Radio-frequency impedance measurements using a tunnel-diode oscillator (TDO) technique

A resonant method based on a tunnel-diode oscillator (TDO) for precision measurements of relative impedance changes in materials, is described. The system consists of an effective self-resonant LC-tank circuit driven by a forward-biased tunnel diode operating in its negative resistance region. Samples under investigation are placed in the core of an inductive coil and impedance changes are determined directly from the measured shift in resonance frequency. A customized low temperature insert is used to integrate this experiment with a commercial Model 6000 Physical Property Measurement System (Quantum Design). Test measurements on a manganese-based perovskite sample exhibiting colossal magneto-resistance (CMR) indicate that this method is well suited to study the magneto-impedance in these materials.Comment: Rev. Sci. Instrum. (in press), PDF file, 6 pages, 2-column, embedded figure

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

Economic Conditions, Deterrence and Juvenile Crime: Evidence from Micro Data

This is the first paper to test the economic model of crime for juveniles using micro data. It uses a nationally representative sample of 16,478 high school children surveyed in 1995. The sample includes not only detailed information on offenses, but also data on personal, family and neighborhood characteristics as well as deterrence measures. We analyze the determinants of selling drugs, committing assault, robbery, burglary and theft, separately for males and females. We find that an increase in violent crime arrests reduces the probability of selling drugs and assaulting someone for males, and reduces the probability of selling drugs and stealing for females. An increase in local unemployment increases the propensity to commit crimes, as does local poverty. Similarly, family poverty increases the probability to commit robbery, burglary and theft for males, and assault and burglary for females. Local characteristics are more important for females than males. The results also indicate that family supervision has an impact on delinquent behavior. These results show that juveniles do respond to incentives and sanctions as predicted by economic theory. Employment opportunities, increased family income and more strict deterrence are effective tools to reduce juvenile crime.

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: 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: 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: 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: 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)

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