Halo Occupation Distribution of Emission Line Galaxies: fitting method with Gaussian Processes

The halo occupation distribution (HOD) framework is an empirical method to describe the connection between dark matter halos and galaxies, which is constrained by small scale clustering data. Efficient fitting procedures are required to scan the HOD parameter space. This paper describes such a method based on Gaussian Processes to iteratively build a surrogate model of the posterior of the likelihood surface from a reasonable amount of likelihood computations, typically two orders of magnitude less than standard Monte Carlo Markov chain algorithms. Errors in the likelihood computation due to stochastic HOD modelling are also accounted for in the method we propose. We report results of reproducibility, accuracy and stability tests of the method derived from simulation, taking as a test case star-forming emission line galaxies, which constitute the main tracer of the Dark Energy Spectroscopic Instrument and have so far a poorly constrained galaxy-halo connection from observational data

Wide awake local anaesthesia no tourniquet : a review of current concepts

BACKGROUND : Wide awake local anaesthesia no tourniquet (WALANT) is a local anaesthetic technique that employs lignocaine combined with adrenaline to maintain a pain-free and bloodless field during surgery on an awake patient, without the use of a tourniquet. METHODS : This article is a narrative review of the literature on the use of this mode of anaesthesia in orthopaedic and hand surgery. RESULTS : The review summarises the existing research pertaining to WALANT. It discusses the anaesthetic solution constituents, administration technique and applications of WALANT, highlighting the safety profile and benefits to patients and healthcare systems alike. CONCLUSION : The WALANT technique is safe, economical, and acceptable to patients. It should form part of the orthopaedic surgeon’s armamentarium. Future research should investigate the benefits of intraoperative functional assessment of the awake patient.http://journal.saoa.org.zadm2022Orthopaedic Surger

Effects of rat anti-VEGF antibody in a rat model of corneal graft rejection by topical and subconjunctival routes

PURPOSE: To compare the effect of a rat anti-VEGF antibody, administered either by topical or subconjunctival (SC) routes, on a rat model of corneal transplant rejection.METHODS: Twenty-four rats underwent corneal transplantation and were randomized into four treatment groups (n=6 in each group). G1 and G2 received six SC injections (0.02 ml 10 µg/ml) of denatured (G1) or active (G2) anti-VEGF from Day 0 to Day 21 every third day. G3 and G4 were instilled three times a day with denatured (G3) or active (G4) anti-VEGF drops (10 µg/ml) from Day 0 to Day 21. Corneal mean clinical scores (MCSs) of edema (E), transparency (T), and neovessels (nv) were recorded at Days 3, 9, 15, and 21. Quantification of neovessels was performed after lectin staining of vessels on flat mounted corneas.RESULTS: Twenty-one days after surgery, MCSs differed significantly between G1 and G2, but not between G3 and G4, and the rejection rate was significantly reduced in rats receiving active antibodies regardless of the route of administration (G2=50%, G4=66.65% versus G1 and G3=100%; p<0.05). The mean surfaces of neovessels were significantly reduced in groups treated with active anti-VEGF (G2, G4). However, anti-VEGF therapy did not completely suppress corneal neovessels.CONCLUSIONS: Specific rat anti-VEGF antibodies significantly reduced neovascularization and subsequent corneal graft rejection. The SC administration of the anti-VEGF antibody was more effective than topical instillation

Computed tomography assessment of postoperative gastric vascular supply and staple-line leak development after sleeve gastrectomy

Background: Residual arterial supply of the gastric tube after sleeve gastrectomy (SG) can be damaged by surgery, which can reduce gastric tube perfusion and could promote postoperative leakage. Objective: To compare the postoperative vascularization of the gastric tube using early computed tomography (CT) scanning after SG in patients with or without postoperative staple-line leak. Setting: University hospital. Methods: A retrospective analysis of a prospective database was performed in consecutive patients undergoing SG. Patients who presented with a staple-line leak were matched (1:3) with a control group of patients who underwent surgery without postoperative morbidity during the same period. Gastric tube vascularization was studied on a postoperative day 2 CT scan in both groups of patients. Results: During the study period, 1826 patients underwent SG, including 42 patients (2.3%) who presented with a staple-line leak. Those 42 patients were successfully matched to 126 control patients. Global identification of residual gastric arterial supply in early postoperative CT scans was similar in patients with or without staple-line leak after SG. However, residual vascular supply of the gastroesophageal junction (i.e., terminal and anterior cardiotuberosity branches of the left gastric artery or left inferior phrenic artery) was more frequently interrupted by the staple line in the group of patients who developed a gastric leak. Conclusion: This study suggests a correlation between interruption of the main arteries supplying the gastroesophageal junction by the staple line on early postoperative CT scans and the development of gastric leak after SG. These results support the vascular theory as one of the causes of leak after SG

