Christopher Keith Ratley and Eric Paul Stanton in a Joint Senior Voice Recital

This is the program for the joint senior voice recital of baritone Christopher Keith Ratley and baritone Eric Paul Stanton. Pianist Kristi Pettit assisted Ratley; pianist Suzanne Noris assisted Stanton. The recital took place on March 2, 1993, in the Mabee Fine Arts Center Recital Hall

High-brightness lasers with spectral beam combining on silicon

Modern implementations of absorption spectroscopy and infrared-countermeasures demand advanced performance and integration of high-brightness lasers, especially in the molecular fingerprint spectral region. These applications, along with others in communication, remote-sensing, and medicine, benefit from the light source comprising a multitude of frequencies. To realize this technology, a single multi-spectral optical beam of near-diffraction-limited divergence is created by combining the outputs from an array of laser sources. Full integration of such a laser is possible with direct bonding of several epitaxially-grown chips to a single silicon (Si) substrate. In this platform, an array of lasers is defined with each gain material, creating a densely spaced set of wavelengths similar to wavelength division multiplexing used in communications.Scaling the brightness of a laser typically involves increasing the active volume to produce more output power. In the direction transverse to the light propagation, larger geometries compromise the beam quality. Lengthening the cavity provides only limited scaling of the output power due to the internal losses. Individual integrated lasers have low brightness due to combination of thermal effects and high optical intensities. With heterogeneous integration, many lasers can be spectrally combined on a single integrated chip to scale brightness in a compact platform. Recent demonstrations of 2.0-µm diode and 4.8-µm quantum cascade lasers on Si have extended this heterogeneous platform beyond the telecommunications band to the mid-infrared.In this work, low-loss beam combining elements spanning the visible to the mid-infrared are developed and a high-brightness multi-spectral laser is demonstrated in the range of 4.6–4.7-µm wavelengths. An architecture is presented where light is combined in multiple stages: first within the gain-bandwidth of each laser material and then coarsely between each spectral band to a single output waveguide. All components are demonstrated on a common material platform with a Si substrate, which lends feasibility to the complete system integration. Particular attention is focused on improving the efficiency of arrayed waveguide gratings (AWGs), used in the dense wavelength combining stage. This requires development of a refined characterization technique involving AWGs in a ring-resonator configuration to reduce measurement uncertainty. New levels of low-loss are achieved for visible, near-infrared, and mid-infrared multiplexing devices. Also, a multi-spectral laser in the mid-infrared is demonstrated by integrating an array of quantum cascade lasers and an AWG with Si waveguides. The output power and spectra are measured, demonstrating efficient beam combining and power scaling. Thus, a bright laser source in the mid-infrared has been demonstrated, along with an architecture and the components for incorporating visible and near-infrared optical bands

Excitonic effects on coherent phonon dynamics in single wall carbon nanotubes

We discuss how excitons can affect the generation of coherent radial breathing modes in ultrafast spectroscopy of single wall carbon nanotubes. Photoexcited excitons can be localized spatially and give rise to a spatially distributed driving force in real space which involves many phonon wavevectors of the exciton-phonon interaction. The equation of motion for the coherent phonons is modeled phenomenologically by the Klein-Gordon equation, which we solve for the oscillation amplitudes as a function of space and time. By averaging the calculated amplitudes per nanotube length, we obtain time-dependent coherent phonon amplitudes that resemble the homogeneous oscillations that are observed in some pump-probe experiments. We interpret this result to mean that the experiments are only able to see a spatial average of coherent phonon oscillations over the wavelength of light in carbon nanotubes and the microscopic details are averaged out. Our interpretation is justified by calculating the time-dependent absorption spectra resulting from the macroscopic atomic displacements induced by the coherent phonon oscillations. The calculated coherent phonon spectra including excitonic effects show the experimentally observed symmetric peaks at the nanotube transition energies in contrast to the asymmetric peaks that would be obtained if excitonic effects were not included.Comment: submitted to Phys. Rev. B on 7 May 2013, revised on 17 July and 13 August 2013, published 30 August 201

How anthocyanin mutants respond to stress: the need to distinguish between stress tolerance and maximal vigour

