239 research outputs found
Thirty years of evidence on the efficacy of drug treatments for chronic heart failure with reduced ejection fraction: A network meta-analysis
Treatments that reduce mortality and morbidity in patients with heart failure with reduced ejection fraction, including angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), β-blockers (BB), mineralocorticoid receptor antagonists (MRA), and angiotensin receptor–neprilysin inhibitors (ARNI), have not been studied in a head-to-head fashion. This network meta-analysis aimed to compare the efficacy of these drugs and their combinations regarding all-cause mortality in patients with heart failure with reduced ejection fraction
Coherent information analysis of quantum channels in simple quantum systems
The coherent information concept is used to analyze a variety of simple
quantum systems. Coherent information was calculated for the information decay
in a two-level atom in the presence of an external resonant field, for the
information exchange between two coupled two-level atoms, and for the
information transfer from a two-level atom to another atom and to a photon
field. The coherent information is shown to be equal to zero for all
full-measurement procedures, but it completely retains its original value for
quantum duplication. Transmission of information from one open subsystem to
another one in the entire closed system is analyzed to learn quantum
information about the forbidden atomic transition via a dipole active
transition of the same atom. It is argued that coherent information can be used
effectively to quantify the information channels in physical systems where
quantum coherence plays an important role.Comment: 24 pages, 7 figs; Final versiob after minor changes, title changed;
to be published in Phys. Rev. A, September 200
From Reversible Quantum Microdynamics to Irreversible Quantum Transport
The transition from reversible microdynamics to irreversible transport can be
studied very efficiently with the help of the so-called projection method. We
give a concise introduction to that method, illustrate its power by using it to
analyze the well-known rate and quantum Boltzmann equations, and present, as a
new application, the derivation of a source term accounting for the spontaneous
creation of electron-positron pairs in strong fields. Thereby we emphasize the
fundamental importance of time scales: only if the various time scales
exhibited by the dynamics are widely disparate, can the evolution of the slower
degrees of freedom be described by a conventional Markovian transport equation;
otherwise, one must account for finite memory effects. We show how the
projection method can be employed to determine these time scales, and how --if
necessary-- it allows one to include memory effects in a straightforward
manner. Finally, there is an appendix in which we discuss the concepts of
entropy and macroscopic irreversibility.Comment: Review article, 78 pages, uuencoded compressed PostScript fil
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