Simple models of small world networks with directed links

We investigate the effect of directed short and long range connections in a simple model of small world network. Our model is such that we can determine many quantities of interest by an exact analytical method. We calculate the function $V(T)$, defined as the number of sites affected up to time $T$ when a naive spreading process starts in the network. As opposed to shortcuts, the presence of un-favorable bonds has a negative effect on this quantity. Hence the spreading process may not be able to affect all the network. We define and calculate a quantity named the average size of accessible world in our model. The interplay of shortcuts, and un-favorable bonds on the small world properties is studied.Comment: 15 pages, 9 figures, published versio

Retirement return migration from Sweden

This study deals with return migration among immigrants in Sweden who are between 51 and 80 years old. An important question regards the impact of retirement on return migration. Some circumstances connected to the withdrawal from the labour market suggest an increased propensity to return, such as the transition from a wage income to a pension, which weakens the link between place of residence and income. In addition, patterns of return migration at the end of working life may indicate whether or not temporary migration is a planned strategy. It is found that when reaching the age of 65, the legal retirement age in Sweden, the probability of return migration increases, in particular for men. The effect of retirement is immediate; the probability of return migration declines again beyond the age of 65, indicating a conscious plan to return to the home country when the labour market career is over. Furthermore, immigrants who receive early retirement compensation have a considerably higher probability of return migration compared to those who are not retired. These clear "retirement effects" show that return migration can be an important ingredient in the welfare optimization strategies of migrants. When it comes to income selectivity, the analysis shows that there is a positive selection, something that is expected when migrants are target savers with a temporary migration strategy