Silver fillers aspect ratio influence on electrical and thermal conductivity in PEEK/Ag nanocomposites

The development of polymer based conductive composites is required in aeronautical applications where electrostatic charges and heat need to be evacuated. Optimization of conductive filler content is necessary to maintain low density and high mechanical properties provided by the polymer matrix. We introduced silver nanoparticles in Polyetheretherketone. Electrical conductivity, specific heat capacity, thermal conductivity and thermal diffusivity have been determined as a function of filler content and temperature. In particular, we studied the influence of silver nanoparticles aspect ratio on these thermal properties. We compared nanospheres with nanowires. A low electrical percolation threshold (0.55 vol%) is obtained for silver nanowires composites compared to spherical particles (10.8 vol%). Thermal conductivity increases with silver content and the influence of filler aspect ratio is interesting: thanks to nanowires, the thermal conductivity enhancement is reached for lower silver content. Experimental data are well fitted with Nan model. Specific heat capacity decreases with the introduction of silver nanoparticles, following the mixture rule independently of aspect ratio. Composites thermal diffusivity also increases with increasing silver content and influence of filler aspect ratio can be brought to light. Temperature dependence of these thermal properties indicate a dominant heat transport mechanism typical of disordered materials

Laminar–turbulent intermittency in pipe flow for an Herschel–Bulkley fluid: Radial receptivity to finite-amplitude perturbations

We investigate the laminar-to-turbulent transition for non-Newtonian Herschel–Bulkley fluids that exhibit either a shear-thinning or shear-thickening behavior. The reduced-order model developed in this study also includes the effect of yield-stress for the fluid. Within our model framework, we investigate how the Newtonian dynamics change when significant non-Newtonian effects are considered either via the flow index n or the yield-stress τ0 or both. We find that an increase in τ0 as well as a decrease in n lead to a delayed transition if a perturbation of the given turbulent intensity is injected at various radial locations. As the radial position of the injection for the perturbation is varied in this study, our reduced-order model allows for the investigation of the flow receptivity to the finite-amplitude perturbations and to their radial position of inception. We observe that, for a given mean flow profile, the same perturbation becomes more prone to induce turbulence the closer it approaches the wall because of its initial amplitude being relatively higher with respect to the local mean flow. An opposite trend is found when the perturbation amplitude is rescaled on the local mean flow

The DESI One-Percent Survey: Exploring the Halo Occupation Distribution of Luminous Red Galaxies and Quasi-Stellar Objects with AbacusSummit

We present the first comprehensive Halo Occupation Distribution (HOD) analysis of the DESI One-Percent survey Luminous Red Galaxy (LRG) and Quasi-Stellar Object (QSO) samples. We constrain the HOD of each sample and test possible HOD extensions by fitting the redshift-space galaxy 2-point correlation functions in 0.15 < r < 32 Mpc/h in a set of fiducial redshift bins. We use AbacusSummit cubic boxes at Planck 2018 cosmology as model templates and forward model galaxy clustering with the AbacusHOD package. We achieve good fits with a standard HOD model with velocity bias, and we find no evidence for galaxy assembly bias or satellite profile modulation at the current level of statistical uncertainty. For LRGs in 0.4 < z < 0.6, we infer a satellite fraction of fsat = 11+-1%, a mean halo mass of log10 Mh = 13.40+0.02-0.02, and a linear bias of blin = 1.93+0.06-0.04. For LRGs in 0.6 < z < 0.8, we find fsat = 14+-1%, log10 Mh = 13.24+0.02-0.02, and blin = 2.08+0.03-0.03. For QSOs, we infer fsat = 3+8-2%, log10 Mh = 12.65+0.09-0.04, and blin = 2.63+0.37-0.26 in redshift range 0.8 < z < 2.1. Using these fits, we generate a large suite of high-fidelity galaxy mocks. We also study the redshift-evolution of the DESI LRG sample from z = 0.4 up to z = 1.1, revealing significant and interesting trends in mean halo mass, linear bias, and satellite fraction.Comment: Submitted to MNRAS, comments welcom

Vers une meilleure interprétation de la connexion galaxies-halos pour les galaxies à raies d'émission du relevé spectroscopique DESI

