Stability of the flow around a cylinder: The spin-up problem

A concern is the flow around an infinite cylinder, which at a certain instant impulsively starts to spin. The growth of vortices in the resulting boundary layer occurring outside the cylinder is investigated. This layer is essentially a Rayleigh layer which grows with time, so the mechanism involved is similar to that studied in Hall (1983). Vortices with wavenumber comparable to the layer thickness are shown to be described by partial differential equations that govern the system numerically. It is assumed that the Rayleigh layer is thin, so particles are confined to move in a path with radius of curvature the same as the cylinder. The Goertler number is a function of time, so the time scale which produces an order, is considered one Goertler number. The right hand branch calculation is considered by letting the time tend to infinity, also inviscid Goertler modes are considered

Institutions and the transition to adulthood: Implications for fertility tempo in low-fertility settings

The number of countries experiencing very low fertility has been rising in recent years, garnering increasing academic, political and media attention. There is now widespread academic agreement that the postponement of fertility is a major contributing factor in the very low levels of fertility that have occurred, and yet most policy discussions have been devoted to increasing the numbers of children women have. We discuss factors in three institutions--the educational system, the labour market and the housing market--that may inadvertently have led to childbearing postponement. We highlight important components of the timing of childbearing, including its changing place within the transition to adulthood across countries and the significance of the demands of childbearing versus childrearing. Using illustrations from Europe, North America, Japan, Australia and New Zealand, we argue that the following all lead to younger childbearing: 1) an open education system whereby it is relatively easy to return to school after having dropped out for a while; 2) a shorter, smoother, easier school-to-work transition; 3) easier re-entry into the labour market after having taken time out for childrearing or any other reason; 4) greater capability of integrating childrearing into a career; 5) easier ability to obtain a mortgage with a moderately small down payment, moderately low interest rate and a long time period over which to repay the loan; and 6) easier ability to rent a dwelling unit at an affordable price. Conversely, reversing any or all of these factors would lead, other things being equal, to postponement of childbearing.

Analysis of phase transitions in the mean-field Blume-Emery-Griffiths model

In this paper we give a complete analysis of the phase transitions in the mean-field Blume-Emery-Griffiths lattice-spin model with respect to the canonical ensemble, showing both a second-order, continuous phase transition and a first-order, discontinuous phase transition for appropriate values of the thermodynamic parameters that define the model. These phase transitions are analyzed both in terms of the empirical measure and the spin per site by studying bifurcation phenomena of the corresponding sets of canonical equilibrium macrostates, which are defined via large deviation principles. Analogous phase transitions with respect to the microcanonical ensemble are also studied via a combination of rigorous analysis and numerical calculations. Finally, probabilistic limit theorems for appropriately scaled values of the total spin are proved with respect to the canonical ensemble. These limit theorems include both central-limit-type theorems when the thermodynamic parameters are not equal to critical values and non-central-limit-type theorems when these parameters equal critical values.Comment: 33 pages, revtex

Design and fabrication of a full-size landing impact test model of the Mars legged lander configuration Master agreement, task order three

Design and fabrication of full size landing impact test model of Mars legged lander configuratio

Photodetachment of cold OH- in a multipole ion trap

The absolute photodetachment cross section of OH- anions at a rotational and translational temperature of 170K is determined by measuring the detachment-induced decay rate of the anions in a multipole radio-frequency ion trap. In comparison with previous results, the obtained cross section shows the importance of the initial rotational state distribution. Using a tomography scan of the photodetachment laser through the trapped ion cloud, the derived cross section is model-independent and thus features a small systematic uncertainty. The tomography also yields the column density of the OH- anions in the 22-pole ion trap in good agreement with the expected trapping potential of a large field free region bound by steep potential walls.Comment: Phys. Rev. Lett., in pres

EFFECT OF CONTACT ANGLE AND TANK GEOMETRY ON THE CONFIGURATION OF THE LIQUID-VAPOR INTERFACE DURING WEIGHTLESSNESS

Effect of contact angle and space vehicle tank geometry on configuration of rocket propellant liquid-vapor interface during weightlessnes