Photonic crystal and microstructured fibers:Making fibers better by leaving bits out

Presents a collection of slides covering the following topics: photonic crystal; microstructured fibers; transparency; glass; fibre cladding; hollow core fibres; fibre fabrication; fiber attenuation; fibre dispersion; low-loss fibres; fiber laser; mode locked laser; four wave mixing; and atomic optics

Land Grant Application- Knight, Jonathan (Waterborough)

Land grant application submitted to the Maine Land Office for Jonathan Knight for service in the Revolutionary War.https://digitalmaine.com/revolutionary_war_me_land_office/1541/thumbnail.jp

Global/local stress analysis of composite panels

A method for performing a global/local stress analysis is described, and its capabilities are demonstrated. The method employs spline interpolation functions which satisfy the linear plate bending equation to determine displacements and rotations from a global model which are used as boundary conditions for the local model. Then, the local model is analyzed independent of the global model of the structure. This approach can be used to determine local, detailed stress states for specific structural regions using independent, refined local models which exploit information from less-refined global models. The method presented is not restricted to having a priori knowledge of the location of the regions requiring local detailed stress analysis. This approach also reduces the computational effort necessary to obtain the detailed stress state. Criteria for applying the method are developed. The effectiveness of the method is demonstrated using a classical stress concentration problem and a graphite-epoxy blade-stiffened panel with a discontinuous stiffener

Whispering-gallery-mode dye laser emission from liquid in a capillary fiber

Bibliography: p. 153-170.The nature of optical whispering-gallery-mode resonances in a layered microcylinder is investigated numerically by studying the scattering characteristics and the internal electromagnetic fields of a normally-illuminated cladded dielectric fiber calculated using the boundary-value method. Computed resonant mode configurations are compared to the better-known results for homogeneous spheres and cylinders and coated spheres. It is shown that high-Q whispering-gallery-mode resonances can be supported by the curved interface between the core and cladding regions of a layered fiber if the core refractive index is sufficiently greater than that of the outer layer, and that these modes can be directly related to the so-called morphology-dependent resonances of a homogeneous cylinder of the same size and relative refractive index as the fiber core. The implications of these resonant modes for inelastic optical processes are made clear by developing a model for optical emissions from a molecule in the core of a capillary fiber. The results of the model show that the transition rates of molecules in the fiber core and near to the core/cladding interface are enhanced at frequencies corresponding to cavity resonances. It is shown experimentally that these high-Q cavity modes can be excited to above the threshold for laser emission by providing gain in the fiber core material. We have used a refractive dye-doped solvent as a gain medium and a fused-silica capillary to form the resonant cavity. Upon optical excitation of the dye by illuminating the fiber normally with the green beam from a frequency-doubled Nd:YAG laser, laser emission is emitted from the fiber core in the plane perpendicular to the fiber axis. We explain the novel spatial and spectral dependences of the laser emission in terms of the calculated frequencies and Q-values of the resonant cavity modes and the bulk properties of the cavity medium. We show that the thresholds observed in the laser system can be explained using a simplified rate-equation approach, and that this also explains some of the other observed features of the emissions. The heating of the dye solvent during a laser pulse has an observable effect on the resonance mode locations due to the temperature dependence of the refractive index. We demonstrate the use of observed laser spectra to determine the size and taper of the capillary fiber core

Sing On, Ntsikana: The Story of Christian Music among the Xhosa People of South Africa

The Xhosa, an African people united by language and history, occupied a large portion of what is now eastern South Africa prior to the arrival of Europeans. After the arrival of Christianity through the Europeans, one of the earliest Xhosa converts, Ntsikana, was also the first Xhosa to compose music meant to worship their newfound Savior. Though this music in the traditional Xhosa style lay dormant for some time, enthusiastic Xhosa ministers in the past century have done much to learn from and expand upon the musical, spiritual legacy of Ntsikana. A unique blend of European and South African music has birthed among Xhosa Christians a distinct flavor of worship, which, though reflecting foreign influences, strongly retains indigenous traditions