Youth Perspectives on Permanency

"What do foster youth think about permanency?" CPYP, in partnership with the California Youth Connection (CYC), held interviews and focus groups with several foster youth to talk about this question. This document explores some of their answers

Orbit control of asteroids in libration point orbits for resource exploitation

The fascinating idea of shepherding asteroids for science and resource utilisation is being considered as a very credible concept in a not too distant future. Past studies have identified asteroids which could be injected into manifolds which wind onto periodic orbits around collinear Lagrangian points of the Sun-Earth system, by means of a low-cost manoeuvre. However, the periodic orbits as well as the manifolds are highly unstable, and small errors in the capture manoeuvre would bring to complete mission failure, with potential danger of collision with the Earth itself. The main source of injection error in position and velocity is the epistemic uncertainty of the asteroid mass, which cannot be measured directly. For this reason, asteroid orbit control will be a strict requirement for such mission. This paper investigates the controllability of some asteroids during the transfer and along the period orbits, assuming the use of a solar-electric low-thrust engine. The control scheme is based on a linear quadratic regulator. A stochastic simulation with a Monte Carlo approach is used to simulate a range of different perturbed initial conditions. Results show that only a small subset of the considered combinations of trajectories/asteroids are reliably controllable, and therefore controllability must be taken into account in the selection of potential targets

External fluctuations in front dynamics with inertia: The overdamped limit

We study the dynamics of fronts when both inertial effects and external fluctuations are taken into account. Stochastic fluctuations are introduced as multiplicative noise arising from a control parameter of the system. Contrary to the non-inertial (overdamped) case, we find that important features of the system, such as the velocity selection picture, are not modified by the noise. We then compute the overdamped limit of the underdamped dynamics in a more careful way, finding that it does not exhibit any effect of noise either. Our result poses the question as to whether or not external noise sources can be measured in physical systems of this kind.Comment: 4 pages, 1 figure, accepted for publication in European Physical Journal

Hispanic-Owned businesses in West Michigan

Many vibrant neighborhoods in West Michigan have large, growing Hispanic populations. In fact, Hispanics are one of the fastest growing segments of West Michigan’s population, due to high immigration and birth rates. According to the U.S. Census, over 94,000 Hispanics lived in Kent, Ottawa, Muskegon, and Allegan Counties in 2006 — a little more than 7% of the total population — and that population has doubled since 1994. But the population of Hispanic individuals is not all that is growing. The number and variety of Hispanic-owned or Hispanic-focused businesses in Kent County is also increasing, evidenced by block after block of colorful retail storefronts on south Grandville Avenue (a.k.a. “Cesar E. Chávez Boulevard” for the legendary leader of migrant workers), on the west end of Bridge Street, and on South Division to 44th Street. There you will find an array of stores and services, from accountants and beauty shops to restaurants and supermarkets, most of which appear to be targeted to Spanish-speaking customers

Ancillary Documentation on the Union Army Migration Data set (UMAD)

migration; economic history; economics of aging