Le Dark Energy Spectroscopic Instrument (DESI) vise à sonder la structuration à grande échelle de l'Univers en mesurant le décalage vers le rouge de ~40 millions de galaxies dont 17M de galaxies à raies d'émission (ELGs). Aux petites échelles, les mesures de distribution spatiale des galaxies sont essentielles pour étudier la connexion galaxie-halo, i.e. la façon dont les galaxies peuplent les halos de matière noire. Cette thèse est consacrée à l'analyse de la connexion galaxie-halo des ELGs de DESI et vise, d'une part, à donner une image complète de la façon dont les ELGs sont connectées au champ de matière noire, et d'autre part, à générer des catalogues simulés de galaxies de haute fidélité pour tester les analyses cosmologiques et corriger les effets systématiques observationnels et théoriques. Pour contraindre la connexion galaxie-halo des ELGs, nous utilisons les données des deux premiers mois de DESI, soit ~270k ELGs à 0.8 < z < 1.6. La grande complétude de cet échantillon permet de mesurer la distribution spatiale des galaxies jusqu'à de très petites échelles, jamais sondées auparavant. La caractéristique la plus frappante est un fort signal aux très petites échelles. Nous analysons ces données dans le cadre de la distribution d'occupation des halos (HOD), une approche empirique reliant les galaxies et les halos de matière noire dans les simulations à N-corps. Pour ce faire, nous avons développé et testé une méthode pour ajuster les modèles HOD basée sur des processus gaussiens, puis l'avons appliquée aux données. Nous considérons différentes distributions pour les galaxies centrales et des hypothèses standard pour les satellites en termes d'assignation, positionnement et dispersion de vitesse. Pour tous les modèles considérés, nous trouvons une masse moyenne de halo pour les ELGs de l'ordre de 10¹¹⋅⁹ Msol et une dispersion des vitesses des satellites environ 50% plus grande que celle des particules de matière noire. Nous étudions diverses extensions de nos modèles de base, tels que le biais d'assemblage, la conformité centrale-satellite, un profil de positionnement des satellites modifié et varions la cosmologie de référence. La conformité permet de retrouver une compréhension plus physique de la HOD. Les autres extensions n'apportent pas de changement significatif à nos résultats, excepté quand nous permettons aux ELGs satellites de se situer en dehors du rayon viriel des halos. C'est avec cette hypothèse que nous obtenons la meilleure modélisation des mesures de distribution spatiale, correspondant à ~0.5% d'ELGs résidant à la périphérie des halos de matière noire.The Dark Energy Spectroscopic Instrument DESI aims to probe the large scale structure of the Universe by measuring ~40 million of galaxy/quasar redshifts including 17M redshifts of emission line galaxies (ELGs). At small scales, clustering measurements are invaluable to study the so-called galaxy-halo connection, i.e. the way galaxies populate dark matter halos. This thesis is dedicated to the analysis of the galaxy-halo connection of DESI ELGs and aims, on one hand, to give a complete picture of how ELGs are connected to the dark matter field, and, on the other hand, to generate high-fidelity simulated galaxy catalogues to test cosmological analysis pipelines and mitigate observational and theoretical systematic effects. To constrain the ELG galaxy-halo connection we focus on the first 2 months of DESI, which collected ~270k ELGs at 0.8 < z < 1.6. The high completeness of this sample made it possible to measure galaxy clustering down to very small scales, never probed before. The most striking feature of the measurements is a strong signal at the smallest scales. We analyse these data using the halo occupation distribution (HOD) framework, an empirical approach to link galaxies and dark matter halos in N-body simulations. To this end, we develop and test a method based on Gaussian processes to fit HOD models, which we then apply to data. We consider different distributions for the central galaxies and standard assumptions for satellite assignment, positioning and velocities, which we then vary.For all models considered, we report a mean halo mass of the ELG sample around 10¹¹⋅⁹ Msol and satellite velocity dispersions about 50% higher than that of dark matter particles. We study various extensions of our baseline HOD models such as assembly bias, central-satellite conformity, modified satellite positioning and vary the fiducial cosmology. Conformity allows us to recover a more physical understanding of the HOD. The other extensions bring no significant change to our results, except when we allow satellite ELGs to lie outside of the halo virial radius. It is with this assumption that we obtain the best modelling of the measured clustering, corresponding to ~0.5% of ELGs residing in the halo outskirts

