Enhanced and directional single photon emission in hyperbolic metamaterials

We propose an approach to enhance and direct the spontaneous emission from isolated emitters embedded inside hyperbolic metamaterials into single photon beams. The approach rests on collective plasmonic Bloch modes of hyperbolic metamaterials which propagate in highly directional beams called quantum resonance cones. We propose a pumping scheme using the transparency window of the hyperbolic metamaterial that occurs near the topological transition. Finally, we address the challenge of outcoupling these broadband resonance cones into vacuum using a dielectric bullseye grating. We give a detailed analysis of quenching and design the metamaterial to have a huge Purcell factor in a broad bandwidth inspite of the losses in the metal. Our work should help motivate experiments in the development of single photon sources for broadband emitters such as nitrogen vacancy centers in diamond.Comment: 29 pages, 9 figure

The Nature of the Peculiar Virgo Cluster Galaxies NGC 4064 and NGC 4424

We present a detailed study of the peculiar HI-deficient Virgo cluster spiral galaxies NGC 4064 and NGC 4424, using $^{12}$CO 1-0 interferometry, optical imaging and integral-field spectroscopic observations, in order to learn what type of environmental interactions have afected these galaxies. Optical imaging reveals that NGC 4424 has a strongly disturbed stellar disk, with banana-shaped isophotes and shells. NGC 4064, which lies in the cluster outskirts, possesses a relatively undisturbed outer stellar disk and a central bar. In both galaxies H-alpha emission is confined to the central kiloparsec. CO observations reveal bilobal molecular gas morphologies, with H-alpha emission peaking inside the CO lobes, implying a time sequence in the star formation process.Gas kinematics reveals strong bar-like non-circular motions in the molecular gas in both galaxies, suggesting that the material is radially infalling. In NGC 4064 the stellar kinematics reveal strong bar-like non-circular motions in the central 1 kpc. On the other hand, NGC 4424 has extremely modest stellar rotation velocities (Vmax ~ 30 km s-1), and stars are supported by random motions as far out as we can measure it. The observations suggest that the peculiarities of NGC 4424 are the result of an intermediate-mass merger plus ram pressure stripping. In the case of NGC 4064, the evidence suggests an already stripped "truncated/normal" galaxy that recently suffered a minor merger or tidal interaction with another galaxy. We propose that galaxies with "truncated/compact" H-alpha morphologies such as these are the result of the independent effects of ram pressure stripping, which removes gas from the outer disk, and gravitational interactions such as mergers, which heat stellar disks, drive gas to the central kpc and increase the central mass concentrations.Comment: 42 pages, 21 figure

Biological control networks suggest the use of biomimetic sets for combinatorial therapies

Cells are regulated by networks of controllers having many targets, and targets affected by many controllers, but these "many-to-many" combinatorial control systems are poorly understood. Here we analyze distinct cellular networks (transcription factors, microRNAs, and protein kinases) and a drug-target network. Certain network properties seem universal across systems and species, suggesting the existence of common control strategies in biology. The number of controllers is ~8% of targets and the density of links is 2.5% \pm 1.2%. Links per node are predominantly exponentially distributed, implying conservation of the average, which we explain using a mathematical model of robustness in control networks. These findings suggest that optimal pharmacological strategies may benefit from a similar, many-to-many combinatorial structure, and molecular tools are available to test this approach.Comment: 33 page