4,327 research outputs found
Benchmarking Utility Clean Energy Deployment: 2014
This report assembles data from more than 10 sources, including state Renewable Portfolio Standard (RPS) annual reports, U.S. Securities and Exchange Commission 10-K filings and Public Utility Commission reports, to show how 32 of the largest U.S. investor-owned electric utility holding companies stack up on renewable energy and energy efficiency
Doctor of Philosophy
dissertationMedical intervention to restore motor function lost due to injury, stroke, or disease is increasingly common. Recent research in this field, known as functional electrical stimulation (FES), has produced a new generation of electrode devices that greatly enhance selectivity of access to neural populations, enabling-for the first time-restoration of motor function approaching what healthy humans enjoy. Research with these devices, however, has been severely hampered by the lack of a stimulation platform and control algorithms capable of exploring their full potential. The following dissertation presents the results of research aimed at addressing this problem. A major theme of this work is the use of software algorithms and analysis principles to facilitate both investigation and control of the motor system. Though many of the algorithms are well known in computer science, their application to the field of motor restoration is novel. Associated with use of these algorithms are important methodological considerations such as speed of execution, convergence, and optimality. The first phase of the research involved development of a hardware and software platform designed to support a wide range of closed-loop response mapping and control routines. Software routines to automate three time-consuming tasks-mapping stimulus thresholds, mapping stimulus-response recruitment curves, and mapping electrode pair excitation overlap- were implemented and validated in a cat model. Computer control, combined with the use of an efficient binary search algorithm, reduced the time need to complete required implant mapping tasks by a factor of 4 or more (compared to manual mapping), making feasible-for the first time-acute experiments investigating multi-array, multijoint experimental limb control. The second phase of the research involved investigating the influence of stimulus timing, within multielectrode trains, on the smoothness of evoked muscle responses. A model for predicting responses was developed and used, in conjunction with function optimization techniques, to identify stimulus timings that minimize response variation (ripple). In-vivo validation demonstrated that low-ripple timings can be identified, and that the influence of timing on ripple depends largely on the response kinetics of the motor unit pools recruited by constituent electrodes. The final phase of the research involved using the response prediction model to simulate the behavior of a feedback-based, stimulus-timing adjustment algorithm. Multiple simulations were executed to assess the influence of three algorithm parameters-filter bandwidth, error sampling delay, and timing adjustment gain-on two performance metrics- convergence time and percent reduction in ripple. Results show that all parameters have an influence on algorithm performance. Convergence speed is the metric most a↵ected by parameter adjustment, improving by a factor of more than 3 (13 cycles to approximately 4 cycles). Ripple reduction is also a↵ected-exhibiting a 17% reduction with appropriate selection of error sampling delay. These results demonstrate the value of using this simulation approach for parameter tuning
Scientific and Ethical Considerations for Increasing Minority Participation in Clinical Trials
Since its inception, a major weakness in clinical trial research has been an inability to recruit diverse populations into clinical trials. These under-represented populations are mostly comprised of the poor, the elderly, children, women, and racial/ethnic minorities (African Americans and Hispanics). This fundamental weakness is further exacerbated by the fact that these same groups are often disproportionately affected by the diseases being studied in clinical trials. There are various patient specific, provider specific, and policy related causes for the existence of these disparities. Regardless of the cause, the lack of participation of these groups in clinical trials raises important questions about the quality and ethics of clinical research. The goal of this document is to discuss the evidence and reasons behind disparities in clinical trial participation. We also provide a discourse on potential mechanisms to address disparities in clinical trial accrual including the ethical considerations of financial incentives, the impact of a more stringent policy and review process for product approval from the Food and Drug Administration (FDA) including a diversity mandate with an associated population black box warning
Alien Registration- Wilder, Verna M. (Wade, Aroostook County)
https://digitalmaine.com/alien_docs/32716/thumbnail.jp
Effects of a Novel Dental Gel on Plaque and Gingivitis: A Comparative Study.
