Local density of states of chiral Hall edge states in gyrotropic photonic clusters

We have constructed the Green's tensor for two-dimensional gyrotropic photonic clusters and have calculated their optical local density of states (LDOS). For clusters that support the chiral Hall edge states we calculate the LDOS as a function of wavele

Gun laws and sudden death: Did the Australian firearms legislation of 1996 make a difference?

Mass murders in Dunblane, United Kingdom, and Port Arthur, Australia, provoked rapid responses from the governments of both countries. Major changes to Australian laws resulted in a controversial buy-back of longarms and tighter legislation. The Australian situation enables evaluation of the effect of a national buy-back, accompanied by tightened legislation in a country with relatively secure borders. AutoRegressive Integrated Moving Average (ARIMA) was used to predict future values of the time series for homicide, suicide and accidental death before and after the 1996 National Firearms Agreement (NFA). When compared with observed values, firearm suicide was the only parameter the NFA may have influenced, although societal factors could also have influenced observed changes. The findings have profound implications for future firearm legislation policy direction

Criminal Careers Among Female Perpetrators of Family and Non-family Homicide in Australia

Knowledge of women’s pathways to serious offending, including homicide, is limited. This study contributes to a small but growing body of literature examining the criminal careers of serious female offenders by using interview data with females convicted of murder or manslaughter in Australia to examine various dimensions of their criminal careers, specifically, prevalence, frequency, age of onset, duration, and offending variety. In particular, in this study we compared criminal career dimensions across women who had killed a family member (e.g., intimate partner, children) and those whose victims were not part of the family unit (i.e., acquaintances or strangers). Our findings reveal differences between female homicide offenders who kill within and outside of the family unit. Although both groups had comparable overall lifetime prevalence of self-reported participation in criminal offending, findings indicate that participation among the family group was typically at low levels of frequency, of limited duration, and with relatively little variety in categories of offending. The family group also reported lower contact with the criminal justice system compared with the nonfamily group, and were less likely to have experienced some form of criminal/legal sanction in the 12 months prior to the homicide incident. This suggests that women who kill family members are more “conventional” than their nonfamily counterparts, in terms of having low and time-limited (i.e., short duration) lifetime participation in criminal offending

Focusing: coming to the point in metamaterials

The point of the paper is to show some limitations of geometrical optics in the analysis of subwavelength focusing. We analyze the resolution of the image of a line source radiating in the Maxwell fisheye and the Veselago-Pendry slab lens. The former optical medium is deduced from the stereographic projection of a virtual sphere and displays a heterogeneous refractive index n(r) which is proportional to the inverse of 1+r^2. The latter is described by a homogeneous, but negative, refractive index. It has been suggested that the fisheye makes a perfect lens without negative refraction [Leonhardt, Philbin arxiv:0805.4778v2]. However, we point out that the definition of super-resolution in such a heterogeneous medium should be computed with respect to the wavelength in a homogenized medium, and it is perhaps more adequate to talk about a conjugate image rather than a perfect image (the former does not necessarily contains the evanescent components of the source). We numerically find that both the Maxwell fisheye and a thick silver slab lens lead to a resolution close to lambda/3 in transverse magnetic polarization (electric field pointing orthogonal to the plane). We note a shift of the image plane in the latter lens. We also observe that two sources lead to multiple secondary images in the former lens, as confirmed from light rays travelling along geodesics of the virtual sphere. We further observe resolutions ranging from lambda/2 to nearly lambda/4 for magnetic dipoles of varying orientations of dipole moments within the fisheye in transverse electric polarization (magnetic field pointing orthogonal to the plane). Finally, we analyse the Eaton lens for which the source and its image are either located within a unit disc of air, or within a corona 1<r<2 with refractive index $n(r)=\sqrt{2/r-1}$. In both cases, the image resolution is about lambda/2.Comment: Version 2: 22 pages, 11 figures. More figures added, additional cases discussed. Misprints corrected. Keywords: Maxwell fisheye, Eaton lens; Non-Euclidean geometry; Stereographic projection; Transformation optics; Metamaterials; Perfect lens. The last version appears at J. Modern Opt. 57 (2010), no. 7, 511-52

Gun laws and sudden death: Did the Australian firearms legislation of 1996 make a difference?

