Using improved, up–to–date stellar input physics tested against observations of low– mass stars and brown dwarfs we calculate the secular evolution of low–mass donor cat-aclysmic variables (CVs), including those which form with a brown dwarf donor. Our models confirm the mismatch between the calculated minimum period (P min ≃ 70 min) and the observed short–period cut–off (≃ 80 min) in the CV pe...

We investigate heat transport in a spin-1/2 Heisenberg chain, coupled locally to independent thermal baths of different temperature. The analysis is carried out within the framework of the theory of open systems by means of appropriate quantum master equations. The standard microscopic derivation of the weak-coupling Lindblad equation in the secular approximation is considered, and shown to be ...

Diabetes is a complex disease characterized by chronic hyperglycemia and multiple phenotypes. In 1995, we used a doctor-nurse-clerk team and structured protocol to establish the Hong Kong Diabetes Registry in a quality improvement program. By 2009, we had accrued 2616 clinical events in 9588 Chinese type 2 diabetic patients with a follow-up duration of 6 years. The detailed phenotypes at enroll...

BACKGROUND Diet is an important factor in the prevention of chronic diseases. Analysis of secular trends of dietary patterns can be biased by energy under-reporting. Therefore, the objective of the present study was to analyse the impact of energy under-reporting on dietary patterns and secular trends in dietary patterns defined by cluster analysis. DESIGN AND METHODS Two cross-sectional popu...

OBJECTIVE There is little epidemiologic research on longitudinal and secular trends in weight-related health behaviors throughout the stages of adolescence. In particular, few data are available to assess secular trends in various sedentary behaviors. The objective of this research was to investigate longitudinal and secular trends in physical activity and sedentary behavior in a large, diverse...

The problem min x ‖x‖, s.t. ‖b−Ax‖ ≤ arises in the regularization of discrete forms of ill-posed problems when an estimate of the noise level in the data is available. After deriving necessary and sufficient optimality conditions for this problem, we propose two different classes of algorithms: a factorization-based algorithm for small to medium problems, and matrix-free iterations for the larg...

One-armed oscillation modes in the circumstellar discs of Be stars may explain the cyclical variations in their emission lines. We show that a three-dimensional effect, involving vertical motion and neglected in previous treatments, profoundly influences the dynamics. Using a secular theory of eccentric discs that reduces the problem to a second-order differential equation, we show that confine...

The Poynting-Robertson (P-R) effect has been applied to meteoroids – interplanetary dust particles – for several decades. It is well known that the P-R effect produces only changes in the orbital plane of the particle. Provided the initial orbits are not near circular, the differential equations governing the secular changes in both eccentricity and semimajor axis have been known since the time...