The physics of the oscillating lightning

The lightning is proposed to start in a limited region of electric breakdown field. A growing charge pool in a cumulonimbus cloud is likely to produce such a field in its outer layers. When the field is not aligned with the potential surfaces, the electric force pushes positive charge in one direction and negative in the opposite. Self inductance develops and an embryo open electric circuit is born. Oscillations swiftly grow in strength when potential energy of the cloud is released. The channel extends in steps during those cycle stages where charge is crammed into the channel terminals. Electrostatic consequences of a narrow conductor among the cloud charges are computed. The conductor is charged by influence to such a degree that the charge is bound to leak out to the ambient air and appear as a charge sheath some distance off the channel. Ample energy is released to sustain the oscillations. The period increases with channel length and agrees well with observed time between steps. A ground strike leads to a shock pulse travelling up the channel

The radiative transfer equations for Compton scattering of polarized low frequency radiation on a hot electron gas

We deduce the equations that describe how polarized radiation is Comptonized by a hot electron gas. Low frequencies are considered, and the equations are expanded to second order in electron velocities. Induced scattering terms are included and a Maxwellian velocity distribution for the electrons is assumed. The special case of an axisymmetric radiation field is also considered, and the corresponding radiative transfer equations are found. Our results correct errors and misprints in previosly published transfer equations. The extension to a moving electron gas is made, and the radiative transfer equations are deduced to second order in gas velocity. We use the equations to study polarization in the Sunyaev-Zeldovich effect.Comment: 9 pages, 2 figuers, MNRAS-LaTeX-style Submitted to the Monthly Notices of the Royal astronomical Societ

Deep Imaging of the Double Quasar 0957+561: New Constraints on H_0

We present new results from extremely deep, high-resolution images of the field around the double quasar QSO 0957+561. A possible gravitational arc system near the double quasar has recently been reported, which, if real, would set strong constraints on determinations of the Hubble constant from the time delay in the double quasar. We find that both the morphology and the colors of the claimed arc systems suggest that they are chance alignments of three and two different objects, and not gravitationally lensed arcs. Hence, the constraints on $H_0$-determinations from the arcs are not valid. Also, a small group of galaxies at $z=0.5$ near the line-of-sight which was required to have a very large mass in the physically interesting arc models, is most likely insignificant. From our deep images we are able to use weak lensing of faint background galaxies in the field to map the gravitational potential in the main cluster. This sets new constraints on determinations of $H_0$. We find that the Hubble constant is constrained to be less than 70km/(s Mpc), if the time delay between the two images of the QSO is equal to or larger than 1.1 years.Comment: (uuencoded and compressed postscipt including 3 figures); 14 page

Colored Speech: Cross Burnings, Epistemics, and the Triumph of the Crits?

This Essay examines the Court\u27s recent decision in Virginia v. Black. It argues that Black signifies a different approach to the constitutionality of statutes regulating cross burnings. It shows how the Court\u27s conservatives have essentially accepted the intellectual framework and the mode of analysis suggested previously by the critical race theorists. In particular, this Essay explores the role that Justice Thomas plays in the case. The Essay explains Justice Thomas\u27s active participation as a matter of epistemic authority and epistemic deference

Stochastic Prediction of Multi-Agent Interactions from Partial Observations

We present a method that learns to integrate temporal information, from a learned dynamics model, with ambiguous visual information, from a learned vision model, in the context of interacting agents. Our method is based on a graph-structured variational recurrent neural network (Graph-VRNN), which is trained end-to-end to infer the current state of the (partially observed) world, as well as to forecast future states. We show that our method outperforms various baselines on two sports datasets, one based on real basketball trajectories, and one generated by a soccer game engine.Comment: ICLR 2019 camera read