Disciplinary publications from 2016
Abstract
We consider the diffusive properties of Brownian motion in a biased periodic potential. We relate the effective diffusion coefficient to the solution of two coupled time-independent partial differential equations and solve these equations numerically by the matrix-continued-fraction (MCF) method for intermediate values of the temperature and friction coefficient. The weak-noise limit is explored by numerical simulations of the Langevin equations. Here, we identify the regions of parameters for which the diffusion coefficient exponentially grows with inverse temperature. In particular, we demonstrate that there is a finite range of bias forces for which such a growth is observed (region of giant enhancement of diffusion). We also show that at small forces close to the critical range, the diffusion coefficient possesses a pronounced maximum as a function of temperature. All results can be interpreted in the framework of a simple two-state theory incorporating the transition rates between the locked and running solutions.
Abstract
Background: A wider subjective time horizon is assumed to be positively associated with longevity and vitality. In particular, a lifestyle with exposure to novel and varied information is considered beneficial for healthy cognitive aging. At present, measures that specifically assess individuals' perceived temporal extension to engage in active lifestyles in the future are not available.
Objectives: We introduce and validate a new self-report measure, the Subjective Health Horizon Questionnaire (SHH-Q). The SHH-Q assesses individuals' future time perspectives in relation to four interrelated but distinct lifestyle dimensions: (1) novelty-oriented exploration (Novelty), (2) bodily fitness (Body), (3) work goals (Work), and (4) goals in life (Life Goals). The present study aims at: (a) validating the hypothesized factor structure of the SHH-Q, according to which the SHH-Q consists of four interrelated but distinct subscales, and (b) testing the hypothesis that the Novelty and Body subscales of the SHH-Q show positive and selective associations with markers of cognition and somatic health, respectively.
Methods: Using structural equation modeling, we analyzed data from 1,371 healthy individuals (51% women) with a mean age of 70.1 years (SD = 3.6) who participated in the Berlin Aging Study II (BASE-II) and completed the SHH-Q.
Results: As predicted, the SHH-Q formed four correlated but distinct subscales: (1) Novelty, (2) Body, (3) Work, and (4) Life Goals. Greater self-reported future novelty orientation was associated with higher current memory performance, and greater future expectations regarding bodily fitness with better current metabolic status.
Conclusion: The SHH-Q reliably assesses individual differences in four distinct dimensions of future time perspective. Two of these dimensions, Novelty and Body, show differential associations with cognitive status and somatic health. The SHH-Q may serve as a tool to assess how different facets of future time perspective relate to somatic health, cognition, motivation, and affect, and may help to identify the socioeconomic and individual antecedents, correlates, and consequences of an active lifestyle.