ABSTRACT
We report on laser cooling of a large fraction of positronium (Ps) in free flight by strongly saturating the 1^{3}S-2^{3}P transition with a broadband, long-pulsed 243 nm alexandrite laser. The ground state Ps cloud is produced in a magnetic and electric field-free environment. We observe two different laser-induced effects. The first effect is an increase in the number of atoms in the ground state after the time Ps has spent in the long-lived 2^{3}P states. The second effect is one-dimensional Doppler cooling of Ps, reducing the cloud's temperature from 380(20) to 170(20) K. We demonstrate a 58(9)% increase in the fraction of Ps atoms with v_{1D}<3.7×10^{4} ms^{-1}.
ABSTRACT
Hepatopulmonary syndrome (HPS) is a complication of liver cirrhosis and is responsible for chronic hypoxemia and its negative health consequences. The most relevant diagnostic criterion of HPS is evidence of pathological intrapulmonary blood shunting (IPBS). There is still insufficient knowledge about the subclinical forms of HPS. The aim of this study was to determine whether an erect posture in patients with liver cirrhosis had a significant effect on IPBS, the diagnosis of HPS and oxygen saturation. Thirty cirrhotic patients considered for liver transplantation were enrolled in this study. Pulse oximetry and lung perfusion scintigraphy were conducted in patients while they were in supine and upright body positions. Pathological IPBS was observed in 16% and 20% of patients examined in the supine and upright body positions, respectively (mean difference 0.59%; P = 0.046). Postural-related IPBS changes were markedly greater in patients with HPS (1.76%; P = 0.011). Oxygen saturation was significantly lower in the erect posture compared to the supine posture (mean difference 1.2%; P = 0.02); however, there was no relationship between oxygen saturation and IPBS. In conclusion, an erect posture in patients with advanced liver cirrhosis leads to a subtle increase in IPBS, which is more pronounced in patients with HPS, and oxygen saturation measurements are not sensitive enough to detect these changes.
Subject(s)
Hepatopulmonary Syndrome/physiopathology , Liver Cirrhosis/physiopathology , Lung/physiopathology , Posture/physiology , Pulmonary Circulation/physiology , Adult , Aged , Female , Hepatopulmonary Syndrome/etiology , Humans , Liver Cirrhosis/complications , Lung/blood supply , Male , Middle Aged , Oximetry , Perfusion Imaging , Young AdultABSTRACT
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.
