Livres sur le sujet « Wave localization »

After its implementation in 1980, shock wave lithotripsy (SWL) became the first-line treatment for more than 80% of patients with urolithiasis. During the last three decades, SWL technology has advanced rapidly in terms of shock wave generation, focusing, patient coupling, and stone localization. Indications for SWL have evolved as well. Although endoscopic treatment techniques continue to improve, SWL continues to be considered first-line therapy for the treatment of many urinary stones. This chapter reviews the fundamental principles of SWL and presents advances in lithotripsy technology such as shock wave generation and focusing, advances in stone localization (imaging), different energy source concepts, and coupling modalities. Our understanding of the pathophysiology and the physics of shock waves can enhance extracorporeal SWL efficacy while limiting complications. Finally, current indications for and contraindications to SWL depending on stone location and in context of the updated AUA/EAU Guidelines are discussed.

This article discusses some applications of concepts from random matrix theory (RMT) to condensed matter physics, with emphasis on phenomena, predicted or explained by RMT, that have actually been observed in experiments on quantum wires and quantum dots. These observations range from universal conductance fluctuations (UCF) to weak localization, non-Gaussian thermopower distributions, and sub-Poissonian shot noise. The article first considers the UCF phenomenon, nonlogarithmic eigenvalue repulsion, and sub-Poissonian shot noise in quantum wires before analysing level and wave function statistics, scattering matrix ensembles, conductance distribution, and thermopower distribution in quantum dots. It also examines the effects (not yet observed) of superconductors on the statistics of the Hamiltonian and scattering matrix.

The atmospheric circulation in the mid-latitudes of both hemispheres is usually dominated by westerly winds and by planetary-scale and shorter-scale synoptic waves, moving mostly from west to east. A remarkable and frequent exception to this “usual” behavior is atmospheric blocking. Blocking occurs when the usual zonal flow is hindered by the establishment of a large-amplitude, quasi-stationary, high-pressure meridional circulation structure which “blocks” the flow of the westerlies and the progression of the atmospheric waves and disturbances embedded in them. Such blocking structures can have lifetimes varying from a few days to several weeks in the most extreme cases. Their presence can strongly affect the weather of large portions of the mid-latitudes, leading to the establishment of anomalous meteorological conditions. These can take the form of strong precipitation episodes or persistent anticyclonic regimes, leading in turn to floods, extreme cold spells, heat waves, or short-lived droughts. Even air quality can be strongly influenced by the establishment of atmospheric blocking, with episodes of high concentrations of low-level ozone in summer and of particulate matter and other air pollutants in winter, particularly in highly populated urban areas.Atmospheric blocking has the tendency to occur more often in winter and in certain longitudinal quadrants, notably the Euro-Atlantic and the Pacific sectors of the Northern Hemisphere. In the Southern Hemisphere, blocking episodes are generally less frequent, and the longitudinal localization is less pronounced than in the Northern Hemisphere.Blocking has aroused the interest of atmospheric scientists since the middle of the last century, with the pioneering observational works of Berggren, Bolin, Rossby, and Rex, and has become the subject of innumerable observational and theoretical studies. The purpose of such studies was originally to find a commonly accepted structural and phenomenological definition of atmospheric blocking. The investigations went on to study blocking climatology in terms of the geographical distribution of its frequency of occurrence and the associated seasonal and inter-annual variability. Well into the second half of the 20th century, a large number of theoretical dynamic works on blocking formation and maintenance started appearing in the literature. Such theoretical studies explored a wide range of possible dynamic mechanisms, including large-amplitude planetary-scale wave dynamics, including Rossby wave breaking, multiple equilibria circulation regimes, large-scale forcing of anticyclones by synoptic-scale eddies, finite-amplitude non-linear instability theory, and influence of sea surface temperature anomalies, to name but a few. However, to date no unique theoretical model of atmospheric blocking has been formulated that can account for all of its observational characteristics.When numerical, global short- and medium-range weather predictions started being produced operationally, and with the establishment, in the late 1970s and early 1980s, of the European Centre for Medium-Range Weather Forecasts, it quickly became of relevance to assess the capability of numerical models to predict blocking with the correct space-time characteristics (e.g., location, time of onset, life span, and decay). Early studies showed that models had difficulties in correctly representing blocking as well as in connection with their large systematic (mean) errors.Despite enormous improvements in the ability of numerical models to represent atmospheric dynamics, blocking remains a challenge for global weather prediction and climate simulation models. Such modeling deficiencies have negative consequences not only for our ability to represent the observed climate but also for the possibility of producing high-quality seasonal-to-decadal predictions. For such predictions, representing the correct space-time statistics of blocking occurrence is, especially for certain geographical areas, extremely important.

Philip W. Anderson (1923–2020) is widely regarded as one of the most accomplished and influential physicists of the second half of the twentieth century. Educated at Harvard, he served during World War II as a radar engineer, and began a thirty-five year career at Bell Laboratories in 1949. He was soon recognized as one of the pre-eminent theoretical physicists in the world, specializing in understanding the collective behavior of the vast number of atoms and electrons in a sample of solid matter. He won a one-third share of the 1977 Nobel Prize for Physics for his discovery of a phenomenon common to all waves in disordered matter called Anderson localization and the development of the Anderson impurity model to study magnetism. At Cambridge and Princeton Universities, Anderson led the way in transforming solid-state physics into the deep, subtle, and coherent discipline known today as condensed matter physics. He developed the concepts of broken symmetry and emergence and championed the concept of complexity as an organizing principle to attack difficult problems inside and outside physics. In 1971, Anderson was the first scientist to challenge the claim of high-energy particle physicists that their work was the most deserving of federal funding. Later, he testified before Congress opposing the Superconducting Super Collider particle accelerator. Anderson was a dominant figure in his field for almost fifty years. At an age when most scientists think about retirement, he made a brilliant contribution to many-electron theory and applied it to a novel class of high-temperature superconductors.