Does specification matter? Experiments with simple multiregional probabilistic population projections

Population projection models that introduce uncertainty are a growing subset of projection models in general. In this paper, we focus on the importance of decisions made with regard to the model specifications adopted. We compare the forecasts and prediction intervals associated with four simple regional population projection models: a total growth rate model, a component model with net migration, a component model with in-migration and outmigration rates, and a multiregional model with destination-specific out-migration rates. Vector autoregressive models are used to forecast future rates of growth, birth, death, net migration, in-migration and out-migration, and destination-specific out-migration for the North, Midlands and South regions in England (additional specification decisions once again come into play). They are also used to forecast different international migration measures. The base data represent a time series of annual data provided by the Office for National Statistics from 1976 to 2008. The results illustrate how both the forecasted subpopulation totals and the corresponding prediction intervals differ for the multiregional model in comparison to other simpler models, as well as for different assumptions about international migration. The paper ends end with a discussion of our results and possible directions for future researc

Improving estimates of migration flows to Eurostat

In this paper we identify the current mandatory requirements and issues concerning the supply of detailed migration data to Eurostat. Using simple illustrations on immigration to the United Kingdom, we show how substantial and significant improvements can be made to the flows reported by the International Passenger Survey, which contain irregularities and missing data due to its relatively small sample size. Our general methodology is based on the idea of smoothing, repairing and combining data within multiplicative component framework

A Study of Arts Education in the State of Illinois

The purpose of this study is to reveal the past position and present status of arts programs in general education for the state of Illinois. For the past two decades, the arts have experienced tremendous cutbacks and a general lack of support. This study discloses Illinois\u27 course of action for developing, expanding, and advocating the arts in general education. The introduction to this study is designed to provide helpful background information on the state of the arts on the national level in order to compare similar problems and progress as achieved by the state of Illinois. Beginning with the year 1978, a study of the historical background of the state of the arts in Illinois education is combined with a brief examination of the current status of the arts in Illinois\u27 education in Section Two. These findings reveal the need for maintaining and promoting the arts in general education. The body of this study encompasses Section Three. This section contains Illinois\u27 approach to advancing, expanding, and promoting its arts programs. Included in this section is the state\u27s arts plan which embraces its resolutions, its philosophy, and its attitudes toward the important roles the arts play in general education. This particular part of the study incorporates Illinois\u27 Comprehensive Arts Education Program and its six components: Generalized Arts Instruction, Traditional Arts Instruction, Integrated Arts Instruction, Interrelated Arts Instruction, Specialized Arts Instruction, and Extended Arts Instruction. Each component is discussed along with actual examples of implementation in Illinois school districts. The conclusion summarizes these findings. This closing segment presents research which emphasizes the strong need to advocate Illinois arts education and national arts education as basic and essential within the general curriculum

What do Bayesian methods offer population forecasters?

The Bayesian approach has a number of attractive properties for probabilistic forecasting. In this paper, we apply Bayesian time series models to obtain future population estimates with uncertainty for England and Wales. To account for heterogeneity found in the historical data, we add parameters to represent the stochastic volatility in the error terms. Uncertainty in model choice is incorporated through Bayesian model averaging techniques. The resulting predictive distributions from Bayesian forecasting models have two main advantages over those obtained using traditional stochastic models. Firstly, data and uncertainties in the parameters and model choice are explicitly included using probability distributions. As a result, more realistic probabilistic population forecasts can be obtained. Second, Bayesian models formally allow the incorporation of expert opinion, including uncertainty, into the forecast. Our results are discussed in relation to classical time series methods and existing cohort component projections. This paper demonstrates the flexibility of the Bayesian approach to simple population forecasting and provides insights into further developments of more complicated population models that include, for example, components of demographic change

Modematching an optical quantum memory

We analyse the off-resonant Raman interaction of a single broadband photon, copropagating with a classical `control' pulse, with an atomic ensemble. It is shown that the classical electrodynamical structure of the interaction guarantees canonical evolution of the quantum mechanical field operators. This allows the interaction to be decomposed as a beamsplitter transformation between optical and material excitations on a mode-by-mode basis. A single, dominant modefunction describes the dynamics for arbitrary control pulse shapes. Complete transfer of the quantum state of the incident photon to a collective dark state within the ensemble can be achieved by shaping the control pulse so as to match the dominant mode to the temporal mode of the photon. Readout of the material excitation, back to the optical field, is considered in the context of the symmetry connecting the input and output modes. Finally, we show that the transverse spatial structure of the interaction is characterised by the same mode decomposition.Comment: 17 pages, 4 figures. Brief section added treating the transverse spatial structure of the memory interaction. Some references added. A few typos fixe

Quantum Frequency Translation of Single-Photon States in Photonic Crystal Fiber

We experimentally demonstrate frequency translation of a nonclassical optical field via the Bragg scattering four-wave mixing process in a photonic crystal fiber (PCF). The high nonlinearity and the ability to control dispersion in PCF enable efficient translation between photon channels within the visible to-near-infrared spectral range, useful in quantum networks. Heralded single photons at 683 nm were translated to 659 nm with an efficiency of $28.6 \pm 2.2$ percent. Second-order correlation measurements on the 683-nm and 659-nm fields yielded $g^{(2)}_{683}(0) = 0.21 \pm 0.02$ and $g^{(2)}_{659}(0) = 0.19 \pm 0.05$ respectively, showing the nonclassical nature of both fields.Comment: 5 pages, 3 figure