Generalized 4 ×\times 4 Matrix Formalism for Light Propagation in Anisotropic Stratified Media: Study of Surface Phonon Polaritons in Polar Dielectric Heterostructures

We present a generalized 4 $\times$ 4 matrix formalism for the description of light propagation in birefringent stratified media. In contrast to previous work, our algorithm is capable of treating arbitrarily anisotropic or isotropic, absorbing or non-absorbing materials and is free of discontinous solutions. We calculate the reflection and transmission coefficients and derive equations for the electric field distribution for any number of layers. The algorithm is easily comprehensible and can be straight forwardly implemented in a computer program. To demonstrate the capabilities of the approach, we calculate the reflectivities, electric field distributions, and dispersion curves for surface phonon polaritons excited in the Otto geometry for selected model systems, where we observe several distinct phenomena ranging from critical coupling to mode splitting, and surface phonon polaritons in hyperbolic media

Theory of enhanced dynamical photo-thermal bi-stability effects in cuprous oxide/organic hybrid heterostructure

We theoretically demonstrate the formation of multiple bi-stability regions in the temperature pattern on the interface between a cuprous oxide quantum well and DCM2:CA:PS organic compound. The Frenkel molecular exciton of the DCM2 is brought into resonance with the $1S$ quadrupole Wannier-Mott exciton in the cuprous oxide by "solvatochromism" with CA. The resulting hybrid is thermalized with surrounding helium bath. This leads to strongly non-linear temperature dependence of the laser field detuning from the quadrupole exciton energy band which is associated with the temperature induced red shift of the Wannier exciton energy. Numerical up and down-scan for the detuning reveals hysteresis-like temperature distribution. The obtained \emph{multiple} bi-stability regions are at least three orders of magnitude bigger ($meV$) than the experimentally observed bi-stability in bulk cuprous oxide ($\mu eV$). The effective absorption curve exhibits highly asymmetrical behavior for the Frenkel-like (above the $1S$ energy) and Wannier-like (below the $1S$ energy) branches of the hybrid.Comment: 6 pages, 7 Figure

Second Harmonic Generation from Phononic Epsilon-Near-Zero Berreman Modes in Ultrathin Polar Crystal Films

Immense optical field enhancement was predicted to occur for the Berreman mode in ultrathin films at frequencies in the vicinity of epsilon near zero (ENZ). Here, we report the first experimental proof of this prediction in the mid-infrared by probing the resonantly enhanced second harmonic generation (SHG) at the longitudinal optic phonon frequency from a deeply subwavelength-thin aluminum nitride (AlN) film. Employing a transfer matrix formalism, we show that the field enhancement is completely localized inside the AlN layer, revealing that the observed SHG signal of the Berreman mode is solely generated in the AlN film. Our results demonstrate that ENZ Berreman modes in intrinsically low-loss polar dielectric crystals constitute a promising platform for nonlinear nanophotonic applications

Second harmonic generation from strongly coupled localized and propagating phonon-polariton modes

We experimentally investigate second harmonic generation from strongly coupled localized and propagative phonon polariton modes in arrays of silicon carbide nanopillars. Our results clearly demonstrate the hybrid nature of the system's eigenmodes and distinct manifestation of strong coupling in the linear and nonlinear response. While in linear reflectivity the intensity of the two strongly-coupled branches is essentially symmetric and well explained by their respective localized or propagative components, the second harmonic signal presents a strong asymmetry. Analyzing it in detail, we reveal the importance of interference effects between the nonlinear polarization terms originating in the bulk and in the phonon polariton modes, respectively.Comment: 7 pages, 4 figure

Strong Coupling of Epsilon-Near-Zero Phonon Polaritons in Polar Dielectric Heterostructures

We report the first observation of epsilon near zero (ENZ) phonon polaritons in an ultrathin AlN film fully hybridized with surface phonon polaritons (SPhP) supported by the adjacent SiC substrate. Employing a strong coupling model for the analysis of the dispersion and electric field distribution in these hybridized modes, we show that they share the most prominent features of the two precursor modes. The novel ENZ-SPhP coupled polaritons with a highly propagative character and deeply sub-wavelength light confinement can be utilized as building blocks for future infrared and terahertz (THz) nanophotonic integration and communication devices

The Role of White-tailed Deer (Odocoileus virginianus) in the Epidemiology of Bovine Viral Diarrhea Virus