Vers une meilleure interprétation de la connexion galaxies-halos pour les galaxies à raies d'émission du relevé spectroscopique DESI

The Dark Energy Spectroscopic Instrument DESI aims to probe the large scale structure of the Universe by measuring ~40 million of galaxy/quasar redshifts including 17M redshifts of emission line galaxies (ELGs). At small scales, clustering measurements are invaluable to study the so-called galaxy-halo connection, i.e. the way galaxies populate dark matter halos. This thesis is dedicated to the analysis of the galaxy-halo connection of DESI ELGs and aims, on one hand, to give a complete picture of how ELGs are connected to the dark matter field, and, on the other hand, to generate high-fidelity simulated galaxy catalogues to test cosmological analysis pipelines and mitigate observational and theoretical systematic effects. To constrain the ELG galaxy-halo connection we focus on the first 2 months of DESI, which collected ~270k ELGs at 0.8 < z < 1.6. The high completeness of this sample made it possible to measure galaxy clustering down to very small scales, never probed before. The most striking feature of the measurements is a strong signal at the smallest scales. We analyse these data using the halo occupation distribution (HOD) framework, an empirical approach to link galaxies and dark matter halos in N-body simulations. To this end, we develop and test a method based on Gaussian processes to fit HOD models, which we then apply to data. We consider different distributions for the central galaxies and standard assumptions for satellite assignment, positioning and velocities, which we then vary.For all models considered, we report a mean halo mass of the ELG sample around 10¹¹⋅⁹ Msol and satellite velocity dispersions about 50% higher than that of dark matter particles. We study various extensions of our baseline HOD models such as assembly bias, central-satellite conformity, modified satellite positioning and vary the fiducial cosmology. Conformity allows us to recover a more physical understanding of the HOD. The other extensions bring no significant change to our results, except when we allow satellite ELGs to lie outside of the halo virial radius. It is with this assumption that we obtain the best modelling of the measured clustering, corresponding to ~0.5% of ELGs residing in the halo outskirts.Le Dark Energy Spectroscopic Instrument (DESI) vise à sonder la structuration à grande échelle de l'Univers en mesurant le décalage vers le rouge de ~40 millions de galaxies dont 17M de galaxies à raies d'émission (ELGs). Aux petites échelles, les mesures de distribution spatiale des galaxies sont essentielles pour étudier la connexion galaxie-halo, i.e. la façon dont les galaxies peuplent les halos de matière noire. Cette thèse est consacrée à l'analyse de la connexion galaxie-halo des ELGs de DESI et vise, d'une part, à donner une image complète de la façon dont les ELGs sont connectées au champ de matière noire, et d'autre part, à générer des catalogues simulés de galaxies de haute fidélité pour tester les analyses cosmologiques et corriger les effets systématiques observationnels et théoriques. Pour contraindre la connexion galaxie-halo des ELGs, nous utilisons les données des deux premiers mois de DESI, soit ~270k ELGs à 0.8 < z < 1.6. La grande complétude de cet échantillon permet de mesurer la distribution spatiale des galaxies jusqu'à de très petites échelles, jamais sondées auparavant. La caractéristique la plus frappante est un fort signal aux très petites échelles. Nous analysons ces données dans le cadre de la distribution d'occupation des halos (HOD), une approche empirique reliant les galaxies et les halos de matière noire dans les simulations à N-corps. Pour ce faire, nous avons développé et testé une méthode pour ajuster les modèles HOD basée sur des processus gaussiens, puis l'avons appliquée aux données. Nous considérons différentes distributions pour les galaxies centrales et des hypothèses standard pour les satellites en termes d'assignation, positionnement et dispersion de vitesse. Pour tous les modèles considérés, nous trouvons une masse moyenne de halo pour les ELGs de l'ordre de 10¹¹⋅⁹ Msol et une dispersion des vitesses des satellites environ 50% plus grande que celle des particules de matière noire. Nous étudions diverses extensions de nos modèles de base, tels que le biais d'assemblage, la conformité centrale-satellite, un profil de positionnement des satellites modifié et varions la cosmologie de référence. La conformité permet de retrouver une compréhension plus physique de la HOD. Les autres extensions n'apportent pas de changement significatif à nos résultats, excepté quand nous permettons aux ELGs satellites de se situer en dehors du rayon viriel des halos. C'est avec cette hypothèse que nous obtenons la meilleure modélisation des mesures de distribution spatiale, correspondant à ~0.5% d'ELGs résidant à la périphérie des halos de matière noire

