8,769 research outputs found
Internal Migration and Regional Population Dynamics in Europe: United Kingdom Case Study
This case study examines recent population change patterns and internal migration activity in the United Kingdom. A wealth of knowledge about population dynamics in Britain is revealed. The spatial patterns of population change and net migration are intricate mosaics of gains and losses. Gains and losses in population were principally determined by net internal migration. The decade long population change patterns and one year long migration patterns were in close
agreement. This was surprising in view of temporal instability in population change and migration patterns. The dominant spatial pattern was one of deconcentration from the cores of city regions to hinterlands for both the largest metropolises and also their subsidiary partner cities. There were also signs of loss in population and migrants in declining resource regions(former mining areas, fishing ports) and gains in new resource frontiers - particularly in northeast Scotland reflecting the vigorous development of onshore facilities for the offshore oil and gas fields of the North Sea. The pattern of overall population and migrant redistribution was predominantly that of the middle labour force/family ages reinforced at much lower mobility levels but with sharper patterns of redistribution by the pre-retirement and retirement ages. People in the young adult ages in contrast redistributed to different destinations, showing a unique shift to the dense neighbourhoods of big cities. With respect to the urban system, there was significant redistribution both downward and outward. Downward redistribution meant shifts from large metropolitan cities to medium and small sized freestanding cities. Outward redistribution meant shifts to the outer commuting rings around cities, often deep into the countryside, This was not a return to the rural idyll, merely the expansion of the daily urban systems to cover most of lowland Britain. Strong preferences for low density living were revealed by shifts towards districts in Rural Areas and by net flows to low density wards and
sectors. Similar strong shifts out of areas of above average into below average unemployment were detected, though both relationships with density and unemployment were either not
present or weak for young adults. Some ambiguity was revealed in the fortunes of Inner London areas. Migration data from the 1991 Census showed intense outward movement.
Downward population shifts were on a lesser scale because of the compensating effects of higher than average natural increase and high immigration. However, a re-analysis of 1991 population by ONS led to a substantial upward revision of London borough populations, and so places doubt on the size of outward shift of population through internal migration
Internal Migration and Regional Population Dynamics in Europe: German Case Study
Report prepared for the Council of Europe (Directorate of Social and Economic Affairs, Population and Migration Division) and for European Commission (Directorate General V, Employment, Industrial Relations and Social Affairs, Unit E1, Analysis and Research on the Social Situation)
This paper reports on internal migration and regional population dynamics and to a lesser extend on international migration in Germany. It examines internal migration patterns and trends in two years, 1984, 1989 and 1993, and compares them. Germany has a particularly sophisticated population system with a large number of population categories behaving in a very different way. The indigenous population shows a pattern of urban deconcentration typical for affluent West-European countries, both in the forms of suburbanisation and counterurbanisation. All other groups of migrants, those coming from former East Germany, those of German origin coming from outside Germany (Aussiedler) and other international migrants, show a pattern of strong concentration in urban centres. As far as migrations from East to West Germany is concerned the pattern is changing, as the number of migrants declines rapidly. Also in East Germany itself there is a marked shift. The pattern of rapid concentration of population due mainly to rural to urban migration is moving, for the time being, to weak and fragmented deconcentration. This process will speed up with the economic development of Eastern Länder.
Medium density areas gain people, high and low density areas lose people. The relationship between net migration on the one hand and population density on the other was strongly negative for low density areas and for the less populated areas. The gainers were areas with a medium density of population.
The age of migrants has a profound impact on their behaviour. There are important variations in redistribution of population by life course stage. The dominant urban deconcentration was most characteristic of middle working and family ages and the pre-retirement and retirement ages. People in the young adult ages migrated in different directions, showing a unique shift to some dense neighbourhoods in big cities, those close to higher education institutions. Unemployment influences migration profoundly. People move between areas of differing unemployment in ways predicted by classical economic equilibrium theory, leaving areas of high unemployment and going to areas of lower unemployment.
