11 research outputs found
THE WAVELENGTH-RATIO METHOD : A NOVEL APPROACH TO EXTINCTION-FREE DETERMINATION OF FM/FN
Les variations, en fonction de la longueur d'onde, des réflectivités ρ+ et ρ- correspondant aux deux polarisations des neutrons incidents devraient, pour un monocristal magnétique en forme de plaque, être liées par une loi d'échelle indépendante de l'extinction. Cette propriété permettrait, moyennant vérification expérimentale, d'obtenir très directement le rapport des composantes magnétiques et nucléaires des facteurs de structure, sans avoir à effectuer des corrections d'extinction.The variations with wavelength of the reflectivities ρ+ and ρ- corresponding to the two polarization states of the incident neutrons should be related through an extinction - independent scaling law in the case of a plate-shaped crystal. If borne out by experiment, this property should provide a very direct way of measuring the ratio of the magnetic and nuclear contributions to the structure factor, without use of extinction corrections
OBSERVATION OF PENDELLÖSUNG EFFECT IN POLARIZED NEUTRON SCATTERING FROM A MAGNETIC CRYSTAL
Nous avons obtenu ce que nous croyons être la première mise en évidence expérimentale de l'effet de Pendellösung en diffraction des neutrons par un cristal magnétique. L'échantillon, un monocristal de YIG, a été sélectionné et taillé de façon que les défauts qu'il présente - des bandes de croissance, pour l'essentiel - n'aient pas d'influence sur la diffraction dans la géométrie que nous avons choisie. Nous avons mesuré le rapport de retournement R ainsi que les pouvoirs réflecteurs ρ+ et ρ- correspondant au deux polarisations du faisceau de neutrons, en fonction de la longueur d'onde. R(λ) et ρ+(λ) présentent bien les oscillations prévues dans le cas d'un cristal parfait, mais avec une amplitude plus faible dont on peut rendre compte, par exemple, en utilisant la théorie statistique de la diffraction développée par Kato.We have obtained what we believe to be the first experimental evidence, in neutron diffraction from a magnetic crystal, of the Pendellösung effect predicted by dynamical theory. We measured the flipping ratio, R, and the reflecting powers for both polarizations, ρ+ and ρ- as a function of wavelength, from a carefully selected YIG single crystal, cut in a such a way that its main defects - growth bands are inoperative in the chosen scattering geometry. Both R(λ) and ρ+(λ) present characteristic oscillating behaviours, related to those calculated for a perfect crystal. It is possible to account for the discrepancy between the experimental and calculated amplitudes of the oscillations using e.g. Kato's statistical theory of diffraction
Quantitative aspects of coherent hart X-ray imaging: Talbot images and holographic reconstruction
Observation of magnetization distribution in a correlated spin glass system : amorphous Tb-Co magnetic films
The magnetization distribution in sputtered random-anisotropy TbCo 3 amorphous films was observed by transmission electron microscopy at room, low and high temperature. In the as-grown films, about 8 x 10 -8 m thick, a disordered structure on a scale of 10-7 m, consistent with the Imry and Ma picture for a correlated spin glass, is observed at room temperature. This structure is unaffected by cooling but is irreversibly and progressively simplified on heating. Domain wall contrast is reversed, with no change in wall positions, when going through the compensation temperature of about 270 K. In thinned fragments, the domain structure is qualitatively different, due to terbium loss near the surfaces.La distribution spatiale de l'aimantation a été observée par microscopie électronique en transmission sur des couches amorphes de TbCo3 à anisotropie aléatoire obtenues par pulvérisation cathodique, à température ambiante ainsi qu'à hautes et basses températures. Les couches brutes de préparation, d'épaisseur 8 x 10-8 m environ, montrent à l'ambiante une structure magnétique désordonnée dont l'échelle caractéristique, 10 -7 m, est compatible avec le modèle de Imry et Ma pour un verre de spins corrélés. Cette structure n'est pas affectée par le refroidissement, mais elle se simplifie de façon irréversible et progressive lors du chauffage. Le contraste des parois de domaines est inversé, sans modification des positions des parois, à la traversée de la température de compensation, voisine de 270 K. Dans des fragments amincis, la structure en domaines est qualitativement différente par suite de la perte de terbium dans les régions superficielles
Holotomography: quantitative phase tomography with micrometer resolution using hard synchrotron radiation X-rays
Observation of pendellösung effect in polarized neutron scattering from a magnetic crystal
Local measurement of magnetization in a gallium-substituted YIG crystal by neutron spin echo
Afatinib as second-line treatment in patients with recurrent/metastatic squamous cell carcinoma of the head and neck : subgroup analyses of treatment adherence, safety and mode of afatinib administration in the LUX-Head and Neck 1 trial
Objectives: Patients with head and neck squamous cell carcinoma (HNSCC) can experience severe symptom burden and/or difficulty swallowing, leading to problems with treatment adherence/administration. In LUX-Head and Neck 1 (LH&N1; NCT01345682), second-line afatinib improved progression-free survival (PFS) versus methotrexate in patients with recurrent/metastatic HNSCC. We report adherence and safety across pre-specified and additional subgroups potentially linked to afatinib PFS benefit in LH&N1 (p16 status, smoking history), and afatinib adherence, safety and efficacy by administration (oral versus feeding tube; post-hoc analysis). Methods: Patients were randomized (2:1) to afatinib (40 mg/day) or intravenous methotrexate (40 mg/m2/week). Results: Among 320 afatinib-treated and 160 methotrexate-treated patients, 83\u201392% and 76\u201392% (of patients with data available) across all subgroups took 6580% of treatment. Across p16 status and smoking history subgroups, the most common treatment-related adverse events (AEs) were diarrhea (70\u201391%), rash/acne (72\u201384%), stomatitis (34\u201373%) with afatinib; and included stomatitis (39\u2013100%), fatigue (22\u201350%), nausea (19\u201336%) with methotrexate. Dose reduction decreased AE incidence/severity. Baseline characteristics were generally similar between oral/feeding tube (n = 276/n = 46) groups. 89%/89% (of patients with data available) took 6580% of assigned afatinib. Median PFS was 2.6 versus 2.7 months (hazard ratio: 0.997; 95% confidence interval: 0.72\u20131.38). The most common afatinib-related AEs were: rash/acne (74% versus 74%), diarrhea (73% versus 65%), stomatitis (40% versus 30%). Conclusion: Subgroup analyses of LH&N1 demonstrate that afatinib has predictable and manageable safety across patient subgroups, with high treatment adherence, and is effective via oral and feeding tube administration