Derniers dépôts sur Hal UA

• [hal-02531005] Comparison of five dose calculation algorithms in a heterogeneous media using design of experiment

  3 avr. 2020 14:39

  Purpose Design of experiments (DoE) provides a methodology to reveal the influence of input values on the measured output with a limited number of trials. The purpose of this study was to describe how DoE can be used to evaluate the performances of several dose calculation systems in heterogeneous media, including algorithms like Pencil Beam (PB), Anisotropic Analytical Algorithm (AAA), Acuros XB (AXB), Monte Carlo (MC) and Collapsed Cone Volume (CCV). Method This study was carried out using a CIRS Model 002LFC IMRT Thorax Phantom customized with a water-equivalent heterogeneity inside the lung. The calculated dose distributions were compared to Gafchromic® EBT3 film measurements. The beam configurations were selected using DoE to study the influence of five parameters simultaneously (energy, collimator angulation, gantry angulation, X and Y jaws) and to optimize the number of experiments. An analysis of variance was performed over the entire irradiation field and over various regions of interest (tumour, shadow of tumour and lungs). Results DoE enabled to quantify and determine the statistically significant factors, leading to an evaluation of the dose calculation systems in the lung case. The resulting scoring could be as follow (from best to worst): AXB_Dm, CCV, AXB_Dw, XVMC_Dm, XVMC_Dw, AAA and last PB. Differences between the algorithms were specially observed in the tumour and the shadow regions. Conclusion DoE is a robust statistical method to compare several dose calculation systems. The various analyses lead to the conclusion that AXB handled more accurately most of the situations investigated in heterogeneous media.

• [hal-03963204] Crystal structures, frustrated magnetism, and chemical pressure in Sr-doped Ba$_3$ Ni Sb$_2$ O$_9$ perovskites

  30 janv. 2023 16:27

  The effects of chemical pressure on the structural and magnetic properties of the triple perovskite Ba3NiSb2O9 are investigated by substituting Sr2+ ions for Ba2+ ions. Two Ba(3-x)SrxNiSb(2)O(9) phases could be stabilized via a solid-state reaction at ambient pressure (AP) in air. The 6H with Sb2O9 pairs (x = 0) -> 6H with NiSbO9 pairs (x = 0.5) -> 3C (cubic with corner-sharing octahedral, x = 1.25) sequence of structural phases occurs with increasing Sr content, i.e., chemical pressure, which is like that previously reported for pure samples of Ba3NiSb2O9 obtained under increasing high physical pressure (HP). For the 6H Ba2.5Sr0.5NiSb2O9 (x = 0.5) phase, using combined Rietveld refinements of powder x-ray and neutron diffraction patterns, precession electron diffraction tomography data collected on thin crystals, aberration-corrected high-angle annular dark field scanning transmission electron microscopy coupled to energy dispersive x-ray spectroscopy mapping, we reach the conclusion that the structure features corner-sharing SbO6 octahedra and NiSbO9 pairs of face-shared octahedra (or Ni-Sb dumbbells) with either a random orientation of the Ni-Sb dumbbells or nanosized chemical correlations for the dumbbell arrangement. As observed in HP Ba3NiSb2O9 produced through synthesis at 9 GPa, AP Ba1.75Sr1.25NiSb2O9 (x = 1.25) crystallizes in a 3C double perovskite A2BB'O6 cubic structure where A, B, and B' sites are occupied by (Ba + Sr), Sb, and (2/3Ni + 1/3Sb) atoms, respectively. The B' sites, which are randomly occupied by spin-1 Ni2+ and diamagnetic Sb5+, form a face-centered-cubic (FCC) sublattice where the Ni2+ amount stays above the site percolation threshold. Weiss temperatures (eta -65 and ti -213 K for Ba2.5Sr0.5NiSb2O9 and Ba1.75Sr1.25NiSb2O9, respectively) indicate that dominant magnetic interactions between Ni2+ spins are antiferromagnetic with magnitudes like those observed in the corresponding HP phases of pure Ba3NiSb2O9. As for the 6H HP Ba3NiSb2O9 compound, in 6H Ba2.5Sr0.5NiSb2O9, muon spin relaxation (mu SR) measurements identify a dynamic magnetic state down to the base temperature (95 mK), consistent with a previously published inelastic neutron scattering study. For 3C Ba1.75Sr1.25NiSb2O9, mu SR and 121Sb nuclear magnetic resonance measurements both indicate the presence of a transition to a static magnetic state below 11(1) K with a significant amount of disorder in this frozen state, in contrast to the spin-liquid state previously suggested for the 3C HP phase of Ba3NiSb2O9. Consistently, a broad maximum is observed in the specific heat at the same temperature. Building on the structural data, the magnetic properties of HP 6H Ba3NiSb2O9 and AP 6H Ba2.5Sr0.5NiSb2O9 are discussed in light of recent works on triangular and J(1) -J(2) honeycomb systems with or without quenched disorder. We are led to the conclusion that the driving force toward a spin-liquid-like state is quenched disorder which needs to be incorporated in J(1) -J(2) honeycomb models. Our evidence of a magnetic transition to a frozen magnetic ground state for the AP Sr-doped 3C phase is in line with models for geometrically frustrated FCC antiferromagnets. This calls for a better experimental and possibly theoretical understanding of the HP 3C phase.

