Critical currents and high temperature superconductors

The experimental information on critical currents and epitaxial thin films of high temperature superconductors is summarized. Experiments carried out to measure critical currents across single grain boundaries are described. A variety of mechanisms responsible for limiting currents in films as well as across grain boundaries are presented and their predictions compared with experimental data

Stochastic gradient descent performs variational inference, converges to limit cycles for deep networks

Stochastic gradient descent (SGD) is widely believed to perform implicit regularization when used to train deep neural networks, but the precise manner in which this occurs has thus far been elusive. We prove that SGD minimizes an average potential over the posterior distribution of weights along with an entropic regularization term. This potential is however not the original loss function in general. So SGD does perform variational inference, but for a different loss than the one used to compute the gradients. Even more surprisingly, SGD does not even converge in the classical sense: we show that the most likely trajectories of SGD for deep networks do not behave like Brownian motion around critical points. Instead, they resemble closed loops with deterministic components. We prove that such "out-of-equilibrium" behavior is a consequence of highly non-isotropic gradient noise in SGD; the covariance matrix of mini-batch gradients for deep networks has a rank as small as 1% of its dimension. We provide extensive empirical validation of these claims, proven in the appendix

Building an IDE for the Calculational Derivation of Imperative Programs

In this paper, we describe an IDE called CAPS (Calculational Assistant for Programming from Specifications) for the interactive, calculational derivation of imperative programs. In building CAPS, our aim has been to make the IDE accessible to non-experts while retaining the overall flavor of the pen-and-paper calculational style. We discuss the overall architecture of the CAPS system, the main features of the IDE, the GUI design, and the trade-offs involved.Comment: In Proceedings F-IDE 2015, arXiv:1508.0338

Response of Corn and Palmer amaranth to Mesotrione

Mesotrione is a herbicide used for the selective pre- and post-emergence control of a wide range of broadleaf and grass weeds in corn (Zea mays). It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) which leads to stop biosynthesis of plastoquinone, a key factor in the synthesis of carotenoid pigment. The depletion of carotenoids leading to bleaching symptoms followed by necrosis in sensitive plants. Palmer amaranth (Amaranth Palmeri) is one of the major weeds in corn production system. This study was conducted to test the hypothesis that mesotrione may be effective to control Palmer amaranth and safe for use in corn. Therefore, the objective of this research was to evaluate response of corn and Palmer amaranth to mesotrione. Corn and Palmer amaranth plants were treated with mesotrione at 105 g ai ha-1,and plant survival data was collected at 3 week after application. There was no injury reported to any of the corn plant, and plant survival rate was reported 100%. However, Palmer amaranth plants showed bleaching symptoms followed by necrosis and plant death. Only 12.5% Palmer amaranth plants survived after mesotrione application. These results demonstrated the tolerance of corn and sensitivity of Palmer amaranth to mesotrione