From Chaos to Integrability in Double Scaled Sachdev-Ye-Kitaev Model via a Chord Path Integral.

We study thermodynamic phase transitions between integrable and chaotic dynamics. We do so by analyzing models that interpolate between the chaotic double scaled Sachdev-Ye-Kitaev (SYK) and the integrable p-spin systems, in a limit where they are described by chord diagrams. We develop a path integral formalism by coarse graining over the diagrams, which we use to argue that the system has two distinct phases: one is continuously connected to the chaotic system, and the other to the integrable.

Stress in centenarians.

Everybody is subject to a physical clock, determining the calendar age, and also to a biological clock, the speed of which depends on the interaction between the genetic reserves and the environment. Stress is taken into account more and more as one of the main factors responsible for the acceleration of the biological clock and the dishomogeneity of the aging process. Despite the fact that centenarians are prone to chronic stress due to a progressive loss of self-sufficiency, more than a half of our centenarians were not depressed and had a low trait-anxiety: they showed an emotional tendency to react with a low anxiety-intensity to stressful conditions.

Sleep quality of centenarians: cognitive and survival implications.

Sleep is an active nervous process, which is structured in phases characterized by subsequent cycles of various psycho-physiological phenomena. It performs vital, yet mysterious functions and is in all likelihood involved in many processes, including cognitive processes. In old age the internal structure of sleep changes, but these physiological variations allow, in healthy subjects, a satisfactory quantity and quality of sleep.