German population dynamics depends on three factors: natural increase (persistently negative), internal migration and international migration. International migration is the only factor which maintains the size of population and even allows for a moderate growth. There is no direct threat that the population inhabiting German territory, will decline in the near future, but this may happen to the German population
Spectral Properties of Blast Wave Models of Gamma-Ray Burst Sources
We calculate the spectrum of blast wave models of gamma-ray burst sources,
for various assumptions about the magnetic field density and the relativistic
particle acceleration efficiency. For a range of physically plausible models we
find that the radiation efficiency is high, and leads to nonthermal spectra
with breaks at various energies comparable to those observed in the gamma-ray
range. Radiation is also predicted at other wavebands, in particular at X-ray,
optical/UV and GeV/TeV energies. We discuss the spectra as a function of
duration for three basic types of models, and for cosmological, halo and
galactic disk distances. We also evaluate the gamma-ray fluences and the
spectral characteristics for a range of external densities. Impulsive burst
models at cosmological distances can satisfy the conventional X-ray paucity
constraint S_x/S_\gamma \siml few percent over a wide range of durations, but
galactic models can do so only for bursts shorter than a few seconds, unless
additional assumptions are made. The emissivity is generally larger for bursts
in a denser external environment, with the efficiency increasing up to the
point where all the energy input is radiated away.Comment: 24 pages of Tex, plus 17 figures uuencoded tar-compressed postscript
file
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
Internal Migration and Regional Population Dynamics in Europe: France Case Study
The paper examines the patterns of internal migration and population change in France over the recent decades at departément and commune scales. Regional population change is controlled by both natural increase and internal migration. There are two differing patterns of natural increase: north and east France has higher natural increase and south and east has lower. The geographic pattern of internal migration has changed substantially over the last 50 years, most dramatically in the Île-de-France, which showed the highest gains between 1954 and 1962 but the highest losses between 1975 and 1982. Urban growth, which was strong in the 1950s and 1960s, reversed in the 1970s favouring small towns but recovered slightly in the last 20 years.
Migration gains and losses show a quite complicated pattern of depopulation of city centres combined with slow suburbanisation and advanced periurbanisation. Periurbanisation is evident in Paris region and in nearly all large urban agglomerations. Most other cities show suburbanisation or periurbanisation at various stages of development.
Out-migration shows a clear division of the country into a northern part with higher rates, and a central and southern part of the country with lower out-migration. This simple pattern is modified by higher out-migration from some cities such as Lyon or Clermont-Ferrand and from isolated rural communes scattered all over the country. Out-migration also has a regional dimension: there are shifts towards more attractive areas, in particular Alpine region and Mediterranean and Atlantic coasts.
Analysis of migration between size bands of rural and urban units shows a significant deconcentration process, and a similar pattern characterises migration between population density bands. The general movement is down the urban/density band hierarchy, from higher to lower urban/density bands. Deep rural areas are not attractive and excluded from the process of counterurbanisation. In addition, unemployment was found to have a strong and very efficient impact on migration behaviour.
