Guided-wave approaches to spectrally selective energy absorption

Results of experiments designed to demonstrate spectrally selective absorption in dielectric waveguides on semiconductor substrates are reported. These experiments were conducted with three waveguides formed by sputtering films of PSK2 glass onto silicon-oxide layers grown on silicon substrates. The three waveguide samples were studied at 633 and 532 nm. The samples differed only in the thickness of the silicon-oxide layer, specifically 256 nm, 506 nm, and 740 nm. Agreement between theoretical predictions and measurements of propagation constants (mode angles) of the six or seven modes supported by these samples was excellent. However, the loss measurements were inconclusive because of high scattering losses in the structures fabricated (in excess of 10 dB/cm). Theoretical calculations indicated that the power distribution among all the modes supported by these structures will reach its steady state value after a propagation length of only 1 mm. Accordingly, the measured loss rates were found to be almost independent of which mode was initially excited. The excellent agreement between theory and experiment leads to the conclusion that low loss waveguides confirm the predicted loss rates

New nonlinear dielectric materials: Linear electrorheological fluids under the influence of electrostriction

The usual approach to the development of new nonlinear dielectric materials focuses on the search for materials in which the components possess an inherently large nonlinear dielectric response. In contrast, based on thermodynamics, we have presented a first-principles approach to obtain the electrostriction-induced effective third-order nonlinear susceptibility for the electrorheological (ER) fluids in which the components have inherent linear, rather than nonlinear, responses. In detail, this kind of nonlinear susceptibility is in general of about the same order of magnitude as the compressibility of the linear ER fluid at constant pressure. Moreover, our approach has been demonstrated in excellent agreement with a different statistical method. Thus, such linear ER fluids can serve as a new nonlinear dielectric material.Comment: 11 page

PCBs : exposures, effects, remediation, and regulation with special emphasis on PCBs in schools

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Environmental Science and Pollution Research 23 (2016): 1971-1974, doi:10.1007/s11356-015-5774-y.The Eighth International PCB Workshop: PCBs in Schools was held in Woods Hole, MA, October 5-9, 2014, and was attended by more than 130 scientists and other interested persons, including citizen’s groups and concerned parents. The program included a wide range of thematic areas. Presentations addressed essential questions and progress toward understanding mechanisms of PCB toxication and risks of PCB exposure. Presentations were also held illuminating several key PCB contamination problems.2016-12-0

Decolonizing Jeremiah: identity, narratives and power in religious tradition

Talstra, E. [Promotor]Wit, J.H. de [Copromotor

Chemical impacts in fish and shellfish from Cape Cod and Massachusetts Bays

This paper is not subject to U.S. copyright. The definitive version was published in Environment Cape Cod 1, no. 3 (1998): 68-85.Mununichogs, soft shell clams, and blue mussels from some or all of 10 sites in Boston Harbor and Massachusetts and Cape Cod Bays were examined histologically: a suite of pathological changes previously known to be associated with chemical contamination were found in animals from the more contaminated sites. In particular, liver tumors were evident in 14% of the adult mununichogs from the Island End River, a tributary of the Mystic River in Boston Harbor. Additionally, a number of pathologies previously shown to be associated with chemical exposure were seen in the two bivalve species at a number of contaminated sites. Induction of cytochrome P45() IA (CYPIA) was also seen in muntntichogs from the more contaminated sites: CYPIA induction is a biochemical change associated with exposure to dioxin and other planar halogenated and aromatic hydrocarbons. These findings suggest that there are measurable biochemical and pathological changes in intertidal fish and shellfish from the more contaminated parts of the Massachusetts Bays system. These types of changes were less evident in the two reference sites in Cape Cod Bay

Cascading nonlinearities in an organic single crystal core fiber: The Cerenkov regime

The large nonlinear phase shifts imparted to the fundamental beam during Cerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to nonlinear phase shifts produced by the second order nonlinear coupling of the guided fundamental mode and the component of the Cerenkov second harmonic field trapped in the fiber cladding