Superconducting pipes and levitating magnets

Motivated by a beautiful demonstration of the Faraday's and Lenz's law in which a small neodymium magnet falls slowly through a conducting non-ferromagnetic tube, we consider the dynamics of a magnet falling through a superconducting pipe. Unlike the case of normal conducting pipes, in which the magnet quickly reaches the terminal velocity, inside a superconducting tube the magnet falls freely. On the other hand, to enter the pipe the magnet must overcome a large electromagnetic energy barrier. For sufficiently strong magnets, the barrier is so large that the magnet will not be able to penetrate it and will be suspended over the front edge. We calculate the work that must done to force the magnet to enter a superconducting tube. The calculations show that superconducting pipes are very efficient at screening magnetic fields. For example, the magnetic field of a dipole at the center of a short pipe of radius $a$ and length $L \approx a$ decays, in the axial direction, with a characteristic length $\xi \approx 0.26 a$. The efficient screening of the magnetic field might be useful for shielding highly sensitive superconducting quantum interference devices, SQUIDs. Finally, the motion of the magnet through a superconducting pipe is compared and contrasted to the flow of ions through a trans-membrane channel

Implementing Public Health Regulations in Developing Countries: Lessons from the OECD Countries

The enforcement of public health standards is a common problem in many developing countries. Public health agencies lack sufficient resources and, too often, enforcement mechanisms rely on slow and erratic judicial systems. These limitations can make traditional public health regulations difficult to implement. In this article, we examine innovative approaches to the implementation of public health regulations that have emerged in recent years within OECD countries. These approaches aim to improve compliance with health standards, while reducing dependence on both the legal system and the administrative resources of public health agencies. This article begins by discussing some traditional forms of public health regulations; these regulations include administrative searches and inspections as well as licensing measures. Within these traditional forms of public health regulation, there are several ways of improving compliance without substantially increasing administrative costs. These measures include public disclosure and several types of sanctions, which may escalate in severity as an actor continues to flout the public health regulation. In addition to such traditional measures, we discuss more creative approaches to reducing dependence on the judiciary and reducing administrative costs. Dependence on the judiciary can be reduced through increased reliance on alternative dispute resolution methods, such as mediation and arbitrations, as well as through the use of a public health Ombudsman. Administrative costs could also potentially be reduced through the creative use of public-private cooperation measures, such as negotiated rulemaking and self-regulating codes of conduct. Developing countries may find some useful lessons in the innovative approaches described; however, these approaches will likely need to be adapted to fit each country’s particular institutional setting

Three charged particles in the continuum. Astrophysical examples

We suggest a new adiabatic approach for description of three charged particles in the continuum. This approach is based on the Coulomb-Fourier transformation (CFT) of three body Hamiltonian, which allows to develop a scheme, alternative to Born-Oppenheimer one. The approach appears as an expansion of the kernels of corresponding integral transformations in terms of small mass-ratio parameter. To be specific, the results are presented for the system $ppe$ in the continuum. The wave function of a such system is compared with that one which is used for estimation of the rate for triple reaction $p+p+e\to d+\nu,$ which take place as a step of $pp$-cycle in the center of the Sun. The problem of microscopic screening for this particular reaction is discussed

Stereo Computation for a Single Mixture Image

This paper proposes an original problem of \emph{stereo computation from a single mixture image}-- a challenging problem that had not been researched before. The goal is to separate (\ie, unmix) a single mixture image into two constitute image layers, such that the two layers form a left-right stereo image pair, from which a valid disparity map can be recovered. This is a severely illposed problem, from one input image one effectively aims to recover three (\ie, left image, right image and a disparity map). In this work we give a novel deep-learning based solution, by jointly solving the two subtasks of image layer separation as well as stereo matching. Training our deep net is a simple task, as it does not need to have disparity maps. Extensive experiments demonstrate the efficacy of our method.Comment: Accepted by European Conference on Computer Vision (ECCV) 201

Fertility Levels, Trends and Differentials in Kenya: How Does the Own-children Method Add to Our Knowledge of the Transition?

The own-children method of fertility estimation tracks temporal changes in fertility patterns. We revisit the Kenyan fertility transition by applying the method to 1979, 1989 and 1999 censuses, and 1989, 1993, 1998 and 2003 Demographic and Health Surveys data. The method's ability to provide yearly fertility rates for periods preceding each data source adds enormous knowledge to fertility patterns. For Kenya, these trends go back through the 1960s. First, the method sheds additional light on the onset of the transition. Second, the trends highlight major differences in the onset and pace of fertility decline among regions and key sub-groups. Third, the rates for overlapping periods provide both internal and external validity checks that heighten confidence in the overall results. Last, it provides a rare opportunity to evaluate birth history fertility rates. Taken together, these estimates provide more detail than ever before regarding fertility patterns in Kenya