Analysis for 1990-1999 leads to slight modification of this picture: a slow recovery of central parts of the largest urban agglomerations and less differentiated patterns than in the 1980s. Deconcentration of the French population continues but is less powerful
Internal Migration and Regional Population Dynamics in Europe: Denmark Case Study
This report analyses the patterns of internal migration and population change across the communes of Denmark as part of a multi-country study of regional population dynamics in Europe, comparing the 1980s and 1990s. Section 2 of the report reviews the recent history of internal migration and regional/local population change in Denmark. Section 3 documents data sources and structure. Section 4 provides a detailed cartographic analysis of the patterns of in-migration, out-migration and net-migration at commune level for 1985 and 1998 (the years selected for study), while section 5 reviews population change between 1985 and 1998. Overall net migration shifts have decreased between the two years. The spatial pattern combines losses from peripheral regions (western Jutland, Bornholm) and Copehagen suburbs with gains to commuting belts centred on Copenhagen and the other large towns. As many other high income European countries, there is a profound contrast between the migration behaviour of young people and other adults (families, older workers and the retired). Young people move strongly towards the centre of the capital region and other large towns, while the other groups deconcentrate. Section 6 analyses the relationships between net migration/population change and the settlement system, to calibrate more precisely the patterns observed on the maps, while sections 7 and 8 look at the relationships between internal migration and economic/functional classifications of the communes. The former relationships are stronger than the latter, but are not as well clearly structured with respect to the urban hierarchy or population density as in many other countries studied. Denmark has reached a system state beyond simple counterurbanisation to be characterised by periurbanisation in the Copenhagen region, reurbanisation in Copenhagen itself and moderate outflows from rural regions
Internal Migration and Regional Population Dynamics in Europe: Portugal Case Study
Report prepared for the Council of Europe (Directorate of Social and Economic Affairs, Population and Migration Division) and for European Commission (Directorate General V, Employment, Industrial Relations and Social Affairs, Unit E1, Analysis and Research on the Social Situation).
This paper reports on internal migration and regional population dynamics in Portugal. It examines internal migration patterns and trends in two years, 1981 and 1991, and compares them. Portugal is a country that has reached a population plateau and is currently experiencing very little overall population growth. In 1981 its population was 9.83 millions, only 9.87 millions in 1991 and 9.96 millions in 1997. During the 1980s natural increase steadily diminished and in the 1990s it has virtually ceased. International migration was predominantly negative in balance during the period between the mid 1980s and early 1990s, but has moved into small positive gains in the last few years. When population changes for the 1981-91 period are examined, the picture is broadly of gains in the major urban-centred regions of Norte and Lisboa Vale Tejo, and in the resort industry region of the Algarve. In the more peripheral regions, population decreases occurred, that is in the Centro, Alentejo and Açores regions with Madeira being roughly in balance. Natural increase was strong in the Norte and island regions and compensated for net out-migration, while elsewhere it was weak. All Portuguese NUTS 2 regions except the Algarve lost through migration, with emigration dominating any counter-flows due to internal migration.
However, the strong influence of internal migration is apparent when the components of population change at concelhos scale are analysed. The largest cities, Lisboa and Porto, lose population in the 1981-91 period, particularly the capital, and part of the population losses represent migration to surrounding concelhos in the Outer parts of the city regions. Most of the rest of Grande Porto outside of the main city gains population through migration. Around Lisboa these suburban migration gains were experienced by the margins of Lisboa itself, the northern suburbs along the north bank of the Tagus and in a majority of the concelhos of Península Setúbal across the Tagus estuary from Lisboa, namely the southern suburbs linked to the city by two major road bridges.
The Censuses of 1981 and 1991, which count migrants in the circa 15-month period before the census date (14½ and 15½ months in the two censuses), provide a picture of how internal migration affects people in different life stages. The all ages pattern of migration in 1979-81 is one of greatest losses from interior and eastern regions (NUTS 3 scale), lesser losses from remoter coastal regions and gains to the urban regions centred on Porto, Lisboa and the Algarve resorts. However, the centres of the Porto and Lisboa regions lose migrants, confirming the earlier interpretation of the components of population change. The situation in 1989-91 was similar but there were fewer regions with great migration losses, more regions with moderate losses and gains around the main urban nodes and the southern tourist coast. This general pattern of redistribution characterises the childhood and family ages (0-14, 25-44) and is intensified in terms of losses from the large cities and suburban gains in the 45-64 age group. Young persons, however, behave differently. In 1979-81 most of the regions of the country lost internal migrants in the 15-24 age group, while Lisboa, Porto and the Algarve experienced substantial migration gains. So, while the family ages showed a de-concentration pattern, the ages at which young adults start independent life careers showed centralising tendencies. The spatial pattern was broadly similar in 1989-91 but more interior regions posted migration gains. The retirement ages, 65 to 74, showed similar centralisation for the female population but not for the male. This age group was the only one that exhibited strong gender differences in the pattern of migration and considerable changes between 1979-81 and 1989-91. Whereas in the former period, the pattern was very much one of interior loss and coastal and urban region gain, in 1989-91, losses from the interior were relatively lower and moderate gains more widespread. At the oldest ages of 75 years or more the strong pattern of interior loss and coastal gain reasserted itself.
