Radio electrons and magnetic fields in the galactic halo

Radiating electron density in galactic halo and cosmic ray dat

Milgrom's revision of cosmic dynamics: Amending Newton's laws or Keplers?

Milgrom's recent revision of Newtonian dynamics was introduced to eliminate the inference that large quantities of invisible mass exist in galaxies. Simple examples show that a Milgrom acceleration, in the form presented so far, imply other far-reaching changes in dynamics. The momentum of an isolated system is not conserved, and the usual theorem for center-of-mass motion of any system does not hold. Naive applications require extreme caution. The model fails to provide a complete description of particle dynamics and should be thought of as a revision of Kepler's laws rather than Newton's. The Milgrom acceleration also implies fundamental changes in cosmology. A quasi-Newtonian calculation adapted from Newtonian cosmology suggests that a Milgrom universe will recollapse even if the classical closure parameter theta is less than 1. The solution, however, fails to satisfy the cosmological principle. Reasons for the breakdown of this calculation are examined. A theory of gravitation needed before the behavior of a Milgrom universe can be predicted

A diophantine equation for sums of consecutive like powers

We show that the diophantine equation $n^\ell+(n+1)^\ell + ...+ (n+k)^\ell=(n+k+1)^\ell+ ...+ (n+2k)^\ell$ has no solutions in positive integers $k,n \ge 1$ for all $\ell \ge 3$.Comment: History of the problem adde

On the detectability of infrared echo arcs around supernova 1987A

The ring-like interstellar visual echoes of radii 33 and 54 arcsec detected around SN 1987A should coincide with infrared echoes (thermal reradiation) from dust at T approximately equal to 15 to 30 K. Whether these infrared echoes are detectable at present is considered. They will be brightest at approximately 100 microns, the range of the Texas infrared photometer. Detectability depends on the ratio zeta congruent to tan(sub a)/tan(sub s)P(theta), where tan(sub a) and tan(sub s) are the visual absorption and scattering optical thicknesses of the echo layer, and P is the phase function function for small-angle scattering (theta approximately equal to 2 to 4 degrees). Zeta approximately greater than 1 is needed for a detectable signal (approximately 0.3 Jy), but zeta cannot be much less than 1; otherwise the visual echoes could not be as bright as they are. Typical dust mixtures of Mathis-Rumpl-Nordsieck type have zeta much less than 1. Zeta remains small even if a population of very small grains with power-law index as steep as approximately 5.5 is added. A population with even more small grains and/or fewer large grains could have a zeta similar to 1 and be detectable at present, but this seems unlikely. The echoes will move, but should remain accessible for many years and should be detected eventually

A Cryptographic Escrow for Treaty Declarations and Step-by-Step Verification

The verification of arms-control and disarmament agreements requires states to provide declarations, including information on sensitive military sites and assets. There are important cases, however, where negotiations of these agreements are impeded because states are reluctant to provide any such data, because of concerns about prematurely handing over militarily significant information. To address this challenge, we present a cryptographic escrow that allows a state to make a complete declaration of sites and assets at the outset and commit to its content, but only reveal the sensitive information therein sequentially. Combined with an inspection regime, our escrow allows for step-by-step verification of the correctness and completeness of the initial declaration so that the information release and inspections keep pace with parallel diplomatic and political processes. We apply this approach to the possible denuclearization of North Korea. Such approach can be applied, however, to any agreement requiring the sharing of sensitive information.Comment: 14 pages, 4 figure

Just Say No: Authority, Disobedience, and Individuation in Some of Sam Peckinpah’s Minor Films

Sam Peckinpah is best known for his films The Wild Bunch (1969) and Pat Garrett and Billy the Kid (1973), and quite a bit of the existing scholarly work on Peckinpah focuses on these two films; what’s more, much of the work that does exist on his other films tends to be subjective and celebratory. The aim of this project is to critically and soberly examine Peckinpah’s relatively minor works and from particular perspectives. Specifically, this dissertation focuses on one of the major thematic threads that runs through all of the director’s films, both major and minor: how ordinary people individuate themselves through their opposition to power and capital. For Peckinpah, power takes many forms. God (and religion, generally) is an integral character in The Ballad of Cable Hogue (1970), for example, and violent mobs, the police, and corrupt businessmen and politicians serve as antagonists in some of the other films examined here. Peckinpah’s protagonists all battle these forces, to varying degrees of success, and in turn attempt to affirm their own identities through this rejection. In addition to the film scholars used in this project, Erich Fromm, Carl Jung, and David Harvey are a few of the thinkers employed in my analysis of these films, primarily Peckinpah’s road movies and non-Westerns