5,658 research outputs found
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
The physical nature of interplanetary dust as inferred by particles collected at 35 km
Particles were collected at an altitude of 35 km by two flights of a volume sampling micrometeorite collector. The collection scheme is very sensitive and is capable of collecting a significant number of particles. Many of the particles collected have chemical compositions similar to solar or to iron meteorites. Morphology of collected particles indicates that both true micrometeorites and ablation products were collected
The initial conditions of the universe: how much isocurvature is allowed?
We investigate the constraints imposed by the current data on correlated
mixtures of adiabatic and non-adiabatic primordial perturbations. We discover
subtle flat directions in parameter space that tolerate large (~60%)
contributions of non-adiabatic fluctuations. In particular, larger values of
the baryon density and a spectral tilt are allowed. The cancellations in the
degenerate directions are explored and the role of priors elucidated.Comment: 4 pages, 4 figures. Submitted to PR
Constraints on isocurvature models from the WMAP first-year data
We investigate the constraints imposed by the first-year WMAP CMB data
extended to higher multipole by data from ACBAR, BOOMERANG, CBI and the VSA and
by the LSS data from the 2dF galaxy redshift survey on the possible amplitude
of primordial isocurvature modes. A flat universe with CDM and Lambda is
assumed, and the baryon, CDM (CI), and neutrino density (NID) and velocity
(NIV) isocurvature modes are considered. Constraints on the allowed
isocurvature contributions are established from the data for various
combinations of the adiabatic mode and one, two, and three isocurvature modes,
with intermode cross-correlations allowed. Since baryon and CDM isocurvature
are observationally virtually indistinguishable, these modes are not considered
separately. We find that when just a single isocurvature mode is added, the
present data allows an isocurvature fraction as large as 13+-6, 7+-4, and 13+-7
percent for adiabatic plus the CI, NID, and NIV modes, respectively. When two
isocurvature modes plus the adiabatic mode and cross-correlations are allowed,
these percentages rise to 47+-16, 34+-12, and 44+-12 for the combinations
CI+NID, CI+NIV, and NID+NIV, respectively. Finally, when all three isocurvature
modes and cross-correlations are allowed, the admissible isocurvature fraction
rises to 57+-9 per cent. The sensitivity of the results to the choice of prior
probability distribution is examined.Comment: 20 pages, 24 figures. Submitted to PR
Size-dependent Surface States on Strained Cobalt Nanoislands on Cu(111)
Low-temperature scanning tunneling spectroscopy over Co nanoislands on
Cu(111) showed that the surface states of the islands vary with their size.
Occupied states exhibit a sizeable downward energy shift as the island size
decreases. The position of the occupied states also significantly changes
across the islands. Atomic-scale simulations and ab inito calculations
demonstrate that the driving force for the observed shift is related to
size-dependent mesoscopic relaxations in the nanoislands.Comment: 4 pages, 4 figure
Laparoscopic versus open resection for appendix carcinoid
Background: Since an increasing number of appendectomies are performed via laparoscopy, it is crucial to determine the impact of this approach on appendix carcinoid (AC) outcome. The goal of this study was to compare results of laparoscopic (LAP) versus open (OP) appendectomy for AC according to intend to treat approach. Methods: A retrospective review (1991-2003) identified 39 patients (median age, 36 years; range, 12-83) treated by laparoscopy (LAP) or laparotomy (OP) for AC in a single institution. Follow-up was complete for all patients (median, 67 months; range, 4-132). Results: Most cases had associated acute appendicitis (64%). Median carcinoid size was 1.1 cm (range, 0.3-5) and 0.4 cm (range, 0.2-3) in the LAP and OP groups, respectively. LAP and OP were performed in 21 (54%) and 18 (46%) patients, respectively. Surgical margins were positive in two patients in the LAP group and one patient in the OP group (p = 0.6). Right colectomies were performed for AC >2 cm in five patients after LAP and in four patients after OP (p = 0.9). Actuarial 5-year survival rates were 100 and 94% in the LAP and OP groups, respectively (p = 0.2). Two patients died in the OP group, one due to metastatic carcinoid and the other due to metachronous colorectal cancer. Synchronous or metachronous colorectal carcinomas developed in six patients (15%). Conclusion: Laparoscopic appendectomy is a safe procedure for AC, with carcinologic and long-term results similar to those of conventional appendectomy. Thus, pre- or per-operative suspicion of AC is not a contraindication to LAP. Prognosis of AC appears more dependent on carcinoid malignant potential or associated tumors. Risk for developing colorectal adenocarcinoma is high in AC patients and warrants follow-up of all patients with colonoscopic screenin
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