2,215 research outputs found

    Quantization of edge currents for continuous magnetic operators

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    For a magnetic Hamiltonian on a half-plane given as the sum of the Landau operator with Dirichlet boundary conditions and a random potential, a quantization theorem for the edge currents is proven. This shows that the concept of edge channels also makes sense in presence of disorder. Moreover, Gaussian bounds on the heat kernel and its covariant derivatives are obtained

    Gregariousness, Interactive Jobs and Wages

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    Gregariousness is an important aspect of human life with implications for labour market outcomes. The paper examines, to the best of our knowledge for the first time for Germany, gregariousness and social interaction at the workplace and associated wage differentials. Our empirical findings with samples from the German Socio-Economic Panel (SOEP) demonstrate that gregarious people more often work in jobs with social interaction. Furthermore, females tend to work more often in interactive jobs compared to males. There is evidence that working in an interactive job is associated with a compensating negative wage differential of 7 percent for women and non for men. Implications for wage policy are discussed.Gregariousness, social interactions, labour markets, sorting, wage differentials

    Gregariousness, interactive jobs and wages

    Get PDF
    Gregariousness is an important aspect of human life with implications for labour market outcomes. The paper examines, to the best of our knowledge for the first time for Germany, gregariousness and social interaction at the workplace and associated wage differentials. Our empirical findings with samples from the German Socio-Economic Panel (SOEP) demonstrate that gregarious people more often work in jobs with social interaction. Furthermore, females tend to work more often in interactive jobs compared to males. There is evidence that working in an interactive job is associated with a compensating negative wage differential of 7 percent for women and non for men. Implications for wage policy are discussed. --Gregariousness,social interactions,labour markets,sorting,wage differentials

    Correlated continuous-time random walks: combining scale-invariance with long-range memory for spatial and temporal dynamics

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    Standard continuous time random walk (CTRW) models are renewal processes in the sense that at each jump a new, independent pair of jump length and waiting time are chosen. Globally, anomalous diffusion emerges through action of the generalized central limit theorem leading to scale-free forms of the jump length or waiting time distributions. Here we present a modified version of recently proposed correlated CTRW processes, where we incorporate a power-law correlated noise on the level of both jump length and waiting time dynamics. We obtain a very general stochastic model, that encompasses key features of several paradigmatic models of anomalous diffusion: discontinuous, scale-free displacements as in Levy flights, scale-free waiting times as in subdiffusive CTRWs, and the long-range temporal correlations of fractional Brownian motion (FBM). We derive the exact solutions for the single-time probability density functions and extract the scaling behaviours. Interestingly, we find that different combinations of the model parameters lead to indistinguishable shapes of the emerging probability density functions and identical scaling laws. Our model will be useful to describe recent experimental single particle tracking data, that feature a combination of CTRW and FBM properties.Comment: 25 pages, IOP style, 5 figure

    Aging renewal theory and application to random walks

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    The versatility of renewal theory is owed to its abstract formulation. Renewals can be interpreted as steps of a random walk, switching events in two-state models, domain crossings of a random motion, etc. We here discuss a renewal process in which successive events are separated by scale-free waiting time periods. Among other ubiquitous long time properties, this process exhibits aging: events counted initially in a time interval [0,t] statistically strongly differ from those observed at later times [t_a,t_a+t]. In complex, disordered media, processes with scale-free waiting times play a particularly prominent role. We set up a unified analytical foundation for such anomalous dynamics by discussing in detail the distribution of the aging renewal process. We analyze its half-discrete, half-continuous nature and study its aging time evolution. These results are readily used to discuss a scale-free anomalous diffusion process, the continuous time random walk. By this we not only shed light on the profound origins of its characteristic features, such as weak ergodicity breaking. Along the way, we also add an extended discussion on aging effects. In particular, we find that the aging behavior of time and ensemble averages is conceptually very distinct, but their time scaling is identical at high ages. Finally, we show how more complex motion models are readily constructed on the basis of aging renewal dynamics.Comment: 21 pages, 7 figures, RevTe

    Diffusion and bulk flow in phloem loading - a theoretical analysis of the polymer trap mechanism in plants

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    Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular loading mechanism, active symplasmic loading, also called the polymer trap mechanism, where sucrose is transformed into heavier sugars, such as raffinose and stachyose, in the intermediary-type companion cells bordering the sieve elements in the minor veins of the phloem. Keeping the heavier sugars from diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across the relevant interfaces, without explicitly considering the chemical reactions transforming the sucrose into the heavier sugars. Based on the available data for plasmodesmata geometry, sugar concentrations and flux rates, we conclude that this mechanism can in principle function. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all the necessary water for phloem translocation would be supplied in this way with no need for additional water uptake across the plasma membranes of the phloem.Comment: 29 pages with 5 figure

    Societal Change, Care Need and Long-Term Care Workforce in Selected European Countries

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    This paper aims to show the impact of societal change on the demand and supply of long-term care workforce. As age is the major driver of the need for care the growth in the number of elderly and oldest old will increase the demand for long-term care workforce. Caregiving to the elderly is predominantly the task of the family in almost all European countries. However, the majority of European countries provide some kind of formal care either in institutions, at home or as cash benefits. The amount of provided publicly financed long-term care services and the required formal workforce spread widely across the European countries depending on the long-term care system and the financial resources. We selected five countries: Denmark, Germany, Italy, Poland and Slovakia which represent different long-term care systems and financial resources. In all studied countries the demand for long-term care workforce will increase significantly. Although also the informal care giving potential aged 50+ is expected to increase, the increase in the demand for formal care workforce is projected to be higher than the supply. The current shortage of nursing and caring personnel will be strengthened. This requires an expansion of recruitment and retention strategies.This publication was produced as part of the NEUJOBS project, funded by the European Commission through the 7th Framework Programme under contract no. 266833 (http://www.neujobs)
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