The Lorentz transformations of propagation-invariant localized waves (also known as nondispersive or nondiffracting or undistorted progressive waves) are studied in the frequency-momentum space. For supports of wave functions in this space rules of transformation are derived which allow one to group all localized waves into distinct classes: subluminal, luminal, and superluminal localized waves. It is shown that for each class there is an inertial frame in which any given localized wave takes a particularly simple form. In other words, any localized wave is nothing but a relativistically aberrant and Doppler shifted version of a simple "seed" wave. Also discussed are the relations of the physical (subluminal) Lorentz tranformation to other mathematical tranformations used in the literature on localized waves, as well as physical interpretation of the substantial changes that localized waves undergo if observed and generated in different inertial frames.
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http://dx.doi.org/10.1103/PhysRevE.69.036612 | DOI Listing |
Confl Health
January 2025
London School of Hygiene and Tropical Medicine, Department of Non-Communicable Diseases Epidemiology, Keppel street, London, WC1E 7HT, UK.
Background: Non-communicable diseases (NCDs) are the leading cause of death globally, and many humanitarian crises occur in countries with high NCD burdens. Peer support is a promising approach to improve NCD care in these settings. However, evidence on peer support for people living with NCDs in humanitarian settings is limited.
View Article and Find Full Text PDFBMC Health Serv Res
January 2025
Institute of Health and Care Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Introduction: The COVID-19 pandemic forced leaders and employees in health care services to take difficult decisions to manage risks associated with employee health and the organizations' functioning. This study aims to identify the changes in employee working routines, job demands, and job resources within Swedish maternal healthcare during the COVID-19 pandemic, and how these changes affected workload and health.
Methods: Data were derived from the longitudinal COPE Staff study involving midwives and physicians within maternal healthcare.
JACC Clin Electrophysiol
January 2025
Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA; Duke Clinical Research Institute, Durham, North Carolina, USA. Electronic address:
Background: In patients with structurally normal hearts, algorithms using surface electrocardiographic P-wave morphology are helpful to predict focal atrial tachycardia (FAT) location. However, these algorithms have not been formally assessed in patients with adult congenital heart disease (ACHD).
Objectives: This study sought to assess the efficacy of FAT-location prediction algorithms in an adult population of patients with ACHD.
Phys Rev Lett
December 2024
Institut Langevin, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France.
The interaction between waves and evolving media challenges traditional conservation laws. We experimentally investigate the behavior of elastic wave packets crossing a moving interface that separates two media with distinct propagation properties, observing the noninvariance of wavelength and frequency. Our experimental setup employs an elastic strip whose local stretching can be dynamically altered by pulling one end at a constant velocity.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
MSC, CNRS, Université Paris Cité, UMR 7057, F-75013 Paris, France.
We report on the dynamics of a soliton propagating on the surface of a fluid in a 4-m-long canal with a random or periodic bottom topography. Using a full space-and-time resolved wave field measurement, we evidence, for the first time experimentally, how the soliton is affected by the disorder, in the context of Anderson localization, and how localization depends on nonlinearity. For weak soliton amplitudes, the localization length is found in quantitative agreement with a linear shallow-water theory.
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