Monolithically integrated active optical devices

Considerations relevant to the monolithic integration of optical detectors, lasers, and modulators with high speed amplifiers are discussed. Some design considerations for representative subsystems in the GaAs-AlGaAs and GaInAs-InP materials systems are described. Results of a detailed numerical design of an electro-optical birefringent filter for monolithic integration with a laser diode is described, and early experimental results on monolithic integration of broadband MESFET amplifiers with photoconductive detectors are reported

SDiff(2) and uniqueness of the Pleba\'{n}ski equation

The group of area preserving diffeomorphisms showed importance in the problems of self-dual gravity and integrability theory. We discuss how representations of this infinite-dimensional Lie group can arise in mathematical physics from pure local considerations. Then using Lie algebra extensions and cohomology we derive the second Pleba\'{n}ski equation and its geometry. We do not use K\"ahler or other additional structures but obtain the equation solely from the geometry of area preserving transformations group. We conclude that the Pleba\'{n}ski equation is Lie remarkable

Are We Walking the Talk? Questions of Structure and Agency in the Research on Teaching in Adult Education

Despite current prevalence of constructivist epistemologies, the practice of teaching adults continues to reflect representational approaches to meaning. In this roundtable discussion, we explore the use of Giddens’ theory of structuration as a framework for deepening our understanding of the lack of change in teaching

Impact analysis of composite aircraft structures

The impact analysis of composite aircraft structures is discussed. Topics discussed include: background remarks on aircraft crashworthiness; comments on modeling strategies for crashworthiness simulation; initial study of simulation of progressive failure of an aircraft component constructed of composite material; and research direction in composite characterization for impact analysis

Partisanship, health behavior, and policy attitudes in the early stages of the COVID-19 pandemic

ObjectiveTo study the U.S. public's health behaviors, attitudes, and policy opinions about COVID-19 in the earliest weeks of the national health crisis (March 20-23, 2020).MethodWe designed and fielded an original representative survey of 3,000 American adults between March 20-23, 2020 to collect data on a battery of 38 health-related behaviors, government policy preferences on COVID-19 response and worries about the pandemic. We test for partisan differences COVID-19 related policy attitudes and behaviors, measured in three different ways: party affiliation, intended 2020 Presidential vote, and self-placed ideological positioning. Our multivariate approach adjusts for a wide range of individual demographic and geographic characteristics that might confound the relationship between partisanship and health behaviors, attitudes, and preferences.ResultsWe find that partisanship-measured as party identification, support for President Trump, or left-right ideological positioning-explains differences in Americans across a wide range of health behaviors and policy preferences. We find no consistent evidence that controlling for individual news consumption, the local policy environment, and local pandemic-related deaths erases the observed partisan differences in health behaviors, beliefs, and attitudes. In further analyses, we use a LASSO regression approach to select predictors, and find that a partisanship indicator is the most commonly selected predictor across the 38 dependent variables that we study.ConclusionOur analysis of individual self-reported behavior, attitudes, and policy preferences in response to COVID-19 reveals that partisanship played a central role in shaping individual responses in the earliest months of the COVID-19 pandemic. These results indicate that partisan differences in responding to a national public health emergency were entrenched from the earliest days of the pandemic

Ion activation energy delivered to wounds by atmospheric pressure dielectric-barrier discharges: sputtering of lipid-like surfaces

The application of atmospheric pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. These effects are attributed to production of UV photon fluxes, electric fields and beneficial radicals which intersect with biological reaction chains, and to energetic ions bombarding the surface. In this paper we report on results from a computational investigation of the ion energy and angular distributions (IEADs) in a dielectric-barrier discharge sustained in air incident directly on cell membranes for small dry and wet wounds in human skin. We found that ion energies in excess of 20–30 eV can be delivered onto cell membranes of dry wounds, and up to 60 eV onto the liquid interface of the wet wound. The details of the IEADs depend on the orientation of the cell membrane and on the relative location of the plasma streamer to the wound. Using results from a molecular dynamics simulation of ion sputter probabilities of typical lipid-like material, we show that prolonged exposure of the cell membrane to such IEADs can produce significant carbon removal.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98590/1/0022-3727_45_11_115203.pd

Bellman equations for optimal feedback control of qubit states

Using results from quantum filtering theory and methods from classical control theory, we derive an optimal control strategy for an open two-level system (a qubit in interaction with the electromagnetic field) controlled by a laser. The aim is to optimally choose the laser's amplitude and phase in order to drive the system into a desired state. The Bellman equations are obtained for the case of diffusive and counting measurements for vacuum field states. A full exact solution of the optimal control problem is given for a system with simpler, linear, dynamics. These linear dynamics can be obtained physically by considering a two-level atom in a strongly driven, heavily damped, optical cavity.Comment: 10 pages, no figures, replaced the simpler model in section