Transmission Studies of Left-handed Materials

Left-handed materials are studied numerically using an improved version of the transfer-matrix method. The transmission, reflection, the phase of the reflection and the absorption are calculated and compared with experiments for both single split-ring resonators (SRR) with negative permeability and left-handed materials (LHMs) which have both the permittivity and permeability negative. Our results suggest ways of positively identifying materials that have both permittivity and permeability negative, from materials that have either permeability or permittivity negative

Transmission Losses in Left-handed Materials

We numerically analyze the origin of the transmission losses in left-handed structures. Our data confirms that left handed structures can have very good transmission properties, in spite of the expectable dispersion of their effective permeability and refraction index. The large permittivity of the metallic components improves the transmission. High losses, observed in recent experiments, could be explained by the absorption of the dielectric board

A spherical perfect lens

It has been recently proved that a slab of negative refractive index material acts as a perfect lens in that it makes accessible the sub-wavelength image information contained in the evanescent modes of a source. Here we elaborate on perfect lens solutions to spherical shells of negative refractive material where magnification of the near-field images becomes possible. The negative refractive materials then need to be spatially dispersive with $\epsilon(r) \sim 1/r$ and $\mu(r)\sim 1/r$. We concentrate on lens-like solutions for the extreme near-field limit. Then the conditions for the TM and TE polarized modes become independent of $\mu$ and $\epsilon$ respectively.Comment: Revtex4, 9 pages, 2 figures (eps

Resonant and anti-resonant frequency dependence of the effective parameters of metamaterials

We present a numerical study of the electromagnetic response of the metamaterial elements that are usedto construct materials with negative refractive index. For an array of split ring resonators (SRR) we find that the resonant behavior of the effective magnetic permeability is accompanied by an anti-resonant behavior of the effective permittivity. In addition, the imaginary parts of the effective permittivity and permeability are opposite in sign. We also observe an identical resonant versus anti-resonant frequency dependence of the effective materials parameters for a periodic array of thin metallic wires with cuts placed periodically along the length of the wire, with roles of the permittivity and permeability reversed from the SRR case. We show in a simple manner that the finite unit cell size is responsible for the anti-resonant behavior

A review of size and geometrical factors influencing resonant frequencies in metamaterials

Although metamaterials and so-called left-handed media have originated from theoretical considerations, it is only by their practical fabrication and the measurement of their properties that they have gained credibility and can fulfil the potential of their predicted properties. In this review we consider some of the more generally applicable fabrication methods and changes in geometry as they have progressed, exhibiting resonant frequencies ranging from radio waves to the visible optical region

The modest professor:Interpretive charity and interpretive humility in John Rawls's lectures on the history of political philosophy

Governmen

Metamaterials proposed as perfect magnetoelectrics

Magnetoelectric susceptibility of a metamaterial built from split ring resonators have been investigated both experimentally and within an equivalent circuit model. The absolute values have been shown to exceed by two orders of magnitude that of classical magnetoelectric materials. The metamaterial investigated reaches the theoretically predicted value of the magnetoelectric susceptibility which is equal to the geometric average of the electric and magnetic susceptibilities.Comment: 5 pages, 3 figure

Guided Modes in Negative Refractive Index Waveguides

We study linear guided waves propagating in a slab waveguide made of a negative-refraction- index material, the so-called left-handed waveguide. We reveal that the guided waves in left-handed waveguides possess a number of peculiar properties, such as the absence of the fundamental modes, mode double degeneracy, and sign-varying energy ux. In particular, we predict the existence of novel types of guided waves with a dipole-vortex structure of the Pointing vector.Comment: 4 pages, 4 figure

RELATIONSHIP OF RACCOON ROAD-KILL DATA TO HIGH-DENSITY MARINE TURTLE NESTING

Four ycars of data from a hiyh-density n~arine turtle nesting hcach at John D. MacArthur Beach Statc Park, Florida wcrc examined along with data on raccoon (Procyon lotor.) ruad-kills from adjaccnt roads, and data on park attendance (as an index of local traffic) to make infcrcnces about raccoon activity patterns relative to turtle ncsting. Raccoon road-kills were found Lo diminish subsiantially during turtle nesting, even though local traffic was constant or increasing. Opossums (Didelphis virginiana). the only other maminal consistcntly foluid as road-kills, did not show a decrease during ti~rtlen esting season, but they are not known as a primary predator of turtle nests. We concluded that duriny turtlc nestiny raccoons are drawn to the beach to prey on the abundant food resource of turtle eggs, and they do not leave the beach until the end of turtle nesting season. High nu~nbcrso f raccoon road-kills during the fall-wintcr, followed by a decrease in the spring around the start of turtle nesting season, might be ured as indicators to initiate management actions to protect turtle nests