ObjectivesThe goal of this prospective, randomized, controlled, double-blinded study was to evaluate the effects of a novel dental gel on plaque and gingival health. The dental gel was designed to (1) break up and prevent re-accumulation of microbial biofilm, and (2) inhibit metal mediated inflammation.Materials and methodsTwenty-five subjects with moderate gingival inflammation (Löe and Silness Gingival Index ≥2) and pocket depths <4 were randomly assigned to brush twice daily for 21 days with the test or the control dental gel. On Days 0, 7, 14 and 21, plaque levels (Quigley-Hein, Turesky Modification Plaque Index), gingival inflammation (Löe and Silness Gingival Index) and gingival bleeding (modified Sulcus Bleeding Index) were determined by one blinded, investigator using a pressure sensitive probe.ResultsAfter 3 weeks, all 3 clinical indices were significantly improved in both groups (P<0.05) and significantly lower in the test group (P<0.05).ConclusionThe novel dental gel formulation was provided effective plaque control and reduced gingival inflammation.Clinical relevanceA novel dentifrice formulation may be an effective tool for plaque removal and maintaining gingival health
Highly porous photoluminescent diazaborole-linked polymers: synthesis, characterization, and application to selective gas adsorption
The formation of boron–nitrogen (B–N) bonds has been widely explored for the synthesis of small molecules, oligomers, or linear polymers; however, its use in constructing porous organic frameworks remains very scarce. In this study, three highly porous diazaborole-linked polymers (DBLPs) have been synthesized by condensation reactions using 2,3,6,7,14,15-hexaaminotriptycene and aryl boronic acids. DBLPs are microporous and exhibit high Brunauer–Emmett–Teller surface area (730–986 m2 g−1) which enable their use in small gas storage and separation. At ambient pressure, the amorphous polymers show high CO2 (DBLP-4: 4.5 mmol g−1 at 273 K) and H2 (DBLP-3: 2.13 wt% at 77 K) uptake while their physicochemical nature leads to high CO2/N2 (35–42) and moderate CO2/CH4 (4.9–6.2) selectivity. The electronic impact of integrating diazaborole moieties into the backbone of these polymers was investigated for DBLP-4 which exhibits green emission with a broad peak ranging from 350 to 680 nm upon excitation with 340 nm in DMF without photobleaching. This study demonstrates the effectiveness of B–N formation in targeting highly porous frameworks with promising optical properties
Control of unsteady separated flow associated with the dynamic stall of airfoils
An effort to understand and control the unsteady separated flow associated with the dynamic stall of airfoils was funded for three years through the NASA cooperative agreement program. As part of this effort a substantial data base was compiled detailing the effects various parameters have on the development of the dynamic stall flow field. Parameters studied include Mach number, pitch rate, and pitch history, as well as Reynolds number (through two different model chord lengths) and the condition of the boundary layer at the leading edge of the airfoil (through application of surface roughness). It was found for free stream Mach numbers as low as 0.4 that a region of supersonic flow forms on the leading edge of the suction surface of the airfoil at moderate angles of attack. The shocks which form in this supersonic region induce boundary-layer separation and advance the dynamic stall process. Under such conditions a supercritical airfoil profile is called for to produce a flow field having a weaker leading-edge pressure gradient and no leading-edge shocks. An airfoil having an adaptive-geometry, or dynamically deformable leading edge (DDLE), is under development as a unique active flow-control device. The DDLE, formed of carbon-fiber composite and fiberglass, can be flexed between a NACA 0012 profile and a supercritical profile in a controllable fashion while the airfoil is executing an angle-of-attack pitch-up maneuver. The dynamic stall data were recorded using point diffraction interferometry (PDI), a noninvasive measurement technique. A new high-speed cinematography system was developed for recording interferometric images. The system is capable of phase-locking with the pitching airfoil motion for real-time documentation of the development of the dynamic stall flow field. Computer-aided image analysis algorithms were developed for fast and accurate reduction of the images, improving interpretation of the results
Control of unsteady separated flow associated with the dynamic stall of airfoils
A unique active flow-control device is proposed for the control of unsteady separated flow associated with the dynamic stall of airfoils. The device is an adaptive-geometry leading-edge which will allow controlled, dynamic modification of the leading-edge profile of an airfoil while the airfoil is executing an angle-of-attack pitch-up maneuver. A carbon-fiber composite skin has been bench tested, and a wind tunnel model is under construction. A baseline parameter study of compressible dynamic stall was performed for flow over an NACA 0012 airfoil. Parameters included Mach number, pitch rate, pitch history, and boundary layer tripping. Dynamic stall data were recorded via point-diffraction interferometry and the interferograms were analyzed with in-house developed image processing software. A new high-speed phase-locked photographic image recording system was developed for real-time documentation of dynamic stall
Elasticity and internal friction through the kilocycle range: reviwe and annotated bibliography
A review of techniques and fundamentals of Young\u27s modulus and internal friction measurements is presented. The effect of porosity on elasticity is extensively reviewed as are factors contributing to internal friction. An annotated bibliography of 377 entries covering elasticity and internal friction measurements through the kilocycle frequency range is included and accompanied by a keyword index
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