Size of rings in two dimensions

The authors report enumeration results for the radius of gyration and caliper size distribution of self-avoiding unrooted polygons of up to 28 steps, on the square lattice. The (second moment) radius of gyration series is sufficiently smooth to allow verification of the theoretical prediction v(rings)=v(walks) to 0.2% accuracy

The variance of the number of prime polynomials in short intervals and in residue classes

We resolve a function field version of two conjectures concerning the variance of the number of primes in short intervals (Goldston and Montgomery) and in arithmetic progressions (Hooley). A crucial ingredient in our work are recent equidistribution results of N. Katz.Comment: Revised according to referees' comment

Oscillational instabilities in single mode acoustics levitators

An extention of standard results for the acoustic force on an object in a single-mode resonant chamber yields predictions for the onset of oscillational instabilities when objects are levitated or positioned in these chambers. The authors' results are consistent with those of experimental investigators. The present approach accounts for the effects of time delays in the response of a cavity to the motion of an object inside of it. Quantitative features of the instabilities are investigated. The experimental conditions required for sample stability, saturation of sample oscillations, hysteretic effects, and the loss of ability to levitate are discussed

Live-timer method of automatic dead-time correction for precision counting

Automatic correction for dead time losses in nuclear counting experiments is implemented by a simple live timer arrangement in which each counting interval is extended for compensation for the dead time during that interval. this method eliminates repetitious manual calculations, source of error, and dependence upon paralysis shifts

The First Measurement of Cassiopeia A's Forward Shock Expansion Rate

We have obtained a second epoch observation of the Cassiopeia A supernova remnant (SNR) with the Chandra X-ray Observatory to measure detailed X-ray proper motions for the first time. Both epoch observations are 50 ks exposures of the ACIS-S3 chip and they are separated by 2 years. Measurements of the thin X-ray continuum dominated filaments located around the edge of the remnant (that are identified with the forward shock) show expansion rates from 0.02%/yr to 0.33%/yr. Many of these filaments are therefore significantly decelerated. Their median value of 0.21%/yr is equal to the median expansion of the bright ring (0.21%/yr) as measured with Einstein and ROSAT. This presents a conundrum if the motion of the bright ring is indicative of the reverse shock speed. We have also re-evaluated the motion of the radio bright ring with emphasis on angle-averaged emissivity profiles. Our new measurement of the expansion of the angle-averaged radio bright ring is 0.07 plus or minus 0.03%/yr, somewhat slower than the previous radio measurements of 0.11%/yr which were sensitive to the motions of small-scale features. We propose that the expansion of the small-scale bright ring features in the optical, X-ray, and radio do not represent the expansion of the reverse shock, but rather represent a brightness-weighted average of ejecta passing through and being decelerated by the reverse shock. The motion of the reverse shock, itself, is then represented by the motion of the angle-averaged emissivity profile of the radio bright ring.Comment: accepted to Ap

Disorder induced transition into a one-dimensional Wigner glass

The destruction of quasi-long range crystalline order as a consequence of strong disorder effects is shown to accompany the strict localization of all classical plasma modes of one-dimensional Wigner crystals at T=0. We construct a phase diagram that relates the structural phase properties of Wigner crystals to a plasmon delocalization transition recently reported. Deep inside the strictly localized phase of the strong disorder regime, we observe ``glass-like'' behavior. However, well into the critical phase with a plasmon mobility edge, the system retains its crystalline composition. We predict that a transition between the two phases occurs at a critical value of the relative disorder strength. This transition has an experimental signature in the AC conductivity as a local maximum of the largest spectral amplitude as a function of the relative disorder strength.Comment: 5 pages, revtex. Typo regarding localization length exponent corrected. Should read 1 / \delt

Measurement of the Integrated Faraday Rotations of BL Lac Objects

We present the results of multi-frequency polarization VLA observations of radio sources from the complete sample of northern, radio-bright BL Lac objects compiled by H. Kuhr and G. Schmidt. These were used to determine the integrated rotation measures of 18 objects, 15 of which had never been measured previously, which hindered analysis of the intrinsic polarization properties of objects in the complete sample. These measurements make it possible to correct the observed orientations of the linear polarizations of these sources for the effect of Faraday rotation. The most probable origin for Faraday rotation in these objects is the Galactic interstellar medium. The results presented complete measurements of the integrated rotation measures for all 34 sources in the complete sample of BL Lac objects.Comment: 9 pages, 7 figure

Hindsight

As a reflexive practice, hindsight enables a subject to re-observe how moments in the once-present past come to bear on a now-present future. Such observations enable us to make (new) sense of our life\u27s trajectory, re-casting seemingly inconsequential moments as “prophetic” happenings. In this essay, I revisit a series of connected moments in my past to examine how actions I took as a then-heterosexual man influenced the construction of my now-queer identity