Trends in Stroke Prevention between 2014 and 2018 in Hospitalized Atrial Fibrillation Patients.

In recent years, significant changes in stroke prophylaxis in patients with atrial fibrillation (AF) have been observed. Non-vitamin K antagonist oral anticoagulants (NOACs) are more commonly used in the prevention of thromboembolic complications in patients with AF. The aim of the study was to evaluate recommended stroke prophylaxis in patients with AF and to identify predictors of using NOACs in patients treated with anticoagulant therapy. The present study was a retrospective, observational, single-center study which included consecutively hospitalized patients in the reference cardiology center from January 2014 to December 2018. In the study group of 4027 patients with AF, to prevent thromboembolic complications, OACs were used in 3680 patients (91.4%), an antiplatelet drug(s) was used in 124 patients (3.1%), and 223 patients (5.5%) did not undergo any thromboembolic event prevention. In the group of 3680 patients treated with OACs, 2311 patients (62.8%) received NOACs and 1639 patients (37.2%), VKAs. Independent predictors of the use of NOACs were age (OR, 1.02; 95% CI, 1.01-1.03; P < 0.001), a previous thromboembolic event (OR, 1.29; 95% CI, 1.01-1.65; P=0.04), nonpermanent AF (OR, 1.61; 95% CI, 1.34-1.93; P < 0.001), and eGFR (OR, 1.22; 95% CI, 1.02-1.46; P=0.03). Between 2014 and 2018, an increase of patients treated with OACs, mainly with NOACs, was observed. Age, past thromboembolic complications, nonpermanent AF, and preserved renal function determined the choice of NOACs.

Theoretical study of nitride short period superlattices.

Discussion of band gap behavior based on first principles calculations of electronic band structures for various short period nitride superlattices is presented. Binary superlattices, as InN/GaN and GaN/AlN as well as superlattices containing alloys, as InGaN/GaN, GaN/AlGaN, and GaN/InAlN are considered. Taking into account different crystallographic directions of growth (polar, semipolar and nonpolar) and different strain conditions (free-standing and pseudomorphic) all the factors influencing the band gap engineering are analyzed. Dependence on internal strain and lattice geometry is considered, but the main attention is devoted to the influence of the internal electric field and the hybridization of well and barrier wave functions. The contributions of these two important factors to band gap behavior are illustrated and estimated quantitatively. It appears that there are two interesting ranges of layer thicknesses; in one (few atomic monolayers in barriers and wells) the influence of the wave function hybridization is dominant, whereas in the other (layers thicker than roughly five to six monolayers) dependence of electric field on the band gaps is more important. The band gap behavior in superlattices is compared with the band gap dependence on composition in the corresponding ternary and quaternary alloys. It is shown that for superlattices it is possible to exceed by far the range of band gap values, which can be realized in ternary alloys. The calculated values of the band gaps are compared with the photoluminescence emission energies, when the corresponding data are available. Finally, similarities and differences between nitride and oxide polar superlattices are pointed out by comparison of wurtzite GaN/AlN and ZnO/MgO.

Band gap engineering of In(Ga)N/GaN short period superlattices.

Discussion of band gap behavior based on first principles calculations of the electronic band structures for several InN/GaN superlattices (SLs) (free-standing and pseudomorphic) grown along different directions (polar and nonpolar) is presented. Taking into account the dependence on internal strain and lattice geometry mainly two factors influence the dependence of the band gap, E g on the layer thickness: the internal electric field and the hyb wells) is more important. We also consider mIn ridization of well and barrier wave functions. We illustrate their influence on the band gap engineering by calculating the strength of built-in electric field and the oscillator strength. It appears that there are two interesting ranges of layer thicknesses. In one the influence of the electric field on the gaps is dominant (wider wells), whereas in the other the wave function hybridization (narrow wells) is more important. We also consider mIn 0.33 Ga 0.67 N/nGaN SLs, which seem to be easier to fabricate than high In content quantum wells. The calculated band gaps are compared with recent experimental data. It is shown that for In(Ga)N/GaN superlattices it is possible to exceed by far the range of band gap values, which can be realized in ternary InGaN alloys.