It is well established that the longitudinal component of paraxial optical vortices has a key role in specific atomic quadrupole transitions near the beam axis when the spin and orbital angular momenta are antiparallel. By deriving analytical expressions for the position-dependent selection rules, this work shows that the significant role of the longitudinal fields is not limited to this case, but rather is a more general feature for any paraxial light including, for example, optical vortices with parallel spin and orbital angular momenta as well as Guassian beams. Numerically, the transition strengths induced by the weaker longitudinal component can be twice as high as those by the stronger transverse component.
View Article and Find Full Text PDFNeural Comput Appl
August 2022
COVID-19 is an infectious disease with its first recorded cases identified in late 2019, while in March of 2020 it was declared as a pandemic. The outbreak of the disease has led to a sharp increase in posts and comments from social media users, with a plethora of sentiments being found therein. This paper addresses the subject of sentiment analysis, focusing on the classification of users' sentiment from posts related to COVID-19 that originate from Twitter.
View Article and Find Full Text PDFNanomaterials (Basel)
August 2020
Hybrid nanoplasmonic systems can provide a promising platform of potential nonlinear applications due to the enhancement of optical fields near their surfaces in addition to the control of strong light-matter interactions they can afford. We theoretically investigated the optical multistability of a probe field that circulated along a unidirectional ring cavity containing a metal nanoparticle-graphene nanodisk-quantum dot hybrid system; the quantum dot was modeled as a three-level atomic system of Lambda configuration interacting with probe and control fields in the optical region of the electromagnetic spectrum. We show that the threshold and degree of multistability can be controlled by the geometry of the setup, the size of metal nanoparticles, the carrier mobility in the graphene nanodisk and the detunings of probe and control fields.
View Article and Find Full Text PDFArch Med Sci
May 2020
Introduction: The use of generic drugs is continuously growing; however, there are limited epidemiological data regarding the therapeutic equivalence of each original drug formulation with its generic counterparts. We evaluated the 12-month composite endpoint of recurrent acute myocardial infarction, ischaemic stroke, cardiac deaths, or hospitalisation due to a major bleeding in acute coronary syndrome (ACS) patients treated with original clopidogrel or a generic clopidogrel formulation, in relation to sociodemographic and clinical characteristics.
Material And Methods: Consecutive Greek ACS patients ( = 1194) hospitalised in the Aegean islands and the Attica region were enrolled.