’enfant l’acquisition d’un savoir utile, nécessaire à l’exercice d’un pouvoir sur son environnement. Après « Les glacières à glace naturelle » (2005), « Les moulins à eau et les centrales hydrauliques » (2006), « Fibres sous toutes les coutures ; de la matière brute aux textiles intelligents » (2007), « une brique dans le cartable » (2008), « une maison bien équipée, l’électricité et l’eau dans la maison » (2009), « voyage aux pays des sons » (2010), « Faut pas pousser... ça roule tout seul ! » (2011), « Mélanges et démélanges » (2012), « Histoire d’y voir clair ! » (2013), « graines de casserole » (2014), « Chaud... froid..., à tous les degrés ! » (2015), « passeurs d’eau » (2016), et « (Ap) prendre son temps » (2017), « 126 grammes » vient à nouveau concrétiser une approche méthodologique originale qui suscite intérêt et plaisir tout en démystifiant la position savante des sciences. « 126 grammes » permet de poser des questions de sciences relatives aux notions de masse et de poids et de rencontrer des gens de métier. Reflet de la collaboration vécue entre enfants, enseignants et personnes ressources, cette brochure est aussi un outil qui veut donner l’envie des sciences en proposant les moyens d’en faire

The Value of Extended Reality Techniques to Improve Remote Collaborative Maintenance Operations: A User Study

In the Architecture, Engineering and Construction (AEC) sector, data extracted from building information modelling (BIM) can be used to create a digital twin (DT). The algorithms of a BIM-based DT can facilitate the retrieval of information, which can then be used to improve building operation and maintenance procedures. However, with the increased complexity and automation of the building, maintenance operations are likely to become more complex and may require expert intervention. Collaboration and interaction between the operator and the expert may be limited as the latter may not be on site or within the company. Recently, extended reality (XR) technologies have proven to be effective in improving collaboration during maintenance operations,through data display and shared interactions. This paper presents a new collaborative solution using these technologies to enhance collaboration during remote maintenance operations. The proposed approach consists of a mixed reality (MR) set-up for the operator, a virtual reality (VR) set-up for the remote expert and a shared Digital Model of a heat exchanger. The MR set-up is used for tracking and displaying specific information, provided by the VR module. A user study was carried out to compare the efficiency of our solution with a standard audio-video collaboration. Our approach demonstrated substantial enhancements in collaborative inspection, resulting in a significative reduction in both the overall completion time of the inspection and the frequency of errors committed by the operators

Intuitive Control of Scraping and Rubbing Through Audio-tactile Synthesis

Intuitive control of synthesis processes is an ongoing challenge within the domain of auditory perception and cognition. Previous works on sound modelling combined with psychophysical tests have enabled our team to develop a synthesizer that provides intuitive control of actions and objects based on semantic descriptions for sound sources. In this demo we present an augmented version of the synthesizer in which we added tactile stimulations to increase the sensation of true continuous friction interactions (rubbing and scratching) with the simulated objects. This is of interest for several reasons. Firstly, it enables to evaluate the realism of our sound model in presence of stimulations from other modalities. Secondly it enables to compare tactile and auditory signal structures linked to the same evocation, and thirdly it provides a tool to investigate multimodal perception and how stimulations from different modalities should be combined to provide realistic user interfaces

Passeurs d'eau

La multiplicité des points de vue, la diversité des systèmes de représentation, la réflexion critique argumentée sont les principes d’approche du réel qu’Hypothèse systématise lors de ses actions. Nous voulons permettre à l’enfant l’acquisition d’un savoir utile, nécessaire à l’exercice d’un pouvoir sur son environnement. Après « Les glacières à glace naturelle » (2005), « Les moulins à eau et les centrales hydrauliques » (2006), « Fibres sous toutes les coutures ; de la matière brute aux textiles intelligents » (2007), « Une brique dans le cartable » (2008), « Une maison bien équipée, l’électricité et l’eau dans la maison » (2009), « Voyage aux pays des sons » (2010), « Faut pas pousser... ça roule tout seul ! » (2011), « Mélanges et démélanges » (2012), « Histoire d’y voir clair ! » (2013), « Graines de casserole » (2014), et « Chaud...froid..., à tous les degrés ! » (2015), « Passeurs d’eau » vient à nouveau concrétiser une approche méthodologique originale qui suscite intérêt et plaisir tout en démystifiant la position savante des sciences. « Passeurs d’eau » permet de poser des questions de sciences relatives aux bateaux, à la solidité des ponts ou au fonctionnement des écluses..., de rencontrer des gens de métier (ingénieurs, bateliers...) et de visiter un port ou une écluse afin de mieux appréhender le transport par voie fluviale. Reflet de la collaboration vécue entre enfants, enseignants et personnes ressources, cette brochure est aussi un outil qui veut donner l’envie des sciences en proposant les moyens d’en faire

The MUSE Hubble Ultra Deep Field Survey. XI. Constraining the low-mass end of the stellar mass - star formation rate relation at z < 1

