Objectif Décrire les caractéristiques cliniques et démographiques des patients diabétiques de type 2 (DT2) débutant un traitement par un analogue du GLP-1 et les conditions de cette prescription en ...vie réelle en France. Matériels et méthodes Étude transversale, multicentrique, réalisée en 2013 auprès d’endocrinologues et de médecins généralistes (MG), chez les patients DT2 ini-tiant un traitement par GLP-1. Une analyse comparative avec les études d’enregistrement d’albiglutide (programme HARMONY) a été réalisée. Résultats 407 patients français ayant débuté un traitement par liraglutide (88,5 %) ou exénatide (11,5 %) ont été inclus: 314 (77 %) par des endocrinologues ( n = 73) et 93 (23 %) par des mg ( n = 67). 48 % étaient des hommes, d’âge moyen 59 ± 11 ans, avec une ancienneté moyenne du diabète de 11 ± 7 ans. Leur IMC moyen était de 33,6 ± 6,4 kg/m² avec 71 % de patients obèses, 24 % de patients en surpoids. Avant initiation de l’analogue du GLP-1, le dernier taux d’HbA1c était en moyenne de 8,7 ± 1,4 % et supérieur à 8 % pour 65 % des patients ; 76 % étaient traités par antidiabétiques oraux (ADO) seuls, 4 % par insuline seule et 20 % par insuline et ADO. L’analogue du GLP-1 était prescrit en association avec des ADO seuls (78 % des cas, le plus souvent en trithérapie) ou avec de l’insuline ± ADO (22 %). Le profil des patients de l’étude n’est pas apparu différent de celui des populations incluses dans le programme de développement de l’albiglutide, excepté pour l’âge. Conclusion Les analogues du GLP-1 sont la plupart du temps utilisés conformé-ment à leurs indications. De plus, le profil des patients en vie réelle correspond bien à celui observé dans les essais cliniques évaluant l’albiglutide. Déclaration d’intérêt Les auteurs déclarent avoir un intérêt avec un organisme privé, industriel ou commercial en relation avec le sujet présenté. Étude financée par GSK
Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are ...normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm(2)V(-1)S(-1)) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.
Abstract
Relativistic fermions in topological quantum materials are characterized by linear energy–momentum dispersion near band crossing points. Under magnetic fields, relativistic fermions acquire ...Berry phase of
π
in cyclotron motion, leading to a zeroth Landau level (LL) at the crossing point, a signature unique to relativistic fermions. Here we report the unusual interlayer quantum transport behavior resulting from the zeroth LL mode observed in the time reversal symmetry breaking type II Weyl semimetal YbMnBi
2
. The interlayer magnetoresistivity and Hall conductivity of this material are found to exhibit surprising angular dependences under high fields, which can be well fitted by a model, which considers the interlayer quantum tunneling transport of the zeroth LL's Weyl fermions. Our results shed light on the unusual role of zeroth LLl mode in transport.
Weyl (WSMs) evolve from Dirac semimetals in the presence of broken time-reversal symmetry (TRS) or space-inversion symmetry. The WSM phases in TaAs-class materials and photonic crystals are due to ...the loss of space-inversion symmetry. For TRS-breaking WSMs, despite numerous theoretical and experimental efforts, few examples have been reported. In this Article, we report a new type of magnetic semimetal Sr1-y Mn1-z Sb2 (y, z < 0.1) with nearly massless relativistic fermion behaviour (m∗ = 0.04 - 0.05m0 , where m0 is the free-electron mass). This material exhibits a ferromagnetic order for 304 K < T < 565 K, but a canted antiferromagnetic order with a ferromagnetic component for T < 304 K. The combination of relativistic fermion behaviour and ferromagnetism in Sr1-y Mn1-z Sb2 offers a rare opportunity to investigate the interplay between relativistic fermions and spontaneous TRS breaking.
The new alpha-Fe(Te,Se) superconductors share the common iron building block and ferminology with the LaFeAsO and BaFe(2)As(2) families of superconductors. In contrast with the predicted commensurate ...spin-density-wave order at the nesting wave vector (pi, 0), a completely different magnetic order with a composition tunable propagation vector (deltapi, deltapi) was determined for the parent compound Fe_{1+y}Te in this powder and single-crystal neutron diffraction study. The new antiferromagnetic order survives as a short-range one even in the highest T_{C} sample. An alternative to the prevailing nesting Fermi surface mechanism is required to understand the latest family of ferrous superconductors.
