The aging hippocampus: Interactions between exercise, depression, and BDNF

Late adulthood is associated with increased hippocampal atrophy and dysfunction. Although there are multiple paths by which hippocampal deterioration occurs in late life, the authors discuss the evidence that a single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene and age-related changes in BDNF protein or receptor expression contribute to hippocampal atrophy. The authors conclude that few studies have tested whether BDNF mediates age-related hippocampal atrophy and memory impairment. However, there is strong evidence that decreased BDNF is associated with age-related hippocampal dysfunction, memory impairment, and increased risk for depression, whereas increasing BDNF by aerobic exercise appears to ameliorate hippocampal atrophy, improve memory function, and reduce depression. Importantly, the most consistent associations between BDNF and hippocampal dysfunction have emerged from research on BDNF protein expression in rodents and serum and plasma concentrations of BDNF in humans. Current research suggests that the BDNF val66met polymorphism may be only weakly associated with hippocampal atrophy in late adulthood. These conclusions are interpreted in relation to age-related memory impairment and preventions for hippocampal atrophy. © SAGE Publications 2012

Accelerator Engineering and Technology: Accelerator Technology

Magnets are at the core of both circular and linear accelerators. The main function of a magnet is to guide the charged particle beam by virtue of the Lorentz force, given by the following expression:where q is the electrical charge of the particle, v its velocity, and B the magnetic field induction. The trajectory of a particle in the field depends hence on the particle velocity and on the space distribution of the field. The simplest case is that of a uniform magnetic field with a single component and velocity v normal to it, in which case the particle trajectory is a circle. A uniform field has thus a pure bending effect on a charged particle, and the magnet that generates it is generally referred to as a dipole