Holographic Experiments on Defects

Using the AdS/CFT correspondence, we study the anisotropic charge transport properties of both supersymmetric and non-supersymmetric matter fields on (2+1)-dimensional defects coupled to a (3+1)-dimensional N=4 SYM "heat bath". We focus on the cases of a finite external background magnetic field, finite net charge density and finite mass and their combinations. In this context, we also discuss the limitations due to operator mixing that appears in a few situations and that we ignore in our analysis. At high frequencies, we discover a spectrum of quasi-particle resonances due to the magnetic field and finite density and at small frequencies, we perform a Drude-like expansion around the DC limit. Both of these regimes display many generic features and some features that we attribute to strong coupling, such as a minimum DC conductivity and an unusual behavior of the "cyclotron" and plasmon frequencies, which become related to the resonances found in the conformal case in an earlier paper. We further study the hydrodynamic regime and the relaxation properties, from which the system displays a set of different possible transitions to the collisionless regime. The mass dependence can be cast in two regimes: a generic relativistic behavior dominated by the UV and a non-linear hydrodynamic behavior dominated by the IR. In the massless case, we furthermore extend earlier results from the literature to find an interesting self-duality under a transformation of the conductivity and the exchange of density and magnetic field.Comment: 76 pages, 45 figures (jpg and pdf), IJMPA style; section on operator mixing and references added, typos fixed, final version published in IJMP

Scanner abdominal : étude comparative de l’exposition patient en routine clinique sur des appareils avec et sans reconstruction itérative

Objectif : comparer la dose délivrée aux patients et la qualité d’image en routine clinique lors de la réalisation d’un scanner abdominal ne disposant pas des techniques de reconstructions itératives (RI) par rapport à un examen réalisé sur un scanner disposant des RI. Matériels et méthodes : il s’agit d’une étude rétrospective incluant 30 patients ayant eu deux examens abdominaux sur un scanner 40 coupes (TDM40) et sur un scanner 256 coupes avec RI (TDM256). Les patients, suivis pour une pathologie abdominale chronique, ont eu un examen de même indication sur chaque scanner avec un protocole comprenant une phase abdomino-pelvienne au temps portal. La longueur d’acquisition, la dose efficace et le Produit Dose Longueur (PDL) ainsi que des évaluations quantitatives et qualitatives de l’image ont été comparés. Résultats : la dose efficace moyenne pour un examen était de 17,3 mSv avec le TDM40 (PDL : 1019 mGy.cm) contre 11,1 mSv avec le TDM256 (PDL : 654 mGy.cm) soit une réduction de 35,8 % (p < 0,001). Les longueurs d’acquisitions et l’évaluation quantitative étaient comparables dans les deux groupes. L’évaluation qualitative était légèrement supérieure sur le TDM40 mais aucun examen n’a été considéré comme sous-optimal. Conclusion : l’utilisation d’un scanner équipé de RI permet une réduction significative de la dose efficace tout en préservant une bonne qualité d’image

Twenty-five novel mutations including duplications in the ATP7A gene.

Menkes disease (MD) and occipital horn syndrome (OHS) are allelic X-linked recessive copper deficiency disorders resulting from ATP7A gene mutations. MD is a severe condition leading to progressive neurological degeneration and death in early childhood, whereas OHS has a milder phenotype with mainly connective tissue abnormalities. Until now, molecular analyses have revealed only deletions and point mutations in both diseases. This study reports new molecular data in a series of 40 patients referred for either MD or OHS. We describe 23 point mutations (9 missense mutations, 7 splice site variants, 4 nonsense mutations, and 3 small insertions or deletions) and 7 intragenic deletions. Of these, 18 point mutations and 3 deletions are novel. Furthermore, our finding of four whole exon duplications enlarges the mutation spectrum in the ATP7A gene. ATP7A alterations were found in 85% of cases. Of these alterations, two thirds were point mutations and the remaining one third consisted of large rearrangements. We found that 66.6% of point mutations resulted in impaired ATP7A transcript splicing, a phenomenon more frequent than expected. This finding enabled us to confirm the pathogenic role of ATP7A mutations, particularly in missense and splice site variant

Asian-Pacific perspective on the psychological well-being of healthcare workers during the evolution of the COVID-19 pandemic

10.1192/bjo.2020.98BJPSYCH OPEN6