High purity bright single photon source

Using cavity-enhanced non-degenerate parametric downconversion, we have built a frequency tunable source of heralded single photons with a narrow bandwidth of 8 MHz, making it compatible with atomic quantum memories. The photon state is 70% pure single photon as characterized by a tomographic measurement and reconstruction of the quantum state, revealing a clearly negative Wigner function. Furthermore, it has a spectral brightness of ~1,500 photons/s per MHz bandwidth, making it one of the brightest single photon sources available. We also investigate the correlation function of the down-converted fields using a combination of two very distinct detection methods; photon counting and homodyne measurement.Comment: 9 pages, 4 figures; minor changes, added referenc

Work and family: associations with long-term sick-listing in Swedish women – a case-control study

<p>Abstract</p> <p>Background</p> <p>The number of Swedish women who are long-term sick-listed is high, and twice as high as for men. Also the periods of sickness absence have on average been longer for women than for men. The objective of this study was to investigate the associations between factors in work- and family life and long-term sick-listing in Swedish women.</p> <p>Methods</p> <p>This case-control study included 283 women on long-term sick-listing ≥90 days, and 250 female referents, randomly chosen, living in five counties in Sweden. Bivariate and multivariate logistic regression analyses with odds ratios were calculated to estimate the associations between long-term sick-listing and factors related to occupational work and family life.</p> <p>Results</p> <p>Long-term sick-listing in women is associated with self-reported lack of competence for work tasks (OR 2.42 1.23–11.21 log reg), workplace dissatisfaction (OR 1.89 1.14–6.62 log reg), physical workload above capacity (1.78 1.50–5.94), too high mental strain in work tasks (1.61 1.08–5.01 log reg), number of employers during work life (OR 1.39 1.35–4.03 log reg), earlier part-time work (OR 1.39 1.18–4.03 log reg), and lack of influence on working hours (OR 1.35 1.47–3.86 log reg). A younger age at first child, number of children, and main responsibility for own children was also found to be associated with long-term sick-listing. Almost all of the sick-listed women (93%) wanted to return to working life, and 54% reported they could work immediately if adjustments at work or part-time work were possible.</p> <p>Conclusion</p> <p>Factors in work and in family life could be important to consider to prevent women from being long-term sick-listed and promote their opportunities to remain in working life. Measures ought to be taken to improve their mobility in work life and control over decisions and actions regarding theirs lives.</p

Pasture–livestock dynamics with density‐dependent harvest and changing environment

We model pasture–livestock interactions by means of a predator–prey model, with the biomass vegetation as prey and the herbivores as predators. The harvesting rate is a sigmoidal function of the livestock density. We identify the necessary biological and harvest conditions for different equilibria of this model to exist. The system possesses no interior equilibrium points for the mortality rate exceeding a certain threshold. For the regime of low and moderate values of the mortality rate and a high consumption rate per animal, a unique finite and asymptotically stable state exists. We incorporate the effect of forage resource deterioration over time, causing extra decrease in the herbivore population and in the biomass density. We also include the effect of fluctuations in the availability of fodder by allowing for a seasonal periodic variation in the conversion efficiency. This results in extra oscillations superimposed on the general trends of the unperturbed system