Star-forming galaxies have been found to follow a relatively tight relation between stellar mass (M*) and star formation rate (SFR), dubbed the “star formation sequence”. A turnover in the sequence has been observed, where galaxies with M* <  1010 M⊙ follow a steeper relation than their higher mass counterparts, suggesting that the low-mass slope is (nearly) linear. In this paper, we characterise the properties of the low-mass end of the star formation sequence between 7 ≤ log M*[M⊙]  ≤  10.5 at redshift 0.11 <  z  <   0.91. We use the deepest MUSE observations of the Hubble Ultra Deep Field and the Hubble Deep Field South to construct a sample of 179 star-forming galaxies with high signal-to-noise emission lines. Dust-corrected SFRs are determined from Hβ λ4861 and Hα λ6563. We model the star formation sequence with a Gaussian distribution around a hyperplane between logM*, logSFR, and log(1 + z), to simultaneously constrain the slope, redshift evolution, and intrinsic scatter. We find a sub-linear slope for the low-mass regime where log SFR [M⊙yr−1] = 0.83+0.07−0.06 log M*[M⊙]+1.74+0.66−0.68 log(1 + z), increasing with redshift. We recover an intrinsic scatter in the relation of σintr = 0.44+0.05−0.04, dex, larger than typically found at higher masses. As both hydrodynamical simulations and (semi-)analytical models typically favour a steeper slope in the low-mass regime, our results provide new constraints on the feedback processes which operate preferentially in low-mass halo

Safety of psychotropic medications in pregnancy: an umbrella review

Weighing risks and benefits of the use of psychotropic medications during pregnancy remains a challenge worldwide. We systematically assessed the strength of associations between psychotropic medication use in pregnant people with mental disorders and various adverse health outcomes in both pregnant people and foetuses. Systematic reviews with meta-analyses of observational studies investigating the association between exposure to psychotropic medication in pregnancy and any adverse health outcomes were included. Credibility was graded into convincing, highly suggestive, suggestive, weak or not significant. Quality of the meta-analyses and of individual studies were assessed with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) the Newcastle-Ottawa Scale (NOS), respectively. We considered 21 meta-analyses encompassing 17,290,755 participants (AMSTAR 2 high = 1, low = 12, or critically low = 8). Evidence was suggestive for: (1) preterm birth in pregnant people with either any mental disorder (equivalent odds ratio 1.62 (95% confidence interval 1.24-2.12) or depression (1.65 [1.34-2.02]) receiving antidepressants during any trimester of pregnancy; (2) small for gestational age for pregnant people with depression receiving a SSRI during any trimester of pregnancy (1.50 [1.19-1.90]); and (3) major congenital malformation (1.24 [1.09-1.40]) or cardiac malformations (1.28 [1.11-1.47]) in babies for pregnant people with depression or anxiety receiving paroxetine during first trimester of pregnancy. Additional associations were supported by weak evidence, or were not statistically significant. This umbrella review found no convincing or highly suggestive level of evidence of adverse health outcomes associated with psychotropic medication use in pregnant people with mental disorders

Investigating ramp wave propagation inside silica glass with laser experiments and molecular simulations

Under elastic shock compression silica glass exhibits a very specific behaviour. A shock propagating inside a material is usually seen as the propagation of a discontinuity. However in silica glass, shocks are unstable and lead to the propagation of a ramp wave where the shock front becomes gradually larger over time. Ramp waves were already reported in the literature, however their origin remain uncertain. This work presents an original study combining laser shock-induced experiments and molecular dynamics simulation aiming to improve the understanding of the mechanisms involved. Experimental ramp waves were directly observed using shadowgraphy technique allowing for an estimation of the head and tail velocities. Molecular dynamics simulations were carried out in order to reproduce ramp waves and to gain insight into the material properties. Ramp waves were observed for both elastic and plastic shockwaves. In the latter case, the plastic waves were preceded by an elastic ramp precursor. The sound speed, related to the material compressibility, was found to decrease with increasing pressure, as observed experimentally for quasi-static hydrostatic loading, thus providing an explanation for the instabilities that lead to the propagation of ramp waves

Ultrasound assessments of organs and blood vessels before and after 40 days isolation in a cavern (deep time experiment 2021)

Introduction: Spaceflight simulation studies like confinement in small volume habitat with limited physical activity have reported even after 60 days an abnormal arterial wall adaptation with increase thickness or stiffness. The purpose of the current study was to determine the effects on blood vessel and organ structure of 40 days of isolation in a huge habitat with intensive physical activity.Method: Data were collected from 14 individuals (7 male) who isolated in a cavern for 40-days while performing normal daily activities without time references. Ultrasound assessments were performed pre- and post-isolation using a teleoperated system with eight different acoustic windows to obtain 19 measurements on 12 different organ/vascular structures which included the common carotid artery, femoral artery, tibial artery, jugular vein, portal vein, bile duct, kidney, pancreas, abdominal aorta, cervical and lumbar vertebral distance, and Achilles tendon.Results: Common carotid artery measures, including the intima media thickness, stiffness index, and the index of reflectivity measured from the radiofrequency signal, were not changed with isolation. Similarly, no differences were found for femoral artery measurements or measurements of any of the other organs/vessels assessed. There were no sex differences for any of the assessments.Discussion: Results from this study indicate a lack of physiological effects of 40-days of isolation in a cavern, contrary to what observed in previous 60 days confinement. This suggests a potential protective effect of sustained physical activity, or reduced environmental stress inside the huge volume of the confined facility