The Costs of Teenage Out-of-Wedlock Childbearing: Analysis with a Within-School Propensity Score Matching Estimator

Teen out-of-wedlock mothers have lower education and earnings than peers who have children later. This study uses the National Educational Longitudinal Survey of 1988 (NELS) to examine the extent to which the apparent effects of out-of-wedlock teen fertility are not causal, but are due to pre-existing disadvantages of the young women and their families. We use a novel fixed-effect matching method to study this problem. We find that mothers-to-be were substantially disadvantaged before their teen out-of-wedlock fertility. At the same time, we cannot rule out that out-of-wedlock fertility reduces education substantially, although far less than the cross-sectional comparisons of means suggest.

The new moral order and racism in South Africa post 11 September 2001

In this paper we argue that globalisation imposes on ‘developing’ countries more than an economic order; they find themselves with the moral imperative to align themselves with the West against its Others, increasingly portrayed as Islamic fundamentalists. The 11 September terror attacks in the United States of America have pushed this process to a new level, with the attacks represented as no less than a barbaric attack on ‘civilisation’. Through an analysis of a newspaper article reporting on the disciplining of a Muslim woman in for wearing an Osama Bin Laden t-shirt to work in South Africa, we indicate how this moral representation of the 11 September events and the Islamic Other have unique local effects. In South Africa it creates yet more possibilities for racialising practices to continue without being framed in explicitly racial terms. We further reflect on the implications of these events, and the complex interplay of the global and the local they demonstrate, for critical psychology in South Africa

Photonic Crystal Cavities and Waveguides

Recently, it has also become possible to microfabricate high reflectivity mirrors by creating two- and three-dimensional periodic structures. These periodic "photonic crystals" can be designed to open up frequency bands within which the propagation of electromagnetic waves is forbidden irrespective of the propagation direction in space and define photonic bandgaps. When combined with high index contrast slabs in which light can be efficiently guided, microfabricated two-dimensional photonic bandgap mirrors provide us with the geometries needed to confine and concentrate light into extremely small volumes and to obtain very high field intensities. Here we show the use of these "artificially" microfabricated crystals in functional nonlinear optical devices, such as lasers, modulators, and waveguides

Room temperature photonic crystal defect lasers at near-infrared wavelengths in InGaAsP

Room temperature lasing from optically pumped single defects in a two-dimensional (2-D) photonic bandgap (PBG) crystal is demonstrated. The high-Q optical microcavities are formed by etching a triangular array of air holes into a half-wavelength thick multiquantum-well waveguide. Defects in the 2-D photonic crystal are used to support highly localized optical modes with volumes ranging from 2 to 3 (lambda/2n)(3). Lithographic tuning of the air hole radius and the lattice spacing are used to match the cavity wavelength to the quantum-well gain peak, as well as to increase the cavity Q. The defect lasers were pumped with 10-30 ns pulses of 0.4-1% duty cycle. The threshold pump power was 1.5 mW (approximate to 500 μW absorbed)

Aggregation of biological particles under radial directional guidance

Many biological environments display an almost radially-symmetric structure, allowing proteins, cells or animals to move in an oriented fashion. Motivated by specific examples of cell movement in tissues, pigment protein movement in pigment cells and animal movement near watering holes, we consider a class of radially-symmetric anisotropic diffusion problems, which we call the star problem. The corresponding diffusion tensor D(x) is radially symmetric with isotropic diffusion at the origin. We show that the anisotropic geometry of the environment can lead to strong aggregations and blow-up at the origin. We classify the nature of aggregation and blow-up solutions and provide corresponding numerical simulations. A surprising element of this strong aggregation mechanism is that it is entirely based on geometry and does not derive from chemotaxis, adhesion or other well known aggregating mechanisms. We use these aggregate solutions to discuss the process of pigmentation changes in animals, cancer invasion in an oriented fibrous habitat (such as collagen fibres), and sheep distributions around watering holes

On the study of slow-fast dynamics, when the fast process has multiple invariant measures

Motivated by applications to mathematical biology, we study the averaging problem for slow-fast systems, {\em in the case in which the fast dynamics is a stochastic process with multiple invariant measures}. We consider both the case in which the fast process is decoupled from the slow process and the case in which the two components are fully coupled. We work in the setting in which the slow process evolves according to an Ordinary Differential Equation (ODE) and the fast process is a continuous time Markov Process with finite state space and show that, in this setting, the limiting (averaged) dynamics can be described as a random ODE (that is, an ODE with random coefficients.) Keywords. Multiscale methods, Processes with multiple equilibria, Averaging, Collective Navigation, Interacting Piecewise Deterministic Markov Processes.Comment: 24 page

Farnham rolls investigation

The object of this experiment was to investigate the possibility of obtaining pre-setting data for the 1 Farnham Rolls'. The experiment was carried out by applying certain deflections and measuring the resulting radii of curvature. Thus curves of curvature against deflection were produced for different sheet widths, and from these curves attempts to produce a conical frustum with prescribed radii were made. The results obtained can not be applied to conical parts, but this test served to indicate that it is possible to obtain pre-setting data for various applications

Comment "On the statistics of the product of a Gaussian process and a pseudo random binary code"

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Socialist Women and the Great War, 1914-21: Protest, Revolution and Commemoration

Socialist Women and the Great War: Protest, Revolution and Commemoration, an open access book, is the first transnational study of left-wing women and socialist revolution during the First World War and its aftermath. Through a discussion of the key themes related to women and revolution, such as anti-militarism and violence, democracy and citizenship, and experience and life-writing, this book sheds new and necessary light on the everyday lives of socialist women in the early 20th century. The participants of the 1918-1919 revolutions in Europe, and the accompanying outbreaks of social unrest elsewhere in the world, have typically been portrayed as war-weary soldiers and suited committee delegates—in other words, as men. Exceptions like Rosa Luxemburg exist, but ordinary women are often cast as passive recipients of the vote. This is not true; rather, women were pivotal actors in the making, imagining, and remembering of the social and political upheavals of this time. From wartime strikes, to revolutionary violence, to issues of suffrage, this book reveals how women constructed their own revolutionary selves in order to bring about lasting social change and provides a fresh comparative approach to women's socialist activism. As such, this is a vitally important resource for all postgraduates and advanced undergraduates interested in gender studies, international relations, and the history and legacy of World War I. The ebook editions of this book are available open access under a CC BY-NC-ND 4.0 licence on bloomsburycollection.com. Open access was funded by Knowledge Unlatched

Feasibility of detecting single atoms using photonic bandgap cavities

We propose an atom-cavity chip that combines laser cooling and trapping of neutral atoms with magnetic microtraps and waveguides to deliver a cold atom to the mode of a fiber taper coupled photonic bandgap (PBG) cavity. The feasibility of this device for detecting single atoms is analyzed using both a semi-classical treatment and an unconditional master equation approach. Single-atom detection seems achievable in an initial experiment involving the non-deterministic delivery of weakly trapped atoms into the mode of the PBG cavity.Comment: 11 pages, 5 figure