The fundamental mechanism behind directive beaming at broadside for various structures will be explored. These include Fabry-Pérot type of resonant-cavity antennas, low-permittivity metamaterial substrate antennas composed of a wire medium slab, and optical directive beaming due to plasmonic effects. In all cases it will be shown that the fundamental explanation for the directive beaming effect...

We have simulated a population of young spin-powered pulsars and computed the beaming pattern and light curves for the three main geometrical models: polar cap emission, two-pole caustic (“slot gap”) emission and outer magnetosphere emission. The light curve shapes depend sensitively on the magnetic inclination α and viewing angle ζ. We present the results as maps of observables such as peak mu...

We present 1.4 GHz VLA observations of the variability of radio sources in the Lockman Hole region at the level of ≥ 100µJy on timescales of 17 months and 19 days. These data indicate that the areal density of highly variable sources at this level is < 5 × 10 −3 arcmin −2. We set an upper limit of 2% to the fraction of 50 to 100µJy sources that are highly variable (∆S ≥ 50%). These results impl...

The angular dependencies of the local field enhancement and the Raman emission enhancement are investigated, numerically and experimentally, for a plasmonic crystal double resonance SERS substrate consisting of a periodic array of gold disks above a gold film. We find that the local field enhancement is very sensitive to the incident angle. The Raman emission enhancement has a strong angular de...

Existing near-eye display designs struggle to balance between multiple trade-offs such as form factor, weight, computational requirements, and battery life. These design are major obstacles on the path towards an all-day usable display. In this work, we address these by, paradoxically, removing from displays. We present beaming displays, a new type of system that uses projector all passive wear...

The issue of the possible presence or absence of jets in GRBs is here re-examined for GRB991216, which has a claimed half-opening beaming angle of θ◦ = 3 ◦. We compare and contrast our theoretically predicted afterglow luminosity in the 2–10 keV band for spherically symmetric versus jetted emission. Jetted emission can be excluded and data analysis confirms spherical symmetry. These theoretical...

We experimentally demonstrate tunable radiation from a periodic array of plasmonic nanoscatterers, tailored to convert surface plasmon polaritons into directive leaky modes. Extending our previous studies on efficient directional beaming based on leaky-wave radiation from periodic gratings driven by a subwavelength slit, we experimentally show dynamic beam sweeping by tuning the directional lea...

This work is part of a systematic re-analysis program of all the data of GammaRay Burst (GRB) X-ray afterglows observed so far, in order to constrain the GRB models. We present here a systematic analysis of those afterglows observed by XMMNewton between January 2000 and March 2004. This dataset includes GRB 011211 and GRB 030329. We have obtained spectra, light curves and colors for these after...

We summarize our model for long-duration gamma ray bursts (GRBs) that fits the redshift (z) distributions measured with Swift and missions before Swift, and the pre-Swift GRB jet opening-angle distribution inferred from achromatic breaks in the optical light curves. We find that the comoving rate density of GRB sources exhibits positive evolution to z > ∼ 3 – 5, whereas the star formation rate ...