The role of interfaces in CoFe/IrMn exchange biased systems

A trilayer system consisting of an IrMn layer exchanged coupled to two CoFe layers of equal thickness has been studied. A single stage reversal was observed over a wide range of temperatures. Two bilayers with the same thicknesses of the pinning layer but different ferromagnetic thicknesses were also studied. By comparing the magnetic properties of these three stacks the effect of the interfacial area on the exchange field and the coercivity has been determined. We find that the interfacial area has a very minor effect on the exchange field H-ex and the blocking temperature (T-B) but causes a doubling of the coercivity (H-c). This indicates that H-c is dominated by the interface whereas the exchange bias is controlled by volumetric effects

Nuevos datos geocronológicos 40Ar-39Ar en dos puntos singulares del macizo de Anaga (Tenerife): Punta Poyata e Igueste de San Andrés. Consecuencias de interés

En este trabajo se aportan nuevos datos geocronológicos Ar40-Ar39 en rocas ancaramíticas submarinas localizadas en dos puntos singulares del macizo de Anaga (NE de Tenerife): las ancaramitas submarinas hidrotermalizadas de Punta Poyata (NNW de Anaga) y las lavas submarinas ancaramíticas del Barranco de Igueste (SE de Anaga). Las muestras estudiadas pertenecen a afloramientos pertenecientes a los niveles estratigráficos más inferiores de la secuencia volcánica que conforma el edificio de Anaga. En Punta Poyata se tomaron dos especímenes que dieron edades de 12,2 ± 1,9 Ma and 13,0 ± 1,0 Ma. En el barranco de Igueste los resultados geocronológicos de las muestras tomadas dieron edades de 12,7 ± 1,6 Ma and 9,7 ± 1,0 Ma. Estos datos sugieren que el macizo de Anaga comenzó su desarrollo subaéreo antes de lo que anteriormente se creía, ajustándose dicho período inicial al Mioceno Medio en lugar de al Mioceno tardío como previamente se asumía.This work provides new Ar40-Ar39 geochronological data in submarine ankaramite rocks located in two distant points of Anaga (NE Tenerife): the submarine hydrothermally altered ankaramites of Punta Poyata area (NNW Anaga) and the ankaramitic pillow lavas at Barranco de Igueste (SE Anaga). The studied samples were collected from outcrops of the lowest stratigraphic levels throughout the volcanics that build up the Anaga massif. At Punta Poyata, two collected samples yielded an age of 12,2 ± 1,9 Ma and 13,0 ± 1,0 Ma. At Barranco de Igueste, sample results are of 12,7 ± 1,6 Ma and 9,7 ± 1,0 Ma. These data support the assumption that the Anaga massif began its subaerial growth earlier than that previously was supposed, most likely in the Mid-Miocene Instead of late Miocene as currently believed.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Measurement of the anisotropy constant of antiferromagnets in metallic polycrystalline exchange biased systems

A method for the measurement of the anisotropy constant of the antiferromagnet (AF) KAF in exchange biased systems has been developed. This has been achieved by measurement of the median blocking temperature 〈TB〉 of a CoFe/IrMn bilayer. In thermal activation-free conditions, this is the temperature at which equal volumes of the AF are oriented in opposite senses. Hence, for a grain size dependent model, the critical volume for thermal activation at this point is equal to the median volume of the grain size distribution. A value of (5.5±0.5)×106 erg/cc has been obtained at room temperature for a 4 nm thick IrMn layer

Thermal instabilities in exchange biased materials

The use of antiferromagnetic (AF) materials to pin a soft ferromagnet (FM) in a spin-valve, read head, or MRAM cell, has focussed attention on the exchange bias phenomenon. We report on a study of the thermal stability of exchange bias systems, IrMn/CoFe and FeMn/NiFe, with different thicknesses and grain sizes. For these materials a temperature has been determined at which thermal activation does not affect the state of the antiferromagnet, leading to reproducible data. Grain size studies have shown that the coercivity and exchange bias have different origins. Training effects studied over a range of temperatures from 4.2 to 400 K indicate a range of different contributions to exchange bias from the magnetic state of the antiferromagnet

Comparison of intraocular pressure in eyes with macular edema treated with intravitreal triamcinolone acetonide with or without preservatives [Comparaci�n de la presi�n intraocular en ojos con edema macular tratados con acet�nido de triamcinolona intrav�trea con y sin conservadores]

Objective: To compare the incidence of ocular hypertension after the intravitreal injection of triamcinolone acetonide with and without preservative. Material and methods: Retrospective analysis of the clinical charts of patients with macular edema secondary to different pathologies. We established two groups. Group 1 included injected eyes with triamcinolone acetonide with preservative and group 2 included injected eyes with the preservative-free product. We compared the intraocular pressure at baseline and week 1, month 1 and month 3 after the intravitreal injection. Results: Ninety one eyes of eighty eight patients were included, 61 in group 1 and 30 in group 2. Elevation of the intraocular pressure after injection was higher for group 1, reaching statistic significance at all the corresponding measurements. In group 1, 36% of the eyes required medical or surgical treatment in order to control the intraocular pressure, while medical treatment was required only in 3% of the eyes included in group 2. Conclusions: Intravitreal injection of preservative-free triamcinolone acetonide induced lower incidence of ocular hypertension when compared to the formulation with preservative