Gravitational Field of a Spinning Mass as an Example of Algebraically Special Metrics

It is shown that the ordinary semiclassical theory of the absorption of light by exciton states is not completely satisfactory (in contrast to the case of absorption due to interband transitions). A more complete theory is developed. It is shown that excitons are approximate bosons, and, in interaction with the electromagnetic field, the exciton field plays the role of the classical polarization field. The eigenstates of the system of crystal and radiation field are mixtures of photons and excitons. The ordinary one-quantum optical lifetime of an excitation is infinite. Absorption occurs only when "three-body" processes are introduced. The theory includes "local field" effects, leading to the Lorentz local field correction when it is applicable. A Smakula equation for the oscillator strength in terms of the integrated absorption constant is derived.

a Quantum-Mechanical Theory of the Contribution of Excitons to the Complex Dielectric Constant of Crystals.

Squeezed states of the electromagnetic field have been generated by nondegenerate four-wave mixing due to Na atoms in an optical cavity. The optical noise in the cavity, comprised of primarily vacuum fluctuations and a small component of spontaneous emission from the pumped Na atoms, is amplified in one quadrature of the optical field and deamplified in the other quadrature. These quadrature components are measured with a balanced homodyne detector. The total noise level in the deamplified quadrature drops below the vacuum noise level.

Observation of squeezed states generated by four-wave mixing in an optical cavity

13. 벼잎선충의 약제처리 방법별 방제 효과

Understanding the biodegradation of polyurethanes: From classical implants to tissue engineering materials

For decades, the surface-plasmon-polariton wave guided by the interface of simple isotropic materials dominated the scene. However, in recent times research on electromagnetic surface waves guided by planar interfaces has expanded into new and exciting areas. In the 1990's research focused on advancing knowledge of the newly discovered Dyakonov wave. More recently, much of the surface wave research is motivated by the proliferation of nanotechnology and the growing number of materials available with novel properties. This book leads the reader from the relatively simple surface-plasmon-polariton wave with isotropic materials to the latest research on various types of electromagnetic surface waves guided by the interfaces of complex materials enabled by recent developments in nanotechnology. This includes: Dyakonov waves guided by interfaces formed with columnar thin films, Dyakonov-Tamm waves guided by interfaces formed with sculptured thin films, and multiple modes of surface-plasmon-polariton waves guided by the interface of a metal and a periodically varying dielectric material. Gathers research from the past 5 years in a single comprehensive view of electromagnetic surface waves. Written by the foremost experts and researchers in the field.Layered presentation explains topics with an introductory overview level up to a highly technical level.

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Electromagnetic Surface Waves: A Modern Perspective

The propagation of plane waves in a Faraday chiral medium is investigated. Conditions for the phase velocity to be directed opposite to the direction of power flow are derived for propagation in an arbitrary direction; simplified conditions which apply to propagation parallel to the distinguished axis are also established. These negative phase-velocity conditions are explored numerically using a representative Faraday chiral medium, arising from the homogenization of an isotropic chiral medium and a magnetically biased ferrite. It is demonstrated that the phase velocity may be directed opposite to power flow, provided that the gyrotropic parameter of the ferrite component medium is sufficiently large compared with the corresponding nongyrotropic permeability parameters.

Plane waves with negative phase velocity in Faraday chiral mediums.

New polyurethane heart valve prosthesis: design, manufacture and evaluation

Six flexible-leaflet prosthetic heart valves, fabricated from a polyetherurethaneurea (PEUE), underwent long-term fatigue and calcification testing. Three valves exceeded 800 million cycles without failure. Three valves failed at 775, 460, and 544 million cycles, respectively. Calcification was observed with and without associated failure in regions of high strain. Comparison with similar valves fabricated from a polyetherurethane (PEU) suggests that the PEU is likely to fail sooner as a valve leaflet. Localized calcification developed in PEUE leaflets at the primary failure site of PEU leaflets, close to the coaptation region of the three leaflets. The failure mode in PEU valves had the appearance of abrasion wear associated with calcification. High strains in the same area may render the PEUE leaflets vulnerable to calcification. Intrinsic calcification of this type, however, is a long-term phenomenon unlikely to cause early valve failure. Both polymers performed similarly during static in vitro and in vivo calcification testing and demonstrated a much lesser degree of calcification than bioprosthetic types of valve materials. Polyurethane valves can achieve the durabilities required of an implantable prosthetic valve, equaling the fatigue life of currently available bioprosthetic valves.

Tom G. Mackay

Papers

Electromagnetic Surface Waves: A Modern Perspective

Plane waves with negative phase velocity in Faraday chiral mediums.

New polyurethane heart valve prosthesis: design, manufacture and evaluation

Polyurethane heart valves : Fatigue failure, calcification, and polyurethane structure

Calcification and fatigue failure in a polyurethane heart valve