Magnetohydrodynamic turbulence regulates the transfer of energy from large to small scales in many astrophysical systems, including the solar atmosphere. We perform three-dimensional magnetohydrodynamic simulations with unprecedentedly large magnetic Reynolds number to reveal how rapid reconnection of magnetic field lines changes the classical paradigm of the turbulent energy cascade. By breaking elongated current sheets into chains of small magnetic flux ropes (or plasmoids), magnetic reconnection leads to a previously undiscovered range of energy cascade, where the rate of energy transfer is controlled by the growth rate of the plasmoids.
View Article and Find Full Text PDFNoncollisional current sheets that form during the nonlinear development of spontaneous magnetic reconnection are characterized by a small thickness, of the order of the electron skin depth. They can become unstable to the formation of plasmoids, which allows the magnetic reconnection process to reach high reconnection rates. In this work, we investigate the marginal stability conditions for the development of plasmoids when the forming current sheet is purely collisionless and in the presence of a strong guide field.
View Article and Find Full Text PDFNature's most powerful high-energy sources are capable of accelerating particles to high energy and radiating it away on extremely short timescales, even shorter than the light crossing time of the system. It is yet unclear what physical processes can produce such an efficient acceleration, despite the copious radiative losses. By means of radiative particle-in-cell simulations, we show that magnetically dominated turbulence in pair plasmas subject to strong synchrotron cooling generates a nonthermal particle spectrum with a hard power-law range (slope p∼1) within a few eddy turnover times.
View Article and Find Full Text PDFIn February 2017, the "Programma Mattone Internazionale Salute" (ProMis), that is the Italian Program for Internationalization of Regional Health Systems of the Ministry of Health (MoH), presented the first version of its Position Paper on Health Tourism, which embeds a first shared approach to the recommendations expressed by the European Committee of Regions (CoR) on "Age-Friendly" tourism. The CoR stresses the importance of local and regional authorities in the coordination of multi-sectoral policies such as healthcare, social assistance, transport, urban planning and rural development in relation to the promotion of mobility, security, accessibility of services, including health care and social services. "Age-friendly" tourism is an example of an innovative tourist offer that strives to meet the health needs of the entire "traveling" population, with an integrated and cross-sector approach that involves various organizations operating in sectors such as healthcare, accessibility and transport.
View Article and Find Full Text PDF