Strong-Field Interaction With Bicircular and Elliptically Polarized Laser Pulses

Ultrafast physics, which encompasses phenomena occurring at the attosecond scale, provides the foundation for understanding electron dynamics in atoms, molecules, and materials. To explore this realm, ultrashort laser pulses are utilized as powerful tools for discerning dynamics and unraveling the underlying physics. By varying the laser polarization and employing pulse combinations, a wide range of intriguing ultrafast phenomena can be probed. In this thesis numerical simulations, specifically of the interaction of atoms with circularly and elliptically polarized pulses, are used to shed light on the fascinating dynamics exhibited by atoms when subjected to intense ultrafast laser irradiation. We first provide an overview of the dynamics that form the basis of the research conducted and the numerical methods employed to model the atom-laser interaction through the solution of the time-dependent Schrodinger equation. Building upon this foundation we then delve into the investigation of atoms interacting with bichromatic circularly polarized laser pulses. The distribution of population among various excited states is examined, and a new mechanism is proposed to explain the results. Next, we shift our focus to the analysis of photoelectron spectra generated by the ionization of atoms interacting with circularly and elliptically polarized pulses. The study specifically considers the effects of different initial magnetic states on the resulting spectra, shedding light on the underlying electron emission process. Lastly, we present two new numerical methods: A Monte Carlo simulation technique is introduced as a means to study electron dynamics and ionization in laser fields of long wavelengths. Second, an ab-initio solution for diatomic systems, based on the single-active-electron and Born-Oppenheimer approximations, is developed, applied, and tested.</p

Global Burden of Cardiovascular Diseases and Risk Factors, 1990-2019: Update From the GBD 2019 Study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases