Atrial Fibrillation and Hypertension: “Quo Vadis”

Hypertension is one of the most well-established risk factors for atrial fibrillation. Long-standing untreated hypertension leads to structural remodeling and electrophysiologic alterations causing an atrial myopathy that forms a vulnerable substrate for the development and maintenance of atrial fibrillation. Hypertension-induced hemodynamic, inflammatory, hormonal, and autonomic changes all appear to be important contributing factors. Furthermore, hypertension is also associated with several atrial fibrillation-related comorbidities. As such, hypertension may represent an important target for therapy in atrial fibrillation. Clinicians should be aware of pitfalls of the blood pressure measurement in atrial fibrillation. While the auscultatory method is preferred, the use of automated devices appears to be an acceptable method in the ambulatory setting. There are pathophysiologic bases and emerging clinical evidence suggesting the benefit of renin-angiotensin system inhibition in risk reduction of atrial fibrillation development particularly in patients with left ventricular hypertrophy or left ventricular dysfunction. A better understanding of hypertension’s pathophysiologic link to atrial fibrillation may lead to the development of novel therapies for the primary prevention of atrial fibrillation. Finally, future studies are needed to address optimal blood pressure goal to minimize the risk of atrial fibrillation-related complications.

Quo Vadis Nonlinear Optics? An Alternative and Simple Approach to Third Rank Tensors in Semiconductors

It is well understood that nonlinear optical (NLO) phenomena are deeply related to the material’s symmetry. Mathematically, the material symmetry can be described in terms of the nonzero parameters in the nonlinear susceptibility tensors. Generally, more complex structures involve more nonzero parameters in the tensor. The number of parameters increases rapidly if higher NLO orders are considered, complicating the physical analysis. Conventionally, these parameters are obtained via abstract symmetry analysis, e.g., group theory (GT). This work presents a novel theoretical analysis to approach the nonlinear tensor using the simplified bond hyperpolarizability model (SBHM) and compare it with GT. Our analysis is based on a light–matter interaction classical phenomenological physical framework. Rather than just looking at the symmetry of the crystal, the model applies physical considerations requiring fewer independent parameters in the tensor than GT. Such a simplification significantly improves the determination of the surface–bulk SHG contribution factors, which cannot be extracted from the experiment alone. We also show for the case of perovskite that the SHG contribution can be addressed solely from their surface dipoles with only one independent component in the tensor. Therefore, this work may open the path for a similar analysis in other complicated semiconductor surfaces and structures in the future, with potential applications to nanoscale surface characterization and real-time surface deposition monitoring.