Mass murders in Dunblane, United Kingdom, and Port Arthur, Australia, provoked rapid responses from the governments of both countries. Major changes to Australian laws resulted in a controversial buy-back of longarms and tighter legislation. The Australian situation enables evaluation of the effect of a national buy-back, accompanied by tightened legislation in a country with relatively secure borders. AutoRegressive Integrated Moving Average (ARIMA) was used to predict future values of the time series for homicide, suicide and accidental death before and after the 1996 National Firearms Agreement (NFA). When compared with observed values, firearm suicide was the only parameter the NFA may have influenced, although societal factors could also have influenced observed changes. The findings have profound implications for future firearm legislation policy direction

Effective Dielectric Response of Metamaterials

We use a homogenization procedure for Maxwell's equations in order to obtain in the local limit the frequency ($\omega$) dependent macroscopic dielectric response $\epsilon^M(\omega)$ of metamaterials made of natural constituents with any geometrical shape repeated periodically with any structure. We illustrate the formalism calculating $\epsilon^M(\omega)$ for several structures. For dielectric rectangular inclusions within a conducting material we obtained a very anisotropic response which changes along one direction from conductor-like at low $\omega$ to a resonant dielectric-like at large $\omega$, attaining a very small reflectance at intermediate frequencies unrelated to surface plasmon excitation and which can be tuned through geometrycal tayloring. A similar behavior is obtained for other shapes close to the percolation threshold.Comment: 16 pages 7 figures. Accepted in Phys. Rev. B (2009-06-08

Anderson Localization of Classical Waves in Weakly Scattering Metamaterials

We study the propagation and localization of classical waves in one-dimensional disordered structures composed of alternating layers of left- and right-handed materials (mixed stacks) and compare them to the structures composed of different layers of the same material (homogeneous stacks). For weakly scattering layers, we have developed an effective analytical approach and have calculated the transmission length within a wide region of the input parameters. When both refractive index and layer thickness of a mixed stack are random, the transmission length in the long-wave range of the localized regime exhibits a quadratic power wavelength dependence with the coefficients different for mixed and homogeneous stacks. Moreover, the transmission length of a mixed stack differs from reciprocal of the Lyapunov exponent of the corresponding infinite stack. In both the ballistic regime of a mixed stack and in the near long-wave region of a homogeneous stack, the transmission length of a realization is a strongly fluctuating quantity. In the far long-wave part of the ballistic region, the homogeneous stack becomes effectively uniform and the transmission length fluctuations are weaker. The crossover region from the localization to the ballistic regime is relatively narrow for both mixed and homogeneous stacks. In mixed stacks with only refractive-index disorder, Anderson localization at long wavelengths is substantially suppressed, with the localization length growing with the wavelength much faster than for homogeneous stacks. The crossover region becomes essentially wider and transmission resonances appear only in much longer stacks. All theoretical predictions are in an excellent agreement with the results of numerical simulations.Comment: 19 pages, 16 figures, submitted to PR

Modes of symmetric composite defects in two-dimensional photonic crystals

We consider the modal fields and resonance frequencies of composite defects in two-dimensional photonic crystals (PCs). Using an asymptotic method based on Green's functions, we show that the coupling matrices for the composite defect can be represented as circulant or block-circulant matrices. Using the properties of these matrices, specifically that their eigenvectors are independent of the values of the matrix elements, we obtain modal properties such as dispersion relations, modal cutoff, degeneracy, and symmetry of the mode fields. Using our formulation, we investigate defects arranged on the vertices of regular polygons as well as PC ring resonators with defects arranged on the edges of polygons. Finally, we discuss the impact of band-edge degeneracies on composite-defect modes