•We study the thermal hysteresis in spin-crossover nanoparticles with stochastic perturbation.•The dependence of system behavior on its dimensionality and size were examined.•The spin-crossover ...compounds where described by breathing crystal field Ising-like model.•The fluctuations may enlarge the hysteresis width which is dependent on the system size.
The spin-crossover nanoparticles of different sizes and stochastic perturbations in external field taking into account the influence of the dimensionality of the lattice was studied. The analytical tools used for the investigation of spin-crossover system are based on an Ising-like model described using of the breathing crystal field concept. The changes of transition temperatures characterizing the systems’ bistable properties for 2D and 3D lattices, and their dependence on its size and fluctuations strength were obtained. The state diagrams with hysteretic and non-hysteretic behavior regions have also been determined.
The recent breakthrough in the discovery of Weyl fermions in monopnictide semimetals provides opportunities to explore the exotic properties of relativistic fermions in condensed matter. The chiral ...anomaly-induced negative magnetoresistance and π Berry phase are two fundamental transport properties associated with the topological characteristics of Weyl semimetals. Since monopnictide semimetals are multiple-band systems, resolving clear Berry phase for each Fermi pocket remains a challenge. Here we report the determination of Berry phases of multiple Fermi pockets of Weyl semimetal TaP through high field quantum transport measurements. We show our TaP single crystal has the signatures of a Weyl state, including light effective quasiparticle masses, ultrahigh carrier mobility, as well as negative longitudinal magnetoresistance. Furthermore, we have generalized the Lifshitz-Kosevich formula for multiple-band Shubnikov-de Haas (SdH) oscillations and extracted the Berry phases of π for multiple Fermi pockets in TaP through the direct fits of the modified LK formula to the SdH oscillations. In high fields, we also probed signatures of Zeeman splitting, from which the Landé g-factor is extracted.
It is now well established that many of the technologically important properties of two-dimensional (2D) materials, such as the extremely high carrier mobility in graphene and the large direct band ...gaps in MoS2 monolayers, arise from quantum confinement. However, the influence of reduced dimensions on electron-phonon (e-ph) coupling and its attendant dephasing effects in such systems has remained unclear. Although phonon confinement is expected to produce a suppression of e-ph interactions in 2D systems with rigid boundary conditions, experimental verification of this has remained elusive. Here, we show that the e-ph interaction is, indeed, modified by a phonon dimensionality crossover in layered Nb3 SiTe6 atomic crystals. When the thickness of the Nb3 SiTe6 crystals is reduced below a few unit cells, we observe an unexpected enhancement of the weak-antilocalization signature in magnetotransport. This finding strongly supports the theoretically predicted suppression of e-ph interactions caused by quantum confinement of phonons.
Abstract
The effect of antiferromagnetic (AF) layer thickness on exchange bias was studied in a series of NiFe(50 nm)/FeMn(
t
) bilayers through both irreversible and reversible experiments at room ...temperature. The exchange bias was evaluated in the sample plane both through measurement of the major hysteresis loops and probing the reversible susceptibility. The critical curve was constructed to map the angular dependence of the magnetization switching and exchange bias, which is found to evolve as a function of AF layer thickness. Ferromagnetic resonance absorption was measured at several frequencies and angles, and angular-dependent absorption curves were plotted. A comparison is made between the recorded exchange bias using the three methods. The measurements reported are supported by simulations under a generalized Stoner–Wohlfarth model, and general limitations of the experiment are discussed.
The iron chalcogenide Fe(1+y)(Te(1-x)Se(x)) is structurally the simplest of the Fe-based superconductors. Although the Fermi surface is similar to iron pnictides, the parent compound Fe(1+y)Te ...exhibits antiferromagnetic order with an in-plane magnetic wave vector (pi,0). This contrasts the pnictide parent compounds where the magnetic order has an in-plane magnetic wave vector (pi,pi) that connects hole and electron parts of the Fermi surface. Despite these differences, both the pnictide and chalcogenide Fe superconductors exhibit a superconducting spin resonance around (pi,pi). A central question in this burgeoning field is therefore how (pi,pi) superconductivity can emerge from a (pi,0) magnetic instability. Here, we report that the magnetic soft mode evolving from the (pi,0)-type magnetic long-range order is associated with weak charge carrier localization. Bulk superconductivity occurs as magnetic correlations at (pi,0) are suppressed and the mode at (pi, pi) becomes dominant for x>0.29. Our results suggest a common magnetic origin for superconductivity in iron chalcogenide and pnictide superconductors. PUBLICATION ABSTRACT
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