The feasibility of making short-term migration estimates

Short-term migration, that is stays of less than 12 months, has received particular attention recently from both national and local level users of population statistics. This interest is part of the wider interest shown in increasing levels of long-term migration statistics in recent years. This article is an initial assessment by ONS of the potential to produce short-term migration estimates for England and Wales, and the challenges faced in doing so. Central to these challenges is the question of how short-term migration should be defined. In addition, illustrative estimates of short-term migration based on the International Passenger Survey (IPS) are provided. These illustrative estimates, along with associated standard errors, are provided at both national and regional levels using a number of definitional bases.     

ASYMPTOTIC NORMALITY OF SOME ESTIMATORS IN A FIXED-DESIGN SEMIPARAMETRIC REGRESSION MODEL WITH LINEAR TIME SERIES ERRORS

Consider a semiparametric regression model with linear time series errors Yk = x'kβ g(tk) εk, 1 < k < n, where Yk's are responses, xk = (xk1,xk2,..... ,xkp)' and tk ∈T ∪R are fixed design points, β= (β1, β2, ....., βp)' is an unknown parameter vector, g(.) is an unknown bounded real-valued function defined on a compact subset T of the real line R, and εk is a linear process given by εk = ∑j=0∞j(?)ek-j,(?)= 1, where , are i.i.d. random variables. In this paper we establish the asymptotic normality of the least squares estimator of β, a smooth estimator of g(.), and estimators of the autocovariance and autocorrelation functions of the linear process εk.     

Estimates of true birth order for Scotland, 1945-1999

Over the last three decades fertility in Scotland, as measured by the total fertility rate (TFR), has moved from being higher than in England and Wales, to being lower. The annual number of births in Scotland has declined so that in the mid-1990s low fertility became the main driver of the overall population decline that Scotland has been experiencing since 1974. Analysis of fertility by birth order is instrumental in gaining an understanding of past and future fertility trends. Until the rise in births outside marriage in the 1980s data from registration could be used as a proxy for true birth order. However, because birth order is not collected for births outside marriage true birth order now has to be estimated. This article presents the first official estimates of true birth order for Scotland. The construction of these estimates based on a modified version of the method used for England and Wales is discussed. This article also presents analysis relating births by true birth order estimate to the population of women by parity on a cohort basis, and makes comparisons with England and Wales.     

Small area population estimates project: data quality of administrative datasets

The Office for National Statistics (ONS) has set up a project to investigate the feasibility of producing postcensal small area population estimates on a nationally consistent basis for England and Wales. Research has taken place to identify datasets that could potentially be used within a method to produce small area population estimates. Following an evaluation of a number of different administrative datasets, the most suitable have been short-listed for further consideration. This article presents the findings of the evaluation, based on 2001 data, and summarises the characteristics of these short-listed data sources. This article does not cover the methods that are being evaluated as part of the feasibility assessment.     

Family building intentions in England and Wales: trends,outcomes and interpretations

This article presents and analyses women's childbearing intentions collected in the General Household Survey (GHS). Data from the 21 surveys from 1979 to 2001 show that over that period there has been a fall in women's intended numbers of births. However the latest data (from the 1998, 2000 and 2001 surveys) show that the average number of children intended is still around two, somewhat higher than the average number of children current fertility rates suggest women will have. The questions of whether this difference can be interpreted as possible unmet need for children, whether past intentions have been good predictors of fertility, and how current intentions may be used to inform projections assumptions are discussed. In relation to the last question, fertility intentions by ethnic group are also presented.     

Which authorities are alike?

This article describes the first results from the recent revision to The ONS classification of local and health authorities of Great Britain to allow for boundary changes. For each local and health authority of Great Britain as at April 1999 it presents 'most similar' authorities as measured by a selection of 37 socioeconomic and demographic variables from the 1991 Census. These results will assist local and health authorities in identifying other appropriate authorities for comparative studies. A second article, to be published in Population Trends 99, will present the results of the analysis to identify groups of authorities in a hierarchy of new Clusters, Groups and Families for the revised classification.     

交错群A_p的数量刻画(英文)

证明了若p≥ 5且p与p - 2 均为素数 ,则交错群Ap 可用元的阶刻画     

Evidence for ubiquitous strong electron-phonon coupling in high-temperature superconductors

Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron-phonon coupling in the electron dynamics of the high-transition-temperature superconductors has driven an intensive search for an alternative mechanism. A coupling of an electron with a phonon would result in an abrupt change of its velocity and scattering rate near the phonon energy. Here we use angle-resolved photoemission spectroscopy to probe electron dynamics-velocity and scattering rate-for three different families of copper oxide superconductors. We see in all of these materials an abrupt change of electron velocity at 50-80 meV, which we cannot explain by any known process other than to invoke coupling with the phonons associated with the movement of the oxygen atoms. This suggests that electron-phonon coupling strongly influences the electron dynamics in the high-temperature superconductors, and must therefore be included in any microscopic theory of superconductivity.     

Normal faulting in central Tibet since at least 13.5 Myr ago

Tectonic models for the evolution of the Tibetan plateau interpret observed east-west thinning of the upper crust to be the result of either increased potential energy of elevated crust or geodynamic processes that may be unrelated to plateau formation. A key piece of information needed to evaluate these models is the timing of deformation within the plateau. The onset of normal faulting has been estimated to have commenced in southern Tibet between about 14 Myr ago and about 8 Myr ago and, in central Tibet, about 4 Myr ago. Here, however, we report a minimum age of approximately 13.5 Myr for the onset of graben formation in central Tibet, based on mineralization ages determined with Rb-Sr and 40Ar-39Ar data that post-date a major graben-bounding normal fault. These data, along with evidence for prolonged activity of normal faulting in this and other Tibetan grabens, support models that relate normal faulting to processes occurring beneath the plateau. Thinning of the upper crust is most plausibly the result of potential-energy increases resulting from spatially and temporally heterogeneous changes in thermal structure and density distribution within the crust and upper mantle beneath Tibet. This is supported by recent geophysical and geological data, which indicate that spatial heterogeneity exists in both the Tibetan crust and lithospheric mantle.