Internal Migration and Regional Population Dynamics in Europe: Norway Case Study

This paper reports on internal migration and regional population dynamics in Norway. It examines internal migration patterns and trends in two years, 1984 and 1994, and compares them. Norway's population maintains relatively high population growth by European standards, fuelled by continuing natural increase and net migration from outside the country. About half of Norway's municipalities lost population in aggregate over the 1984 to 1994. These municipalities are concentrated in the Centre-North and interior of southern Norway. There is evidence that communities with the lowest densities and least centrality are losing population through internal migration. Although the direction of migration is towards denser and more central places, this is a product mainly of the migration of young people when the migration streams are broken down by age, the resulting tales show that the largest urban areas are experiencing net losses from middle age and upwards. There is little direct evidence of net positive migration flows to rural remote areas for the population as a whole. Migration flows out of the Oslo region are to other municipalities within commuting range. This deconcentration should therefore be identified as extended suburanisation rather than counter-urbanisation. Throughout the current report the role of life course stage in influencing the direction of migration has been stressed. Most often the overall pattern of population shifts conceal very different flow structures for family migrants, young adults, older workers, retirees and the elderly. In this respect internal migration dynamics in Norway strongly resemble those in other West European countries. Economic factors have an important influence on migration patterns. Municipalities with an economic concentration in service industries attract internal migrants while those specialised in primary industry suffer migration outflows consequent on the decline of or productivity improvements in their economic activities. There is a strong gradient of increasing net outflows with increasing levels of unemployment

Double-layer shocks in a magnetized quantum plasma

The formation of small but finite amplitude electrostatic shocks in the propagation of quantum ion-acoustic waves (QIAWs) obliquely to an external magnetic field is reported in a quantum electron-positron-ion (e-p-i) plasma. Such shocks are seen to have double-layer (DL) structures composed of the compressive and accompanying rarefactive slow-wave fronts. Existence of such DL shocks depends critically on the quantum coupling parameter $H$ associated with the Bohm potential and the positron to electron density ratio $\delta$. The profiles may, however, steepen initially and reach a steady state with a number of solitary waves in front of the shocks. Such novel DL shocks could be a good candidate for particle acceleration in intense laser-solid density plasma interaction experiments as well as in compact astrophysical objects, e.g., magnetized white dwarfs.Comment: 4 pages, 1 figure (to appear in Physical Review E

Internal Migration and Regional Population Dynamics in Europe: Sweden Case Study

This paper describes the structure of internal migration and population change in Sweden in recent decades, focussing on the years 1988 and 1998 to capture change in the last decade. Up to the 1970s and again in the early 1990s natural increase play an important role in regional population dynamics. In the late 1990s growing international migration, decreasing fertility and strong net internal migration into large cities increased the importance of migration at both national and local levels. In 1988 migration flows contributed to a pattern of relatively even deconcentration of population. Urban centres and surrounding communities experienced mixed patterns of growth. The pattern observed in 1998 was entirely different. It showed a strong movement up the urban hierarchy. Rural and remote areas, especially those in Norrland, depopulated. In 1998 migrants moved from low-density areas to high-density. High density areas had much higher population gains than low density over the 1988–1998 period. There is a difference in migration pattern between the north of the country, which mostly loses population and the central and southern parts, which mostly gain people. The pattern of migration of the Swedish population is, to large extent, related to the level of unemployment. Low unemployment areas attract migrants; high unemployment areas lose them. However, the level of unemployment cannot be considered in isolation, because the level of unemployment is correlated with the level of urbanisation and with type of regional economy. Areas with an educated population have a very strong attraction for migrants. A high level of education is indispensable for high level services, including tertiary education, and for high technology enterprises, which attract migrants. Young people migrate to metropolitan areas and university towns out of the other types of municipality. Medium sized municipalities attract families. Outflows from industrial regions and Inner Norrland municipalities are visible in all age groups. Metropolitan areas are gaining popularity among families. The elderly population migrates to university and medium size municipalities

Spectra of Unsteady Wind Models of Gamma-Ray Bursts

We calculate the spectra expected from unsteady relativistic wind models of gamma-ray bursts, suitable for events of arbitrary duration. The spectral energy distribution of the burst is calculated over photon energies spanning from eV to TeV, for a range of event durations and variability timescales. The relative strength of the emission at different wavelengths can provide valuable information on the particle acceleration, radiation mechanisms and the possible types of models.Comment: 10 pages, 2 postscript figures included, uses aaspp4.sty. Accepted for publication in the Astrophysical Journal Letters. Also available at http://www.astro.psu.edu/users/hara/Preprints/xxx_sub.p

A Model for the Moving `Wisps' in the Crab Nebula

I propose that the moving `wisps' near the center of the Crab Nebula result from nonlinear Kelvin-Helmholtz instabilities in the equatorial plane of the shocked pulsar wind. Recent observations suggest that the wisps trace out circular wavefronts in this plane, expanding radially at speeds approximately less than c/3. Instabilities could develop if there is sufficient velocity shear between a faster-moving equatorial zone and a slower moving shocked pulsar wind at higher latitudes. The development of shear could be related to the existence of a neutral sheet -- with weak magnetic field -- in the equatorial zone, and could also be related to a recent suggestion by Begelman that the magnetic field in the Crab pulsar wind is much stronger than had been thought. I show that plausible conditions could lead to the growth of instabilities at the radii and speeds observed, and that their nonlinear development could lead to the appearance of sharp wisplike features.Comment: 7 pages; 3 postscript figures; LaTex, uses emulateapj.sty; to Appear in the Astrophysical Journal, Feb. 20, 1999, Vol. 51