Vers une meilleure interprétation de la connexion galaxies-halos pour les galaxies à raies d'émission du relevé spectroscopique DESI

The Dark Energy Spectroscopic Instrument DESI aims to probe the large scale structure of the Universe by measuring ~40 million of galaxy/quasar redshifts including 17M redshifts of emission line galaxies (ELGs). At small scales, clustering measurements are invaluable to study the so-called galaxy-halo connection, i.e. the way galaxies populate dark matter halos. This thesis is dedicated to the analysis of the galaxy-halo connection of DESI ELGs and aims, on one hand, to give a complete picture of how ELGs are connected to the dark matter field, and, on the other hand, to generate high-fidelity simulated galaxy catalogues to test cosmological analysis pipelines and mitigate observational and theoretical systematic effects. To constrain the ELG galaxy-halo connection we focus on the first 2 months of DESI, which collected ~270k ELGs at 0.8 < z < 1.6. The high completeness of this sample made it possible to measure galaxy clustering down to very small scales, never probed before. The most striking feature of the measurements is a strong signal at the smallest scales. We analyse these data using the halo occupation distribution (HOD) framework, an empirical approach to link galaxies and dark matter halos in N-body simulations. To this end, we develop and test a method based on Gaussian processes to fit HOD models, which we then apply to data. We consider different distributions for the central galaxies and standard assumptions for satellite assignment, positioning and velocities, which we then vary.For all models considered, we report a mean halo mass of the ELG sample around 10¹¹⋅⁹ Msol and satellite velocity dispersions about 50% higher than that of dark matter particles. We study various extensions of our baseline HOD models such as assembly bias, central-satellite conformity, modified satellite positioning and vary the fiducial cosmology. Conformity allows us to recover a more physical understanding of the HOD. The other extensions bring no significant change to our results, except when we allow satellite ELGs to lie outside of the halo virial radius. It is with this assumption that we obtain the best modelling of the measured clustering, corresponding to ~0.5% of ELGs residing in the halo outskirts.Le Dark Energy Spectroscopic Instrument (DESI) vise à sonder la structuration à grande échelle de l'Univers en mesurant le décalage vers le rouge de ~40 millions de galaxies dont 17M de galaxies à raies d'émission (ELGs). Aux petites échelles, les mesures de distribution spatiale des galaxies sont essentielles pour étudier la connexion galaxie-halo, i.e. la façon dont les galaxies peuplent les halos de matière noire. Cette thèse est consacrée à l'analyse de la connexion galaxie-halo des ELGs de DESI et vise, d'une part, à donner une image complète de la façon dont les ELGs sont connectées au champ de matière noire, et d'autre part, à générer des catalogues simulés de galaxies de haute fidélité pour tester les analyses cosmologiques et corriger les effets systématiques observationnels et théoriques. Pour contraindre la connexion galaxie-halo des ELGs, nous utilisons les données des deux premiers mois de DESI, soit ~270k ELGs à 0.8 < z < 1.6. La grande complétude de cet échantillon permet de mesurer la distribution spatiale des galaxies jusqu'à de très petites échelles, jamais sondées auparavant. La caractéristique la plus frappante est un fort signal aux très petites échelles. Nous analysons ces données dans le cadre de la distribution d'occupation des halos (HOD), une approche empirique reliant les galaxies et les halos de matière noire dans les simulations à N-corps. Pour ce faire, nous avons développé et testé une méthode pour ajuster les modèles HOD basée sur des processus gaussiens, puis l'avons appliquée aux données. Nous considérons différentes distributions pour les galaxies centrales et des hypothèses standard pour les satellites en termes d'assignation, positionnement et dispersion de vitesse. Pour tous les modèles considérés, nous trouvons une masse moyenne de halo pour les ELGs de l'ordre de 10¹¹⋅⁹ Msol et une dispersion des vitesses des satellites environ 50% plus grande que celle des particules de matière noire. Nous étudions diverses extensions de nos modèles de base, tels que le biais d'assemblage, la conformité centrale-satellite, un profil de positionnement des satellites modifié et varions la cosmologie de référence. La conformité permet de retrouver une compréhension plus physique de la HOD. Les autres extensions n'apportent pas de changement significatif à nos résultats, excepté quand nous permettons aux ELGs satellites de se situer en dehors du rayon viriel des halos. C'est avec cette hypothèse que nous obtenons la meilleure modélisation des mesures de distribution spatiale, correspondant à ~0.5% d'ELGs résidant à la périphérie des halos de matière noire