• [hal-02483171] Severe poisoning with naproxen causing coagulopathy

  18 févr. 2020 15:31

  [...]

• [halshs-03939552] Être adolescent au temps de la guerre d’indépendance algérienne, d’Alger au Béarn

  15 janv. 2023 10:07

  Larges extraits d’un entretien réalisé par Yves Denéchère, professeur d’histoire contemporaine à l’université d’Angers – UMR TEMOS, dans le cadre du programme EnJeu[x] Enfance et jeunesse. Cet entretien a eu lieu au domicile de M. Ferdjioui à Pau, en partie en compagnie de son épouse, le 6 juin 2016, durée 1 h 48. Entretien enregistré, retranscrit et reproduit avec l’autorisation de M. Ferdjioui accordée le 15 avril 2020.

• [halshs-03408961] L’ADOPTION TRANSNATIONALE ENTRE IDÉOLOGIES, HUMANITAIRE ET CATHARSIS. Fins de guerres, décolonisation et guerre froide en France et aux États-Unis (1945-1975)

  29 oct. 2021 15:54

  [...]

• [halshs-03749445] Louise Weiss. Un apostolat pour la Société des Nations

  10 août 2022 20:32

  [...]

• [halshs-03939563] Pour une étude historique des pratiques illicites dans l’adoption internationale

  15 janv. 2023 10:47

  [...]

• [hal-03842420] Ternary Planar Heterojunction Organic Solar Cells Based on the Ternary Active Layers: alpha-6T/AlPcCl/C60

  7 nov. 2022 16:25

  Ternary planar heterojunction organic solar cells (PHJ-OPVs) were fabricated using three or- ganic small molecules, alpha-sexithiophene (α-6T), aluminum phthalocyanine chloride (AlPcCl) and fullerene (C60). These molecules can be easily sublimated under a vacuum; they have complementary optical absorption spectra and their energy band structure alignment is favorable for electronic charge transfers. Moreover, α-6T and AlPcCl have almost the same HOMO, which is desirable to avoid any decrease in open circuit voltage. The AlPcCl intercalated layer bridges the energy levels of the electron donor, α-6T, and the electron acceptor, C60, which facilitates charge transport through the energy cascade effect. Moreover, the charge carrier mobility measurements of AlPcCl, using the space charge limited current method, demonstrated that it iss ambipolar. All these properties combine to improve the power conversion efficiency (PCE) of PHJ-OPVs by moving from binary structures (α-6T/C60, α-6T/AlPcCl and AlPcCl/C60) to ternary ones (α-6T/AlPcCl/C60). We show, in this study, that both interfaces of the ternary PHJ-OPVs are efficient for carrier separation. After optimization of the different layer thickness, we show that, by comparing the optimum efficiencies of the binary PHJ-OPVs, the realization of ternary PHJ-OPVs, based on the active layers α-6T/AlPcCl/C60, using the following optimized method, allows us to achieve a PCE of 4.33%.

• [halshs-03965883] « L’émergence de la promotion de l’égalité femmes-hommes dans le droit des collectivités territoriales »

  31 janv. 2023 16:46

  [...]

• [hal-03443207] Humoral response to a third injection of BNT162b2 vaccine in patients on maintenance haemodialysis

  23 nov. 2021 15:13

  Abstract Background Humoral response against sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after two doses of BNT162b2 (Pfizer-BioNTech) has been proven to be less intense in maintenance dialysis patients as compared with healthy subjects, leading the French authorities to recommend a third injection in this population. Here we investigated the response to the third injection in two cohorts of haemodialysis (HD) patients. Methods Data from two prospective observational cohorts were collected. In the first (‘systematic’) cohort, patients from two HD centres (n = 66) received a third injection of BNT162b2, regardless of the response after two injections. In the second (‘conditional’) cohort, the injection was only prescribed to patients (n = 34) with no or low response to the previous two doses. In both cohorts, the third dose was injected 1–2 months after the second dose. Serology was performed after the second and third doses to assess anti-Spike immunoglobulin G (S IgG) antibody titre. Results In the systematic cohort, anti-S IgG was found in 83.3 and 92.4% of patients after the second and third doses of BNT162b2, respectively. In this cohort, 6/11 (54.5%) and 20/21 (95.2%) patients switched from non-responder to low responder and from low responder to high responder, respectively. In low and high responders to two doses, 50/55 (90.9%) at least doubled their anti-S IgG titre. Similar trends were observed in the conditional cohort. Conclusions In maintenance HD patients, humoral response against SARS-CoV-2 was boosted after a third dose of BNT162b2, allowing seroconversion in more than half of non-responders. These data may support an intensified vaccination protocol with a third dose of BNT162b2 in dialysis patients.