Bovine viral diarrhea virus (BVDV) is the prototypic member of the genus Pestivirus in the family Flaviviridae. Infections with BVDV cause substantial economic losses to the cattle industries, prompting the introduction of organized control programs in several countries. In North America, these control programs are mainly focused on the identification and removal of persistently infected (PI) cattle, the main reservoir for BVDV. Further measures include the enhancement of BVDV-specific immunity through vaccination and the implementation of biosecure farming practices. For the successful execution of these control measures, knowledge of the epidemiology of BVDV must be complete, including the recognition of other potential sources of the virus. Bovine viral diarrhea virus does not possess strict host-specificity and infections have been demonstrated in over 50 species in the mammalian order Artiodactyla. In North America, the white-tailed deer (Odocoileus virginianus) is the most abundant free-ranging ruminant, and evidence of BVDV infections was described in serological surveys and a single experimental inoculation of fawns. However, susceptibility of white-tailed deer to BVDV infection does not alone imply or prove a role in the epidemiology of the virus or prove the existence of a wildlife reservoir. Additional criteria including shedding and maintenance of BVDV and sufficient contact to cause spill-back infections to cattle must be met to cause concern for developing BVDV control measures. The overall goal of this research was to examine whether white-tailed deer could be a wildlife reservoir for BVDV, and studies were developed on the basis of the necessary criteria for wildlife reservoirs. For each experiment, free-ranging white-tailed deer were captured by cannon-net or dart-gun and translocated to a captive research facility. Upon capture, all animals were determined to be free from BVDV and antibodies against BVDV. Persistently infected cattle are the most efficient source of BVDV and constitute the major source of transmission of the virus within and among cattle herds. If the phenomenon of persistent infection could occur in white-tailed deer, these PI animals could shed and maintain BVDV, and pose a potential threat to BVDV control and eradication programs. To assess the outcome of fetal infection in white-tailed deer, in our first experiment, nine pregnant does were inoculated intranasally with 106 CCID50 each of a BVDV 1 (BJ) and BVDV 2 (PA131) strain. In this study, only one doe gave birth and delivered a live fawn and a mummified fetus. The live fawn was determined to be PI with BVDV 2 by serial virus isolation from serum, buffy coat, and nasal swabs; immunohistochemistry on skin samples; and RT-PCR on serum. Analogous to PI cattle, the fawn continuously shed BVDV, as indicated by BVDV positive nasal swab samples. Central to the development of a wildlife reservoir is interspecific contact and transmission of BVDV, which were the focus of our second experiment. At approximately 50 days of pregnancy, seven female and one male white-tailed deer were cohabitated with two PI cattle. In a pen of approximately two acres, both species shared feed and water sources for a period of 60 days. Cohabitation of species resulted in the transmission of BVDV from PI cattle to deer, as indicated by seroconversion in all adult deer. Transplacental transmission of BVDV was demonstrated in four of seven pregnancies, as two stillborn twin fetuses and three live singletons were infected with BVDV at birth. All singlet fawns were demonstrated to be PI by immunohistochemistry and ELISA on skin samples, and RT-PCR and virus isolation procedures on blood and tissues samples. These findings demonstrate that BVDV may efficiently cross the species barrier to provide a potential alternative niche to ensure viral survival and propagation. Shedding of BVDV as demonstrated in the PI fawns may result in maintenance of the virus within populations of white-tailed deer, and this would be central to perpetuation of a wildlife reservoir. To evaluate the potential for intraspecific transmission of BVDV and the potential for BVDV maintenance in white-tailed deer, six pregnant does were cohabitated with a PI fawn during the first trimester of pregnancy. All does gave birth to live fawns and no reproductive losses were observed. At birth, evidence of BVDV infection was identified in two singlet fawns, of which one was determined to be PI by repeated serum RT-nPCR, whole blood virus isolation and immunohistochemistry. The birth of a PI fawn in this study strengthens the possibility of continuous intrapopulational propagation of BVDV and the potential for indefinite maintenance of the virus in deer. While the experiment was designed to emulate a wild population, the size of the captive deer facility limits possible extrapolations to free-ranging populations in which various factors may influence the transmission and maintenance of BVDV. We therefore studied free-ranging white-tailed deer in Alabama for evidence of BVDV infection by assessing serum and skin samples collected from hunter-harvested deer. Upon site visits to deer processing units, 165 serum samples and 406 skin biopsies were collected and analyzed by virus neutralization and immunohistochemistry, respectively. Two serum samples contained virus neutralizing antibodies, and one skin sample was positive on immunohistochemistry. The viral antigen distribution in the skin sample was similar to that of PI cattle, indicating the existence of free-ranging PI white-tailed deer in Alabama. A central question to control of BVDV in US cattle populations is whether the virus can be transmitted from PI white-tailed deer to susceptible cattle. Our research indicated that survival of PI white-tailed deer appears to be reduced, prompting the research question whether clinically ill or dead PI deer may be a source of BVDV and hamper current control programs. We therefore evaluated the transmission of BVDV to cattle exposed to carcasses of PI white-tailed deer. In two trials, steers were exposed to the carcass of PI fawn A (BVDV 2) or PI fawn B (BVDV 1). One steer from each of two groups was separated into a pen with the carcass. We chose to expose only one steer from each group to the carcass to simulate the effects of bovine contact networks and social hierarchies on the transmission of BVDV. Following 8 hours, the single steer from each trial was commingled with four other steers for 28 days. Subsequently, one steer was inoculated intranasally with spleen homogenate from fawn A, and two steers were inoculated intranasally or intravenously with spleen homogenate from fawn B as infection controls. Steers in both trials made contact with the carcass, but BVDV transmission did not occur. The intranasally inoculated control for trial A and the intravenously inoculated control for trial B became viremic and seroconverted. Although both PI fawn carcasses were potentially infectious, this study indicated exposure of a single inquisitive bovid to a PI fawn carcass did not result in transmission of BVDV. The results of our research indicate that BVDV infections in white-tailed deer share many features with infections in cattle, indicating a potential for the development of a wildlife reservoir in this species. This development, however, would be influenced by various endogenous and exogenous factors and further research is needed to aid in the successful control of BVDV

Bulk properties of rotating nuclei and the validity of the liquid drop model at finite angular momenta

Out of self-consistent semi-classical calculations performed within the so-called Extended Thomas-Fermi approach for 212 nuclei at all even angular momentum values I ranging between 0 and 80 \hbar and using the Skyrme SkM* effective force, the I-dependence of associated liquid drop model parameters has been studied. The latter have been obtained trough separate fits of the calculated values of the strong interaction as well as direct and exchange Coulomb energies. The theoretical data basis so obtained, has allowed to make a rough quantitative assessment of the variation with I of the usual volume and surface energy parameters up to spin of \sim 30-40 \hbar. As a result of the combined variation of the surface and Coulomb energies, it has been shown that this I-dependence results in a significant enhancement of the fission stability of very heavy nuclei, balancing thus partially the well-known instability due to centrifugal forces.Comment: 27 pages, LaTeX (elsart) with 13 embeded postscript figure