Quantized vortices and superflow in arbitrary dimensions: Structure, energetics and dynamics

The structure and energetics of superflow around quantized vortices, and the motion inherited by these vortices from this superflow, are explored in the general setting of the superfluidity of helium-four in arbitrary dimensions. The vortices may be idealized as objects of co-dimension two, such as one-dimensional loops and two-dimensional closed surfaces, respectively, in the cases of three- and four-dimensional superfluidity. By using the analogy between vorticial superflow and Ampere-Maxwell magnetostatics, the equilibrium superflow containing any specified collection of vortices is constructed. The energy of the superflow is found to take on a simple form for vortices that are smooth and asymptotically large, compared with the vortex core size. The motion of vortices is analyzed in general, as well as for the special cases of hyper-spherical and weakly distorted hyper-planar vortices. In all dimensions, vortex motion reflects vortex geometry. In dimension four and higher, this includes not only extrinsic but also intrinsic aspects of the vortex shape, which enter via the first and second fundamental forms of classical geometry. For hyper-spherical vortices, which generalize the vortex rings of three dimensional superfluidity, the energy-momentum relation is determined. Simple scaling arguments recover the essential features of these results, up to numerical and logarithmic factors.Comment: 35 pages, 7 figure

A global reference database of crowdsourced cropland data collected using the Geo-Wiki platform

A global reference data set on cropland was collected through a crowdsourcing campaign using the Geo-Wiki crowdsourcing tool. The campaign lasted three weeks, with over 80 participants from around the world reviewing almost 36,000 sample units, focussing on cropland identification. For quality assessment purposes, two additional data sets are provided. The first is a control set of 1,793 sample locations validated by students trained in satellite image interpretation. This data set was used to assess the quality of the crowd as the campaign progressed. The second data set contains 60 expert validations for additional evaluation of the quality of the contributions. All data sets are split into two parts: the first part shows all areas classified as cropland and the second part shows cropland average per location and user. After further processing, the data presented here might be suitable to validate and compare medium and high resolution cropland maps generated using remote sensing. These could also be used to train classification algorithms for developing new maps of land cover and cropland extent

Financial Globalization and Economic Policies

We review the large literature on various economic policies that could help developing economies effectively manage the process of financial globalization. Our central findings indicate that policies promoting financial sector development, institutional quality and trade openness appear to help developing countries derive the benefits of globalization. Similarly, sound macroeconomic policies are an important prerequisite for ensuring that financial integration is beneficial. However, our analysis also suggests that the relationship between financial integration and economic policies is a complex one and that there are unavoidable tensions inherent in evaluating the risks and benefits associated with financial globalization. In light of these tensions, structural and macroeconomic policies often need to be tailored to take into account country specific circumstances to improve the risk-benefit tradeoffs of financial integration. Ultimately, it is essential to see financial integration not just as an isolated policy goal but as part of a broader package of reforms and supportive macroeconomic policies

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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