Background: Anthocyanins are produced by plants in response to diverse stresses. Mutants that block the anthocyanin biosynthetic pathway (ABP) at various steps can easily be compared across numerous abiotic stresses. Hypothesis: Anthocyanins or their precursors are required for stress tolerance. Thus, ABP loss-of-function mutants should have proportionately lower fitness than wildtype plants under stress, compared with benign conditions. In contrast, a decrease in maximal vigour - the general capacity for growth and fecundity - should be most pronounced under benign conditions that allow luxuriant growth by the most vigorous genotypes. Tests: Determine whether, under stressful conditions, ABP loss-of-function mutants have relatively lower fitness than wildtype plants. Also, test for reduced maximal vigour by determining whether ABP mutants have comparatively decreased fitness under optimal (\u27benign\u27) growing conditions. Organism: Arabidopsis thaliana loss-of-function mutants (representing all steps in the ABP), as well as wildtype plants, in two genetic backgrounds. Methods: We grew plants under near-optimal conditions and five stress treatments (UV-B, drought, cold, low Ca:Mg, high Ni). We estimated relative fitness as an individual\u27s lifetime fertility, relative to the mean wildtype fertility in a given treatment. Results: Stress treatments significantly reduced lifetime fertility of wildtype and mutant lines. Wildtypes outperformed anthocyanin-deficient mutants under benign conditions, but as the stress increased, the difference between wildtype and mutant fitness diminished. Fitness did not increase with a mutation\u27s sequential position in the ABP, nor was there an effect of the ability to produce flavonols on fertility. Conclusions: Mutations in the ABP did not reduce stress tolerance. Rather, the loss of ABP function reduced maximal vigour, most evidently in near-optimal growth conditions. © 2010 Eric J. von Wettberg

Micro-resonator soliton generated directly with a diode laser

An external-cavity diode laser is reported with ultralow noise, high power coupled to a fiber, and fast tunability. These characteristics enable the generation of an optical frequency comb in a silica micro-resonator with a single-soliton state. Neither an optical modulator nor an amplifier was used in the experiment. This demonstration greatly simplifies the soliton generation setup and represents a significant step forward to a fully integrated soliton comb system.Comment: 7 pages, 5 figure

Macroscopic observations of diel fish movements around a shallow water artificial reef using a mid-frequency horizontal-looking sonar

Author Posting. © Acoustical Society of America, 2018. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 144 (2018): 1424-1434. doi:10.1121/1.5054013.The twilight feeding migration of fish around a shallow water artificial reef (a shipwreck) was observed by a horizontal-looking, mid-frequency sonar. The sonar operated at frequencies between 1.8 and 3.6 kHz and consisted of a co-located source and horizontal line array deployed at 4 km from the reef. The experiment was conducted in a well-mixed shallow water waveguide which is conducive to characterizing fish aggregations at these distances. Large aggregations of fish were repeatedly seen to emerge rapidly from the shipwreck at dusk, disperse into the surrounding area during the night, and quickly converge back to the shipwreck at dawn. This is a rare, macroscopic observation of an ecologically-important reef fish behavior, delivered at the level of aggregations, instead of individual fish tracks that have been documented previously. The significance of this observation on sonar performance associated with target detection in the presence of fish clutter is discussed based on analyses of echo intensity and statistics. Building on previous studies of long-range fish echoes, this study further substantiates the unique utility of such sonar systems as an ecosystem monitoring tool, and illustrates the importance of considering the impact of the presence of fish on sonar applications.We thank Jay Grove from the NOAA Southeast Fisheries Science Center for help in identifying potential fish species near the shipwreck sites. We also thank Jie Yang, B. Todd Hefner, and Kevin Williams at the Applied Physics Laboratory, University of Washington (APL-UW) for discussion on data processing and results interpretation. The study is supported by the Office of Naval Research and the Science & Engineering Enrichment & Development (SEED) Postdoctoral Fellowship from APL-UW.2019-03-1

Manganese Oxide Thin Films Prepared by Nonaqueous Sol-Gel Processing: Preferential Formation of Birnessite

High quality manganese oxide thin films with smooth surfaces and even thicknesses have been prepared with a nonaqueous sol–gel process involving reduction of tetraethylammonium permanganate in methanol. Spin-coated films have been cast onto soft glass, quartz, and Ni foil substrates, with two coats being applied for optimum crystallization. The addition of alkali metal cations as dopants results in exclusive formation of the layered birnessite phase. By contrast, analogous reactions in bulk sol–gel reactions yield birnessite, tunneled, and spinel phases depending on the dopant cation. XRD patterns confirm the formation of well-crystallized birnessite. SEM images of Li-, Na-, and K–birnessite reveal extremely smooth films having uniform thickness of less than 0.5 μm. Thin films of Rb– and Cs–birnessite have more fractured and uneven surfaces as a result of some precipitation during the sol–gel transformation. All films consist of densely packed particles of about 0.1 μm. When tetrabutylammonium permanganate is used instead of tetraethylammonium permanganate, the sol–gel reaction yields amorphous manganese oxide as the result of diluted Mn sites in the xerogel film. Bilayer films have been prepared by casting an overcoat of K–birnessite onto an Na–birnessite film. However, Auger depth profiling indicates considerable mixing between the adjacent layers

Extensive Pneumatization of the Temporal Bone and Articular Eminence: An Incidental Finding in a Patient With Facial Pain. Case Report and Review of Literature

A 53-year-old Caucasian female presented to the Oral Medicine Department at the hospital of the University of Pennsylvania for consultation regarding facial pain. A panoramic radiograph revealed multilocular radiolucencies in the right articular eminence. A CT scan was then performed, and the radiolucencies were determined to be pneumatization of the articular eminence