Double-peak spectral energy density of GRBs and the true identity of GRB 031203

A double-peak spectral-energy-density of gamma-rays, similar to that observed in blazars, is expected in gamma-ray bursts (GRBs) produced in supernova (SN) explosions. The second peak, which is formed by inverse Compton scattering of ambient SN light by cosmic ray electrons accelerated by the jets from the SN explosion, has a much higher peak-energy than the first ordinary peak. However, in X-ray flashes (XRFs), which in the cannonball (CB) model are normal GRBs viewed farther off axis, the first peak-energy is shifted to the soft X-ray region while the second peak-energy moves to the MeV range. In far-off-axis GRBs, such as GRBs 980425 and 031203, the second peak may have been confused with the normal GRB peak. In most GRBs, which have been observed so far, the gamma-ray detectors ran out of statistics far below the second peak. However, in bright GRBs, the two peaks may be resolved by simultaneous measurements with SWIFT and GLAST.Comment: The estimated soft X-ray fluence in GRB 031203 was replaced in the text and Fig. 3 with the correct estimate by Vaughan et al. Corrected typo

The cannonball model of long GRBs - overview

During the past ten years, the predictions of the cannonball (CB) model of gamma ray bursts (GRBs) were repeatedly confronted with the mounting data from space- and ground-based observations of GRBs and their afterglows (AGs). The two underlying radiation mechanisms of the model, inverse Compton scattering (ICS) and synchrotron radiation (SR), provided an accurate description of the prompt and afterglow emission in all of the many well-sampled GRBs that were studied. Simple as they are, these two mechanisms and the burst environment were shown to generate the observed rich structure of the GRB light-curves at all observed frequencies and times.Comment: Invited talk, to be published in the proceedings of Cefalu 2009 workshop `Probing stellar populations out to the distant universe', Cefalu, Sicily, Italy, September 7-19, 200

Aeration/destratification in Lake Evergreen, McLean County, Illinois

"Prepared for the City of Bloomington.

New bounds on the neutrino magnetic moment from the plasma induced neutrino chirality flip in a supernova

The neutrino chirality-flip process under the conditions of the supernova core is investigated in detail with the plasma polarization effects in the photon propagator taken into account, in a more consistent way than in earlier publications. It is shown in part that the contribution of the proton fraction of plasma is essential. New upper bounds on the neutrino magnetic moment are obtained: mu_nu < (0.5 - 1.1) 10^{-12} mu_B from the limit on the supernova core luminosity for nu_R emission, and mu_nu < (0.4 - 0.6) 10^{-12} mu_B from the limit on the averaged time of the neutrino spin-flip. The best upper bound on the neutrino magnetic moment from SN1987A is improved by the factor of 3 to 7.Comment: 19 pages, LaTeX, 7 EPS figures, submitted to Journal of Cosmology and Astroparticle Physic

Concurrent bandits and cognitive radio networks

We consider the problem of multiple users targeting the arms of a single multi-armed stochastic bandit. The motivation for this problem comes from cognitive radio networks, where selfish users need to coexist without any side communication between them, implicit cooperation or common control. Even the number of users may be unknown and can vary as users join or leave the network. We propose an algorithm that combines an $\epsilon$-greedy learning rule with a collision avoidance mechanism. We analyze its regret with respect to the system-wide optimum and show that sub-linear regret can be obtained in this setting. Experiments show dramatic improvement compared to other algorithms for this setting

Incompressible Turbulence as Nonlocal Field Theory

It is well known that incompressible turbulence is nonlocal in real space because sound speed is infinite in incompressible fluids. The equation in Fourier space indicates that it is nonlocal in Fourier space as well. Contrast this with Burgers equation which is local in real space. Note that the sound speed in Burgers equation is zero. In our presentation we will contrast these two equations using nonlocal field theory. Energy spectrum and renormalized parameters will be discussed.Comment: 7 pages; Talk presented in Conference on "Perspectives in Nonlinear Dynamics (PNLD 2004)" held in Chennai, 200

Impact testing to determine the mechanical properties of articular cartilage in isolation and on bone

The original publication is available at www.springerlink.comNon peer reviewedPostprin

Unidentified EGRET Sources and the Extragalactic Gamma-Ray Background

The large majority of EGRET point sources remain to this day without an identified low-energy counterpart. Whatever the nature of the EGRET unidentified sources, faint unresolved objects of the same class must have a contribution to the diffuse gamma-ray background: if most unidentified objects are extragalactic, faint unresolved sources of the same class contribute to the background, as a distinct extragalactic population; on the other hand, if most unidentified sources are Galactic, their counterparts in external galaxies will contribute to the unresolved emission from these systems. Understanding this component of the gamma-ray background, along with other guaranteed contributions from known sources, is essential in any attempt to use gamma-ray observations to constrain exotic high-energy physics. Here, we follow an empirical approach to estimate whether a potential contribution of unidentified sources to the extragalactic gamma-ray background is likely to be important, and we find that it is. Additionally, we comment on how the anticipated GLAST measurement of the diffuse gamma-ray background will change, depending on the nature of the majority of these sources.Comment: 6 pages, 3 figures, to appear in proceedings of "The Multi-Messenger Approach to High Energy Gamma-Ray Sources", Barcelona, 4-7 July 2006; comments welcom