The secular perturbations exerted by an inclined satellite orbiting in a gap in a broad planetary ring tends to excite the inclinations of the nearby ring particles, and the ring’s self–gravity can allow that disturbance to propagate away in the form of a spiral bending wave. The amplitude of this spiral bending wave is determined, as well as the wavelength, which shrinks as the waves propagate...

BACKGROUND U.S. epidemiologic surveys have consistently found higher lifetime prevalence of alcohol dependence among younger subjects than among older groups. Because lifetime prevalence is cumulative, such patterns are suggestive of strong secular trends; i.e., more-recently born subjects have developed more disease in a shorter period of time than their elders. However, it remains unclear whe...

Statural growth is dependent on hereditary and environmental factors, i.e disease, nutrition. The improvement of socioeconomic conditions that took place during the 20th century resulted in a secular trend towards greater height and earlier sexual maturation. Greek society has changed dramatically from a mainly agricultural society at the beginning of the 20th century to a mainly urban one in t...

BACKGROUND/OBJECTIVES Although secular trends have been well documented in the craniofacial region, there is no evidence to suggest that these temporal changes exist in samples used for orthodontic research. The aim of this study is to determine the effect of secular trends on craniofacial growth in a series of longitudinal birth cohorts that are frequently used in orthodontic research. MATER...