Portuguese population dynamics thus exhibit some rural depopulation (mainly of the young and the very old), some urbanisation (migration to more densely settled regions around the biggest cities), some suburbanisation (de-concentration within the largest urban regions) and some regional flows to resource exploiting regions (sun and sea in the resort coast of the Algarve). Population gains in the 1981-91 decade also occurred in several coastal and interior small towns and medium-sized urban centres outside of Lisboa and Porto. This reveals that urbanisation was not just a metropolitan phenomenon but was a widespread process. Note that when considering whether the Portuguese population is centralising or decentralising, attention must be paid to the scale of migration observed. So, for example, population may be moving into the metropolitan regions of Lisboa and Porto and therefore centralising, but within those regions the population may be shifting from city to suburbs and to outer parts of the city region, and therefore decentralising. This nested system of flows may be obscured if attention is focused exclusively on total net migration
Internal Migration and Regional Population Dynamics in Europe: Romanian Case Study
The report analyses population migration and change in Romania over the period 1984-1994. The analysis of population change is conducted for 2948 communes and towns, the finest administrative division for which population data are available. The lack of migration data on the level of communes and towns makes in-depth analysis of the migration for small spatial units impossible. For that reason analysis of the patterns of migration is conducted for 40 Judete (also referred to as counties or regions) and the capital city of Bucharest, i.e. 41 units altogether.
Council of Europe Publishing,
F-67075 Strasbourg - Cedex,
France
Internal Migration and Regional Population Dynamics in Europe: Switzerland Case Study
This paper reports on internal migration and regional population dynamics in Switzerland. It examines briefly the main population trends in the last century and then turns to more detailed examination of internal migration patterns and trends in three years, 1984, 1994 and 1996 and compares them. First, inter-cantonal migration is investigated in the context of the life course. On the communal level population change patterns and underlying in-, out- and net migration are examined. An attempt is made to link migration with such variables as population density, level of unemployment, prevailing language and with a functional classification of the urban system. The methodology used is the same as in a number of other studies, making the results as comparable as possible with the results of other studies of migration in European states (Rees and Kupiszewski 1999)
The Radiative Feedback of the First Cosmological Objects
In hierarchical models of structure formation, an early cosmic UV background
(UVB) is produced by the small (T_vir < 10^4 K) halos that collapse before
reionization. The UVB at energies below 13.6eV suppresses the formation of
stars or black holes inside small halos, by photo-dissociating their only
cooling agent, molecular H2. We self-consistently compute the buildup of the
early UVB in Press-Schechter models, coupled with H2 photo-dissociation both in
the intergalactic medium (IGM), and inside virialized halos. We find that the
intergalactic H2 has a negligible effect on the UVB, both because its initial
optical depth is small (tau<0.1), and because it is photo-dissociated at an
early stage. If the UV sources in the first collapsed halos are stars, then
their UV flux suppresses further star-formation inside small halos. This
results in a pause in the buildup of the UVB, and reionization is delayed until
larger halos (T_vir> 10^4 K) collapse. If the small halos host mini-quasars
with hard spectra extending to approximately 1 keV, then their X-rays balance
the effects of the UVB, the negative feedback does not occur, and reionization
can be caused by the small halos.Comment: 16 pages, 16 figures included, uses emulateapj.sty. Submitted to Ap
- …