An exploding glass ?

We propose a connection between self-similar, focusing dynamics in nonlinear partial differential equations (PDEs) and macroscopic dynamic features of the glass transition. In particular, we explore the divergence of the appropriate relaxation times in the case of hard spheres as the limit of random close packing is approached. We illustrate the analogy in the critical case, and suggest a ``normal form'' that can capture the onset of dynamic self-similarity in both phenomena.Comment: 8 pages, 2 figure

Perceiving Exploding Tropes

The topic of this paper is the perception of properties. It is argued that the perception of properties allows for a distinction between the sense of the identity and the sense of the qualitative nature of a property. So, for example, we might perceive a property as being identical over time even though it is presented as more and more determinate. Thus, you might see an object first as red and then as crimson red. In this case, the property is perceived as identical over time, even though the sense of the qualitative nature (the redness, the crimson redness) of the property is changing. The distinction between the sense of identity and the sense of quality is explicated in terms of perceiving a particular property, a trope, and perceiving it as an instance of a universal. It is subsequently argued that the perceived tropes cannot constitute the phenomenal character of the perceptual experience

Criteria for Core-Collapse Supernova Explosions by the Neutrino Mechanism

We investigate the criteria for successful core-collapse supernova explosions by the neutrino mechanism. We find that a critical-luminosity/mass-accretion-rate condition distinguishes non-exploding from exploding models in hydrodynamic one-dimensional (1D) and two-dimensional (2D) simulations. We present 95 such simulations that parametrically explore the dependence on neutrino luminosity, mass accretion rate, resolution, and dimensionality. While radial oscillations mediate the transition between 1D accretion (non-exploding) and exploding simulations, the non-radial standing accretion shock instability characterizes 2D simulations. We find that it is useful to compare the average dwell time of matter in the gain region with the corresponding heating timescale, but that tracking the residence time distribution function of tracer particles better describes the complex flows in multi-dimensional simulations. Integral quantities such as the net heating rate, heating efficiency, and mass in the gain region decrease with time in non-exploding models, but for 2D exploding models, increase before, during, and after explosion. At the onset of explosion in 2D, the heating efficiency is $\sim$2% to $\sim$5% and the mass in the gain region is $\sim$0.005 M_{\sun} to $\sim$0.01 M_{\sun}. Importantly, we find that the critical luminosity for explosions in 2D is $\sim$70% of the critical luminosity required in 1D. This result is not sensitive to resolution or whether the 2D computational domain is a quadrant or the full 180$^{\circ}$. We suggest that the relaxation of the explosion condition in going from 1D to 2D (and to, perhaps, 3D) is of a general character and is not limited by the parametric nature of this study.Comment: 32 pages in emulateapj, including 17 figures, accepted for publication in ApJ, included changes suggested by the refere

Fast Radio Bursts and White Hole Signals

We estimate the size of a primordial black hole exploding today via a white hole transition, and the power in the resulting explosion, using a simple model. We point out that Fast Radio Bursts, strong signals with millisecond duration, probably extragalactic and having unknown source, have wavelength not far from the expected size of the exploding hole. We also discuss the possible higher energy components of the signal.Comment: 5 page

Exploding bridgewire detonator simulator

Tests indicate that electric detonator simulators of the exploding bridgewire type will not fire as a result of the application of a direct current power of one watt for 5 minutes. The detonator also will not fire if the protective gap fails and the firing stimulus is inadvertently applied

Exploding Wire as a Light Source in Flash Photolysis

The exploding wire technique has been developed for use as a light source in flash photolysis. The method consists of discharging a bank of condensers, via a mechanical switch through a thin Nichrome wire. The wire explodes, emitting light rich in the ultraviolet region in less than a millisecond. The luminous efficiency in the 200 to 330 mµ region is of the order of 10% of the input. The minimum electrical energy input necessary to produce an explosion is equal to the energy required to vaporize the wire. The light output of the exploding wire as measured by uranyl oxalate actinometry and acetone photolysis is proportional to the electrical energy input. It was found to be highly reproducible. It was further observed that the exploding wire behaves as a line source. Because of the absence of a quartz or Pyrex tube in this source, it may find application in the far as well as in the near ultraviolet and in the visible spectral regions

Temperatures of Exploding Nuclei

Breakup temperatures in central collisions of 197Au + 197Au at bombarding energies E/A = 50 to 200 MeV were determined with two methods. Isotope temperatures, deduced from double ratios of hydrogen, helium, and lithium isotopic yields, increase monotonically with bombarding energy from 5 MeV to 12 MeV, in qualitative agreement with a scenario of chemical freeze-out after adiabatic expansion. Excited-state temperatures, derived from yield ratios of states in 4He, 5Li, 6Li, and 8Be, are about 5 MeV, independent of the projectile energy, and seem to reflect the internal temperature of fragments at their final separation from the system. PACS numbers: 25.70.Mn, 25.70.Pq, 25.75.-qComment: 10 pages, RevTeX with 4 included figures; Also available from http://www-kp3.gsi.de/www/kp3/aladin_publications.htm