Spectropolarimetric observations of the Ca II 8498 A and 8542 A lines in the quiet Sun

The Ca II infrared triplet is one of the few magnetically sensitive chromospheric lines available for ground-based observations. We present spectropolarimetric observations of the 8498 A and 8542 A lines in a quiet Sun region near a decaying active region and compare the results with a simulation of the lines in a high plasma-beta regime. Cluster analysis of Stokes V profile pairs shows that the two lines, despite arguably being formed fairly close, often do not have similar shapes. In the network, the local magnetic topology is more important in determining the shapes of the Stokes V profiles than the phase of the wave, contrary to what our simulations show. We also find that Stokes V asymmetries are very common in the network, and the histograms of the observed amplitude and area asymmetries differ significantly from the simulation. Both the network and internetwork show oscillatory behavior in the Ca II lines. It is stronger in the network, where shocking waves, similar to those in the high-beta simulation, are seen and large self-reversals in the intensity profiles are common.Comment: 23 pages, 17 figures, accepted to ApJ some figures are low-res, for high-res email [email protected]

Imprint of Inhomogeneous Reionization on the Power Spectrum of Galaxy Surveys at High Redshifts

We consider the effects of inhomogeneous reionization on the distribution of galaxies at high redshifts. Modulation of the formation process of the ionizing sources by large scale density modes makes reionization inhomogeneous and introduces a spread to the reionization times of different regions with the same size. After sources photo-ionize and heat these regions to a temperature \ga 10^4K at different times, their temperatures evolve as the ionized intergalactic medium (IGM) expands. The varying IGM temperature makes the minimum mass of galaxies spatially non-uniform with a fluctuation amplitude that increases towards small scales. These scale-dependent fluctuations modify the shape of the power spectrum of low-mass galaxies at high redshifts in a way that depends on the history of reionization. The resulting distortion of the primordial power spectrum is significantly larger than changes associated with uncertainties in the inflationary parameters, such as the spectral index of the scalar power spectrum or the running of the spectral index. Future surveys of high-redshift galaxies will offer a new probe of the thermal history of the IGM but might have a more limited scope in constraining inflation.Comment: 8 pages, 5 figures, replaced to match version accepted by Ap

Interventions for Pre-School Children with Co-Occurring Phonological Speech Sound Disorder and Expressive Language Difficulties: A Scoping Review Protocol

Background: Pre-school children with co-occurring phonological speech sound disorder and expressive language difficulties are more likely to have ongoing communication and literacy needs compared to children with these difficulties in isolation. However, to date there has been no systematic or scoping review of the literature specific to interventions for this frequently seen and high-risk group. // Aims: The objective of this paper is to provide a rigorous and detailed protocol for a scoping review of interventions, which target both phonological speech sound disorder and expressive language difficulties in pre-school children with primary speech, language and communication needs. The protocol includes details on the development of a search strategy, as well as the trial of an extraction tool. // Methods/Design: Included studies must aim to concurrently improve both speech production and expressive language. Children within included studies must be aged between 2:0 and 5:11 years and have communication needs with no known cause. In accordance with the Joanna Briggs institute scoping review methods guidelines, an initial search of the Ovid Emcare and Ovid Medline databases was conducted. Following this a final search strategy for these databases were produced. A draft extraction form was developed by the first author; this was then trialed by two authors on four articles each. // Discussion: Following the systematic development of an initial search strategy and extraction form, a scoping review of this topic can take place. The development of a rigorous scoping review protocol is essential in enhancing the transparency and reliability of the subsequent review. A pre-developed search strategy and trialing of an extraction form is a fundamental part of this process

Double Lobed Radio Quasars from the Sloan Digital Sky Survey

We have combined a sample of 44984 quasars, selected from the Sloan Digital Sky Survey (SDSS) Data Release 3, with the FIRST radio survey. Using a novel technique where the optical quasar position is matched to the complete radio environment within 450", we are able to characterize the radio morphological make-up of what is essentially an optically selected quasar sample, regardless of whether the quasar (nucleus) itself has been detected in the radio. About 10% of the quasar population have radio cores brighter than 0.75 mJy at 1.4 GHz, and 1.7% have double lobed FR2-like radio morphologies. About 75% of the FR2 sources have a radio core (> 0.75 mJy). A significant fraction (~40%) of the FR2 quasars are bent by more than 10 degrees, indicating either interactions of the radio plasma with the ICM or IGM. We found no evidence for correlations with redshift among our FR2 quasars: radio lobe flux densities and radio source diameters of the quasars have similar distributions at low (mean 0.77) and high (mean 2.09) redshifts. Using a smaller high reliability FR2 sample of 422 quasars and two comparison samples of radio-quiet and non-FR2 radio-loud quasars, matched in their redshift distributions, we constructed composite optical spectra from the SDSS spectroscopic data. Based on these spectra we can conclude that the FR2 quasars have stronger high-ionization emission lines compared to both the radio quiet and non-FR2 radio loud sources. This is consistent with the notion that the emission lines are brightened by ongoing shock ionization of ambient gas in the quasar host as the radio source expands.Comment: 20 pages, 10 figures - some of which have been reduced in quality / size. Accepted for publication in the Astronomical Journa